Reactive hyperemia and baseline pulse amplitude among smelter workers exposed to fine and ultrafine particles.

OBJECTIVE: Ambient exposure to fine particles is associated with increased cardiovascular morbidity and mortality. Associations between occupational particulate matter (PM) exposure and cardiovascular disease have been studied less. The objective of this study was to examine associations between PM exposure and endothelial function among workers in Norwegian smelters. METHODS: We examined endothelial function with Endo-PAT equipment after a working day (WD) and on a day off (DO) in 59 furnace workers recruited from three metal smelters in Norway. The difference in baseline pulse amplitude (BPA) and reactive hyperemia index (RHI) between the 2 days was analysed in relation to individual exposure to PM < 250 nm (PM250) or the respirable aerosol fraction of particles, and adjusted for relevant covariates. RESULTS: The exposure to PM250 ranged from 0.004 to 5.7 mg/m3. The mean BPA was significantly higher on WD relative to DO (772 vs. 535, p = 0.001). This difference was associated with PM concentrations among participants ≥ 34 years, but not among the younger workers. Reactive hyperemia was significantly lower on workdays relative to days off (1.70 vs. 1.84, p = 0.05). This difference was observed only among participants above the age 34. No associations with PM exposure were observed. CONCLUSIONS: PM exposure was associated with higher BPA among participants older than 34 years. BPA reflects microvessel pulsatility. Our results may indicate an age-dependent cardiovascular susceptibility to PM exposure. Endothelial function measured by RHI was reduced on WD among participants 34 years and older, but we found no associations between PM exposure and RHI.

The impact of iron status and smoking on blood divalent metal concentrations in Norwegian women in the HUNT2 Study.

Low iron (Fe) stores may result in increased absorption of divalent metals, in particular cadmium (Cd). We have previously shown that in non-smoking women participating in the Norwegian HUNT2 cohort study this also included other divalent metals, e.g. manganese (Mn) and cobalt (Co). The diet is the main source of metals in non-smoking individuals, whereas in smoking individuals tobacco smoke contributes significant amounts of Cd and lead (Pb). The aim of the present study was to investigate the impact of smoking on the relationship between low iron status and divalent metals. Blood concentrations of the divalent metals Cd, Mn, Co, Pb, copper (Cu) and zinc (Zn), determined using an Element 2 sector field mass spectrometer (ICP-MS), were investigated in smoking women of fertile age (range 21-55 years) (n=267) from the HUNT2 cohort. Among these, 82 were iron-deplete (serum ferritin<12µg/L) and 28 had iron deficiency anaemia (serum ferritin<12µg/L & Hb<120g/L). 150 (56%) women smoked 10 or more cigarettes daily, 101 (38%) had smoked for more than 20 years, and 107 (40%) had smoked for 11-20 years. Results from the smoking population were compared with results from our previous study in non-smoking women (n=448) of which 132 were previous smokers, all from the same cohort. Increasing concentrations of Cd in blood were observed for previous smokers, low-to-moderate smokers and high intensity smokers in all subgroups compared to never smokers, and according to age groups, education level, BMI and serum ferritin. Smokers had higher Pb concentrations than non-smokers in all subgroups, but less pronounced than for Cd. Smoking was not associated with Mn and Co concentrations in blood. In multiple regression models, low ferritin was associated with increased blood concentrations of Cd, Pb, Mn and Co. Ferritin was strongly associated with Cd at low smoking intensity, but was not a significant factor in heavy smokers, where intensity and duration of smoking emerged as main determinants. Ferritin associations with Co and Pb varied with tertiles of blood Cd. Ferritin emerged as the main determinant of blood Co and Mn, while for blood Pb, age and smoking intensity had higher impact. Cu and Zn remained within reference values and no significant associations with ferritin were found. Strong positive associations between blood concentrations of Pb, Mn, Cd and Co were observed, also when controlled for their common association with ferritin. Apart from these associations, the models showed no significant interactions between the divalent metals studied. Mild anaemia (110

Particle size distribution of workplace aerosols in manganese alloy smelters applying a personal sampling strategy.

