Organotin compounds: toxicokinetic aspects

Organotin compounds have a broad range of applications. While dialkyltin compounds are used primarily as stabilizers for plastics, trisubstituted organotins are mainly used as biocides e.g., as an active ingredient of marine antifouling paints for boats and ships. Since a number of organotin compounds have been demonstrated to be toxic, there is increasing concern that their widespread use may cause adverse effects within environmental and biological systems. Besides carcinogenic and neurotoxic effects, as well as effects on the reproductive system, the most obvious mammalian effects of both various di- and trisubstituted organotins were found on the immune system. Exposure of humans to organotin compounds can take place through consumption of contaminated fish and seafood. In human liver samples, mainly dibutyltin, the metabolite of tributyltin, could be detected indicating that organotin compounds are bioavailable after dietary exposure. The objective of this short review is to present various toxicokinetic aspects of organotin compounds in more detail. While several studies using in vitro systems investigated their metabolism especially by the monooxygenase system, various aspects of absorption, distribution, metabolism, and excretion (ADME) pathways of different organotin compounds were described by data obtained from several studies with laboratory animals. However, most of these studies were not conducted as full ADME studies but dealt only with some of these aspects. Therefore, for definitive conclusions in some cases, additional information is requested. By reviewing and updating the current literature consideration was given preferentially to those organotin compounds which have relevance with respect to human exposure and/or toxicological effects.