PANAJI
A recent study by scientists from the National Institute of Oceanography (NIO) has raised concerns over cadmium contamination in oysters along the Goa coast, warning that the regular consumption of the contaminated shellfish poses a greater public health risk.
The findings, published last month under the research paper "Distribution, Bioaccumulation and Human Health Risk of Mercury and Cadmium in Coastal Sediments and Oysters along the Goa Coast, India," show that oysters (Saccostrea cucullata) are accumulating cadmium at concentrations exceeding the permissible safety limit at most sampling sites. The researchers analysed surface sediments and oysters collected from various locations along Goa's coastline to assess the distribution of cadmium (Cd) and mercury (Hg), their ecological impacts and potential risks to consumers. “Overall, the findings suggest that cadmium represents the primary environmental and public health concern along the Goa coast, whereas mercury currently poses comparatively low ecological and human health risks,” the study concluded. The study found that average cadmium concentration in sediments was 0.16 mg/kg, well below internationally accepted sediment quality guideline thresholds. Mercury concentrations were even lower at 0.005 mg/kg, indicating minimal contamination of coastal sediments.
However, the study found a stark contrast in oysters, which exhibited a mean cadmium concentration of 3.37 mg/kg, exceeding permissible limits at most locations due to high bioaccumulation. Mercury levels in oysters averaged 0.071 mg/kg, remaining within seafood safety standards.
Using geochemical assessment tools, the researchers identified localized cadmium enrichment at Baga, while mercury contamination was found to be negligible across the coast. The health risk assessment revealed that cadmium was the dominant contributor to elevated Target Hazard Quotient (THQ) and Hazard Index (HI) values, indicating that regular consumption of contaminated oysters could pose health risks to consumers. Mercury, on the other hand, remained below thresholds associated with ecological or human health concerns.
“Consumer health risk assessment indicated that Cd was the major contributor to elevated THQ and HI values, highlighting Cd-driven consumer health concerns associated with oyster consumption,” the study noted. The researchers said the findings underscore the need for continued monitoring of heavy metals in Goa's coastal ecosystems, particularly shellfish that can accumulate contaminants over time. They noted that while the overall condition of coastal sediments remains encouraging, cadmium bioaccumulation in oysters warrants closer surveillance and management to safeguard public health and coastal food resources.
