In a laboratory at Columbia University’s Lamont-Doherty Earth Observatory, in Palisades, New York, Debra Lee Magadini positions a slide under a microscope and flicks on an ultraviolet light. Scrutinizing the liquefied digestive tract of a shrimp she bought at a fish market, she makes a tsk-ing sound. After examining every millimeter of the slide, she blurts, “This shrimp is fiber city!” Inside its gut, seven squiggles of plastic, dyed with Nile red stain, fluoresce.
All over the world, researchers like Magadini are staring through microscopes at tiny pieces of plastic—fibers, fragments, or microbeads—that have made their way into marine and freshwater species, both wild caught and farmed. Scientists have found microplastics in 114 aquatic species, and more than half of those end up on our dinner plates. Now they are trying to determine what that means for human health.
So far science lacks evidence that microplastics—pieces smaller than one-fifth of an inch—are affecting fish at the population level. Our food supply doesn’t seem to be under threat—at least as far as we know. But enough research has been done now to show that the fish and shellfish we enjoy are suffering from the omnipresence of this plastic. Every year five million to 14 million tons flow into our oceans from coastal areas. Sunlight, wind, waves, and heat break down that material into smaller bits that look—to plankton, bivalves, fish, and even whales—a lot like food.