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Administrative data

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

In vitro genetic toxicity data are available for diethylene glycol, triethylene glycol, and tetraethylene glycol, components of

the reaction mass of 3,6,9-trioxaundecane-1,11-diol and 2,2'-oxydiethanol and 2,2'-(ethylenedioxy)diethanol and 3,6,9,12-tetraoxatetrade.

Link to relevant study records

Referenceopen allclose all

Endpoint:
in vitro DNA damage and/or repair study
Remarks:
Type of genotoxicity: genome mutation
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
20 January - 31 July 1986
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP/Guideline study
Justification for type of information:
Read across is based on the category approach. Please refer to attached category document.
Qualifier:
according to
Guideline:
other: Environmental Protection Agency Health Effects Test Guidelines. HG-Gene Muta-Somatic cells, EPA Report No. 560/6-83-001, October 1983.
Deviations:
not specified
GLP compliance:
yes
Type of assay:
sister chromatid exchange assay in mammalian cells
Target gene:
HGPRT
Species / strain / cell type:
Chinese hamster Ovary (CHO)
Details on mammalian cell type (if applicable):
Chinese hamster ovary (CHO) cells were obtained from Abraham Hsie at Oak Ridge National Laboratory with the designation CH0-Kl-BH4-(subclone D1) (referred to simply as CHO for report purposes).
Metabolic activation:
with and without
Metabolic activation system:
Rat-liver S9 homogenate (prepared from Aroclor 1254 induced, Sprague-Dawley, male rats) is purchased from Hazleton Biotechnologies, Kensington, MD or Microbiological Associates, Bethesda, MD.
Test concentrations with justification for top dose:
0, 24, 29, 35, 42 and 50 mg/ml
Vehicle / solvent:
Test material was used neat.
Untreated negative controls:
not specified
Negative solvent / vehicle controls:
other: Cell culture medium was used for control samples
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
other: dimethylnitrosamine and ethylmethanesulfonate
Details on test system and experimental conditions:
CHO Mutation Test
Dose Selection - Appropriate concentrations for mutagenicity testing were determined by preliminary measurements of cytotoxicity to CHO cells of a range of concentrations tested both in the presence and absence of a rat-liver S9 metabolic activation system. Selection of a suitable range of concentrations for testing was based upon an estimate of the doses which would not produce excessive cytotoxicity to the treated cells. A dose of 50 mg/ml is the BRRC limit for the highest dose evaluated in testing freely-soluble, noncytotoxic chemicals in this test system. Cell-culture medium was used as the solvent for dilutions. All dilutions were prepared immediately prior to testing.

Test Procedure - Duplicate cultures of CHO cells were exposed for 5 hours to a minimum of five concentrations of tetraethylene glycol in tests both with and without the addition of a rat-liver S9 metabolic activation system. Various dose levels of tetraethylene glycol for testing were attained by direct addition of various aliquots of the undiluted test agent into the cell culture medium. The surviving fraction was determined at 18 to 24 hours after the removal of the test chemical using 4 plates/culture and 100 cells/plate. The mutant fraction was determined after a 9 to 12 day sub-culturing period to allow "expression" of the mutant phenotype. The mutant fraction was assessed in selective medium with 2 x 10(5) cells/plate in 5 plates/dosed culture (i.e. 1 x 10(6) total cells/dosed culture). The plating efficiency of these cells was assessed in non-selective medium using 4 plates/dosed culture with 100 cells/plate.

The mutagenicity/survival/plating efficiency data from at least the top five concentrations which allowed sufficient cell survival for assessment of survival and quantification of mutants are typically presented in the tables. The percentage of cells surviving the treatment, the numbers of mutant colonies, the percentage of clonable cells and the calculated number of mutants/10(6) clonable cells are presented in tabular form.

SCE Test
Dose Selection - Selection of a suitable range of doses for testing was based either upon cytotoxicity data obtained as part of the CHO mutation test or from preliminary experiments to determine cytotoxicity of the test chemical. For freely-soluble noncytotoxic chemicals, a maximum concentration of 50 mg/ml is used for this test system at BRRC to decrease the possibility of artefacts resulting from nonphysiological conditions in the cell-culture system.

Test Procedure - Production of SCEs following exposure to various concentrations of tetraethylene glycol was studied with duplicate cultures of CHO cells tested both with and without the incorporation of a rat-liver S9 metabolic activation system. Various concentrations of tetraethylene glycol for testing were attained by direct addition of various aliquots of the undiluted test agent into the culture medium.

For determination of direct genotoxic action, CHO cells were exposed to tetraethylene glycol and appropriate controls for 5 hours without S9 activation. Indirect activity, requiring metabolic activation by liver S9 homogenate, was studied with a 2-hour exposure period. Bromodeoxyuridine (BrdU), required to differentiate between the individual "sister" chromatids by SCE staining, was present at a concentration of 3 ug/ml in the growth medium during treatment and during the culture period following exposure. A total of twenty-five cells/concentration was examined for SCE frequencies using duplicate cultures. At least 5 dose levels were tested both with and without metabolic activation. SCE production was determined for the highest 3 doses which did not produce excessive cytotoxic inhibition of cell division. The number of SCEs/cell, mean number of SCEs/chromosome and the level of statistical significance of the increases above the concurrent solvent control values are presented in tabular form.

Osmolality - Published research has shown that conditions of high osmotic pressure can induce weak levels of chromosome damage. To assess the osmolality of each of the dose levels tested, various aliquots of the undiluted test sample were added directly to tissue culture medium to achieve the concentrations tested in the definitive chromosome aberration experiments. Osmolality was measured with an Advanced CRY0MATIC OSMOMETER (model 3 CII). Osmolality was assessed for culture conditions both with and without the presence of the S9 metabolic activation system. The osmolality of the culture medium alone was assessed as a reference point for evaluating the effects of the various concentrations of the test article.

Control Agents
Positive, negative and solvent control materials were tested concurrently with the test sample to assure both the sensitivity of the test systems and the concurrence of the results to historical test performance at BRRC. For the CHO and SCE assays, dimethylnitrosamine (DMN)-CAS #62-75-9 and ethylmethanesulfonate (EMS)-CAS #62-50-0 were used as positive control agents to assure the sensitivity and reliability of the test system for detecting metabolic activation dependent and independent mutagens, respectively. Cell culture medium was used as the negative control for statistical comparisons.

Metabolic Activation
S9 liver homogenate, prepared from Aroclor 1254-induced, Sprague-Dawley M A L E RATS, was purchased from Microbiological Associates, Bethesda, MD. The S9 preparation used for the CHO gene mutation test was found to have significant metabolic activity with three activation dependent positive control agents, tested for mutagenic activity by the supplier, using Salmonella bacterial strains TA98 and TA100. Following screening tests on this lot of S9 at BRRC a volume of 50 ul of S9 homogenate was found to be a suitable S9 concentration per milliliter of the S9 activation system.

For the two SCE tests, another lot of S9 homogenate, purchased from Litton Bionetics, Kensington, MD, contained 40 mg/ml protein and had a
benzo[cc]pyrene-hydroxylase activity of 15 nmol hydroxybenzpyrene/20 min/mg protein (assayed by Litton); a final concentration of 600 ug of S9 protein was used per 1.0 ml of the S9 activation mixture.

Typically 1.0 ml of the complete metabolic activation system (S9 homogenate plus cofactors) was added per each 4.0 ml of culture medium.
Evaluation criteria:
Evaluation of results from in vitro mutagenicity tests must take into consideration a comparison of both concurrent and historical control data for interpretation of the biological significance of the results. Each test system has been found to vary both within and between laboratories and evaluations only against concurrent controls may be misleading. The range of variability of negative control data for the tests at BRRC, updated as of December 31, 1985, is provided for comparative purposes. Because the data from many systems do not follow a normal distribution, the mean and median are both given as well as the 95 percentile range for typical test variability.

1. CHO mutation test
Negative controls: n = 30
mean = 4.0 mutants/10(6) clonable cells
S.D. = 7.0
median = 1.2 mutants/10(6) clonable cells
95 percentile range = 0 to 25.6 mutants/10(6) clonable cells
2. SCE test
Negative controls: n = 30
mean = 0.509 SCEs/chromosome
S.D. = 0.087
median = 0.498 SCEs/chromosome
95 percentile range = 0.227 to 0.666 SCEs/chromosome
Statistics:
Data from the SCE and CHO tests do not follow a normal distribution according to experience with historical controls. Thus, the data were analyzed after transformation of the mutation frequencies (MF) and SCE values according to the conversion method of Box and Cox (1964). This procedure for CHO data follows procedures described by Snee and Irr: (MF + l )( 0.15) (Snee, R.D. and J.D. Irr, Mutation Research, 85 (1981), 77-93). For CHO mutation studies with a concurrent control frequency of zero mutants, the variance of recent historical controls was used for the statistical analyses. For SCE data, statistical analyses of historical data at BRRC indicate that an exponent of 0.15 is the appropriate value for transformation of SCE values (BRRC Intramural Report 46-64). Positive controls for the CHO mutation test were run concurrently to assess the sensitivity of the assays in comparison to historical experience with the test system. Data for positive control agents were not compared statistically whenever differences were at least 5 times the concurrent negative control value and results were within the historical positive control range.
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Remarks:
HGPRT
Cytotoxicity / choice of top concentrations:
cytotoxicity
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
positive
Remarks:
SCE
Cytotoxicity / choice of top concentrations:
cytotoxicity
Additional information on results:
CHO MUTATION TEST
Selection of Test Concentrations
In a preliminary study, CHO cells were exposed for five hours to a range of concentrations from 0.003 to 50 mg/ml of the test material to
determine an appropriate cytotoxic range of doses. The relative cytotoxicity of the various concentrations, tested both in the presence and absence of an S9 metabolic activation system, was determined by measuring the relative growth of treated and control cells incubated overnight following removal of the test chemical. We observed that tetraethylene glycol was not remarkably cytotoxic to CHO cells even at 50 mg/ml, the highest dose generally used for this assay system at BRRC. Higher doses of tetraethylene glycol and other test chemicals are not tested because of the inherent potential for nonphysiological effects caused by the extremely high osmotic conditions of the cell culture medium.

For the definitive tests, a concentration range between 24 to 50 mg/ml was tested in the mutagenicity test without S9 (Tables 1 and 2) and in the presence of S9 (Tables 3 and 4.

