Total mercury and methylmercury levels in scalp hair and blood of pregnant women residents of fishing villages in the eighth region of Chile

The extent of environmental exposure to mercury through the diet (i.e., by consumption of fish and seafood), of a population group having higher than average fish and seafood consumption was assessed between 1991 and 1994 in pregnant women (PW) and nursing women (NW) residing in selected fishing villages (FVs) along the coastal zone of the Eighth Region of Chile. The control population was an equivalent group with negligible seafood consumption. The samples were scalp hair collected from the occipital region, and blood obtained by venipuncture. Total mercury (Hg-T) levels were determined by cold vapor atomic absorption spectrometry (CVAAS) in all samples, and in 20% of them by instrumental neutron activation analysis (INAA) as a reference method. Methylmercury (Me-Hg) was determined by gas chromatography with electron capture detector (GC-ECD) in hair samples of the 1994 study, after its selective isolation from human hair by volatilization in a microdiffusion cell. Significant efforts were made to validate the analytical methodology for Hg-T and Me-Hg determination in human hair, and for Hg-T determination in blood. Multiple comparison tests confirmed significant differences in Hg-T content between PW and NW in each FV and in the control group, with higher concentrations in at least five FVs which were selected for further in depth studies. A new survey was performed in the selected five FVs and in the control group in 1994, including sample collection of scalp hair (for Hg-T and Me-Hg) and blood (for Hg-T) of new PW. These results showed significantly higher mean concentrations for HgT in scalp hair (x = 2.44 +/- 1.30 mg/kg); range: 0.76 - 6.26 mg/kg; n = 40) and in blood (x = 9.04 +/- 5.05 micrograms/kg; range: 1.5 - 24.1 micrograms/kg; n = 39) with respect to the control group (scalp hair: x = 0.40 +/- 0.16 mg/kg; range: 0.20 - 0.64 mg/kg; n = 9; blood: x = 2.7 +/- 1.3 micrograms/kg; range: 0.2 - 4.8 micrograms/kg, n = 9) Also, high correlation was observed between Hg-T concentrations in scalp hair and in blood within the study group.