Phosphorous ester

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Additional information

Reproduction/Developmental Toxicity Screening Test

The subject of this study was the Reproduction/Developmental Toxicity Screening Test with the test item GARDO TP10451 in the Rat according to OECD 421 and the draft OECD guidance document 43. The guideline is designed for use with the rat, which is the preferred rodent species for reproduction toxicity testing. The purpose of this study was to obtain initial information on the possible effects of the test item on reproduction and development when administered orally (by gavage) to CRL:(WI)BR rats at repeated doses of 50, 250, and 1000 mg/kg body weight/day (mg/kg bw/day) compared to control animals. As a screening test, it was intended to provide initial information on possible effects on male and female reproductive performance such as gonadal function, mating behaviour, conception, pregnancy, parturition as well as on development of the F1 offspring from conception to day 4 post-partum associated with administration of repeated doses. The dose setting was based on findings obtained in previous studies (previous rodent study: repeated dose range finding study with the test item in rats LAB study code 08/625-100PE), and in agreement with the Sponsor. Doses were selected with the aim of inducing toxic effects but no death or suffering at the highest dose and a NOAEL at the lowest dose.

Stability and homogeneity of test item in the vehicle, PEG400, was analytically proven. Assessment of test item stability in this vehicle, in the conditions employed on the study indicated an up to 6 hr stability at room temperature, and 96 hr stability at 2-8°C, at concentrations from approximately 1 to 250 mg/mL in PEG400 formulations, with a recovery within the acceptable range of 100 ± 10% (104-94%). A separate analytical report provides this information. Analysis of dose formulation concentration and homogeneity was conducted during the study from all the concentrations employed; the formulations were homogenous, and the measured concentrations ranged from 102 to 109 % of nominal concentrations. The analytical results were considered suitable for the study purposes.

Animals were inspected for signs of morbidity and mortality twice daily (at the beginning and end of each day). Clinical observations for signs of ill health or reaction to treatment were made at least once daily, with detailed examination performed weekly. Special attention was paid to evaluation of the mating, pregnancy, parturition and post-partal periods, and relevant parameters and/or indices were measured and/or calculated. Body weight and food consumption were measured at least weekly. Gross necropsy was conducted at the end of the treatment period. The absolute and relative organ weights of selected organs and tissues were determined. A histopathological examination was performed on the selected preserved organs and tissues of the animals of the control and high dose groups, on the testes and epididymides of the low and mid dose males, and on abnormal tissues from low and mid dose groups.

Results and Conclusion

GARDO TP10451 administered daily by oral gavage in Wistar rats, for 28 days in the male animals, and up to 47 days (females), at dose levels of 50, 250 and 1000 mg/kg bw/day, did not result in any clinical changes that could be ascribed to the treatment.

No effects considered adverse, or toxicologically significant, were noted on the mean body weight, body weight gain, or food consumption values in the treated groups compared to control animals. Treatment related effects were observed in the body weight gain of females in the high dose group. These effects were nevertheless not regarded as adverse, taking into account the absence of other treatment related effects at this dose level.

There were no significant differences between the control and test item treated groups with regard to reproductive ability, or in the mating, fertility or gestation indices. Test item administration did not impact the duration of the mating period. Successful coitus (sperm positive vaginal smears and/or vaginal plugs) generally occurred within up to 8 days of pairing (cohabitation). No test item effect on the duration of pregnancy was observed. All females littered in 22 to 23 days. There were no abnormalities in pups that were ascribed to the treatment. All the parturitions were normal. There were no adverse effects, or biologically significant variations of the parameters related to pregnancy, parturition, or post-partal period noted in the treated groups at dose levels up to and including 1000 mg/kg bw/day compared to control animals. There were no test item-related alterations in the delivery data of GARDO TP10451 treated dams as compared to the control value. The number of corpora lutea and implantations were comparable or slightly higher in the treated groups up to and including 1000 mg/kg bw/day, compared to females in the control groups. Pre-implantation, intrauterine and total mortality values were lower in the high dose group administered 1000 mg/kg bw/day than in the control animals. Slightly higher values than control without attaining statistical significance were observed at 50 and 250 mg/kg bw/day; however, the differences were minor, and based on the lack of similar changes in the high dose group, these variations were neither considered toxicologically significant, nor related to test item administration.

Litter examination did not reveal any clinical, or macroscopic test item-related effects compared to observations noted in the control group. GARDO TP10451 administration had no adverse effect on the mean or total number of pups, or pup survival index. The sex ratio was similar in the control and treated groups, and no significant variations were observed on PN4 vs. PN0.

In the parent animals surviving to scheduled termination, the administration of GARDO TP10451 at dose levels of 50, 250 or 1000 mg/kg bw/day was not associated with any adverse test item-related macroscopic or microscopic findings. There were no treatment-related organ weight changes. Treatment related effects were observed in apoptosis parameters in the epididymides in males in the high dose group. These effects were nevertheless not regarded as adverse in the absence of an impairment of any reproductive performance parameters in the high dose group.

In conclusion, under the conditions of this study, a no observed effect level (NOEL) for parental effects (systemic) of 250 mg/kg bw/day was derived for GARDO TP10451 based on female body weight reductions and apoptosis in the epididymides of males in the high dose group. The no observed adverse effect level (NOAEL) for GARDO TP10451 for parental effects (systemic) was 1000 mg/kg bw/day based on the absence of toxicologically adverse effects up to and including the high dose level of both sexes. For reproduction parameters, no effects were noted at any dose level, resulting in a NOAEL of 1000 mg/kg bw/day. For pup growth rate and adverse effects, the NOAEL was 1000 mg/kg bw/day.

Short description of key information:
Under the conditions of a reproduction/developmental toxicity screening test (OECD 421), a no observed effect level (NOEL) for parental effects (systemic) of 250 mg/kg bw/day was derived for GARDO TP10451 based on female body weight reductions and apoptosis in the epididymides of males in the high dose group. The no observed adverse effect level (NOAEL) for GARDO TP10451 for parental effects (systemic) was 1000 mg/kg bw/day based on the absence of toxicologically adverse effects up to and including the high dose level of both sexes. For reproduction parameters, no effects were noted at any dose level, resulting in a NOAEL of 1000 mg/kg bw/day. For pup growth rate and adverse effects, the NOAEL was 1000 mg/kg bw/day.

Justification for classification or non-classification

Based on the results of the reproduction/developmental toxicicty screening test (no adverse effects up to 1000 mg/kg bw/day) GARDO TP10451 has not to be classified regarding reproduction/developmental toxicity according to CLP (GHS) and 67/548/EEC.