Determination of Mutation Induction
Survival (Cytotoxicity)
Tables 1 and 3 present the cytotoxicity data determined by the plating efficiency of cells seeded into cloning plates at approximately 24 hours post-exposure to tetraethylene glycol.The test chemical produced dose-related cytotoxicity to CHO cells treated both with (Table 4) and without (Table 2) S9 metabolic activation. The decrease in plating efficiency of CHO cells indicates that biologically effective doses were tested and this likely is an underestimate of the cytotoxicity because of the 18 hr recovery period post-exposure.

Mutation
Tables 2 and 4 present the data for production of mutants by the test chemical and control agents. Tetraethylene glycol did not produce a dose-related increase in the number of mutants/106 viable cells over the range of concentrations tested either with or without the presence of an S9 metabolic activation system. No concentration of the test agent produced an increase in the incidence of mutations which was statistically different from the concurrent solvent control in the test with or without S9 activation. Small numerical increases in the mutant fraction obtained with some concentrations in both tests were within the historical control range of variability for this test system at BRRC. Also, these values were not statistically different from the concurrent control. Tetraethylene glycol was not mutagenic to CHO cells in the tests performed with and without metabolic activation.

Mutation values for the solvent controls for tests both with and without S9 activation were in an acceptable and low range based upon the variability for this test system experienced with historical control values at BRRC. Quantitative increases in the numbers of mutations of at least 5 to 10-fold greater than the concurrent controls were obtained for the DMN and EMS positive controls in all experiments and these values were within the expected range of values observed in previous experiments with this test system at BRRC. Positive control data were not compared statistically because of the obvious positive effects. Statistical comparisons to concurrent control values of zero were performed by using the variance values for the historical control data for this test at BRRC.

SCE TEST
Selection of Test Concentrations
In preliminary cytotoxicity tests, a concentration of 50 mg/ml produced 18.6% inhibition of culture growth when tested with an S9 metabolic activation system. The 50 mg/ml dose tested without metabolic activation produced approximately 21% growth inhibition.

For the definitive tests to determine potential effects upon SCEs, a range of doses from 24 mg/ml to 50 mg/ml was tested with and without addition of an S9 metabolic activation system. The highest three concentrations which permitted a suitably high mitotic index were examined for SCEs. A 50 mg/ml dose is the highest concentration evaluated in the test system at BRRC as possible artifacts may be caused by excessively high osmotic concentrations in in vitro chromosome tests (Galloway et. al. 1985, Env. Mutagenesis 7, Suppl. 3, pp 48-49).

Determinations of Effects upon SCEs
1. The data for SCE production in CHO cells treated with various dose levels of tetraethylene glycol or with positive, negative or solvent control agents without an S9 metabolic activation system are summarized in Table 5. A statistically significant increase in the number of SCEs was observed with all three dose levels of the test agent evaluated for SCEs. The magnitude of the increases was not remarkably high in comparison to positive control agents used for this test. Also, no definite dose-related trend was apparent in the data. The indication of consistent statistically significant differences from the control values indicated that the test result should be considered a weakly positive effect. However, a repeat test was considered necessary to determine the reproducibility of the SCE effects and to rule out the possibility of contaminants in the test sample.

The number of SCEs produced by the concurrent EMS positive control was highly statistically different from the values for the concurrent solvent controls. These data indicated an appropriate sensitivity of the test system comparable to our historical positive control data. The number of SCEs obtained with the solvent and medium controls were also in an acceptable range of values included in the variability encountered in our historical control values for this test at BRRC.

2. SCE values obtained following treatments of CHO cells with tetraethylene glycol in the presence of an S9 metabolic activation system are presented in Table 6. A statistically significant increase in the SCE values was produced with each of the three doses of the test agent evaluated for SCEs, in comparison to the concurrent controlin the presence of S9 activity. The magnitude of the increases and the absence of a distinct dose-related trend in the values was similar to the data obtained without S9 activation. Although the relative level of the SCE increases were low, the statistical indication of a significant difference above control values was used to consider the test as a positive indication of weak genotoxic activity. The biological significance of such low levels of activity at relatively high exposure concentrations must be evaluated with caution, both with regard to the possibility of contaminants in the test chemical and reproducibility of the positive effects.

The SCE values for the negative and solvent controls in the test with S9 activation were in an acceptable range of variability as encountered in previous experiments with this test system. Highly statistically significant numbers of SCEs were produced by the DMN positive control which indicated that the metabolic activation system was suitably active.

3. In the data from the test without S9, the highest dose (50 mg/ml) produced excessive inhibition of the numbers of cells in mitosis and it could not be scored. The remaining lower doses did not produce cell-cycle delays evident in this assessment.

In the test with S9 activation, no observable cell cycle delays were evident in the proportion of cells in the first and second mitotic division. The highest dose of 50 mg/ml was less cytotoxic than in the test without S9 and this dose was scored in the test.

The cytotoxicity data obtained from this test demonstrated that the doses evaluated for SCEs did not produce cell-cycle delays despite the use of extremely high concentrations.

SECTION III - SCE - Repeat Test
Purpose of Repeat Test
An initial sister chromatid exchange test on tetraethylene glycol (BRRC Sample No. 49-8) indicated a weak, but consistent, statistically significant effect upon the incidence of SCEs in CHO cells. This result was not considered sufficient for an unequivocal determination for two reasons: 1) the elevation in SCEs did not demonstrate a definite dose-related trend which is characteristic for positive genotoxic agents in this test system; and 2) analyses of the test chemical performed by the sponsor indicated that it contained higher levels of unknown impurities relative to the typical specifications for this material. A repeat test with a second sample of tetraethylene glycol with acceptable purity specifications was conducted to evaluate the reproducibility of the indication of genotoxic potential in the initial SCE test.

Determinations of Effects upon SCEs
1.The data for SCE production in CHO cells treated with various dose levels of tetraethylene glycol or with positive, negative or solvent control agents without an S9 metabolic activation system are summarized in Table 7.. A statistically significant increase in the number of SCEs was observed for all of the highest three test doses evaluated for SCEs. However, only the highest concentration evaluated (42 mg/ml) produced a consistent effect with both of the cell cultures treated with the test chemical. The lack of a definite dose-response trend in the SCE data was consistent with the results from the previous test on the first sample of tetraethylene glycol. The test result was considered to be a positive indication of genotoxic potential based upon the statistical indications of an increase over control values with three of the test doses evaluated. However, the biological significance of such weak, non-dose-related effects at high osmotic concentrations of the test agent should be evaluated with caution.

2. SCE values obtained following treatments of CHO cells with tetraethylene glycol in the presence of an S9 metabolic activation system are presented in Table 8. A statistically significant increase in the SCE values was produced with each of the three doses of the test agent evaluated for SCEs, in comparison to the concurrent control. The magnitude of the increases and the absence of a distinct dose-related trend in the values was similar to the data obtained without S9 activation. Although the relative level of the SCE increases were low, the statistical indication of a significant difference above control values was used to consider the test as a positive indication of weak genotoxic activity. The biological significance of such low levels of activity at relatively high exposure concentrations must be evaluated with caution, both with regard to the possibility of contaminants in the test chemical and reproducibility of the positive effects.

The test chemical was slightly less cytotoxic in the presence of the rat-liver activation mixture than observed in the test without activation. The data in this test showed similar statistical indications of a positive effect, low SCE increases, absence of clear dose-response trends and lack of reproducibility for duplicate cultures as those observed in the test without S9 activation. The reservations expressed in the previous section regarding the cautions interpretation of weak effects at extremely high doses must be reiterated for this test result. However, because of the statistically positive increases above the concurrent controls, the test was concluded to be a positive indication of weak genotoxic activity.

The SCE values for the negative controls in the test with S9 activation were in an acceptable range of variability as encountered in previous experiments with this test system. Highly statistically significant numbers of SCEs were produced by the DMN positive control which indicated that the metabolic activation system was suitably active.

3. In the data from the tests with and without S9, no remarkable increase in cells at the first mitotic division was observed on the slides evaluated for SCEs. The cytotoxicity data obtained from this test demonstrated that the doses evaluated for SCEs did not produce an adverse effect upon the progression of the cell population through the mitotic cycle.

Determination of the Osmolality of the Test Concentrations.
Nonphysiological conditions of high osmolality (>/= 450 mOsm/Kg H20) have been shown to produce significant levels of chromosome damage (Deasy et al. 1986; Galloway et al. 1985). The osmolality of the tissue culture medium and the various concentrations of the test article in the tissue culture medium tested was measured both in the presence and absence of an S9 metabolic activation system. Results are expressed in milliosmoles/Kg of H2O. The osmolality of the tissue culture medium used for the respective test exposures was 288 in the presence of S9 (minum serum) and 295 in the absence of S9 (plus 5% serum). The osmolality of the test concentrations of the test article which ranged from 423 mOsm/Kg H20 to 605 mOsm/Kg H20. The osmolality was similar for concentrations of each dose level prepared with or without S9. The highest concentration tested (50 mg/ml) had an osmotic strength that was twice that of the culture medium alone and all five concentrations of tetraethylene glycol that were tested exceeded 400 mOsm/Kg H20. In previous tests conducted at BRRC on a group of related glycols, no positive effects upon SCEs were noted with ethylene, diethylene and triethylene glycol within a similar or higher range of osmolalities. Thus, the absence of a direct relationship between SCE induction and osmolality for these related chemicals indicated that the results with tetraethylene glycol in this study in tests performed with and without S9 activation should be considered evidence for weak genotoxic activity.
Remarks on result:
other: slight, but statistically significant and repeatable increases in SCEs; not dose responsive

Table 1 Chinese Hamster Ovary (CHO) Mutation Assay: Determination of Cytotoxicity After Chemical Treatment Without Metabolic Activation

 Test Material  Total Number of Colonies  % Survival Mean (+/-SD)  % of Combined Solvent Controls
 Tetraethylene Glycol, mg/ml        Test Without S9 Activation
 24A  399  99.8 (7.9)  101.3
 24B  388  97.0 (4.1)  98.5
 29A  346  86.5 (7.4)  87.8
 29B  334  83.5 (2.9)  84.8
 35A  363  90.8 (11.1)  92.1
 35B  383  95.8 (16.6)  97.2
 42A  284  71.0 (8.4)  72.1
 42B  270  67.5 (1.3)  68.5
 50A  214  53.5 (11.7)  54.3
 50B  225  56.2 (9.7)  57.1
 Controls (Cell-culture medium)  389  97.2 (5.9)  98.7
 Controls (Cell-culture medium)  399  99.8 (17.9)  101.3
 Positive Control (EMS, 200 ug/ml)  393  98.2 (11.0)  99.7

*100 cells inoculated into each plate after approximately an 18 hr recovery period following removal of the test chemicals.

