Propane-1,3-diol

Endpoint summary

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Reliability assigned by ACC in HPV Document

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OTS 798.2650 (90-Day Oral Toxicity in Rodents)

Deviations:

no

GLP compliance:

yes

Species:

rat

Strain:

other: Crl:CD(SD)BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 6 weeks
- Weight at study initiation: 160-201 g for mlaes; 138-158 g for females
- Fasting period before study: None
- Housing: Individually in wire-mesh cages suspended over cage board
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 12 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 72±4°F
- Humidity (%): 30-70%
- Air changes (per hr): Not reported
- Photoperiod (hrs dark / hrs light): 12 hrs light/12 hrs dark

Route of administration:

oral: gavage

Vehicle:

other: deionized water

Details on oral exposure:

Crl:CD (SD) BR rats (10/sex/group) were administered 1,3-propanediol by oral gavage daily for 91 or 92 days at concentrations of 100, 300 and 1000 mg/kg/day. A concurrent control group (10/sex) was administered the vehicle, deionized water. The dose volume for all groups was 10 mL/kg.

PREPARATION OF DOSING SOLUTIONS: The appropriate amount of test substance was weighed into a precalibrated, labeled container and deionized water added to the calibration mark. The preparations were continuously throughout the dispensation and dosing procedures using magnetic stir bars and plates. The dosing solutions, including the vehicle, were prepared weekly and were stored refrigerated until dispensation.

Individual doses were adjusted weekly based on the most recent body weights.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Prior to the study, 10-mL samples were collected from the middle stratum of the low- and high-dose formulations, and stability was determined at 0, 1, 8, and 15 days. During the study samples for concentration verification were collected from the middle of each dosing formulation for the first 4 weeks of dosing and monthly thereafter.

Samples were analyzed via gas chromatography with FID (flame ionization detection).

One and 10% concentrations of 1,3-propanediol in water were stable for up to 15 days. Dosing solutions were generally within 20% of nominal at the 10 mg/mL concentration and within 4% at the 30 and 100 mg/mL concentrations.

Duration of treatment / exposure:

91-92 days

Frequency of treatment:

Daily

Dose / conc.:

100 mg/kg bw/day (actual dose received)

Dose / conc.:

300 mg/kg bw/day (actual dose received)

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

10/sex/group

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Doses were selected based on the results of a 14-day gavage study in rats in which no adverse effects were seen at doses up to 1000 mg/kg (see DO.K1.14D.R.ACC-IUCLID4.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: The animals were observed twice daily for mortality and moribundity.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Clinical observations were performed daily at the time of dosing and 1-2 hours post-dose. Detailed clinical observations were performed weekly and prior to euthanization.

BODY WEIGHT: Yes
- Time schedule for examinations: Weekly

FOOD CONSUMPTION: Yes
- Time schedule for examinations: Weekly

FOOD EFFICIENCY: No data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule: Ophthalmologic examinations were conducted prior to study initiation and termination.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Week 4 and at scheduled necropsy
- Anaesthetic used for blood collection: No data
- Animals fasted: Yes
- How many animals: 10/group
- Parameters checked: The following hematological parameters were measured: total leukocyte count, erythrocyte count, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelet count, prothrombin time, activated partial prothrombin time and the differential leukocyte count (% and absolute) of neutrophils, lymphocytes, monocytes, eosinophils and basophils.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Week 4 and at scheduled necropsy
- Animals fasted: Yes
- How many animals: 10/group
- Parameters checked: The following serum chemistry parameters were measured: albumin, total protein, globulin, albumin/globulin ratio, total bilirubin, urea nitrogen, creatinine, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, gamma glutamyltransferase, glucose, total cholesterol, calcium, chloride, phosphorus, potassium and sodium.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes

Complete necropsies were performed on all animals that survived to scheduled termination. The following organs were weighed: adrenals, brain, epididymides, kidneys, liver, ovaries (with oviducts), pituitary, prostate, seminal vesicles with coagulating glands, testes and thyroid.

