The present levels of heavy metals in some molluscs of the upper gulf of Thailand

This investigation was carried out as part of Thailand's participation in the global ‘Mussel Watch’ program. The levels of Cd, Cr, Cu, Pb, and Zn in the green mussel, Perna viridis, oyster, Crassostrea commercialis, and the cockle, Anadara granosa, were studied from July 1982 to November 1982. Comparison was made with the previous study in August 1981 which also included the short necked clam, Paphia undulata and moon scallop, Amusium pleuronectes. It was found that the metal levels were sufficiently low that the molluscs could be consumed without any danger to health. The salinity of the water appeared to influence the uptake as higher levels of metals were found during the flood season when salinity was lower.