2-isopropoxyethanol

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

sub-chronic toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1976

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-guideline non-GLP study but with adequate and well described methods and results from an original study report.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1976

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Follows the basic principles of an OECD 413 guideline study. Not all end points examined.

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-isopropoxyethanol

EC Number:

203-685-6

EC Name:

2-isopropoxyethanol

Cas Number:

109-59-1

Molecular formula:

C5H12O2

IUPAC Name:

Propan-2-ol

Details on test material:

- Name of test material (as cited in study report): isopropyl oxitol
- Lot/batch No.: 740731

Test animals

Species:

rat

Strain:

other: CFE (Carworth Farm E-strain)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Tunstall Laboratory (bred under specific pathogen-free conditions)
- Age at study initiation: 12-13 weeks
- Housing: 4animals/cage, 40animals/chamber
- Diet: food was removed before every exposure
- Water: ad libitum
- Acclimation period: 3 weeks
ENVIRONMENTAL CONDITIONS
- Temperature (°C): temperature of the air supply to the chambers was maintained at 65 +/- 2 degree F

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: 10 m3 stainless steel inhalation chamber
- Method of conditioning air:
- Source and rate of air: Air was drawn from the main body of the laboratory in which the chambers were located by independent centrifugal fans mounted in the exit ducts from the chambers, preventing any leakage of the test atmospheres into the laboratory.
- System of generating particulates/aerosols: The test atmospheres were generated by vaporizing the solvent in an induced air flow to produce a concentrated vapor/air mixture which was then diluted to the desired concentration by the main air flow into the chamber. The vaporizer was a quartz-sheathed heating element wound with glass fiber tape to increase the surface area, and the solvent was fed onto this surface from a solvent reservoir by means of a micrometering pump.
- Temperature, humidity, pressure in air chamber: temperature of the air supply to the chambers was maintained at 65 +/- 2 degree F
- Air flow rate: Top dose chamber = 3.5 m3 min-1 ; three other chambers = 4.3 m3 min-1

TEST ATMOSPHERE
- Brief description of analytical method used: Two different analysis systems were used in this experiment.
One system, which was two Beckman 109A Total Hydrocarbon analysers, enabled a continuous monitoring of the test atmospheres to be carried out during the exposure period. These analysers quickly responded to changes made in the atmosphere generation system and/or total chamber air flow rate, so that adjustments could be made to maintain the desired concentration of toxicant in the test atmospheres. This was particularly useful during the start-up period.
The other system consisted of a Beckman GC 2A gas chromatograph fitted with a flame ionisation detector and an auto gas sampling valve. Test atmosphere from each of the three chambers in turn was drawn continuously through the gas sampling system, and a sample was transferred to the column every 6 min. The peak heights were averaged over the sampling period of approximately 75 min. The instrument was calibrated by means of an exponential dilution technique using a 12.5 liter stirred gas flask.
- Samples taken from breathing zone: yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The three test atmospheres were analyzed during the daily exposure period on both of the analysis systems, so that while continuous signals were obtained from the two Total Hydrocarbon analysers for two of the test atmospheres, the third atmosphere was being repeatedly chromatographed on the Beckman GC 2A. In this way, the concentrations of the solvent in the three test atmospheres could be determined, and any deviations from the desired values could be quickly spotted. The mean concentrations and ranges of solvent in the test atmospheres over the complete exposure period were 24 (16 to 30) ppm (v/v), 47 (32 to 56 ) ppm (v/v), and 197 (169 to 230 ) ppm (v/v).

Duration of treatment / exposure:

26 weeks

Frequency of treatment:

6hours/day, five days /week

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 25, 50, 200 ppm
Basis:
nominal conc.

