Comparison of biofilm-covered microplastics and sand particles as vectors of PCB-153 to Paracentrotus lividus

The microplastics (MPs) vector effect of environmental contaminants (such as polychlorinated biphenyls-PCBs) to organism tissues is currently one of the major concerns regarding MPs pollution in the marine environment. The relative importance of MPs as vectors for the bioaccumulation of contaminants to marine organisms compared to other naturally occurring particles has been poorly investigated and never by using biofilm-covered particles. The present study compares the role of biofilm-covered microplastics and sand particles as vectors for the transfer and bioaccumulation of ¹⁴C-PCB-153 into various body compartments of the sea urchin Paracentrotus lividus. After 14 days of exposure, similar transfer efficiency of ¹⁴C-PCB-153 from both types of biofilm-covered particles was obtained (t-test, p-val = 0.43). The particle type was not found to affect the concentration (two-way ANOVA, p-val_{per dry weight} = 0.92, p-val_{per lipid weight} = 0.80) and distribution (two-way ANOVA, p-val = 0.85) of ¹⁴C-PCB-153 among the different body compartments of sea urchins. These findings suggest that biofilm-covered MPs located on the seafloor may act as similar vectors for the bioaccumulation of PCB-153 in sea urchin tissues compared to other biofouled natural particles such as sand. Overall, the outcomes of this present work align with the growing consensus among various research groups that MPs-mediated bioaccumulation of co-contaminants would be negligible compared to natural bioaccumulation pathways in relation to their abundance in the ocean.