Extended one-generation reproductive toxicity study of food-grade titanium dioxide E171 with emphasis on reproductive and endocrine endpoints

Abstract

Food-grade titanium dioxide E171 was administered in feed to Sprague Dawley rats in an extended one-generation reproductive toxicity (EOGRT) study (OECD Test 443). The dosed diet (0, 100, 300, or 1000 mg/kg body weight/day) started 10 weeks before mating and continued throughout the study. After weaning, pups were allocated to Cohorts 1 A/1B (to assess reproductive toxicity), 2 A/2B (to assess developmental neurotoxicity), and 3 (to assess developmental immunotoxicity); in addition, Cohort 1B was mated to produce an F2 generation and satellite F0 animals were evaluated for colonic aberrant crypt foci (ACF). In F0 animals, there were no systemic toxicity or reproductive effects, no treatment-related histopathological changes, and no ACF in the colon. Serum estradiol or testosterone concentrations were not changed in F0 or F1 animals. No pre-/postnatal developmental changes related to treatment were noted in F1 animals, and the reproductive performance of F1 Cohort 1B animals was unaffected. F2 pups showed no abnormalities in pre- or postnatal development (postnatal days 4–8). No treatment-related developmental neurotoxicity was observed in Cohorts 2 A/2B. Although no treatment-related immunotoxicity was observed in Cohort 3, the positive control did not induce the expected response; this segment of the study will be repeated. Analyses of blood and urine showed negligible systemic absorption of E171 from the gastrointestinal tract upon dietary ingestion. The no observed adverse effect level (NOAEL) for parental systemic toxicity, reproductive toxicity, offspring toxicity, and developmental neurotoxicity was considered 1000 mg/kg body weight/day. For developmental immunotoxicity, a NOAEL was not determined owing to insufficient T-cell-dependent antibody response in the positive control. Our study provides robust data on the reproductive toxicity and preneoplastic potential of E171.