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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:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Justification for type of information:
Data is from publication

Data source

Reference
Reference Type:
publication
Title:
Early Life Triclocarban Exposure During Lactation Affects Neonate Rat Survival
Author:
Rebekah C. M. Kennedy, Fu-Min Menn, Laura Healy, Kellie A. Fecteau, Pan Hu, Jiyoung Bae, Nancy A. Gee, Bill L. Lasley, Ling Zhao, and Jiangang Chen
Year:
2015
Bibliographic source:
Reproductive Sciences 2015, Vol. 22(1) 75-89

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
a cross-fostering design was implemented
Principles of method if other than guideline:
The objective of the present study was to identify the susceptive windows of gestational and postnatal test chemical exposure to offspring survival
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Triclocarban (3,4,4-trichlorocarbanilide; TCC)
- Molecular formula (if other than submission substance): C13H9Cl3N2O
- Molecular weight (if other than submission substance): b315.5861g/mol
- Substance type: Organic
- Physical state: No data
- Impurities (identity and concentrations): Purity 99% and impurities 1% (Unknown)

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
- Source: Harlan Laboratory, Dublin, Virginia
- Age at study initiation: (P) x wks; (F1) x wks (Animals were pregnant)
- Weight at study initiation: No data
- Fasting period before study: No data
- Housing: housed individually with Harlan Teklad laboratory grade 7087 soft cob bedding (Harlan Laboratories, Madison, Wisconsin) in clear plastic cages

- Use of restrainers for preventing ingestion (if dermal): yes/no
- Diet (e.g. ad libitum):
- Water (e.g. ad libitum): Ad libitum assess to water
- Acclimation period: Harlan ground 2020X chow

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20_C to 22 0C
- Humidity (%):of 40% to 50%.
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12:12-hour photoperiod

Administration / exposure

Route of administration:
oral: feed
Type of inhalation exposure (if applicable):
not specified
Vehicle:
other: feed
Remarks on MMAD:
No data available
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The test chemical supplement was prepared by first weighing the correct amount of test chemical and mixing the compound with small amounts of powdered chow using a mortar and pestle.

DIET PREPARATION
- Rate of preparation of diet (frequency): weekly
- Mixing appropriate amounts with (Type of food): powdered chow to obtain the required concentration.
- Storage temperature of food: no data
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
No data available
Details on mating procedure:
No mating were performed
Duration of treatment / exposure:
from GD 5 to on weaning/PND 21
Frequency of treatment:
Daily
Duration of test:
No data available
Doses / concentrations
Remarks:
Control=0%(0mg/kg)
0.2%=(200mg/kg)
0.5%=(500mg/kg)
No. of animals per sex per dose:
Control=5 females
0.2% (200mg/kg)= 5females
0.5% (500mg/kg)= 5females
Control animals:
yes, plain diet
Details on study design:
Dams were then fed with rat chow or chow supplemented with either 0.2% (200mg/kg) or 0.5%(500mg/kg) w/w test chemical. On PND 0, female pups were weighed and sexed based on anogenital distance (AGD). Litter size was culled to 6 females by random removal of pups on PND 0 right after sexing. After culling, on PND 0, a cross-fostering design was implemented within each litter. Briefly, each dam carried and nursed 2 female pups from their own original litter and fostered 2 female pups from each of the 2 other treatment groups. In this manner, each control dam raised 2 of their own pups, 2 pups born to 0.2% w/w-treated dams and 2 pups born to 0.5% w/w-treated dams. Each 0.2% w/w-treated dam raised 2 of their own pups, 2 pups born to 0.5%w/w-treated dams, and 2 pups born
to control dams. Finally, each 0.5% w/w-treated dam raised 2 of their own pups, 2 pups born to control dams, and 2 pups born to 0.2%w/w-treated dams. The treatment regimen continued from GD5 throughout lactation until the dams were sacrificed either on weaning/PND 21 or on the same date when all pups died.

