2,2',6,6'-tetra-tert-butyl-4,4'-methylenediphenol

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

The substance  when given at dietary levels up to 1.25%  to females 7 days prior to mating and through mating and gestation, did not affect gestation length, size of pups, total number of young per litter, or stillbirths per litter compared to control animals.  

Link to relevant study records

Reference

Endpoint:

three-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Version / remarks:

1983

GLP compliance:

no

Remarks:

Prior to GLP requirements

Species:

rat

Strain:

Crj: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Brookline, Massachusetts
- Age at study initiation: (P) weanling rats, 2 weeks acclimation, 8 weeks on test diets before initial pairings at about 105 days of age; offspring that would be parents in next generations weaned at 21 days and fed on same diets as progenitors
- Fasting period before study: none
- Housing: 4 females or 3 males per cage if not in mating portion of study; 2 females and 1 male during mating segment; 1 pregnant female in individual nesting box during gestation;

- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): as libitum
- Acclimation period: initial animals observed 2 weeks prior to assigning to test groups

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 76.2 +/- 2 degrees F
- Humidity (%): 40 to 60 per cent desired
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light):

IN-LIFE DATES: From: To:

Route of administration:

oral: feed

Vehicle:

other: Corn oil used to carry test article into feed

Details on exposure:

DIET PREPARATION
- Rate of preparation of diet (frequency): weekly
- Mixing appropriate amounts with (Type of food): Special preparation of Rockland Mouse and Rat diet containing no more than 1.0% of fat and free of any antioxidant commonly added as stabilizer and preservative to edible fats was the base diet. For the control diet, 1 kg corn oil added to 19 kg of base diet, and the mixture stirred for 20 minutes. This yielded 20 kg of diet (control) containing not more than 6.0% fat, and no antioxidants other than what occured naturally. For test diets, appropriate amount of test article added to corn oil to make 1 kg and this mixture added to 19 kg of base diet.
- Storage temperature of food: base diet received fresh every 2 months and stored under refrigeration until stored

VEHICLE
- Justification for use and choice of vehicle (if other than water): Corn oil used as carrier to introduce test article into diet, and to supply an adequate nutritional fat for a rat diet, as the base food was restricted to no more than 1.0% fat to avoid fat stabilizing antioxidants
- Concentration in vehicle: 300, 1200, 2000, 10,000 or 60,000 mg test article added to corn oil up to 1 kg.

Details on mating procedure:

- M/F ratio per cage: 1 male, 2 females
- Length of cohabitation: until females showed notable weight gain, or 4 weeks
- After 4 weeks of unsuccessful pairing replacement of first male by another male with proven fertility. Unsuccessful males placed with females of established fertility.
- After successful mating each pregnant female was caged (how): Individual nest boxes

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Initial progenitors: 8 weeks prior to first mating, then throughout gestation, and second mating period and gestation
F1, F2, or F3: from weaning if selected to reproduce, then through mating and two gestations

Frequency of treatment:

Initial group: fed control or treated diets for 8 weeks prior to breeding. Thereafter, animals were on appropriate feed for their group from weaning.

Details on study schedule:

- Age at mating of the mated animals in the study:
Initial animals: 105 days of age, 8 weeks on test diets initially. If mated, allowed to deliver, pups nurse for 7 days, then after 1 week allowed a second mating. If neither female in cage obviously pregnant, a second male placed with females after 4 weeks; second mating as described before.
F1 and F2: initially mated at about 3 months of age, had been on test diets with dams while nursing, and then from weaning on. Second mating after pups allowed to nurse for 7 days, and then allowed to mate after 1 week.

Selection of parents from F1 and F2: Pups of 2nd mating were allowed to nurse for 3 weeks (weaning). At that point, the offspring were grouped by sex, and counted within each dosing group. Animals were reduced in number by random selection to 20 females and 10 males to continue as progenitors of the next generation.

Remarks:

Doses / Concentrations:
15 ppm
Basis:
nominal in diet

Remarks:

Doses / Concentrations:
60 ppm
Basis:
nominal in diet

Remarks:

Doses / Concentrations:
100 ppm
Basis:
nominal in diet

Remarks:

Doses / Concentrations:
500 ppm
Basis:
nominal in diet

Remarks:

Doses / Concentrations:
3000 ppm
Basis:
nominal in diet

No. of animals per sex per dose:

20 females, 10 males per dose group for each breeding generation

Control animals:

yes, plain diet

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: No data

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: Initial parents: At study initiation
Pups: at birth, 4th day for first breeding offspring of each group, at 7th day and weaning for second breeding group of each dose

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes / No / No data
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes / No / No data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes / No / No data
- Time schedule for examinations:

OTHER:

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 7 postpartum: in the second breeding offspring for each dose group
- If yes: 20 females and 10 males randomly selected; excess pups were killed and discarded.

