If you like eating seafood or salt, what you might not know is that you’re ingesting something extra along with that shrimp and seasoning—microscopic bits of plastic known as microplastics. Created by the breakdown of plastic bags and other refuse in our oceans, microplastics saturate seawater. There are at least five trillion pieces of these bad boys in the oceans today, ready to be ingested by those oysters that might end up on your plate at happy hour, or dried into the flaky sea salt that graces your seared steak.
Over the past couple of years, a spate of studies demonstrating the ubiquity of microplastics in our food supply have, understandably, provoked concern among diners. The idea of unwittingly ingesting appreciable amounts of plastic is obviously distasteful, and several papers have explored the possible negative health effects of these ingested plastics, which can remain in our bodies and might disrupt our endocrine systems.
But a leading researcher in the field of microplastics cautions that these tiny particles might be the least of our worries when it comes to our exposure to plastics. Nanna B. Hartmann, a senior researcher at the Technical University of Denmark, wrote her PhD on the ecotoxicology of microplastics, and has continued to focus her research on these insidious bits. Earlier this year, she and three of her colleagues published a paper in which they argue that research on microplastics is in its infancy, and that more studies on the particles’ health effects are needed before we throw up our hands in defeat and swear off seafood. We live in such an incredibly plastic-polluted world, the authors write, that our exposure to microplastics through our food and drink is probably minimal, whereas habits like ubiquitous Ziploc bag use and Saran wrapped-everything are surefire ways to ingest chemicals. We talked with Hartmann about the paper and why she thinks we can keep eating shrimp scampi—for now.
MUNCHIES: Hi, Nanna. Can you explain what microplastics are? How big of a threat do you think they represent to human health?
Nanna B. Hartmann: Microplastics are very small (i.e. micrometer to millimeter size range) pieces of plastics that are either produced intentionally (for example for use in cosmetics) or are generated through the degradation or abrasion of larger plastic items. This is the case, for example, with a plastic bag, which ends up in the environment (e.g. in the ocean) due to improper handling of waste, where it slowly degrades, releasing small plastic particles.
A few studies have found effects of microplastics at environmentally relevant concentrations. Other studies see no or minor ecotoxicological effects. When it comes to human health, very little is currently known about the effects of microplastics. We need, as a first step, to generate more information on what and how much we are actually exposed to.
In your article, you say that " the problem is that the debate on microplastics lacks perspective." Can you explain this statement?
What we mean is that, when new results come out and appear in the media, there is a tendency to focus on very specific cases. For example, in light of studies coming out last year, there was suddenly a lot of attention on microplastics in tap water. Aside from the fact that the sampling and analytical methods used may not have been the best, this very focused debate on microplastics from one single source does not correspond well with our overall exposure to microplastics from our surroundings.
If you leave a cup of coffee on the table for 10 minutes, it is likely that some microplastics from the air will end up in your cup—simply because we are surrounded by plastic materials in our everyday life. For example, a fleece sweater will release small plastic fibres.
We're exposed to lots of plastic in food packaging, water bottles, and more. Do you think those sources should be of more concern to us than microplastics?
I think that all uses of plastics should be considered in relation to their role as a potential source of microplastics, as well as their contribution to human exposure to plastic-related chemicals. For plastic-related chemicals, their release from larger plastic items—such as food packaging and water bottles—is likely of higher concern than the contribution from microplastics.
If we're focusing too much on microplastics, then what areas of our consumption should we be more concerned about? Are there more important issues to pay attention to?
Our point is not that we should not focus on microplastics. We simply argue that we need to consider the relative importance of different exposure pathways instead of ‘getting lost’ in individual findings. When communicating our findings as scientists, we need to maintain a broad perspective. And of course, when discussing how to reduce human exposure to microplastics and plastic-related chemicals, we need to have a broader debate on global plastic production and usage.