1-[(4-chlorophenyl)methyl]-1-cyclopentyl-3-phenylurea

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Effects on fertility

Description of key information

A guideline- and GLP-compliant 2-generation reproductive toxicity study in the rat with pencycuron is available, and is supported by an older non-guideline study.  A 2-generation reproductive toxicity study is not a REACH information requirement at this tonnage band; however data are available for pencycuron.  Consequently, a screening study is not required and can be waived.

Test Species/Type	Results	Assessment	Reference
None - PNDT study in the rat (25-28/group); 40, 200, 1000 mg/kg bw/d; dosing GD 7-14.	Maternal effects (post-dose sedation) was seen in all treated and control groups, and are attributed to a stress response.  Maternal toxicity was limited to marginal bodyweight effects at 1000 mg/kg bw/d.  There was no evidence of teratogenicity or developmental toxicity.  Total litter loss in two high dose dams was attributed to mis-dosing, which is questionable.	Key study	Inukai and Iyatomi (1978)
OECD 414 (1981) - 200, 600, 2000 mg/kg bw/d; dosing GD 6-18	Litter numbers were low in all groups (14-16).  There was no evidence of teratogenicity, and no maternal or developmental toxicity	Key study	Becker (1983)
OECD 416 (1981) - 2-generation reproductive toxicity study in the rat (100, 1000, 10000 ppm)	A reproductive NOAEL of 10000 ppm was determined for this study, in the absence of any effects on fertility or reproductive capacity.  Parental and offspring NOAELs of 1000 ppm (58 mg/kg bw/d) were determined for this study.	Supporting study	Nagumo et al (1981)
OECD 416 (1981) - 2-generation reproductive toxicity study in the rat (50, 500, 10000 ppm)	A reproductive NOAEL of 10000 ppm was determined for this study, in the absence of any effects on fertility or reproductive capacity.  Parental and offspring NOAELs of 500 ppm (32 mg/kg bw/d) was determined for this study.	Key study	Tauchi (1990)

Link to relevant study records

Reference

Reference 1

Endpoint:

two-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1978-03-01 to 1981-08-04

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Deviations:

no

GLP compliance:

no

Remarks:

older study predates mandatory GLP

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Rats of the Sprague-Dawley strain were purchased in their fourth week of age. After the acclimatization period of one week, they were assigned to experimental groups. The rats were accommodated individually in stainless steel quintuple mesh cages. For mating and during the periods of pregnancy and lactation, they were housed in aluminum breeding cages Throughout the study all rats were maintained in air-conditioned quarters at 23 ± 1°C with 60 ± 10% relative humidity. Lighting was controlled to provide 12 hours of light (07:00 a.m. - 07:00 p.m.) in each 24 hours. Tap water and food were available to the animals ad libitum prior to and during the period of treatment.

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on exposure:

Pencycuron was administered orally at four graded dosage labels, 0, 100, 1,000 or 10,000 ppm in food, which had been determined on the basis of data from a 13-week subacute oral toxicity test with pencycuron in rats. In the test, the highest dosage of 10,000 ppm produced a slight depression of weight gain in female rats and no significant change in males. In view of this as well as from the fact that residue of the pencycuron in food was the principal concern of the present investigation, a concentration of 10,000 ppm above which it would be very unlikely in practice for the compound to remain in any edible material was adopted as the highest dose level. Two other dose levels of 1,000 and 100 ppm, calculated with a common ratio of 1:10, were also employed. A complete powdered rodent food was used as basal diet. From the secondary premix, prepared afresh every three months, the dietary concentration for each group was obtained weekly by direct dilution with an appropriate quantity of food. Each treated group of F0 rats comprised 30 males and 30 females.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

F0 rats of both sexes were treated for 13 weeks prior to mating and throughout mating. Females were treated throughout gestation and lactation of two consecutive litters (F1A, F1B). Selected F1B offspring were treated for 13 weeks prior to mating and throughout mating. Females were treated throughout gestation and lactation of two consecutive litters (F2A, F2B). Treatment of F2B litters continued for 13 weeks.

Frequency of treatment:

Ad libitum.

Details on study schedule:

The durations of observation for respective sets of parameters were as follows:
1) Rearing of F0 rats up to first breeding: 13 weeks
- Duration of first gestation (F1A): 3 weeks
- Duration of nursing for F1A offspring: 3 weeks
(All F1A litters were sacrificed at weaning and not subjected to examinations)
- Resting period of the parents (F0): 10 days
- Duration of second gestation (F1B):
(For teratogenicity test: 20 days
(For parturition: 3 weeks
- Nursing period for F1B offspring: 3 weeks
2) Observation for postnatal growth of F1B offspring: 13 weeks
3) Rearing of F1B rats up to first breeding: 13 weeks
- Duration of first gestation (F2A): 3 weeks
- Duration of nursing for F2A offspring: 3 weeks
(All F2A litters were sacrificed at weaning and not subjected to examinations)
- Resting period of the parents (F1B): 10 days
- Duration of second gestation (F2B):
(For teratogenicity test: 20 days
(For parturition: 3 weeks
- Nursing period for F2B offspring: 3 weeks

Dose / conc.:

0 ppm

Remarks:

Control (basal diet)

Dose / conc.:

100 ppm

Dose / conc.:

1 000 ppm

Dose / conc.:

10 000 ppm

No. of animals per sex per dose:

30

Control animals:

yes

Details on study design:

- Dose selection rationale: basted on 13-week sub-chronic oral toxicity study

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: No data

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION:
- Time schedule for examinations: twice weekly

WATER CONSUMPTION: No

Oestrous cyclicity (parental animals):

Not examined

Sperm parameters (parental animals):

Not examined

Postmortem examinations (offspring):

The following organ weights were recorded for F1B and F2B offspring: brain, heart, lungs, liver, kidneys, spleen, mandibular glands, gonads, thymus, adrenals, pituitary. Histopathology was performed on these organs, and additionally on the thyroids, stomach, gi tract, bone marrow, skeletal muscle and urinary bladder. Terminal blood samples were taken for the assessment of haematological and clinical chemistry parameters.

Statistics:

The significance of any inter-group differences in mean values were assessed by Student's t-test. For analysis of data concerning incidence, the chi square test was employed, with Yates• corrections in case that the frequencies were not greater than 5. In all these analyses the significance level of >5% was adopted. Body weight data from newborn rats were statistically processed as weights per litter.

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The weight gain was slightly depressed in F0 rats of both sexes in the 10,000 ppm dosage group during the post-weaning observation and subsequent breeding periods.
The findings indicate that, when assessed with respect to depression of weight gain, Pencycuron at a concentration of 10,000 ppm is considered to cause a slight effect.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

The mean compound uptake was determined to be 597 to 975 mg/kg/day in the 10,000 ppm dosage group.
In the 10,000 ppm dosage groups, rats of both sexes exhibited an increase, rather than any significant decrease, of average food intake during the post-weaning period of 13 - 14 weeks.