PARAMETERS EXAMINED
The following parameters were examined in [F1 / F2 / F3] offspring: Those that died or were killed and examined at 4, 7, or 21 days of age
[number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural abnormalities, ]

GROSS EXAMINATION OF DEAD PUPS:
yes, for external and internal abnormalities; possible cause of death was determined for pups born or found dead.

HISTOLOGICAL EXAMINATION OF PUPS:
The pups of the thrid generation (F3a and F3b) had histological examination of the brain, heart, lungs, kidneys, liver, spleen, intestinal tract, and adrenal glands

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals as soon as possible after the last litters in each generation were produced
- Maternal animals: All surviving animals after the last litter of each generation was weaned

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations including the cervical, thoracic, and abdominal viscera of all animals dying during the test.

Postmortem examinations (offspring):

SACRIFICE
-The first litter of each initial female was sacrificed after suckling for 7 days. The offspring of the second litter were allowed to nurse 3 weeks, and those not selected for parenting were sacrificed. Pups in the first litters of the F1 and F2 females were counted and weighted at 4 days of age; those of the F1 females were then killed and dams remated. Pups in both litters of the F2 females and those in the second litter of the F1 females wee reduced to 10 pups, and allowed to suclke at 21 days of age. Representatives of the F3 generations were killed at 21 days of age.
- The F3 offspring were subjected to postmortem examinations (macroscopic and/or microscopic examination) as follows:

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations including the cervical, thoracic, and abdominal viscera.

HISTOPATHOLOGY / ORGAN WEIGTHS
The tissues indicated below were weighed and prepared for microscopic examination. Tissues were fixed in neutral formalin, embedded in paraffin, and sectioned. Sections were stained with hematoxylin and eosin.
Brain, heart, lungs, liver, kidneys, spleen, intestinal tract and adrenal glands

Reproductive indices:

Fertility index: Number of pregnancies/number of matings x 100
Gestation Index: Number of litters with live pups/Number of pregnancies x 100
Live Birth Index: Number alive at birth/ total number delivered x 100 (Based on first observation of the litters)

Offspring viability indices:

Viability Index: Number of Rats alive on 4th Day/ Total number Delivered x 100 (Day 7 for F1 generations)
Lactation index: Number of pups alive on 21st day/ Number continued after Day 4 x 100
Overall mortality among progeny throuhout 21 days of nursing (in %)

Clinical signs:

no effects observed

Description (incidence and severity):

associated with test article administration

Reproductive function: oestrous cycle:

no effects observed

Description (incidence and severity):

Associated with test article administration

Reproductive performance:

no effects observed

Description (incidence and severity):

associated with test article administration

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS): Occasional fatalities among procreating animals were attributable to pneumonia and in some instances to dystocia. Throughout 3 genearations of procreators there werre 13 deaths among 180 males and 360 female progenitors. Three of the 10 females died of dystocia. The presence of disease among the animals, including control animals, was indicated by occasional anorexia, loss of body weight and rales in the lungs. It was thought that a dry atmosphere in the initial animal rooms contributed to the illness.


REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS): Test article administration to procreating animals had no effect on fertility or on the extent to which they produced live offspring. Exceptional variation in fertility index and in gestation index were attributed to influence of extraneous disease and not related to test article. Fertility of the initial progenitors (including controls) was poor. Subsequent generations had satisfactory performance. The number of pregnanccies resulting from the matings showed no relationship to test article in diet. During the two periods of mating of the initial progenitors, more pregnancies occurred in treated females (3000 ppm in diet) than in controls. The least number of pregnancies in th e(P) rats was in the animals with 60 ppm in the diet. Among the first generation of offspring (F1) the fertility index was lowest in the group fed 3000 ppm, and highest (100%) in the animals fed 500 ppm in the diet. Among the second generation (F2) of progeny, fertility was slightly low in both periods of mating in animals at 15 ppm in the diet. It was also slightly low in the first period, but not the second period, of mating of the rats fed 100 ppm. As there was no consistent pattern of effect, the differences in fertility were not thought to be attributalbe to test article administration.
Of the 180 male progenitors in the whole test, only 7 failed to sire litters; five of those were inital progenitors (3 at 60 ppm, 2 at 500 ppm). One male of the F1 generation on the 3000 ppm diet and one male of the F2 generation on the 15 ppm level also failed to sire offspring. These failures were attributed to sporadic disease unrelated to the test article.
The gestation index was lowest during the second period of mating of the original progenitors in the control group. It was consistently high among females of the 500 and 3000 ppm diet groups. Of the 60 females of the 3 generations on test, there were no differences attributable to test article in the numbers that produced 0, 1, or 2 litters when the means were compared by chi-square.

