Cadmium in Fish and Shellfish

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What is cadmium?

• Cadmium (Cd) is a metal found naturally in soil and water (including oceans and freshwater sources).
• Cadmium can also be released into the environment by burning fossil fuels, refining metal ores, soil erosion, mining, industrial discharges, and wastewater processing.
• Cadmium in the air and soil makes its way into rivers, lakes, and oceans through rain and snow runoff.

How does cadmium get into fish and shellfish?

• Cadmium is commonly found in most aquatic environments: it passes into tiny plants and animals that live in water and into the fish and shellfish that eat them.
• Cadmium builds up in the internal organs of fish and shellfish. Bivalve shellfish often have higher levels than those in fish and crustaceans.    

What is the health concern for humans?

• Too much cadmium can:
  • harm the fetus because it can collect in the placenta and interfere with the development and function of the placenta during pregnancy.
  • damage the kidneys of children and adults.
• Women can pass cadmium on to their babies during breastfeeding.

Should I still eat fish and shellfish?

• Yes! Low-contaminant fish and shellfish are an important part of a healthy, well-balanced diet.
• Fish and shellfish are a good source of protein and vitamins, and are a primary source of heart-healthy omega-3 fatty acids.
• Eating two servings of fish or shellfish per week is good for your health, according to the American Heart Association.
• Eating low-contaminant fish and shellfish during pregnancy is beneficial for your baby’s brain development.

Which fish and shellfish have the most cadmium?

• Bivalve shellfish such as clams, mussels, oysters, and scallops usually have the most cadmium in the “edible” tissues.
• Finfish and crustaceans (for example, crab and lobster) usually have less cadmium with most of it stored in the internal organs or “guts” which can be easily removed.

Can I reduce cadmium levels in fish or shellfish to make eating them safer?

• Finfish and crustaceans (for example, crab and lobster): 
  Yes. Cadmium accumulates in the internal organs or “guts”. Remove the internal organs before cooking and eat only the skinless fish fillet. For crustaceans, eat only the body or tail meat.
• Bivalve shellfish (for example, mussels and clams): 
  No. Bivalve shellfish are typically consumed whole so there is no simple way to clean or prepare them that will reduce their cadmium levels.

How can I reduce my risk?

• If you catch your own fish and shellfish, follow the Office of Environmental Health Hazard Assessment’s (OEHHA) fish advisories for California water bodies.
• OEHHA has advice specifically for pregnant women. Cadmium may affect the placenta and harm the fetus.
• OEHHA also has advice for non-pregnant women, men 18 years and older, and children 1 – 17 years old.
• Cadmium can stay in your body for a long time. All people should be careful to eat low-cadmium fish and shellfish.
• Eat only the skinless fillet of finfish and only the body or tail meat of crustaceans.
• Do not use the organs or the whole fish or shellfish in soups and stews.

Where can I learn more?

• OEHHA’s Fish Advisory Program in California
• Cadmium | Biomonitoring California
• ToxFAQs™ - Cadmium (ATSDR)
• Cadmium in Food and Foodwares (USFDA)