Tissue-specific accumulation of triphenyltin compounds in marine fishes in sub-tropical Hong Kong

Abstract

The extensive use of organotin (OT) compounds in antifouling paints and other industrial uses (e.g. as fungicides, wood preservatives, and antibacterial textiles) have resulted in massive release of these compounds into urbanized coastal marine environments. Even though the International Maritime Organization (IMO) of the United Nations enacted a global prohibition on the usage of organotin-based antifouling agents on hulls of sea-going vessels in September 2008, Hong Kong had not adopted any regulatory legislation to restrict the production, usage and release of these compounds until early 2017. High concentrations of these compounds, especially triphenyltin (TPT), are still being detected in coastal marine environments of Hong Kong and Shenzhen, China. Organisms inhabiting these areas are particularly susceptible because they can bioaccumulate TPT through direct contact with contaminated seawater and sediment, and through dietary uptake. Nonetheless, a comprehensive tissue-specific accumulation profile of TPT compounds in marine fishes is still lacking, and such information will help reveal their toxicokinetics and identify targeted organs of accumulating these contaminants. This study was, therefore, designed to investigate the distribution pattern of TPT in the bodies of four marine fish species, namely Collichthys lucidus, Cynoglossus bilineatus, Johnius belangerii, and Johnius heterolepis. For each species, 15 tissue types (n = 4) were extracted for quantification of TPT concentrations and its degradation products (i.e., di- and mono-phenyltin) using gas chromatography mass-spectrometry. We found that the accumulation tendency of TPT was highly tissue-dependent. Highest concentrations of TPT were consistently found in livers, whereas scales and swim bladders contained the least amount of TPT. Mass-balance model showed that muscles (dorsal and ventral) generally contributed to 50% of the total body burden of TPT in these fishes on a wet-weight basis. Regression analysis suggested that TPT concentration of the whole organism could be predicted using its concentration in dorsal muscles (p < 0.05, r 2 = 0.973), which indicated that dorsal muscles can actually represent the contamination in the whole organism on dry-weight basis. Our findings from profiling the distribution pattern of TPT compounds would help identify potential TPT-induced organ-specific toxic effects in fishes, and investigate the potential of bio-magnification of TPT in marine food webs.