Immunotoxic effects of the antifouling compound sea-nine 211tm on haemocytes of an edible bivalve mollusc

Sea-Nine 211TM (4,5-dichloro-2-n-octyl-4-isothiazolin- 3-one) has recently been introduced as a primary biocide in the formulations of new antifouling paints for the boat hulls in place of the organotin compounds. In this study, immunotoxic effects of various sublethal concentrations - 0.1 to 10 μM - of Sea-Nine 211TM on the edible Manila clam Ruditapes philippinarum were evaluated in vitro. By means of assays with short-term haemocyte cultures, the influence of the xenobiotic on both cell morphology and functionality was evaluated. Although no effect on cell adhesion was observed, severe and irreversible morpho-functional effects occurred similarly to those reported for organotin compounds. At 1 μM (282.2 μg/l), Sea-Nine 211TM exerted significant (p < 0.001) inhibitory effects on cell spreading, yeast phagocytosis, hydrolytic enzyme (β-glucuronidase) activity, induced apoptosis and caused oxidative stress, the latter demonstrated through a decrease in cytoplasmic glutathione content. Data suggest that the biocide Sea-Nine 211TM is immunotoxic and represents a potential risk for benthic filter-feeding invertebrates living in the water- sediment interface and, as a consequence of bioaccumulation, for human health. However, further studies need to validate functional responses of clam haemocytes as immunomarkers in field conditions, like those measured in the present study in Sea-Nine 211TM-exposed cells.