Plastic trash is an increasing but preventable hazard to fish health

By Sarah Wheeler

Look around you. How many plastic items are within your arms reach?

There is no question that it is virtually impossible to avoid plastic. It wraps our food, transports our water, and is the building block of countless products. But, less than half of produced plastic ends up in landfills, and alarming amounts litter the environment. Plastic debris ends up our beaches, in the deep sea, miles offshore and in the guts of animals. It is now known that chemicals from plastics are entering the tissues of marine animals and making them sick, as revealed by Dr. Chelsea Rochman at the University of California, Davis.

Plastic Beach

Rochman has discovered that the chemicals in plastic and on plastic transfer into tissues and make fish sick.

The ingredients that make up more than 50% of plastics are already deemed chemical hazards by the UN Globally Harmonized System. But as floating bits of trash, plastics pick up additional pollutants like pesticides, flame retardants and combusted oil. “We don’t know yet how long it takes plastic to fully break down, but it’s somewhere on the order of tens to thousands of years,” says Rochman. This means that plastic debris accumulates a multitude of toxic chemicals over potentially many, many years. This type of marine plastic is ending up as lunch for birds, fish and other animals.

Using fish called the Japanese medaka, Rochman measured the health consequences of a diet supplemented with clean plastic particles as well as plastic with accumulated pollutants from the marine environment. Fish were fed a diet enriched in ‘clean’ plastic, ‘marine’ plastic, or a non-enriched control. After two months, the tissue of fish fed ‘marine’ plastic had higher levels of the chemical ingredients of plastic (PAHs), pollutants known to stick to plastic (PCBs), and additives to plastics (PBDEs). These results reveal that both the chemicals in plastic and on plastic accumulate in fish. This study was the first to show that plastic debris functions as a pathway for toxic chemicals to enter aquatic animal tissue.

Japanese medaka were fed different diets to determine the effect of plastic pollution on fish health. This picture depicts the genetic plasticity of this species and why it serves as a good study organism.

A plastic diet also caused fish to suffer from liver stress, with higher rates of fat deposits and depleted energy stores. In a few cases, fish livers showed signs of cell death and tumor growth.

What is revealing is that these harmful effects were found at concentrations lower than what has been measured in the infamous Great Pacific Garbage Patch, a vast accumulation of marine debris in the middle of the Pacific. These findings suggest that wild fish may already be suffering from health effects incurred from eating plastic.

Image of liver removed from a Japanese medaka fed plastics with absorbed toxins. Circled in black is a tumor that developed during the experiment (see light pink coloration). Image via Scientific Reports/Rochman et. al.
Image of liver removed from a Japanese medaka fed plastics with absorbed toxins. Circled in black is a tumor that developed during the experiment (see light pink coloration). Image via Scientific Reports/Rochman et. al.

Maybe of more concern, are the unknown health effects to humans that consume fish with accumulated toxic chemicals.
Rochman first saw the need to study plastic pollution in 2006 when she found trash where you would least expect it, on isolated islands off of Australia. Since then, she has personally traveled to the most remote locations in the North Pacific and South Atlantic to figure out just how much plastic is out there. When she is not working at sea or in the lab, Rochman is partnering with policy makers at the Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration to find practical and preventative solutions to plastic pollution.

The current “policies for managing plastic debris are outdated and threaten the health of people and wildlife,” Rochman says. There are no requirements for plastic producers to prove that their plastic products are safe, unlike food or pharmaceutical companies.

In a recent comment to Nature, Rochman explains how changing the label of plastic marine debris from “solid waste” to “hazardous substance” will enact policies to manage plastics and plastic pollution in the United States. This label would permit the EPA to clean affected habitats under the 1980 Comprehensive Environmental Response, Compensation and Liability Act.

Infographic via Nature/Rochman, Browne et al. 2013
Nature/Rochman, Browne et al. 2013

Rochman believes that this policy may cause a chain reaction to help government mitigate already contaminated areas and motivate researchers to develop plastics that are safer by design. Apple Inc. has already taken the lead by redesigning their products so that they do not use hazardous plastic materials.

The function of plastic does not have to change, but we certainly can reinvent the ingredients to make them safe for humans and animals in the long term. Take another look around you. Imagine the alternative possibilities for the plastics within your reach.

Be sure to follow The Fisheries Blog on Facebook and Twitter (@FisheriesBlog).

1. Rochman, C., et al. 2013. Ingested plastic transfers hazardous chemicals to fish and induces hepatic stress. Scientific Reports 3: 3263
2. Rochman, C., Browne, A. et al. 2013. Comment: Classify plastic waste as hazardous. Nature 494: 169-171


Sarah Wheeler, Ecology Ph.D. Candidate at San Diego State University and the University of California, Davis

Questions? Contact Sarah at or through her website,

One Comment Add yours

  1. But plastic hazards come in another shape and form: microbeads. They are microscopic “harmless” spheres of plastic mixed with (mostly women’s) cosmetics that are e.g. used for exfoliation (though I believe you can achieve the same cheaper with a stiff towel) in skin care products and cannot be captured by the usual sewage systems. Eventually they flow out into the sea and are ingested by organisms big and small, and even get back into our food chain. However, they increase disease levels and lower vitality and decrease fertility. There’s more than meets the eye and these recent suggestions for wind- or solar-driven boats collection refuse in the oceans won’t catch these microbeads either.

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