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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Justification for type of information:
Data is from Ministry of Health, Labor and Welfare report

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Principles of method if other than guideline:
Developmental toxicity test of test chemical was carried out in Sprague-Dawley rats.
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
2-Naphthol
Cas Number:
135-19-3
Molecular formula:
C10H8O
IUPAC Name:
2-Naphthol
Test material form:
solid: flakes
Details on test material:
- Name of test material (as cited in study report):2-naphthol
- Molecular formula (if other than submission substance): C10H8O

- Molecular weight (if other than submission substance):144.172

- Substance type: Organic
- Physical state: Solid: grey flakes
- Impurities (identity and concentrations): purity: 99.6%, gray white flake containing 0.3% of test chemical as an impurity

Test animals

Species:
rat
Strain:
other: Sprague-Dawley strain (Crj: CD) rats
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Tsukuba breeding center, Charles River Japan Co., Ltd.
- Age at study initiation: No data available
- Weight at study initiation: No data available
- Fasting period before study: No data available
- Housing: housed in a metallic wire mesh floor cage in a breeding room
- Use of restrainers for preventing ingestion (if dermal): yes/no: No data available
- Diet (e.g. ad libitum): No data available
- Water (e.g. ad libitum): tap water, provided ad libitum
- Acclimation period: No data available

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24 ± 1 ° C
- Humidity (%): 50 to 65%
- Air changes (per hr): about 15 times / hour
- Photoperiod (hrs dark / hrs light): lighting for 12 hours

Administration / exposure

Route of administration:
oral: gavage
Type of inhalation exposure (if applicable):
not specified
Vehicle:
CMC (carboxymethyl cellulose)
Remarks on MMAD:
No data available
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: The dosing solution was prepared by mixing the test chemical in vehicle with a magnetic stirrer

DIET PREPARATION
- Rate of preparation of diet (frequency): No data available
- Mixing appropriate amounts with (Type of food): No data available
- Storage temperature of food: No data available

VEHICLE
- Justification for use and choice of vehicle (if other than water):No data available
- Concentration in vehicle: No data available
- Amount of vehicle (if gavage): 5ml/kg
- Lot/batch no. (if required): No data available
- Purity:No data available
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
No data available
Details on mating procedure:
Matings were conducted in males and females 1: 1 within the same group for a period of 3 weeks, and confirming the presence of sperm in the vaginal smear and confirming the vaginal plug every morning.
Duration of treatment / exposure:
10 weeks (71 days of administration)
Frequency of treatment:
Daily
Duration of test:
No data available
Doses / concentrations
Remarks:
0 (vehicle control)= 25male and 25female
10mg/kg=25male and 25female
40mg/kg=25male and 25female
160 mg/kg=25male and 25female
No. of animals per sex per dose:
0 (vehicle control)= 25male and 25female
10mg/kg=25male and 25female
40mg/kg=25male and 25female
160 mg/kg=25male and 25female
Control animals:
yes, concurrent vehicle
Details on study design:
Animals were orally administered from 10 weeks of age including mated up to 3 weeks. The males were necropsied after one week passed after the mating period. Females were allowed to spontaneously deliver after mating and necropsied with their babies on nursing 21th. Both males and females continued to be administered until the day before necropsy, during which the general condition of the parent animal, weight gain and changes in food intake were observed, and at the same time the reproductive ability, including delivery and lactation of the parent animal, and weaning of the infant was observed.

