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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
Study period:
2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study was conducted in compliance with the OECD (1998) and EPA TSCA (1989) Good Laboratory Practices Guidance. (Author)
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report Date:
2005

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: OECD 422
Deviations:
yes
Remarks:
See Principles of Method
Principles of method if other than guideline:
The study exceeded the OECD 422 guideline design by extending dosing of F0 females through Day 21 of lactation (total of 8-9 weeks). The original study design included evaluation of 28 day exposure in females (to correlate with 28 day exposure in males), male and female recovery groups, and extended post weaning evaluation (70 days) in F1 offspring. The final study report contains all sections required by the OECD 422 guideline (1996), including data collected on the FO parental animals and on the Fl offspring to their weaning on pnd 21 (an extension beyond the specified termination on pnd 4 in the OECD 422 [1996] testing guideline). The data collected on the 28-day females, the recovery males and females, and on the F1 offspring animals after weaning were collected as initially specified in the protocol but were not included in the study report. The data not reported (and wet tissues, blocks and slides not processed or examined) were retained in the study records and archived with the study upon the submission of the final report.
GLP compliance:
yes
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
other: liquid
Details on test material:
- Name of test material (as cited in study report): TDP- Analytical purity: > 99%- Lot/batch No.: Doverphos 6, Batch 162T041801

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
TEST ANIMALS - Source: Charles River Breeding Laboratories, Raleigh, NC - Age at study initiation: 10 weeks - Housing: The animals were individually housed upon arrival, during the acclimation period, and upon the initiation of the treatment period in solid-bottom polycarbonate cages with stainless-steel wire lids (Laboratory Products, Rochelle Park, NJ) with Sani-Chip® cage litter (P.J. Murphy Forest Products Corp., Montville, NJ). Study animals were housed 2 per cage (1 male: 1 female from the same dose group) during the mating period. Females were caged individually once they were successfully mated (or at the end of the mating period) and throughout gestation. Females were housed with their litters throughout the lactation period. Randomly selected Fl weanlings (10/sex/group), males, and females were singly housed during the postweaning exposure period. - Diet (e.g. ad libitum): Pelleted Purina Certified Rodent Diet® (No. 5002, PMI Feeds, Inc., St. Louis, MO was available ad libitum. - Water (e.g. ad libitum): Tap water (source: City of Durham, Department of Water Resources, Durham, NC) was available ad libitum in plastic water bottles with butyl rubber stoppers and stainless-steel sipper tubes. - Acclimation period: 1 week ENVIRONMENTAL CONDITIONS - Temperature (°C): 71.1 to 76.2°F - Humidity (%): 37.2% to 69.6%. - Photoperiod (hrs dark / hrs light): 12-hour light cycle per day

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Remarks:
Mazola® corn oil
Details on exposure:
Male and female CD (Sprague-Dawley(SD)) F0 rats were administered TDP orally by gavage at 0, 50, 250 and 1000 mg/kg/day at a dose volume of 5 ml/kg/day in Mazola® corn oil, 10 animals/sex/dose, for 2 weeks of prebreed exposure (males and females), 2 weeks of mating (males and females) and 3 weeks of gestation and lactation each (F0 females).
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Homogeneity and stability studies were run on TDP in corn oil at concentrations of 10, 50, and 200 mg/mL (TDP in corn oil). The 50 and 200 mg/mL concentrations were prepared weekly as they were found to be stable. The 10 mg/mL concentration was prepared daily due to stability concerns. Dosage formulations analyzed during the study were found to be 90.8-110% of nominal concentrations.
Details on mating procedure:
After the 2-week prebreed exposure period, animals were randomly mated within treatment groups for a 2-week mating period to produce the F1 generation, with continuing exposure. - Impregnation procedure: cohoused- If cohoused: - M/F ratio per cage: 1:1 - Length of cohabitation: 14 days- Proof of pregnancy: vaginal plug / sperm in vaginal smear referred to as day 0 of pregnancy.- Once vaginal sperm were observed, the male and female from that mating pair were individually housed.Any female that did not show evidence of successful mating after 14 days of cohabitation continued on the original weekly weighing schedule and was monitored for evidence of pregnancy and littering.
Duration of treatment / exposure:
8 weeks. 2 weeks of prebreed exposure (males and females), 2 weeks of mating (males and females), and 3 weeks of gestation and lactation each (FO females).
Frequency of treatment:
Once a day/7days per week
Duration of test:
F0 males - 28 days F0 females - 8-9 weeks (14 days prebreed, mating, gestation, lactation through pnd 21)
No. of animals per sex per dose:
10 animals/sex/dose
Control animals:
yes

