Large Predatory Fish

Tuna, swordfish, king mackerel, shark.

37High burden · out of 100

Cleaner swapSmall fish: sardines, anchovies, wild salmon

How this score is built

100Start
72.4Chemical hazard 6 × 4.6−27.6
55.4Everyday exposure 5 × 3.4−17
37Persistence 7 × 2.6−18.2, then rounded to 37
HighThe band37 sits in 20–39.

What each input rests on

The three ratings behind the score, and the studies each rests on
Input	Rating	Evidence
Chemical hazard	6/10	In a Faroe Islands birth cohort of 1,022 children, prenatal methylmercury exposure from the mother's diet was linked at age 7 to poorer language, attention and memory, still seen after excluding children whose mothers had hair mercury above 10 µg/g. Cognitive deficit in 7-year-old children with prenatal exposure to methylmercury · Neurotoxicol Teratol 1997 DOI 10.1016/s0892-0362(97)00097-4 · PMID 9392777 · Abstract · read 2026-10-09
Everyday exposure	5/10	Ranking 51 seafood varieties by their share of mercury in the US seafood supply, tuna (canned and fresh) accounted for 37.4% of total mercury inputs, while most of the highest-mercury fish except swordfish were minor contributors. Ranking the contributions of commercial fish and shellfish varieties to mercury exposure in the United States: implications for risk communication · Environ Res 2010 DOI 10.1016/j.envres.2009.12.006 · PMID 20116785 · Abstract · read 2026-10-09
Persistence	7/10	In 27 volunteers who ate fish at the tolerable weekly methylmercury intake for 14 weeks, blood mercury rose from 6.7 to 26.9 ng/g, and its half-life after they stopped was 94 days (57 days after subtracting background). Hair-to-blood ratio and biological half-life of mercury: experimental study of methylmercury exposure through fish consumption in humans · J Toxicol Sci 2012 DOI 10.2131/jts.37.123 · PMID 22293416 · Abstract · read 2026-10-09

Ratings are editorial. A study listed here supports the rating; it did not compute it. How the index is built

What this means for you

The persistence rating is the standout concern here — these compounds linger in the body and environment for years. Mercury bioaccumulates up the food chain, concentrating in big long-lived predators. Small oily fish give the omega-3s with far less mercury.

Evidence strength: strong

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Lower-exposure choices

Cruciferous VegetablesMinimal · Food

Filtered Black CoffeeMinimal · Food

Small Oily Fish (Sardines)Low · Food

Organic StrawberriesLow · Food

All 50 food entries, highest burden first →