HISTOPATHOLOGY: Yes

The following tissues and organs were collected and preserved appropriately: adrenals, aorta, bone with marrow (sternebrae), bone marrow smear from femur, brain (forebrain, midbrain and hindbrain), coagulating gland, epididymis (right), eyes with optic nerve, gastrointestinal tract (esophagus, stomach, duodenum, jejunum, ileum, cecum, colon and rectum), heart, kidneys, liver (sections of 2 lobes), lungs (with bronchi and fixed), mesenteric and submandibular lymph nodes, mammary glands (females only), ovaries with oviducts, pancreas, peripheral nerve (sciatic), pituitary, prostate, submaxillary salivary glands, seminal vesicles, skeletal muscle (vastus medialis), skin, spinal cord (cervical, midthoracic, lumbar), spleen, testis (right), thymus, thyroid (with parathyroids, if present), trachea, urinary bladder, uterus with vagina, vas deferens and all gross lesions. After fixation, these tissues were trimmed, sectioned and examined microscopically for all of the animals in the control and high dose groups. Also, the lungs, liver, kidneys, stomach and testes were examined microscopically from all animals in every group.

Other examinations:

Spermatogenic endpoints were evaluated for all males at study termination. See Reproduction Section (7.8) for details.

Statistics:

All data analyses were conducted using two-tailed tests, p < 0.01 and p < 0.05, comparing the treated groups to the control group by sex. Standard deviations were calculated for all means. Body weight, body weight change, food consumption, clinical pathology, absolute and relative organ weight data were subjected to a one-way analysis of variance, followed by Dunnett's test. Clinical laboratory values for leukocytes that occur at a low incidence (monocytes, eosinophils and basophils) were not subjected to statistical analysis. In addition, the statistical analysis was not performed if the number of animals was 2 or less. All statistical tests were performed by a computer with appropriate programming.

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean body weights and body weight gains were unaffected at all dose levels. A statistically significant increase in mean body weight gain for the 300 mg/kg/day group males during Week 6-7 was attributed to the substantial body weight gain of 42 g for a single animal.

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Description (incidence and severity):

There were several statistically significant differences noted in white blood cell parameters in the treatment groups as compared to the control group. See Table 1. Mean white blood cell and/or lymphocyte counts for all treated males were decreased at the Week 4 interval. However, the differences were attributed to high control group values and not test article administration. At the Week 13 interval, the mean absolute lymphocyte value was increased in the females treated at 1000 mg/kg/day; however, this value was similar to the value for this group at the Week 4 interval and a similar increase was not seen in the males in this treatment group. As no relationship to treatment was established for these differences, no treatment-related hematological changes were observed for any of the treatment groups at either interval.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

Comparison of collected serum chemistry values at both intervals identified some statistically significant differences for the female treatment groups as compared to the control group. See Table 2. At Week 4, decreases were observed in mean aspartate aminotransferase (AAT) at 300 and 1000 mg/kg/day (statistically significant only in females), in mean cholesterol in females at 100 mg/kg/day and in mean chloride at 1000 mg/kg/day in females. Mean glucose was increased at all dose levels but statistically significant in females only. In general these parameters are highly variable and all differences from the control group were slight and/or not present in a dose-related manner. At Week 13, total bilirubin was decreased in females at 100 and 1000 mg/kg/day; however, slight decreases in bilirubin are not usually considered toxicologically significant. There were no other notable differences in the serum chemistry parameters examined; and none of the noted differences are considered to be treatment-related.

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Description (incidence and severity):

Findings in the treated groups were limited to one or two animals in various groups, occurred similarly in the control group and/or were findings commonly observed in laboratory rats.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

Findings in the treated groups were limited to one or two animals in various groups, occurred similarly in the control group and/or were findings commonly observed in laboratory rats.

Other effects:

no effects observed

Description (incidence and severity):

Spermatogenic endpoints were evaluated for all males at study termination. No treatment-related effects on spermatogenic endpoints were observed at any dose level. See Section 7.8.1 for results.

