Occupational exposure to airborne perfluorinated compounds during professional ski waxing

The concentration levels of 11 perfluorinated carboxylic (PFCA) and eight sulfonic (PFSA) acids were determined in the serum of 13 professional ski waxers. The same components were also determined in workroom aerosols and in fluoro containing solid ski waxes and ski wax powders. The highest median concentration (50 ng/mL) was detected for perfluorooctanoic acid (PFOA), which is around 25 times higher than the background level. For the first time perfluorotetradecanoic acid (PFTeDA) has been found in human serum. Positive statistically significant associations between years exposed as ski waxer and seven different PFCAs were observed. The serum concentrations of the PFCAs with carbon chain lengths from C(8) to C(11) were reduced by around five to 20% on average during the eight month exposure free interval, whereas the reduction was substantially larger when the carbon chain lengths were smaller than C(8) or larger than C(11). This study links for the first time PFCAs in the ski waxers serum to exposure from the work room aerosols. Not only professional ski waxers but also the significant larger group of amateur skiers and waxers are potentially exposed to these compounds.

Low iron stores are related to higher blood concentrations of manganese, cobalt and cadmium in non-smoking, Norwegian women in the HUNT 2 study

Low iron (Fe) stores may influence absorption or transport of divalent metals in blood. To obtain more knowledge about such associations, the divalent metal ions cadmium (Cd), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn) and lead (Pb) and parameters of Fe metabolism (serum ferritin, haemoglobin (Hb) and transferrin) were investigated in 448 healthy, menstruating non-smoking women, age 20-55 years (mean 38 years), participating in the Norwegian HUNT 2 study. The study population was stratified for serum ferritin: 257 were iron-depleted (serum ferritin < 12 microg/L) and 84 had iron deficiency anaemia (serum ferritin < 12 microg/L and Hb < 120 g/L). The low ferritin group had increased blood concentrations of Mn, Co and Cd but normal concentrations of Cu, Zn and Pb. In multiple regression models, ferritin emerged as the main determinant of Mn, Co and Cd (p < 0.001), while no significant associations with Cu, Zn and Pb were found. Adjusted r(2) for the models were 0.28, 0.48 and 0.34, respectively. Strong positive associations between blood concentrations of Mn, Co and Cd were observed, also when controlled for their common association with ferritin. Apart from these associations, the models showed no significant interactions between the six divalent metals studied. Very mild anaemia (110 < or = Hb < 120 g/L) did not seem to have any effect independent of low ferritin. Approximately 26% of the women with iron deficiency anaemia had high concentrations of all of Mn, Co and Cd as opposed to 2.3% of iron-replete subjects. The results confirm that low serum ferritin may have an impact on body kinetics of certain divalent metal ions, but not all. Only a fraction of women with low iron status exhibited an increased blood concentration of divalent metals, providing indication of complexities in the body's handling of these metals.

[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.

The time-trend and the relation between smoking and circulating selenium concentrations in Norway

OBJECTIVES

The objectives of this study were to investigate biomarkers of selenium status in relation to smoking habits and to analyze the time-trend of selenium in serum (S-Se) in Norway during the time period 1995-2006.

METHODS

The impact of smoking habits was investigated in a population recruited to a cross-sectional study of blue-collar workers in the southern part of the country (n=98). The time-trend was studied in all subjects who delivered blood samples for the determination of S-Se to a large commercial clinical chemistry laboratory in Norway.

RESULTS

Smokers had 0.14 and 0.20 micromol/L lower concentrations of selenium in whole blood (B-Se) and serum, respectively, than non-smokers. The amount of smoking, as assessed by the serum cotinine concentration, was negatively associated with the B-Se concentration (Pearson's r=-0.43). The 1/3 of the blue-collar workers with the lowest concentrations of B-Se or S-Se had lower activity of glutathione peroxidase in serum (S-GSHpx) than the remaining subjects. Snuff users had about the same levels of B-Se and S-Se as the non-smokers, although they had about the same amount of nicotine metabolites in urine and serum as the smokers. A decreasing trend of S-Se was observed during the observation period from 1995 to 2006. The mean concentration was 1.26 micromol/L in 1995, while the lowest mean concentration was measured in 2003 (1.01 micromol/L).

CONCLUSION

Smoking, but not snuffing, is associated with lower concentrations of B-Se and S-Se. The reduction of B-Se is negatively associated with the nicotine biomarker cotinine in serum. A substantial proportion of blue-collar workers had not maximized the activity of S-GSHpx. Selenium status may have become poorer since 1995.

[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.