Food efficiency:

effects observed, treatment-related

Description (incidence and severity):

Food efficiency decreased in males and females of the 10,000 ppm dose groups. This might be consequent to the trend of increase in food intake and to that of weight gain depression of the highest-dose groups, compared to the controls.

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Endocrine findings:

not examined

Urinalysis findings:

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Description (incidence and severity):

Neonatal weight gain during the first 3 weeks till weaning was significantly depressed in the 10,000 ppm dosage group on both occasions of reproduction.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 ppm

Based on:

test mat.

Sex:

male/female

Remarks on result:

other: Equivalent to 58 mg/kg bw/d

Key result

Critical effects observed:

no

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

The weight gain was slightly depressed in F1B males in the 10,000 ppm group. Such tendency of weight gain depression was not seen in F1B males or females for breeding groups receiving dosage up to 10,000 ppm. The findings indicate that, when assessed with respect to depression of weight gain, Pencycuron at a concentration of 10,000 ppm is considered to cause a slight effect in rats, but it cannot be regarded as secure toxic dose.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

In the 10,000 ppm dosage groups, rats of both sexes exhibited an increase, rather than any significant decrease, of average food intake during the post-weaning period of 13 - 14 weeks.

Food efficiency:

effects observed, treatment-related

Description (incidence and severity):

The food efficiency decreased in males of the 10,000 ppm dosage groups.

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

A marginal decrease of BUN was observed in F1B rats of the high-dose groups on examinations conducted for 13 - 14 weeks, respectively. The changes were, nevertheless, considered to be within normal limits. Serum enzyme assays (LDH, alkaline phosphatase, GOT and GPT) revealed significantly lowered levels for some of these parameters in the highest-dose group, which were not so conspicuous as to provide any evidence for damage of liver cells or cells of other tissues.

Endocrine findings:

not examined

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Examination of the urine revealed a slightly positive test for urobilinogen in both F1B males and females in the 10,000 ppm dosage group.

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Organ weight analyses, conducted on the F1B rats at the 13 week, revealed a tendency of increase in liver and kidney weights in males of both generations in the 10,000 ppm groups. Liver and kidney weights of females showed a similar trend to increase.
In the present series of tests, pencycuron demonstrated no evidence of producing any adverse effects on the reproductive performance or of being teratogenic in rats of the strain used.
Observations of the offspring made for any influence of the administration of pencycuron on their postnatal development disclosed a slight depression of weight gain and a marginal increase in liver and kidney weights in the 10,000 ppm dosage group, as general toxicologic effects of the compound. From these findings, the maximum non-effect level of the compound is estimated to be 1,000 ppm.

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 ppm

Based on:

test mat.

Sex:

male/female

Remarks on result:

other: equivalent to 58 mg/kg bw/d

Key result

Critical effects observed:

no

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality / viability:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Neonatal weight gain of the F1 generation during the first 3 weeks till weaning was significantly depressed in the 10,000 ppm dosage group on both occasions of reproduction.

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:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not examined

Anogenital distance (AGD):

not examined

Nipple retention in male pups:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

Teratogenicity tests conducted on the rats of F1B and F1B generations revealed no significant difference between any treated groups and the control group in respect of mean numbers of corpora lutea, live fetuses and embryonal or fetal deaths, sex ratio of the fetuses, mean live fetal weight or incidence of external morphological abnormalities. There was sporadic incidence of skeletal and visceral abnormalities, but their distribution did not provide any evidence of reaction to treatment with pencycuron.

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

1 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Key result

Critical effects observed:

no

Clinical signs:

no effects observed

Description (incidence and severity):

No signs of adverse changes in general physical condition which might be ascribed to the administration of pencycuron were noted in rats during the observation period after weaning.

Dermal irritation (if dermal study):

not examined

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

In the 10,000 ppm dosage groups, both males and females showed an increase, rather than any significant decrease, of mean food consumption from the 13 to 14 weeks after weaning.

Food efficiency:

no effects observed

Description (incidence and severity):

The food efficiency decreased in male and females of the 10,000 ppm dosage groups.

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

A marginal decrease of BUN was observed in F2B rats of the high-dose groups on examinations conducted for 13 - 14 weeks, respectively. The changes were, nevertheless, considered to be within normal limits for this species. Serum enzyme assays (LDH, alkaline phosphatase, GOT and GPT) revealed significantly lowered levels for some of these parameters in the highest-dose group, which were not so conspicuous as to provide any evidence for damage of liver cells or cells of other tissues.

Urinalysis findings:

effects observed, treatment-related

Description (incidence and severity):

Examination of the urine revealed a slightly positive reaction for ketones in F2B rats of both sexes in the 10,000 ppm dosage group at the 14th week of feeding, as a general trend.

Sexual maturation:

not examined

Anogenital distance (AGD):

not examined

Nipple retention in male pups:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Organ weight analyses, conducted on the F2B rats at the 14 week, revealed a tendency of increase in liver and kidney weights in males of both generations in the 10,000 ppm groups. Liver and kidney weights of females showed a similar trend to increase. In the present series of tests, pencycuron demonstrated no evidence of producing any adverse effects on the reproductive performance or of being teratogenic in rats of the strain used. Observations of the offspring made for any influence of the administration of pencycuron on their postnatal development disclosed a slight depression of weight gain and a marginal increase in liver and kidney weights in the 10,000 ppm dosage group, as general toxicologic effects of the compound. From these findings, the maximum non-effect level of the compound is estimated to be 1,000 ppm.

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

Teratogenicity tests conducted on the rats of F2B generation revealed no significant difference between any treated groups and the control group in respect of mean numbers of corpora lutea, live fetuses and embryonal or fetal deaths, sex ratio of the fetuses, mean live fetal weight or incidence of external morphological abnormalities. There was sporadic incidence of skeletal and visceral abnormalities, but their distribution did not provide any evidence of reaction to treatment with the pencycuron.

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

Key result

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

1 000 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

Key result

Critical effects observed:

no

Key result

Reproductive effects observed:

no

Lowest effective dose / conc.:

1 000 ppm

Treatment related:

no

Conclusions:

A 2-generation study in rats (Sprague-Dawley) was submitted using dose levels of 0, 100, 1000, 10000 ppm. No adverse treatment-related reproductive effects were observed in any of the dose groups.

Executive summary:

A study with pencycuron were performed in rats of two consecutive generations (2 litters per generation). Pencycuron was administered orally by incorporation into diet at concentrations of 0 (controls), 100, 1000 or 10000 ppm.  F0 rats (30/sex) were exposed to diet containing pencycuron, from 5 weeks of age, and were mated on two separate occasions after the 13th week of dosing. The F1A and F2A offspring were at weaning; detailed examinations were made on all F1B and F2B litters, which were sacrificed after treatment for 13 weeks.  Pencycuron showed no evidence of causing disturbance in reproductive performance at any dose level under the conditions of this study.

