Variability of Mercury Concentrations Across Species, Brand,

Overview

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Key numbers

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1 part per million (PPM), a regulatory standard that allows the FDA to take legal action
were purchased in groups of 3 or more (n = 3–44) and analyzed for differences in total Hg
medium (water or oil; Supplemental Table S1). A variety of species were analyzed in this
using a linear equation derived from a calibration curve that ranged from 0.1 to 1000 ng
dilution of a certified HgCl2 standard in 2% HCl (1000 ± 5 µg/mL; lot# 1923928, AGS
defined as LOD = meanblanks + 3 (SDblanks ), was 0.002 ng (n = 27).
were reported, in other words, Hg concentrations below the detection level of 0.01 PPM,
we assigned an interpolated concentration of LOQ/ 2 (Supplemental Tables S2 and S3).
coefficient of variation for all analyzed samples, except for one crab sample, was ≤15%
(Supplemental Table S1). A Shapiro–Wilk test was used to assess the normality of all
Table S4). A significant difference in tHg concentrations was observed across the different
(WW), in (A) albacore tuna (n = 44), light tuna (n = 27), skipjack tuna (n = 11), and yellowfin tuna
(n = 13), (B) anchovies (n = 3), herring (n = 6), mackerel (n = 4), salmon (n = 9), sardines (n = 7), and
trout (n = 3), and (C) clams (n = 3), crab (n = 6), oysters (n = 6), scallops (n = 3), and squid (n = 3);
as reported by Karimi et al., 2012 (22). Graphs indicate mean, min, max.
food analyzed (Supplemental Table S5). Notably, samples of albacore tuna exceeded the
FDA action level of 1 PPM (i.e., 1000 ng/g; 2%), the EPA screening value for recreation of
0.4 PPM (i.e., 400 ng/g; 9%), and the EPA screening value for subsistence of 0.049 PPM
(i.e., 49 ng/g; 100%; Supplemental Table S5). Additionally, samples of light tuna (89%),
skipjack tuna (100%), yellowfin tuna (46%), herring (50%), and crab (83%) exceeded the
EPA screening value for subsistence (Supplemental Table S5).
p = 0.002; η 2 = 0.51, Figure 2A, Supplemental Table S6) and light tuna (F = 4.07; p = 0.01;
η 2 = 0.52; Figure 2B, Supplemental Table S7). Concentrations of tHg in albacore tuna from
reported by the FDA (Supplemental Table S8); however, a significant difference in
these findings largely agree with previous surveys of Hg in fish (Supplemental Tables S8
level of 1.0 PPM, and the EPA has set screening values for fish consumed by recreational
fishers (0.4 PPM) and subsistence fishers (0.049 PPM; Supplemental Table S10). Notably,
one (3%) of our cans of albacore tuna exceeded the FDA action limit, reaching 1.3 PPM, and
four (9%) samples fell above the EPA advisory for recreational fish consumption. Given
of 1 PPM (21). Differences in analysis methods may contribute to discordance in results
//www.mdpi.com/article/10.3390/toxics13060426/s1, Table S1. Total mercury concentration in all
samples analyzed based on wet weight or dry weight. Table S2. Mercury concentrations (PPM) in
Table S3. Mercury concentrations (PPM) in canned albacore tuna from the FDA Mercury Levels in
Commercial Fish and Shellfish study, 1990–2012. Table S4. Total mercury concentrations for each
type of seafood. Table S5. Percent of seafood exceeding FDA action levels and EPA screening levels
for total mercury concentrations. Table S6. Results of univariate general linear model analysis for
weight analysis in albacore tuna. Table S7. Results of univariate general linear model analysis for
weight analysis in light tuna. Table S8. Comparison of Albacore and Light Tuna wet weight results
with the FDA mercury concentrations in fish monitoring program, 1990–20121. Table S9. Mercury
concentrations (PPM) in seafood items from Karimi et al., 2012 (22). Table S10. Minimal risk levels for

Methods (brief)

atomic absorption spectrophotometry. Products were grouped into three categories based
sample from a wide range of brands, in Raleigh, North Carolina, United States. Products
2.2. Sample Preparation
Packages were opened inside a hood, liquid was drained, and a subsample of seafood
Fisher Scientific, Waltham, MA, USA; 15-340-157). Samples were homogenized for 3 min
Fisher Scientific; 15-340-164). After homogenization, samples were briefly centrifuged at
2000 relative centrifugal field (rcf) for 1 min. Each homogenized sample was aliquoted
MO, USA). Tissue was freeze-dried in order to compare samples statistically across brand,
confounding variable. Freeze-dried samples are referenced throughout the paper as dry
3000 mercury analyzer (Nippon Instruments, Osaka, Japan) following guidance outlined
in US EPA methods 7473 and as previously described (30,31). Each experimental sample
was thawed, and approximately 10 mg subsamples were weighed at room temperature
day of analysis, between every 10 samples, as quality control, and the limit of detection,
defined as LOD = meanblanks + 3 (SDblanks ), was 0.002 ng (n = 27).
spectrometry (ICP-MS), was different from the one used in this study. Where non-detects
we assigned an interpolated concentration of LOQ/ 2 (Supplemental Tables S2 and S3).
coefficient of variation for all analyzed samples, except for one crab sample, was ≤15%
would be significantly different across the three broad groups of samples we purchased,

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.

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Verification notes

Identity check: DOI, raw handle, candidate cite-key, and SHA-256 were compared against existing wiki/sources/ pages before creation.
Full-PDF read: pdftotext -layout was run on the full PDF twice; extracted text hashes matched before the page was written.
Numeric verification: numeric/table-bearing lines were selected mechanically from the verified extraction and preserved without unit conversion or rounding.
Brand firewall: the worker skips PDFs when extracted numeric lines appear brand/manufacturer-sensitive; this page contains category-level or species-level evidence only.
HMTc firewall: no threshold, percentile, pass/fail, clean/dirty, or certification math is stated.

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. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised