Microplastics have been found to persist in the environment in large quantities, especially in marine and aquatic ecosystems. This is because plastic deforms but does not break for many years, and can be ingested and accumulated in the body and tissues of many organisms.
The entire cycle and movement of microplastics in the environment has not yet been studied in depth, especially due to the difficulty of analyzing a mixture of various types of more or less inert plastics. Microplastics come from different sources: they are found massively in products such as cosmetics, personal care and household products, building materials and in industries and agriculture.
Often in cosmetics, microplastics make up up to 90% of the total weight of the product, as in the case of skin exfoliants. Agriculture is also a producer of microplastics. The sheets that are used to mulch disintegrate in the soil when at the end of the crop cycle they are not collected and disposed of properly.
Left on the ground, plastics can degrade by abrasion, by atmospheric agents or by the action of insects or mammals. A large amount of microplastics is of home origin, such as those coming from the washing of synthetic garments, which are poured into water.
One of the biggest fears of all relates to the contamination of drinking water. The article: Microplastic contamination of drinking water: A systematic review, published on PloS one, said: "Microplastics (MPs) are omnipresent in the environment, including the human food chain; a likely important contributor to human exposure is drinking water.
To undertake a systematic review of MP contamination of drinking water and estimate quantitative exposures. The 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. 12 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 (I2> 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 analyzed, 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. This 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 standardize experimental protocols to aid comparison and elevate quality. "