Dose range-finding prenatal developmental toxicity study
Groups of 11 time-mated female rats were administered 0, 300, 650, or 1,000 mg TCPP/kg body weight per day (mg/kg/day) in 0.5% aqueous methylcellulose by gavage from GD 6 to GD 20. Vehicle control (0 mg/kg) animals received aqueous methylcellulose.
Maternal toxicity was observed in the 1,000 mg/kg group as evidenced by 7 of 11 dams being either found dead or euthanized moribund. Associated clinical observations in the 1,000 mg/kg group included convulsion, tremors, prone, gasping, hypoactivity, hunched posture, nasal discharge, stained fur, piloerection, salivation, and rooting (pre- and postdosing), which occurred throughout gestation. One female in the 650 mg/kg group was euthanized moribund on GD 16 with associated clinical observations including cold to touch, hypoactivity, paleness, ataxia, and labored breathing, which may have been related to TCPP exposure. All vehicle control and 300 mg/kg animals survived to study termination. No TCPP-related effects were found on maternal body weights, body weight gain, or feed consumption from GD 6 to GD 20. Additionally, there were no significant exposure-related effects on postimplantation loss, fetal body weights, or fetal sex ratio, although limited litters were available for assessment in the 1,000 mg/kg TCPP group because of maternal toxicity. Finally, there were no significant exposure-related external fetal findings (including examination of the palate).
Prenatal developmental toxicity study
Because of the maternal toxicity observed at 1,000 mg/kg in the dose ranging-finding study, groups of 25 time-mated female rats were administered 0 (n = 50), 162.5, 325, or 650 mg TCPP/kg/ body weight per day in 0.5% aqueous methylcellulose by gavage from GD 6 to GD 20. Vehicle control (0 m/kg) animals received aqueous methylcellulose. Animals were added to the vehicle control group to obtain historical control data for both maternal and fetal findings in this strain of rat. In this study, TCPP was well tolerated and no exposure-related effects occurred on mortality, maternal body weights, body weight gains, or feed consumption during gestation. Low incidences of clinical observations including nasal discharge, salivation, twitches, ataxia, piloerection, audible respiratory sounds, and hyperactivity were observed in the 650 mg/kg group. Adverse clinical observations were not observed in other groups exposed to TCPP. There were no notable placental or other maternal gross observations at necropsy except for dose-related increases in absolute (9%, 16%, and 26% at 162.5, 325, and 650 mg/kg, respectively) and relative liver weights.
No significant effects of TCPP were observed on postimplantation loss, mean fetal body weights, or fetal sex ratio. Likewise, no biologically relevant exposure-related malformations were found in external, visceral, and skeletal fetal exams of groups exposed to TCPP.
Under the conditions of the prenatal study, no evidence of developmental toxicity of TCPP was found in Hsd:Sprague Dawley SD rats administered 162.5, 325, or 650 mg/kg in the absence of overt maternal toxicity.
National Toxicology Program (NTP). 2020. NTP developmental and reproductive toxicity technical report on the prenatal development studies of tris(chloropropyl) phosphate (CASRN 13674‑84-5) in Sprague Dawley (Hsd:Sprague Dawley SD) rats (gavage studies). Research Triangle Park, NC: National Toxicology Program. DART Report 01. https://doi.org/10.22427/NTP-DART-01