A study of the bio-accessibility of welding fumes

The respiratory bio-accessibility of a substance is the fraction that is soluble in the respiratory environment and is available for absorption. In the case of respiratory exposure the amount of absorbed substance plays a main role in the biological effects. Extensive bio-accessibility studies have always been an essential requirement for a better understanding of the biological effects of different workplace aerosols, such as welding fumes. Fumes generated using three different welding techniques, manual metal arc (MMA) welding, metal inert gas (MIG) welding, and tungsten inert gas (TIG) welding were investigated in the present study. Each technique was used for stainless steel welding. Welding fumes were collected on PVC membrane filters in batches of 114 using a multiport air sampler. Three different fluids were applied for the solubility study: deionised water and two kinds of lung fluid simulants: lung epithelial lining fluid simulant (Gamble's solution) and artificial lung lining fluid simulant (Hatch's solution). In order to obtain sufficient data to study the tendencies in solubility change with time, seven different leaching periods were used (0.5, 1, 2, 4, 8, 16, 24 h), each of them with three replicates. The effect of dissolution temperature was also studied. The total amounts of selected metals in the three different welding fumes were determined after microwave-assisted digestion with the mixture of aqua regia and hydrofluoric acid. The most obvious observation yielded by the results is that the solubility of individual metals varies greatly depending on the welding technique, the composition of the leaching fluid and leaching time. This study shows that the most reasonable choice as a media for the bio-assessment of solubility might be Hatch's solution by a dissolution time of 24 h.

An epidemiological study of reproductive function biomarkers in male welders

In a cross-sectional study, the serum concentrations of inhibin B and prolactin of 96 male current welders were compared with the concentrations measured in 96 age-matched referents. Also, 23 patients who were all former welders diagnosed as having welding-related manganism were studied. The current welders' geometric mean (GM) airborne exposure to manganese (Mn) was 121 microg m(-3) (range 7-2320). The serum concentrations of prolactin adjusted for age and smoking habits (GM 193 mIU l(-1) vs. 166 mIU l(-1); p=0.047) and inhibin B adjusted for alcohol consumption (arithmetic mean (AM) 151 ng l(-1) vs. 123 ng l(-1); p=0.001) were higher in the welders compared with the referents. The whole blood Mn concentration was associated with the serum prolactin concentrations. Tobacco smoking resulted in lower serum prolactin concentrations. The GM serum prolactin concentrations of the patients did not significantly differ from that of the referents, but their AM serum inhibin B concentration was statistically significantly lower. The results may suggest an effect of Mn on the pituitary that is reversible upon cessation of exposure. Lower inhibin B concentrations in the patients could point to a functional impairment of the testicular Sertoli cells, that may be caused by a welding fume component or other factors in their work environment.

Determination of airborne trialkyl and triaryl organophosphates originating from hydraulic fluids by gas chromatography–mass spectrometry

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).

Air exposure assessment and biological monitoring of manganese and other major welding fume components in welders

In a cross-sectional study, 96 welders were compared with 96 control subjects. Also 27 former welders, all diagnosed as having manganism, were examined. Exposure to welding fumes was determined in the 96 welders, while the concentration of elements in whole blood and urine was determined in all subjects. The geometric mean (GM) concentrations of manganese (Mn) and iron in the workroom air were 97 microg m(-3) (range 3-4620 microg m(-3); n=188) and 894 microg m(-3) (range 106-20 300 microg m(-3); n=188), respectively. Thus the Mn concentration in the workroom air was on average 10.6% (GM) of that of the Fe concentration. No substantial difference was observed in the air Mn concentrations when welding mild steel as compared to welding stainless steel. The arithmetic mean (AM) concentration of Mn in whole blood (B-Mn) was about 25% higher in the welders compared to the controls (8.6 vs. 6.9 microg l(-1); p < 0.001), while the difference in the urinary Mn concentrations did not attain statistical significance. A Pearson's correlation coefficient of 0.31 (p < 0.01) was calculated between B-Mn and Mn in the workroom air that was collected the day before blood sampling. Although the exposure to welding fumes in the patients had ceased on average 5.8 years prior to the study (range 4 years-7 years), their AM B-Mn concentration was still higher than in referents of similar age (8.7 microg l(-1) vs. 7.0 microg l(-1)). However, their urinary concentrations of cobolt, iron and Mn were all statistically significantly lower.

Determination of the dialdehyde glyoxal in workroom air—development of personal sampling methodology