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Basis for effect level:

other: no adverse effects noted at highest dose level tested

Dose descriptor:

LOAEL

Effect level:

> 1 000 mg/kg bw/day (actual dose received)

Basis for effect level:

other: no adverse effects noted at highest dose level tested

Critical effects observed:

no

Table 1:

Hematology Parameter	Males (mg/kg/day)				Females (mg/kg/day)
	0	100	300	1000	0	100	300	1000
Week 4 White Blood Cells (thous/µL)	18.2	14.1*	13.3^	14.4*	10.0	9.3	8.9	11.9
Week 4 Lymphocyte Count (thous/uL)	14.4	11.0*	10.2^	11.3	7.5	7.3	6.9	9.6
Week 13 Lymphocyte Count (thous/uL)	11.0	9.8	9.9	10.7	7.7	9.4	7.0	9.6*

* p< 0.05; ^ p< 0.01

Table 2

Serum Chemistry Parameter	Males (mg/kg/day)				Females (mg/kg/day)
	0	100	300	1000	0	100	300	1000
Week 4 AAT (U/L)	104	91	87	98	113	98	90^	87^
Week 4 Cholesterol (mg/dL)	53	53	48	47	68	52^	63	63
Week 4 Chloride (mEq/L)	101	101	100	100	103	103	103	100^
Week 4 Glucose (mg/dL)	115	120	121	121	103	117*	119*	118*
Week 13 Total Biliruben (mg/dL)	0.1	0.1	0.1	0.1	0.3	0.2*	0.2	0.2*

* p< 0.05; ^ p< 0.01

Conclusions:

NOAEL: 1000 mg/kg (highest dose tested)

Executive summary:

Crl:CD (SD) BR rats (10/sex/group) were administered 1,3-propanediol by oral gavage daily for 91 or 92 days at concentrations of 100, 300 and 1000 mg/kg/day. A concurrent control group (10/sex) was administered the vehicle, deionized water. Clinical observations were performed daily at the time of dosing and 1-2 hours post-dose. Detailed clinical observations were performed weekly and prior to euthanization. Individual body weights and food consumption were recorded weekly. A final fasted body weight was recorded on the day of scheduled termination. Clinical pathology parameters, hematology and serum chemistry, were evaluated once during the dosing period at Week 4 and at scheduled necropsy.  Complete necropsies were performed on all animals that survived to scheduled termination. Histopathology evaluations were performed.

The NOEL of orally administered 1,3-propanediol under the conditions of this study was determined to be 1000 mg/kg/day (the highest dose tested).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

PDO from chemical process.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)

Deviations:

yes

Remarks:

Only 9 days of exposure. Highest dose did not induce toxicity.

GLP compliance:

yes

Remarks:

Two deviations noted deemed not to affect study validity. The test substance was characterized at a non-GLP-compliant lab, and expired hematology analytical control material was used during clinical laboratory analyses.

Species:

rat

Strain:

other: Crl:CD(SD)IGS BR

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc.
- Age at study initiation: 8 weeks
- Weight at study initiation: 235 to 272 grams
- Fasting period before study: No fasting period before the study
- Housing: Rats were housed either singly or in pairs in suspended, stainless steel, wire-mesh cages.
- Diet: PMI Nutrition International, Inc. Certified Rodent LabDiet 5002, ad libitum
- Water: Tap water from United Water Delaware, ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23±1
- Humidity (%): 50±10
- Air changes (per hr): Air flow was 25 L/min.
- Photoperiod (hrs dark / hrs light): 12-hour dark/12-hour light

Route of administration:

other: inhalation: vapor/aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: air

Remarks on MMAD:

MMAD / GSD: MMAD of the aerosol in the intermediate- and high-level concentrations chambers was 2.2 to 2.4 µm and >99% of the particles were less than 10 µm. The GSD was 1.6.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Low-level chamber test atmospheres were generated by metering the liquid test substance into a glass, heated flask with a Harvard Apparatus model 22 Syringe Infusion Pump. Intermediate and high-level chamber test atmospheres were generated by metering the liquid test substance into a Spraying Systems nebulizer with a Harvard Apparatus model 22 Syringe Infusion Pump.
- Method of holding animals in test chamber: Individually restrained in polycarbonate cylinders with conical nose pieces.
- Source and rate of air: Preheated, houseline air - metered with a Brooks model 5850E mass flow controller
- Method of conditioning air: Airflow, temperature, and relative humidity were monitored continually with a Camile Inhalation Toxicology Automated Data System (CITADS) and recorded at 15-minute intervals during each exposure. Chamber oxygen concentration was targeted to at least 19% . Chamber oxygen concentration was measured with a Biosystems model 3100R Oxygen Analyzer and was recorded twice during each exposure.
- System of generating particulates/aerosols: Low-level chambers were generated by metering the liquid test substance into a glass, heated flask. Intermediate and high-level chambers were generated by metering the liquid test substance into a Spraying Systems nebulizer.
- Temperature, humidity, pressure in air chamber: Test chambers = 25 - 28°C, 36- 53% ,Control chamber = 27°C, 42 - 58%
- Air flow: 23 - 25 L/min
- Air change rate: 12 air changes per hour
- Method of particle size determination: Samples to determine particle size distribution (MMAD, GSD, and percent particles less than 1, 3, and 10 µm) were taken 2 times during the study from the intermediate and high-level chambers. Particle size distribution was determined with a Sierra Series 210 Cyclone Preseparator/Cascade Impactor and Sierra Series 110 Constant Flow Air Sampler. An attempt was made to collect a particle size sample from the low-level chamber, but due to the lack of an appreciable aerosol component, particle size calculations were unable to be performed.
- Treatment of exhaust air: Exhaust from each of the test chambers was discharged through a water-filled scrubber followed by an MSA charcoal/HEPA Filter cartridge prior to discharge into the fume hood.

