Ecological risk assessment of booster biocides in sediments of the Brazilian coastal areas

Although booster biocides (Irgarol, diuron, chlorothalonil, dichlofluanid, and DCOIT) have been detected in sediments along the Brazilian coastal areas, the risk associated to their occurrence and levels is still unknown. Thus, the ecological risk of booster biocides to sediment-dwelling organisms from the Brazilian coast was assessed using a risk characterization approach through the Risk Quotient (Measured environmental concentration (MEC)/Predicted no effect concentrations (PNECs)). Sedimentary PNECs for Irgarol, diuron, chlorothalonil and DCOIT were derived based on published ecotoxicological data from both freshwater and marine studies, while a NORMAN methodology was used to derived it for dichlofluanid. Results showed that DCOIT, diuron, Irgarol, chlorothalonil, and dichlofluanid can pose high risk on 47%, 35%, 15%, 1% and 1%, respectively, of the 113 Brazilian sites appraised. Considering the trend of expansion of navigation/maritime activities, DCOIT may worsen its impact over the coastal areas of Brazil, especially ports, but also ship/boatyards, marinas, and maritime traffic zones. The present study is an important contribution to support advance on policy formulation concerning booster biocides worldwide, particularly considering the lack of regulation on the use of antifouling biocides in Brazil.