Dose descriptor:

NOEC

Effect level:

3 000 ppm (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Remarks on result:

other: Generation: Parental, F1, F2, F3 (migrated information)

Clinical signs:

no effects observed

Description (incidence and severity):

associated with test article

Dermal irritation (if dermal study):

not examined

Mortality / viability:

no mortality observed

Description (incidence and severity):

associated with test article

Body weight and weight changes:

no effects observed

Description (incidence and severity):

No remarkable effect on weights at birth, day 4 (7) or when weaned at 21 days

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not examined

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Sexual maturation:

not specified

Anogenital distance (AGD):

not specified

Nipple retention in male pups:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Description (incidence and severity):

No anatomic anomaly, structural abnormality in the 5400 progeny examined. No gross pathology found in F2 and F3 offspring

Histopathological findings:

no effects observed

Description (incidence and severity):

No histopathology in tieeuse of third generation offspring examined

Other effects:

not specified

Behaviour (functional findings):

not specified

Developmental immunotoxicity:

not specified

VIABILITY (OFFSPRING): Probability of survival at birth, and during first days of life was generally poor among th efirst generatin progeny ranging from 45.9 to 73% without regard to test article in the diets of the parents. The viability index improved in the second generation ranging from 89.4 to 97.4%, and was normal in the third generation except for the offspring of parental group receiving 60 ppm test article in diet; viability in that group was 84.9%, The poor life expectancy of the progeny was attributed in every instance to the influence of extraneous disease, and not the test article.
Survivability during nursing period (lactation index) ranged from 47.3 to 91.9% in the second generation and from 66.5 to 94.6% in the third generation; differences were not attributable to test article administered to the lactating females.

CLINICAL SIGNS (OFFSPRING): No remarkable differences in clinical signs were seen in the offspring of treated procreators compared with control pups

BODY WEIGHT (OFFSPRING): Content of test article in the procreating animals had no remarkable effect on body weights of the offspring at birth, at 4 days of age, or when weaned at 21 days.


GROSS PATHOLOGY (OFFSPRING): No gross pathological changes were found in the F2 and F3 offspring.

HISTOPATHOLOGY (OFFSPRING): Histopathological exam of the brain, heart, lungs, kidneys, liver, spleen, intestinal tract and adrenal glands of the third generation of offspring (F3) revealed no pathological alterations.

Dose descriptor:

NOEC

Generation:

F1

Effect level:

3 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Remarks on result:

other: clinical signs; mortality; body weight; gross pathology; organ weights; histopathology; mating index; fertility index; birth index; live birth index; pregnancy index; litter size; litter weight; pup weight; survival index; viability index; lactation ind

Reproductive effects observed:

not specified

Lowest effective dose / conc.:

3 000 ppm

Treatment related:

not specified

The Gestation Index of Successive Generations of Rats on Diets with and without Test Article (Table 1 )

Test article concentration in diet (ppm)	1^stMating Period (%)	2^ndMating Period (%)	Average for Both Matings (%)
Initial Parents (P)
0	100.0	75.0	87.9
15	91.7	89.5	90.3
60	100.0	100.0	100.0
100	100.0	83.3	90.9
500	100.0	93.8	96.8
3000	100.0	93.8	97.0
Generation F1
0	100.0	100.0	100.0
15	100.0	94.7	97.4
60	94.7	100.0	97.4
100	100.0	94.1	97.2
500	100.0	100.0	100.0
3000	100.0	100.0	100.0
Generation F2
0	100.0	100.0	100.0
15	100.0	100.0	100.0
60	100.0	90.0	94.7
100	100.0	100.0	100.0
500	100.0	94.7	97.4
3000	100.0	94.4	97.3

Gestation Index:   Number of litters with live pups/Number of pregnancies x 100

Groupings of Females Fed Each Diet and the Number of Litters They Produced (Table2)

Test Article Concentration in the Diet (ppm)	Number of females which produced the indicated number of litters
Number of Litters	0	1	2
0	2	8	50
15	5	11	44
60	6	14	40
100	3	14	43
500	2	10	48
3000	4	11	45
No Test Article	2	8	50
Test Article Diets	20	60	220

Diets with and without Test Article (Viability Index) (Table 3)

Test article concentration in diet (ppm)	1^stMating Period (%)	2^ndMating Period (%)	Average for Both Matings (%)
Generation F1
0	81.3	61.6	73.1
15	83.7	36.5	55.7
60	81.9	64.9	73.1
100	68.3	20.8	45.9
500	83.3	29.4	56.0
3000	74.7	31.5	56.2
Generation F2
0	96.3	98.5	97.4
15	96.3	90.4	93.3
60	92.3	95.7	94.1
100	99.4	80.3	89.4
500	98.6	88.8	93.4
3000	98.9	92.8	96.2
Generation F3
0	96.4	91.5	93.8
15	97.0	96.4	96.7
60	88.4	81.5	84.9
100	96.5	98.0	97.3
500	98.9	92.6	95.6
3000	98.8	94.9	96.6

