A concise assessment of the risks to human health and the environment posed by exposure to triphenyltin compounds. These compounds, which are highly toxic to various species at extremely low concentrations, are used as fungicides to protect potatoes, sugar beets, hops, and celery, and to protect rice against fungal disease, algae, and mollusks. From the 1960s to recent years, triphenyltin compounds were used in antifouling paints for boats and fishnets, with catastrophic effects on the oyster industry and the aquatic ecosystem in general. As a result, use in antifouling paints is now restricted in many countries. Exposure of the general population occurs mainly through ingestion of contaminated seafood, which may contain very high levels. Studies of kinetics and metabolism in experimental animals indicate that triphenyltin compounds are not readily absorbed and are excreted primarily in the feces. Absorbed compounds accumulate in the kidney and liver.