Drinking plastics? - Quantification and qualification of microplastics in drinking water distribution systems by mu FTIR and Py-GCMS

While it seems indisputable that potable water contains microplastics (MP), the actual concentrations are much debated and reported numbers vary many orders of magnitude. It is difficult to pinpoint the cause of these differences, but it might be variation between waters, variation between quantification methods, and that some studies did not live up to rigorous analytical standards. Despite the urgent need to understand human exposure by drinking water, there is a lack of trustable methods generating reliable data. Essentially, proper MP assessment requires that quality assurance is in place and demonstrated, that an adequate volume of drinking water is assessed, and that differences in analytical methods are understood. This study presents a systematic and robust approach where MP down to 6.6 mu m were assessed in potable water distribution systems in terms of quantity, size, shape, and material. For the first time, sub-samples were analysed by two of the most validated and complementary analytical techniques: mu FTIR imaging and Py-GCMS. Both methods successfully determined low contents in drinking water. However, mu FTIR and Py-GCMS identified different polymer types in samples with overall low MP content. With increasing concentration of a given polymer type, the values determined by the techniques became more comparable. Most detected MPs were smaller than 150 mu m, and 32% were smaller than 20 mu m. Our results indicate a potential annual uptake of less than one MP per person, suggesting that drinking potable water produced at a high-performance drinking water treatment plant represents a low risk for human health. (C) 2020 The Authors. Published by Elsevier Ltd.

Automated summary

The concentrations of microplastics in potable water are debated, likely due to variations in water quality, quantification methods, and analytical standards. Reliable methods for assessing microplastics in drinking water are lacking, but proper assessment requires quality assurance, adequate volume assessment, and understanding of analytical method differences. The study used validated techniques to assess microplastics in drinking water distribution systems and found low contents, suggesting low risk to human health.