Fluoride in the urine, hair, and nails of phosphate fertiliser workers.

The fluoride content in the urine, hair, and nails of 106 workers employed in a phosphate fertiliser plant was significantly raised above the control level. Positive correlations were found between the group means for concentrations of fluorides in urine and hair (r = 0.77), urine and nails (r = 0.99), and hair and nails (r = 0.70). Individual values in the whole population gave significant correlations between concentrations in urine and nails (r = 0.73). The obtained results indicate that the fluoride content in hair and nails may be used as an indicator of occupational exposure to fluorides.