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes - Cage side observations: changes in skin and fur, eyes, mucous membranes, respiratory and circulatory systems, autonomic and central nervous systems, somatomotor activity, and behavior pattern. Beginning on gd 20, each female was observed twice daily (a.m. and p.m.) for evidence of littering.DETAILED CLINICAL OBSERVATIONS: Yes - Time schedule: WeeklyBODY WEIGHT: Yes- Time schedule for examinations: F0 males and females were recorded weekly during the prebreed period for both sexes and for F0 females during gestation and lactation. During gestation, F0 females were weighed on gestational days (gd) 0, 7, 14, and 20. Dams producing litters were weighed on pnd 0, 4, 7, 14, and 21.FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): - F0 males and females were recorded weekly during the prebreed period for both sexes and for F0 females during gestation and lactation. During pregnancy of F0 females, feed consumption was recorded for gd 0-7, 7-14, and 14-20. During lactation of Fl litters, maternal feed consumption was measured for pnd 0-4, 4-7, 7-14, and 14-21, although maternal feed consumption after pnd 14 was confounded by the contribution from the pups, since pups are self-feeding by this time. Feed consumption was not measured during the period of cohabitation, since 2 adult animals (1 male and 1 female) were in the same cage. POST-MORTEM EXAMINATIONS: Yes - All FO parental animals, were subjected to a complete gross necropsy, with selected organs weighed and retained or discarded as appropriate (see Table 2). The gross necropsy included examination of the external surfaces, all orifices, the carcass, the thoracic, abdominal, and pelvic cavities and their viscera, and cervical tissues and organs. Gross lesions were recorded and retained in 10% neutral buffered formalin, with selected organs weighed and retained. Uteri of FO females were examined for the number of nidation (implantation) scars.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination on lactation Day 21: YesExaminations included:- Gravid uterus weight: No data- Number of corpora lutea: No data- Number of implantations: Yes - Number of early resorptions: No data- Number of late resorptions: No data- Other
Fetal examinations:
On the day of birth (postnatal day [pnd] 0), anogenital distance was measured and body weights recorded for all live F1 pups in all litters. F1 litters were culled on pnd 4 to yield as nearly as possible 5 males and 5 females per litter. The culled F1 pups were weighed, euthanized, and necropsied with complete external and visceral examinations. For the remaining F1 pups, survival indices were calculated at least weekly through weaning (pnd 21).- Body Weight: All F1 pups were individually counted, sexed, weighed, and examined grossly at birth (pnd 0), at pnd 4,7, and 14, and at weaning (pnd 21).- External examinations: Yes: all per litter- Other: All retained F1 weanlings were weighed and feed consumption measured once per week until their scheduled demise. Daily F1mortality and clinical. observations were conducted as described for the F0 animals. All nonselected FI weanlings were subjected to a complete gross necropsy (external and visceral) examination, with gross lesions retained in IO% neutral buffered formalin.
Statistics:
The unit of comparison was the male, female, pregnant female, or the litter, as appropriate. Treatment groups were compared to the concurrent control group using either parametric ANOVA under the standard assumptions or robust regression method, which do not assume homogeneity of variance or normality. The homogeneity of variance assumption was examined via Levene's Test. If (p<0.05), robust regression methods were used to test all treatment effects, which use variance estimators that make no assumptions regarding homogeneity of variance or normality of the data. If Levene's Test did not reject the hypothesis of homogeneous variances, standard ANOVA techniques were applied for comparing the treatment groups. The GLM procedure in SAS® Release 8 was used to evaluate the overall effect of treatment and, when a significant treatment effect was present, to compare each exposed group to the control via Dunnett's Test. A one-tailed test (i.e., Dunnett's Test) was used for all pairwise comparisons to the vehicle control group, except that a two-tailed test was used for parental and pup body weight and organ weight parameters, feed consumption, percent males per litter, and anogenital distance. Student's t-test was used for analysis ofbody weight and organ weights from the recovery males and females and the 28-day females. All indices were analyzed by Chi-Square Test for Independence. When Chi-Square revealed significant (p<0.05) differences among groups, then a Fisher's Exact Probability Test, with adjustments for multiple comparisons, w':!s used for pairwise comparisons between each treatment group value and the control group value. Acquisition of developmental landmarks as well as anogenital distance, was also analyzed by Analysis of Covariance. For correlated data SUDAAN® software (RTI, 2001) was used for analysis of overall significance and pairwise comparisons to the control group values.
Indices:
Gestation length.Number of total implantation sites per litter and number of total and live pups per litter at birth.Percent postimplantation loss per litter.Live birth and stillbirth indices.Sex ratio per litter.Survival indices were calculated on pnd 0, 4, 7, and 14 and at weaning.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
no effects observed

