Global plastic production has increased exponentially over the past decades. A significant proportion of the plastic produced is not disposed of properly and persists in the environment, especially the marine environment. Plastic products can be slowly degraded into smaller pieces (micro- or even nanoplastics). Furthermore, micro-plastics are intentionally added to, for example, toothpaste and beauty products (referred to as microbeads) or are a secondary by-product of rubber from, e.g. textiles, tyre wear or artificial turf.
Plastic debris is associated with a “cocktail of contaminants” made up of chemical ingredients present originally in the plastic and chemical pollutants adsorbed to the plastic from the environment, including metals and other persistent contaminants such as polychlorinated biphenyls (PCBs) and flame retardants. The debris is filtered into marine species’ gastrointestinal tract mechanically or it may look like food to some species, thus entering the food chain, with unknown effects.
Risk assessments and reviews carried out in recent years have concluded that there is evidence that humans are exposed to micro- and nano-plastics through their diet, drinking water or inhalation. However, our understanding of the fate and toxicity of these plastic particles in humans constitutes a major knowledge gap, rendering it difficult to carry out proper science-based risk assessment and management.
Proposals should use innovative approaches to provide policy relevant scientific data in support of improved human health hazard and risk assessment of micro and/or nano-plastics.
The following research priorities on micro- and/or nano-plastics, inter alia, can be considered:
- Environmental/food/water sources for micro- and/or nano-plastics and transmission to humans;
- Methods for identification and quantification of micro and/or nano-plastics in foods, environmental media and tissues;
- Exposure levels of humans to micro- and/or nano-plastics and methods for human biomonitoring;
- Analytical methods for detection of micro- and/or nano-plastics particles and contaminants;
- Microbial colonisation of micro- and/or nano-plastics as vectors for potential pathogens;
- Micro- and/or nano-plastics as condensation nuclei and/or carriers for airborne particulate matter and chemicals harmful to health;
- Toxicology and uptake of micro- and/or nano-plastics and additives/adsorbed contaminants;
- Fate of micro- and/or nano-plastics in the gastro-intestinal or respiratory tracts and secondary organs;
- Effects and transport of micro- and/or nano-plastics across biological barriers, and bioaccumulation and cell uptake of micro- and/or nano-plastics, including studies at the cellular and molecular levels;
- Consideration of the effect of shape (as well as size) of micro- and/or nano-plastics, and comparison with the behaviour and effects of non-synthetic homologues, e.g. wool fibres;
- Immune responses;
- Preliminary investigations into long-term effects of micro- and/or nano-plastics.
Sex and gender differences should be investigated, where relevant.