Propane-1,3-diol

Repeated dose toxicity: oral

Administrative data

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

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1999

Reference 2

Reference Type:

publication

Title:

Subchronic toxicity study of 1,3-propanediol administered orally to rats

Author:

Gingell R, Kirkpatrick JB, and Steup DR

Year:

2000

Bibliographic source:

Int. J. Toxicology, 19:27-32

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Propane-1,3-diol

EC Number:

207-997-3

EC Name:

Propane-1,3-diol

Cas Number:

504-63-2

Molecular formula:

C3H8O2

IUPAC Name:

propane-1,3-diol

Details on test material:

- Purity: 100%

Test animals

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

Administration / exposure

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

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

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

Doses / concentrations 2

Dose / conc.:

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

Doses / concentrations 3

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.

Examinations

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.

Results and discussion

Results of examinations

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.

Effect levels

1

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

2

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

Target system / organ toxicity

Critical effects observed:

no

Any other information on results incl. tables

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

Applicant's summary and conclusion

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).