Alarming signs of mercury pollution in a freshwater area of Thailand [fish, Ophiocephalus striatus, aquatic birds]

Freshwater fish hold a position of prime importance in the diet of the population in Thailand. The present observations show that the baseline mercury contaminations of Thai fish are among the lowest in the world (mean 0.07 ppm, range 0.002-0.30 ppm in flesh). The amount of mercury in human hair was also rather low in unpolluted areas (mean 2.33 ppm, range 0.77-14.0 ppm). Aquatic birds had a mean mercury content in the pectoral muscle of 0.27 ppm (range 0.15-0.56 ppm). A local increase was, however, observed in the flesh of the fish Ophiocephalus striatus in the vicinity of a recently established Japanese caustic soda factory, where the observed mercury values varied from 0.32 ppm to 3.6 ppm. Signs of mercury accumulation in the tip portion of human hair were observed in males but not in females living in the polluted area.