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Toxicological information

Toxicity to reproduction

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Administrative data

one-generation reproductive toxicity
based on test type (migrated information)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented study report equivalent or similar to OECD guideline 415: GLP

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
equivalent or similar to guideline
OECD Guideline 415 [One-Generation Reproduction Toxicity Study (before 9 October 2017)]
GLP compliance:
not specified
Limit test:

Test material

Constituent 1
Reference substance name:
C16-C30 highly refined light mineral oil
C16-C30 highly refined light mineral oil
Constituent 2
Reference substance name:
White mineral oil (petroleum)
EC Number:
EC Name:
White mineral oil (petroleum)
Cas Number:
Details on test material:
Test Material - Stock 461 white oil
Manufacturer - Witco Chemical Company
Density - 0.88 g/ml
White oil was made by severely hydrotreating a dewaxed feed stock

Test animals

Details on test animals or test system and environmental conditions:
- Source: Charles River Breeding Laboratories, Lakeview, NJ
- Diet: Purina Certified Rodent Chow #5002 (Checkers)
- Water (e.g. ad libitum):ad libitum
- Acclimation period: 3 weeks
- Age at study start - 7 week

Prior to parturition, cages housing presumed-pregnant animals were fitted with a stainless steel floor. Dams were provided with Beta Chip Bedding (Fisher and Sons, Bound Brook, NJ) as nesting material.

Administration / exposure

Route of administration:
Details on exposure:
Rats were clipped before the first day of study and weekly thereafter. Stock 461 was drawn up into a 1 cc syringe (calibrated in 0.01 cc) and during dispensing was spread evenly on the clipped dorsal skin of the rat using the tip of the syringe without the use of a needle. Application sites were not covered. Amount of test material applied to each animal was calculated using the most recently recorded body weight for each animal, the dose level and the density of the test material. Rats were fitted with cardboard Elizabethan-style collars to minimize ingestion of the test material. Collars were lined with soft rubbier tubing to minimize development of irritation or lesions.

During the mating period, the test material remained on the animals for a minimum of four hours. Excess material was removed with a gauze pad from the application site of each animal prior to cohabitation in an attempt to minimize test material ingestion during preening.

Untreated controls were not clipped nor collared and received no treatment. Dermal control female rats were clipped and collared as above. Dorsal skin of each rat was stroked with the tip of a 1 cc syringe but no test material was applied.

Details on mating procedure:
During the mating period, female rats which had not previously borne pups were placed with adult male rats from their corresponding treatment group in a ratio of 1:1 and observed daily for evidence of having engaged in breeding activity. Each morning during the period of cohabitation, the drop-pan papers under the animal cages were checked for the presence of expelled vaginal sperm plugs; additionally, each female rat was examined for the presence of in situ vaginal sperm plugs. Vaginal lavage fluid was obtained from each female which exhibited a vaginal sperm plug in situ or on the drop-pan papers, and was examined for the presence of spermatozoa. Females that were positive for sperm plug as well as for spermatozoa were considered to be at day 0 of presumed gestation and were placed in individual housing units. The cohabitation was continued until 20 presumed-pregnant female rats/group were obtained.
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
Premating period - 10 weeks
Mating period - 3 weeks
Postmating period - Gestation days 0-20
Frequency of treatment:
5 days/week
Details on study schedule:
Female rats were randomly divided into 5 groups (untreated control, dermal control, 125, 500 or 2000 mg/kg bw) using computer-generated random numbers. Each group consisted of 20 rats dosed dermally from premating to gestation day 20. 10 additional females were administered the test material during the premating period to assure the obtainment of twenty presumed-pregnant females.
Doses / concentrations
Doses / Concentrations:
0, 125, 500 or 2000 mg/kg body weight
other: Nominal dose calculated on the basis of animal body weight, dose level and density of test substance
No. of animals per sex per dose:
20 female rats/dose
Control animals:
yes, concurrent no treatment
yes, sham-exposed


Parental animals: Observations and examinations:
All rats were monitored throughout the study period until sacrifice for changes in appearance, behavior, excretory function, signs of ill-health and mortality. Additionally, each presumed-pregnant female was monitored during gestation for signs of abortion or premature delivery. During parturition, dams were observed for signs of dystocia (difficult delivery), and during lactation for maternal behavior (pup retrieval and nursing the litter); only observations that warranted comment were recorded.