Air samples were collected by personal sampling with five stage Sioutas cascade impactors and respirable cyclones in parallel among tappers and crane operators in two manganese (Mn) alloy smelters in Norway to investigate PM fractions. The mass concentrations of PM collected by using the impactors and the respirable cyclones were critically evaluated by comparing the results of the parallel measurements. The geometric mean (GM) mass concentrations of the respirable fraction and the <10 µm PM fraction were 0.18 and 0.39 mg m(-3), respectively. Particle size distributions were determined using the impactor data in the range from 0 to 10 µm and by stationary measurements by using a scanning mobility particle sizer in the range from 10 to 487 nm. On average 50% of the particulate mass in the Mn alloy smelters was in the range from 2.5 to 10 µm, while the rest was distributed between the lower stages of the impactors. On average 15% of the particulate mass was found in the <0.25 µm PM fraction. The comparisons of the different PM fraction mass concentrations related to different work tasks or different workplaces, showed in many cases statistically significant differences, however, the particle size distribution of PM in the fraction <10 µm d(ae) was independent of the plant, furnace or work task.

Essential and toxic element concentrations in blood and urine and their associations with diet: results from a Norwegian population study including high-consumers of seafood and game.

The first aim of the study was to evaluate calculated dietary intake and concentrations measured in blood or urine of essential and toxic elements in relation to nutritional and toxicological reference values. The second aim was to identify patterns of the element concentrations in blood and urine and to identify possible dietary determinants of the concentrations of these elements. Adults with a known high consumption of environmental contaminants (n=111), and a random sample of controls (n=76) answered a validated food frequency questionnaire (FFQ). Complete data on biological measures were available for 179 individuals. Blood and urine samples were analyzed for selenium, iodine, arsenic, mercury, cadmium and lead. Principal component analysis was used to identify underlying patterns of correlated blood and urine concentrations. The calculated intakes of selenium, iodine, inorganic arsenic and mercury were within guideline levels. For cadmium 24% of the high consumer group and 8% of the control group had intakes above the tolerable weekly intake. Concentrations of lead in blood exceeded the bench-mark dose lower confidence limits for some participants. However, overall, the examined exposures did not give rise to nutritional or toxicological concerns. Game consumption was associated with lead in blood (B(ln) 0.021; 95%CI:0.010, 0.031) and wine consumption. Seafood consumption was associated with urinary cadmium in non-smokers (B(ln) 0.009; 95%CI:0.003, 0.015). A novel finding was a distinct pattern of positively associated biological markers, comprising iodine, selenium, arsenic and mercury (eigenvalue 3.8), reflecting seafood intake (B 0.007; 95%CI:0.004, 0.010). The study clearly demonstrates the significance of seafood as a source of both essential nutrients and toxic elements simultaneously and shows that exposure to various essential and toxic elements can be intertwined.

Physicochemical characterisation of different welding aerosols.

Physicochemical properties important in exposure characterisation of four different welding aerosols were investigated. Particle number size distributions were determined by scanning mobility particle sizer (SMPS), mass size distributions by separation and weighing the individual size fractions of an 11-stage cascade impactor. The size distribution of the primary particles of agglomerates, chemical composition and morphology of the particles were examined by TEM. There were significant differences in the particle number size distributions of the different welding aerosols according to the SMPS determinations. The particle mass size distributions determined gravimetrically were, however, not really different. The dominant range with respect to mass was between 0.1 and 1 µm, regardless of the welding technique. Most of the primary particles in all different welding aerosols had diameters between 5 and 40 nm. All types of primary particles had a tendency to form chainlike agglomerates. A clear size dependence of the particle chemical composition was encountered in the case of manual metal arc welding aerosol. Small particles with diameters below 50 nm were mostly metal oxides in contrast to larger particles which also contained more volatile elements (e.g. potassium, fluorine, sodium, sulphur).

[Evaluating biomarkers of exposure to electric welding aerosol].

Biologic monitoring data in electric welders revealed reliable correlation between manganese concentration in the whole blood and manganese concentrations in the workplace air. The chronic manganese intoxication patients showed reliable lower levels of urinary iron, cobalt and manganese vs. those values in the reference group.

Hygroscopic properties of the workroom aerosol in aluminium smelter potrooms: a case for transport of HF and SO2 into the lower airways.

