Swordfish is a popular fish loved for its meaty texture and savory flavor. But given its large size and high position on the food chain, many people wonder – does swordfish have high levels of mercury?
Swordfish Mercury Levels Are High
The short answer is yes, swordfish does contain relatively high mercury levels compared to many other fish.
- On average, swordfish contains 0.995 parts per million (ppm) of mercury. That’s one of the highest mercury levels among popular seafood choices.
- Some tested swordfish samples have registered mercury levels above 3 ppm, which is considered very high.
For perspective, the EPA says most fish average around 0.2 ppm of mercury. So swordfish has about 5 times more mercury than average.
How Much Mercury is Toxic?
When it comes to seafood consumption, mercury toxicity thresholds focus on the methylmercury form found in fish.
- For methylmercury exposure from fish, the EPA and WHO consider intake levels above 0.1 micrograms per kilogram of body weight per day (0.1 μg/kg-bw/day) to potentially pose health risks. This is based on effects seen in studies.
- To stay below this reference dose limit, a 140 pound person could safely consume around 2-3 servings (about 8-12 oz) per week of fish with 0.2 ppm mercury, like the FDA average. Higher mercury fish would need lower weekly limits.
- If blood mercury concentrations exceed 5 μg/L, the CDC recommends medical evaluation and exposure reduction. Levels above 15-20 μg/L are cause for concern.
- Severe toxicity symptoms may occur at blood mercury concentrations over 200 μg/L. This level would require excessive frequent consumption of high mercury fish over a long period.
- The FDA/EPA’s “do not eat” fish categories are those containing over 1 ppm mercury, since regular consumption could lead to excessive exposure.
Why Swordfish Has High Mercury
Swordfish contain elevated mercury levels because they:
- Are large predatory fish that eat smaller fish, leading to bioaccumulation of mercury up the food chain.
- Can live a long time, allowing more mercury to accumulate in tissues over time. Larger, older swordfish tend to have the highest mercury content.
- Grow to over 1,100 pounds, and larger fish tend to have higher mercury levels.
Recommendations for Swordfish Consumption
Due to the potential harm from mercury exposure, health organizations provide recommendations for limiting swordfish intake:
- Pregnant women, nursing mothers, and children should avoid swordfish entirely according to the FDA and EPA. Developing brains are especially sensitive to mercury.
- For adults, the FDA/EPA recommend limiting swordfish consumption to no more than 6 ounces (one average serving) per week. This minimizes mercury exposure while allowing adults to occasionally enjoy swordfish.
- Some organizations advise avoiding swordfish altogether just to be extra cautious about mercury exposure from seafood.
Health Risks From Mercury in Fish
The health risks posed by mercury in fish depend on:
- The amount of mercury you’re exposed to
- The frequency of consumption
- Your age and health status
For healthy adults, occasional servings of swordfish within the recommended limits are generally not a significant concern. But regular overconsumption could reach problematic exposure levels over time.
Sensitive groups like pregnant women and children should be more cautious because of developing brains’ sensitivity to mercury. Fetuses and young children are at highest risk from mercury exposure through maternal consumption.
While swordfish does have high mercury content, adults can still enjoy it in moderation along with emphasizing low mercury fish choices. Follow the expert recommendations, and swordfish can reasonably be part of a healthy seafood-rich diet for most people. But sensitive groups and especially developing children should avoid swordfish and focus on safer fish options to minimize potential mercury exposure.