Mercury exposure from domestic and imported estuarine and marine fish in the U.S. seafood market

Abstract

Background: Methylmercury exposure causes a variety of adverse effects on human health. Per capita estimates of mercury exposure are critical for risk assessments and for developing effective risk management strategies.

Objective: This study investigated the impact of natural stochasticity in mercury concentrations among fish and shellfish harvested from the Atlantic Ocean, Pacific Ocean, and foreign shores on estimated mercury exposures.

Methods: Mercury concentrations and seafood consumption are grouped by supply region (Atlantic Ocean, Pacific Ocean, and foreign shores). Distributions of intakes from this study are compared with values obtained using national FDA (Food and Drug Administration) mercury survey data to assess the significance of geographic variability in mercury concentrations on exposure estimates.

Results: Per capita mercury intake rates calculated using FDA mercury data differ significantly from those based on mercury concentration data for each supply area and intakes calculated for the 90th percentile of mercury concentrations.

Conclusions: Differences in reported mercury concentrations can significantly affect per capita mercury intake estimates, pointing to the importance of spatially refined mercury concentration data. This analysis shows that national exposure estimates are most influenced by reported concentrations in imported tuna, swordfish, and shrimp; Pacific pollock; and Atlantic crabs. Collecting additional mercury concentration data for these seafood categories would improve the accuracy of national exposure estimates.

Figure 1

Seafood consumption and total Hg intake from estuarine and marine fish and shellfish in the commercial market. (A) Seafood consumption estimated in this study from NMFS fisheries supply data compared with available data for marine and estuarine fish consumption from CSFII dietary survey data [uncooked weights (U.S. EPA 2002]. (B) Percentage of total Hg intake (product of seafood supply and Hg concentrations) for the top 15 seafood categories; intake is allocated by the source region for each of the fisheries products [Atlantic, Pacific, imported (foreign sources), and high seas landings]. “Salmon” includes both canned and fresh and frozen products; “Anchovies et al.” includes anchovies, herring, shad, and sardines; “Flounders” includes flounder, plaice, and sole; “Haddock et al.” includes haddock, hake, whiting, and monkfish; and “Grouper et al.” includes grouper and seabass (Table 1).

Figure 2

Summary of Hg concentrations (A) and Hg intakes (B) for all estuarine and marine seafood categories in the commercial market compared with FDA concentrations and intakes calculated from FDA data (Table 1). Abbreviations: alb, albacore/white; lt, light. The bottom and top of each box indicate 25th and 75th percentiles, respectively; the line within the box indicates the median; and whiskers indicate minimum and maximum. Outliers (any point falling above the upper quartile minus 1.5 times the interquartile range) are shown above the plots. In (B), intakes calculated from geographically grouped data are denoted “This Study” for mean per capita intakes and “90th percentile” for intakes calculated from the 90th percentile mercury concentrations for each geographic region.