MPs risk assessment

The following equations (Wang et al. 2020) were used to generate the pollution load index (PLI), which was used to quantify the risk of MPs contamination (Kasamesiri et al. 2023).

where Ci is the MP concentration at sample site j and Co is the background MP concentration. The reference values for MPs were adopted according to worldwide records for sediments (1.79 items/kg DW) (Guo et al. 2021). PLIj was divided into four degrees of pollution by Guo et al. (2021).

Li et al. (2020) calculated the polymer risk index (H) as follows:

where Pn is the proportion of each polymer type at each sample site and Sn is the polymer hazard score calculated by Lithner et al. (2011), with PP = 4, PES = 4, and PE = 11. Lithner et al. (2011) and Guo et al. (2021) divided H into four levels: level I, < 10; level II, 10–100; level III, 100–1000; and level IV, > 1000.

RI Has been used to assess the ecological and toxicological consequences of MPs (Peng et al. 2018a, b; Ranjani et al. 2021).

Tj denotes the toxicity coefficient of MPs. Guo et al. (2021) identified five contamination thresholds for RI which are as follows: level I is less than 150, level II is 150–300, level III is 300–600, level IV is 600–1200, and level V is more than 1200.