The dialdehyde glyoxal (ethanedial) is an increasingly used industrial chemical with potential occupational health risks. This study describes the development of a personal sampling methodology for the determination of glyoxal in workroom air. Among the compounds evaluated as derivatizing agents; N-methyl-4-hydrazino-7-nitrobenzofurazan (MNBDH), 1,2-phenylenediamine (OPDA), 1-dimethylaminonaphthalene-5-sulfonylhydrazine (dansylhydrazine, DNSH) and 2,4-dinitrophenylhydrazine (DNPH), DNPH was the only reagent that was suitable. Several different samplers were evaluated for sampling efficiency of glyoxal in workroom air using DNPH as derivatizing agent; in-house DNPH coated silica particles packed in two different types of glass tubes, impingers containing acidified DNPH solution, filter cassettes containing glass fibre filters coated with DNPH, a commercially available solid phase cartridge sampler originally developed for formaldehyde sampling (Waters Sep-Pak DNPH-silica cartridge), and the commercially available SKC UMEx 100 passive sampler originally developed for formaldehyde sampling. Aldehyde atmospheres for sampler evaluation were generated with an in-house made vapour atmosphere generator coupled to a sampling unit, with the possibility of parallel sampling. The resulting glyoxal-DNPH derivative was determined using both LC-UV and LC-APCI-MS with negative ionization. By far, the highest recovery of glyoxal was obtained employing one of the in-house DNPH coated silica samplers (93%, RSD = 3.6%, n = 12).

Renal function of chloralkali workers after the cessation of exposure to mercury vapor

OBJECTIVES

The aims of the study were to assess renal function in chloralkali workers previously exposed to mercury vapor and to assess the impact of selenium status on the biomarkers of kidney function.

METHODS

Forty-nine chloralkali workers previously exposed to mercury vapor were compared with 49 age-matched referents in a cross-sectional study. Selected biomarkers of kidney function and biomarkers of selenium status were measured. The index group had been exposed for 13.1 (range 2.8-34.5) years on the average at a mean urinary mercury excretion of 9.3 (range 4.0-25.4) nmol/mmol creatinine a year. The exposure had ceased on an average of 4.8 (range 4.2-10.0) years prior to the examinations.

RESULTS

No statistically significant differences were found between the groups for the measured biomarkers of kidney function. The serum selenium concentration and serum glutathione peroxidase activity were associated with the activity of N-acetyl-beta-D-glucosaminidase in urine (U-NAG). The results indicate that having higher glutathione peroxidase activity or a higher serum selenium concentration results in a lower excretion of U-NAG. This effect was the most pronounced in the oldest third of the participants. Apparently the well-known association between U-NAG and age could only be found for the participants with a lower selenium status.

CONCLUSIONS

Increased activities of U-NAG during ongoing exposure to mercury vapor appear to be reversible upon cessation of exposure. Selenium status has a substantial impact on U-NAG activity and should be considered in studies of U-NAG excretion.

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.

Hand tremor related to smoking habits and the consumption of caffeine in male industrial workers

Tremor was measured in 49 smokers/snuffers and in 49 non-smokers/non-snuffers in a cross-sectional study. The Kløve-Matthews static steadiness test and TREMOR 7.0 from the CATSYS test system were used to assess the hand tremor. The creatinine (cr) corrected arithmetic mean concentrations of cotinine in urine were 11 microg/g cr (range 0.1-430) in the non-smokers/non-snuffers compared to 1,417 microg/g cr (range 45-3,780) in the smokers/snuffers. The geometric mean urinary caffeine concentrations were 797 microg/g cr (range 0.5-13,330) in the non-smokers/non-snuffers versus 654 microg/g cr (range 0.9-7,470) in the smokers/snuffers. Increased tremor was found in the group of smokers/snuffers compared to the non-smokers/non-snuffers for several parameters on the tremor measurements, e.g. geometric mean tremor intensity of 0.14 m/s(2) (range 0.09-0.40) in the smokers/snuffers versus 0.11 m/s(2) (range 0.07-0.22) in the non-smokers/non-snuffers for the dominant hand were quantified. Also the mean scores on the static steadiness test were inferior in the smokers/snuffers, in particular for the number of touches. The results further indicate that the frequency dispersion is smaller in the smokers/snuffers compared to the non-smokers/non-snuffers. No systematic association was observed between the biomarkers of nicotine and caffeine exposure and the tremor measurements. However, older age appeared to be an important predictor for the magnitude of tremor in the smokers/snuffers, but not in the non-smokers/non-snuffers.

Airborne exposure and biological monitoring of bar and restaurant workers before and after the introduction of a smoking ban