* Seventh Day for Generation F1  

Viability Index: Number of Rats alive on 4^thDay/ Total number Delivered x 100

Percentage Number of Animals Alive at Birth (Live birth Index) (Table 4)

Test article concentration in diet (ppm)	1^stMating Period (%)	2^ndMating Period (%)	Average for Both Matings (%)
Generation F1
0	93.6	81.2	87.4
15	96.3	80.7	88.5
60	98.1	98.2	98.2
100	94.6	84.6	89.6
500	98.5	91.2	94.8
3000	98.8	92.3	95.6
Generation F2
0	97.9	100.0	99.0
15	97.2	96.1	96.6
60	94.2	97.0	95.6
100	100.0	98.9	99.4
500	99.0	98.3	98.6
3000	100.0	100.0	100.0
Generation F3
0	99.5	98.6	99.0
15	99.5	100.0	99.8
60	97.0	97.6	97.3
100	100.0	100.0	100.0
500	99.5	99.0	99.2
3000	100.0	97.2	98.6

Live Birth Index: Number alive at birth/ total number delivered x 100

(Based on first observation of the litters)

Conclusions:

The test substance was administered in diet at 0, 15, 60, 100, 500, and 3000 ppm (nominal) to 3 successive generations of breeding rats. Over the course of the study, animals were affected by environmental conditions and extraneous disease that were unrelated to test article in the diet. However, it can be concluded from this study that the substance in the diet up to levels of 3000 ppm did not affect fertilityof rats, viability of offspring, or caused abnormalities in the offspring under the conditions of this 3-generation study

Executive summary:

Diets containing the test substance in the nominal amounts of 0, 15, 60, 100, 500, and 3000 ppm were fed to 3 successive generations of breeding rats. Over the course of the study, animals were affected by environmental conditions and extraneous disease that were unrelated to test article in the diet. However, the data warrant the following conclusions:

1. Occasional fatalities among the breeding animals were attributable to respiratory disease, and in some cases dystocia.

2. The content of test article in the diet had no effect on fertility of the breeding animals, or on the extent to which they produced living offspring. Exceptional variations in fertility index and in gestation index were attributed to the influence of extraneous disease unrelated to test article concentration in diet.

3. The probability of survival at birth and during the first days of life, the viability index, was generally poor among the first generation ranging from 45.9 to 73 per cent without regard to test article concentration in the diet fed to the parents. The viability index improved in the second generation ranging from 89.4 to 97.4% and was normal in the third generation except for the group fed a test article diet containing 60 ppm. At that concentration level, viability was 84.9%. The poor life expectancy of offspring in the various groups was attributed to extraneous factors and not test article concentration in the diet.

4. The survival during the time the pups were nursed (the lactation index) ranged from 47.3% to 91.9% in the second generation, and from 66.5 to 94.6% in the third generation. The variation was not attributed to test article concentration in the diet.

5. The content of test article in the diets of the breeding animals exerted no remarkable effect upon the body weights of the offspring at birth, at 4 days of age, or when weaned at 21 days of age.

6. No anatomical anomaly or structural abnormality was found among 5400 rats that were offspring of animals on diets containing test article.

7. No gross pathological changes were found in the F2 and F3 offspring. Histological examination of the brain, heart, lungs, kidneys, liver, spleen, intestinal tract, and adrenal glands of the third generation of offspring revealed no pathologic alterations. 

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Study duration:

chronic

Species:

rat

Quality of whole database:

Although the study is from 1969 and some deficiencies including infections in the animals are noted, no indications of a test substance related impairment of fertility have been observed up to the highes dose tested: 3000 ppm (nominal) in the diet. The findings are corroborated by the repeated dose studies in rats and dogs with a duration of 90 days and two years in which no significant changes in the reproductive organs were observed.

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

A reproduction-developmental screening test according to OECD 421 did not reveal any effects on fertility or embryonic development at the highest recommended dose of 1000 mg/kg bw. The NOAEL for both parental and reproductive toxicity was 1000 mg/kg bw, the highest dose tested.

 

A 3 generation study in rats receiving the substance in the diet at nominal concentrations up to 3000 mg/kg diet (ppm) did not reveal any test substance related effect on fertility. The finding is corroborated by the absence of significant effects on the reproductive organs in repeated dose toxicity studies of 3 months and 2 years duration in rats and dogs at comparable dose levels. Consequently based on the available data, the substance is not classified for reproductive toxicity / fertiltiy according regulation EC 1272/2008 and amendments.

Short description of key information:
A 3 generation study in rats receiving the substance in the diet at nominal concentrations up to 3000 mg/kg diet (ppm) did not reveal any test substance related effect on fertility. The finding is corroborated by the absence of signficant effects on the reproductive organs in repeated dose toxicity studies of 3 months and 2 years duration in rats and dogs at comparable dose levels.

Justification for selection of Effect on fertility via oral route:
A 3-generation reproduction toxicity study in rats receiving the substance in their diet is available and the key study for this endpoint.

