Evidence of polystyrene nanoplastic contamination and potential impacts in Mya arenaria clams in the Saint-Lawrence estuary (Canada)

Plastic materials found in the environment are expected to degrade into smaller plastic nanoparticles (NPs) posing a greater toxic risk because they sorb contaminants and pass physiological barriers. Moreover the pres-ence and effects of NPs is difficult to tease out from the contamination background at polluted sites. The purpose of this study was to examine for the presence of polystyrene NPs in feral Mya arenaria clam population near anthropogenic sources of pollution and potential toxic effects. Polystyrene NPs were determined by a newly developed fluorescence-based and size exclusion chromatography methodologies. Clam health status was determined by following changes in air survival time, condition factor, growth, alcohol/aldehyde dehydrogenase (AADH), protein aggregation and lactate dehydrogenase (LDH). In addition, multi-elemental analysis in tissues was also determined. The results revealed that clams collected at 2 polluted sites contained elevated amounts of polystyrene-like NPs between 10 and 110 nm in size based on size exclusion chromatography. Elevated levels of AADH suggest the presence of hydroxylated products and were correlated with plastic NPs in tissues. Moreover, principal component analysis revealed that As, Ca, Cu, Sn and V were closely related to either polystyrene-like NPs in tissues or AADH activity. Although we cannot rule out other pollutants, clams contaminated by polystyrene-like NPs had lower condition, growth rate, air survival time and LDH activity. Increased metal/ element contamination reported to sorb onto plastic polymers were also related to NPs in tissues. In conclusion, clams populations close to anthropogenic sources of pollution show evidence of polystyrene-like NPs contami-nation and could contribute to decreased clam health status.

Automated summary

This study aims to investigate the presence and potential toxic effects of polystyrene nanoparticles (NPs) in a feral Mya arenaria clam population near anthropogenic sources of pollution. The results show that clams collected from polluted sites contain polystyrene-like NPs ranging in size from 10 to 110 nm. These NPs are correlated with parameters such as alcohol/aldehyde dehydrogenase, indicating the presence of hydroxylated products. The contamination of clam populations by polystyrene-like NPs leads to decreased clam health status, including lower condition, growth rate, air survival time, and lactate dehydrogenase activity.