Microplastics are plastic particles less than 5 millimetres in size, produced by the fragmentation of larger plastic items or manufactured at small sizes for industrial applications. They are now distributed throughout every ecosystem on Earth, including Arctic sea ice, deep ocean sediment, and atmospheric precipitation. In 2022, microplastics were detected in human blood for the first time by a Dutch research group. Subsequent studies have found them in lung tissue, intestinal tissue, placental tissue, and breastmilk. The health implications of this ubiquitous internal exposure are under active scientific investigation, but sufficient evidence exists to justify precautionary exposure reduction.
What Microplastics Carry: The Chemical Concern
The toxicological concern with microplastics is not only the plastic particles themselves but the chemicals they carry. Plastic polymers contain plasticisers, flame retardants, UV stabilisers, and other additives. They also adsorb persistent organic pollutants, heavy metals, and other environmental contaminants from the surrounding medium, concentrating them on their surfaces. When ingested or inhaled, microplastics may release these adsorbed chemicals in biologically active environments, with potentially greater exposure than direct environmental exposure to the same compounds.
Routes of Exposure and Current Evidence
Dietary sources are the primary route of microplastic ingestion, particularly seafood consumed whole, bottled water, foods packaged or processed in plastics, and salt. A 2019 WWF study estimated that the average person may be ingesting approximately 5 grams of microplastic per week, equivalent to a credit card, though this figure requires replication with standardised methodology. Inhalation of airborne microplastics is a second significant route, with indoor air estimated to contain higher concentrations than outdoor due to textiles, upholstery, and dust accumulation.
Precautionary Exposure Reduction
While definitive cause-and-effect evidence for microplastic health harm in humans remains under investigation, the precautionary principle justifies practical reduction measures, particularly given that most high-impact steps have co-benefits for reducing other contaminant exposures simultaneously. Drinking filtered tap water rather than bottled water reduces plastic particle intake: studies have found that bottled water contains significantly more microplastic particles than filtered tap water. Reducing plastic food contact, particularly with heat, reduces plastic monomer and additive migration.
- Use a quality water filter for drinking water rather than plastic bottled water
- Store and heat food in glass, ceramic, or stainless steel rather than plastic
- Vacuum and damp dust regularly to reduce indoor airborne microplastic from textile and upholstery sources
- Wash synthetic clothing in a microplastic-catching laundry bag to reduce domestic fibre release
- Reduce single-use plastic in food contact: cling film, plastic bags, and single-use containers are high-contact sources
Sources
- Leslie, H.A., et al. (2022). Discovery and quantification of plastic particle pollution in human blood. Environment International, 163, 107199.
- Cox, K.D., et al. (2019). Human consumption of microplastics. Environmental Science and Technology, 53(12), 7068-7074.