Mercury and selenium in workers previously exposed to mercury vapour at a chloralkali plant

Dental health in workers previously exposed to mercury vapour at a chloralkali plant

OBJECTIVES

The dental health of 73 workers previously exposed to mercury vapour at a chloralkali plant was studied and compared with that of 51 non-exposed referents.

METHODS

A record of oral, periodontal, gingival and mucosal conditions, including teeth, restorations, prostheses, and oral hygiene, was established during a 30 min examination. The participants' periodontal conditions were assessed according to the community periodontal index of treatment needs (CPITN). The results with the CPITN index were also compared with previously published data for another similar population.

RESULTS

There was no significant difference between the exposed workers and the referents with respect to the number of remaining teeth, amount of amalgam restorations, crowns, bridges, or endodontically treated teeth. The oral hygiene among the exposed workers was significantly better than among the referents, but the periodontal health conditions did not significantly differ between the two groups, nor from those of another Norwegian population.

DISCUSSION

The present results seem to contradict previous reports claiming tooth loss as a possible result of exposure to mercury vapour.

Assessment of renal dysfunction in workers previously exposed to mercury vapour at a chloralkali plant

Urinary albumin concentration (U-alb) and N-acetyl-beta-D-glucosaminidase (U-NAG) and glomerular basement membrane antibodies (a-GBMs) in serum samples were measured in 77 chloralkali workers previously exposed to mercury (Hg) vapour and 53 age matched referents. The exposure ceased on average 12.3 (range 1-35) years before the study. The mean exposure time was 7.9 (range 1.1-36.2) years. The mean yearly urinary Hg concentration (U-Hg) was 531 nmol/l. The concentrations of the urinary isoenzymes NAG A (U-NAG A) and NAG B (U-NAG B) were determined in 30 highly exposed subjects and 30 referents. No differences in U-alb or U-NAG, U-NAG A, or U-NAG B were found between the groups. Higher concentrations of a-GBMs were found among subjects who stopped exposure a short time before the study, but there was no association between a-GBMs and U-alb. The U-NAG and U-NAG A were negatively correlated with storage time. The results may suggest that microalbuminuria and enzymuria reported in subjects with ongoing exposure to Hg vapour are reversible in most instances.

Relation between exposure related indices and neurological and neurophysiological effects in workers previously exposed to mercury vapour

A cross sectional study of aspects of their neurology was carried out on 77 chloralkali workers previously exposed to mercury (Hg) vapour and compared with 53 age matched referents. The chloralkali workers had been exposed for an average of 7.9 years at a concentration of 59 micrograms Hg/m3 in the working atmosphere. The individual mean urinary concentration of Hg for each year of exposure was 531 nmol Hg/1. On average the exposure had ceased 12.3 years before the examinations. Both the median sensory nerve conduction velocity and the amplitude of the sural nerve were associated with measures of cumulative exposure to Hg. An association was also found between years since first exposure to Hg and aspects of the visual evoked response. Previously exposed subjects with postural tremor or impaired coordination also had alterations in visual evoked response. These results may indicate an effect of previous exposure to mercury vapour on the nervous system, possibly in the visual pathway, cerebellum, and the peripheral sensory nerves.