2,2,4-trimethylpentane-1,3-diol

Toxicity to reproduction

Administrative data

Endpoint:

three-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1974

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to acceptable scientific methodology in use at the time the study was conducted (prior to institution of GLPs).

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1974

Report date:

1974

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

After 30 days of ingesting diets containing 0.0 or 1.0% TMPD in a subchronic feeding study, 15 animals/sex/group were selected for a three-generation reproduction study and maintained on their respective diets. The first and second generations were bred for two groups of litters and the third was bred for three groups with the last group (F3c) delivered by Cesarean section.

GLP compliance:

no

Remarks:

study conducted prior to GLPs

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2,2,4-trimethylpentane-1,3-diol

EC Number:

205-619-1

EC Name:

2,2,4-trimethylpentane-1,3-diol

Cas Number:

144-19-4

Molecular formula:

C8H18O2

IUPAC Name:

2,2,4-trimethylpentane-1,3-diol

Details on test material:

-Test substance name (as cited in report): 2,2,4-trimethyl-1,3-pentanediol (TMPD)

Test animals

Species:

rat

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
-Animals: Albino rats
-Body weight: 190g (males) and 176g (females) at study start
-Diet: Purina Laboratory Chow supplemented with 5.0% Mazola corn oil ad libitum
-Drinking water: ad libitum

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on exposure:

Rats were fed TMPD at dose levels of 1.0 % TMPD in a basal diet of ground feed supplemented with 5% corn oil. The control group received the basal diet containing feed and corn oil only. Rats were exposed for the duration of the 3 generation study.

Details on mating procedure:

Mating consisted of pairing one male and one female per cage on Sunday evening through the following Friday morning. Daily vaginal smears were made. When a smear was positive, the male was removed from the cage and the day was designated as Gestation Day 0. All animals were maintained on their assigned diets throughout the entire study. The litters were not culled and the pups were weaned at 21 days of age.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

3 generations

Frequency of treatment:

continuously in the diet for 3 generations

Details on study schedule:

Groups of 15 rats/sex were fed diets containing either 0.0 or 1.0% test substance for 30 days as part of a subchronic repeated dose toxicity study, before being transferred to the reproductive phase of the study. These animals were designated as the parent generation (F0), and were mated twice for two groups of first generation litters (F1a and F1b). Approximately fifteen animals per sex, per group were randomly selected from the F1a litters and mated twice to produce two groups of second-generation litters (F2a and F2b). This process was repeated with the F2a animals to produce two groups of third generation litters (F3a and F3b). However, due to a questionable mortality rate seen in the F3a litters at one week postpartum, the F2a dams were allowed to mate and litter a third time to produce a third group of third generation litters (F3c). The F3c pups were not delivered, but were collected by laparotomy on Day 19 of gestation. All animals were maintained on their assigned diets throughout the entire study. The data recorded for each generation included: the number of inseminations and pregnancies, mean gestation period, and litter size and mortality at birth, weaning, and one and two weeks after weaning. Mean pup body weights were measured at weaning, one and two weeks post weaning, and at the time of necropsy. The pups in all litters from each generation, except for those that had been selected to be breeders, were euthanized and necropsied at 7 weeks of age. All breeders were euthanatized and necropsied shortly after they had produced the required groups of litters. All animals were examined for gross pathology, and selected tissues were collected from two male and two female rats from each litter for histopathology. Resorption sites were counted for the F2a dams, and the numbers of viable and dead fetuses were recorded for the F3c litters. The F3c fetuses were examined for gross abnormalities, weighed, and placed in either a 95% ethanol fixative or Bouin’s fixative.

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
1.0%
Basis:
nominal in diet

Doses / concentrations 2

Dose / conc.:

1 other: percent

No. of animals per sex per dose:

15 animals/sex/group

Control animals:

other: basal diet supplemented with corn oil

Examinations

Parental animals: Observations and examinations:

No data provided in study report

Oestrous cyclicity (parental animals):

No data provided in study report

Sperm parameters (parental animals):

No data provided in study report

Litter observations:

The data recorded for each generation (“a” and “b” litters) were: % inseminations, % pregnancies, mean gestation period length, number of litters, mean litter size, and % mortality at birth, weaning and 1-2 weeks after weaning.

-Body weights:
The average body weights of the pups were recorded at weaning, one and two weeks post weaning, and at the time of necropsy.

Postmortem examinations (parental animals):

-Scheduled necropsy:
All breeders, including the parent generation (F0), were necropsied after they had produced the required number of litters. All animals were necropsied and examined for gross pathology.

Postmortem examinations (offspring):

-Scheduled necropsy:
The pups in all litters of each generation, except those in the “a” litters which had been selected to be breeders, were necropsied at 7 weeks of age. Those animals selected as breeders but not used were necropsied at 14 weeks of age. Those pups selected as breeders were necropsied after they had produced the required groups of litters. In addition, the study was terminated by delivery of the F3c generation via laprohysterectomy on Gestation Day 19. Resorption sites and the number of viable fetuses and dead fetuses were recorded. The fetuses were examined for gross abnormalities and weighed. One-third of the fetuses were placed in 95% ethanol and the remaining two-thirds were fixed in Bouin's solution.

Pathology:
All pups in all litters from each generation were necropsied at seven weeks, fourteen weeks, or later (see schedule above). Tissues for pathology were only taken from 2 animals/sex/litter, where possible. The tissues collected and fixed in buffered 10% formalin were: trachea, lung, heart, tongue, esophagus, stomach, small intestine, large intestine, liver, kidney, urinary bladder, pituitary, adrenal glands, pancreas, thyroid gland, parathyroid glands, gonads, uterus, spleen, bone marrow, cerebrum, cerebellum, and eye.

