Elasmobranchs are a group of fishes that include sharks, rays, and skates. They’re frequently captured as bycatch, sold for meat, and processed into products like cartilage, liver oil, and gill plates for traditional medicine and other uses. Their lack of a bony skeleton makes them easier to eat than other fishes, and the lower market value of bycatch makes them an affordable option. The consumption of sharks and rays is a common practice in many coastal areas, and has increased with the rise of global fish consumption in recent decades. As a result, the populations of a number of species, such as blue sharks and common stingrays, are at risk.

At the same time, elasmobranch meat poses serious health risks due to contamination from metals and metalloids. Pollution from agriculture, sewage, and industrial waste introduces toxic substances into aquatic ecosystems. Small fishes absorb these toxins through their skin, gills, and diet. Elasmobranchs, as mid-level and top predators, consume many smaller contaminated fishes throughout their long lifespans, leading to a buildup of toxins in their bodies. This makes their meat highly prone to contamination.

This narrative review aimed to discuss the issue of metal and metalloid contamination in elasmobranch meat and the risks it poses to human health. The authors reviewed the existing literature on toxic element levels in the meat of 10 commonly consumed shark and ray species and examined the associated health risks.

The authors first identified 20 studies published between 2005 and 2023 that measured the concentration of four major toxic elements in elasmobranch meat: arsenic, cadmium, mercury, and lead. These studies also measured selenium, an essential element known for its ability to counteract the toxic effects of mercury. The authors then compared the concentration of these elements to the allowable limits set by various regulatory agencies.

Arsenic was found to be the most prevalent of the elements in question, followed by selenium, mercury, lead, and cadmium. Cadmium concentration in elasmobranch meat nearly always exceeded allowable limits set by the strictest regulatory agencies. Mercury and lead were usually, but not always, within allowable limits. None of the examined regulatory agencies had defined safe limits for arsenic.

To assess potential health effects, the authors identified a further eight studies published between 2014 and 2024 that calculated the Hazard Quotient (HQ) of each element in elasmobranch meat. The HQ estimates the risk of adverse health effects other than cancer, with values greater than 1.0 signifying potential health risks. They also examined the Total Hazard Quotient (THQ), which sums the HQs of all contaminants in a food, and the Selenium Health Benefit Value (HBVSe), which assesses whether selenium levels are high enough to help protect against mercury toxicity.

The HQ of arsenic generally exceeded 1.0, meaning that the concentration of arsenic in elasmobranch meat is often high enough to pose health risks. Lead and selenium were the only elements with HQs consistently below 1.0. Most studies reporting THQ showed values greater than 1.0, meaning that the cumulative risk from all contaminants combined is high. While shark species had positive HBVSe values, rays often had negative HBVSe values, indicating a lack of protection from mercury toxicity.

The authors also identified several groups at elevated risk from consuming elasmobranch meat:

• Pregnant people, due to the association of mercury with adverse pregnancy outcomes;
• Infants and young children, who are at risk of neurodevelopmental disorders and other long-term health issues;
• Older individuals, who may have reduced ability to eliminate toxins; and
• People with pre-existing health conditions, who may struggle to cope with the added burdens of metal and metalloid contamination.

The analysis was limited by significant data gaps. While many studies have measured metal and metalloid levels in elasmobranch meat, far fewer have calculated the health risks these levels pose to consumers. Only three studies calculated HBVSe values, and very few assessed cancer risks. In any case, the existing evidence is a great cause for concern.

This review shows that the consumption of sharks and rays poses serious health risks due to high levels of toxins like arsenic, with some people especially vulnerable to these risks. The issue is particularly pressing in resource-poor, coastal communities, where regulatory oversight tends to be lax and consumers rely heavily on affordable protein sources. For animal advocates, the evidence presented offers another angle for arguments in favor of greater protection for threatened elasmobranch species. It also provides an opportunity to promote affordable plant-based proteins, such as beans and lentils, as a safer alternative. Ultimately, the interventions that are most effective may be the ones that consider the connection between the well-being of elasmobranchs, their aquatic environments, and the humans who rely on them both.