The hygroscopic behaviour of individual aerosol particles from workplaces in a primary aluminium smelter was investigated by environmental scanning electron microscopy. At a high relative humidity, comparable with the human respiratory tract, most particles encountered in the Søderberg and Prebake potrooms either undergo partial deliquescence (leading to a water droplet with an insoluble core) or form thin water films at the surface. As gaseous HF and SO(2) are highly soluble in water, the aerosol particles may act as carrier for these two gases into the alveolar region of the lower respiratory tract. Based on a one-dimensional mass balance model, it is estimated that under peak exposure conditions (particle surface area concentration of 10(-4) cm(2) cm(-3)) approximately 10% of the initial gaseous HF may be transferred to the particle phase. For SO(2), this fraction is much lower (approximately 1%). These results indicate that at least HF may penetrate deeper into the lung in the presence of soluble particles or particles that form surface water films compared to HF alone.

[Peculiarities of nervous system functional state in electric welders exposed to manganese compounds].

Peculiarities of nervous system functional state in electric welders exposed to manganese compounds. To evaluate nervous system functional state in electric welders exposed to manganese compounds, the authors conducted transverse study with matched pairs. The electric welders' tests for response rate, diadochokinesis and grasping power were not reliable. No changes were found in tremor characteristics and posture steadiness. Bradykinesia appeared to prevail in welders.

Determination of airborne trialkyl and triaryl organophosphates originating from hydraulic fluids by gas chromatography-mass spectrometry. Development of methodology for combined aerosol and vapor sampling.

Methodology for personal occupational exposure assessment of airborne trialkyl and triaryl organophosphates originating from hydraulic fluids by active combined aerosol and vapor sampling at 1.5L/min is presented. Determination of the organophosphates was performed by gas chromatography-mass spectrometry. Combinations of adsorbents (Anasorb 747, Anasorb CSC, Chromosorb 106, XAD-2 and silica gel) with an upstream cassette with glass fiber or PTFE filters and different desorption/extraction solvents (CS(2), CS(2)-dimethylformamide (50:1, v/v), toluene, dichloromethane, methyl-t-butyl ether and methanol) have been evaluated for optimized combined vapor and aerosol air sampling of the organophosphates tri-isobutyl, tri-n-butyl, triphenyl, tri-o-cresyl, tri-m-cresyl and tri-p-cresyl phosphates. The combination of Chromosorb 106 and 37 mm filter cassette with glass fiber filter and dichloromethane as desorption/extraction solvent was the best combination for mixed phase air sampling of the organophosphates originating from hydraulic fluids. The triaryl phosphates were recovered solely from the filter, while the trialkyl phosphates were recovered from both the filter and the adsorbent. The total sampling efficiency on the combined sampler was in the range 92-101% for the studied organophosphates based on spiking experiments followed by pulling air through the sampler. Recoveries after 28 days storage were 98-102% and 99-101% when stored at 5 and -20 degrees C, respectively. The methodology was further evaluated in an exposure chamber with generated oil aerosol atmospheres with both synthetic and mineral base oils with added organophosphates in various concentrations, yielding total sampling efficiencies in close comparison to the spiking experiments. The applicability of the method was demonstrated by exposure measurements in a mechanical workshop where system suitability tests are performed on different aircraft components in a test bench, displaying tricresyl phosphate air concentrations of 0.024 and 0.28 mg/m(3), as well as during aircraft maintenance displaying tri-n-butyl phosphate air concentrations of 0.061 and 0.072 mg/m(3).

Cross shift changes in lung function among bar and restaurant workers before and after implementation of a smoking ban.

OBJECTIVE: To study possible cross shift effects of environmental tobacco smoke (ETS) on pulmonary function among bar and restaurant employees before and after the implementation of a smoking ban in Norway. METHODS: The study included 93 subjects employed in 13 different establishments in Oslo. They were examined at the beginning and end of a workshift both while ETS exposure was present and when smoking was banned. The mean exposure level of nicotine and total dust before the ban was 28 microg/m3 (range 3-65) and 275 microg/m3 (range 81-506), respectively. Following the smoking ban, the mean level of nicotine and total dust was 0.6 mug/m3 and 77 microg/m3, respectively. Assessment of lung function included dynamic lung volumes and flows. RESULTS: The cross shift reduction in forced vital capacity (FVC) among 69 subjects participating in both examinations changed from 81 ml (SD 136) during exposure to ETS to 52 ml (SD 156) (p = 0.24) following the smoking ban. The reduction in forced expired volume in one second (FEV1) during a workshift, was borderline significantly reduced when comparing the situation before and after the intervention, by 89 ml (SD = 132) compared to 46 ml (SD = 152) (p = 0.09), respectively. The reduction in forced mid-expiratory flow rate (FEF25-75%) changed significantly from 199 ml/s (SD = 372) to 64 ml/s (SD = 307) (p = 0.01). Among 26 non-smokers and 11 asthmatics, the reduction in FEV1 and FEF25-75% was significantly larger during ETS exposure compared to after the smoking ban. There was an association between the dust concentration and decrease in FEF25-75% before the ban among non-smokers (p = 0.048). CONCLUSIONS: This first study of cross shift changes before and after the implementation of a smoking ban in restaurants and bars shows a larger cross shift decrease in lung function before compared with after the implementation of the ban.

