Alkyltin compounds are used as stabilizers and antifouling agents. Food chain accumulation and bioconcentration have been demonstrated in crabs, oysters and salmon exposed to
tributyltin oxide. In mammalian species,
tributyltin compounds may be metabolized to
dibutyltin derivatives and related metabolites. Di- and tributyltins appear to be less potent neurotoxicants than trimethyltins and triethyltins. Dibutyltins and tributyltins produced bile duct damage in rats, mice and hamsters.
Tributyltin oxide and
dibutyltin and dioctyltin compounds are potent thymolytic and immunotoxic agents in rats.
Tributyltin oxide at 5 ppm in the rat diet produced immunotoxicity in a 2-year feeding study, and at 50 ppm increased the incidence of
tumors of endocrine origin. In preliminary reports, 5 ppm
tributyltin produced no detectable increase in
tumor incidence, and 0.5 ppm produced no detectable immunotoxicity in long-term studies.
Tributyltin oxide and
dibutyltin acetate did not appear to be mutagenic in a large battery of mutagenicity assays but produced base-pair substitutions in one of the bacterial strains tested.
Tributyltin oxide produced mutations in Chinese hamster ovary cells, increased the incidence of micronuclei in the erythrocytes of exposed male BALB/c mice, and was highly embryotoxic in vitro. Embryotoxic and teratogenic effects in mice exposed to
tributyltin oxide in vivo may have been due either to direct
tributyltin oxide action or responses secondary to maternal toxicity. More information is needed to determine the applicability to human risk assessments of the immunotoxicity data derived from rat studies and to establish a definitive tolerable daily intake for
tributyltin oxide.