Why are molluscan shellfish particularly prone to contamination?

• A. They are filter feeders that concentrate contaminants from the environment
• B. They have shells that kill pathogens
• C. They swim rapidly to polluted areas
• D. They metabolize contaminants into harmless substances

Answer: (A)

Molluscan shellfish are particularly prone to contamination because they are filter feeders. They pump large volumes of water through their feeding structures to capture microscopic food, so any contaminants in the water—bacteria, viruses, and chemical toxins—are pulled in and accumulate in their tissues faster than they can be eliminated. This bioaccumulation means that consuming them, especially raw or lightly cooked, can transmit those contaminants to people. The shells themselves don’t kill pathogens or detoxify these substances, and these organisms don’t actively move away from polluted areas; they simply filter whatever is present in their environment. This combination of feeding biology and environmental exposure is why shellfish are such a concern for contamination.