Chromium status of tannery workers in relation to metabolic disorders

Chromium (Cr), being an excellent tanning agent, is widely used in the leat her industry. In the process of leather production, tannery workers are exp osed to either inorganic Cr(III) compounds or Cr bound to proteins (leather dust). The total Cr content in tannery air (1-54 mu g m(-3)) is rather hig h in comparison to ambient air (4-6 ng m(-3)) but the amount of Cr in inhal able particles (<10 mu m) is two to three orders of magnitude less (20-60 n g m(-3)). The total daily intake of Cr was estimated by the analysis of die t (24.3 +/- 4.0 mu g Cr day(-1)), drinking water (0.3 +/- 0.1 mu g Cr dm(-3 )) and ambient air. The contribution of the latter was dominant for tannery workers and almost negligible (8%) for the unexposed population. Chromium is an essential nutrient required for sugar and fat metabolism. Th e normal dietary intake of Cr for the occupationally unexposed population i s found to be suboptimal (<30 mu g Cr day(-1)) whereas tannery workers rece ive on average 150-325 mu g of supplemental Cr day(-1). Assessment of the C r status of both populations was made on the basis of the Cr contents of th eir scalp hair, pre-shift urine and thermally induced sweat. The median Cr contents in these tissues and fluids were significantly higher (P < 0.01) i n tannery workers (hair: 4 mu g Cr g(-1), urine: Cr/creatinine 1.7 mu g Cr g(-1), sweat: 25 mu g Cr dm(-3)) in comparison with the control group (hair : 0.16 mu g Cr g(-1) urine: Cr/creatinine 0.13 pg Cr g(-1), sweat; 0.7 mu g Cr dm(-3)). Tannery workers absorbed up to 13 times more Cr in comparison to controls, the amount varying considerably depending on the workplace and duration of exposure. The main route of Cr absorption appears to be throug h the gastrointestinal tract, where medium to large particles play a domina nt role. The absorption of Cr from leather dust may be more efficient in co mparison to inorganic Cr(III) compounds. Under normal circumstances sweat C r losses represent at least 20% of urinary Cr excretion. The incidence of glucose intolerance and disturbed lipid metabolism was com pared between the unexposed (control) population (n=150) and a population o f tannery workers (n=138) from the same residential area. The percentage of glucose-intolerant subjects was significantly (P<0.01) lo wer in the older subgroup (age>48 years), who were even more obese, but not in the whole tannery population in comparison to controls. In the group of subjects displaying glucose intolerance, those from the control population showed a significantly higher body mass index (BMI) of 32.3 and a consider ably larger proportion of females (86%) in comparison to subjects from the tannery population (28.2 and 60%, respectively). There was no significant d ifference in total serum cholesterol levels between the groups. Results of other lipid variables, such as high-density lipid (HDL) cholesterol, low-de nsity lipid (LDL) cholesterol and triglycerides, are controversial: namely, the HDL/LDL ratio was higher for the controls, who showed in contrast sign ificantly higher serum triglyceride levels in comparison to the older subgr oup of tannery workers. The possible effects of other parameters on serum H DL-cholesterol level are outlined but the influeuce of Cr on lipid metaboli sm in tannery workers remains unclear. Copyright (C) 1999 John Wiley & Sons , Ltd.