30% of Swordfish Exceeds Mercury Safety Limits

30% of swordfish samples tested over a decade exceeded European mercury safety limits. And after years of declining, the levels are creeping back up.

10 Years of Mercury Data

Researchers analyzed 799 fish samples from Spain's food safety monitoring program between 2011 and 2021, looking at both total mercury and methylmercury levels across species, according to a 2026 study in Environ Res.

Swordfish was the worst: median mercury concentration of 0.76 mg/kg, with 30% of samples over the European legal limit. Fresh tuna came next at 0.46 mg/kg, followed by canned tuna at 0.22 mg/kg.

The Decline Reversed

Mercury in swordfish dropped by about 0.5 mg/kg from 2011 to 2016. Good news, right? Then it started climbing again, nearly back to where it started. Fresh and canned tuna also showed declines in the first half, but data got scarce after 2016.

This matters because methylmercury is a potent neurotoxin. It builds up in your body with every serving.

What You Can Do

Limit swordfish and fresh tuna, especially for pregnant women and kids. Choose lower-mercury fish like salmon, sardines, and anchovies. And pair smarter seafood choices with non-toxic kitchen alternatives.

Also see glass food containers for safer alternatives.

Source: Blanco-Calvo C, Riutort-Mayol G, Marín S, et al. (2026). Environ Res.