As plastic waste increases rapidly around the world, an essential question remains unanswered: What harm, if any, does it cause to human health?
A few years ago, as microplastics began turning up in the organs of fish and shellfish, the concern was focused on the safety of seafood. Shellfish were a particular worry, because in their case, unlike fish, we eat the entire animal — stomach, microplastics and all. In 2017, Belgian scientists announced that seafood lovers could consume up to 11,000 plastic particles (粒子) a year by eating mussels (贻贝), a favorite dish in that country.
By then, however, scientists already understood that plastics continuously fragment small pieces in the environment, tearing over time into fibers even smaller than a strand of human hair — particles are so small that they easily fly in the air. A team at the U.K.'s University of Plymouth decided to compare the threat from eating polluted wild mussels in Scotland to that of breathing air in a typical home. Their conclusion: People will take in more plastic by breathing in or taking tiny, invisible plastic fibers floating in the air around them—fibers from their own clothes, carpets, and soft covering on furniture — than they will by eating the mussels.
So, it wasn't much of a surprise when, in 2022, scientists from the Netherlands and the U.K, announced they had found tiny plastic particles in living humans, in two places where they hadn't been seen before: deep inside the lungs of surgical patients, and in the blood of unknown donors. Neither of the two studies answered the question of possible harm. But together they signaled a shift in the focus of concern about plastics toward the cloud of dust particles in the air, some of them are so small that they can get into deep inside the body and even inside cells, in ways that larger microplastics can't
Dick Vethaak, a professor of ecotoxicology (生态毒理学), doesn't consider the results alarming, exactly—"but, yes, we should be concerned. Plastics should not be in your blood." "We live in a multi-particle world," he adds, referring to the dust, pollen (花粉), and smog that humans also breathe in every day. "The trick is to figure out how much plastics contribute to that particle burden and what does that mean."