Reference 2

Endpoint:

two-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988-09-16 to 1990-05-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Version / remarks:

1981

Deviations:

yes

Remarks:

Study performed to the OECD 416. It differs from the current guideline with: the performance of histopathological examination of the pups and the organ weight of brain, pituitary, thyroid and adrenal glands, prostate and seminal vesicles.

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Wistar

Remarks:

SPF animal

Details on species / strain selection:

Standard laboratory species/strain with background data available.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 5 wks
- Weight at study initiation: Males: 50-80 g; Females: 45-75 g.
- Housing: Animals were housed in a barrier-sustained animal room.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 8 days.

ENVIRONMENTAL CONDITIONS
- Temperature: 22-26°C
- Humidity: 45-65%
- Air changes (per hr): 12
- Photoperiod: lighted 14 hours per day.

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Remarks:

For each dose level, pencycuron was weighed and mixed with basal diet to obtain the prescribed concentration.

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
For each dose level, pencycuron was weighed and mixed with basal diet to obtain the prescribed concentration. The mixture was stirred by a SS-501 mixer.

DIET PREPARATION
- Rate of preparation of diet (frequency): once every 2 weeks

Details on mating procedure:

- M/F ratio per cage: 1/1
- Proof of pregnancy: existence of plugs or sperms in vaginal smear referred to as day 0 of pregnancy.
- After successful mating each pregnant female was caged: Maternal animals were housed individually in polypropylene cages with appropriate bedding.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Before the start of study, stability (for 4 weeks) and homogeneity of pencycuron in diet were confirmed by analysis. A part of the test diet of each dose level, sampled every 3 months, was analyzed for concentration of pencycuron. The results of the chemical analyses of the test diets used in the present study were satisfactory, indicating that there were no abnormal values influencing the evaluation of this study.

Duration of treatment / exposure:

The test diet or basal diet (controls) was administered for the entire study period. Male and female animals were treated for at least 10 weeks prior to mating and throughout mating. Females were treated during gestation and lactation. Offspring were treated from weaning.

Frequency of treatment:

Continuously via dietary administration

Details on study schedule:

- F1 parental animals not mated until 13 weeks after selected from the F1 litters.
- Selection of parents from F1 generation when pups were 5 weeks of age.
- Age at mating of the mated animals in the study: 13 weeks

Dose / conc.:

0 ppm

Remarks:

Control

Dose / conc.:

50 ppm

Dose / conc.:

500 ppm

Dose / conc.:

10 000 ppm

No. of animals per sex per dose:

27/sex/group

Control animals:

yes

Details on study design:

- Dose selection rationale: Dose levels and group size were determined based on the information of preliminary toxicological studies.

Parental animals: Observations and examinations:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: All animals were observed daily for general condition and appearance. Any abnormalities were recorded individually with their onset, duration and severity when necessary.
Dead animal was autopsied upon discovery so as to examine the cause of the death.

BODY WEIGHT: Yes
- Time schedule for examinations: Males and females were weighed once a week until termination of study. Maternal animals were weighed on days 0, 7, 14 and 21 of gestation, and on days 0 (day of delivery), 4, 7, 14 and 21 of lactation.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food intake of males and females were individually measured once a week for all cages except for mating period. Mean food intakes (g/day /rat) were individually calculated by dividing total intake by the days between measurement points.

Intake of pencycuron (mg/kg/day) for a cage or an animal was calculated as follows:
Test substance intake= Concentration(ppm) in diet X Mean food intake (g/day/rat)/ Mean body weight(g) between measurement points.

OTHER:
Observations during reproductive period:
- Pre-mating period: Vaginal smear was examined daily using Giemsa-stain method from 2 weeks before mating to day 0 of gestation or to the termination of mating period.
- Perinatal period: Abortion, premature birth and dystocia were checked.
- At birth: Duration of gestation was calculated. Number of live and dead newborns, their sex, and their external abnormalities were observed. The pups were skin or hair-dyed with methylviolett for individual identification.
- Nursing period: Nursing conditions of dams and mortalities of pups were observed every day.
- Body weight of pups: Individual body weight of pups per dam for each sex was measured on days 0, 4, 7, 14 and 21 post partum, and mean pups body weight for each sex was calculated.

Postmortem examinations (parental animals):

- Autopsy: For all the parental animals (sacrificed to schedule as well as found dead), complete gross examination was done.
- Period of autopsy:
Parental females: Day of weaning.
Parental males: After parental female's 2nd delivery.
- Organ weights: For all the parental animals of P and F1 generations following organs were weighed. liver, kidneys, spleen, ovaries, testes
- Fixation of organs: Following organs of all the parental animals of P and F1 generations were fixed and preserved in 10% buffered formalin solution.
liver, kidneys, spleen, brain, pituitary, vagina, uterus, mammary gland, ovaries, epididymis, seminal vesicle, prostate, testes and organs or tissues with gross lesion.
- Histopathological examinations were performed for all fixed specimens of P and F1 parental animals of control and the highest dose group and of non-copulated or non-pregnant animals in the low and medium dose groups. The specimens were processed to obtain ordinary hematoxylineosin-stained sections for microscopic examination. Further, livers in the 50 ppm and 500 ppm groups were also examined microscopically, because changes in the liver were found in the highest dose group, it seemed that the changes were caused by treatment of pencycuron.

Postmortem examinations (offspring):

Pathological examinations:
- Autopsy: For all weanlings, complete gross examination was done.
- Period of autopsy:
Weanlings: Day of weaning.
Surplus pups at culling: Day 4 of lactation.

Statistics:

The significance of differences between the control and each dose group was analyzed by Student's t-test (the Aspin-Welch's modification was used if homogeneity of variance is not obtained by F-test), chi-square test, Wilcoxon's rank-sum test and Fisher's exact fit test. Difference of P<0.05 was considered significant.

The statistical tests applied are as follows:
Student's t-test: Body weight of parental animal, food intake, organ weight(absolute and relative), number of newborn, pup's body weight; Chi-square test: Sex ratio, mating index, gestation index, birth index, duration of gestation; Wilcoxon's rank-sum test: Day 4 and 21 survival indices of pups; Fisher's exact fit test: Incidence of organs or tissues with abnormality and of newborns with external abnormality.

