Target Contaminants
The selection of appropriate target contaminants in fish and shellfish contaminant monitoring programs is essential for the adequate protection of the health of fish and shellfish consumers. Selecting the target contaminants should be made at the same time as selecting the sampling sites and the target species. The U.S. Environmental Protection Agency has established two lists of contaminants that advisory programs should consider monitoring in fish and shellfish. Both lists contain substances that have been found to occur in the edible tissue of fish and shellfish at concentrations that may be of concern for human health.
Contaminants to Monitor
Table 1 lists contaminants for which the EPA or other federal agencies have released measures of oral toxicity in humans (e.g., reference dose or cancer slope factor). The EPA recommends that fish and shellfish advisory programs use this list for monitoring and issuing advisories with consumption limits.
| Group | Analyte | ||
|---|---|---|---|
| PFAS |
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| Cyanotoxins |
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| Flame retardants |
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| Pharmaceuticals |
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| Metals |
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| Organochlorine pesticides |
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| Organophosphate pesticides |
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| Chlorophenoxy herbicides |
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| Polycyclic aromatic hydrocarbons (PAHs) |
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| Polychlorinated biphenyls (PCBs) |
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| Dioxins |
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| Furans |
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Contaminants to Monitor to Watch
Table 2 lists nine contaminants (two cyanotoxins and seven PFAS compounds) that the EPA recommends that fish and shellfish advisory programs monitor to determine if they are accumulating in fish in local waters. These compounds were documented in studies as occurring in edible tissue of consumed fish or shellfish species at a concentration that could be of concern for human health. These compounds do not currently have measures of oral toxicity in humans (e.g., reference doses or cancer slope factors) issued by a federal agency. The advisory programs could calculate their own or use another agency’s scientifically based measures of oral toxicity in humans to calculate consumption limits or wait for such values to be released from a federal agency. After relevant toxicity values are developed for any of these contaminants, advisory programs should evaluate the concentrations they have found in local fish and shellfish to determine if they need to issue consumption advisories.
| Group | Analyte |
|---|---|
| Cyanotoxins |
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| PFAS |
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These lists of contaminants are not intended to be all-encompassing. Any time a fish and shellfish advisory program deems a contaminant is a public health concern (e.g., there is a spill or known discharge source, or it is found in high enough concentrations to potentially affect the health of people eating fish and shellfish), the contaminant(s) should be included in the contaminant monitoring program. In addition, inclusion of a contaminant on these lists is not meant to imply that it is present in all waters nationwide.
The EPA recognizes that measuring all target contaminants in fish and shellfish tissues collected at all monitoring sites is expensive and that cost can be a limiting consideration when designing and implementing monitoring programs. To focus the contaminant target list, consider the contaminants associated with historic land use, current land use (e.g., rural, agricultural, urban, suburban, and industrial), and point and nonpoint pollution sources. Nonpoint source pollution can include mercury, PCBs and PFAS that impact fish and shellfish. Program managers should evaluate existing environmental, pollution and public health data for the area and/or adjacent water bodies before selecting target analytes. If there is no historic data and/or limited information about the waterbody, a pilot study analyzing as many contaminants as possible and a focused list of species and/or locations could narrow the target contaminant list.
Due to their ability to eliminate PAHs from their bodies, fish may show little or no accumulation of PAHs while bivalve molluscs and crustaceans can be heavily contaminated in PAH-contaminated waters. (Varanasi et al., 1985)
Chemical profiles can be found in IRIS (Integrated Risk Information System) and CompTox Chemical Dashboard.
Methods for analyzing the contaminants are listed in Sample Analysis. The EPA released a fact sheet about the contaminants when they were updated in 2024 and a corresponding document explaining the process.