Effects of airborne fluorides on workers at a cryolite production plant.

Abstract

Workers in a cryolite-producing plant were the subjects of this study to identify the relationship between environmental exposure to fluoride compounds and urinary fluorine excretion. Workers were divided into three groups according to the process of cryolite production (a calcination unit and two units producing cryolite by different methods). Both the airborne fluoride concentration and the urinary fluorine concentration of workers were monitored twice a year from 1977 to 1982. Urinary fluoride levels before and after work were obtained to minimize the influence of factors other than occupational exposure which affect the body burden of fluorides. Due to improvements in the work process during the observed period, by 1982 the dust exposure level in the calcining process had been reduced to one-tenth the level in 1977. In the precalcining process, environmental hydrogen fluoride levels were closely correlated to the urinary fluoride levels of workers. Significant correlations to the urinary fluorine levels of workers in cryolite production and the recovery of fluorides were also found. As a result, urinary fluoride concentration is considered to be a good indicator for monitoring the effects of fluoride compounds on workers’ health.