EMS - ethylmethanesulfonate.

Table 2 Chinese Hamster Ovary (CHO) Mutation Assay; Test Without Metabolic Activation System Results on Evaluation of Plating Efficiency and Mutant Frequencies Determined After Expression Period

      Mutant Colonies  Corrected***Mutation
  Test Material    Mean Colonies/Plate (+ S.D.)   % of CombinedSolvent Controls   Mean (+ S.D.)  Total Colonies**  Frequency (x10 -6)
  Tetraethylene glycol, mg/ml              Tested Without S9 Activation
 24A  104.2 (3.4)  94.9  1.0 (0.7)  5  4.8
 24B  122.0 (28.5)  111.2  0.8 (1.1)  4  3.3
 29A  110.8 (8.8)  101.0  0  0  0
 29B  91.5 (13.4)  83.4  0.2 (0.4)  1  1.1
 35A  126.0 (25.1)  114.8  0.6 (0.9)  3  2.4
 35B  92.8 (14.1)  84.6  0.2 (0.4)  1  1.1
 42A  126.5 (18.8)  115.3  0  0  0
 42B  113.8 (18.6)  103.7  1.8 (1.3)  9  7.9
 50A  103.5 (11.5)  94.3  0  0  0
 50B  93.8 (15.8)  85.5  0.6 (0.9)  3  3.2
 Control (Cell-culture medium)  122.0 (25.3)  111.2  0  0  0
 Control (Cell-culture medium)  97.5 (21.2)  88.8  0  0  0
 Positive control (EMS, 200 ug/ml)  106.0 (24.1)  96.6  29.6 (4.9)  148  139.6

** 2 x 105 cells inoculated in each of 5 plates, (1 x 106 total cells),

***Mutants/106 clonable cells: total # mutant colonies divided by viable fraction;

Statistical difference above control: a = 0.05 > p > 0.01; b = 0.01 > p > 0.001; c = p < 0.001.

No superscript indicates p > 0.05. Data for test chemical effects were analyzed by Method of Irr and Snee; data for positive controls were compared to historical ranges but were not analyzed statistically.

Table 3 Chinese Hamster Ovary (CHO) Mutation Assay: Determination of Cytotoxicity 24 Hours After Chemical Treatment With Metabolic Activation

 Test Material  Total Number of Colonies  % Survival Mean (+ S.D.)  % of Combined Solvent Controls
 Tetraethylene glycol, mg/ml        Test With S9 Activation
 24A  462  115.5 (19.8)  95.5
 24B  473  118.2 (23.8)  97.7
 29A  445  111.2 (17.6)  91.9
 29B  421  105.2 (5.7)  87.0
 35A  466  116.5 (31.4)  96.3
 35B  366  91.5 (7.8)  75.6
 42A  390  97.5 (23.8)  80.6
 42B  396  99.0 (14.7)  81.8
 50A  257  64.2 (5.1)  53.1
 50B  266  66.5 (11.7)  55.0
 Control (Cell-culture medium)  485  121.2 (16.4)  100.2
 Control (Cell-culture medium)  483  120.8 (26.5)  99.8
 Positive Control (DMN, 100 mg/ml)  174  43.5 (4.7)  36.0

DMN - dimethylnitrosamine

Table 4 Chinese Hamster Ovary (CHO) Mutation Assay; Test With Metabolic Activation System Results on Evaluation of Plating Efficiency and Mutant Frequencies Determined After Expression Period

      Plating Efficiency     Mutant Colonies  Corrected*** Mutation
 Test Material  Mean Colonies/Plate (+ S.D.)  % of Combined Solvent Controls  Mean (+ S.D.)  Total Colonies** Frequency (x10 -6
 Tetraethylene glycol, mg/ml              Tested With S9 Activation
 24A  96.0 (20.8)  90.0  0  0  0
 24B  106.2 (15.5)  99.5  0.4 (0.5)  2  1.9
 29A  91.8 (17.8)  86.0  2.2 (0.8)  11  12.0
 29B  96.5 (20.1)  90.4  0.4 (0.5)  2  2.1
 35A  101.2 (13.9)  94.8  0.2 (0.4)  1  1.0
 35B  113.0 (20.8)  105.9  1.4 (1.3)  7  6.2
 42A  102.5 (9.8)  96.1  1.2 (1.1)  6  5.9
 42B  102.2 (10.6)  95.8  0  0  0
 50A  115.2 (14.7)  108.0  0.4 (0.9)  2  1.7
 50B  104.8 (4.2)  98.2  0  0  0
 Control (Cell-culture medium)  103.2 (22.2)  96.7  1.6 (0.9)  8  7.7
 Control (Cell-culture medium)  110.2 (26.0)  103.3  0  0  0
 Positive control (DMN, 100 ug/ml)  88.0 (26.6)  82.5  31.2 (5.1)  156  177.3

** 2 x 105 cells inoculated in each of 5 plates, (1 x 106 total cells).

***Mutants/106 clonable cells: total # mutant colonies divided by viable fraction. Statistical difference above control: a = 0.05 > p > 0.01; b = 0.01 > p > 0.001; c = p < 0.001. No superscript indicates p > 0.05. Data for test chemical effects were analyzed by Method of Irr and Snee; data for positive controls were compared to historical ranges but were not analyzed statistically.

Table 5 Sister Chromatid Exchange (SCE) Assay; Production of SCEs by Tetraethylene Glycol Tested Without S9 Metabolic Activation - 5-Hour Treatment

  Test Material  Total # of  Total # of    Mean Number of SCEs/  Significance Above
   Tetraethylene glycol, mg/ml
 Chromosomes  SCEs  SCEs/Cell*  Chromosome** (+ S.D.)  Solvent Controls***
29A  498  363  14.5  0.73 (0.25)  c
 29B  501  355  14.2  0.71 (0.12)  c
 35A  496  369  14.8  0.74 (0.29)  c
 35B  500  411  16.4  0.82 (0.23)  c
 42A  497  371  14.8  0.75 (0.24)  c
 42B  496  418  16.7  0.84 (0.19)  c
 Control (Cell-culture medium)  499  232  9.3  0.46 (0.14)  -
 Control (Cell-culture medium)  501  243  9.7  0.49 (0.15)  -
 Positive Control (EMS, 100 ug/ml)  500  673  26.9  1.35 (0.25)  c

* Twenty-five cells examined per dosed culture.

** Mean value of SCE/chromosome determined from the values of the individual cells examined.

***Statistical significance above solvent control: c: p < 0.001.

Data analyzed by Student's t-test by comparing individual test groups with the combined solvent control groups. Significances noted in parentheses are the combined test groups compared statistically against the combined solvent controls.

EMS - ethylmethanesulfonate

Table 6 Sister Chromatid Exchange (SCE) Assay: Production of SCEs by Tetraethylene Glycol Tested With S9 Metabolic Activation - 2-Hour Treatment

 Test Material  Total # of  Total # of    Mean Num ber of SCEs/  Significance Above
 Tetraethylene glycol, mg/ml  Chromosomes  SCEs  SCEs/Cell*   Chromosomes** (+S.D.)   Solvent Controls***
 35A  501  342  13.7  0.68 (0.20)  c
 35B  502  384  15.4  0.76 (0.22)  c
 42A  500  384  15.4  0.77 (0.30)  c
 42B  499  381  15.2  0.76 (0.18)  c
 50A  497  405  16.2  0.82 (0.28)  c
 50B  504  374  15.0  0.74 (0.23)  c
 Control (Cell-culture medium)  499  248  9.9  0.50 (0.14)  -
 Control (Cell-culture medium)  501  248  9.9  0.50 (0.11)  -
 Positive Control (DMN, 300 ug/ml)  499  889  35.6  1.78 (0.53)  c

* Twenty-five cells examined per dose level.

** Mean value of SCE/chromosome determined from the values of the individual cells examined.

*** Statistical significance above solvent control: c: p < 0.001.

Data analyzed by Student's t-test by comparing individual test groups with the combined solvent control groups. Significances noted in parentheses are the combined test groups compared statistically against the combined solvent controls.

DMN-Dimethylnitrosamine

Table 7 Sister Chromatid Exchange (SCE) Assay: Production of SCEs by Tetraethylene Glycol Tested Without S9 Metabolic Activation - 5-Hour Treatment

 Test Material  Total # of  Total # of    Mean Number SCEs/  Significance Above
 Tetraethylene glycol, mg/ml  Chromosomes  SCEs  SCEs/Cell*  Chromosome** (+S.D.)  Solvent Controls***
 29A  496  281  11.2  0.56 (0.18)  NS
 29B  498  353  14.1  0.71 (0.14)  c
 35A  497  346  13.8  0.70 (0.23)  c
 35B  499  283  11.3  0.57 (0.19)  NS
 42A  497  327  13.1  0.66 (0.17)  c
 42B  499  330  13.2  0.66 (0.16)  c
 50  cytotoxic - too few mitotic cells were available to score            
 Control (Cell-culture medium)  501  235  9.4  0.47 (0.09)  
 Control (Cell-culture medium)  499  243  9.7  0.49 (0.17)  
 Positive Control (EMS, 100 ug/ml)  504  644  25.8  1.28 (0.23)  c

* Twenty-five cells examined per dosed culture.

** Mean value of SCE/chromosome determined from the values of the individual cells examined.

***Statistical significance above solvent control: c: p < 0.001; NS: p > 0.05.

Data analyzed by Student's t-test by comparing individual test groups with the combined solvent control groups. Significances noted in parentheses are the combined test groups compared statistically with the combined solvent controls.

EMS - ethylmethanesulfonate

Table 8 Sister Chromatid Exchange (SCE) Assay: Production of SCEs by Tetraethylene Glycol Tested With S9 Metabolic Activation - 2-Hour Treatment

 Test Material  Total # of  Total # of    Mean Number of SCEs/  Significance Above
 Tetraethyene glycol, mg/ml  Chromosomes  SCEs  SCEs/Cell*  Chromosome** (+S.D.)  Solvent Controls***
 35A  503  356  14.2  0.71 (0.22)  c
 35B  496  312  12.5  0.63 (0.17)  NS
 42A  498  287  11.5  0.58 (0.16)  NS
 42B  498  346  13.8  0.70 (0.21)  b
 50A  498  360  14.4  0.72 (0.24)  c
 50B  494  363  14.5  0.74 (0.31)  c
 Control (Cell-culture medium)  498  259  10.4  0.52 (0.14)  
 Control (Cell-culture medium)  489  248  9.9  0.51 (0.17)  
 Positive Control (DMN, 300 ug/ml)  495  1339  53.6  2.70 (0.94)  c

* Twenty-five cells examined per dose level.

