Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Microplastic pollution of our waterways may not just represent a threat to marine ecosystems but also to human health. “It is evident that humans are exposed to…microplastic pollutants in seafood,” which may create a food safety risk. But, is there some seafood less contaminated than others?

The first published study looked at mollusks. Eating an average serving of mussels, you consume around 90 plastic particles, whereas an average serving of oysters may contain only around 50. “As a result, the annual dietary exposure for European shellfish consumers can amount to 11,000 [swallowed] microplastics per year” — though we don’t yet know what kind of risk this would carry. Of course, “due to their “persistent nature, microplastic abundance” is only going to get worse.

“It is inevitable that humans eating seafood will ingest at least some microplastics, particularly [when the entire creature is consumed, such as mussels, oysters, and small fish. So, what, like sardines? We didn’t know… until now. “Contamination with microplastics and mesoplastics,” which are like little pieces of plastic larger than a millimeter. They looked at 20 brands of canned sardines from 13 countries over four continents, and only found plastic particles in about one in five. They suggested the disparity may have been due to improper gutting in the contaminated samples. But in mammals, at least, ingested microplastics can get through the gut wall and circulate throughout the body, and even cross the placental barrier. So, do microplastics actually make it into the muscles of fish, like a fish fillet? Let’s find out.

If you compare the level of microplastics in eviscerated flesh versus the organs, surprisingly, sometimes the flesh actually contained higher microplastic loads than the excised organs, which highlights that evisceration does not necessarily eliminate the risk of microplastic intake by consumers. Microplastics of all “colors, shapes, and sizes were detected in all investigated fish muscle samples.” So, they do actually get into the flesh. So, the average intake of microplastics from eating flathead, grouper, shrimp, scad, or barracuda may be in the hundreds per 300 gram serving, or just in the dozens of plastic particles in a two-ounce child serving. Besides the plastic itself, the particles may release absorbed pollutants like PCBs, and also release plastics chemical additives like BPA, which collectively may cause hormone disruption, cancer risk, and DNA damage. “Hence, although there is no standard tolerable dose for [microplastics] ingestion as well as information on exact toxicity of different plastic types in the human body, taking…weekly [servings] of these kinds of fish [may] threaten the health of consumers (especially vulnerable groups including pregnant and breastfeeding women and children).”

In the US, “anthropogenic debris,” meaning man-made materials, were found in a quarter of individual fish and in two-thirds of all fish species tested, and also about a third of individual shellfish samples, demonstrating that “man-made debris has infiltrated” the aquatic food chain “up to the level of humans via seafood. Because [this] debris is associated with a cocktail of… pollutants,…this…[validates the] concern that the “debris may be transferring [these chemicals] to humans via diets containing fish or shellfish, raising important questions regarding the bioaccumulation and biomagnification of chemicals, and consequences for human health.” Now, this study also included non-plastic debris, like foams, film, and fibers, but we know now that the ingestion of microplastics “appears to be a widespread and pervasive phenomenon” across a number of commercially important mollusks, crustaceans, and fish.

So: “The potential for humans, as top predators, to consume microplastics as contaminants in seafood is very real, and its implications for health need to be considered… Despite the existence of considerable uncertainties and unknowns, there [may already be] a compelling case for urgent actions to identify, control, and, where possible, eliminate key sources of microplastics before they [ever make it to our oceans.]”

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