The results showed that most of these particles, approximately 90%, were classified as nanoplastics. The chemical composition of the fragments revealed a predominance of polyethylene terephthalate (PET), a polymer widely used in bottle production, along with other materials like polypropylene and polyamide.

The data indicates that the presence of nanoplastics in bottled water is a widespread phenomenon, likely originating from the abrasion of packaging materials. The nanometric size of these particles raises concerns about their interaction with biological systems, as they are theoretically capable of crossing cell membranes and other physiological barriers. The study's conclusions suggest the need for further research to assess actual human exposure and to understand the potential long-term effects of these particles on the body. This investigation helps provide a more complete picture of plastic contamination at the micro and nanoscopic levels, outlining new directions for research in food and environmental safety.

Differences between tap water and bottled water in global contexts
The issue of water quality isn't limited to nanoplastics; there are significant differences between tap water and bottled water depending on the geographical context.

Regulation and quality standards

Tap water: in most high-income countries (such as the European Union, the United States, Canada, and Australia), drinking water is subject to strict regulations from public health agencies. The standards for public water supplies are often more stringent than those applied to bottled water, which is classified as a food product. Testing is frequent, and the results are usually public.

Bottled water: bottled water is regulated by food standards that can vary considerably and, in many cases, are less strict than those for tap water. As a result, checks for micro- and nanoplastics, for example, are not always mandatory, and quality information is not always easily accessible to the public.

Presence of contaminants

Comparative studies suggest that tap water generally contains fewer microplastics than bottled water. The main source of contamination in bottled water is the packaging material itself (PET). In contrast, the primary sources of contamination for tap water, when present, are obsolete water infrastructure (like lead pipes) or wastewater contamination.

Global context

High-income countries: tap water is generally considered safe and, in many cases, of higher quality than bottled water. The preference for bottled water is often linked to perceptions of purity, taste, or convenience, rather than a genuine need for safety.

Developing countries: in many areas with limited or unreliable water infrastructure, bottled water is often perceived as, and sometimes is, the safer option for consumption. This is due to a lack of trust in the public distribution system and the widespread presence of pathogens. However, even in these cases, the presence of nanoplastics remains an unresolved problem.

References

Zhang J. et al. Rapid, multiplexed, single-particle imaging of nanoplastics and microplastics in bottled water J. Environ Expo Assess 2024;3:24. https://www.oaepublish.com/articles/jeea.2024.37