No. of animals per sex per dose:

40 animals/sex/dose

Control animals:

yes

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily

DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
- Time schedule for examinations: Week 0, 1, 2, 9, 10, 12, 18, 21, 23, 26

FOOD CONSUMPTION:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Week 0, 5, 9, 13, 18, 22, 26
- Anaesthetic used for blood collection: No data. Randomly selected rats were killed to provide blood samples by cardiac puncture
- Animals fasted: No data
- How many animals: week 0 = 12animals/sex/dose, week 5, 9, 13, 18, 22 = 3animals/sex/dose, week 26 = 22animals/sex/dose
- Parameters: Hb, PCV, RBC, WBC, MCV, MCH, MCHC, PT (prothrombin time), KCCT (kaolin cephalin coagulation time), Osmotic fragilities

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Week 0, 5, 9, 13, 18, 22, 26
- Animals fasted: No data
- How many animals: week 0 = 12animals/sex/dose, week 5, 9, 13, 18, 22 = 3animals/sex/dose, week 26 = 22animals/sex/dose
- Parameters : Protein, urea, ALP (Alkaline phosphatase), SGPT (Serum glutamic pyruvic transaminase), SGOT (Serum glutamic oxaloacetic transaminase), Na, K, Cl

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
The following organs were weighed at necropsy: brain, heart, liver, spleen, kidneys, testes.

HISTOPATHOLOGY: Yes
The following were examined: brain, heart, kidney, lung, spleen, liver, alimentary tract, pancreas, salivary gland, thymus, mesenteric lymph node, gonads, prostate or uterus, pituitary, adrenals, larynx, thyroid, eye and decalcified sections of nasal cavities.

Statistics:

Body weights and organ weights were analyzed by covariance analysis using initial body weight as the covariate.Reported means were adjusted for initial body weight if a significant covariance relationship existed. Where no significant covariance relationship existed, means were reported unadjusted. Covariance analysis was also used with terminal body weight as the covariance to test whether organ weight differences could be attributed to the differences in terminal body weight or if differences in organ weight were concealed by body weight variation. Reported means were adjusted for terminal body weight if a significant covariance relationship existed. This is not a true covariance analysis since terminal body weight are dependent upon treatment and has only been reported when it aids the interpretation of body and organ weight difference.Clinical chemical and hematological parameters were examined using analysis of variance.The significance of any differences between treatment and control group means was tested using the Williams t-test.However, on some occasions a monotonic dose response relationship could not be assumed, in which case Dunnett’s test was used.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
No test substance related effects were observed.

BODY WEIGHT AND WEIGHT GAIN
No test substance related effects were observed.

HAEMATOLOGY
At 200 ppm a consistent and significant reduction in hemoglobin concentration was observed in male and female rats. This was accompanied by marginal reduction in packed cell volume and a consistently lower erythrocyte count. A consistent and significant elevated mean cell volume in the male and female rats exposed to 200 ppm isopropyl OXITOL was also noted. Small and inconsistent rises in erythrocyte counts occurred in both male and female rats. Changes in the osmotic fragility of rat erythrocytes occurred on occasions at all exposure levels (Table 1).At 25 ppm exposure level the 50% osmotic fragility was only statistically significant at week 22 in male rats and at week 13 and week 18 in female rats. No differences between control and 25 ppm treatment group were found at week 26, the end of the study.

CLINICAL CHEMISTRY
Significant decrease in plasma potassium was observed in both rats sexes in the 25, 50 and 200 ppm groups at week 26. The significance of this is not clear.

ORGAN WEIGHTS
Significant increase in the spleen weights were observed in male and female rats in the 200 ppm group.Significant increase in heart weight and decrease in liver weight were observed in male rats in the 200 ppm group.

GROSS PATHOLOGY
No test substance related effects were observed.

HISTOPATHOLOGY: NON-NEOPLASTIC
Amounts of brown pigment in kupffer cells of the liver in female rats in the 200 ppm group.Excessive amounts of hemosiderin in the red and white pulp of the spleen in male and female rats in the 50 ppm and 200 ppm groups.Extramedullary hematopoiesis was observed in the spleen of rats in the 200 ppm group.Small amounts of lipid in the liver parenchyma were observed in male rats in the 200 ppm group.

Effect levels

1

Dose descriptor:

LOAEL

Effect level:

25 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Changes in osmotic fragility of erythrocytes

2

Dose descriptor:

NOAEC

Effect level:

100 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Primary and secondary effects not related to haemolysis

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Table-1. Osmotic fragilities of erythrocytes in rats.