The aims were to assess the impact of a total smoking ban on the level of airborne contaminants and the urinary cotinine levels in the employees in bars and restaurants. In a follow up design, 13 bars and restaurants were visited before and after the implementation of a smoking ban. Ninety-three employees in the establishments were initially included into the study. The arithmetic mean concentration of nicotine and total dust declined from 28.3 microg m(-3) (range, 0.4-88.0) and 262 microg m(-3) (range, 52-662), respectively, to 0.6 microg m(-3) (range, not detected-3.7) and 77 microg m(-3) (range, not detected-261) after the smoking ban. The Pearson correlation coefficient between airborne nicotine and total dust was 0.86 (p < 0.001; n = 48). The post-shift geometric mean urinary cotinine concentration declined from 9.5 microg g(-1) creatinine (cr) (95% CI 6.5-13.7) to 1.4 microg g(-1) cr (95% CI 0.8-2.5) after the ban (p < 0.001) in 25 non-snuffing non-smokers. A reduction from 1444 microg g(-1) cr (95% CI 957-2180) to 688 microg g(-1) cr (95% CI 324-1458) was found (p < 0.05) in 29 non-snuffing smokers. The urinary cotinine levels increased from 11.7 microg g(-1) cr (95% CI 7.0-19.6) post-shift to 21.9 microg g(-1) cr (95% CI 13.3-36.3) (p < 0.01) in the next morning in 24 non-snuffing non-smokers before the smoking ban. A substantial reduction of airborne nicotine and total dust was observed after the introduction of a smoking ban in bars and restaurants. The urinary cotinine levels were reduced in non-smokers. The decline found in smokers may suggest a reduction in the amount of smoking after intervention. In non-smokers cotinine concentrations were higher based on urine sampled the morning after a shift than based on urine sampled immediately post-shift.

Ultrafine particles at workplaces of a primary aluminium smelter

The number concentration and size distribution of ultrafine particles in a Søderberg and a prebake potroom of an aluminium primary smelter have been measured using a scanning mobility particle spectrometer. The particle morphology was studied by transmission electron microscopy (TEM). The study shows the existence of elevated number concentrations of ultrafine particles in both potrooms. The main source of these particles is likely to be the process of anode changing. The ultrafine particles were measured directly at the source but could also be identified as episodes of high number concentrations in the general background air. Unlike the larger particles belonging to the 50-100 nm mode, the nanoparticle mode could not be detected in the TEM indicating that they may not be stable under the applied sampling conditions and/or the high vacuum in the instrument.

The Kløve–Matthews Static Steadiness Test Compared with the DPD TREMORComparison of a Fine Motor Control Task with Measures of Tremor in Smokers and Manganese-Exposed Workers

The aim of this study was to compare two tests for tremor/fine motor control as regards their sensitivity in relation to effects on tremor of exposure to manganese and cigarette smoke. One hundred manganese-exposed workers were compared with 100 age-matched referents. The subjects were tested with the Kløve-Matthews static steadiness test (hole tremormeter) and the DPD TREMOR (accelerometer). The manganese-exposed subjects showed increased postural tremor compared to the referents. The tremor had a larger frequency dispersion among the exposed subjects than among the referents as assessed by the TREMOR 7.0 test system, indicating that the tremor had a pattern where the power was burned at a wider spectre of frequencies among the exposed subjects than among the referents. The two tests differed in their ability to demonstrate tremor, depending of the type of exposure (manganese or cigarette smoke). The static steadiness test was better than the TREMOR at discriminating between manganese-exposed subjects and referents while the TREMOR was better at discriminating between smokers and non-smokers than the static steadiness test. The tests also differed in their ability to demonstrate tremor depending on the frequency of tremor. The Tremor Intensity I was higher for subjects with higher tremor frequency, while no such effect was found for the static steadiness test parameters. When studying the effects of exposures where the quality of the tremor is unknown, it is suggested to include at least two tremor tests, one based on acceleration and the other on displacement.

A neurobehavioral study of chloralkali workers after the cessation of exposure to mercury vapor

Neurobehavioral functions were examined in 49 male workers who had been previously exposed to mercury vapor. They were compared with 49 age-matched male referents in a cross-sectional study. The average duration of exposure in the index group was 13.1 years at a calculated mean urinary mercury (U-Hg) concentration of 9.3 nmol Hg/mmol creatinine (Cr.)/year. The exposure had ceased on average 4.8 (range 4.2-10.0) years prior to the examinations. Forty-one exposed participants and 40 referents had also been examined approximately 5 years previously, while they were still under ongoing exposure. The neurobehavioral test scores and the number of subjective symptoms were similar in the previously exposed subjects and the referents. No significant differences in the development of the neurobehavioral test scores were observed between those 41 previously exposed subjects who had also been examined while they were still being exposed when compared to the 40 referents. However, the difference in the Digit Symbol Test scores between the two occasions was associated with the concentration of inorganic mercury in whole blood while they were still under exposure. The results suggest that no long-term effects of mercury vapor exposure are found at the exposure level experienced by these workers. The study may indicate that the test performance on the Digit Symbol Test improves after exposure cessation in the subjects with the highest B-Hg concentrations, and that this test may be quite sensitive to the effects of mercury vapor exposure.