Neuropsychological effects of low mercury vapor exposure in chloralkali workers.

Neuropsychological effects were examined in 47 mercury vapor exposed male chloralkali workers with current low concentrations of urinary mercury (mean U-Hg 5.9 nmol/mmol creatinine (Cr)). Their average duration of exposure was 13.3 years, and the calculated mean concentration of U-Hg was 9.0 nmol Hg/mmol Cr per year (exposure intensity) during their time of exposure. They were compared with 47 age-matched male referents in a cross-sectional study. The two groups were not statistically significantly different with respect to neuropsychological test performance or number of self-reported subjective symptoms. The test results of the Static Steadiness Test, which assesses tremor, were not associated with exposure to mercury vapor. However current smokers had more hand tremor than non-smokers. Statistically significant associations were found between indices of current exposure (the concentration of inorganic mercury in whole blood) and the results of the WAIS Digit Symbol Test and the Benton Visual Retention Test (number of correct responses). This could indicate a small effect of current exposure on visuomotor/psychomotor speed and attention, and immediate visual memory. Whether the association found between the historical exposure intensity and the Digit Symbol Test results may represent long-term consequences of exposure cannot be determined in this study.

Chemical speciation and sequential extraction of Mn in workroom aerosols: analytical methodology and results from a field study in Mn alloy plants.

Workers in the Mn alloy producing industry are exposed to aerosols containing a variety of Mn compounds (MnO, MnO,, Mn2O3, Mn3O4, FeMn and SiMn). This paper reports a novel four-step chemical speciation/ fractionation procedure developed for characterisation of workroom aerosols collected in Mn alloy producing plants. The following components of the aerosol have been quantified: "water soluble" Mn dissolved in 0.01 M ammonium acetate: Mn0 and Mn2+ dissolved in 25% acetic acid; Mn3+ and Mn4+ dissolved in 0.5%) hydroxylamine hydrochloride in 25%) acetic acid; and "insoluble" Mn digested in aqua regia and hydrofluoric acid. Dissolution of pure Mn compounds with well-defined stoichiometries were essentially complete in the respective leaching steps with detectable amounts of < 1% in others. Recoveries of a mixed quality control sample were also acceptable in the range 92-97% for the different oxidation states. The levels measured in the inhalable and respirable fractions in three Mn alloy producing plants were approximately 300 and 35 microg m(-3) of total Mn, respectively. The most obvious feature of the speciation results is that none of the work areas is characterised by a single Mn contaminant. The predominant oxidation states in the inhalable aerosol fraction are Mn0 and Mn2+ independent of job functions/departments. The occurrence of insoluble Mn compounds in both the inhalable and respirable aerosol fractions is significantly higher during production of SiMn.

Prophylactic iron supplementation in pregnant women in Norway.

In the present study 67 non-anaemic women were randomly allocated to either 100 mg or 15 mg iron daily at about the 10. week of pregnancy. At about week 18, 30 and 36 of pregnancy, as well as 6 weeks after delivery, hemoglobin and the serum concentrations of ferritin, vitamin B12, folates, Zn, Cu and Se were monitored. Dietary allowances of other minerals and vitamins are also increased in pregnancy, and the 15 mg iron tablet was enriched with Zn (10 mg), Cu (2 mg), Se (50 microg), vitamin B12 (3 microg), and folate (0.1 mg). Neither ferritin, nor Cu, Zn or Se concentrations differed statistically significantly between the treatment groups during pregnancy. Ferritin and Zn appeared to decrease approximately parallel to the hemodilution, whereas Cu concentrations increased from a non-pregnant reference mean of 18 micromol Cu/L to a maximum mean of nearly 33 micromol Cu/L during pregnancy. Se decreased concomitantly to about 1.0 micromol Se/L. Serum folate (around 15 micromol/L) was essentially unaffected by pregnancy in the group given multivitamin/mineral supplementation, whereas the mean concentration fell below 10 micromol/L in the group supplemented with 100 mg iron daily. Our results indicate that supplementation of 15 mg Fe daily during pregnancy results in a small reduction of hemoglobin. It is suggested that additional supplementation with folate might be of importance to maintain the serum folate concentration during pregnancy.