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effectsDetails on maternal toxic effects:TDP, administered by gavage once daily at 0, 50, 250, 1000 mg/kg/day to parental FO CD® (SD) rats, 10/sex/group, through prebreed, mating, gestation, and lactation, resulted in essentially no treatment- or dose-related adult FO parental toxicity at any dose at any time.

Effect levels (maternal animals)

Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
other: No effects
Remarks on result:
not determinable due to absence of adverse toxic effects

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effectsDetails on embryotoxic / teratogenic effects:There was no evidence of Fl offspring toxicity either at birth or during lactation. There were no effects on survival indices, litter size, sex ratio/litter, or pup deaths across any groups. Body weights of pups per litter (all pups or separately by sex) were equivalent across all groups for all time points, except for significant increases in female and all pup (but not male pup) body weights/litter at 50 mg/kg/day on pnd 0, most likely due to the slightly reduced live litter size (13.1) at this dose relative to the control live litter size (15.8). There were no effects on anogenital distance for either sex at birth. There was also no Fl treatment- or dose-related systemic or developmental toxicity at any dose at any time.

Effect levels (fetuses)

Key result
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No effect
Remarks on result:
not determinable due to absence of adverse toxic effects

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
TDP administered by gavage once daily at 0, 50, 250 and 1000 mg/kg/day to parental F0 CD (SD) rats, 10/sex/group through prebreed, mating, gestation and F1 lactation resulted in essentially no treatment or dose related adult F0 parental toxicity at any dose at any time. Reproductive toxicity was not present in F0 males or females. There was also no F1 offspring toxicity observed postnatally through the weanling necropsy. Therefore, the F0 male and female systemic no observable adverse effect level (NOAEL) was at or above 1000mg/kg/day for males and females. The NOAELs for F0 reproductive toxicity were observed at or above 1000 mg/kg/day for males and females. The NOAELs for F1 offspring toxicity during lactation were also at or above 1000 mg/kg/day for males and females. (Author)
Executive summary:

In a Guideline (modified OECD 422) GLP study with extended treatment to Day 21 of lactation, TDP administered by gavage once daily at 0, 50, 250, 1000 mg/kg/day to parental FO CD® (SD) rats, 10/sex/group, through prebreed, mating, gestation, and Fl lactation, resulted in essentially no treatment- or dose-related adult FO parental toxicity at any dose at any time. Reproductive toxicity was not present in FO males or females. There was also no Fl offspring toxicity observed postnatally through the weanling necropsy. Therefore, the FO male (28 days) and female (8 -9 weeks) systemic no observable adverse effect levell (NOAEL) was at or above 1000 mg/kg/day. The NOAELs for FO reproductive toxicity were at or above 1000 mg/kg/day for males and females. The NOAELs for Fl offspring toxicity during lactation were also at or above 1000 mg/kg/day for males and females.