Organotin pollution at Arraial do Cabo, Rio de Janeiro State, Brazil: increasing levels after the TBT ban

Abstract

Imposex, an endocrine disruption phenomenon, is a biomarker of tributyltin (TBT) exposure in marine gastropod populations. The occurrence and intensity of the syndrome in populations of the neogastropod Stramonita haemastoma were ascertained at nine sampling stations in October 2008 at Arraial do Cabo, a very important tourist resort in Rio de Janeiro state (Brazil) and part of the Marine Extractive Reserve of Arraial do Cabo. The results obtained made it possible to evaluate the changes which had occurred since the last biomonitoring campaign, undertaken in 2001, at these same stations. Despite the ban on the use of TBT imposed by the Brazilian Navy in 2003, the controls on the use of this agent in Brazil resulting from the establishment of NORMAM 23 by the Navy in 2007 and the complete ban of organotin compounds in antifouling paint formulae by the IMO on a global scale in 2008, imposex was still detected. Instead of the expected reduction, an increase was observed in the areas affected by imposex. Furthermore, populations in the areas seriously affected by imposex in 2001 were absent in the 2008 sampling campaign. These results suggest an increase in TBT pollution in the study area, indicating the inefficacy of legislative measures.