Mercury and selenium interactions in human blood in the Wanshan mercury mining area, China

Human blood mercury (Hg), selenium (Se) and other trace element levels were investigated in the Wanshan mercury mining area. Residents living near the mine waste heaps had significantly elevated blood Hg, Se and arsenic (As) levels, which indicates the impact from Hg mining and smelting activities. Rice samples showed high Se levels, as 72.6% of total Se intake comes from rice consumption. The means of the Se:total Hg (THg) and Se:methyl Hg (MeHg) molar ratios were 60.7±27.1 and 110±53.6 respectively. Blood Se:Hg molar ratios were negatively correlated with blood Hg levels. 80.2% of the study population had blood THg levels that exceeded the 5.8μg/L regulation level set by the USEPA, which indicated the risk of Hg exposure. On the other hand, the blood Se levels were within a safe-level range, and dietary Se intake protected local residents who suffered from Hg exposure.