Effects on developmental toxicity

Description of key information

Two developmental toxicity studies, one in rats and one in rabbits are available. Groups of pregnant rats or rabbits received either 15 or 150 mg/kg bw  per day by gavage from day 6 to 15  and day of gestation respectively. Concurrent vehicle control animals were included. No test substance related effects on maternal toxicity and embyo fetal development were observed up to the highest dose tested. From the repeated dose studies it can be concluded that the administrerd dose was close to the maximum tolerated dose. The absence of developmental toxicity is also corroborated by the 3-generation study in rats. The studies in combination give sufficient confidence to conclude  that the substance is unlikely to cause adverse effects to the developing embryo or fetus.

Link to relevant study records

Reference

Reference 1

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study followed acceptable scientific practice for the time period.

Principles of method if other than guideline:

Artificially inseminated rabbits received test article in gelatin capsules, or empty capsules if in control group. Animals observed daily, and were Caesarian section performed on Day 28, 29 or 30 of pregnancy. Uterine and ovarian observations were made of implantation sites, corpora lutea, and fetuses (live and dead) counted, measured and weighed. Fetuses were examined for soft tissue development, and stained and examined for skeletal development.

GLP compliance:

no

Limit test:

no

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Rowmar rabbitry
- Age at study initiation: Adults of proven fertility
- Diet (e.g. ad libitum): Purina Chow ad libitum
- Water (e.g. ad libitum): Ad libitum

IN-LIFE DATES: From: Insemination April 7, 1970. To: Caesarean section May 7, 1970

Route of administration:

oral: capsule

Details on exposure:

VEHICLE
- Justification for use and choice of vehicle (if other than water): No vehicle, powder in gelatin capsules

Analytical verification of doses or concentrations:

no

Details on mating procedure:

- Impregnation procedure: artificial insemination after stimulation of ovulation by administration of Pituitary Luteinizing Hormone
- Verification of same strain and source of both sexes: yes

Duration of treatment / exposure:

Dose administered once daily from day 6 to day 18 of pregnancy

Frequency of treatment:

Once daily

Duration of test:

Caesarian section on day 28, 29 or 30 of gestation

Remarks:

Doses / Concentrations:
15 mg/kg body weight
Basis:
actual ingested

Remarks:

Doses / Concentrations:
150 mg/kg body weight
Basis:
actual ingested

No. of animals per sex per dose:

15 females bred per group

Control animals:

yes, sham-exposed

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations: mortality, appearance, behavior

BODY WEIGHT: Yes
- Time schedule for examinations: study intiation, weekly, and termination

FOOD CONSUMPTION Yes, recorded daily

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day #28, 29, or 30
- Organs examined: Uterus, ovaries in particular

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: Yes, right, left
- Number of implantations: Yes right horn, left horn
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Other: number pups, and location in horns

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: all per litter
- Skeletal examinations: Yes: all per litter
- Head examinations: Yes: all per litter

Indices:

Ratio of implantation sites/ corpora lutea

Details on maternal toxic effects:

Maternal toxic effects:no effects. Remark: that could be attributable to test article

Details on maternal toxic effects:
Maternal data: One death occurred in a control female, and one in low dose treated females. Both animals that died were found on Day 6 following dosing; pregnancy could not be determined. In those animals which survived until study termination, three control females had aborted.
One low dose animal was not pregnant, although one corpus luteum was found. Six high level females were not pregnant. Two of the high dose non-pregnant animals had three corpora lutea each. Animals that were pregnant and did not abort were comparable in body weights and food consumption.
Uterine/Caesarian data: Ratio data included those pregnant animals in which CL in both ovaries were determined. The ratio between implantation sites and number of corpora lutea observed was comparable between control and treatment groups.
There were no meaningful differences between control and test groups in the number, and placement of implantation and resorption sites, in the number, weight, and length of live and dead fetuses, or in incubation survival. The number of dead fetuses was slightly elevated in the control and high levels. In the control group, 10 litters were evaluated, and three litters had resorption sites, and 2 had dead fetuses. In the 15 mg/kg/day group, 13 litters were evaluated; 5 had resorption sites and 5 litters had dead fetuses. In the 150 mg/kg/day group, 9 litters were evaluated; 4 litters had resorption sites and 5 had dead fetuses.