Reaction of Glyoxal with 2‘-Deoxyguanosine, 2‘-Deoxyadenosine, 2‘-Deoxycytidine, Cytidine, Thymidine, and Calf Thymus DNA: Identification of DNA Adducts

Glyoxal (ethanedial) is an increasingly used industrial chemical that has been found to be mutagenic in bacteria and mammalian cells. In this study, the reactions of glyoxal with 2'-deoxyguanosine, 2'-deoxyadenosine, 2'-deoxycytidine, cytidine, thymidine, and calf thymus DNA have been studied in aqueous buffered solutions. The nucleoside adducts were isolated by reversed-phase liquid chromatography and characterized by their UV absorbance and 1H and 13C NMR spectroscopic and mass spectrometric features. The reaction with 2'-deoxyguanosine gave one adduct, the previously known 3-(2'-deoxy-beta-D-erythro-pentofuranosyl)-5,6,7-trihydro-6,7-dihydroxyimidazo[1,2-a]purine-9-one adduct. The reaction of 2'-deoxyadenosine with glyoxal resulted in the formation of a previously not reported N6-(hydroxyacetyl)-2'-deoxyadenosine adduct. In the reaction of glyoxal with 2'-deoxycytidine and cytidine at neutral conditions and 37 degrees C, 5-hydroxyacetyl pyrimidine derivatives were obtained. When the cytidine reaction was performed at pH 4.5 and 50 degrees C, the 5-hydroxyacetyl derivative of uridine was formed through deamination of cytidine-glyoxal. Adducts in the thymidine reaction could not be detected. In the reaction of glyoxal with calf thymus DNA, the 2'-deoxyguanosine-glyoxal and 2'-deoxyadenosine-glyoxal adducts were obtained, the former being the major adduct.

Air formaldehyde and solvent concentrations during surface coating with acid-curing lacquers and paints in the woodworking and furniture industry

An investigation of contemporary exposure to formaldehyde and organic solvents has been carried out during surface coating with acid-curing lacquers and paints in the Norwegian woodworking and furniture industry over a period of 3 years. The investigation covered 27 factories of different sizes and with different types of production, and totally 557 parallel formaldehyde and solvent samples were collected. The formaldehyde concentration (geometric mean) was 0.15 ppm (range 0.01-1.48 ppm) with about 10% of the samples exceeding the Norwegian occupational exposure limit of 0.5 ppm. The solvent concentration as additive effect (geometric mean) was 0.13 (range 0.0004-5.08) and about 5% of the samples exceeded the Norwegian occupational exposure limit. The most frequently occurring solvents from acid-curing lacquers were n-butyl acetate, ethanol, ethyl acetate and 1-butanol, which were found in 88-98% of the samples. Toluene, n-butyl acetate and 1-butanol were the only solvents with maximum concentrations exceeding their respective occupational exposure limits. Curtain painting machine operators were exposed to the highest concentrations of both formaldehyde (geometric mean 0.51 ppm, range 0.08-1.48 ppm) and organic solvents (additive effect, geometric mean 1.18, range 0.02-5.08). Other painting application work tasks such as automatic and manual spray-painting, manual painting and dip painting, showed on average considerably lower concentrations of both formaldehyde (geometric means 0.07-0.16 ppm) and organic solvents (additive effect, geometric mean 0.02-0.18). Non-painting work tasks also displayed moderate concentrations of formaldehyde (geometric means 0.11-0.17 ppm) and organic solvents (additive effect, geometric mean 0.04-0.07).

Theoretical aspects of fluoride air contaminant formation in aluminium smelter potrooms

The amount of particulate fluorides evolved from aluminium electrolysis cells is not entirely accounted for by the fluorides entrained in the anode gas. The largest additional source of particulate fluoride formation is by direct evaporation of fluorides into the anode gas stream and subsequent condensation on the drops of electrolyte generated in the process of bubble burst. A theoretical model was used for the calculation of the main physical parameters responsible for the formation of particle nuclei when the hot anode-gas is mixed with ambient air. The results of these calculations are in agreement with experimental observations reported in the literature. In particular, the size distribution, composition and morphology of the nano-particles support the theory of a vapour condensation mechanism under conditions of extreme supersaturation, but further studies are necessary.

Characterization of individual aerosol particles in workroom air of aluminium smelter potrooms

Aerosol particles with aerodynamic diameters between 0.18 and 10 microm were collected in the workroom air of two aluminium smelter potrooms with different production processes (Soderberg and Prebake processes). Size, morphology and chemical composition of more than 2000 individual particles were determined by high resolution scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on chemical composition and morphology, particles were classified into different groups. Particle groups with a relative abundance above 1%(by number) include aluminium oxides, cryolite, aluminium oxides-cryolite mixtures, soot, silicates and sea salt. In both production halls, mixtures of aluminium oxides and cryolite are the dominant particle group. Many particles have fluoride-containing surface coatings or show agglomerations of nanometer-sized fluoride-containing particles on their surface. The phase composition of approximately 100 particles was studied by transmission electron microscopy. According to selected area electron diffraction, sodium beta-alumina (NaAl(11)O(17)) is the dominant aluminium oxide and cryolite (Na(3)AlF(6)) the only sodium aluminium fluoride present. Implications of our findings for assessment of adverse health effects are discussed.

