Microplastics are generally considered to be small plastic particles less than about 5mm in size. Primary microplastics are small to begin with, such as microbeads that are added to personal care products. Secondary microplastics, on the other hand, start off as larger plastic items, such as plastic bags, but degrade into microplastic particles over time.
Recently, there's been increasing interest in the effects of microplastics pollution. Media reports have examined microplastics pollution, especially in the marine environment, and possible contamination of the food supply.
Most research to date has been on microplastics in the marine environment. Plastic litter can enter our seas and oceans, where it never completely breaks down. Instead, it 'breaks up' into smaller and smaller particles eventually becoming microplastics. The UV radiation from sunlight contributes to this process of degradation.
Light and buoyant microplastics can travel great distances on our oceans' currents. They can be found at the oceans' surface, on the beaches, in arctic sea ice and deep sea sediments. Microplastics are eaten by fish, seabirds and other marine life, who mistake these for food. Once eaten by aquatic animals, they can potentially become part of the human food chain.
But this may not be the only way microplastics can enter our food chain. Studies have looked at their possible presence in sea salt, honey, beer, bottled water, organic fertilisers used on backyard gardens, and even in indoor dust settling on our meals.
The scientific evidence on potential exposures and health risks of microplastics in the food supply is still evolving. However, available scientific studies and reports suggest that:
- Human exposure to microplastics from eating finfish is likely to be negligible. This is because the microplastics are found in the gills, liver and intestines of the finfish, which are organs that are not typically eaten.
- Eating shellfish is a possible route of human exposure because bivalves are eaten without the removal of the gastrointestinal tract. However this exposure is also expected to be very low, e.g. the European Food Safety Authority (EFSA) estimated that consuming 225 grams of mussels with the highest reported amount of microplastics would result in an exposure of about 7 micrograms of plastic.
- Absorption of intact plastic particles from the gut is likely to be very limited (≤0.3 %). In addition, because of the small mass of plastic consumed it is expected that there is unlikely to be significant increases in exposures to environmental chemicals such as PCBs, PAHs or bisphenol A that may adsorb to the plastic surface.
In light of this information, our current view is that plastic contamination of the food chain is unlikely to result in immediate health risks to consumers. This view is supported by EFSA, which considers that while further work is required, it seems unlikely microplastics are harmful to consumers.
FSANZ will continue to maintain a watching brief on this issue and consult with our international counterparts on any new developments.