ENDEMIC FLUOROSIS IN SAN-LUIS-POTOSI, MEXICO .2. IDENTIFICATION OF RISK-FACTORS ASSOCIATED WITH OCCUPATIONAL EXPOSURE TO FLUORIDE

The city of San Luis Potosi (SLP), Mexico, is located in an area where drinking water contains excessive quantities of natural fluoride. Als o in this city is located a small industry that produces hydrofluoric acid. in order to investigate both routes of exposure to fluoride (ind ustrial air and drinking water), we conducted a pilot study in workers of this industry. The study involved 60 male workers, divided into tw o groups according to their work area: the production and the office g roups. Although the exposure to fluoride by the water ingestion pathwa y was similar for both groups, the occupational exposure to fluoride w as 12 times higher in the production area. Workers in this area had hi gher levels of fluoride in urine than workers in the office area. This difference was observed in the preshift and the postshift samples. A multivariate regression analysis showed that the workplace explained 3 3% of the fluoride content of the urinary samples, whereas tap water i ngestion explained only 8%. The higher air fluoride levels in the prod uction area could explain the high number of workers who present a pre clinical phase of skeletal fluorosis. Although our results illustrate the exposure to fluoride of workers in the production area by two path ways, water and workplace air, it would be advisable to explore in mor e detail the participation of other pathways of exposure, like diet an d soft drinks.