Dose descriptor:

NOAEL

Effect level:

>= 150 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects. Remark: that could be attributed to test article

Details on embryotoxic / teratogenic effects:
External and Visceral Data for Fetuses: Three low level and 5 high level fetuses found dead at Caeserian section were too small to weigh or measure. Bruising was noted in four dead control pups and one live pup from one litter that were delivered normally. Ten of the dead aborted control fetuses were macerated or mutilated. One live low level fetus had all the first digits of the forepaw missing.
Skeletal data: Evaluations of the skull, ribs, sternum, vertebrae, pelvic girdle, long bones, fore and hind paws of the animals were made. The fetuses from the three aborted control litters, three dead low level fetuses, and six dead high dose level fetuses were either too small or damaged to be processed for skeletal evaluation. The fetuses delivered by Caesarian section and those delivered naturally wee stained and cleared. Single ribs, ribs described as small, and ribs described as “floating” in appearance or unattached from the vertebral column were located at the 20th vertebrae in all animals in which they were observed. Rudimentary bone structures noted on the left side of the vertebral column were observed at the 20th vertebra in two control and one high level fetus. One low level fetus had one nonossified portion of the left parietal bone and two in the right. Several (numbers 1-4) sternabrae were irregular in shape in one high level fetus; an extra ossification center was located on the first sternebra in one control fetus. All of the first digits in both forepaws were missing with no signs of any structure in one low level fetus.
There were no meaningful differences in the developmental indices of the test groups as compared to control. No trends towards lesser or greater skeletal development were observed.

Dose descriptor:

NOAEL

Effect level:

>= 150 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Abnormalities:

not specified

Developmental effects observed:

not specified

Uterine and Litter Data

Group (No. Pregnant/died/ aborted)	Implant sites (mean)	Resorption sites (mean)	Live Fetuses (mean)	Dead Fetuses (mean)	Weight/ Length Live Fetuses (mean) grams/cm	Weight/ Length Dead fetuses (mean) grams/cm	Incubation Survival (Percent)
Control (14/1/3)	9.1	0.3	7.6	1.2	36.8 /8.5	18.5/6.3	87.5
15 mg/kg (13/1/0)	9.3	0.7	8.2	0.4	38.6/8.8	19.3/6.8	77.6
150 mg/kg (9/0/0)	10.8	0.7	8.8	1.3	38.2/8.8	15.0/5.3	81.8

Skeletal Examination Data

Skeletal Effect	Control	15 mg/kg group	150 mg/kg group
Skull
Closure Grade 0	0	0	0
1	0	0	0
2	0	0	3
3	2	4	3
4	94	105	79
Nonossified Parts, Parietal Bone	0	1	0
Ribs
Pairs 12	79	91	67
Pairs 13	15	18	18
Pairs 14	1	0	0
Single	10	11	10
Small	16	24	22
Floating	6	7	8
Rudimentary	2	0	1
Vertebrae - caudal
Nonossified Centra
2	0	1	0
13	0	0	1
Nonossified Dorsal Arches
2	0	1	0
13	0	0	1
Sternum Ossification Centers
Absent          1^st	0	0	1
2^nd	0	0	2
3^rd	0	0	1
4^th	0	0	3
5^th	49	46	36
6^th	8	3	10
Small            1^st	2	1	3
2^nd	4	3	5
3^rd	1	1	1
4^th	3	3	1
5^th	44	52	35
6^th	19	34	20
Split              1^st	0	0	0
2^nd	1	0	0
3^rd	1	0	0
4^th	1	0	0
5^th	5	3	3
6^th	5	2	0
Irregular	0	0	1
Extra center	1	0	0
Pelvis Ossification Centers Absent
Right Pubis	0	3	5
Left Pubis	0	3	5
Forepaws Ossification Centers
Total Number Absent
Carpus             4	96	109	85
Metacarpus   1-2	19	14	17
3-4	0	1	2
5-10	0	0	2
Phalanges   1-15	40	23	25
16-20	0	1	3
21-28	0	0	1
Hindpaws Ossification Centers
Total Number Absent
Tarsus                2	1	4	2
4	0	0	5
Metatarsus       1-2	0	0	1
3-4	0	0	0
5-10	0	0	2
Phalanges        0-15	12	11	13
16-20	0	0	2
21-24	0	0	1

Conclusions:

In a rabbit teratology study, where female rabbits were dosed by capsule on days 6 through day 18 of pregnancy, there were no effects that could be related to test article as to maternal mortality.  Appearance, behavior, body weight gain, and food consumption were comparable among control and test animals. All uterine, litter, and Caesarian data were also comparable. There was no indication of a treatment related effect in fetal external appearance, visceral anatomy, development and skeletal structure of the test offspring compared to control.

Executive summary:

Forty-five female albino rabbits were bred by artificial insemination after stimulation of ovulation by administration of Pituitary Luteinizing Hormone. Fifteen animals were assigned to each test or control group. Test article was administered orally by capsule to female rabbits from day 6 to day 18 of pregnancy. Test article doses were either 15 or 150 mg/kg body weight, and control animals received empty gelatin capsules. Pregnancy was observed in 36 of the 45 animals bred (14 control, 13 low dose group, 9 high dose group). One control and one low dose female died during the study before pregnancy could be determined. Abortion was noted in 3 control animals. One control animal delivered naturally; all other control and test litters were delivered by Caesarian section.  Appearance, behavior, body weight gain, and food consumption were comparable among control and test animals. All uterine, litter, and Caesarian data were also comparable. There was no indication of a treatment related effect in fetal external appearance, visceral anatomy, development and skeletal structure of the test offspring compared to control.