** Mean value of SCE/chromosome determined from the values of the individual cells examined.

*** Statistical significance above solvent control: b: 0.01 > p > 0.001; c: p < 0.001; NS: p > 0.05.

Data analyzed by Student's t-test by comparing individual test groups with the combined solvent control groups. Significances noted in parentheses are the combined test groups analyzed against the combined, solvent controls.

DMN-Dimethylnitrosamine

Conclusions:
Interpretation of results (migrated information):
ambiguous SCE
negative HGPRT forward mutation assay

Tetraethylene glycol produced weak but statistically significant increases in the incidence of SCEs over the range of concentrations tested with or
without addition of an active S9 metabolic activation system. However, no definite, dose-related effects of exposure on the incidence of SCEs were
evident. Although the biological significance of the results must be evaluated with caution because of the high range of osmotic concentrations evaluated, tetraethylene glycol produced reproducibly positive increases in the incidence of SCEs in CHO cells with the relatively high range of exposure concentrations used for these studies.
Executive summary:

Tetraethylene glycol was evaluated for potential genotoxic activity using the Chinese Hamster Ovary (CHO) gene mutation test and the sister chromatid exchange (SCE) test. The results indicated that tetraethylene glycol did not produce a dose-related or repeatable, significant mutagenic effect in the CHO gene mutation assay in the tests with and without S9 activation. The lack of gene mutation activity for tetraethylene glycol was consistent with the lack of mutagenic effects in a previous Ames (Salmonella) gene mutation test

conducted previously (BRRC Project Report 49-59).

Results from a sister chromatid exchange assay indicated that tetraethylene glycol produced statistically significant increases of SCEs in tests with and without rat-liver S9 activation, but the increases did not occur with a dose-related trend characteristic of genotoxic agents. The reproducibility of these equivocal effects was evaluated with a second sample of tetraethylene glycol, because analyses performed by the sponsor revealed an atypical concentration of unidentified impurities in the first sample. The repeat SCE test on a sample of acceptable purity produced essentially identical increases in the incidence of SCEs as obtained with the first test. This weakly positive increase in SCEs was consistent with results in chromosome aberration tests with CHO cells conducted on the first sample of tetraethylene glycol at BRRC (BRRC Project Report 49-90).

The biological significance of weak effects at very high test concentrations must be interpreted with caution because of the possibility of spurious effects caused by the significant alteration of the osmotic strength of the cell-culture medium at these high test concentrations. Conditions of high osmolality (> 450 mOsm/Kg H2O) produced by noncytotoxic chemicals such as tetraethylene glycol can produce increased incidences of sister chromatid exchanges and chromosome aberrations (Galloway et al. 1985; Deasy et al. 1986). The osmolality of the test concentrations of tetraethylene glycol used for this study was determined to be in the approximate range of 423 to 605 mOsm/Kg H2O in comparison to 288 to 295 mOsm/Kg H2O for the cell culture medium alone.

Thus, the possibility that the weak effects observed in this study were the result of a minor contaminant or caused by a physiological artifact cannot be excluded. However, in previous studies on related glycols (e.g. ethylene-, diethylene- and triethylene glycol) no positive increases in SCEs were observed following exposure to a similar or higher range of osmolalities (BRRC reports 44-56; 47-94; 49-83).

The observation of low level but statistically significant increases in SCEs in tests both with and without S9 activation indicated that tetraethylene glycol produced positive increases in SCEs following the criteria employed to evaluate this test at BRRC. However, the biological significance of these weakly positive effects must be interpreted with caution, both because of the lack of unequivocal dose-response data and the high osmolality conditions employed in the in vitro test system.

Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
17 March - 20 March 1986
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP/Guideline study.
Justification for type of information:
Read across is based on the category approach. Please refer to attached category document.
Qualifier:
equivalent or similar to
Guideline:
other: Environmental Protection Agency, Health Effects Test Guidelines, HG-Gene Muta-S. QLBimiAm, EPA Report No. 560/6-84-002, October, 1984.
Deviations:
not specified
GLP compliance:
yes
Type of assay:
bacterial reverse mutation assay
Target gene:
Histidine
Species / strain / cell type:
S. typhimurium, other: TA98, TA100, TA1535, TA1537 and TA1538
Metabolic activation:
with and without
Metabolic activation system:
S9 liver homogenate, prepared from Aroclor 1254-induced, Sprague-Dawley male rats, was purchased from Microbiological Associates8 Bethesda, MD.
Test concentrations with justification for top dose:
0, 1, 3, 10, 30 and 112.6 mg/plate
Vehicle / solvent:
water
Untreated negative controls:
not specified
Negative solvent / vehicle controls:
yes
True negative controls:
not specified
Positive controls:
yes
Positive control substance:
other: Without S9 used 4-nitro-o-phenylenediamine for TA98 and TA1538, sodium azide for TA100 and TA1535, and 9-aminoacridine for TA1537. With S9 used 2-aminoanthracene (2-anthramine) for all strains.
Details on test system and experimental conditions:
Toxicity Testing
Sterile tubes are prepared containing 2 ml soft agar (6 g/1 agar and 5 g/1 NaCl) with a final concentration of 0.05 mM L-histidine and 0.05 mM D-biotin (the entire mixture is called top agar). Dilutions of the test chemical are made in an appropriate solvent so that the correct amount of chemical can be added to each tube in 100 ul amounts. If less than 100 ul amounts of the test chemical is used, phosphate-buffered saline is used to adjust the total volume to 100 ul.

At least five doses are tested with maximum doses of 50 mg (for solids) or 100 ul (for liquids) per plate for nontoxic chemicals, unless limited by solubility. Generally, a chemical cannot be considered to be nonmutagenic unless at least 5 mg/plate has been tested, unless limited by toxicity or solubility (deSerres and Shelby, 1979; HG-Gene Muta-S. tvphimuriumf October, 1984). A 100 ul aliquot of an overnight broth culture of strain TA100 is added followed by the appropriate amount of test chemical. The mixture is vortexed and poured onto the surface of a Vogel-Bonner Medium E agar plate (VB-E plate). The top agar is allowed to harden and the plates are incubated at 37°C for 24 to 48 hours. The plates are examined for the condition of their background lawns and growth is recorded as either confluent, sparse, or absent. Confluency is considered an indication of nontoxicity, sparse growth indicates moderate toxicity, and lack of growth is recorded as toxic.

Controls
Concurrent solvent and positive controls are run with each test. The solvent control is the maximum amount of solvent added with the diluted test chemical. For chemicals tested without dilution (i.e., by direct addition), water is used as the solvent control. Both activation-dependent and activation-Independent positive controls are used. The activation-independent controls are 4-nitro-o-phenylenediamine for TA98 and TA1538, sodium azide for TA100 and TA1535, and 9-aminoacridine for TA1537. The activation-dependent control in 2-aminoanthracene (2-anthramine) for all strains. The concentrations are determined from prior dose-response experiments on these chemicals and are listed in the tables of results in this report.

Sample Preparation:
An initial stock solution of the test substance was prepared by mixing tetraethylene glycol in water to achieve a concentration of 300 mg/ml. All subsequent dilutions were made in the same solvent. Dilutions of the test substance were made fresh each day of testing. All dilutions for the mutagenicity tests were analyzed gravimetricaHy to determine actual concentrations.

Testing:
The test chemical was tested in triplicate at five doses chosen to span a range which included moderately toxic to relatively nontoxic concentrations. The test substance was nontoxic in the preliminary toxicity test; thus, 100 ul of liquid was used as the maximum dose. Testing was performed both with and without metabolic activation. Concurrent solvent and positive controls were tested in each experiment.

Data Collection
Bacterial colonies are counted manually or by an Artek Model #880 Colony Counter, or equivalent. The counter is calibrated for each test to check the
counting accuracy. The numbers of colonies per plate are counted and recorded. An examination is also made of the background lawn on each plate. If toxicity is observed as an inhibition of growth of the background lawn, the plate is not counted, but is recorded as toxic. If the background lawn is sparse and the colony count is still recorded, that number is not used in the calculation of the mean number of colonies and its standard deviation. A reduction in the number of spontaneous revertant colonies is also an indication of toxicity, and these are labelled "toxic" when the average number of colonies is less than one half of the average number for the solvent control.
Evaluation criteria:
The spontaneous reversion for the solvent controls should be within this laboratory's historical range. The positive controls should demonstrate that the test systems are responsive with known mutagens. A test chemical is considered to be a bacterial mutagen if the number of revertant colonies is at least twice the solvent control for at least one dose level and there is evidence of a dose-related increase in the number of revertant colonies. If a test chemical produces a marginal or weak response that cannot be reproduced in a second test, the test result will be considered negative. If there is no evidence of a dose-related increase in the number of revertant colonies and the number of revertant colonies is not twice the solvent control, then the test chemical is not considered to be a bacterial mutagen,
Statistics:
Means and Standard Deviations were calculated.
Species / strain:
S. typhimurium, other: TA98, TA100, TA1535, TA1537 and TA1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity nor precipitates, but tested up to recommended limit concentrations
Vehicle controls validity:
valid
Untreated negative controls validity:
not specified
Positive controls validity:
valid
Additional information on results:
Tetraethylene glycol was tested in a preliminary toxicity screen at 112.6, 30, 10, 5, 3, 1, 0.3, 0.1, 0.03, and 0.01 milligrams per plate with strain TA100 only. When possible, the highest dose level for definitive testing is selected to produce some degree of cytotoxicity based on the preliminary toxicity test results. However in this study, no cytotoxicity was evident in the preliminary test and tetraethylene glycol did not decrease either the number of revertant colonies or the growth of the background lawn. Thus, a testable dose of 100 ul/plate (112.6 mg/plate) was the highest dose level tested and four additional half-log doses ranging from 1.0 mg/plate to 30 mg/plate were tested in the definitive mutagenicity experiments.

Numbers of revertant colonies per plate and the respective means and standard deviations of each dose for each strain of bacteria are shown in Table 1 (without activation) and in Table 2 (with activation). No indication of mutagenicity was observed at any of the tested doses, either by evidence of a dose-response relationship or a doubling of the number of colonies over the solvent control.