Reproductive indices:

Mating index = (number of animals copulated/ number of animals cohabited) x 100
Gestation index = (number of pregnants/ number of females copulated) x 100
Birth index = (number of dams with live newborns/ number of pregnants) x 100
Sex ratio = number of live male newborns/ number of live female newborns

Offspring viability indices:

Day 4 survival rate = (number of live pups on day 4/ number of live newborns )x 100
Day 21 survival rate= (number of live pups on day 21/ number of pups after culling on day 4) x 100

Clinical signs:

no effects observed

Description (incidence and severity):

Throughout the study, neither toxic signs nor changes in general conditions attributable to pencycuron were observed in both sexes.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

In the 10,000 ppm group of the P generation, one dam (F213) died due to foreign body pneumonia resulting from inhaling food and nesting material.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

In the 10,000 ppm group, body weights of both sexes of the P generation showed significantly lower gain as compared with those in control group. Significantly lower values were found at the following intervals: in males of the P generation, during weeks 1-13 and 15-19 of treatment; in females of the P generation, during weeks 1-11 of treatment and most part of the generation and lactation period.

In the 500 ppm group, significantly lower body weights were also observed in both sexes of the P generation at the following intervals; during weeks 1-3 of treatment in males; and during weeks 1-4 of treatment and on day 21 of lactation of 1st and 2nd parity in females. In the 50 ppm group, although statistically significant changes were sporadically found at some intervals, but there were no dose-response relationships.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

In the 10,000 ppm group, significant decreases of food intakes was observed in both sexes of the P generation at the following intervals: in the P generation, during weeks 0-3 of treatment in males; during weeks of treatment 0-1 and periods of 1st lactation and 2nd gestation. In the 500 ppm group, significantly lower food intakes were observed in animals of the P generation at the following intervals: during weeks 0-2 of the treatment in males of the P generation. In the 50 ppm group, significant differences were sporadically found at some intervals in both sexes. However, these changes were considered to be unrelated to pencycuron treatment, because there were no dose-response relationships and these changes were transient.

The mean intakes of pencycuron were : 3.2-3.4 mg/kg/day in males and 4.6-4.9 mg/kg/day in females of 50 ppm group; 32.7-34.0 mg/kg/day in males and 48.7 mg/kg/day in females of 500 ppm group ; and 676.4-704.3 mg/kg/day in males and 998.5-1000.6 mg/kg/day in females of 10000 ppm group.

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

Endocrine findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

In the 10,000 ppm group, centrilobular hepatocellular swellings were observed in both sexes of the P generation. No such changes were detected in any animal of the 500 ppm and 50 ppm groups. With respect to other organs, sporadic and slight findings were observed in both sexes. However, there were no significant differences in incidence between the control and treated groups. As to the infertile animals, no histopathological abnormalities were detected in their reproductive organs.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Reproductive function: oestrous cycle:

no effects observed

Description (incidence and severity):

No abnormality in regularity of the oestrous cycle was observed.

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Description (incidence and severity):

No abnormality was observed, and indices of mating and fertility in any treated groups were comparable to those in the control group. With respect to the data on parturition, stillbirth was noted in one dam in control group of the P generation, and 4 dams in control , 2 dams in 500 ppm. There were no dose-response relationships. And the duration of gestation in the treated groups of any generations and parities as comparable to that in the control group. In all treated groups, when the mean number of live pups, sex ratio and survival index on the day of delivery were compared to those in the control group, no significant differences attributable to pencycuron were obtained.

Key result

Dose descriptor:

NOAEL

Effect level:

500 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

organ weights and organ / body weight ratios

Remarks on result:

other: Equivalent dose levels for males (3.2-3.4 mg/kg/day), females (4.6-4.9 mg/kg/day)

Key result

Critical effects observed:

no

Clinical signs:

no effects observed

Description (incidence and severity):

Throughout the study, neither toxic signs nor changes in general conditions attributable to pencycuron were observed in both sexes.

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Description (incidence):

There were no deaths attributable to treatment

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

In the 10,000 ppm group, body weights of both sexes of F1 generation showed significantly lower gain as compared with those in control group. Significantly lower values were found at the following intervals: F1 males , during weeks 0-15 of treatment; in F1 females, during weeks 0-6 of treatment, on days 4,7 and 14 lactation of the 1st parity , on days 7 and 14 of lactation of the 2nd parity.

In the 500 ppm group, the body weights of F1 animals of both sexes in the 500 ppm group were comparable to those in the control group.

In the 50 ppm group, although statistically significant changes were sporadically found at some intervals, there were no dose-response relationships.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

In the 10,000 ppm group, significant decreases of food intakes was observed in F1 generation at the following intervals: in F1 generation, during weeks 0-7 of treatment in males; during the gestation and lactation periods of the 1st litter and the lactation period of the 2nd litter in females. In the 500 ppm group, significantly lower food intakes were observed in animals of the F1 generation at the following intervals: during the gestation periods of 1st and 2nd parity in F1 females. In the 50 ppm group, significant differences were sporadically found at some intervals in both sexes. However, these changes were considered to be unrelated to the pencycuron treatment, because there were no dose-response relationships and these changes were transient.

The mean intakes of pencycuron: 3.2-3.4 mg/kg/day in males and 4.6-4.9 mg/kg/day in females of 50 ppm group; 32.7-34.0 mg/kg/day in males and 48.7 mg/kg/day in females of 500 ppm group; and 676.4-704.3 mg/kg/day in males and 998.5-1000.6 mg/kg/day in females of 10,000 ppm group.

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

Endocrine findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

Absolute and relative liver weights of both sexes in the 10,000 ppm group were significantly higher than those in the control group. And the absolute and relative spleen weights in both sexes treated with 10,000 ppm were significantly lower. In the 500 ppm group, the absolute and /or relative liver weights were likewise higher in both sexes of F1 females. In the 50 ppm group, liver and spleen weights were comparable to those in the control values. With respect to the other organs, the following changes were sporadically observed: in the 50 ppm group, an increase in the spleen (absolute and relative) and kidneys (absolute) in F1 males. However, there were no dose- response and consistent tendencies.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

As a sporadic change, slight abnormalities in some organs of a few animals in any generations were observed, however , there were no significant differences in incidence between the control and treated groups.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

In the 10,000 ppm group, centrilobular hepatocellular swellings were observed in both sexes of F1 generation. No such changes were detected in any animal of the 500 ppm and 50 ppm groups.
With respect to other organs, sporadic and slight findings were observed in both sexes. However, there were no significant differences in incidence between the control and treated groups. As to the infertile animals, no histopathological abnormalities were detected in their reproductive organs.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Description (incidence and severity):

No abnormality in regularity of sexual cycle was observed, and indices of mating and fertility in any treated groups were comparable to those in the control group. With respect to the data on parturition, stillbirth was noted in one dam in control group of the P generation, and 4 dams in control , 2 dams in 500 ppm. There were no dose-response relationships. And the duration of gestation in the treated groups of any generations and litters was comparable to that in the control group. In all treated groups, when the mean number of live pups, sex ratio and survival index on the day of delivery were compared to those in the control group, no significant differences attributable to pencycuron were obtained.

