Passive sampling-derived aqueous concentrations of organotins and booster biocides in the largest Port of South America (Southeastern Brazil).

Organotin compounds (OTs) used to be the most widely used biocide in antifouling paint systems, but the International Maritime Organization (IMO) banned them because of their high environmental toxicity to non-target organisms. Currently, at least 25 active ingredients are being employed as biocides in antifouling paint formulations. In the present study, silicone rubber-based passive sampling was used to determine the freely dissolved concentrations (Cw) of 6 OTs and 4 booster biocides in the water column at the entrance of Santos Port's main navigation channel, the largest Port of South America (southeastern Brazil). Fifteen sampling events of ∼45 days long were conducted over 2 years. Cw of OTs ranged from 1.1 to 2.5 ng Sn L-1 for monobutyltin (MBT), 0.2 to 4.7 ng Sn L-1 for dibutyltin (DBT), and 0.06 to 0.7 ng Sn L-1 for tributyltin (TBT), while triphenyltin (TPhT), diphenyltin (DPhT), and monophenyltin (MPhT) were always below their limits of detection (