Fish for dinner? Your seafood might come with a side of plastic

As much as 12.7m metric tons of plastic enter the world’s oceans each year. According to the World Economic Forum, by 2050 there could be more plastic in the sea than fish.

It’s clear that waste ends up in marine habitats from many different sources, from inefficient industrial waste management to plastic microfibers washed out of our clothing. But it’s less clear what the end result might be for human health.

All that plastic isn’t just floating about, breaking down into increasingly microplastic particles and creating an unsightly mess: it’s also getting eaten by marine life.

Fish appear to be “stuffing themselves” on plastic, which is coated in bacteria and algae, mimicking their natural food sources. Mistaking the small particles for a high energy snack, fish gobble up most small plastic particles, according to recent research.

Much of that plastic ends up in the guts of fish and other marine life, and ultimately on our dinner table.

While the actual plastic bits might be in the stomachs of fish, the chemical used to manufacture the plastic “may migrate into fish flesh and thus edible parts of seafood”, explains Rolf Halden, director of Arizona State University’s Center for Environmental Security.

Those chemicals that have “hitched a ride on plastics” may sometimes be found “in accumulated concentrations that may be harmful to humans”, says Halden.

In a study published in 2015, marine researchers bought fish at public markets in California and Indonesia and examined their stomach contents. Around one in four fish at markets in both locations had plastic particles in their guts.

A previous study in 2014 found microplastics in the guts of oysters and mussels sold at supermarkets. In the case of oysters and mussels, people eat the entire organism, including the gut.

Our understanding of what eating plastic-contaminated fish does to a person is still in its infancy.

“We don’t know the effects,” says Chelsea Rochman, Smith Fellow in Conservation Biology at the University of California Davis and lead author of the 2015 study on microplastic contamination in fish.

“Health advisories for seafood consumption already exist for established contaminants such as dioxins, PCBs and mercury,” points out Halden. “Currently there are no similar regulations for plastics and plastic-borne pollutants, as the science is still young.”

While Rochman’s study looked at plastic found in the stomachs of fish, she says the next step would be to look at chemical contamination in the flesh of fish from plastic exposure to measure just how much of it leaches into the flesh of marine creatures.

Fatty tissue is known to store higher concentrations of contaminants, so fattier fish, like salmon and tuna, would be expected to have higher levels of contamination from plastic exposure.

While more research is needed into human impacts, studies have already shown that when it comes to the health of fish, plastic already causes harm. Researchers have found that fish raised in waters rife with microplastics are “smaller, slower, and more stupid” than fish raised in clean water.

There are some mitigation attempts being made to plastic contamination. The US banned the use of microbeads in personal care products last year, a law that won’t take effect until 2017.

The Environmental Protection Agency (EPA) also puts out advisories when some form of chemical contamination that might impact seafood is suspected in US waters. But the majority of seafood eaten in the US is imported and never tested for contamination by the EPA and other government agencies.

While scientists try to pin down the damage plastic pollution is causing to marine life and those that eat it, experts agree on one thing: the amount of plastic that ends up in our waterways must be reduced dramatically.

When it comes to plastic pollution, Halden says: “We can do better.”