Key result

Dose descriptor:

NOAEL

Effect level:

500 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

organ weights and organ / body weight ratios

Remarks on result:

other: Equivalent dose levels for males (3.2-3.4 mg/kg/day), females (4.6-4.9 mg/kg/day)

Key result

Critical effects observed:

no

Clinical signs:

no effects observed

Description (incidence and severity):

Throughout the study, neither toxic signs nor changes in general conditions attributable to pencycuron were observed in both sexes.

Dermal irritation (if dermal study):

not examined

Mortality / viability:

mortality observed, non-treatment-related

Description (incidence and severity):

Significantly lower values of F1A pup survival rate were observed on day 4 of 1st lactation in the 500 and 10000 ppm groups. However , this change was evaluated to be incidental, since the values for the F1B litters were comparable to those in the control group.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

In the 10,000 ppm group, body weights of both sexes of F1 generation showed significantly lower gain as compared with those in control group. Significantly lower values were found at the following intervals: F1 males , during weeks 0-15 of treatment; in F1 females, during weeks 0-6 of treatment.

In the 500 ppm group, the body weights of F1 animals of both sexes in the 500 ppm group were comparable to those in the control group.

In the 50 ppm group, although statistically significant changes were sporadically found at some intervals, there were no dose-response relationships.

With respect to the pup's body weights, significantly lower values were observed in F1a and F1b offspring in the 10,000 ppm group.

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:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not examined

Anogenital distance (AGD):

not examined

Nipple retention in male pups:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

In the weanlings, the following findings were observed: in the control group , one case of absent in kidney and uterine horn (F1a female) and one case of absent in kidney (F1b male); in the 50 ppm group, one case of hydronephrosis (F1a male); in the 500 ppm group, 5 cases of hydronephrosis (F1a male: 1 case) and one case of hypoplasia in kidney (F1a female). However, there was no dose-response relationship in incidence.

Histopathological findings:

not examined

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

As an external abnormality of newborns, one F1a pup with short tail in control group, one F1b pup with tailless in 500 ppm group were observed, but the incidences were very low in each case.

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

500 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Clinical signs:

no effects observed

Description (incidence and severity):

Throughout the study, neither toxic signs nor changes in general conditions attributable to pencycuron were observed in both sexes.

Dermal irritation (if dermal study):

not examined

Mortality / viability:

mortality observed, non-treatment-related

Description (incidence and severity):

Significantly lower values of pup's survival rate were observed on day 4 of 1st lactation (F2a) in the 500 and 10000 ppm groups. However, this change was evaluated to be incidental, since the values of 2nd parity (F2b) were comparable to those in the control group.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

With respect to the pup's body weights, significantly lower values were observed in F2a and F2b offspring in the 10,000 ppm group. In the 500 ppm group, similar lower changes were also observed in F2a and F2b offspring.

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:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not examined

Anogenital distance (AGD):

not examined

Nipple retention in male pups:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

effects observed, non-treatment-related

Histopathological findings:

not examined

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

As an external abnormality of newborns, one F2b pup with manus valga in 10,000 ppm group was observed, but the incidences were very low in each case.

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

Key result

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

500 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

Key result

Critical effects observed:

no

Key result

Reproductive effects observed:

no

Conclusions:

Pencycuron did not influence the reproductive performance of the animals at dietary concentrations of up to and including 10,000 ppm (676.4-704.3 mg/kg/day in males and 998.5-1000.6 mg/kg/day in females).

Executive summary:

To investigate the potential effects of pencycuron on reproductive performance and growth of offspring, doses of 0, 50, 500 and 10,000 ppm owere administered to two successive generations of Wistar rats. Mating was performed 2 times for both the P (F0) and F1 generation; F1 parental animals were selected from the F1b offspring.  At 10,000 ppm, food intake and bodyweights of the parental groups were decreased. Body weights of the P generation at 500 ppm were also significantly decreased (by up to 5%) within the first week of treatment; findings are considered to be due to poor palatability.  Similarly, The F1 generation at 500 ppm initially had slightly lower body weights than the controls but compensated later.  Body weight gain of of the F0 generation at 500 ppm was reduced after the first two weeks (by up to 10%), but thereafter the animals gained weight comparable to controls and largely compensated the initial body weight reduction. In a parallel feeding test, food consumption was reduced up to 6% at the start of treatment. Overall it is concluded that changes in body weight (gain) and food consumption are considered to be due to palatability effects and are not considered toxicologically relevant.  The liver of rats of both generations and sexes was the organ which was influenced by pencycuron on both, microscopical and macroscopical level. At 10000 ppm pencycuron, significantly increased absolute and relative liver weight and an increased incidence of centrilobular hepatocellular hypertrophy were identified.  At 500 ppm, liver weight was increased for females in both generations and male animals of the F0 generation. The increase in absolute (5%) and relative (5%) mean liver weight in F0 males was only slight (5 and 6% of controls, respectively). In females, the increase in absolute and relative liver weight in F1 females was 11%, while the relative liver weight was increased only 7%. Changes are considered to be partly due to high variations in absolute liver weights in both control groups (F0 and F1), whereas body weights were comparable.  No macroscopic or histopathological correlates for liver effects up to and including 500 ppm were noted.  The body weight of pups was decreased in the highest dosing groups for both generations and at the 500 ppm dosing group for the F2-pups. However, body weights of F2a and F2b pups were within the normal range, but were lower than the unusually high control pup weights. These were mainly caused by smaller litter sizes, complete loss of potentially weak pups, and/or selection of the smallest pups for culling in the control groups. Observed changes in pup body weight at 500 ppm were therefore not considered toxicologically relevant.  Pencycuron did not influence the reproductive performance of the animals; the reproductive NOAEL is therefore 10,000 ppm. Based on, respectively, decreased body weight of the pups, and on decreased body weight and increased liver weight in the parents at the next higher dose, a dose of 500 ppm pencycuronis the NOAEL for parental and offspring effects.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

A guideline- and GLP-compliant 2-generation reproductive toxicity study in the rat with pencycuron is available, and is supported by an older non-guideline study. 

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Effects on developmental toxicity

Description of key information

The developmental toxicity of pencycuron has been investigated in GLP- and guideline-compliant studies in two species (rat and rabbit).  There was no evidence of developmental toxicity in either of these studies.

Link to relevant study records

Reference

Reference 1

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1982-08-03 to 1990-02-27

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

1981

Deviations:

yes

Remarks:

The study was performed in accordance with OECD 414 (1981), except the macroscopic examination of the dams, which was not carried out. The dams were killed on day 28 of pregnancy and the foetuses removed by caesarean section.

