Contamination of French Coastal Waters by Organotin Compounds: 1997 Update

Fifteen years ago, France took regulatory measures to limit the use of organotin compounds in antifouling paints for the protection of boat hulls. France was the first country to take these emergency steps, which were intended to defend the oyster-farming industry. Since then, the regulations have been confirmed on several occasions, most recently in October 1992. What is the situation at the present time? The campaign conducted by IFREMER from July to September 1997 to measure organotin compounds in seawater provided an update. The contamination of French coasts is still a problem, and the measurements obtained showed persistent sources of pollution for many port facilities. Concentrations measured in the coastal area outside port facilities very often exceeded recognized toxic levels. Seventy-five percent of the measurements were above the threshold of 1 ng.l −1, which is known to cause toxic effects for some marine species. There was considerable variability in the results for the 237 measurement points sampled. In general, the eastern English Channel and the French Riviera are the regions concerned most systematically by excessive levels. The tributyltin concentration was 4.6 ng.l −1 on average, but for ten stations, the contamination was above 100 ng.l −1. The improvement noted during the 1980s has ceased. Comparison with the previous assessment performed by IFREMER in 1992 indicates that the situation today has stagnated at levels which are still far too high. Regulations and monitoring remain necessary. The development of non-toxic alternatives to organotin antifouling paints is required.