A Quantitative Synthesis of Mercury in Commercial Seafood and Implications

Overview

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Key numbers

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• Results: Mean Hg concentrations for each seafood item were highly variable among studies, span‑ 2006) but typically are not integrated into
• ning 0.3–2.4 orders of magnitude. Farmed fish generally had lower grand mean Hg concentrations larger analyses of exposure and risk. Finally,
• tions for public health and the formulation of consumption guidelines. Exposure and risk analyses 2010). Imports now account for > 80% of
• exposure estimates (Ginsberg and Toal 2009; Search Terms for Table S2 (http://dx.doi. of market size (vs. juvenile fish from hatch-
• in Hg and/or they constitute relatively large were included only if at least 5% of all imports fisheries closures.
• Department of Environmental Quality (2009); because the commercial catch of salmon from Hg concentrations in a graph or as a range,
• et al. 2009). of the distribution under­lying the grand mean sizes for the comparisons of interest, made
• / w i _Hg i - Hg w i2 tion exceeding the FDA action level (1 ppm)
• Approximately 40% of the included sources SE w = N , (2) and the U.S. EPA human health criterion
• reported SDs or SEs. Thus, analyses requir- ^N - 1 h / w i (0.3 ppm) for seafood items with relatively
• of including the range of Hg concentrations where N is the number of studies from which action level for MeHg of 1.0 ppm represents
• ues when they were reported instead of total age sample size across studies for each seafood MeHg criterion of 0.3 ppm represents the
• Hg. Approximately 95% of total Hg in fish item, yielding the formula fish tissue concentration that should not be
• content, if reported, or by assuming 80% log­n ormal distributions, where w i ranged and brown bullhead, whereas farmed catfish
• water content. When Hg concentrations were from 2 to 100 and N ranged from 50 to 300. include channel catfish and striped catfish.
• reported as non­detects (approximately < 10% Tests of 10,000 replicates demonstrated that We designated individual data as farmed or
• When a study reported multiple mean Hg (data not shown). statistics for individual species (FAO 2011).
• 1978), we calculated a weighted mean using SD, c) range (minimum and maximum wild-caught and rainbow trout were farmed.
• /^Hg i # w i h parisons were possible given available data Material, Table S1 (Summary of Hg concentra-
• where Hgi is the ith reported mean and wi is food categories, which often included mul- Hg Database) (http://dx.doi.org/10.1289/
• any further updates are also available from in major regions in the world (excluding orange roughy (0.513 ppm; 152 samples)
• Coastal Assessment)), the Seafood Hg Database 60% of seafood imported into the United Lange et al. 1993).
• includes data from both academic and govern­ States is from Asia, but only 16% of non-U.S. Comparison with FDA‑MP and federal
• ment data sources (approximately 50% of studies were conducted in Asia. The most stud- criteria. Mean Hg concentrations from the
• amounts of data on imported fish and shellfish high-Hg items (0.6 to ≥ 1 ppm) such as shark from the Seafood Hg Database by ≥ 20%
• (43% of observa­tions, 21% excluding market (grand mean Hg, 0.882 ppm; 3,722 samples) for more than half (33 of 58) of the seafood
• studies outside of the United States for which as well as moderate-Hg items (0.3–0.59 ppm) items listed in the summarized FDA‑MP
• exact seafood origin is uncertain). such as tuna (0.450 ppm; 3,780 samples) and data (Figure 3). Most of these discrepancies
• Variability, patterns, and information low-Hg items (0–0.29 ppm) such as oysters were cases in which the FDA‑MP estimates
• gaps. We observed relatively high variability (0.020 ppm; 5,310 samples) (see Supplemental for mean Hg content were lower than grand
• in Hg concentrations for individual seafood Material, Table S1 (http://dx.doi.org/10.1289/ mean estimates from our database (27 of
• items. Mean Hg concentrations reported ehp.1205122)). The least studied items 33 seafood items; Figure 3B). Of these, only
• across studies for a given seafood item spanned included monkfish (0.174 ppm; 92 samples) marlin, king mackerel, and weakfish/seatrout
• 0.3 to 2.4 orders of magnitude (for tilefish and haddock (0.164 ppm; 226 samples) and fresh­w ater trout were moderate‑ to
• frozen, respectively), with a mean of 1.3 orders tilefish (all, 0.883 ppm; 109 samples) and estimates of mean Hg content were higher
• tions for farmed counter­parts. For example, Figure 1. Grand mean Hg ± SE in farmed and wild seafood items by category.
• mean Hg for wild catfish was 12 times higher
• than mean Hg for farmed catfish. Both wild 70
• mum mean Hg concentrations (e.g., 0.005 and 60
• see Supplemental Material, Table S1 (http:// 50
• Material, Table S1). Asia North America South America Europe Oceania Africa
• than our grand mean for only 6 seafood items Discussion were cases in which the FDA‑MP estimates

Methods (brief)

• Objectives: We examined patterns, variability, and knowledge gaps of Hg in common commercial tains smaller sample sizes and fewer species.
• those used for exposure estimates and consumption advice. studies that focus on obtaining large sample
• individual studies, weighted by sample size. We also compared database results to those of federal Such smaller, intensive studies are common
• graphic regions for which further study is most Reuters, New York, NY) before 15 December and perch, we included fish collected from
• trations in their wild seafood counter­parts. varieties listed as the top 51 Hg contributors excluding samples from interior or landlocked
• Hg levels for seafood items considered the top for a given fish or shellfish species collected calculations.
• our database does not model the exact com- if the samples were collected from water bodies to be lower in small fish than in larger fish
• scientific literature. We obtained data from collected from domestic waters, we included porated into government monitoring efforts.
• results publically available online (e.g., State to the market (NMFS 2011c). We did not MeHg concentration and sample size). For
• • Data from areas with no commercial fishing By definition, the SD of sample means is the aggregate mean Hg values instead of raw data.
• national parks (e.g., Rencz et al. 2003; Wyn Therefore we estimated the weighted SE (SEw) lying Hg data, together with unequal sample
• weight), sample size, and geographic location of studies reporting a mean Hg concentra-
• for each seafood item using the largest pos- mean Hg values were collected. To obtain the the threshold above which the agency can take
• ues when they were reported instead of total age sample size across studies for each seafood MeHg criterion of 0.3 ppm represents the
• not reported, these values were excluded. distribution used and variation in sample size we made assumptions based on FAO fisheries
• sample size for the mean as the weight. When reported means), d) coefficient of variation For eel species from market studies, we
• a study reported multiple Hg values for a given (CV), and e) total number of samples across assumed that Japanese eel (Anguilla japonica)
• seafood item but did not provide sample sizes all studies for each seafood item name searched were farmed and European conger eel were

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

Wiki pages this source may touch

• Fish — marine, predatory (tuna, swordfish, shark, king mackerel)
• Fish — marine, non-predatory (sardines, anchovies, salmon, cod)
• Shellfish (shrimp, crab, lobster, clams, oysters, mussels)
• Mercury
• Mercury

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Update history

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