Hair samples from three groups of occupationally exposed subjects were analyzed for their lead (Pb), manganese (Mn) and mercury (Hg) contents. For lead (number of subjects, n = 209), the hair Pb ranged from 0.93 to 3527 micrograms/g (geometric mean, GM = 641) and blood Pb from 33.3 to 774 micrograms/l (GM = 341); for manganese (n = 38), the hair Mn ranged from 0.20 to 52.97 micrograms/g (GM = 2.66) and urine Mn ranged from 1.70 to 17.9 micrograms/l (GM = 5.56); and for mercury (n = 85), the hair Hg from 1.79 to 12.8 micrograms/g (GM = 5.09) and the blood Hg from 0.63 to 57.3 micrograms/l (GM = 10.9). The hair Pb was significantly (P < 0.0001) correlated to blood Pb (r = 0.85); the hair Mn to urinary Mn (r = 0.45); and the hair Hg to blood Hg (r = 0.53). The average metal content at the distal end was not significantly (P > 0.05) different from that of proximal end. The GM levels for the distal end were 223 micrograms/g (95% CI 152-347) and 2.26 (95% CI 0.97-5.29); and those for the proximal end were 186 (95% CI 97-261) and 1.18 (95% CI 0.54-2.58) for Pb and Mn respectively.(ABSTRACT TRUNCATED AT 250 WORDS)