Chemicals in Fish

How do chemicals get in fish we eat?

  • Harmful chemicals enter the environment through emissions, spills, and improper disposal.  Chemicals on land and in air can wash into waterways—lakes, rivers, streams, bays, and the ocean.
  • Fish can take in these chemicals from the food they eat.  People can take in these chemicals when they eat contaminated fish.
    • The levels of chemicals in fish vary from low to high depending on the type of fish and where it lives.
    • States, tribes, and local governments have issued advisories across the U.S. for eating fish that may be contaminated.
    • The most common chemicals in fish in California are mercury and PCBs, and sometimes DDTs and dieldrin.
Mercury is a natural element in some rock and soil. 
Methylmercury, a more toxic form of mercury, is found in many fish around the globe.

Information on mercury:

For more detailed information on mercury:

Methylmercury in Sport Fish: Information for Fish Consumers (Available as a pdf)

PCBs, a group of man-made chemicals banned in 1979, last a long time in the environment and build up in fish.

Information on PCBs:

DDTs and dieldrin, long-banned pesticides, are found at levels of concern in fish from only a few places in California.

Information on DDTs and dieldrin:

Other Chemicals Now Being Tested in Fish

“PBDEs” (polybrominated diphenyl ethers) are a type of flame retardant.

  • Since the 1970s, they have been used in many consumer goods such as couches, mattresses, carpet padding, clothing, televisions, computers, cell phones, car seats, stereos, and dashboards.
  • During the last 10 years, scientists realized that PBDEs were increasing in the environment—and in people.  The use of most PBDEs has since been banned or is being voluntarily stopped in many areas, including California.
  • Testing fish in California for PBDEs is fairly new but, so far, no fish have been found with levels of concern.

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