Interactions of microplastics with contaminants in freshwater systems: a review of characteristics, bioaccessibility, and environmental factors affecting sorption

Abstract

Microplastics (MPs), plastic particles of 1 nm to <5 mm, have been identified in the atmosphere, soil, and aquatic environments across the globe. MPs may act as vectors to transport environmental contaminants to sensitive receptors, including humans. In this review, the capability of MPs to sorb persistent organic pollutants (POPs) and metals is investigated, along with how sorption is affected by factors, such as pH, salinity, and temperature. Sensitive receptors may take up MPs through incidental ingestion. In the gastrointestinal tract (GIT), contaminants may desorb from MPs, and this desorbed portion is then considered bioaccessible. Understanding the sorption and bioaccessibility of such contaminants is important in determining potential risks of exposure to MPs. Thus, a review is presented on the bioaccessibility of contaminants sorbed to MPs in the human and avian GIT s. The current state of knowledge on MP-contaminant interactions in freshwater systems is limited; these interactions can differ considerably from those in marine environments. The bioaccessibility of contaminants sorbed to MPs can vary significantly, from near zero to 100%, depending on MP type, contaminant characteristics, and the digestive phase. Further research is needed to characterize the bioaccessibility and the potential risks, especially for POPs associated with MPs.

Graphical abstract

Keywords:

• Vector effect
• associated contaminants
• human health
• avian contamination
• risk assessment
• metal contaminants
• organic contaminants
• contaminant transport
• incidental ingestion
• in-vitro digestion model

Disclosure statement

Data are available upon request.

Data availability statement

The authors declare no potential competing interests.

Additional information

Funding

This work was supported by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) to the corresponding author under Grant #RGPIN 2018-04136.