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rabbit

Strain:

Chinchilla

Details on test animals or test system and environmental conditions:

Species Rabbits, Chinchilla hybrid
Reasons for selection This system has been selected as standard non-rodent species (according to guidelines) and is internationally recognized for this type of investigation.
Initial age (at mating) between 4 and 6 months
Initial body weight (at test start) 2409 - 4187 g
Acclimation 1 week under test conditions, minimum.
Number of animals 64 mated females, 16 per group
Identification Individually numbered on the inner surface of the pinna by an indelible felt tip pencil.
Accommodation During the whole experiment the animals were housed individually in a "Ehret-Battery".

CONDITIONS:
The experiment was conducted under optimal hygienic conditions (OHC).
The animal room was air-conditioned with:
temperature: 22 +/- 2 degrees centigrade,
relative humidity, 55 +/- 10 %, and
light cycle: 12 hours/day
changes of air approx. 12 times/hour.
Neither insecticides nor chemicals were applied in the animal room with the exception of a disinfectant for floor and wall cleaning once a week.
DIET:
The diet consisted of pelleted standard Kliba 341 rabbits maintenance diet, ad libitum, defined for contaminant level. Certificates for the analyses of contaminants are attached.
WATER:
Tap water was available ad libitum.

Route of administration:

oral: gavage

Vehicle:

other: As vehicle distilled water with 0.25 % cremophor EL* (BASF) was applied; all groups 8 ml/kg body weight. * Cremophor EL is a emulgator with a particular good physiological digestibility.

Details on exposure:

Route of administration Oral by intubation. As vehicle distilled water with 0.25 % cremophor EL was applied; all groups 8 ml/kg body weight.
Reason for selection International guidelines recognize the efficacy of this administration method.
Preparation of the pencycuron suspension The suspension of the pencycuron was prepared daily by homogenizer and/ or magnetic stirrer. The vehicle was 0.25 % cremophor in distilled water.
Stability of the pencycuron
Prior to the initiation of the study, a chemical analysis of the stability of the pencycuron in the suspension was performed.
Concentration of the pencycuron suspension
Determination of concentration of the pencycuron suspension was performed during the study.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analytical tests for determination of the stability and concentration of the applied suspension were performed during the study. The analytical methods used to confirm the stability of the test and control material were supplied by the sponsor.

Details on mating procedure:

Females were mated with males of proven fertility in the ratio of 1 male 1 female. If practicable, each female was mated twice~ the second time as soon as possible by the same male within about 1 hour. The day of observed mating was day 0 after mating.

Duration of treatment / exposure:

Once daily.

Frequency of treatment:

From day 6 through day 18 after mating.

Duration of test:

30 days

Dose / conc.:

0 mg/kg bw/day

Dose / conc.:

200 mg/kg bw/day

Dose / conc.:

600 mg/kg bw/day

Dose / conc.:

2 000 mg/kg bw/day

No. of animals per sex per dose:

15

Control animals:

yes

Details on study design:

- Dose selection rationale: Preliminary study. The dose levels were chosen based on a preliminary range-finding study (reference not given). In that study concentrations of 100, 300 and 1000 mg/kg body weight were applied and no dose-related effects on dams and foetuses were found.
- Rationale for animal assignment (if not random): Random.

Maternal examinations:

Body weight daily; The individual body weight gain was defined as the difference between weights on the first day of treatment and the day of necropsy, respectively. Maternal body weight on the day of necropsy was corrected by subtracting the weight of the gravid uterus from the total body weight. Non-gravid females were excluded from the calculation of the average weight gain.

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily.

DETAILED CLINICAL OBSERVATIONS: Yes / No / No data
- Time schedule:

BODY WEIGHT: Yes
- Time schedule for examinations: day 1 of pregnancy and day of necropsy.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- 6, 11, 15, 19, 24 and 28 of pregnancy

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

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 28
- Organs examined: not specified.

Ovaries and uterine content:

Termination of the study
On day 28 of pregnancy, dams were killed by cervical dislocation and fetuses removed by caesarean section.
The investigations of dams and fetuses were performed in accordance with international standard procedures. Following examination of the organs, ovaries (number of corpora lutea) uterus and uterus contents, the fetuses were identified by uterine position and removed weighed and examined for external abnormalities.

Fetal examinations:

The fetuses were submitted to one of the following procedures individually.
1) Evaluation of the situs of the body cavities (thorax, abdomen , pelvis), sex were noted.
2) Investigations of the cephalic viscera and brain according to the slicing technique of Wilson. Heads of fetuses were fixed in a mixture of trichloroacetic acid and formal.
3) Skeletal investigations of the trunks of fetuses including limbs after clearing in potassium hydroxide and staining with alizarine red; slightly modified technique of Dawson·
Archivation of slices and skeletals
1) Slicing technique of Wilson: After investigations, slices of the fetuses heads are preserved in a mixture of ethyl alcohol and glycerine in the ratio 1,3, one fetus/bottle.
2) Alizarine red skeletal staining: The individual fetuses are preserved in plastic bags after investigation.

Statistics:

Mean values and standard deviations were applied, whenever feasible. For the sex ratio of fetuses, the 2 x 2 chi-square test was applied.

Clinical signs:

no effects observed

Description (incidence and severity):

No toxic signs or clinical symptoms were evident in the females of all groups.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

The treatment with the pencycuron caused no mortality. The death of one female in the high dose group (day 20 p. c.) is considered a random occurrence. Macroscopic examination did not reveal the cause of death.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Similar mean body weights in all groups during the treatment period.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Similar mean food consumption in all groups during the treatment period and also during the periods without treatment.

Number of abortions:

effects observed, non-treatment-related

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Details on maternal toxic effects:

No treatment related differences between the means of all groups. The differences existing were within the normal range of biological deviations for animals of this strain and age.

Key result

Dose descriptor:

NOAEL

Effect level:

2 000 mg/kg bw/day

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Abnormalities:

no effects observed

Changes in litter size and weights:

effects observed, non-treatment-related

Description (incidence and severity):

No treatment related differences between the means of all groups. The higher mean body weight of the high dose group fetuses is caused by a smaller number of fetuses per dam.

External malformations:

no effects observed

Description (incidence and severity):

No findings in all groups with exception of one fetus with partial hyperemic skin in the intermediate dose group.

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Vehicle control group: One fetus (0.8%), sternebrae 3-5 fused. One fetus (0.8%), distal part of all ribs irregular ossified (hyperplasia) One fetus (0.8%), rib 9+10, right, dorsal fusion.
200 mg/kg group: unilateral, one fetus (0.9%) , double rib.
600 mg/kg group: no findings.
2000 mg/kg group: one fetus (0.7%), rib shortened; one fetus (0.7 %), partial absence of a vertebra, rib shortened; one fetus (0.7%), split vertebra, rib(s) fused and/or partial absent or shortened.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Vehicle control group: Three fetuses, discolored (brown) lung. One fetus, discolored (white) liver, distal area. All fetuses of the same dam.
200 mg/kg group: no findings.
600 mg/kg group: no findings.
2000 mg/kg group: One fetus, aplasia of left ovary.

