Pulmonary function in relation to total dust exposure at a bauxite refinery and alumina-based chemical products plant.

A cross-sectional study of 1,142 male employees at the Arkansas Operations of a large aluminum production company examined the effect on pulmonary function of chronic exposure to total dust produced in the mining and refining of bauxite and the production of alumina chemicals. Never smokers, ex-smokers, and current smokers were analyzed separately. Among never smokers, a pattern of decreasing FEV1 was observed in relation to increasing duration and cumulative total dust exposure. Among never smokers with cumulative total dust exposures of greater than or equal to 100 mg/m3 yr and greater than or equal to 20 yr of exposure, there was a mean reduction from the predicted FEV1 of 0.29 to 0.39 L, in addition to a 3- to 4-fold excess of observed/expected numbers of subjects with FEV1 less than 80% of predicted. These results were observed relative to an external and an internal comparison group. Among current smokers, the deviations from predicted and the excess numbers of subjects with FEV1 less than 80% of predicted were larger in all exposure groups than for the never smokers. However, the quality of the smoking data was inadequate to allow separation of the effects of smoking and dust exposure.

Prevention of bony fluorosis in aluminum smelter workers. Excretion of fluorides during a seven-day workweek -- Pt. 2.

1. The excretion of fluoride is examined among aluminum smelter workers over the course of a seven-day workweek. The data for the first three days of work is best described by the first cycle of a parabolic curve. Each curve is characteristic of the level of exposure associated with specific jobs and individual smelter hygienic conditions. 2. The variability associated with the post-shift values after apparent equilibrium is attained is extreme. Such variability is probably due in large part to differences in exposure occurring during the last few hours of that work-day. This is further augmented as essentially all the absorbed fluoride is excreted as the near-equilibrium state is attained. 3. Because of this variability, the use of the post-shift urinary fluoride concentration as an indicator of exposure conditions should be limited to groups of workers, rather than individuals, at possible risk. 4. It appears that a urinary fluoride sample taken any day after the third day of the shift is an adequate post-shift fluoride exposure indicator among these groups of workers.

Prevention of bony fluorosis in aluminum smelter workers. A five-year study of fluoride absorption and excretion -- Pt. 3.

1. A study of over 52,000 urinary fluoride determinations collected over a 5-year period among aluminum smelter workers is described. The pre-shift urinary fluoride concentration (representative of bony burden) appears to increase less rapidly than the post-shift concentration. This slow rate of bony buildup of pre-shift urinary fluoride concentrations reflects the relatively slow uptake of fluoride by osseous tissues at these levels of exposure. 2. The utility of post-shift urinary fluoride analysis is reflected by its close correlation with improvement or deterioration in work practices which determines the degree of potential fluoride exposure. 3. Over 16,000 urinary tests for protein were performed in aluminum smelter workers. The absence of correlation between urinary fluoride concentrations and the presence of albuminuria indicates the absence of renal alteration among these workers.

Prevention of bony fluorosis in aluminum smelter workers. A 15-year retrospective study of fluoride excretion and bony radiopacity among aluminum smelter workers -- Pt. 4.

1. Fifty six aluminum smelter workers with 10 to 43 years' occupational exposure, and who had been previously studied medically, were re-x-rayed. Average urinary fluoride concentrations since 1960 were estimated to range from 2.78 mg/liter preshift and 7.71 mg/liter postshift. 2. Roentgenographic studies in 1960-66 and 1974 failed to reveal any evidence of fluoride associated bony change. 3. Although these workers represent a self-selected group, their magnitude and duration of exposure far outweighs any other group working at present or in the past at this plant. The implication that they have uniformly self-selected as fluoride resistant individuals is improbable. 4. These data indicate that group post-shift ur a long period is not associated with enhanced risk of bony fluorosis. If preshift urinary fluoride concentrations are less than 4 mg/l, the same results appears to apply.

Prevention of bony fluorosis in aluminum smelter workers. Absorption and excretion of fluoride immediately after exposure -- Pt. 1.

1. A program for the prevention of excessive fluoride absorption among aluminum smelter workers is described. This surveillance is based upon knowledge of the portals of entry, distribution, bone deposition and excretory patterns of this element. 2. The control program is based on the thesis that the concentration of fluoride in the urine two to three days after cessation of work-related exposure reflects the bony burden of this element among this occupational group. Further, this program assumes that the concentration of urinary fluoride after three to five days of shift work reflects the extent of work exposure, adequacy of hygienic and engineering controls and work practices. The limitations of such program as it applies to individual samplings of workers is emphasized. 3. A balance between inhaled fluoride and urinary excretion over a 24-hour period (beginning with work exposure) is attempted. An approximate model for aluminum smelter workers in a near equilibrium F balance is constructed. The role of particle size distribution as a determinant of body loading is emphasized. Because of considerable variation in uptake possible with differing particle size distributions, the actual body F loading potential is inadequately determined on the basis of F concentrations in air. These data also suggest that gaseous fluoride is probably adsorbed upon particulates and absorbed at the alveolar level in the same fashion as respirable particulate fluoride. 4. The regression of ambient fluoride on urinary excretion suggests that the present threshold limit value for fluoride might be more appropriately set at 2 mg/M33 for an eight-hour day.