TEST ATMOSPHERE
- Brief description of analytical method used: The atmospheric concentration of vapor was determined by gas chromatography. Aliquots of the impinger solution were injected on a Restek RTX-1 column in a Hewlett-Packard model 5890Z gas chromatograph equipped with a flame ionization detector. The atmospheric concentration of the vapor component was determined by comparing the detector response of the impinger samples to that of the liquid standards with the use of standard curves. Standards were prepared on a daily basis by the quantitative dilution of the test substance in ethanol. No evidence of test substance instability was observed using the methods of test atmosphere generation by gas chromatography.
- Samples taken from breathing zone: Yes

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Known volumes of chamber atmosphere were drawn from the breathing zone of the rats through a sampling train consisting of a preweighed Gelman glass fiber (Type A/E) filter followed by a single, midget, glass impinger that contained ethanol as the collection medium; impinger collection efficiency exceeded 99%. The filters were weighed on a Cahn model C-31 Microbalance. The atmospheric concentration of aerosol was calculated from the difference in the pre-and post-sampling filter weights divided by the volume of chamber atmosphere sampled.

The atmospheric concentration of vapor was determined by gas chromatography. Aliquots of the impinger solution were injected on a Restek TR-1 column in a Hewlett-Packard model 5890A gas chromatograph equipped with a flame ionization detector. The atmospheric concentration of the vapor component was determined by comparing the detector response of the impinger samples to that of liquid standards with the use of standard curves. Standards were prepared on a daily basis by the quantitative dilution of the test substance in ethanol.

Duration of treatment / exposure:

6 hours per day

Frequency of treatment:

9 exposures (excluding weekends) over a 2-week period

No. of animals per sex per dose:

10 male rats/dose group. Five rats/group were sacrificed at the end of the exposure period. Five rats/group were given a 18-day recovery period

Control animals:

yes

Details on study design:

- Dose selection rationale: High concentration was selected on the basis of rangefinding exposures conducted during methods development. 6 Male rats exposed to 1700 mg/m3 for 5 to 6 hours per day for four days resulted in lung noise in several animals but no gross pathological findings.
- Rationale for animal assignment (if not random): Computerized, stratified, randomization program so that mean body weights per group were similar.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes (Twice daily)

DETAILED CLINICAL OBSERVATIONS: Yes
- All rats were individually observed for clinical signs before and after each exposure. Group clinical observations were made during exposures. During the recovery period, all rats were observed daily.

BODY WEIGHT: Yes
- Time schedule for examinations: During the exposure phase of the study, all rats were weighed daily (except on weekends). During the recovery period, all remaining rats were weighed at least twice per week.