Other effects:

no effects observed

Description (incidence and severity):

Cephalic viscera investigations by Wilson Technique: No findings in all groups.

Key result

Dose descriptor:

NOAEL

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Abnormalities:

no effects observed

Key result

Developmental effects observed:

no

Table showing the mean body weight gains during the treatment period.

Dose Group	Mean body weight gain Day 6 - 19 p.c.
vehicle control 0 mg/kg	306 g 9.7%
200 mg/kg	316 g 9.9%
600 mg/kg	361 g 11.4%
2000 mg/kg	288 g 8.9%

Table showing the mean reproduction data of dams.

Dose Group	Corpora lutea	Implantations	Living fetuses	Resorptions (embr.)	Resorptions (fetal)
vehicle control 0 mg/kg	11.2	9.6	8.33	0.53	0.73
200 mg/kg	10.64	8.86	8	0.14	0.71
600 mg/kg	10.88	10	9.19	0.38	0.44
2000 mg/kg	9.19	7.5	6.94	0.25	0.31

Table showing the mean body weights of fetuses (males and females).

Dose Group	Mean body weights of fetuses (males and females)
vehicle control 0 mg/kg	33.10 g = 100 %
200 mg/kg	35.00 g = + 5.7 %
600 mg/kg	33.30 g = + 0.6 %
2000 mg/kg	38.30 g = + 15.7 %

 

Conclusions:

Acceptability
The number of pregnant animals in the control and the lowest dosing group is just below the minimum of 16 as requested in the now valid guideline (OECD guideline 414, 2001). These deviations are not considered to have major impact on the outcome of the study. The study is considered acceptable for evaluation.

Conclusions
The only effect of pencycuron found in this teratogenicity study in rabbits was an increased foetal weight in the highest dosing group. This effect was only significant if based on litter, not if based on individual animals. Therefore it is not considered as relevant. No treatment related maternal effects were found. Based on these findings both the NOAEL(maternal) and the NOAEL(developmental) are set at the highest concentration tested, 2000 mg/kg bw/day. No indication of a teratogenic potential of pencycuron in rabbits was found.

Executive summary:

PRELIMINARY STUDY
In the preliminary study, 100, 300, and 1000 mg/kg bw were applied. For each dose, two mated females were taken. The results were as follows: No death occurred. No clinical signs or symptoms were evident. No dose-related differences were found in body weight, food consumption, reproduction, malformations and/or anomalies by external investigations, situs investigations of body cavities.

CONCLUSION
Because there were no effects on dams and fetuses in all dose groups, the dose levels for the main study were doubled to 200, 600 and 2000 mg/kg body weight.

The purpose of this study was to assess the embryotoxic and/or teratogenic potential of pencycuron when administered orally to mated chinchilla rabbits (hybrids) at:
Group 1: 0 mg/kg bodyweight/day (vehicle control)
Group 2: 200 mg/kg bodyweight/day
Group 3: 600 mg/kg bodyweight/day
Group 4: 2000 mg/kg bodyweight/day
on days 6 through 18 after mating (16 mated female rabbits per group). These dosages were chosen because of results of the preliminary study.

DATA OF DAMS
Mortality No treatment-related death occurred in the females of all groups
Signs and symptoms No signs of toxicity or clinical symptoms were observed in the females of all groups.
Food consumption No treatment-related differences of food consumption means were evident between all groups.
Body weights No treatment-related differences in body weight means or body weight gain means were evident between all groups.
Reproduction data No treatment-related differences in the means of reproduction data were evident between all groups.

DATA OF FETUSES
Body weights No treatment-related differences of mean body weights were evident between all groups.
Malformations and/or anomalies by external investigations No treatment-related differences were evident between all groups.
Situs investigations of body cavities No treatment-related differences were evident between all groups.
Skeletal investigations No treatment-related differences were evident in all groups.
Cephalic viscera investigations by Wilson Technique No findings in all groups.
Assessment of pencycuron did not reveal any teratogenic or embryotoxic potency in chinchilla rabbits, under the described conditions of this study. The findings and differences observed were within the limit of biological variations of this rabbit strain.

CONCLUSION

The only effect of pencycuron found in this teratogenicity study in rabbits was an increased foetal weight in the highest dosing group. This effect was only significant if based on litter, not if based on individual animals. Therefore it is not considered as relevant. No treatment related maternal effects were found. Based on these findings both the NOAEL(maternal) and the NOAEL(developmental) are set at the highest concentration tested, 2000 mg/kg bw/day. No indication of a teratogenic potential of pencycuron in rabbits was found.

Reference 2

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1977-07-01 to 1978-09-01

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Principles of method if other than guideline:

- Principle of test: Pre-guideline study of teratogenicity in the rat
- Short description of test conditions: Groups of rats were dosed on GD 7-14, and sacrificed on GD 20
- Parameters analysed / observed: Fetuses were assessed for external, visceral and skeletal findings

GLP compliance:

no

Remarks:

older study predates mandatory GLP

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

Sprague-Dawley rats purchased at ten weeks of age from Japan CLEA Ltd., Tokyo, were used. After an acclimatization period of 2 weeks, each female was caged overnight with a male in a breeding cage for mating. When a vaginal plug was found on the tray at the bottom of the cage or formation of the vaginal plug was noted in the female on the following morning, the doe was assigned to an experimental group, the day of finding the vaginal plug being taken as Day 0 of gestation.

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Details on exposure:

Pencycuron was suspended in polyethylene glycol #400 at concentrations as to allow administration of the assigned dosage in 0.5 ml of suspension per 100 g of body weight. Dosages were administered intragastrically by stomach tube once daily from Days 7 to 14 of pregnancy. Dosing was begun at 1:00 p.m. each day. The animals received the test compound at dose levels of 40) 200 or 1,000 mg/kg and controls received an equivalent amount of the vehicle alone.

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

8 days

Frequency of treatment:

1 per day

Duration of test:

20 days

Dose / conc.:

0 mg/kg bw/day

Dose / conc.:

40 mg/kg bw/day

Dose / conc.:

200 mg/kg bw/day

Dose / conc.:

1 000 mg/kg bw/day

No. of animals per sex per dose:

25

Control animals:

yes, concurrent vehicle

Maternal examinations:

Rats were observed daily and their weights were recorded every other day from Days 0 to 20 of pregnancy and on the day when the dosing commenced, i.e. Day 7 of pregnancy.

Ovaries and uterine content:

On the 20th day of gestation, rats were laparotomized under deep ether anesthesia and bled to death via aortotomy. The ovaries and uterus, with its contents, were then removed so that the numbers of corpora lutea in the former and those of implantations, live fetuses and resorption sites in the uterus could be counted. Dead fetuses were discriminated from embryonal deaths, the former being defined here as dead ones with apparent extremities and tail. Each fetus was weighed, sexed and examined to detect external morphological abnormalities. Weights of placentae were also recorded.