Body weight of each rat was measured to the nearest 0.1 gram once weekly during the premating phase. No body weights were measured during the mating period. During the postmating phase, the body weight of each presumed-pregnant female was measured to the nearest 0.1 gram on days 0, 3, 6, 10, 13, 16, 18 and 20 of gestation and on days 0, 4, 7, 10, 14 and 21 of the postpartum period (lactation). The amount of food consumed for each animal was calculated for each week of the premating period and for gestation day intervals 0-3, 3-6, 6-10, 10-13, 13-16, 16-18 and 18-20. Food consumption was not measured during the mating and postpartum periods.
Oestrous cyclicity (parental animals):
The state of the estrous cycle of five female rats from groups I (untreated control), II (Dermal control) and V (2000 mg/kg bw/day) was determined daily (5 days/week) for two weeks prior to the mating period and continued until evidence of engaging in breeding activity was obtained. Each morning, vaginal lavage fluid was obtained from each female. A drop of the lavage fluid was examined under a microscope and the stage of estrus recorded.
Litter observations:
All offspring were observed throughout the postpartum period until sacrifice for changes in appearance, behavior, body weight, signs of nursing (milk in the stomach), ill-health or mortality. Additionally, as soon after birth as possible, all viable neonates were sexed and examined for external anomalies. Subsequently, each pup was monitored for opening of the eyes (eyelid disjunction) and the ability to right itself when placed on its back. Pups were weaned on postpartum day 21.
Postmortem examinations (parental animals):
Each female rat which delivered was sacrificed by over-exposure to carbon dioxide gas on postpartum day 21 or as soon as time permitted. Dams whose litters died during the postpartum period were sacrificed as soon as the operating schedule permitted. In all instances, the thoracic and abdominal cavities were exposed and all organs were examined grossly for evidence of parthosis. Reproductive organs (ovaries and uterus) were removed, examined grossly, weighed and fixed in 10% neutral buffered formalin. The number of uterine implantation sites in each urerine horn was counted and recorded. All other remarkable findings were recorded.
Postmortem examinations (offspring):
Surviving weanlings (from postpartum day 21) were sacrificed by over-exposure to ether or carbon dioxide gas on postpartum day 28 or as soon thereafter as time permitted. thoracic and abdominal cavities of each weanling were exposed and all the organs were examined grossly for evidence of pathosis.
Data generated during the gestation and postpartum phases wre analyzed by analysis of variance followed by group comparisons using the Fisher's exact or Dunnett's test. Differences were considered statistically significant if the probability of the difference being due to chance was less than 5% (p < 0.05).

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Dermal irritation, scabs and flaking of skin
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
not examined
Other effects:
not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed

Details on results (P0)

Dermal irritation was observed at the site of application which persisted after administration of test material. There was no treatment-related effect in maternal parameters such as food consumption, body weight gain. Reproductive parameters such as length of gestation, number of implants, litter size did not change compared to chamber controls.

Effect levels (P0)

Dose descriptor:
Effect level:
>= 2 000 mg/kg bw/day (actual dose received)
Basis for effect level:
other: There were no adverse effects to reproductive performance.

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
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)

Offspring body weights, viability, eyelid disjunction and surface righting ability were not affected adversely by in utero exposure to stock 461

Overall reproductive toxicity

Reproductive effects observed:
not specified

Applicant's summary and conclusion

NOAEL for fertility was greater than or equal to 2000 mg/kg body weight (highest dose tested)
Executive summary:

A one-generational reproductive toxicity study was conducted to evaluate the reproductive performance (gonadal function, all 4 stages of the estrus cycle, fertilization, implantation of the egg, gestation period and parturition) of a C16-C30 highly purified light mineral oil. The pre-natal developmental phase also evaluated pup growth and development up to weaning. Female Sprague-Dawley rats were dermally exposed to test material for 10 weeks premating period (5 days/week), a 3-week mating period (5 days/week) and up to gestation day 20. Test material was applied once daily to clipped, intact dorsal skin at a dose level of 125, 500, 2000 mg/kg bw/day. The application sites were not occluded and evaporation was not expected to affect dosing due to low vapor pressure. Treatment-related dermal irritation (erythema, formation of scabs, skin flaking) at site of exposure were observed in almost all exposed rats. Neonatal deaths observed 0-4 days postpartum was not considered treatment-related as this was also observed in the control groups. No clinical signs of systemic toxicity were observed and there were no effects on maternal body weight and food consumption. No differences were observed in mean numbers of implantation sites, live pups/litter, live birth index (total pups born alive/total pups born) either at birth, days 4 or 21 postpartum. There was no change in mean pup body weights and no pathological observations were seen in necropsied organs of the pups. NOAEL for mineral oil was ≥ 2000 mg/kg bw/day for fertility and pre-natal development.