Overview
Lorenzana, Yeow, Colman, Chappell, and Choudhury reviewed arsenic speciation evidence for seafood risk assessment, focusing on the fraction of total arsenic present as inorganic arsenic. The paper is a literature survey and does not contribute a single new sampling campaign. Its main contribution is context for keeping measured total arsenic separate from inorganic arsenic in seafood, shellfish, freshwater fish, and seaweed.
Key numbers
The abstract reports that, in worldwide literature, percent inorganic arsenic in marine/estuarine finfish did not exceed 7.3% and in shellfish reached 25% in organisms from presumably uncontaminated areas. It also states that percentages can be much higher in organisms from contaminated areas and in seaweed, and that U.S. freshwater finfish site-assessment data generally averaged below 10% but ranged up to nearly 30%.
Table 2 summarizes worldwide seafood literature outside the United States:
| Seafood group | Basis / context | Total arsenic | Inorganic arsenic | Percent inorganic / total |
|---|---|---|---|---|
| Marine/estuarine finfish | dry weight basis | 0.62-74.96 mg As/kg tissue | 0.0028-0.78 mg As/kg tissue | 0.02-6.88 |
| Marine/estuarine finfish | wet weight basis | 0.728-31.7 mg As/kg tissue | 0.003-0.49 mg As/kg tissue | 0.09-7.31 |
| Marine/estuarine finfish | wet weight, mine-tailings contaminated area | 0.18-2.24 mg As/kg tissue | 0.01-0.21 mg As/kg tissue | 1.31-12.2; 4.4 based on mean values |
| Shellfish | dry weight basis | 0.68-118 mg As/kg tissue | 0.02-3.8 mg As/kg tissue | 0.07-25.3 |
| Shellfish | wet weight basis | 0.81-67.9 mg As/kg tissue | 0.001-2.43 mg As/kg tissue | 0.02-6.55 |
| Shellfish, Barnea dilatata | wet weight, Japanese market outlier | 0.200 mg As/kg tissue | 0.193 mg As/kg tissue | 95 |
| Shellfish | wet weight, mine-tailings contaminated area | 0.8-228 mg As/kg tissue | 0.02-81 mg As/kg tissue | 0.35-48.6 |
| Seaweed | dry weight basis | 0.145-149 mg As/kg tissue | 0.019-117 mg As/kg tissue | 0.2-80 |
| Seaweed | wet weight, mine-tailings contaminated area | 26.5-33.5 mg As/kg tissue | 9.4-13.2 mg As/kg tissue | 28.1-49.8 |
Table 3 summarizes U.S. site-assessment data from presumed or known contaminated areas:
| Seafood group | Basis / context | Total arsenic | Inorganic arsenic | Percent inorganic / total |
|---|---|---|---|---|
| Marine/estuarine finfish | dry weight, Asarco Tacoma Smelter | 18.8-62.7 mg As/kg tissue | 0.01-0.06 mg As/kg tissue | 0.01-0.04 |
| Marine/estuarine finfish | wet weight, Asarco Tacoma Smelter | 0.53 mg As/kg tissue | 0.01 mg As/kg tissue | 1.9 |
| Shellfish | dry weight, Asarco Tacoma Smelter | 7.18-40.6 mg As/kg tissue | 0.01-0.05 mg As/kg tissue | 0.02-0.7 |
| Shellfish | dry weight, South Carolina coast | 33-46 mg As/kg tissue | 4.9-9.8 mg As/kg tissue | 20-30 |
| Shellfish | wet weight, Puget Sound / Marrowstone Island / Asarco Tacoma | 0.761-4.2 mg As/kg tissue | 0.004-0.36 mg As/kg tissue | 0.4-13.7 |
| Freshwater finfish in brackish lake | wet weight, Salton Sea | 1.06-4.61 mg As/kg tissue | 0.02-0.011 mg As/kg tissue | 0.07-0.85 |
| Freshwater and anadromous/migratory finfish living in freshwater | wet weight, Lower Columbia / Willamette | 0.098-1.79 mg As/kg tissue | 0.001-0.047 mg As/kg tissue | 0.1-26.6 |
The conclusion states that nationwide default values or generalizable values for percent inorganic arsenic in finfish, shellfish, or seaweed/algae potentially contaminated by arsenic at U.S. hazardous waste sites are not supported by the available published data.
Methods (brief)
The authors surveyed journal articles and USEPA documents that reported arsenic speciation in seafood. The review focused on studies reporting detectable concentrations of both total arsenic and inorganic arsenic in tissues of marine and freshwater finfish, shellfish, and seaweed consumed by humans. The authors did not convert dry-weight and wet-weight results to a common basis because tissue water content was often unavailable and variable; they also excluded non-detect inorganic arsenic results from the main summary tables.
Implications
This review supports seafood evidence routing as speciation context rather than as a primary occurrence dataset. It is useful for documenting why total arsenic cannot be silently treated as inorganic arsenic in fish, shellfish, or seaweed, and why literature-default inorganic arsenic (iAs) fractions are weak for contaminated-site assessments. Downstream occurrence pooling should use primary studies from the review when available, not this review table as a substitute for sample-level data.
Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git.
| Commit | Date | Change | Description |
|---|---|---|---|
| b01ec52c31 | 2026-08-04 | major | 1 section added |
| 3171d069e3 | 2026-08-02 | major | 1 section added |
| 90a2f9a38e | 2026-07-30 | major | 1 section added and 1 removed |
| eaa8eeeedf | 2026-07-27 | major | 1 section added and 1 removed |
| aca5e2155a | 2026-06-09 | major | 1 section added |