Renal and immunologic markers for chloralkali workers with low exposure to mercury vapor.

OBJECTIVES: The aim of this study was to investigate renal function and immunologic markers among chloralkali workers with long-term low exposure to mercury vapor. METHODS: Forty-seven currently exposed workers were compared with reference workers matched for age in a cross-sectional design. RESULTS: The mean urinary mercury concentration was 5.9 (range 1.1-16.8) nmol/mmol creatinine (Cr) for the exposed workers and 1.3 (range 0.2-5.0) nmol/mmol Cr for the referents. The chloralkali workers had been exposed for an average of 13.3 (range 2.8-34.5) years. The activity of N-acetyl-beta-D-glucosaminidase in urine (U-NAG) was higher in the exposed workers (mean 0.18 U/mmol Cr versus 0.14 U/mmol Cr, P=0.02). Associations between current urinary mercury, cumulative urinary mercury, and cumulative urinary mercury per year (intensity) and U-NAG, autoantibodies to myeloperoxidase (anti-MPO) and proteinase 3 in serum, respectively, were observed. The activity of U-NAG and anti-MPO was increased in the workers with the highest exposure, as assessed by their mean intensity of exposure. The highest activity of U-NAG was observed in the exposed workers with the lower concentrations of selenium in whole blood. CONCLUSIONS: The study indicates an effect of exposure on the kidney proximale tubule cells, possibly modified by individual selenium status, and an effect mediated by neutrophil granulocytes.

Effects of low mercury vapour exposure on the thyroid function in chloralkali workers.

Forty-seven chloralkali workers exposed to mercury vapour for an average of 13.3 years were compared with 47 referents matched for age in a cross-sectional study of thyroid function. The mean urinary mercury concentration in the exposed workers was low compared with other studies of chloralkali workers: 5.9 nmol mmol-1 creatinine (range 1.1-16.8) vs 1.3 nmol mmol-1 creatinine (range 0.2-5.0) in the reference group. The median serum concentration of reverse triiodothyronine (rT3) was statistically significantly higher in the exposed subjects compared with the referents (268 pmol l (-1) and range 161-422 vs 240 pmol l(-1) and range 129-352; P = 0.009). The difference between the exposed subjects and the referents was most pronounced in the highest exposed sub-groups. The free thyroxine (T4)/free T3 ratio was also higher in the highest exposed subgroups compared with the referents. The median serum concentration of tumour necrosis factor alpha (TNF-alpha) was lower in the exposed subjects (7.3 pg ml(-1) and range 4.4-69.7 vs 8.0 pg ml(-1) and range 6.0-34.6; P = 0.004). Exposed subjects with the lowest urinary iodine (<67.8 nmol mmol(-1) Cr) had higher serum concentrations of reverse T 3 and a higher free T4/free T3 ratio than the other subjects, suggesting that a low concentration of iodine in urine may be a risk factor for increased serum concentrations of reverse T3 and the free T4/free T3 ratio in subjects exposed occupationally to mercury vapour. The study could indicate a slight effect of low mercury vapour exposure on the function of the enzyme type I iodothyronine deiodinase, possibly modified by comparatively low urinary iodine concentrations.

Neuropsychological effects associated with exposure to mercury vapor among former chloralkali workers.

