In a non-peer-reviewed scientific opinion column published on June 22, 2016 in the scientific journal Environmental Science & Technology, A. Dick Vethaak from research institute Deltares, Marine and Coastal Systems, and Heather A. Leslie from the Institute for Environmental Studies (IVM), VU University Amsterdam, both in the Netherlands, put forward an opinion that plastic debris pollution is not only a marine pollution issue, but also a human health problem.
Human exposure to plastic particles can occur via consumption of contaminated food and water, but also through the air. Three possible issues for adverse health effects include physical toxicity, chemical toxicity, and particles acting as pathogen and parasite vectors.
Particles as physical entities can cause not only lung and gut injury, but also cross cellular membranes, including placenta, the authors write. In their view, more studies are needed to better understand the “level of human exposure, chronic toxic effect concentrations and underlying toxicological mechanisms by which micro- and nanosized plastic particles elicit effects.”
Plastic debris contains not only macromolecular substances such as polymers, but also “micromolecular substances” including plastic monomers, chemical additives, and other environmental chemical pollutants that may sorb to plastic. Many of the latter compounds represent a known human health hazard, the authors state. Fine plastic particles may be able to cross cellular membranes and thus increase the bioavailability of chemical contaminants that they carry along. This ‘Trojan horse’ hypothesis has not yet been empirically verified, and urgently requires attention, the authors argue.
Recent studies have shown the presence of several species of human pathogenic bacteria in the marine plastic debris. Colonization of plastic debris with bacteria may occur in the wastewater treatment facilities where water from different sources is typically mixed together. Plastic debris can also create “favorable habitats” for disease-transmitting invertebrates, such as mosquitos or snails. Thus, the authors point out that high dispersal capabilities and the increasing amounts of plastic pollution around the world may pose novel challenges for pathogen management, especially in developing countries.
As main scientific research priorities, Vethaak and Leslie highlight the need to develop better analytical methods for particle detection in biological matrices, and the need to better understand the mechanisms and the extent of particle-caused adverse effects in humans.
Vethaak, A.D. and Leslie, H.A. (2016). “Plastic debris is a human health issue.” Environmental Science & Technology 50:6825-6826.