Do Scallops Have a Lot of Heavy Metals?

November 28, 2025 •

4 min read

According to the U.S. Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA), scallops are considered a 'good choice' with lower mercury levels. However, scallops may accumulate other heavy metals, like cadmium, and the overall risk depends on the scallop's specific habitat.

Quick Summary

Scallops can accumulate heavy metals, especially cadmium, but levels depend on location and the part of the scallop consumed. The adductor muscle typically contains far lower concentrations than the viscera, which is often removed during processing. Most health risks are associated with high-cadmium areas, while mercury levels in scallops are generally low.

Key Points

Cadmium is the primary heavy metal concern: Scallops, particularly their viscera and kidneys, can hyperaccumulate cadmium, a toxic heavy metal, depending on their habitat.
Low mercury levels: Scallops are considered a low-mercury seafood option, and are safe for consumption in that regard for most people.
Viscera is the main source of heavy metals: The highest concentration of heavy metals is found in the dark, soft digestive gland (viscera), which is removed from commercially sold adductor muscles.
Adductor muscle is safe to eat: The white adductor muscle, the part most commonly eaten, has very low heavy metal levels and is generally considered safe.
Geographic location matters: The amount of heavy metals in scallops varies significantly based on water quality and where they were harvested.
Responsible consumption mitigates risk: Purchasing processed scallops (adductor muscle only) or properly cleaning whole scallops by removing the viscera minimizes heavy metal exposure.
Health benefits often outweigh risks: For most healthy adults consuming scallops in moderation, the nutritional benefits typically outweigh the risks associated with heavy metal exposure, especially when following proper preparation.

Scallops and Heavy Metal Accumulation: A Deeper Look

How Do Scallops Accumulate Heavy Metals?

As filter-feeding bivalves, scallops draw water through their systems to extract plankton and other nutrients. Unfortunately, this process also means they filter and accumulate heavy metals present in the surrounding water and sediment. The specific levels of contamination are highly dependent on the water quality and the location where the scallops are harvested. Coastal areas with industrial runoff, ports, and mining history tend to have higher concentrations of heavy metals in their ecosystems.

The Heavy Metal Profile of Scallops

Not all heavy metals accumulate in scallops equally. Studies show a clear distinction in how different metals are absorbed and where they are stored in the scallop's body.

Cadmium (Cd): This is the most significant heavy metal concern regarding scallop consumption. The digestive gland (viscera) and kidney of scallops are known to be hyperaccumulators of cadmium. Some studies have found that cadmium levels in the whole soft tissue of scallops from certain regions exceed international safety guidelines. For example, cadmium concentrations in scallops from the Pacific Northwest and some farmed scallops in China have been found at very high levels.
Mercury (Hg): Unlike many larger predatory fish, scallops are notably low in mercury. The FDA and EPA list scallops as a "best choice" in terms of mercury content, making them a safe option for most consumers regarding this particular metal.
Arsenic (As): While some studies have found arsenic in scallops, the levels are generally not considered a significant health risk, especially since the arsenic is mostly in its less toxic organic form.
Lead (Pb): Lead concentrations are typically low, particularly in the adductor muscle, though it can be higher in other tissues.
Zinc (Zn): Zinc is an essential trace mineral, and while scallops can accumulate it, the levels are usually well within safe consumption limits.

The Importance of Removing the Viscera

One of the most critical factors determining the heavy metal risk from scallops is which part of the shellfish is consumed. The industry standard is to sell only the adductor muscle, the firm, white, cylindrical part of the scallop. This is because the adductor muscle contains significantly lower heavy metal concentrations than the rest of the body.

Conversely, the viscera (the darker, soft tissue attached to the muscle) contains the highest concentrations of heavy metals, particularly cadmium. Most commercially sold scallops have already had their viscera removed, making them a much safer choice. For those who harvest their own scallops, removing and discarding the viscera is a crucial step for reducing heavy metal exposure.

Health Risk Comparison: Scallop Adductor Muscle vs. Viscera


Feature	Scallop Adductor Muscle	Scallop Viscera (Digestive Gland)
Cadmium Levels	Very low levels; typically within international safety guidelines.	High to extremely high levels; acts as the primary storage site for cadmium.
Mercury Levels	Very low; classified as a "best choice" by regulatory bodies.	Low to moderate, but significantly higher than the muscle tissue.
Lead Levels	Low levels; generally below regulatory limits.	Higher levels; often significantly elevated compared to the muscle.
Consumption Safety	Considered safe for consumption in moderation for most people.	Not recommended for consumption due to high heavy metal bioaccumulation.
Preparation	What is typically sold and eaten. Viscera is removed.	Must be carefully removed and discarded to minimize risk.

Key Steps to Minimize Your Risk

To ensure your consumption of scallops is as safe as possible, follow these guidelines:

Buy from reputable sources: Purchase commercially prepared scallops where the viscera has already been removed.
Remove the viscera yourself: If you are harvesting or buying fresh, whole scallops, be sure to carefully remove and discard the viscera before cooking.
Choose species from cleaner waters: Some studies suggest that scallops from certain areas, like those from the Yellow Sea compared to the Bohai Sea, may have lower overall heavy metal concentrations.
Maintain a balanced diet: As with all foods, variety is key. The health benefits of moderate scallop consumption generally outweigh the risks of heavy metal exposure, especially when limiting intake to the adductor muscle.

Conclusion: Responsible Consumption is Key

While the question "Do scallops have a lot of heavy metals?" does not have a simple "yes" or "no" answer, the reality is that the potential for heavy metal accumulation, especially cadmium, is a legitimate concern for certain parts of the shellfish. The good news is that for the average consumer, this risk is minimal. By sticking to the adductor muscle, which is low in mercury and is commercially processed to remove the high-cadmium viscera, you can enjoy scallops as part of a healthy, balanced diet. For those who enjoy harvesting or preparing whole scallops, the simple act of removing the digestive gland is enough to drastically reduce the risk. Ultimately, consuming seafood responsibly and being aware of its source and preparation method is the best way to enjoy its nutritional benefits while mitigating any potential risks.

For more detailed information on seafood safety, you can refer to the FDA's Guide to Eating Fish.

Frequently Asked Questions

The viscera, or digestive gland, of a scallop contains the highest concentrations of heavy metals, especially cadmium. The adductor muscle, which is the white, firm part typically sold, has much lower levels.

Yes, commercially sold scallops are generally safe to eat. They are typically sold as just the adductor muscle, and the heavy metal-accumulating viscera has been removed.

Not necessarily. The level of heavy metal accumulation depends more on the specific water quality of the harvesting location, whether wild or farmed, rather than the distinction between wild or farmed itself.

Cadmium is the primary heavy metal of concern in scallops, particularly due to its high accumulation in the viscera.

Yes, scallops are one of the seafood options with the lowest mercury content. The FDA and EPA classify them as a 'best choice' for consumption based on their low mercury levels.

The safest way is to consume only the adductor muscle. If you are preparing whole scallops, ensure the dark, soft viscera is completely removed and discarded before cooking.

No, heavy metal levels are not uniformly high in all scallops. Concentrations vary significantly based on geographic location and the level of environmental pollution in the water they inhabit.