Fetal examinations:

After the observation for external morphological abnormalities, live fetuses were divided into two; half the number were subjected to examination of the skeleton and the rest to visceral examination. For the skeletal examination, fetuses were fixed in 90% alcohol and preparations made by a modification of the method of Jensh and Brent. Those for examination of the viscera were studied by the free-hand razor procedure of Wilson' after fixation in Bouin's solution.

Statistics:

The Student's t-test was employed in assessing the significance of any inter-group differences in mean values and the chi-square test to examine that of differences in frequency, with Yates' correction for cases of frequencies less than 6. In all these statistical analyses the 5 per cent level of significance was primarily adopted and evaluation at the 1 per cent level also recorded. All calculations, statistical processing and tabulation were carried out with an IBM 5100 computer system.

Clinical signs:

no effects observed

Description (incidence and severity):

In all groups including the control group, rat does became sedate immediately following administration and remained in that state for 3 - 4 hours. All appeared completely recovered from the manifestation when observed at the time of dosing on the next day.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

Decedents were encountered among the rats in all treated and control groups during the period of dosage. These deaths were due to faulty intragastric dosing and not from any toxicity of the vehicle or test compound.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

All groups displayed a tendency to transient depression of weight gain from Days 8 to 10 of pregnancy. The weight gains during the period of treatment and during the entire period of gestation were prone to be decreased in the 1,000 mg/kg group although there was no significant difference in this respect between any of the three treated groups and the control group.

Behaviour (functional findings):

not examined

Pre- and post-implantation loss:

no effects observed

Dead fetuses:

effects observed, treatment-related

Description (incidence and severity):

Doe Nos. 2510 and 2512 in the 1,000 mg/kg group were found at terminal examination to have totally or nearly all dead fetuses and therefore they were excluded from all subsequent programmed assessments.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Fetal body weight changes:

no effects observed

Description (incidence and severity):

No significant intergroup differences were observed between any treated group and the control group as to numbers of corpora lutea or implantations, number, sex ratio or weights of live fetuses, placental weights or fetal mortality.

Reduction in number of live offspring:

effects observed, treatment-related

Description (incidence and severity):

There were a total of 27 dead fetuses in two does (Nos. 3510 and 3512).

Changes in sex ratio:

no effects observed

Description (incidence and severity):

No significant intergroup differences were observed between any treated group and the control group as to numbers of corpora lutea or implantations, number, sex ratio or weights of live fetuses, placental weights or fetal mortality.

Changes in litter size and weights:

no effects observed

Description (incidence and severity):

No significant intergroup differences were observed between any treated group and the control group as to numbers of corpora lutea or implantations, number, sex ratio or weights of live fetuses, placental weights or fetal mortality.

External malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Externally deformed fetuses were found in the control group alone, but none in any of the treated group. These were a fetus with left facial hydrops from Doe (No. 506) and one with exencephaly, opened eyelids and spina bifida from Doe (No. 515).

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

On the results of skeletal examination of fetuses, it was only in the control group that skeletal abnormalities were noted, viz. missing os. parietale and other cranial bones in the abovementioned fetus from Doe (No. 515) and abnormal positions of costal connection to vertebrae in a fetus from Doe (No. 519).
No fetus with skeletal abnormalities was found at all in any of the treated groups.
There was no appreciable trend to retardation of skeletal ossification in any treated group as compared to the control group when assessed in respect of degree of ossification by reference to numbers of stained ribs, sternebrae, coccygeal vertebrae, metacarpal bones and metatarsal bones.
The fetuses from three dams (Nos. 511> 514 and 518) were precluded from the examination since their skeletons became dismembered through the process of stained preparations and thus they were inadequate for observation.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Visceral abnormalities observed in the present series were dilatation of renal pelvis and microphthalmia. Renal pelvis dilatation was seen in fetuses from both control and treated groups, with no significant difference in its incidence between any treated group and the control group. There were two fetuses with microphthalmus among the offspring from does given 200 mg/kg while no visceral abnormality of this form was seen in the 1,000 mg/kg group.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Abnormalities:

no effects observed

Key result

Developmental effects observed:

no

Conclusions:

There was no clear evidence of maternal or developmental toxicity in this study. Consequently, maternal and developmental NOAELs of 1000 mg/kg bw/d can be determined.

Executive summary:

1. Experiments were performed to assess the teratogenicity of Pencycuron in groups of rats given a suspension of the compound intragastrieally in doses of 0, 40, 200 or 1,000 mg/kg daily from the 7th to 14th days of pregnancy.
2. Sedation was evident as a sign of acute toxicologic reaction in rats of the control and all treated groups. The manifestation persisted for 3 ~ 4 hours immediately following administration. All cases showed a complete recovery by the time of dosing on next day.
3. Deaths occurred during the 8-day treatment period in all groups including the control group. These were due to faults with the procedure.
4. Maternal weight gain was prone to be depressed in all treated and control groups during the period from Day 8 to Day 10 of gestation. The weight gain during treatment and that throughout gestation tended to be reduced, though no statistical significance was seen, in the 1000 mg/kg group.
5. In respect of mean numbers of corpora lutea, implantations, dead fetuses (including resorption sites) or live fetuses, sex ratio, mean fetal weight or placental weight, there was no significant difference between any treated group and the control group.
6. External morphological abnormalities were noted in 2 fetuses from the control group, viz. exencephalia and hydrops.
7. Skeletal abnormalities were found in only 2 fetuses from the control group, namely, absence of some of the cranial bones and abnormal positions of costal connection to vertebrae. The examination showed no evidence of delayed skeletal ossification in any of the treated groups receiving up to 1,000 mg/kg or in the control group.
8. Visceral examinations of fetuses revealed dilatation of the renal pelvis in all treated and control groups, with no statistically significant intergroup difference in incidence. Two fetuses with microphthalmia were seen in the 200 mg/kg.
9. The present data show that NTH 19701 is neither embryolethal, fetolethal, nor teratogenic.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Quality of whole database:

The developmental toxicity of pencycuron has been investigated in GLP- and guideline-compliant studies in two species (rat and rabbit). 

Justification for classification or non-classification

The two two-generation reproductive toxicity studies with pencycuron do not indicate any effects on fertility or reproductive capacity.  Consequently, no classification for reproductive toxicity (effects on fertility) in any category is required under CLP.

The two pre-natal developmental toxicity studies with pencycuron do not indicate any effects on fetal development.  Consequently, no classification for reproductive toxicity (pre-natal developmental toxicity) in any category is required under CLP.

There are no data indicating an effect of pencycuron on or via lactation. Consequently, no classification for lactation effects is required under CLP.