Changes in manganese and small cobalt blood levels of lead-exposed workers.

Blood levels of manganese and cobalt were analyzed with graphite furnace atomic absorption spectrophotometry in three groups of workers: non-exposed, middle-exposed and heavy-exposed to lead from five lead-acid battery factories located in Mexico City. Manganese levels were significantly higher in the heavy-exposed workers than in the non-exposed subjects. Cobalt in blood concentrations was found to be lowered in both middle and heavy exposed workers as compared to the control group. The significance of these findings is discussed in terms of the possible mechanisms underlying these observations.