Reference 2

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1970

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study followed acceptable scientific practice for the time period.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

Admin. From day 6 to 16 of gest., 2 dose groups only

GLP compliance:

no

Remarks:

prior to GLP

Limit test:

yes

Species:

rat

Strain:

Crj: CD(SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories Inc.
- Age at study initiation: Adult no further data
- Weight at study initiation: no data
- Fasting period before study: no
- Housing: inidividual after succesful mating
- Diet ad libitum
- Water ad libitum

Route of administration:

oral: gavage

Vehicle:

corn oil

Remarks:

1.5 and 15 mg/l suspension

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Justification for use and choice of vehicle (if other than water): corn oil was used to achieve some solubility and a fine dispersion of the TS
- Concentration in vehicle: 1.5 and 15 mg/l
- Amount of vehicle (if gavage): 1 ml/100 g of bw

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

- cohoused:
- M/F ratio per cage: 1/2
- Length of cohabitation: no data
- Verification of same strain and source of both sexes: yes
- Proof of pregnancy: sperm in vaginal smear eferred to as day 0 of pregnancy

Duration of treatment / exposure:

Daily from day 6 to day 15 of gestation

Frequency of treatment:

Daily

Duration of test:

Day 19 of gestation

Remarks:

Doses / Concentrations:
15, 150 mg/kg bw
Basis:
actual ingested

No. of animals per sex per dose:

Vehicl control : 18 females
15 mg/kg bw dose group: 18 females
150 mg/kg bw dose grou: 19 females

Control animals:

yes, concurrent vehicle

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations checked: Mortality, appearance, behavoir

BODY WEIGHT: Yes
- Time schedule for examinations: At day 0, 5, 10, 15, 19.

FOOD CONSUMPTION : Yes
- rcorded prior to treatment, at two intervals during treatment and after treatment until sacrifice
POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 19
- Organs examined: gross examination of uterine and visceral structures

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included
- Gravid uterus weight: No data
- Number of corpora lutea: No data
- Number of implantations: Yes
- Number of resorptions: Yes

Fetal examinations:

- External examinations: Yes:
- Soft tissue examinations: Yes: one third of each litter
- Skeletal examinations: Yes: 2/3 of each litter
- Head examinations: Yes: in the animals used for visceral examination (1/3)

Statistics:

not reported

Clinical signs:

no effects observed

Description (incidence and severity):

associated with test article administration

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, non-treatment-related

Description (incidence):

Occasional fatalities among procreating animals were attributable to pneumonia and in some instances to dystocia. Throughout 3 generations of procreators there were 13 deaths among 180 males and 360 female progenitors. Three of the 10 females died of dystocia. It was thought that a dry atmosphere in the initial animal rooms contributed to the illness.

Body weight and weight changes:

not specified

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not specified

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Immunological findings:

not specified

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

not specified

Neuropathological findings:

not specified

Histopathological findings: non-neoplastic:

not specified

Histopathological findings: neoplastic:

not specified

Number of abortions:

not specified

Pre- and post-implantation loss:

not specified

Total litter losses by resorption:

effects observed, non-treatment-related

Description (incidence and severity):

One dead fetus was found in the control group, but none in the dose groups. One control group female had three, on other one late resorption sites. Two low group females had one resorption site each.

The number of litters with resorption sites was 11/18 in controls, 7/17 in the low dose and 8/18 in the high dose group.

Early or late resorptions:

not specified

Dead fetuses:

effects observed, non-treatment-related

Description (incidence and severity):

One dead fetus was found in the control group, but none in the dose groups. One control group female had three, on other one late resorption sites. Two low group females had one resorption site each.

Changes in number of pregnant:

not examined

Other effects:

not specified

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
No maternal deaths occurred. Appearance and behavior was comparable to controls. No test substance related gross changes observed in the pregnant animals at necropsy. One animal in the high dose group showed wheezing on day 11. One low dose group animal had sof faeces on day 19.

Dose descriptor:

NOAEL

Effect level:

>= 150 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Dose descriptor:

NOAEL

Effect level:

>= 150 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Fetal body weight changes:

no effects observed

Description (incidence and severity):

The number, weight and length of life foetusses in the test substance groups was comparable to controls.

Reduction in number of live offspring:

not specified

Changes in sex ratio:

not specified

Changes in litter size and weights:

not specified

Changes in postnatal survival:

not specified

Skeletal malformations:

no effects observed

Description (incidence and severity):

Skeletal examinations: skull, ribs, sternum, vertebrae, pelvic gridle, long bones, forepaws, hind paws evaluated. Changes observed occurred with comparable incidence in dose and control groups.