Examinations

Maternal examinations:
Parent animals were observed for mortality, general condition, change in weight, food intake, estrus cycle assessment. Animals were sacrificed to determined presence or absence of abnormalities of major organs thoracic abdomen, including the pituitary glands, stomach, testis, epididymis, coagulated glands, seminal vesicles, and prostate in males and pituitary, stomach, ovary, uterus, cervix and vagina in females
Ovaries and uterine content:
Estrus cycle were determined before 2 weeks of start of mating confirmation day, two weeks before the start of administration and two weeks after the start of the administration.
Fetal examinations:
Number of births, litter count and weight measurement. Offspings were sacrificed to determined presence or absence of abnormality on the external surface
Statistics:
Fisher's direct probability test 1) was carried out on frequency of type of sex cycle, mating rate, conception rate, morphological abnormality frequency of babiesAccording to histopathological examination findings, the Mann-Whitney U test 2)) shows the grade-separated data, and the total value of the positive grade is obtained by Fisher's direct probability one-sided test 3) between the control group and each test substance administration group Significant difference test was carried out. For the other data, we tested the uniformity of variance of each group by Bartlett method 4) , with the value obtained for each individual, or the average value for each litter as one sample . If the variance is uniform, a one-way analysis of variance 4) was performed, and when significance was observed between the groups, multiple comparisons were performed according to the Dunnett method 5) . On the other hand, Kruskal-Wallis 6) rank test is performed when the variance is 0 in any group and when the variance is not uniform, and if significance is observed between the groups.
Indices:
Conception rate was determined
Historical control data:
No data available

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
no effects observed
Description (incidence and severity):
Nasal discharge, eyelid ptosis or closed eyes, in group administered with 40 mg / kg or more but not in 160mg/kg group , lacrimation in 160 mg / kg administration group was transiently observed Salivation was observed in each administration group of the test substance.
Dermal irritation (if dermal study):
not specified
Mortality:
no mortality observed
Description (incidence):
In males, one patient in the 160 mg / kg dose group died on the 60th day of administration.
In females, there were no deaths or moribund
Body weight and weight changes:
no effects observed
Description (incidence and severity):
No significant difference between the control group and each test group administered group
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
In males no change in food consumption were observed, however in females no change in food consumption uring the period before mating, but significantly lower values than control group, after pregnancy and during the nursing stage
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
not specified
Clinical biochemistry findings:
not specified
Urinalysis findings:
not specified
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
Spontaneous locomotor reduction and salivation were observed transiently after administration and no abnormality was observed in both treated males and femlaes. There was a decrease in locomotor activity, eyelid ptosis or closed eyes, and nasal discharge in group administered with 40 mg / kg or more, lacrimation in 160 mg / kg administration group.
Immunological findings:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
no effects observed
Description (incidence and severity):
There was no change depending on the dose of the test substance in reproductive organsof male and females. Abnormality was not found in the reproductive organs of the 160 mg / kg administration group.
Neuropathological findings:
not specified
Histopathological findings: non-neoplastic:
effects observed, non-treatment-related
Description (incidence and severity):
No abnormality was observed in pituitary gland. In males, in each case in the 40 mg / kg and 160 mg / kg administration groups, the spermatogonia of the spermatogenic cells in the 14 th stage of the spermatogenesis cycle mild degeneration was observed, and cell debris was observed in the lumen of the epididymis in the example of 40 mg / kg administration group. Unilateral seminal vesicle atrophy was observed in each group including the control group. no avnormality were seenon seminal vesicle and Coagulated glands In females, no abnormality was observed in the pituitary gland, stomach, ovary, uterus, cervix and vagina.

Histopathological findings: neoplastic:
not specified
Other effects:
effects observed, treatment-related
Description (incidence and severity):
Hair loss was observed in all the treated animals

Maternal developmental toxicity

Number of abortions:
no effects observed
Pre- and post-implantation loss:
no effects observed
Description (incidence and severity):
Implantation number in treated animals was equivalent to control animals
Total litter losses by resorption:
effects observed, treatment-related
Description (incidence and severity):
The litter size was significantly low value in 160mg/kg/day group compared to control group.
Early or late resorptions:
not specified
Dead fetuses:
not specified
Changes in pregnancy duration:
no effects observed
Description (incidence and severity):
No change in pregnancy duration were seen in treated females.
Changes in number of pregnant:
not specified
Other effects:
no effects observed
Description (incidence and severity):
No abnormality in labor condition was observed, and there was no effect on birth rate

Effect levels (maternal animals)

Dose descriptor:
NOAEL
Effect level:
160 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
behaviour (functional findings)
body weight and weight gain
changes in pregnancy duration
clinical signs
effects on pregnancy duration
food consumption and compound intake
gross pathology
histopathology: non-neoplastic
maternal abnormalities
mortality
pre and post implantation loss
total litter losses by resorption
other: labor condition was normal no effect on birth rate

Results (fetuses)

Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
Body weight at the postnatal day 21 was slightly lower in the 160 mg / kg administration group
Reduction in number of live offspring:
effects observed, treatment-related
Description (incidence and severity):
Number of live pups examined reduced in highest dosed group
Changes in sex ratio:
no effects observed
Description (incidence and severity):
There was no effect of administration on sex ratio
Changes in litter size and weights:
effects observed, treatment-related
Description (incidence and severity):
The litter size after adjustment of litter size was decreased in 160mg/kg/day group
Changes in postnatal survival:
effects observed, treatment-related
Description (incidence and severity):
In 160mg/kg /day group the postnatal survival declines comapared to control
External malformations:
no effects observed
Description (incidence and severity):
No morphological changes including malformations where observed
Skeletal malformations:
no effects observed
Description (incidence and severity):
No morphological changes including malformations where observed
Visceral malformations:
no effects observed
Description (incidence and severity):
No morphological changes including malformations where observed
Other effects:
no effects observed
Description (incidence and severity):
No growth inhibition was observed in the administration group of 40 mg / kg or less

Effect levels (fetuses)

Key result
Dose descriptor:
NOAEL
Effect level:
40 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
changes in sex ratio
external malformations
skeletal malformations
visceral malformations
other: No growth inhibition

Overall developmental toxicity

Key result
Developmental effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
From the observation and results, the NOAEL for P0 generation and F1 generation was considered to be 160mg/kg/day and 40mg/kg/day respectively.
Executive summary:

In the present study, developmental toxicity test of test chemical was carried out and the developmental toxicity profile to male and female animals of test chemical was examined. In the study, animals were orally administered from 10 weeks of age including mated up to 3 weeks. The males were necropsied after one week passed after the mating period. Females were allowed to spontaneously deliver after mating and necropsied with their babies on nursing 21th. Both males and females continued to be administered until the day before necropsy, during which the general condition of the parent animal, weight gain and changes in food intake were observed, and at the same time the reproductive ability, including delivery and lactation of the parent animal, and weaning of the infant was observed. The results of the parenteral examination revealed that, no mortality in treated animals at 10, 40 and 160mg/kg/day for 10 weeks,including mating period, the clinical signs examination of animlas shows, nasal discharge, eyelid ptosis or closed eyes, in group administered with 40 mg / kg or more but not in 160mg/kg group , lacrimation in 160 mg / kg administration group was transiently observed. Salivation was observed in each administration group of the test substance.No test chemical related chnages on food consumption and body weight changes were observed. Spontaneous locomotor reduction and salivation were observed transiently after administration and no abnormality was observed in both treated males and femlaes.  There was a decrease in locomotor activity, eyelid ptosis or closed eyes, and nasal discharge in group administered with 40 mg / kg or more, lacrimation in 160 mg / kg administration group. There was no change depending on the dose of the test substance in reproductive organsof male and females. The histopathological study relealed no abnormality in pituitary gland. In males, in each case in the 40 mg / kg and 160 mg / kg administration groups, the spermatogonia of the spermatogenic cells in the 14 th stage of the spermatogenesis cycle mild degeneration was observed, and cell debris was observed in the lumen of the epididymis in the example of 40 mg / kg administration group.  Unilateral seminal vesicle atrophy was observed in each group including the control group. No abnormality were seen on seminal vesicle and Coagulated glands In females, no abnormality was observed in the pituitary gland, stomach, ovary, uterus, cervix and vagina. The maternal developmental toxicity includes, Implantation number in treated animals was equivalent to control animals. The litter size was significantly low value in 160mg/kg/day group compared to control group. No change in pregnancy duration were seen in treated females. No abnormality in labor condition was observed, and there was no effect on birth rate. The examination of pups revealed, body weight at the postnatal day 21 was slightly lower in the 160 mg / kg administration group. Number of live pups examined reduced in highest dosed group. There was no effect of administration on sex ratio. The litter size after adjustment of litter size was decreased in 160mg/kg/day group. In 160mg/kg /day group the postnatal survival declines comapared to control.No morphological changes including external, skeletal and visceral malformations where seen in treated animals. From the observation and results, the NOAEL for P0 generation and F1 generation was considered to be 160mg/kg/day and 40mg/kg/day respectively.