A combination of spectral and chromatographic analytical methods has been executed to monitor chemicals in the hair of Vietnamese people. Methods were developed for the determination of some chemical elements in hair by inductively coupled-plasma atomic emission spectroscopy with limits of detection reaching 1 - 100 μg·l^－1. A supercritical fluid extraction (SFE) and clean-up procedures were established for isolating organochlorine pollutants (OCPs) and organophosphorus pesticides (OPPs) from the hair of the Vietnamese test subjects. Eight OCPs and OPPs were determined by SFE with carbon dioxide only and methanol-modified carbon dioxide extraction at 350 bar and 45℃, followed by gas chromatography coupled to mass spectrometry. The results indicated that OCPs can be extracted quantitatively using CO₂ only, whereas OPPs require a modifier for extraction. The limits of detection that were found were between 0.7 to 1.3 μg·g^－1, and good linearity (r² > 0.9861) was achieved within the tested ranges. The activities of the N-acetyltransferase (NAT) and the monooxygenases cytochrome P450 (CYP 450) were determined and compared to the acetylation and oxidation phenotypes of healthy Vietnamese test subjects. The variations in the concentration of chemical elements in human hair were shown to be dependent upon the activities of the two-phase metabolic system, on the individual’s gender and the duration of residence within Russia.