Accumulation of butyltin compounds and total tin in marine mammals

Concentrations of butyltin compounds (BTs), including tributyltin (TBT) and its metabolites, di-(DBT) and monobutyltin (MBT), and total tin (ΣSn=organic+inorganic tin) were determined in various tissues and organs of marine mammals collected from Japanese coastal waters. Some marine mammal species from Hong Kong, India, Philippines, Black Sea and North Pacific Ocean were analyzed for comparison. Among the organs and tissues analyzed, concentrations of ΣBTs (TBT+DBT+MBT) and ΣSn were the highest in the liver. Concentrations of ΣBTs and ΣSn in most coastal species were higher than those in offshore species, indicating a greater input of tin compounds in coastal waters. Lower hepatic concentrations of ΣBTs and ratio of ΣBTs to ΣSn observed in pinnipeds may be attributed to higher metabolic capacity to degrade BTs and to their excretion through hair shedding. Age trends in accumulation of both ΣBTs and ΣSn showed increasing concentrations in immature growth stage and stable levels in mature animals.A significant correlation was observed between the hepatic concentrations of ΣBTs and ΣSn in marine mammals. These findings suggest a significant input and/or bioaccumulation of anthropogenic tin. A significant correlation was found between concentrations of ΣBTs (as well as ΣSn) in hair and liver of pinnipeds, suggesting that hair can be used as an indicator for monitoring butyltin contamination in the body of pinnipeds under non-killing condition.