Legacy Pesticides in Fish and Shellfish

What are legacy pesticides?

  • Legacy pesticides were once widely used in agriculture and home pest control.Tractor on a field spraying pesticide
  • Today, legacy pesticides are banned in the United States due to their harmful effects (though they may still be used in other countries).
  • However, legacy pesticides persist in the environment, and can accumulate in fish and shellfish.
  • Legacy pesticides include chemicals like DDT (dichlorodiphenyltrichloroethane) and related compounds, dieldrin, chlordane, and toxaphene.
  • Only a few California water bodies have fish with significant levels of these chemicals.


What is the health concern for humans?

  • High levels of legacy pesticides may:
    • affect the developing fetus, possibly leading to later changes in learning and behavior.
    • have effects on reproduction, such as decreased fertility.
    • increase cancer risk.
  • Women can pass legacy pesticides on to their babies when pregnant and breastfeeding.


Should I still eat fish?

  • Yes!  Low-contaminant fish are an important part of a healthy, well-balanced diet.
  • Fish are a good source of protein, vitamins, and heart-healthy omega-3 fatty acids. 
  • Eating two servings of fish per week is good for you, according to the American Heart Association.
  • If you are pregnant, eating low-contaminant fish may help your baby’s brain develop.


If legacy pesticides are present, which fish pose the greatest risk?

  • Fatty fish, bottom feeders, and fish that eat other fish. 
  • Larger and older fish.


How can I reduce my risk?

  • If you catch your own fish, follow the Office of Environmental Health Hazard Assessment’s (OEHHA) fish advisories for California water bodies.
  • Keep in mind that legacy pesticides accumulate in the skin, fat, and some internal organs of fish or shellfish.
  • Trim the fat, remove the skin, and fillet the fish before cooking.  Eat only the skinless fillet (meat).
  • For crab and lobster, remove the internal organs (“guts,” “butter,” or “tomalley”) and rinse out the body cavity before cooking.
  • Bake or grill fish in a way that lets the juices drain away.  Throw away the cooking juices.
  • Boil or steam crab and lobster, and discard the cooking liquid.
  • Do not use the fat, skin, organs, juices, or the whole fish or shellfish, in soups and stews.

Diagram for how to prepare fish by removing skin, fat, and guts

Where can I learn more?

Fish Advisory Map

View maps of current statewide and site-specific advisories

Advisory Map

Fish, Ecotoxicology and Water Section

Sacramento Office
1001 I Street
Sacramento, CA 95814
Phone: (916) 423-7572

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