Examinations

Maternal examinations:
Body weight and average RER were measured.
Ovaries and uterine content:
No data available
Fetal examinations:
Body weight difference in female pups born before and after the crossover manipulation were recorded on PND 0,3,6,9 and 21.
Pup mortality was determined throughout the study. The average RER measured on PND 41 in offspring. Vaginal opening and estrous cyclicity assessed with AGD measurement.
Statistics:
Data were presented as group mean + standard error of the mean. Data were analyzed using SPSS (version 20, IBM, Armonk, New York) by analysis of variance (ANOVA; ie, organ weights, body weight, AGD, test chemical) or ANOVA with repeat measurements (ie, changes of AGD and body weight over time). In addition, data were analyzed with a covariate of PND 21 body weight (offspring) or pretreatment body weight (dams) when appropriate. Mortality measurements were analyzed by Kaplan-Meier survival analysis with JMP Pro 10 (SAS Institute Inc, Cary, North Carolina), followed by pairwise Student-Newman- Keuls post hoc test when appropriate. Statistical significance was considered P <.05. Data were transformed if either normality or the equal variance assumption was invalid. If transformation did not correct normality or equal variance assumption, Kruskal-Wallis one-way ANOVA on ranks was used.
Indices:
No data available
Historical control data:
No data available

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
not specified
Dermal irritation (if dermal study):
not specified
Mortality:
not specified
Body weight and weight changes:
not specified
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not specified
Haematological findings:
not specified
Clinical biochemistry findings:
not specified
Urinalysis findings:
not specified
Behaviour (functional findings):
not specified
Immunological findings:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
not specified
Neuropathological findings:
not specified
Histopathological findings: non-neoplastic:
not specified
Histopathological findings: neoplastic:
not specified
Other effects:
no effects observed
Description (incidence and severity):
There was no significant difference in RER (Respiration excahnge ratio) in maternal animals at dose level 200 and 500mg/kg/day compared to control animals
Details on results:
No data available

Maternal developmental toxicity

Number of abortions:
not specified
Pre- and post-implantation loss:
not specified
Total litter losses by resorption:
not specified
Early or late resorptions:
not specified
Dead fetuses:
not specified
Changes in pregnancy duration:
not specified
Changes in number of pregnant:
not specified
Other effects:
no effects observed
Description (incidence and severity):
At birth, no statistical difference in number of live births or average birth weight per litter between groups was noted

Effect levels (maternal animals)

Key result
Dose descriptor:
NOAEL
Effect level:
500 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: RER and number of live births or average birth weight per litter
Remarks on result:
other: Not Specified

Maternal abnormalities

Abnormalities:
not specified

Results (fetuses)

Fetal body weight changes:
effects observed, non-treatment-related
Description (incidence and severity):
There was no initial statistical body weight difference in female pups born to control dams or pupsborn to either groups of 200 and 500mg/kg of treated dams prior to culling on PND 0. Average body weight was significantly less in pups nursed by test chemical supplemented dams at PND 3 with an average 16% decrease found in pups raised by 0.2% w/w test chemical-treated dams and a 25% decrease observed among pups raised by 0.5% w/w test chemical-treated dams compared to control raised pups.

Within each dam treatment group, however, no statistical body weight difference was observed among the pups with different in utero exposure status (ie, born to a 0.5% w/w test-treated dam, 0.2% w/w test-treated dam, or a control dam) at PNDs 3, 6, and 9, respectively.
Reduction in number of live offspring:
effects observed, treatment-related
Description (incidence and severity):
A significant reduction in pup number over time was observed between pups raised by 0.5% w/w or 0.2% w/w treated dams compared to those raised by controls.
Changes in sex ratio:
not specified
Changes in litter size and weights:
not specified
Changes in postnatal survival:
effects observed, treatment-related
Description (incidence and severity):
No pups raised by 0.5% w/w test chemical-treated dams survived beyond PND 5 compared to all pups raised by control dams survived throughout the study period
External malformations:
not specified
Skeletal malformations:
not specified
Visceral malformations:
not specified
Other effects:
not specified
Description (incidence and severity):
The abdomens of all pups exposed to test chemical were distended and all pups had diarrhea. Gross pathological examination of randomly selected pups (n =3) raised by the 0.5% w/w dams on PNDs 4 and 5 showed small acute gastric ulcers and fatty vacuolation of hepatocytes.

No statistical difference in AGD indexed by cube root of body weight (at the time AGD was acquired) was detected on PND 3 among offspring raised by different dam treatment groups.

The average RER measured on PND 41 from the 4 surviving offspring raised by 0.2% w/w dams was similar compared to the RER measured from offspring raised by control dams

Vaginal opening(VO): The average age of VO in the 4 surviving offspring raised by 0.2% w/w test chemical-treated dams was 38.5 days, while the aver
age age of VO from offspring raised by the control dams was 37.17 days. No significant difference were seen

Organ weight: no significant difference noted between any groups (200 and 500mg/kg) for any organ analyzed.

