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IMMUNOTOXICITY OF ORGANOTINS USED AS STABILIZERS IN PVC PIPE
Impact/Purpose:
OBJECTIVE: 1. Evaluate the immunotoxicologic potential of mono- and dimethyl, and mono- and dibutyl tins following maternal or adult oral exposure to single (to the extent possible) chemicals. 2. Evaluate the immunotoxicologic potential of methyl- and butyltins mixtures at ratios representative of those reported in leachate from PVC pipe.
Description:
Organotins, used as stabilizers in the production of PVC drinking water supply pipe, are known to leach into water, particularly from new pipe. Certain organotins (dibutyl-, dioctyl- and tributyltins) are known to suppress immune function following acute and subchronic exposure of adult animals. Furthermore, the developing immune system is more sensitive to dioctyl- and tributlytin than that of the adult: smaller doses are required to significantly suppress immune function, and recovery of normal function is delayed when exposure of the immature system occurs. At least in rodents, the fetus and neonate appear to be protected from maternal exposure to DOTC and TBTO by very poor placental and lactational transfer of these compounds. In contrast, methyl- and butyltin dosing of pregnant rats has been reported to cause neurotoxicity and terata in offspring, suggesting that both classes of organotin cross the placenta. This project will evaluate the effects of mono- and disubstituted methyl and butyl tins on the developing and adult immune systems. The goals of this project are to determine 1) whether these compounds are developmental and/or adult immunotoxicants; 2) the relative potency of these chemicals; 3) the persistence of altered immune function following developmental or adult exposure. In addition, if results warrant further study, a representative mixture of the organotins will be tested. These studies will provide ODW with data on the potential immunotoxicity of organotin stabilizers that may leach into drinking water, as single entities and as a mixture.