Interactive effects of microplastics and benzo[a]pyrene on two species of marine invertebrates

This study aimed to evaluate B[a]P and low-density polyethylene microplastics (MPs) toxicty, alone and in mixture (0.03 to 30 μg L−1 of B[a]P; and 5, 50 and 500 mg L−1 for MPs). Five mg L−1 of MPs is considerably higher than commonly reported environmental concentrations, although it has been reported for marine environments. Individual (sea urchin embryo-larval development and mortality of mysids) and sub-individual responses (LPO and DNA damage in mysids) were assessed. The toxicity increased as the B[a]P concentration increased, and microplastics alone did not cause toxicity. B[a]P toxicity was not modified by the lowest concentration of MPs (5 mg L−1), but at higher MPs concentrations (50 and 500 mg L−1), the effects of B[a]P on sea urchin development and in biomarkers in mysids were diminished. Microplastics interacted with B[a]P in seawater, reducing its toxicity, probably due to adsorption of B[a]P to the surface of microplastics. [Display omitted] •Microplastics are important carriers of contaminants and can alter their toxicity.•Biological responses in two species of marine invertebrates were assessed.•Microplastics and B[a]P interact modifying the toxicity of the isolated elements.•B[a]P toxicity was not modified by environmental concentrations of microplastics.•B[a]P toxicity decreased at higher concentrations of microparticles.