Relationship between external and internal parameters of exposure to manganese in workers from a manganese oxide and salt producing plant.

In a plant producing manganese (Mn) oxides and salts, 11 different workplaces were identified. The current exposure to airborne Mn (total dust, personal sampling, n = 80) varied from 0.07 to 8.61 mg/m3. The geometric mean and median values amounted approximately to 1 mg/m3 and the 95th percentile was 3.30 mg/m3. The concentration of Mn in blood (Mn-B) in a group of 141 Mn-exposed male workers ranged from 0.10-3.59 micrograms/100 ml compared to 0.04-1.31 micrograms/100 ml in a group of 104 control subjects. The ranges of the concentrations of Mn in urine (Mn-U) were 0.06-140.6 and 0.01-5.04 micrograms/g creatinine for the exposed and control groups, respectively. The average level of Mn-B in the Mn group was more than twice as high as in the control group (arithmetic mean, 1.36 vs 0.57 microgram/100 ml) and that of Mn-U was ten times higher in the Mn group (geometric mean, 1.56 vs 0.15 microgram/g creatinine). The Mn-B level did not change significantly after 8 h of Mn exposure, whereas the Mn-U level dropped rapidly when exposure ceased (half-life less than 30 h). On an individual basis, neither Mn-B nor Mn-U correlated with the current levels of Mn-air or duration of Mn exposure. There was also no relationship between Mn-B and Mn-U. On a group basis, there was no correlation between the mean Mn-B levels and the current levels of Mn-air at each workplace.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiological survey among workers exposed to manganese: effects on lung, central nervous system, and some biological indices.

A cross-sectional epidemiological study was carried out among 141 male subjects exposed to inorganic manganese (Mn) in a Mn oxide and salt producing plant (mean age 34.3 years; duration of exposure, mean 7.1 years, range 1-19 years). The results were compared with those of a matched control group of 104 subjects. The intensity of Mn exposure was moderate as reflected by the airborne Mn levels and the concentrations of Mn in blood (Mn-B) and in urine (Mn-U). A significantly higher prevalence of cough in cold season, dyspnea during exercise, and recent episodes of acute bronchitis was found in the Mn group. Lung ventilatory parameters (forced vital capacity, FVC; forced expiratory volume in one second, FEV1; peak expiratory flow rate, PEFR) were only mildly altered in the Mn group (smokers) and the intensity and the prevalence of these changes were not related to Mn-B, Mn-U, or duration of exposure. There was no synergistic effect between Mn exposure and smoking on the spirometric parameters. Except for a few nonspecific symptoms (fatigue, tinnitus, trembling of fingers, increased irritability), the prevalence of the other subjective complaints did not differ significantly between the control and Mn groups. Psychomotor tests were more sensitive than the standardized neurological examination for the early detection of adverse effects of Mn on the central nervous system (CNS). Significant alterations were found in simple reaction time (visual), audioverbal short-term memory capacity, and hand tremor (eye-hand coordination, hand steadiness). A slight increase in the number of circulating neutrophils and in the values of several serum parameters (ie, calcium, ceruloplasmin, copper, and ferritin) was also found in the Mn group. There were no clear-cut dose-response relationships between Mn-U or duration of Mn exposure and the prevalence of abnormal CNS or biological findings. The prevalences of disturbances in hand tremor and that of increased levels of serum calcium were related to Mn-B. The response to the eye-hand coordination test suggests the existence of a Mn-B threshold at about 1 microgram Mn/100 ml of whole blood. This study demonstrates that a time-weighted average exposure to airborne Mn dust (total dust) of about 1 mg/m3 for less than 20 years may present preclinical signs of intoxication.

Preclinical toxic effects of manganese in workers from a Mn salts and oxides producing plant.

The results of the present epidemiological study among 141 workers (mean age: 34 years) from a Mn salts and oxides producing plant in Belgium suggest that preclinical perturbations (lung function, CNS, biological parameters) may occur in subjects exposed to airborne Mn levels (7 years on the average) usually lower (total dust, geometric mean about 1 mg/m3, 95th percentile 3.3 mg/m3) than the levels actually (5 mg/m3) tolerated.