Statistics:

Statistical detail was not mentioned although some data were noted as being significant based on the Student's “t” test and “two x two X^2" (Chi squared) test.

Reproductive indices:

Percent inseminations, per cent pregnancies, average gestation length, the number of litters and the average litter size or average number of implants were provided for each mating.

Offspring viability indices:

For each mating, the number of pups born, the % mortality at birth and one and two weeks post weaning, and average pup weights were determined,

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

not specified

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

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:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

not examined

Histopathological findings: non-neoplastic:

not examined

Other effects:

not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Details on results (P0)

-Mortality:
Test substance exposure did not cause any parental mortality.

-Reproductive performance:
There were no test substance-related effects on the % of inseminations, the % of pregnancies, the mean gestation length, the number of litters per group, or the average litter size.

-Body weights:
Dam body weights for the TMPD group were somewhat lower than controls during the first 30 days of the study (reported elsewhere).

Effect levels (P0)

1

Dose descriptor:

NOAEL

Remarks:

parental toxicity

Effect level:

1 other: %, nominal in diet

Sex:

male/female

Basis for effect level:

other: No parental mortality occurred. Body weight of F0 dams was somewhat lower than controls during the first 30 days of feeding.

Remarks on result:

other: Generation: all generations (migrated information)

2

Dose descriptor:

NOAEL

Remarks:

Reproductive/Developmental toxicity

Effect level:

1 other: %, nominal in diet

Sex:

male/female

Basis for effect level:

other: Percentages of inseminations, pregnancies, average gestation period, and litter size were comparable among treated and control groups. No biologically significant differences in pup growth or development were noted in any generation.

Remarks on result:

other: Generation: all generations (migrated information)

Results: F1 generation

General toxicity (F1)

Clinical signs:

not specified

Mortality / viability:

mortality observed, treatment-related

Body weight and weight changes:

effects observed, treatment-related

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

-Mortality:
Mortality of the young at birth was higher in the control group except for generation F3a. The greatest numbers of deaths (9 of 13) in the treated group at this time were all from one litter. Where high mortality occurred from birth to weaning, the majority of deaths occurred in one to two litters and may be an indication of the dam’s inability to nurse rather than a test substance-related effect. The high percentages of mortality during this time period were seen in both the control and treated groups. In the F3a generation, the treated group had 30 deaths involving 7 of 15 litters, while the control showed only 5 deaths in 3 of 13 litters from weaning to one week after weaning. This increase in mortality prompted an additional (F3c) mating in the F3 generation and there was no increase in mortality in the F3b generation. Mortality from 1 week to 2 weeks after weaning was negligible in all except the F1a group but the majority of deaths were due to the demise of a complete litter.

-Body weights:
Mean body weights of the pups born to TMPD treated dams were somewhat lower than controls at all time intervals in all generations. The only consistent statistically significant lower body weights were measured in the F2b generation. This difference was not seen in the groups of litters in the preceding or succeeding generations. A lower body weight for dams delivering the F1a and F1b generations was suggested based on results for the first 30 days of feeding; however, data supporting this effect during the rest of the study was not presented in the report.

-Pathology:
No effects on gross pathology were noted in any generation and in pups allowed to survive to 7-9 weeks of age. Based on these results, the tissues collected were not examined nor were the F3c fetuses processed.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

There were no test material-related effects on mating performance, fertility, mean gestation length, numbers of litters, or mean litter size in a reproduction and developmental toxicity study in which male and female rats were exposed ad libitum in the diet to 0 or 1% 2,2,4-trimethyl-1,3-pentanediol for three generations. There were no significant effects on mean number of pups born, the percent mortality at birth, post natal survival, or pup weights. The NOAEL for reproductive and neonatal toxicity was 1%, the only dose level tested.

Based on the absence of significant reproductive and developmental effects in this study, this substance is not classified for Reproductive or Developmental Toxicity according to the UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS) or EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) 1272/2008. 2,2,4-Trimethyl-1,3-pentanediol is not currently classified for Reproductive or Developmental Toxicity according to Directive 67/548/EEC. The substance is also not classified for effects on or via lactation.

Executive summary:

Groups of 15 rats/sex/group were fed diets containing either 0.0 or 1.0% 2,2,4-trimethyl-1,3-pentanediol (TMPD) for 30 days as part of a subchronic repeated dose toxicity study before being transferred to the reproductive phase of the study. These animals were designated as the parent generation (F0), and were mated twice for two groups of first generation litters (F1a and F1b). Fifteen animals per sex, per group were selected from the F1a litters and mated twice to produce two groups of second-generation litters (F2a and F2b). This process was repeated with the F2a animals to produce three groups of third generation litters (F3a, F3b, and F3c). Pup mortality rates from birth to two weeks post weaning were erratic across generations. Treated litters from three generations (F1b, F2a, F3a) had significantly higher mortality rates than the control group; treated litters from two generations (F1a, F3b) had mortality rates that were comparable to the control group, while treated litters from one generation (F2b) had a significantly lower mortality rate than the control group. In the majority of these cases, differences in mortality were the result of the loss of one or two litters. The only consistent statistically significant effects on pup body weights were seen in the F2b generation but this difference was not seen in the groups of litters in the preceding or succeeding generations. In addition, no gross lesions or developmental effects were observed at necropsy in this or any other group or generation. Under the conditions of this three generation study, the no-observed adverse effect level (NOAEL) for reproductive and developmental toxicity was considered to be 1.0% in male and female rats exposed to 2,2,4-trimethyl-1,3-pentanediol (TMPD).