Estrus cycle assessment: No significant differece were observed in first date of estrus in test chemical treated groups and control group.
Details on embryotoxic / teratogenic effects:
No data available

Effect levels (fetuses)

Key result
Dose descriptor:
LOAEL
Effect level:
200 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
reduction in number of live offspring
changes in postnatal survival
other: The abdomens of all pups were distended and all pups had diarrhea, small acute gastric ulcers and fatty vacuolation of hepatocytes.
Remarks on result:
other: Not Specified

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified
Treatment related:
not specified

Applicant's summary and conclusion

Conclusions:
From the observations and results, the LOAEL for the maternal animals and NOAEL for the fetuses considered to be 500mg/kg and 200mg/kg respectively when test chemical exposed to Sprague Dawley rats during gestational and lactation period
Executive summary:

The objective of the present study was to identify the susceptive windows of gestational and postnatal test chemical exposure to offspring survival. In the present study, Dams were then fed with rat chow or chow supplemented with either 0.2% (200mg/kg) or 0.5%(500mg/kg) w/w test chemical. On PND 0, female pups were weighed and sexed based on anogenital distance (AGD). Litter size was culled to 6 females by random removal of pups on PND 0 right after sexing. After culling, on PND 0, a cross-fostering design was implemented within each litter. Briefly, each dam carried and nursed 2 female pups from their own original litter and fostered 2 female pups from each of the 2 other treatment groups. In this manner, each control dam raised 2 of their own pups, 2 pups born to 0.2% w/w-treated dams and 2 pups born to 0.5% w/w-treated dams. Each 0.2% w/w-treated dam raised 2 of their own pups, 2 pups born to 0.5%w/w-treated dams, and 2 pups born to control dams. Finally, each 0.5% w/w-treated dam raised 2 of their own pups, 2 pups born to control dams, and 2 pups born to 0.2%w/w-treated dams. The treatment regimen continued from GD5 throughout lactation until the dams were sacrificed either on weaning/PND 21 or on the same date when all pups died. The RER(respiration excahnge ratio) in maternal animal were determined. On PND 0, female pups were weighed and sexed based on anogenital distance (AGD) and a cross-fostering design was implemented within each litter. Pup mortality and change in body weight were monitored daily throughout the experiment. The Vaginal opening and estrous cyclicity assessment were performed. RER were determined. Gross pathological examination in 0.5%w/w treated group animals were performed and organ weights were also recorded.

The results of the study revealed, no significant difference in RER in maternal animals at dose level 200 and 500mg/kg/day compared to control animals. At birth, no statistical difference in number of live births or average birth weight per litter between groups was noted. There was no initial statistical body weight difference in female pups born to control dams or pupsborn to either groups of 200 and 500mg/kg of treated dams prior to culling on PND 0. Average body weight was significantly less in pups nursed by test chemical supplemented dams at PND 3 with an average 16% decrease found in pups raised by 0.2% w/w test chemical-treated dams and a 25% decrease observed among pups raised by 0.5% w/w test chemical-treated dams compared to control raised pups. Within each dam treatment group, however, no statistical body weight difference was observed among the pups with different in utero exposure status (ie, born to a 0.5% w/w test-treated dam, 0.2% w/w test-treated dam, or a control dam) at PNDs 3, 6, and 9, respectively.

A significant reduction in pup number over time was observed between pups raised by 0.5% w/w or 0.2% w/w treated dams compared to those raised by controls. No pups raised by 0.5% w/w test chemical-treated dams survived beyond PND 5 compared to all pups raised by control dams survived throughout the study period. The abdomens of all pups exposed to test chemical were distended and all pups had diarrhea. Gross pathological examination of randomly selected pups (n =3) raised by the 0.5% w/w dams on PNDs 4 and 5 showed small acute gastric ulcers and fatty vacuolation of hepatocytes. No statistical difference in AGD indexed by cube root of body weight (at the time AGD was acquired) was detected on PND 3 among offspring raised by different dam treatment groups. The average RER measured on PND 41 from the 4 surviving offspring raised by 0.2% w/w dams was similar compared to the RER measured from offspring raised by control dams. The average age of VO in the 4 surviving offspring raised by 0.2% w/w test chemical-treated dams was 38.5 days, while the average age of VO from offspring raised by the control dams was 37.17 days. No significant difference were seen in vaginal opening.  No significant difference in organ weight noted between any groups (200 and 500mg/kg) for any organ analyzed. No significant differece were observed in first date of estrus in test chemical treated groups and control group. From the observations and results, the NOAEL for the maternal animals and  LOAEL for the fetuses considered to be 500mg/kg and 200mg/kg respectively when test chemical exposed to Sprague Dawley rats during gestational and lactation period.