Think about all the plastic items you use each day – detergent jugs, prescription vials, water bottles, food containers, grocery bags. Now, add in some other products you probably didn’t know contain plastic, things like paper coffee cups and plates, chewing gum, store receipts, cleaning products, paper tea bags and clothing.
These items and many more can release microplastics – tiny plastic particles up to 5 mm in size – into our bodies and the environment whenever they are used. The smaller they get, the more insidious they can be, infiltrating our air, water, soil, food and body tissues without our being the wiser.
Unfortunately, there’s no way of avoiding microplastic exposure in modern societies.. Scientists estimate that each week, an average adult ingests an amount equivalent to a credit card. Research suggests these substances may be linked to cancer, heart attacks, reproductive issues and other significant health risks. And it’s not hard to see why they are bad news for the environment as well.
Recently, a group of experts took part in a National Academies of Sciences, Engineering, and Medicine webinar on the pathways through which these substances enter the body. Bart Koelmans of Wageningen University, Tracey Woodruff of the University of California-San Francisco, Matthew MacLeod of Stockholm University and Jane Muncke of the Food Packaging Forum examined what has been learned about microplastics’ effects on human health.
A growing concern
The panelists explored the range of microplastic bioavailability, from large “macroplastics” like bottles and jars down to synthetic textiles, plastic pellets, material from tires and paint, and some of the smallest particles found in personal care products and other substances. Microplastics have been discovered in many systems and tissues of the body, including saliva, hair, blood, breast milk, kidneys, liver, colon, lungs, placenta, spleen and feces. They can be ingested in food and beverages, inhaled as airborne particles and even absorbed through the skin.
Woodruff explained why the problem of microplastic contamination is likely to grow in the future. Data show that the global production of plastics – which come from fossil fuel-based petrochemicals – has risen steadily over decades, with more than 400 million tons of polymer resins and fibers being manufactured annually by 2019. The most common types of plastic polymers include polyethylene terephthalate (beverage bottles, food containers), high-density polyethylene (toys, cereal box liners), polyvinyl chloride (shrink wrap, flooring materials), low-density polyethylene (garbage bags, juice boxes), polypropylene (carpeting, luggage) and polystyrene (auto parts, styrofoam packaging).
Many plastic particles are so small, they can’t be seen by the human eye, making them more difficult to detect and more capable of entering the body. Woodruff outlined three main categories of particles – macroplastics, which measure 5 millimeters and larger; midrange microplastics, comparable in size to a human hair width or grain of salt; and the very smallest particles, nanoplastics, which can be the size of a smoke particle or the width of a DNA strand. Some of the most significant industry sources of plastic waste are packaging, textiles and consumer and institutional products.
Reducing dependence and exposure
Woodruff noted that microplastics are “persistent and bioaccumulative and only break into smaller particles,” increasing the chances of human exposure over time. Woodruff also pointed out that very young children are at particular risk as they crawl on flooring, touch many objects and surfaces and often put their hands in their mouths. Woodruff said research has demonstrated an urgent need for exposure studies at different stages of human development, tools to allow faster screening, and appropriate policy decisions to mitigate health effects.
Muncke explained how nanoplastics can be generated from the use of everyday materials like food packaging, noting that there are about 1,400 plastic chemicals that can migrate from these materials into food. “If we reduce our dependence on plastic packaging, we can reduce exposure to microplastics and chemicals,” Muncke noted.
MacLeod discussed how microplastics behave in soil and may lead to human exposure. “We should be concerned about this,” MacLeod said. “We have seen how polyfluoroalkyl substances, or PFAS, accumulate in sewage sludge and can make agricultural land irreversibly contaminated. This may also be the case with microplastics. We shouldn’t assume they will not be bioavailable.”
According to Koelmans, researchers are using artificial intelligence platforms to assess the growing volume of microplastics research and the risks the substances pose. “The tools are available for assessment, but the data is often not of perfect quality,” he said. “We have a lot of work yet to do.”
Learn more about microplastics
- The National Academies of Sciences, Engineering and Medicine’s Environmental Health Matters Initiative and the National Oceanic and Atmospheric Administration website. have more information about microplastics.
- Recent news on the subject includes CNN articles on microplastics in saliva and brain tissue, as well as CBS coverage on how to minimize exposure.
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