Not only food packaging can be a source of chemical contamination in food, but migration can occur also from other articles that come into contact with food such as processing equipment or distribution systems. In an article published on September 20, 2022, in the journal Environmental Science and Pollution, Azam Mohammadi from Kerman University of Medical Sciences, Iran, and co-authors investigated the current scientific knowledge on the migration of microplastics, bisphenol A (BPA), phthalates, nonylphenol (NP), and per- and polyfluoroalkyl substances (PFAS) from pipes used in drinking water distribution systems worldwide. In particular, they were interested in the occurrence of these five chemical groups, their sources related to material type, and their potentially related hazards. Drinking water distribution systems include pipes, valves, and water reservoir tanks.
To identify the relevant peer-reviewed publications on the topic, the authors searched Scopus, PubMed, Science Direct, Web of Science, ProQuest, Springer Link, and Publons for defined keywords. A total of 92 articles met the inclusion criteria and were included in the review. Mohammadi and co-authors summarize that microplastics, BPA, phthalates, NP, and PFAS present in drinking water “may stem from migration from pipes or reservoirs.” They further found that tap drinking water in contact with pipes made of polymers “had the highest mean concentrations of reviewed contaminants.” In general, the pipe’s material type was reported to influence the migration of the five contaminant groups into water during transportation and storage. Concerning microplastics, polyvinyl chloride (PVC), polyamide (PA), polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET) were the polymer types of microplastics most frequently detected in tap water.
By using the maximum concentrations detected across all reviewed studies, Mohammadi et al. also assessed health risks. They found that “some contaminants in the tap drinking water of some countries raise a potential health risk for humans as the hazard index values determined for them were above 1” indicating a “significant risk of relevant health effects.” This was for instance the case for specific PFAS detected in tap water in Germany, France, South Korea, and Ghana for non-carcinogenic health effects. Moreover, levels of bis(2-ethylhexyl) phthalate (DEHP, CAS 117-81-7) and benzyl butyl phthalate (BBP, CAS 85-68-7) in some samples were reported to be a carcinogenic health risk for adults and children. Therefore, the scientists concluded that “the output of drinking water from pipelines can be an important pathway for exposure to emerging contaminants.”
The authors also summarized the factors that influence the release of chemicals. Overall, higher temperatures and longer contact times were associated with higher contaminant levels and pipe age was associated with higher microplastic levels. While most studies assessed phthalates and PFAS, fewer studies looked at microplastics, BPA, and NP. The review further showed a large difference in research attention on contaminants in tap drinking water between countries, with most studies conducted in China and generally more studies in Europe compared to Asia, Africa, and the Americas.
Measures recommended by the author to mitigate chemical migration from pipes into drinking include a careful selection of suitable pipe types, regular cleaning of the pipes, as well as regulatory limitations of contaminant use in manufacturing of the pipes. As an example, Sweden has banned BPA in water pipe linings (FPF reported). Furthermore, Mohammadi and co-authors point out that contaminants would be diluted by the high water volume, which makes it necessary to take measurements at several locations in the distribution network and especially at the beginning.
Reference
Mohammadi, A. et al. (2022). “Emerging contaminants migration from pipes used in drinking water distribution systems: a review of the scientific literature.” Environmental Science and Pollution Research. DOI: 10.1007/s11356-022-23085-7
