Hazard of novel anti-fouling nanomaterials and biocides DCOIT and silver to marine organisms

Abstract

Biocide-based coatings have been applied for several years to tackle marine biofouling. Recently, engineered nanomaterials, such as silica mesoporous nanocapsules (SiNCs), were used to encapsulate DCOIT, an anti-fouling booster biocide, and Ag, a broad-spectrum bactericidal agent, in order to control their release with time. This study aims to assess the environmental hazard of three novel anti-fouling nanomaterials (SiNC–DCOIT, SiNC–Ag and SiNC–DCOIT–Ag) and their free counterparts (DCOIT, Ag and SiNCs) to marine ecosystems. In order to accomplish this goal, marine toxicity data (L/E/IC₅₀ or NOEC) were compiled to derive PNEC values for each compound based on statistical and deterministic approaches. The first approach relies on the hazardous concentration for 5% of the species (HC₅ using species sensitivity distribution curves) and the second relies on the lowest L/E/IC₅₀ or NOEC value, considering the appropriate assessment factors. In both approaches, PNEC values were lower for the encapsulated biocides than for their free forms. Thus, biocide encapsulation appears to be a promising solution to develop a new generation of efficient anti-fouling additives for maritime coatings with lower environmental hazard than the current state-of-the-art biocides.