Visceral malformations:

no effects observed

Description (incidence and severity):

Visceral structures were examined by Wilson's sectioning technique in 58 control, 61 low dose and 68 high dose fetuses.

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
All examined parameters were comparable to those of the concurrent controls.

Dose descriptor:

NOEC

Effect level:

150 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Developmental toxicity No test substance related effects observed

Abnormalities:

not specified

Developmental effects observed:

not specified

The number and placement of uterine implantation and resorption sites was comparable in dosed and control group animals.

The number, weight and length of life foetusses in the test substance groups was comparable to controls.

One dead fetus was found in the control group, but none in the dose groups. One control group female had three, on other one late resorption sites. Two low group females had one resorption site each.

The number of litters with resorption sites was 11/18 in controls, 7/17 in the low dose and 8/18 in the high dose group.

A few fetusses in controls and test groups appeared small in size, with similar incidence.

Visceral structures were examined by Wilson's sectioning technique in 58 control, 61 low dose and 68 high dose fetuses.

Observations in all groups included clotted blood in thoracical, abdominal and intestinal, or cranial regions, dilated renal pelvis dilated lateral brain ventricel in one control and ligh colores area of the liver in one control fetus.

No clearly test substance related differences in incidence of findings from controls were observed.

Skeletal examinations: skull, ribs, sternum, vertebrae, pelvic gridle, long bones, forepaws, hind paws evaluated. Changes observed occured with comparable incidence in dose and control groups.

Conclusions:

The developmental toxicity study in rats receiving either 15 or 150 mg/kg bw of the test substance by gavage between day 5 and day 16 of gestation did not reveal any test substance related effects on inplantation, resorption litter size or any fetal parameters investigated in this study. Under the conditions of this study no indications of a possible developmental effect were observed.

Executive summary:

The substance was investigated for enbryotoxic and/or teratogenic effects in goups of 17 to 18 pregnant female albino rats . The test material was mixed with corn oil and administered by oral gavage at dosage levels of 15 and 150 mg/kg/day from Day 6 through Day 15 of gestation . Control animals received corn oil only.

No maternal deaths occurred. All control and test litters were delivered by Caesarean section . Appearance, behavior , body weight gain , and food consumption were comparable among control and test animals. All uterine, litter, and Caesarean data were comparable among control and test groups. There was also no compound-related effect noted with respect to external appearance, visceral anatomy, development , or skeletal structure of the fetuses. Under the conditions of this study no indications of a possible developmental effect were observed.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

A reproduction-developmental screening test according to OECD 421 did not reveal any effects on fertility or embryonic development at the highest recommended dose of 1000 mg/kg bw. The NOAEL for both parental and reproductive toxicity was 1000 mg/kg bw, the highest dose tested.
Two developmental toxicity studies, one in rats and one in rabbits are available. The studies are following a previously accepted test guideline, but were performed in 1970. Only two dose levels were administered by oral gavage. The absence of developmental toxicity is also corroborated by the 3-generation study in rats. The studies in combination give sufficient confidence to conclude that the substance is unlikely to cause adverse effects to the developing embryo or fetus.

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

One screening study and two developmental toxicity studies, one in rats and one in rabbits are available. In the latter groups of pregnant rats or rabbits received either 15 or 150 mg/kg bw per day by gavage from day 6 to 15 and day 6 to 18 of gestation respectively. Concurrent vehicle control animals were included. No test substance related effects on maternal toxicity and embyo fetal development were observed up to the highest dose tested. From the repeated dose studies it can be concluded that the administrerd dose was close to the maximum tolerated dose. The absence of developmental toxicity is also corroborated by the 3-generation study in rats. The studies in combination give sufficient confidence to conclude that the substance is unlikely to cause adverse effects to the developing embryo or fetus.

Consequently, based on the available data the substance is not classidfied for toxicity to reproduction/ developmental toxicity according to regulation 1272/2008 and amendments.

Justification for selection of Effect on developmental toxicity: via oral route:
Weight of evidence from two developmental toxicity studies in rats and rabbits and a 3 generation study in rats.

Toxicity to reproduction: other studies

Additional information

When pregnant rats were given diets containing the substance at concentrations of 0.125 to 1.25% of the dry weight of the food, there were no effects on length of gestation, size of pups, or total number of young per litter. There was not an increase compared to control in numbers of stillborn pups in the litters. This study corroborates the findings of the 2 available teratogenicity studies in rats and rabbits.

Justification for classification or non-classification

Based on the weight of evidence from all available studies, a 3 -generation dietary study in rats, repeated dose dietary studies of 90 -day and 2 year duration in rats and dogs, developmental toxicity studies by gavage in rats and rabbits, and a dietary study in rats covering the prenatal and complete gestation and parturition period in rats, that consistently showed no substance related effects on fertility and/or embryo-fetal development up to the highest dose tested, no classification for reproductive endpoints, neither fertility no developmental toxicity is warranted according to regulation EC 1972/2008 and amendments.