FOOD CONSUMPTION: No

FOOD EFFICIENCY: No

WATER CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: On the day following the last exposure
- Anaesthetic used for blood collection: Yes - under light carbon dioxide anesthesia
- Animals fasted: Yes after an approximate 16-hour fast
- How many animals: 4 groups of 10 male rats
- Parameters examined. red blood cell count (RBC), white blood cell count (WBC), platelet count (PLT), hemoglobin concentration (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), neutrophil count (Neut), ban neutrophil count (Band), lymphocyte count (Lymph), atypical lymphocyte count (Alym), monocyte count (Mono), eosinophil count (Eosin), basophil count (Baso)

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: On the day following the last exposure
- Animals fasted: Yes after an approximate 16-hour fast
- How many animals: 4 groups of 10 male rats
- Parameters examined: alklaline phosphatase activity (ALP), alanine aminotransferase activity (ALT), aspartate aminotransferase activity (AST), sorbitol dehydrogenase (SDH), bilirubin concentration (BILRN), cholesterol concentration (CHOL), total protein concentration (TPROT), albumin concentration (ALBMN), globulin concentration (GLOBN), glucose concentration (GLUCO), urea nitrogen concentration (BUN), creatinine concentration (CREAT), phosphate concentration (PHOS), calcium concentration (CALC), sodium concentration (Na), potassium concentration (K), chloride concentration (Cl)

URINALYSIS: Yes
- Time schedule for collection of urine: One day prior to each bleeding time, an overnight (approximately 16-hour) urine specimen was collected.
- Metabolism cages used for collection of urine: No data
- Animals fasted: Yes after an approximate 16-hour fast
- Parameters examined: volume ( VOL), osmolality (OSMOL), urobilinogen (UROBL), pH, hemoglobin or occult blood (BLOOD), glucose, protein, bilirubin, ketone (acetoacetic acid)

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes. The liver, kidneys, lungs, and brain were weighed at necropsy. Each rat was given a complete gross examination and representative samples of the following tissues were saved: liver, kidneys, lungs, heart, spleen, thymus, brain (cerebrum, midbrain, cerebellum, medulla/pons), spinal cord (cervical, thoracic, lumbar), stomach, duodenum, jejunum, ileum, pancreas, cecum, colon, rectum, mesenteric lymph node, adrenal glands, sciatic nerve, thyroid gland, parathyroid glands, trachea, esophagus, pharynx/larynx, sternum (with bone marrow), eyes, urinary bladder, prostate, seminal vesicles, testes, epididymides, nose, and gross lesions. All tissues were fixed in 10% neutral buffered formalin except for eyes, testes, and epididymides which were fixed in Bouin's solution. All tissues from control and high-level rats sacrificed after the 9th exposure were examined microscopically.

HISTOPATHOLOGY: Yes
Nose, pharynx/larynx, lungs, liver, kidneys, testes, and gross lesions were processed and examined microscopically for the low- and intermediate-level groups after the last exposure and for the control and high-level groups after the recovery sacrifice. Processed tissues were embedded in paraffin, cut at a nominal thickness of five micrometers, stained with hematoxylin and eosin, and examined with a light microscope.

Statistics:

Descriptive statistics including mean, standard deviation, and standard error of the mean were used to summarize experimental data.

Parametric or nonparametric pairwise comparisons between test and control groups were used to analyze mean body weights, body weight gains, and clinical laboratory data. Levene's test for homogeneity of variances and the Shapiro-Wilk test for normality were performed to determine which pairwise method of analysis was used to analyze clinical pathology data. When the Shapiro-Wilk test was not significant, the data were analyzed by a one-way analysis of variance (ANOVA) and pairwise comparisons between test and control groups made with Dunnett's test. If the Shapiro-Wilk test was not significant but Levene's test was significant, a robust version of Dunnett's test was used. When the Shapiro-Wilk test was significant, the data were analyzed with the Kruskal-Wallis test and pairwise comparisons between test and control groups made with Dunn's test.

Mean final body weights, and mean absolute and relative (to body weight and to brain weight) organ weights were statistically analyzed with ANOVA. When the value of the F-statistic for differences among groups was significant, pairwise comparisons between treated and control groups were made with Dunnett's test.

The Bartlett's test for homogeneity of variances was performed on organ weight data, and, if significant, was followed by nonparametric procedures.

Final body weights were used for determination of organ to body weight ratios. These body weights, determined just prior to necropsy, were not used to assess the effects of the test substance on body weights ( in-life data was used for this purpose).

Except for the Bartlett's test (p < 0.005), all significance was judged at p < 0.05.

