Microplastic contamination of drinking water: a systematic review.

BackgroundMicroplastics (MPs) are omnipresent in the environment, including the human food chain; a likely important contributor to human exposure is drinking water.ObjectiveTo undertake a systematic review of MP contamination of drinking water and estimate quantitative exposures.MethodsThe protocol for the systematic review employed has been published in PROSPERO (PROSPERO 2019, Registration number: CRD42019145290). MEDLINE, EMBASE and Web of Science were searched from launch to the 3rd of June 2020, selecting studies that used procedural blank samples and a validated method for particle composition analysis. Studies were reviewed within a narrative analysis. A bespoke risk of bias (RoB) assessment tool was used.Results12 studies were included in the review: six of tap water (TW) and six of bottled water (BW). Meta-analysis was not appropriate due to high statistical heterogeneity (I 2 >95%). Seven studies were rated low RoB and all confirmed MP contamination of drinking water. The most common polymers identified in samples were polyethylene terephthalate (PET) and polypropylene (PP), Methodological variability was observed throughout the experimental protocols. For example, the minimum size of particles extracted and analysed, which varied from 1 to 100 μm, was seen to be critical in the data reported. The maximum reported MP contamination was 628 MPs/L for TW and 4889 MPs/L for BW, detected in European samples. Based on typical consumption data, this may be extrapolated to a maximum yearly human adult uptake of 458,000 MPs for TW and 3,569,000 MPs for BW.ConclusionsThis is the first systematic review that appraises the quality of existing evidence on MP contamination of drinking water and estimates human exposures. The precautionary principle should be adopted to address concerns on possible human health effects from consumption of MPs. Future research should aim to standardise experimental protocols to aid comparison and elevate quality

Microplastic contamination of seafood intended for human consumption: a systematic review and meta-analysis

Background: Microplastics (MPs) have contaminated all compartments of the marine environment including biota such as seafood; ingestion from such sources is one of the two major uptake routes identified for human exposure.Objectives: The objectives were to conduct a systematic review and meta-analysis of the levels of MP contamination in seafood, and to subsequently estimate the annual human uptake.Methods: MEDLINE, EMBASE and Web of Science were searched from launch (1947, 1974 and 1900, respectively) up to October 2020 for all studies reporting MP content in seafood species. Mean, standard deviations (SD) and ranges of MPs found were collated. Studies were appraised systematically using a bespoke Risk of Bias (RoB) assessment tool.Results: Fifty studies were included in the systematic review and 19 in the meta-analysis. Evidence was available on four phyla; molluscs, crustaceans, fish and echinodermata. The majority of studies identified MP contamination in seafood and reported MP content below 1MPs/g (microplastics per gram), with 26% of studies rated as having high RoB, mainly due to analysis or reporting weaknesses. Molluscs collected off the coasts of Asia were the most heavily contaminated, coinciding withreported trends of MP contamination in the sea. According to the statistical summary, MP content was 0-10.5 MPs/g in molluscs, 0.1-8.6 MPs/g in crustaceans, 0-2.9 MPs/g in fish and 1MPs/g in echinodermata. Maximum annual human MP uptake was estimated to be close to 55,000 MP particles. Statistical, sample and methodological heterogeneity was high.Discussion: This is the first systematic review, to our knowledge, to assess and quantify MP contamination of seafood and human uptake from its consumption, suggesting that action must be considered in order to reduce human exposure via such consumption. Further high-quality research using standardized methods is needed to cement the scientific evidence on MP contamination and human exposures

Outdoor atmospheric microplastics within the Humber region (United Kingdom): Quantification and chemical characterisation of deposited particles present

Atmospheric microplastics (MPs) have been consistently captured within air samples on a global scale. Locations with high human activity are reported to have high MP levels. An urban sampling site in the Humber region (U.K.) has been sampled over a 13-month period, providing a seasonal variation profile of MP levels, size, shape, and polymer types that humans are exposed to. Mean MP levels, measured using passive fallout into a container, were 3055 ± 5072 MP m−2 day−1 (1164 median). An increase in levels with a decrease in MP size was observed, consisting of mainly film-shaped MPs (67%) that were polyethylene (31%) and nylon (28%) polymer types. No relationship between rainfall and MP fallout levels was observed. In parallel, MPs within five urban-ised locations relevant to human exposure were characterised over a 2-week period. An overall MP mean (and standard deviation) of 1500 ± 1279 was observed (1012 median), from which petroleum resin accounted for 32% of MP polymer type, with a higher prevalence within industrial and roadside zones. These comprised mainly fragment (52%) and film (42%) shapes, and the MPs levels increased with decreasing particle size. The results provide novel information on characterising polymer levels and types, and can inform cellular toxicity studies, investigating the consequences of human MP exposure