Exposure to tremolite asbestos and respiratory health in Swedish dolomite workers.

OBJECTIVES: Deposits of carbonate rock like limestone and dolomite may contain tremolite asbestos. This study assessed the exposure to tremolite asbestos and the respiratory health of Swedish dolomite workers. METHODS: 95% of 137 eligible workers at two dolomite producing companies completed a self administered questionnaire that included questions on respiratory symptoms and were examined with spirometry as well as chest radiography. Total exposure to dust was gravimetrically measured and the tremolite asbestos content of the dust was assessed with polarisation and phase contrast microscopy. RESULTS: Dolomite dust concentrations were moderate (median 2.8 mg/m3) and tremolite asbestos concentrations were generally below the limit of detection (<0.03 fibres/ml). Somewhat higher values, around 0.1 fibres/ml, were obtained in manual stone sorting and bagging. Respiratory symptoms suggestive of chronic bronchitis were more related to smoking than to estimates of individual exposure to dust. The mean vital capacity was 0.2 l lower than expected after adjustment for sex, age, height, and smoking but the decline in lung function was not associated with current or cumulative exposure to dust in a clear cut way. Two definite cases of pleural plaques and one possible case of simple pneumoconiosis were noted, but the plaques could not be attributed exclusively to exposure to tremolite asbestos. CONCLUSIONS: Dolomite mining and milling may indeed entail low levels of exposure to tremolite asbestos, but this exposure was not a strong determinant of respiratory symptoms, lung function, or pneumoconiosis in exposed Swedish workers. This was true also for dolomite dust. The hazards of exposure to tremolite asbestos may vary across deposits, however, and additional studies at other sites of carbonate rock exploitation are warranted.

Porphyrin status in aluminum foundry workers exposed to hexachlorobenzene and octachlorostyrene.

The possible interference of hexachlorobenzene and octachlorostyrene (i.e., thermal byproducts from hexachloroethane in aluminum degassing) with porphyrin metabolism was investigated in exposed workers. Urine specimens from 9 male aluminum foundry workers (i.e., smelters) at 6 different companies and from 18 controls-matched for sex, age, residence, and socioeconomic status-were analyzed for total porphyrins and porphyrin isomers. Workers exposed to hexachlorobenzene and octachlorostyrene had a statistically significant increase in urinary total porphyrins, compared with controls (mean +/- standard deviation: 13.63 +/- 11.13 micromol/mol creatinine and 6.24 +/- 3.84 micromol/mol creatinine, respectively; p = .02). The authors attributed the results mainly to differences in excretion of coproporphyrins-notably coproporphyrin III. Erythrocyte uroporphyrinogen decarboxylase activity was similar in both groups. There was a high correlation between levels of hexachlorobenzene and octachlorostyrene, respectively, in plasma and urinary excretion of porphyrins; these findings, however, relied heavily on 1 subject for whom extreme values were obtained. The results indicated that occupational exposure to hexachlorobenzene and octachlorostyrene in aluminum degassing with hexachloroethane may affect porphyrin metabolism in a manner consistent with early secondary coproporphyrinuria-the first recognized step in the development of chronic hepatic porphyria. It was also noted that changes remained detectable some years after exposure ceased.

Hexachlorobenzene and octachlorostyrene in plasma of aluminium foundry workers using hexachloroethane for degassing.

OBJECTIVES: To study the load of selected organochlorine compounds in the blood of aluminium foundry workers who use hexachloroethane as a degassing agent for aluminium and to measure some possible effects on internal organs. METHODS: Plasma from nine male aluminium foundry workers with past experience of use of hexachloroethane and 18 controls (two controls per exposed case) matched for residence, sex, age, and socioeconomic status was analysed for hexachlorobenzene (HCB), (P-HCB), and octachlorostyrene (P-OCS) with low resolution gas chromatography-mass spectrometry. Serum samples from the same subjects were analysed for standard kidney, pancreas, and liver function variables. Analysis of variance (ANOVA) with the triplets retained, a non-parametric test, and linear regression were used for the analysis. RESULTS: A fourfold increase of mean P-HCB was found among the exposed subjects compared with the controls (313.1 v 66.9 ng/g lipid; P < 0.01; (ANOVA model)). For P-OCS this difference was even larger (54.6 v 0.7 ng/g lipid; P < 0.01). Results were still significant (P < 0.05) with non-parametric testing. Within the exposed group there was a good correlation between the ln P-HCB (r = 0.80) and ln P-OCS (r = 0.91), respectively, with the cumulative number of years of exposure to hexachloroethane. No significant difference in kidney, pancreas, or liver function was found between the two groups. CONCLUSIONS: Aluminium degassing with hexachloroethane may increase the body burden of selected organochlorine compounds as reflected by HCB and OCS measurements. With the inherent limitations of this investigation no signs of subclinical organ toxicity were found.

Exposure to cobalt chromium dust and lung disorders in dental technicians.

BACKGROUND: Dental technician's pneumoconiosis is a dust-induced fibrotic lung disease of fairly recent origin. This study was carried out to estimate its occurrence in Sweden. METHODS: Thirty seven dental technicians in central and south eastern Sweden with at least five years of exposure to dust from cobalt chromium molybdenum (CoCrMo) alloys, identified by postal survey, agreed to undergo chest radiography and assessment of lung function and exposure to inorganic dust. RESULTS: Six subjects (16%; 95% confidence interval 6% to 23%) showed radiological evidence of dental technician's pneumoconiosis. The lung function of the study group was reduced compared with historical reference material. With local exhaust ventilation dust levels were generally low, whereas in dental laboratories without such equipment high levels of dust, particularly cobalt, were found. CONCLUSIONS: Pneumoconiosis may result from exposure to inorganic dust in the manufacturing of CoCrMo-based dental constructions. It is possible to reduce this hazard substantially by local exhaust ventilation.