All strains exhibited a positive mutagenic response with the positive controls tested both with and without S9 metabolic activation. Negative (solvent) controls were also tested with each strain, and the number of spontaneous revertants was within the historical range of variation observed at this laboratory (see Appendix 3). All positive and negative controls were tested concurrently with the test chemical. Concurrent sterility test results showed that the mixture of S9, PBS, the test chemical and all solvents and controls were sterile.
Remarks on result:
other: all strains/cell types tested

Table 1 RESULTS OF THE SALMONELLA MUTAGENICITY ASSAY - Without Activation

 Test Material  Dose per plate  Mean + S.D.
 TA98    
 Solvent (water)  100 mg  27 + 6.4
 4 -NPD  0.01 mg  1038 + 20.4
 TTEG  1 mg  31 + 2.1
 TTEG  3 mg  35 + 7.0
 TTEG  10 mg  29 + 6.8
 TTEG  30 mg  37 + 6.7
 TTEG  112.6 mg  39 + 5.5
 TA100    
 Solvent (water)  100 mg  125 + 6.4
 NaN3  0.01 mg  1837 + 37.0
 TTEG  1 mg  109 + 8.7
 TTEG  3 mg  124 + 7.8
 TTEG  10 mg  127 + 20.4
 TTEG  30 mg  136 + 1.0
 TTEG  112.6 mg  128 + 18.0
 TA1535    
 Solvent (water)  100 mg  38 + 6.4
 NaN3  0.01 mg  1800 + 24.0
 TTEG  1 mg  39 + 2.0
 TTEG  3 mg  50 + 1.5
 TTEG  10 mg  40 + 4.7
 TTEG  30 mg  40 + 6.7
 TTEG  112.6 mg  37 + 8.1
 TA1537    
 Solvent (water)  100 mg  5 + 1.5
 9 -AA  0.06 mg  84 + 15.3
 TTEG  1 mg  5 + 1.0
 TTEG  3 mg  7 + 1.7
 TTEG  10 mg  7 + 2.6
 TTEG  30 mg  5 + 1.0
 TTEG  112.6 mg  8 + 1.5
 TA1538    
 Solvent (water)  100 mg  8 + 1.5
 4 -NPD  0.01 mg  1001 + 86.9
 TTEG  1 mg  8 + 1.0
 TTEG  3 mg  6 + 0
 TTEG  10 mg  6 + 1.5
 TTEG  30 mg  8 + 4.0
 TTEG  112.6 mg  9 + 4.2

TTEG: Tetraethylene glycol

4-NPD: 4-NITRO-O-PHENYLENEDIAMINE;

NaN3: SODIUM AZIDE

9-AA: 9-AMINOACRIDINE

Table 2 RESULTS OF THE SALMONELLA MUTAGENICITY ASSAY - With Activation

 Test Material  Dose per plate  Mean+S.D.
 TA98    
 Solvent (water)  100 mg  26 + 4.0
 2 -AA  0.01 mg  2284 + 195.8
 TTEG  1 mg  28 + 2.5
 TTEG  3 mg  33 + 2.6
 TTEG  10 mg  25 + 2.3
 TTEG  30 mg  33 + 6.0
 TTEG  112.6 mg  29 + 7.0
 TA100    
 Solvent (water)  100 mg  91 + 11.8
 2 -AA  0.01 mg  1409 + 228.3
 TTEG  1 mg  101 + 5.2
 TTEG  3 mg  83 + 3.6
 TTEG  10 mg  89 + 12.9
 TTEG  30 mg  90 + 12.1
 TTEG  112.6 mg  102 + 14.4
 TA1535    
 Solvent (water)  100 mg  12 + 3.2
 2 -AA  0.01 mg  120 + 19.3
 TTEG  1 mg  11 + 4.9
 TTEG  3 mg  11 + 3.2
 TTEG  10 mg  12 + 5.5
 TTEG  30 mg  10 + 2.3
 TTEG  112.6 mg  11 + 2.5
 TA1537    
 Solvent (water)  100 mg  7 + 1.5
 2 -AA  0.01 mg  166 + 46.1
 TTEG  1 mg  5 + 1.0
 TTEG  3 mg  5 + 2.3
 TTEG  10 mg  4 + 2.1
 TTEG  30 mg  5 + 1.7
 TTEG  112.6 mg  7 + 0.6
 TA1538    
 Solvent (water)  100 mg  11 + 3.1
 2 -AA  0.01 mg  1010 + 187.9
 TTEG  1 mg  18 + 4.0
 TTEG  3 mg  15 + 3.8
 TTEG  10 mg  19 + 3.8
 TTEG  30 mg  21 + 4.9
 TTEG  112.6 mg  17 + 3.0

TTEG: Tetraethylene glycol

2-AA: 2-AMINOANTHRACENE

Conclusions:
Interpretation of results (migrated information):
negative

Tetraethylene glycol did not produce a dose dependent mutagenic response in any of the Salmonella typhimurium strains that were tested with or without a metabolic activation system. Under the conditions of this assay, tetraethylene glycol was not mutagenic in the Salmonella/microsome mutagenicity assay.
Executive summary:

Tetraethylene glycol was tested for potential mutagenic activity using the Salmonella/microsome bacterial mutagenicity assay (Ames test). Test doses for the Ames test were chosen from data obtained in a preliminary study which indicated that all concentrations tested including the maximum concentration established by BRRC standard protocol for this test system (100 μl/plate), allowed confluent growth of the background lawn and did not produce evidence of cytotoxicity. In the definitive mutagenicity testing five concentrations of tetraethylene glycol ranging from 1.0 mg/plate to 112.6 mg/plate were tested with or without metabolic activation using triplicate cultures at each dose level.

Mutagenic activity was not observed with any of the five bacterial strains tested with or without metabolic activation. Tetraethylene glycol was not considered to be mutagenic in this in vitro bacterial test system.

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: acceptable study, meets basic scientific principles
Justification for type of information:
Read across is based on the category approach. Please refer to attached category document.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
GLP compliance:
yes (incl. certificate)
Remarks:
testing lab.
Type of assay:
in vitro mammalian chromosome aberration test
Target gene:
CHO cells
Species / strain / cell type:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Metabolic activation system:
rat liver S-9 mix
Test concentrations with justification for top dose:
0.0, 35, 42, 50 mg/ml
Vehicle / solvent:
water
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
yes
Positive controls:
yes
Positive control substance:
other: cyclophosphamide and triethylene melamine
Details on test system and experimental conditions:
Dose selection: Appropriate concentrations for cytogenetic testing were determined by preliminary measurements of cytotoxicity to CHO cells using a broad range of concentrations from 1 - 50 mg/ml tested both the presence and absence of a rat liver S-9 metabolic activation system.
Selection of a suitable range of concentrations for testing was based upon an estimate of the doses which would not excessively inhibit mitotic cell invision of the treated cells. A maximum concentration of 50 mg/ml is tested for non-cytotoxic test chemicals.
Test procedure: For evaluation of direct clastogenic potential, CHO cells were exposed to TEG and appropriate controls for a continuous 6- or 10-hour period without S-9 activation. Indirect genotoxic potential, requiring metabolic activation by liver S-9 homogenate, was studied with a 2-hour exposure period to test chemical and S-9 activation system. Following the 2-h exposure period, cells were rinsed, fresh medium was added and cells were then harvested at 6 and 10 h after the start of exposure. Chromosomes were prepared by standard procedures. A total of 50 cells/culture/harvest interval was examined for chromosome damage using duplicate cultures for the test agent and solvent controls. At least 5 dose levels were tested both with and without metabolic activation. Incidence of chromosome damage was determined for the highest 3 doses which did not produce excessive cytotoxic inhibition of cell division (mitosis).
Statistics:
Analyses of the test data employed the Fisher's Exact Test (one-tailed) to determine statistical significance and differences between the test and control populations.
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
no cytotoxicity
Vehicle controls validity:
not specified
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Results obtained in this study demonstrated that the test substance did not produce significant increases in the proportion of cells with chromosome aberrations. The predominant type of chromosome damage observed in this study was simple chromatid breakage. None of the other types of typical chromosome damage scored in this test system were remarkable different from normal variations generally encountered with these cultured cells.
Remarks on result:
other: all strains/cell types tested
Conclusions:
Interpretation of results (migrated information):
negative

Results obtained in tests with and without an S9 metabolic activation system indicated that the test substance did not produce increases in chromosome aberrations in comparison to values of control cultures. No evidence of clastogenic or cytotoxic effects were observed under the conditions of this system.
Endpoint:
in vitro gene mutation study in bacteria
Remarks:
Type of genotoxicity: gene mutation
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: basic information given restrictions: only short abstract available, E. coli not tested
Justification for type of information:
Read across is based on the category approach. Please refer to attached category document.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
GLP compliance:
yes (incl. certificate)
Remarks:
testing lab.
Type of assay:
bacterial reverse mutation assay
Target gene:
S. typhimurium strains
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Metabolic activation system:
rat liver S-9 mix
Test concentrations with justification for top dose:
1.0 - 112.6 mg/plate
Vehicle / solvent:
water
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Remarks:
water
True negative controls:
yes
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenylendiamine, 9-azinoacridine, sodium azide, 2-aminoanthracene
Details on test system and experimental conditions:
Sample preparations: An initial stock solution of the test substance was prepared by mixing the test substance in water to achieve a contentratIon of 300 mg/ml. All subsequent dilutions were made in the same solvent. Dilutions of the test substance were made fresh each day of testing. All dilutions for the mutagenicity tests were analyzed gravimetrically to determine actual concentrations.
Dose selection: A preliminary toxicity test was performed using strain TA100 to determine the level of toxicity of the test substance. 10 doses were tested for toxicity with a plate assay performed in the manner used for mutagenicity determinations. Toxicity was assessed at 24 to 48 hours after treatment by observations for either growth inhibition of the background lawn or a reduction in the number of spantaneous mutants.
Testing: The test chemical was tested in triplicate at 5 doses chosen to span a range which included moderately toxic to relatively non-toxic concentrations. The test substance was non-toxic in the preliminary toxicity test; thus, 100 ul of liquid was used as the maximum dose. Testing was performed both with and without metabolic activation. Concurrent solvent and positive controls were tested in each experiment.
Evaluation criteria:
no data
Statistics:
no data
Species / strain:
S. typhimurium, other: TA98, TA100, TA1535, TA1537, TA1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: No cytotoxicity were found based on the preliminary toxicity test results.
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
No indication of mutagenicity was observed at any of the tested doses, either by evidence of a dose-response relationship or a doubling of the number of colonies over the solvent control.
All strains exhibited a positive mutagenic response with the positive controls tested both with and without metabolic activation. Negative (solvent) controls were also tested with each strain, and the number of spontaneous revertants was within the historical range of variation observed. All positive and negative controls were tested concurrently with the test chemical. Concurrent sterility test results showed that the mixture of S9, PBS, the test chemical and all solvents and controls were sterile.
Remarks on result:
other: all strains/cell types tested
Conclusions:
Interpretation of results (migrated information):
negative