OBJECTIVES: This investigation studied possible neuropsychological effects among former chloralkali workers with past exposure to mercury vapor. METHODS: Seventy-five formerly exposed workers who had been examined with an extensive neuropsychological test battery were compared with 52 referents frequency-matched for age. The tests measured general cognitive function, motor and psychomotor function, attention, memory, and learning. The groups were similar in educational level, age, and verbal comprehension. The mean exposure time to mercury vapor in the index group was 7.9 (range 1.1-36.2) years with an annual mean urinary mercury concentration of 539 (range 41-2921) nmol/(l x year). The mean time since the cessation of exposure was 12.7 (range 1.0-35.0) years. RESULTS: Performance on the grooved pegboard (dominant hand 75.8 versus 70.9 seconds, P<0.05; nondominant hand 82.2 versus 76.3 seconds, P=0.02) and the Benton visual retention test (mean number of correct reproductions 6.9 versus 7.5, P<0.05) was poorer among the formerly exposed workers when compared with the referents. In addition the subjects who had experienced the highest intensity of exposure [cumulative urinary mercury index > or =550 nmol/(l x year)] had a poorer performance on the trailmaking test, part A and B, on the digit symbol test, and on the word pairs test (retention errors). CONCLUSIONS: The presented results suggest a slight persistent effect of mercury vapor exposure on the central nervous system, mainly involving motor functions and attention, but also possibly related to the visual system. Previous exposure does not seem to have affected the workers' general intellectual level or their ability to reason logically.

Cadmium and selenium in blood and urine related to smoking habits and previous exposure to mercury vapour.

The object of this work was to investigate possible interactions of mercury, cadmium and selenium in humans. Selenium and cadmium in blood and urine were determined in this cross-sectional study of 130 males, of whom 77 had been previously exposed to mercury vapour at a chloralkali plant. Of the participants, 61.5% were smokers and 16.2% were never-smokers. The concentration of selenium in blood (B-Se) was significantly lower in subjects currently smoking more than 50 g of tobacco per week compared to never-smokers, whereas the concentration of cadmium in blood (B-Cd) was significantly higher in all categories of current smokers. In the multiple linear regression analysis, B-Se as a dependent variable was negatively associated with B-Cd, whereas current smoking habits were not included in the model as a predictor variable. In contrast, B-Cd as a dependent variable was positively associated with current as well as previous smoking habits, and negatively with both B-Se and the 'cumulative dose' of previous mercury vapour exposure. The concentration of selenium in blood was also negatively associated with B-Cd in the group of never-smokers (Spearman's r = -0.80; P < 0.001). In conclusion, these results suggest a depressive effect of cadmium on the concentration of selenium in blood, while smoking alone did not operate as a true predictor for this effect. Furthermore, previous exposure to mercury apparently modifies the concentration of cadmium in blood.

Urinary selenium excretion in workers with low exposure to mercury vapour.

Urinary selenium excretion was studied in 21 mercury vapour (Hgo)-exposed workers involved in the demolition of a chloralkali plant. The subjects had no known previous occupational exposure to mercury. Their mean pre-exposure urinary mercury concentration, determined on average 1.2 days prior to the exposure, was 0.8 nmol mmol-1 creatinine (range 0.3-1.9). Their last mean urinary mercury concentration, determined on average after 51.4 days (range 19-103) of exposure, was 4.8 nmol mmol-1 creatinine (range 1.2-10.0). The exposure ceased on average 4.1 days after the last determined urinary mercury concentration. The corresponding concentrations of urinary selenium decreased from an average of 39.1 nmol mmol-1 creatinine (range 13.9-89.5) to 29.0 nmol mmol-1 creatinine (range 10.1-52.9) (P = 0.002). This finding may indicate that even a low to moderate work-related exposure to Hgo may reduce the urinary selenium concentration in humans in a manner that is not yet fully known.

Production and surveillance of mercury exposure over 40 years at a chloralkali plant.

Mercury vapour exposure was studied for 40 years in 419 chloralkali workers. The concentration of mercury was measured in the work room (stationary) from 1953 and in urine from 1948. There were major differences in the mean urinary concentrations between different types of job. The mean urinary mercury concentration, uncorrected for urinary dilution, for all subjects varied between 30 and 250 micrograms 1.(-1) during the study period. For workers in the cell-room the correlation (r) between urinary mercury and mercury in the work room was r = 0.74 (P < 0.001), and for repair men/mechanics it was r = 0.70 (P < 0.001). The introduction of new cells and stabilizing the volume of production may have been important for reducing air-Hg and U-Hg, whereas other changes in the production process, or actions to reduce the release of mercury to the work environment, had no detectable effect. The urinary mercury concentration among all workers was related to the relative energy consumption (r = 0.83, P < 0.001).

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.