Background and Objective:
Marine environments can be contaminated by various anthropogenic persistent organic pollutants, such as petroleum-related (e.g., polycyclic aromatic hydrocarbons, PAHs), industrial (e.g., polychlorinated biphenyl, PCBs), and agriculture-related (e.g., organochlorine pesticides, OCPs) chemicals. Moreover, microplastic (MPs, particles < 5 mm) pollution of seawater is increasing in recent years and they can behave as a vehicle of chemicals acquired from the surrounding environment. Such MPs role is relevant from a public health perspective, increasing the exposure of beachgoers to harmful chemicals. In this paper, 40 field studies of MPs-sorbed organic pollutants were reviewed with the aim to understand the level of chemical contamination of MPs in the marine compartments.

Methods:
The literature search was conducted following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The keywords included microplastic in combination with the organic contaminants that could be adsorbed by MPs.

Results:
The methodology used for MPs-sorbed chemicals detection showed great differences among the studies, from sampling to analytical techniques. The most frequently searched chemicals were PCBs (55% of the reviewed papers) followed by PAHs (47.5%), and OCPs (42.5%). When such chemicals were searched, they were detected in almost one of the sampling sites included in each study. Overall, PCBs level showed a median concentration of 290 ng/g. The median PAH concentration was 3,595 ng/g, with an extremely high amount of 120,000 ng/g found in MPs from Chinese seawater. Dichlorodiphenyltrichloroethane was the most frequently detected OCP, with a median of 126.9 ng/g.

Conclusion:
This paper revealed that MPs can accumulate high level of chemicals in the marine environment, thus increasing the human exposure during swimming or rest on the beach. Despite the public health relevance of such human exposure, this topic is still little explored as demonstrated by the lack of standardized method for MPs collection and chemical analysis.