Swordfish (High Mercury)

A large, long-lived predatory fish high on the food chain.

35High burden · out of 100

Cleaner swapLower-mercury fish like salmon, sardines or trout

How this score is built

100Start
63.2Chemical hazard 8 × 4.6−36.8
53Everyday exposure 3 × 3.4−10.2
35Persistence 7 × 2.6−18.2, then rounded to 35
HighThe band35 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	8/10	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	3/10	In muscle from 82 Pacific swordfish, total mercury ranged from 228 to 2,090 ppb; fish over about 96 kg dressed weight are predicted to exceed the 1,000 ppb action level used in the US, Canada and Europe. Postharvest correlation between swordfish (Xiphius gladius) size and mercury concentration in edible tissues · J Food Prot 2015 DOI 10.4315/0362-028X.JFP-14-449 · PMID 25710157 · 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. Swordfish is on the FDA/EPA 'avoid' list for its high methylmercury content, which accumulates in the body. Pregnant people and young children are advised to skip it.

Evidence strength: strong

See where your whole exposure load is highest — free Exposure Score →

This entry and the whole Index, on your phone.

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 →