Neuropsychological function in manganese alloy plant workers

OBJECTIVES

The objective was to investigate potential nervous system effects of manganese (Mn) exposure in workers employed in manganese-alloy-producing plants.

METHODS

One hundred male Mn alloy plant workers were compared with 100 age-matched referents. The subjects were examined with a comprehensive neuropsychological test battery. Exposure was assessed by measurement of Mn concentrations in the workroom air, blood and urine.

RESULTS

The geometric mean (GM) concentration of inhalable Mn in workroom air was 301 microg/m(3). The GM concentration of Mn in whole blood (181 nmol/l vs 160 nmol/l) ( P=0.002) and urine (0.9 nmol/mmol creatinine vs 0.4 nmol/mmol creatinine) ( P<0.001) was higher among the exposed subjects than among the referents. The Mn-exposed subjects had increased postural tremor while conducting a visually guided tremor test (static steadiness test) compared with the referents (mean number of contacts 94 vs 59 ( P= 0.001); duration of contacts (in seconds) 5.1 vs 3.5 ( P=0.003)). The tremor had larger frequency dispersion, indicating that the tremor included a wider variety of frequencies, among the exposed subjects than among the referents, assessed by the "TREMOR" test system. Smoking habits (self-reported) influenced the tremor parameters significantly, the Mn-exposed smokers having more tremor than the non-smoking Mn-exposed subjects. No differences between the groups were found in tests for cognitive functions, reaction time or in symptom reporting.

CONCLUSION

The Mn-exposed subjects had increased hand tremor compared with their referents. The tremor was related to exposure parameters. Smoking habits (self-reported) influenced the tremor parameters.

Iron status in manganese alloy production workers

The aim of this study was to investigate markers of iron status in production workers with current and long-term exposure to manganese (Mn) alloys. A total of 100 Mn-exposed male workers were compared with 100 male controls matched for age in a cross-sectional study. The geometric mean urinary Mn concentration in the exposed workers was 0.9 nmol mmol(-1) creatinine (range = 0.1-126.3), compared with 0.4 nmol mmol(-1) creatinine (range = 0.1-13.1) in the controls. The index group had been exposed to Mn for 20 years on average (range = 2.1-41.0). The geometric mean concentration of soluble transferrin receptor was lower in the exposed subjects than in the controls (2.2 vs 2.6 mg l(-1); P < 0.001) and the concentration was negatively associated with current exposure to "soluble" Mn in the inhalable aerosol fraction and with current smoking habits. An association was found between the concentration of serum soluble transferrin receptor and the concentration of Mn in whole blood (Pearson's r = 0.48; P < 0.001) in the controls. The results suggest that Mn-exposed workers have higher intracellular iron concentration in the erythrocyte precursors than the controls, resulting in a down-regulation of transferrin receptors on the surface of these cells. The concentrations of Mn in the blood of occupationally non-exposed individuals appear to be influenced by iron status, even at physiological iron levels.

Endocrine and immunologic markers in manganese alloy production workers

OBJECTIVES

The aim of this study was to investigate selected hormones and immunologic markers in manganese alloy production workers with current and long-term manganese exposure.

METHODS

One hundred randomly selected male workers exposed to manganese were compared with 100 male referents (matched for age) from similar process industries in a cross-sectional design.

RESULTS

The geometric mean of the exposed workers' urinary manganese concentration was 0.9 (range 0.1-126.3) nmol/mmol creatinine (Cr) versus 0.4 (range 0.1-13.1) nmol/mmol Cr for the referents. The mean duration of exposure to manganese was 20.0 (range 2.1-41.0) years. The geometric mean of the prolactin serum concentration was higher for the exposed subjects than for the referents (229 versus 197 mIE/l, P=0.06). Serum prolactin was associated with current exposure to "soluble inhalable manganese", duration of exposure, and smoking habits. The subjects with the longest duration of exposure to manganese or the highest current exposure to "soluble inhalable manganese" had a statistically significantly higher serum prolactin concentration than the referents. The smokers had a lower serum prolactin concentration than the nonsmokers. The concentrations of the measured immunologic markers were similar in the groups.

CONCLUSIONS

The study indicates that manganese exposure can increase the serum prolactin concentration. Both duration and current level of exposure are related to the slight increase, which also appears to be modified by current smoking habits. The serum prolactin concentrations were generally within the reference limits of the laboratory and thus not suitable as an exposure marker at these exposure levels.