Week No.	Atomosphere concentration ppm			Male					Female
		No. of rats	Osmotic fragilities % NaCl producing hemolysis				No. of rats	Osmotic fragilities % NaCl producing hemolysis
			0%	50%	100%			0%	50%	100%
0	0	3	0.611	0.403	0.213		3	0.620	0.441	0.283
	25	3	0.611	0.389	0.233		3	0.623	0.444	0.210*
	50	3	0.622	0.393	0.200		3	0.662	0.443	0.210*
	200	3	0.590	0.390	0.200		3	0.655	0.443	0.230
	Standard deviation of a single observation		0.0251	0.0162	0.0115			0.0288	0.0126	0.0329
5	0	2	0.720	0.47.	0.230		3	0.608	0.463	0.248
	25	3	0.632	0.455	0.203		3	0.713**	0.490	0.217
	50	3	0.695	0.460	0.195		3	0.708**	0.505*	0.255
	200	3	0.760	0.515*	0.257		3	0.799**	0.550**	0.171**
	Standard deviation of a single observation		0.0425	0.0148	0.0230			0.0231	0.0159	0.0266
9	0	3	0.662	0.382	0.173		3	0.677	0.433	0.190
	25	3	0.732	0.383	0.135		3	0.697	0.431	0.158
	50	3	0.730	0.407	0.179		2	0.760**	0.450	0.180
	200	3	0.722	0.463**	0.175		3	0.767**	0.523**	0.190
	Standard deviation of a single observation		0.0421	0.0187	0.0309			0.0149	0.0296	0.0353
13	0	3	0.660	0.369	0.117		3	0.653	0.402	0.145
	25	3	0.665	0.427	0.160		3	0.707	0.428*	0.165
	50	3	0.682	0.427	0.128		3	0.730*	0.437*	0.150
	200	3	0.717	0.473**	0.160*		3	0.774**	0.507**	0.167
	Standard deviation of a single observation		0.0307	0.0304	0.0203			0.0303	0.0131	0.322
18	0	2	0.645	0.350	0.113		1	0.661	0.390	0.160
	25	3	0.673	0.397	0.118		3	0.663	0.423**	0.150
	50	3	0.657	0.398	0.130		3	0.643	0.443**	0.153
	200	3	0.713*	0.467**	0.114		3	0.750*	0.493**	0.150
	Standard deviation of a single observation		0.0246	0.0339	0.0198			0.735	0.528	0.188
22	0	3	0.660	0.375	0.193		3	0.662	0.420	0.157
	25	3	0.700	0.433*	0.163		3	0.663	0.407	0.168
	50	3	0.725**	0.428*	0.210		3	0.715	0.448	0.227*
	200	3	0.744**	0.480**	0.178		3	0.735*	0.528**	0.188*
	Standard deviation of a single observation		0.0254	0.0256	0.0349			0.0339	0.0336	0.0259
26	0	22	0.694	0.398	0.284		3	0.671	0.396	0.266
	25	22	0.708	0.400	0.274		3	0.723	0.420	0.266
	50	22	0.726**	0.431**	0.306**		3	0.722	0.452**	0.307
	200	22	0.754**	0.478**	0.317**		3	0.747**	0.488**	0.289
	Standard deviation of a single observation		0.0361	0.0223	0.0218			0.0924	0.0565	0.0515

*: p <0.05, **:p<0.01

Applicant's summary and conclusion

Conclusions:

Hemolytic effects occurred marginally at 25 ppm and clearly at 50 ppm and 200 ppm.The osmotic fragility of the erythrocytes of rats was significantly changed at 25, 50 and 200 ppm.

Executive summary:

Ethylene glycol isopropyl ether was studied for subchronic inhalation toxicity in rats at concentrations of 0, 25, 50, or 200 ppm for 26 week, 6 h/day, 5 day/week. Haemolytic effects occurred marginally at 25 ppm and clearly at 50 ppm and 200 ppm.The osmotic fragility of the erythrocytes was significantly changed at 25, 50 and 200 ppm. Changes not associated as primary or secondary effects of haemolysis were only observed at 200ppm (changes in heart and liver weight).