Microplastics in water: diagnosis and human health risk analysis

Microplastics (MP) are present in various environments and are considered ubiquitous. Although contaminant identification is increasingly common, studies related to the risks associated with human health still challenge researchers. The aim of the present work was to investigate the presence of MP in water intended for human consumption and assess the possible risks associated with its ingestion. In the first step, with a methodological tool of a systematic review, an extensive literature search was made, which revealed that MP were detected in treated water at water treatment plants (WTP), that conventional coagulation and filtration processes were found to be effective in removing larger-sized MP (> 10 μm), while the efficiency is limited for the removal of MP < 10 μm, resulting in the persistence of these particles in treated water, especially in the range of 1 – 5 μm. Controlled filtration demonstrated the potential for MP removal, while advanced treatments showed no clear trends in behavior regarding these particles. For the standardization of MP studies in WTPs, guidelines for conducting research were proposed, suggesting that studies be conducted using LD > 1 µm by μRaman spectroscopy. In the second phase of this study, the aim was to evaluate human exposure to MP through the consumption of drinking water in adult males and females as well as in children. This was achieved through a series of calculations using deterministic and probabilistic assessments. The daily intake rate was estimated at 69 µg MP.d-1 , and proportional intakes based on body weight resulted in 0.92, 1.15, and 3.44 µg MP/kg bw/d for males, females, and children, respectively. The risk quotient (RQ) and sensitivity analysis were obtained through a probabilistic assessment (Monte Carlo). The monomers acrylamide, vinyl chloride and propylene oxide resulted in RQ > 10-5 , indicating carcinogenic effects. The RQ results for non-carcinogenic effects were below the limit of 1, both for the mean and the 95th percentile. The monomer methyl terephthalate resulted in a RQ between 0.2 and 1 for children, warranting attention." Ultimately, the main effects of MP on human health are related to genotoxicity. In conclusion, this study provided valuable insights into the presence of microplastics in human drinking water, highlighting potential concerns and providing a solid foundation for future investigations into the health impacts resulting from this exposure.