Occupational exposure to fluorinated hydrocarbons during refrigeration repair work

This study describes refrigeration repair workers' occupational exposures to halogenated refrigerants, focusing on difluorochloromethane (HCFC 22), tetrafluoroethane (HFC 134a) and a mixture of tri-, tetra- and pentafluoroethane (R404A) in 30 work operations. Unlike earlier reported studies, the present study includes working procedures involving welding in order to measure possible occupational exposure to decomposition products. The measurements included hydrogen fluoride (HF), hydrogen chloride (HCl), phosgene (COCl2) and volatile organic compounds (VOC). The exposures were assessed during work operations on small-scale cooling installations like refrigerators and freezers. The repair workers' occupational exposures to refrigerants were moderate, and the major part of the exposures were associated with specific working procedures lasting for relatively short periods of time (<20 min). During these exposure events the concentrations were occasionally high (up to 42434 mg m(-3)). Although welding operations lasted only for short periods of time, HF was detected in 9 out of 15 samples when HCFC 22, HFC 134a or R404A had been used. Hydrogen chloride was detected in 3 out of 5 samples in air polluted with HCFC 22. Phosgene was not detected. A large number of VOCs in various concentrations were found during welding. Except for the applied refrigerants, halogenated compounds were only found in one sample.

Manganese air exposure assessment and biological monitoring in the manganese alloy production industry

One hundred workers carried personal air sampling equipment during three days to assess exposure to inhalable and respirable Mn. A novel four-step chemical fractionation procedure developed for the speciation of Mn in workroom aerosols was applied for selected aerosol filters. Blood and urine samples were analysed for Mn. The geometric mean (GM) concentrations of inhalable (n = 265) and respirable (n = 167) Mn determined in all filters were 254 microg m(-3) and 28 microg m(-3) respectively. Only 10.6% (95% CI 8.9-12.5) respirable Mn was found in the inhalable fraction when inhalable and respirable samples collected in parallel were considered (n = 153 pairs). There was a high correlation (Pearson's r = 0.70; p < 0.001) between respirable and inhalable Mn. The largest amounts of Mn in the inhalable aerosol fraction were found as Mn0 and Mn2+ (47.4%), whereas 28% was practically "insoluble". The associations between B-Mn and aerosol concentrations of Mn were weak, but an association was found between U-Mn and respirable Mn; Pearson's r being 0.38 between "soluble" respirable Mn and U-Mn. No significant association was found between the "insoluble" components (probably SiMn) and Mn in biological samples.

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.

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.

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.

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.

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.

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.

A Neuropsychological Study of Patients Exposed to Organic Solvents

Sixty-seven male patients exposed to organic solvents were neurospychologically examined. Twenty-five subjects had possible causes of encephalopathy other than solvent exposure, leaving 42 patients for the study of the association between exposure and neuropsychological test results. The patients had been heavily exposed for, on average, 24.6 years (range 2-46). The main clinical findings were impairments of psychomotor function, short-term memory, and attention. The results suggest an association between impaired psychomotor speed and exposure duration (r = 0.41; p = 0.007), with moderate to severe impairment occurring after at least 15 years. Forty percent of the patients exposed for more than 30 years had moderate to severely impaired psychomotor speed. The results suggest declining test performance on Trail Making Test B related to exposure duration (r = -0.34; p = 0.03). Further, the individual age-adjusted score on the Digit Span task (WAIS) was reduced when compared with the individual age-adjusted score on the Picture Completion task (WAIS). This reduction was related to exposure duration (r = -0.48; p = 0.002).

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.

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.

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).

An immunological study of chloralkali workers previously exposed to mercury vapour

Several animal studies have suggested that exposure to inorganic mercury compounds may have effects on the immune system. Human data are, however, relatively sparse. The presence of several autoantibodies and the concentration of immunoglobulins and complement components were determined in the present cross-sectional study in 77 chloralkali workers previously exposed to mercury vapour and 53 age-matched referents. The mean duration of exposure to mercury vapour was 7.9 years (range 1.1-36.2), and the exposure had ceased on average 12.3 years (range 1.0-35.0) prior to the examination. No increased prevalence of the studied autoantibodies was observed among the exposed subjects as compared with the referents. There were no significant differences in the concentrations of immunoglobulins or complement components between the two studied groups. Nor was any relationship observed between cumulative mercury dose estimates or time since cessation of exposure and the measured concentrations of immunoglobulins or complement components.

A neurological and neurophysiological study of chloralkali workers previously exposed to mercury vapour

Neurological and neurophysiological examinations were conducted in 77 former chloralkali workers previously exposed to mercury vapour and 53 referents. The exposure had ceased on average 12.3 years prior to the study. There was a higher prevalence of reduced distal sensation (13.0% vs 1.9%), postural tremor (18.2% vs 7.5%) and impaired coordination (10.4% vs 1.9%) among the exposed subjects as compared to the referents. Abnormal Romberg's test (6.5% vs 0%) and line walking (7.8% vs 0%) were also more prevalent. The first negative peak in visual evoked response (N75) was bilaterally prolonged, and the median motor (55.9 m/s vs 58.0 m/s) and sensory nerve conduction velocity (55.6 m/s vs 59.0 m/s) were slightly reduced among the highly exposed subjects. The results indicate that slight neurological abnormalities, which in most cases could not be classified as disease, may persist many years after exposure cessation.