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:

no effects observed

Description (incidence and severity):

No compound-related hematology changes occurred during this study. Some statistically significant hematology findings occurred, but they were considered not to be compound-related for the following reasons: 1) decreased hemoglobin in the high level recovery group was small and similar changes were not present in groups sacrificed at the end of the exposure period, 2) a statistically significant decrease in MCH in the low level group sacrificed at the end of exposure was very small, did not occur in a dose-related manner, and was not associated with compound-related changes in any other hematology parameter, and 3) a statistically significant increase in PLT in the high level recovery group was very small, and a similar change was not present in any treated group sacrificed at the end of the exposure period.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

No compound-related clinical chemistry changes occurred during this study. Some statistically significant clinical chemistry findings occurred, but they were considered not to be compound-related for the following reasons: 1) decreased SDH in the high level was not considered relevant as it is increases in this enzyme that are biologically important, 2) decreases in ALB, and the associated decreases in TP, in the intermediate and high level recovery groups were small and not associated with similar changes in treated groups sacrificed at the end of the exposure period, 3) and increases in Cl in all treated groups sacrificed at the end of the exposure period, and in the intermediate and high level recovery groups, were small, not dose-related, and not associated with changes in other electrolytes.

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

Results of Bartlett's test indicated that parametric procedures were appropriate for analysis of all organs weighed. No statistically or biologically significant changes in organ weight occurred in rats exposed to the test substance.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No gross changes attributable to exposure to the test substance were observed in study rats. Gross observations noted for rats were nonspecific and incidental and are routinely observed in rats of this strain and age.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

Microscopic observations noted for rats were nonspecific and incidental and are routinely observed in rats of this strain and age.

Dose descriptor:

NOEL

Effect level:

1 800 mg/m³ air (analytical)

Sex:

male

Remarks on result:

other: highest concentration tested

Critical effects observed:

no

The analytically determined mean concentrations as measured in the exposure chambers were:

41 ± 1.7 mg/m3

650 ± 8.6 mg/m3

1800 ± 27 mg/m3

Conclusions:

There were no test substance-related mortalities in the study. No toxicologically important changes in clinical pathology, pathology, or in-life animal measurement parameters occurred in any group. The no-observed-effect level (NOEL) for this study is defined as the highest dose at which toxicologically adverse effects attributed to the test substance were not detected. Under the conditions of this study, the NOEL for repeated inhalation exposure in male rats was considered to be 1800 mg/m3, the highest concentration tested.

Executive summary:

Three groups of 10 male rats each were exposed by inhalation to either vapor or a vapor/aerosol mixture of the test substance in air at concentrations targeted to 60, 600, or 1800 mg/m³ for 6 hours/day, 4 or 5 days/week for a total of 9 exposures. A procedural control group of 10 male rats was simultaneously to air only. Rats were weighed prior to each exposure and were observed for clinical signs prior to, during, and following each exposure. At the end of the exposure period, clinical pathology evaluations were conducted on 10 rats/group, and 5 rats/group were sacrificed and necropsied. At the end of the 18-day recovery period, the 5 surviving rats/group were given clinical pathology examinations, then sacrificed and necropsied. All rat were examined for gross and microscopic changes.

 

The analytically determined concentrations were 41, 650, and 1800 mg/m³ over the duration of the study. All rats survived to the termination of the study and were sacrificed by design. There were no test substance-related clinical signs of toxicity observed during the study. No statistically significant body weight differences were observed in any group. There were no compound-related adverse effects noted during clinical pathology or pathology evaluations. The no observed adverse effect level (NOAEL) was considered to be 1800 mg/m³.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEC

1 800 mg/m³

Study duration:

subacute

Species:

rat

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

This substance has been evaluated for repeated exposure toxicity in a 14-day and 90-day oral toxicity study in rats, and in a 10-day inhalation toxicity study in rats. The highest dose tested in the oral studies was 1000 mg/kg bw/day with no observed effects. This included a complete analysis of effects to sperm in the 90-day study. Therefore the NOEL for repeat-dose oral toxicity is 1000 mg/kg bw/day. The highest dose tested in the 10-day inhalation toxicity study was 1800 mg/m³, which also did not produce any effects. The inhalation NOEL is 1800 mg/m³. This substance has a low potential for repeated exposure toxicity, with no specific target tissues of toxicity identified.

Justification for classification or non-classification

Based on no effects at high exposure concentrations by the oral and inhalation routes of exposure, the substance does not need to be classified for repeated dose toxicity according to EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.