Triethylene glycol did not produce a dose-dependent mutagenic response in any of the S. typhimurium strains that were tested with or without a metabolic activation system. All average colony numbers were less than two times the respective concurrent solvent control values. Under the conditions of this assay, TEG was not mutagenic in the Salmonella/microsome mutagenicity assay.
Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: well-documented, acceptable study report
Justification for type of information:
Read across is based on the category approach. Please refer to attached category document.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
GLP compliance:
yes (incl. certificate)
Remarks:
testing lab.
Type of assay:
in vitro mammalian chromosome aberration test
Target gene:
CHO cells
Species / strain / cell type:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Metabolic activation system:
rat liver S-9 mix
Test concentrations with justification for top dose:
<= 50 mg/ml
Vehicle / solvent:
Test chemical was added directly into the cell culture medium of the test systems.
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
yes
Positive controls:
yes
Positive control substance:
other: dimethylnitrosamine and ethylmethanesulfonate
Details on test system and experimental conditions:
Selection of Test Concentrations: Preliminary experiments were performed with CHO cells to determine an appropriate range of test concentrations in which the highest concentration would not produce excessive inhibition of the mitotic index. Test results wíth diethylene glycol indicated that concentrations up to 50 mg/ml, tested respectively with and without S9 metabolic activation, produced no detectable cytotoxic effects upon cell culture growth or mitotic indices. The 50 mg/ml (5.°G w/v) dose is the maximum dose used in the standard BRRC protocol and it was the highest dose tested with and without S9 activation in this study.
Test Procedures: For evaluations of direct clastogenic potential, CHO cells were exposed to diethylene glycol and appropriate controls for the complete 12 hour period without S9 activation. Determination of indirect genotoxic potential, requiring metabolic activation by liver S9-homogenate, was studied with a 2-hour exposure period to the test chemical and S9 activation system. Cells were sampled at 8 hr and at 12 hr after starting exposure to the test agent and chromosomes were prepared by standard procedures. A total of fifty cells/culture/harvest interval was examined for chromosome damage using duplicate cultures for the test agent and solvent controls. At least 5 dose levels were tested both with and without metabolic activation. Incidence of chromosome damage was determined for the highest 3 doses which did not produce excessive cytotoxic inhibition of cell division (mitosis). The number of chromatid and chromosome-type aberrations, the total number of aberrations per 50 cells examined (with and without including gaps in the total) and the level of statistical significance of the increases of aberrant cells are presented in tabular form.
Control Agents: Positive and solvent control materials were tested concurrently with the test sample to assure the sensitivity of the test system. Cyclophosphamide (CAS 50-18-0) and triethylenemelamine (CAS 51-18-3) were used as the positive control agents to assure the reliability and sensitivity of the test system for detecting metabolic activation dependent and independent clastogens, respectively. Cell culture medium was used as the vehicle and solvent control agent for this test chemical. The positive control agents were assessed for chromosome aberration frequencies only at 8 hr after treatment initiation using single cultures.
Metabolic Activation: S9 liver homogenate, prepared from Aroclor l254-induced, Sprague-Dawley male rats, as purchased from Microbiological Associates (MBA), Bethesda, MD. The S9 preparation was screened for metabolic activity by the supplier and at BRRC prior to use in our general testing program. Data from MBA showed that the S9 preparation was active with three different activation dependent mutagens in Salmonella bacterial strains TA98 and TA100.

Evaluation criteria:
The criteria for evaluation of a positive or negative response depend both on the level of statistical significance and subjective analyses of concurrent and historical control data. The key determinant is whether a dose-dependent increase in SCEs is induced by the test agent. When no clear dose-response relationship is evident and when one or more responses of marginal indications of statistical differences are obtained, a careful examination of the data in comparison to the concurrent controls and the historical data base is necessary to determine the biological significance of the statistical indicators. Testing may be repeated to clarify unusual responses, if data for the concurrent positive or negative controls suggest a defect in the original experiment. Overall assessment will also rely on corroborating data from the other tests in the testing battery. Clearly positive responses will include any of the following: (1) Doubling in the SCE frequency by any single concentrations with both of the duplicate cultures/dose; (2) statistically significant responses of p < 0.05 with two or more consecutive concentrations and (3) induction of a statistically significant, dose-related increase in the number of SCE. Repeatability of effects in the two individual cultures/dose will be used as an important determinant in the classification of a biologically significant effect.
Statistics:
The data were analyzed after transformation of the mutation frequencies (MF) and SCE values according to the conversion method of Box and Cox (1964) . For CHO mutation studies with a concurrent control frequency of zero mutants, the variance of recent historical controls was used for the statistical analyses. For SCE data, statistical analyses of historical data at BRRC indicate that an exponent of 0.15 is the appropriate value for transformation of SCE values. Positive controls for the CHO mutation test were run concurrently to assess the sensitivity of the assays in comparison to historical experience with the test system. Data for positive control agents were not compared statistically whenever differences were at least 5 times the concurrent negative control value and results were within the historical positive control range.
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: > 50 mg/ml
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
The relative cytotoxicity of the various concentrations, tested both in the presence and absence of an S9 metabolic activation system, was determined by measuring the relative growth of treated and control cells incubated overnight following removal of the test chemical. The authors observed that diethylene glycol was not highly cytotoxic when tested either with or without S9 metabolic activation. A concentration of 50 mg/ml produced 16% inhibition of growth without S9 and 27% inhibition with S9. For the definitive tests, a concentration range between 30 to 50 mg/ml was tested in the mutagenicity tests with and without S9. The 50 mg/ml (5% w/v) dose is the usual maximum dose for non-cytotoxic chemicals tested by the BRRC Standard Protocol to avoid possible artefacts produced by non-physiological cell-culture conditions at higher doses.
Remarks on result:
other: all strains/cell types tested
Conclusions:
Interpretation of results (migrated information):
negative

Diethylene glycol was neither genotoxic nor cytotoxic to CHO cells under the conditions of this in vitro test system.
Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Remarks:
Type of genotoxicity: gene mutation
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: well-documented, acceptable study report
Justification for type of information:
Read across is based on the category approach. Please refer to attached category document.
Qualifier:
according to
Guideline:
EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)
GLP compliance:
yes (incl. certificate)
Remarks:
testing lab.
Type of assay:
bacterial reverse mutation assay
Target gene:
S. typhimurium strains
Species / strain / cell type:
other: S. typhimurium strains TA98, TA100, TA1535, TA1537, TA1538
Metabolic activation:
with and without
Metabolic activation system:
rat liver S-9 mix
Test concentrations with justification for top dose:
1 - 111.8 mg/plate
Vehicle / solvent:
sterile, distilled water
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
True negative controls:
yes
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenylenediamine; 9-aminoacridine; sodium azide; 2-aminoanthracene
Details on test system and experimental conditions:
Sample Preparation: The test substance was dissolved in water to a concentration of 300 mg/ml to attain doses of 30 mg/plate and below. All subsequent dilutions were made in the same solvent. Dilutions of the test substance were made fresh each day of testing.
Dose Selection: A preliminary toxicity test was performed using strain TA100 to determine the level of toxicity of the test substance. Ten doses were tested for toxicity with a plate assay performed in the manner used for mutagenicity determinations. Toxicity was assessed at 24 to 48 hours after treatment by either growth inhibition of the background lawn or a reduction in the number of spontaneous mutants.
Testing: The test chemical was tested in triplicate at five doses - chosen to span a range which included moderately toxic to relatively nontoxic concentrations. If the substance was nontoxic in the preliminary toxicity test, 100 ul of liquid or 50 mg of solid was used as the maximum dose, unless limited by solubility. Testing was performed both with and without metabolic activation. Concurrent solvent and positive controls were run in each test.
Metabolic Activation: S9 liver homogenate, prepared from Aroclor 1254-induced, Sprague-Dawley male rats, was purchased from Microbiological Associates. For tests with metabolic activation, 0.5 ml of S9 mix containing 50 ul of S9 was added per plate.
Evaluation criteria:
The spontaneous reversion for the solvent controls should be within this laboratory's historical range. The positive controls should demonstrate that a test systems are responsive with known mutagens. A test chemical is considered to be a bacterial mutagen if the number of revertant colonies is at least twice the solvent control for at least one dose level and there is evidence of a dose-related increase in the number of revertant colonies. If a test chemical produces a marginal or weak response that cannot be reproduced in a second test, the test result will be considered negative. If there is no evidence of a dose-related increase in the number of revertant colonies and the number of revertant colonies is not twice the solvent control, then the test chemical is not considered to be a bacterial mutagen.
Statistics:
no data
Species / strain:
other: S. typhimurium strains TA98, TA100, TA1535, TA1537, TA1538
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
other: > 11.8 mg/plate
Vehicle controls validity:
valid
Untreated negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Diethylene glycol was tested in a preliminary toxicity screen at 111.8, 30, 10, 3, 1, 0 .3, 0 .1, 0 .03, 0 .01, and 0 .003 milligrams per plate with strain TA100 only. None of the doses inhibited growth of the background lawn. Based on these results, mutagenicity testing was done with 5 doses of 111.8, 30, 10, 3, and 1 milligrams per plate in triplicate. The maximum dose of 111.8 mg/plate exceeds the exposure concentration guidelines of the U.S. E.P.A. Health Effects Test Guidelines (HG-Gene Muta-S.typhimurium, August, 1982). No evidence of mutagenicity was observed at any of the tested doses, either by evidence of a dose-response relationship or a doubling of the number of colonies over the solvent control. All strains exhibited a positive mutagenic response with the positive controls tested both with and without S9 metabolic activation. Negative (solvent) controls were also tested with each strain, and the spontaneous reversion rates were within the historical ranges at this laboratory. All positive and negative controls were run concurrently with the test chemical. Concurrently run sterility checks showed that the S9 mix, PBS, the test chemical and all solvents and controls were sterile.
Remarks on result:
other: all strains/cell types tested
Conclusions:
Interpretation of results (migrated information):
negative

Diethylene glycol did not produce a dose-dependent mutagenic response in any of the Salmonella typhimurium strains. Under the conditions of this assay, Diethylene glycol was not mutageníc in the Salmonella /microsome mutagenicíty assay.
Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

In vivo genetic toxicity data are available for diethylene glycol and tetraethylene glycol, components of

the reaction mass of 3,6,9-trioxaundecane-1,11-diol and 2,2'-oxydiethanol and 2,2'-(ethylenedioxy)diethanol and 3,6,9,12-tetraoxatetrade.

