Total mercury in hair samples of inhabitants of Tapajós river, Pará State, Brazil

This study evaluates human exposure to methylmercury in fishermen and their families in four villages on the Tapajos river: Rainha, Barreiras, Sao Luis do Tapajos and Parana-Mirim. Hair analyses were performed with atomic absorption spectophotometry. Total hair mercury levels varied between 2.9mg/g and 71.5mg/g. Parana-Mirim showed the lowest level. The highest level was found in Sao Luis do Tapajos and Barreiras. The hair mercury was six to seven times higher than the established safe limit of 10mg/g. No statistically significant difference was found between the mean level of total mercury taken from the inhabitants living downstream and upstream in Itaituba village (p > 0.05). These results confirm that human exposure to methylmercury is occurring on the Tapajos river and suggest that continued fish ingestion in that region is a potential risk factor for the appearance of symptoms and signs of Minamata disease. An immediate epidemiological survey program is recommended.