Microplastics have been detected in many environmental samples and living organisms. Not only are their health effects still being studied, but how and in what amounts they are taken up by humans is not yet well-known. A recent modeling study and review have improved the general understanding of their total uptake, pointing to significant increases in recent years, large global differences, and increased uptake of microplastics associated with high seafood consumption.
Xiang Zhao and Fengqi You from Cornell University modeled the uptake of microplastics via inhalation and dietary uptake, including microplastics generated from food packaging. Their model covers how microplastic uptake changed over time and how different countries are impacted.
Dietary intake is particularly high in Southeast Asian countries (up to 500 mg/person/day), originating mainly from high seafood consumption. The rapidly industrializing nations in the regions, like Indonesia, Malaysia, the Philippines, and Vietnam, are particularly impacted, with more than 70% of dietary microplastics thought to be taken up from seafood. A large portion of these microplastics can be traced back to plastic pollution.
Their model also suggests that in many countries microplastic uptake has grown on average 6-fold from 1990 to 2018, and up to 20-fold in particularly burdened regions. The main drivers of this increase are identified as increased plastic production and inadequately managed plastic waste. Microplastic pollution and uptake have grown particularly fast in Eastern Asia, especially in Laos, China, and Indonesia, but also in Egypt.
Food packaging is the primary source of litter in all aquatic environments except the deep ocean (FPF reported). Many countries in Southeast Asia are implementing extended producer responsibility schemes and banning certain single-use plastic products, but monitoring and implementation can be difficult (FPF reported). This can be exacerbated by waste imports from other nations (FPF reported).
Chukwuebuka Gabriel Eze from the University of Nigeria together with colleagues tackled a similar question regarding the most important dietary sources of microplastics in a recent qualitative review. There is considerable variation in the reported microplastic concentrations in foods due to different analytical methods and microplastic definitions (FPF reported). While there are still some questions regarding the pathways of microplastic contamination in the food chain that require further investigation, the most significant sources of dietary microplastics appear to be food packaging, drinking water, and foods that have been contaminated by water, such as seafood or sea salt. Food packaging may be directly responsible for around 2.98 × 103 microplastics/person/year, with even higher intakes for people who regularly consume bottled water, tea brewed from plastic tea bags, or ultrafiltered milk.
The authors of both studies suggest that better waste management, increased clean-up of plastic pollution, and a switch to alternative materials, such as edible and/or biodegradable materials are important ways forward. Several Nigerian municipalities banned foamware and other single-use plastics in early 2024 (FPF reported) as a step toward reducing plastic pollution. In addition, the authors estimate that up to 60% of human microplastic uptake could be mitigated by removing 99% of current plastic pollution from aquatic environments. Achieving such high clean-up rates is not possible with current plastic pollution removal technologies.
References
Eze, C.G., Nwankwo, C.E., Dey, S. et al. (2024) “Food chain microplastics contamination and impact on human health: a review.” Environmental Chemistry Letters. DOI: 10.1007/s10311-024-01734-2
Zhao, X, and You, F. (2024). “Microplastic Human Dietary Uptake from 1990 to 2018 Grew across 109 Major Developing and Industrialized Countries but Can Be Halved by Plastic Debris Removal.” Environmental Science and Technology. DOI: 10.1021/acs.est.4c00010
Read more
Pironti, C., Ricciardi, M., Motta, O., et al. (2021). “Microplastics in the Environment: Intake through the Food Web, Human Exposure and Toxicological Effects.” Toxics. DOI: 10.3390/TOXICS9090224