Link to relevant study records
Reference
Endpoint:
in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
weight of evidence
Study period:
8 - 11 December 1987
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This study was conducted according to GLP and sufficient data is available for the interpretation of results.
Justification for type of information:
Read across is based on the category approach. Please refer to attached category document.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)
GLP compliance:
yes
Type of assay:
chromosome aberration assay
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
Seventy male and female, 11-12 week old Sprague-Dawley rats were obtained from Harlan Sprague Dawley Inc., Indianapolis, IN. This strain was used because of this laboratory's toxicological experience with Sprague-Dawley rats. For definitive testing, the male rats weighed between 290 g to 326 g and the female rats weighed between 187 g and 220 g at the initiation of the study. The animals were inspected for health upon arrival and were weighed prior to dosing. Only animals which appeared healthy were used for testing following a minimum of a 5-day acclimation period after arrival at the
laboratory. Routine quality control testing was performed on the animals under the direction of the BRRC clinical veterinarian and the animals were found to be healthy. Animals not used for these studies were sacrificed and discarded.

One to five rats/sex/cage were housed in undivided stainless steel Maxi-rack cages with wire-mesh floors under which animal cage board was placed. Prior to testing, all animals were assigned unique animal numbers, weighed and identified with monel ear tags. The animals were randomized and assigned to dosage groups using a stratified design to assure homogeneity of body weights between groups. After randomization, the rats were transferred to clean divided Maxi-tack cages and housed individually in the divided cages until sacrifice. The animals were fed commercial pelleted rodent diet (Agway BMH3000 Certified Rodent Pellets). Food was provided ad libitum until approximately 3:00 pm of the afternoon prior to dosing. Food was replaced 1-3 hr after dosing and provided ad Jibitum until sacrifice. Water was supplied by the Municipal Authority of Westmoreland County (Greensburg, PA) and available ad libitum. The animal room temperature and humidity was controlled and room lights were automatically timed for a 12-hr light/dark cycle. Room temperature and relative humidity were monitored continuously
throughout the the study.
Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
Control Agents:
The sponsor indicated that the test sample was infinitely soluble in water; thus, water was used as the solvent for dilution of the test agent. The volume of the vehicle control substance (water) was administered at an equivalent volume as that used to deliver the test substance (10 ml/kg). Cyclophosphamide (CAS# 6055-19-2) was administered as a single intraperitoneal injection of 30 mg/kg to demonstrate the responsiveness of the animals to a recognized clastogenic agent. Two groups of animals were treated with either the vehicle or the positive control agent. These groups were sacrificed and bone marrow was harvested only at the 24 hour interval after dosing.

Sample Preparation:
Stock dilutions were prepared fresh on the morning of each test day and the accuracy of dilution in definitive tests was verified by gravimetric analysis. Dilutions were prepared to achieve concentrations that would deliver a dosing volume of 10 ml/kg. The sponsor indicated that the sample was stable for at least one year in water and no additional stability or content analyses was performed in the solvent at BRRC.
Duration of treatment / exposure:
Rats were sacrificed 24 hours after dosing with vehicle or positive control agents and 12, 24 or 48 hours after dosing with tetraethylene glycol
Frequency of treatment:
A single dose was administered
Post exposure period:
Rats were sacrificed 24 hours after dosing with vehicle or positive control agents and 12, 24 or 48 hours after dosing with tetraethylene glycol
Remarks:
Doses / Concentrations:
1250, 2500 or 5000 mg/kg
Basis:
actual ingested
No. of animals per sex per dose:
5 males and 5 females/dose level
Control animals:
yes, concurrent vehicle
Positive control(s):
Cyclophosphamide (CAS# 6055-19-2) was administered as a single intraperitoneal injection of 30 mg/kg to demonstrate the responsiveness of the animals to a recognized clastogenic agent.
Tissues and cell types examined:
Bone marrow was examined.

Microscopic evaluation - When possible, 500 cells per animal were scored for proportion of mitotic cells. Reduced numbers of mitotic cells is an indication of cytotoxicity and excessive reduction in number of mitotic cells can preclude cytogenetic evaluation of chromosomes. Fifty metaphase cells were evaluated for incidence and type of chromosome damage for each animal/dose/sample time. Each cell was evaluated for chromosome number, specific type of chromosome- or chromatid-type aberrations and further classified for deletions and exchanges. Gaps, endoreduplicated
chromosomes and polyploid cells were noted and tabulated but are not included as aberrations when computing the proportion of aberrant cells or for use in statistical analyses. Severely damaged cells (>/= 10 breakage events) and pulverized cells were recorded as severely damaged (SD) but no attempt was made to classify the types of damage in these severely damaged cells.
Details of tissue and slide preparation:
Sacrifice and Bone Marrow Extraction
The animals were sacrificed at preassigned time intervals of 12 hr, 24 hr or 48 hr after administration of the dosing material. Colchicine (4 mg/kg) was injected IP 2-3 hours prior to sacrifice. Animals were euthanized by Metofane inhalation and/or cervical dislocation. A femur was removed from each animal and the bone marrow was flushed into a centrifuge tube using 10-15 ml of freshly prepared Hank's Balanced Salt Solution (pH 7.0). The suspension was centrifuged, then the pellet was resuspended in 15 ml of 0.075M KCl (hypotonic) solution and incubated at 37OC for 20-30 minutes. Cells were centrifuged and fixed with 2-3 changes of Carnoy's fixative (3:l methanol; acetic acid). Fixed cells were refrigerated at 4OC at least 12 hours prior to slide preparation. Just prior to preparing slides, cells were centrifuged and resuspended in approximately 1 ml of Carnoy's fixative to achieve an opalescent suspension. To prepare slides, 3-4 drops of the suspension were dropped onto a clean wet slide and air-dried. Slides were identified by BRRC chemical number, animal number and sacrifice interval. Initially, one slide was prepared for each animal. Additional slides were prepared as needed to assure that sufficient numbers of mitotic cells were available. Chromosomes were stained for approximately 10 minutes in a dilute Giemsa solution (1:25). Slides were rinsed with water, dried and coverslipped.
Evaluation criteria:
A positive effect was considered to be a statistically significant and
dose-related increase in the frequency of structural chromosome aberrations.
Alternatively, the production of a statistically significant increase for at least one dose level was considered to be an equivocal effect if there was no evidence of a dose-related response. A test substance which did not produce positive increases as described above was considered to be inactive as an in vivo clastogenic agent in this test system.
Statistics:
Analyses of the test data employed the Fisher's Exact Test (one-tailed) to determine statistical significance of increased incidences of aberrant cells between the test and control populations. This statistical test was considered appropriate for the analysis of the data because it is a distribution independent test and cytogenetic data often vary from a normal distribution required for parametric analyses. The total number of aberrant cells from all animals at each concentration were compared to the respective solvent control value for each sex at each sample time. A difference between treated and control cells was considered to be significant when p p>0.01; b = 0.01 > p > 0.001; c = p < 0.001.
Sex:
male/female
Genotoxicity:
negative
Toxicity:
not examined
Remarks:
Animals were tested at 5000 mg/kg, the highest dose this laboratory will examine.
Vehicle controls validity:
valid
Negative controls validity:
not specified
Positive controls validity:
valid
Additional information on results:
Selection of Dose Levels:
In a limited toxicity test, male and female Sprague-Dawley rats were administered a single peroral dose of 5000 mg/kg of tetraethylene glycol and observed for clinical signs. No mortality or adverse clinical signs were observed, In addition, body weights were obtained at the end of the 5 day observation period and all animals showed weight gains of at least 16 g. Since tetraethylene glycol was demonstrated to be relatively non-toxic, the maximum limit dose (5000 mg/kg) was selected as the highest dose level for definitive testing. Subsequent dose levels of 2500 mg/kg and 1250 mg/kg were selected at intervals of 50% and 25% of the maximum limit dose, respectively.

Evaluation of Potential Chromosome Damage:
Table 1 presents the incidence of chromatid-type and chromosome-type aberrations observed in bone marrow cells of male and female rats obtained 12 hr, 24 hr and 48 hr after dosing, respectively. Relatively low frequencies of simple chromatid breaks and chromosome fragments were the predominant types of damage observed at all three sample periods with both male and female rats.

Table 2 presents a general summary of the overall test results and a statistical summary of the significance of the differences observed. No
statistically significant or dose-related increases in chromosome aberrations above vehicle control values were observed with either male or female rats sacrificed at any of the three time intervals after dosing. Mean incidence of aberrant cells ranged from 1.2% to 5.2% for male rats, and from 0.8% to 4.8% for female rats administered tetraethylene glycol. These incidences are within the typical range of background variability observed for this test system at BRRC .

Animals treated with the positive (cyclophosphamide) and vehicle (water) control agents were evaluated for chromosome damage at the 24 hr sample period. Cyclophosphamide was highly effective in producing significant numbers and types of damage with both male and female rats which demonstrates the responsiveness of the test animals to a known clastogenic agent. The incidence and types of aberrations found in bone marrow cells of rats dosed with the vehicle control were within the expected range of values for this test system consistent with a valid test.

