Mercury in fish available in supermarkets in Illinois: are there regional differences.
Level 4 - case-series / case-control
Cross-sectional comparative sampling study graded by design analogy (non-clinical).
PubMed 16815532 · doi:10.1016/j.scitotenv.2006.04.018
What was done
Total mercury concentrations were measured in six commercial fish species (including salmon, swordfish, orange roughy, walleye, grouper, and three types of canned tuna) purchased from supermarkets in Chicago, Illinois, in 2005. Measured concentrations were compared across fish types and against historical figures from the U.S. Food and Drug Administration (FDA) national database.
What was found
Mercury concentrations differed significantly among fish types, ranging from a mean of 0.03 ppm wet weight for salmon to 1.41 ppm for swordfish. Maximum values exceeded the 1.0 ppm FDA action level for swordfish, orange roughy, and walleye, and all species except salmon had some samples above 0.5 ppm. Among canned tuna varieties, gourmet tuna had the lowest mercury concentration and white tuna had the highest. Chicago swordfish averaged higher methylmercury levels than the FDA national database (1.26 vs. 0.97 ppm), whereas FDA data reported higher mean levels for grouper and higher maximum levels for tuna steaks. The FDA database lacked data on walleye and gourmet tuna.
Why it matters
National aggregate contaminant databases may fail to reflect local supermarket stock variations. Accurate regional data help high-risk consumers, such as pregnant women, make safer choices regarding commercial fish consumption.
Limits
The abstract does not state the total number of fish samples analyzed (n) or the number of retail stores sampled. Findings reflect a single urban market in 2005, which may not represent current supply chains or other geographic regions. Human exposure and biological uptake were not directly assessed.
Cited by
- supports Wild Alaskan salmon has among the lowest mercury contamination levels of seafood.