Total mercury content in cultured oysters from NW Mexico: health risk assessment.

The total mercury (Hg) content of the soft tissues of cultured oysters of the genus Crassostrea obtained during the dry and rainy seasons at sampling sites of NW Mexico with different degrees of urbanization, was determined by cold vapor atomic absorption spectrophotometry. Hg levels ranged from 0.05 to 0.37 µg/g (dry weight) and no significant differences (p > 0.05) related to season and sampling site were observed. The values did not exceed the limit of 1.0 µg/g (wet weight) established by Mexican legislation and by the Food and Drug Agency (FDA), and the hazard quotient was between 0.001 and 0.002. The estimated hazard quotient for MeHg ranged approximately from 0.002 to 0.01.