Table 1 Summary of Chromosome Damage: In Vivo Cytogenetic Testing with Bone Marrow Cells of Rats

 Test Material  Mitotic Index (%)  % Aberrant* Cells  Mitotic Index (%)  % Aberrant* Cells
 Tetraethylene glycol, mg/kg     Males       Females
            12 hour values
 1250  4.4 (1.0)  4.4 (2.97)  5.0 (0.8)  2.8 (2.68)
 2500  3.7 (1.4)  2.4 (2.61)  4.3 (2.0)  0.8 (1.10)
 5000  4.5 (1.5)  2.0 (1.41)  4.6 (1.7)  2.8 (2.28)
            24 hour values
 1250  5.3 (0.6)  3.6 (2.19)  3.2 (1.4)  4.8 (4.15)
 2500  4.9 (1.0)  3.6 (3.29)  5.9 (1.4)  3.6 (1.67)
 5000  4.6 (1.2)  3.6 (3.58)  4.9 (0.5)  1.6 (1.67)
 Control (Water)  5.1 (0.3)  3.6 (3.85)  5.4 (1.7)  3.2 (2.68)
 Positive Control (Cyclophasphamide)  2.4 (0.5)  39.2 (4.15)  2.1 (1.2)  36.4 (4.34)
            48 hour value
 1250  4.9 (1.6)  5.2 (3.03)  5.0 (1.5)  2.4 (2.61)
 2500  5.2 (1.0)  1.2 (1.79)  6.5 (2.2)  1.2 (1.79)
 5000  5.0 (1.3)  2.0 (2.00)  5.9 (0.7)  2.8 (2.28)

*A total of 50 cells/animal were evaluated.

Table 2 Tetraethylene Glycol: Summary of Chromosome Aberration Data and Statistical Analyses

 Concentration    Number of  Total Number of  Total Number of  Mean %
 mg/kg  Sex  Animals  Cells Scored  Aberrant Cells Aberrant Cells (+S.D.)* 
 Tetraethylene glycol              12 Hr Sample Period
 1250  M  5  250  22  4.4 (2.97)
   F  5  250  14  2.8 (2.68)
 2500  M  5  250  12  2.4 (2.61)
   F  5  250  4  0.8 (1.10)
 5000  M  5  250  10  2.0 (1.41)
   F  5  250  14  2.8 (2.28)
               24 Hr Sample Period
 1250  M  5  250  18  3.6 (2.19)
   F  5  250  24  4.8 (4.15)
 2500  M  5  250  18  3.6 (3.29)
   F  5  250  18  3.6 (1.67)
 5000  M  5  250  18  3.6 (3.58)
   F  5  250  8  1.6 (1.67)
 Control (Water)  M  5  250  18  3.6 (3.85)
   F  5  250  16  3.2 (2.68)
 Positive Control (Cyclophosphamide)  M  5  250  196  39.2 (4.15)c
   F  5  250  182  36.4 (4.34)c
               48 Hr Sample Period
 1250  M  5  250  26  5.2 (3.03)
   F  5  250  12  2.4 (2.61)
 2500  M  5  250  6  1.2 (1.79)
   F  5  250  6  1.2 (1.79)
 5000  M  5  250  10  2.0 (2.00)
   F  5  250  14  2.8 (2.28)

* Statistical significance above concurrent control values were analysed using the Fisher's Exact Test (1-tailed). c = p < 0.001.

Conclusions:
Interpretation of results (migrated information): negative
Tetraethylene glycol did not produce evidence of statistically significant or dose related increases in incidences of bone marrow cells with chromosome aberrarions in either male or female Sprague Dawley rats. Thus, tetraethylene glycol was not considered to be clastogenic under the conditions of he study.
Executive summary:

Tetraethylene glycol was administered to both male and female Sprague-Dawley rats by a single oral gavage and bone marrow cells were evaluated for potential chromosome damage. Test concentrations were chosen on the basis of a preliminary toxicity test which indicated that tetraethylene glycol was relatively nontoxic up to the maximum concentration of 5000 mg/kg which has been established as the BRRC limit dose for testing relatively nontoxic chemicals in this test system. Thus, three dose levels were tested in the definitive chromosome aberration test at intervals of 100%, 50% and 25% of the maximum dose of 5000 mg/kg.

None of the three dose levels of tetraethylene glycol tested produced statistically significant or dose related increases in relative numbers of chromosome aberrations compared to control values with either male or female Sprague-Dawley rats. Simple chromatid breaks and fragments were the predominant types of aberrations observed and the frequencies of these aberrations were within the range of the spontaneous incidence for this test system at this laboratory. Thus, tetraethylene glycol was not considered to be

clastogenic (chromosome breaking) to Sprague-Dawley rats under the conditions of this vivo test system.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed (negative)

Additional information

Genetic Toxicity in vitro

In key studies, diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (TTEG) have been tested in Ames assays. In an Ames assay with S. typhimurium strains TA98, TA100, TA1535, TA1537, and TA1538, concentrations of 1.0-111.8 mg/plate DEG with and without S9 showed no mutagenic activity (Bushy Run Research Center, 1984a). S. typhimurium strains TA98, TA100, TA1535, and TA1537 were used to test TEG for mutagenic activity at concentrations of 1.0-112.6 mg/plate with and without S9 in an Ames assay by Bushy Run Research Center (1986a). No mutagenic activity was observed. Mutagenicity of TTEG was tested in S. typhimurium strains TA98, TA100, TA1535, TA1537 and TA1538 at concentrations of 1.0-112.6 mg/plate with or without metabolic activation using triplicate cultures at each dose level (Bushy Run Research Center, 1986b). Additional Ames tests performed with DEG (BASF, 2013) and TEG (BASF, 2012) tested at up to 5 mg/plate in S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and E. coli WP2, with and without metabolic activation, similarly showed negative results. Mutagenic activity was not observed in any tester strain with or without metabolic activationwith any of the mixture components. Thus, thereaction mass of 3,6,9-trioxaundecane-1,11-diol and 2,2'-oxydiethanol and 2,2'-(ethylenedioxy)diethanol and 3,6,9,12-tetraoxatetrade is not expected to be mutagenic in any tester strain with or without metabolic activation

In additional key studies, DEG, TEG, and TTEG have been tested in in vitro mammalian chromosome aberration tests. In a study by Bushy Run Research Center (1984b), 50 mg/ml DEG was not genotoxic or cytotoxic to Chinese hamster ovary (CHO) cells when tested with or without metabolic activation. TEG was negative for genotoxic and cytotoxic effects in a mammalian chromosome aberration assay in CHO cells wherein concentrations of 35-50 mg/ml TEG were tested with and without metabolic activation (Bushy Run Research Center, 1986c). TTEG was also negative in the mammalian CHO/HGPRT forward mutation assay at concentrations up to 50 mg/ml (Bushy Run Research Center, 1987).

In supporting studies, sister chromatic exchange (SCE) assays with CHO cells showed negative results at concentrations of 30-50 mg/ml DEG (Bushy Run Research Center, 1984c) and at concentrations up to 50 mg/ml TEG (Bushy Run Research Center, 1986d), with and without metabolic activation.

In a supporting study by Bushy Run Research Center (1987b), a weak response in the chromosome aberration test was seen in cultured CHO cells at concentrations of 24-50 mg/ml, with and without metabolic activation. However, the lowest dose tested in this study was 5x higher than the limit dose recommended by the current guidelines. Moreover, the high osmolality observed in this study (423 to 605 mOsm/kg H2O) is a known confounder in this in vitro cell system. Therefore, this study is not considered appropriate for evaluation of classification of TTEG. TTEG produced chromosome aberrations in Chinese hamster epithelial liver (CHEL) cell line, which reportedly retains sufficient metabolic activation capability, but is not a typical cell line used for genotoxic study battery (Biondi et al., 2002). Positive results were also reported in CHO cells in the presence of metabolic activation in this study, but this result does not agree with the Union Carbide Corporation 1987 Klimisch 1 study. Finally, TTEG produced a weak but statistically significant increase in the incidence of SCEs in CHO cells at 1 to 50 mg/ml with and without metabolic activation; however, there was no dose-response associated with the incidence of SCEs (Bushy Run Research Center, 1987a). Again, the biological significance of these results should be evaluated with caution due to the high range of osmotic concentrations evaluated in the test system.

 

Genetic Toxicity in vivo

In the key study, TTEG was assessed in an in vivo bone marrow chromosome aberration assay in which male and female Sprague-Dawley rats were given doses up to 5000 mg/kg TTEG by gavage (Bushy Run Research Center, 1988). Dose levels of 1250, 2500, and 5000 mg/kg TTEG, chosen on the basis of a preliminary test which indicated that TTEG was relatively nontoxic up to the maximum concentration of 5000 mg/kg, produced no statistically significant or dose related increases in relative number of chromosome aberrations compared to control values with either male or female Sprague Dawley rats. Simple chromatid breaks and fragments were the predominant types of aberrations observed and the frequencies of these aberrations were within the range of the spontaneous incidence for this test system at this laboratory. Thus, TTEG was not considered to be clastogenic to Sprague-Dawley rats under the conditions of this in vivo test system.

 

In a supporting study, an in vivo micronucleus (MN) test was performed in male and female Swiss-Webster mice given doses of 2500, 4000, or 5000 mg/kg TTEG i.p. (Bushy Run Research Center, 1987). No statistically significant difference in micronucleated polychromatic erythrocyte (MNPCE) frequency was observed in the TTEG treated mice at any time point, when compared to the concurrent vehicle controls.

 

Additionally, a supporting MN mouse study (BASF, 2009) showed no increase in PCEs or MNPCEs/mouse after i.p. administration of 500, 1000, or 2000 mg/kg bw DEG to male and female NMRI mice. 

 

TTEG was also negative in a dominant lethal test by Bushy Run Research Center (1993). In this supporting study, male rats were treated for five days with 5000, 25000 or 50000 ppm TTEG in the drinking water and subsequently mated to naïve (untreated) females over ten weeks, with females replaced weekly. TTEG produced evidence of toxicity in males at 50000 ppm and urinary findings consistent with an osmotic diuresis at 25000 and 50000 ppm. However, no indications of subsequent reproductive or gestational effects were observed, including no significant pre-implantation loss over the ten week period. The NOEL for general toxicity was 25000 ppm.

Justification for classification or non-classification

DEG, TEG, and TTEG were not mutagenic in in vitro bacterial test systems. DEG and TEG were also negative in mammalian chromosome aberration and sister chromatic exchange assays. TTEG displayed evidence of clastogenic effects in vitro, but this was with high doses (5x the current guideline maximum dose) confounded by high osmolality which are known clastogenicity inducers. Similarly, increased incidence of SCE after TTEG exposure occurred under conditions of high osmolality. In vivo MN studies with TTEG, however, produced no clastogenic effects in male or female Swiss-Webster mice or Sprague-Dawley rats and TTEG was negative in the dominant lethal test. Similarly, DEG also did not produce increased MN in vivo. Based on these component data, genetic toxicity is not expected for the reaction mass of 3,6,9-trioxaundecane-1,11-diol and 2,2'-oxydiethanol and 2,2'-(ethylenedioxy)diethanol and 3,6,9,12-tetraoxatetrade.