Chromosome aberrations in chloralkali workers previously exposed to mercury vapor

Chromosome aberrations and micronuclei in peripheral lymphocytes were studied in 29 male chloralkali workers previously exposed to mercury vapor and in two matched reference groups comprising 29 nitrate fertilizer workers and 29 customs and police officers. The study was performed using whole-blood cultures with and without hydroxyurea and caffeine to inhibit deoxyribonucleic acid synthesis and repair, respectively. No significant differences in the frequencies of chromosome aberrations and micronuclei were observed. However, a nonsignificant increase in chromosome breaks and dicentrics was found in the subgroups with high urinary mercury peak levels or high cumulative mercury exposure. An increased prevalence of "high" scores of chromatid breaks in the inhibited cultures, exceeding the 75th percentile of all of the subjects studied, was observed for the chloralkali workers when compared with both reference groups. No evident cytogenetic effects were observed among the chloralkali workers with the methods used in the present study.

Incidence of cancer and mortality among workers exposed to mercury vapour in the Norwegian chloralkali industry

Incidence of cancer and mortality were studied among 674 men exposed to mercury vapour for more than one year at two chloralkali plants. Mercury excretion in urine had been monitored among the workers at the two plants since 1948 and 1949. An individual cumulative urinary mercury dose was calculated, based on about 20,000 urinary mercury measurements. The incidence of cancer and the mortality were followed up from 1953 to 1989 and 1953 to 1988 respectively. The general Norwegian male population served as a reference population. There was a lung cancer excess of borderline significance (standardised incidence ratio = 1.66, 95% confidence interval = 1.00-2.59). The introduction of a 10 year latent period before developing lung cancer did not increase the incidence ratio. The excess may be partly explained by the smoking habits in the cohort or possibly by exposure to asbestos. No excess of cancer was found in the target organs for mercury toxicity--namely, the kidney and the nervous system. No significant excess mortality was found for nephritis and nephrosis or nonmalignant diseases of the nervous system.

Urinary mercury excretion in chloralkali workers after the cessation of exposure

Seventeen former chloralkali workers were followed through the regular determination of urinary mercury for nearly two years after the cessation of exposure to mercury vapor in a study of the time course of urinary mercury elimination. Their duration of exposure ranged from 3 d to 35.5 years. A one-compartment model for urinary mercury elimination was applied. The urinary mercury concentration declined at a rate indicating a half-time of 91 d. When corrected for an individual base-line level of urinary mercury resulting from sources of mercury intake not related to work, the half-time was 72.4 [95% confidence interval (95% CI) 63.2-81.7] d, with a mean elimination rate constant of 0.011 (95% CI 0.008-0.013).d-1. The day-to-day variability of the urinary mercury concentration averaged 22%, expressed as the coefficient of variation between urine samples delivered on three consecutive days.

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.

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

The concentrations of total mercury (B-Hg), inorganic mercury (B-IHg), and methyl mercury (B-MeHg) in whole blood, urinary mercury (U-Hg), and selenium in urine (U-Se) and whole blood (B-Se) were determined in 74 chloralkali workers previously exposed to Hg vapour, and compared with 51 age matched referents. Dental amalgam state, fish consumption, and exposure related indices were studied with regard to the determined elements. A significant relation between the surface of dental amalgam and U-Hg (Pearson's r = 0.63, p < 0.001) was found among the referents. Mean U-Se was significantly lower (p < 0.001) among the subjects previously exposed to Hg (34.1 nmol/mmol creatinine) compared with that for the referents (42.6 nmol/mmol creatinine). A significant negative relation between the cumulative Hg dose and U-Se was also found. The mechanisms and the clinical significance of these findings are not clear. No relation between current U-Hg and previous occupational exposure to Hg was found among subjects in whom exposure had ceased more than one year before the study.

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.

Patients with suspected solvent-induced encephalopathy examined with cerebral computed tomography

The aim of this study was to investigate the relationship between organic solvent exposure and brain atrophy among 85 patients referred to a department of occupational medicine and who underwent cerebral computed tomography. On average, the patients had been heavily exposed to a mixture of organic solvents for 22.9 years. Diseases which may be associated with brain atrophy or high alcohol consumption was observed among 31% of the subjects. Among these subjects the prevalence of brain atrophy was 58%. The prevalence of brain atrophy was 20% among the men without such conditions. None of the eight female patients appeared to have atrophy. The quantitative assessment showed no correlation between the duration of exposure and atrophy-related parameters. However, the width of the third ventricle, bifrontal ratio, and bicaudate ratio were correlated with age.