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Because shellfish are filter feeders, they can readily accumulate substances from the water column. The types of poisonous or deleterious substances that have been recovered from shellfish include heavy metals, pesticides, petroleum products, polychlorinated biphenyls, and naturally occurring marine biotoxins. The source of these contaminants may be industrial, agricultural, mining, spillage, sewage, dredging operations, sludge dumps, and naturally occurring toxigenic marine organisms.
The FDA has established action levels, tolerances and guidance levels for poisonous or deleterious substances to control the levels of contaminants in human food including seafood (FDA Federal Register, 1977; FDA, 1985). Action levels are established and revised according to criteria specified in the Code of Federal Regulations (21 CFR 109 and 509), and are revoked when a regulation establishing a tolerance for the same substance and use becomes effective. Action levels and tolerance represent limits at or above which FDA will take legal action to remove adulterated products, including shellfish, from the market. Action levels and tolerances, are established based on the unavoidability of the poisonous or deleterious substance and do not represent permissible levels of contamination where it is avoidable. Guidance levels are used to assess the public health impact of the specified contaminant.
Table 1 lists action levels, tolerances and guidance levels established by the FDA for poisonous or deleterious substances in seafood including shellfish. Notices are published in the Federal Register as new action levels are established or as existing action levels are revised or revoked. Should any of these notices affect Table 1, FDA will issue an interpretation advising NSSP participants of this revision or addition.
Class of Substance | Substance | Level | Food Commoditya | Reference |
---|---|---|---|---|
Deleterious Substance |
Aldrin/Dieldrinc | 0.3 ppm | All Fish | CPG sec 575.100b |
Chlordane | 0.3 ppm | All Fish | CPG sec 575.100b | |
Chlordeconed | 0.3 ppm | All Fish | CPG sec 575.100b | |
0.4 ppm | Crabmeat | CPG sec 575.100b | ||
DDT, DDE, TDEe | 5.0 ppm | All Fish | CPG sec 575.100b | |
Diquatg | 0.1 ppm | All Fish | 40 CFR 180.226 | |
Glyphosateg | 0.25 ppm | Fin Fish | 40 CFR 180.364 | |
3.0 ppm | Shellfish | 40 CFR 180.364 | ||
Toxic Elements | ||||
Arsenic | 76 ppm | Crustacea | FDA Guidance Document | |
86 ppm | Molluscan Shellfish | FDA Guidance Document | ||
Cadmium | 3 ppm | Crustacea | FDA Guidance Document | |
4 ppm | Molluscan Shellfish | FDA Guidance Document | ||
Chromium | 12 ppm | Crustacea | FDA Guidance Document | |
13 ppm | Molluscan Shellfish | FDA Guidance Document | ||
Lead | 1.5 ppm | Crustacea | FDA Guidance Document | |
1.7 ppm | Molluscan Shellfish | FDA Guidance Document | ||
Nickel | 70 ppm | Crustacea | FDA Guidance Document | |
80 ppm | Molluscan Shellfish | FDA Guidance Document | ||
Methyl Mercury | 1.0 ppm | All Fish | CPG sec 540.600 | |
Heptachlor / Heptachlor Epoxidef | 0.3 ppm | All Fish | CPG sec 575.100 | |
Mirex | 0.1 ppm | All Fish | CPG sec 575.100 | |
Polychlorinated Biphenyls (PCBs)g | 2.0 ppm | All Fish | 21 CFR 109.30 | |
2,4-Dg | 1.0 ppm | All Fish | 40 CFR 180.142 | |
Natural Toxins | ||||
Paralytic Shellfish Poison (PSP) | 80 μg/100g | All Fish | CPG sec 540.250 | |
Neurotoxic Shellfish Poison (NSP) | <20 MU/100 g | Clams, mussels, Oysters, fresh frozen or canned | NSSP MO | |
Amnesic Shellfish Poison (ASP) | 20 ppm | All Fish (except in the viscera of Dungeness crab where 30 ppm is permitted |
Compliance Program 7303.842 |
Note: the term "fish" refers to fresh or saltwater fin fish, crustaceans, other forms of aquatic animal life other than birds or mammals and all mollusks as defined in 21 CFR 123.3(d).