Influence of ergonomic factors on peripheral neuropathy under HAV exposure.

BACKGROUND: Hand-arm vibration (HAV) is a risk factor for carpal tunnel syndrome (CTS) and ulnar neuropathy at the elbow (UNE). It is unclear how ergonomic factors influence the relationship between HAV exposure and CTS and UNE. AIMS: We aimed to assess the relationship between cumulative HAV exposure and CTS and UNE in workers exposed to HAV from two tools with different ergonomic profiles. METHODS: We performed nerve conduction studies (NCSs) of the sensory and motor median and ulnar nerves and recorded symptoms indicating CTS and UNE in workers exposed to HAV from impact wrenches or from rock drills. Exposure was measured as cumulative lifetime exposure. We used linear regression adjusted for age and body mass index to assess linear relationships. RESULTS: Sixty-five workers participated (33 rock drill and 32 impact wrench operators). We found inverse linear associations between cumulative HAV exposure and median nerve sensory conduction velocity in impact wrench operators and ulnar nerve motor conduction velocity in rock drill operators (beta of 0.63 and 0.75). Based on NCS findings and symptoms, seven impact wrench operators had CTS and one UNE, and four rock drill operators had CTS and six UNE. CONCLUSIONS: Our findings indicate that ergonomic factors influence the development of CTS and UNE under HAV exposure. The ergonomic profile seems to influence which type of neuropathy workers exposed to HAV will develop. Design of occupational exposure guidelines and future studies should be based on ergonomic profile and exposure characteristics for different tools and not merely HAV.

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.

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.

Respiratory symptoms and airflow limitation in asphalt workers.

BACKGROUND: Asphalt workers are exposed to bitumen fume and vapour, and to exhaust from engines and passing traffic. AIMS: To assess the occurrence of respiratory symptoms and signs of airflow limitations in a group of asphalt workers. METHODS: All 64 asphalt workers and a reference group of 195 outdoor construction workers from the same company participated in a cross-sectional study. Spirometric tests and a questionnaire on respiratory symptoms and smoking habits were administered. Respiratory symptoms and lung function were adjusted for age and smoking. RESULTS: The FEV1/FVC% ratio was significantly lower in the asphalt workers than in the referents. Symptoms of eye irritation, chest tightness, shortness of breath on exertion, chest wheezing, physician diagnosed asthma, and chronic obstructive pulmonary disease (COPD) were all significantly more prevalent among the asphalt workers. CONCLUSION: In asphalt workers there is an increased risk of respiratory symptoms, lung function decline, and COPD compared to other construction workers.

Cumulative exposure to dust and gases as determinants of lung function decline in tunnel construction workers.

AIMS: To study the relation between lung function decrease and cumulative exposure to dust and gases in tunnel construction workers. METHODS: A total of 651 male construction workers (drill and blast workers, tunnel concrete workers, shotcreting operators, and tunnel boring machine workers) were followed up by spirometric measurements in 1989-2002 for an average of six years. Outdoor concrete workers, foremen, and engineers served as a low exposed referent population. RESULTS: The between worker component of variability was considerably reduced within the job groups compared to the whole population, suggesting that the workers within job groups had similar exposure levels. The annual decrease in FEV1 in low-exposed non-smoking workers was 21 ml and 24 ml in low-exposed ever smokers. The annual decrease in FEV1 in tunnel construction workers was 20-31 ml higher than the low exposed workers depending on job group for both non-smokers and ever smokers. After adjustment for age and observation time, cumulative exposure to nitrogen dioxide showed the strongest association with a decrease in FEV1 in both non-smokers, and ever smokers. CONCLUSION: Cumulative exposure to nitrogen dioxide appeared to be a major risk factor for lung function decreases in these tunnel construction workers, although other agents may have contributed to the observed effect. Contact with blasting fumes should be avoided, diesel exhaust emissions should be reduced, and respiratory devices should be used to protect workers against dust and nitrogen dioxide exposure.

Increase in interleukin-6 and fibrinogen after exposure to dust in tunnel construction workers.

OBJECTIVES: To see if there is any change in blood concentrations of interleukin-6 (IL-6) and fibrinogen during a working shift in tunnel construction workers. METHODS: 12 Tunnel construction workers were followed up during a 24 hours period after returning from a 9 day work free period. The first blood sample was taken on Monday afternoon before starting the shift. Another was taken around midnight after 8 hours of work, and another the next afternoon after about 12 hours of rest. Exposure to respirable dust was measured by personal samplers. RESULTS: The exposure of the workers to respirable dust, in terms of an 8 hour time weighted average, varied between 0.3 and 1.9 mg/m(3). For IL-6, there was an increase in the median serum concentration from 1.14 ng/l before starting the shift to 4.86 ng/l after 8 hours of work (p=0.002). For fibrinogen, there was an increase in the median concentration from 3.40 g/l before entering the shift to 3.70 g/l 24 hours later (p=0.044). There was a positive correlation between values of IL-6 at the end of the working shift and the fibrinogen concentrations the next afternoon (Pearson's R=0.73, p=0.007). The observed increase in IL-6 was significant for both smokers and non-smokers. CONCLUSION: The study shows an increase in both IL-6 and fibrinogen concentrations during a working shift for both smoking and non-smoking tunnel construction workers.

Cumulative exposure to dust causes accelerated decline in lung function in tunnel workers.

OBJECTIVES: To examine whether underground construction workers exposed to tunnelling pollutants over a follow up period of 8 years have an increased risk of decline in lung function and respiratory symptoms compared with reference subjects working outside the tunnel atmosphere, and relate the findings to job groups and cumulative exposure to dust and gases. METHODS: 96 Tunnel workers and a reference group of 249 other heavy construction workers were examined in 1991 and re-examined in 1999. Exposure measurements were carried out to estimate personal cumulative exposure to total dust, respirable dust, alpha-quartz, oil mist, and nitrogen dioxide. The subjects answered a questionnaire on respiratory symptoms and smoking habits, performed spirometry, and had chest radiographs taken. Radiological signs of silicosis were evaluated (International Labour Organisation (ILO) classification). Atopy was determined by a multiple radioallergosorbent test (RAST). RESULTS: The mean exposure to respirable dust and alpha-quartz in tunnel workers varied from 1.2-3.6 mg/m3 (respirable dust) and 0.019-0.044 mg/m3 (alpha-quartz) depending on job task performed. Decrease in forced expiratory volume in 1 second (FEV1) was associated with cumulative exposure to respirable dust (p<0.001) and alpha-quartz (p=0.02). The multiple regression model predicted that in a worker 40 years of age, the annual decrease in FEV1 would be 25 ml in a non-exposed non-smoker, 35 ml in a non-exposed smoker, and 50-63 ml in a non-smoking tunnel worker (depending on job). Compared with the reference group the odds ratio for the occurrence of new respiratory symptoms during the follow up period was increased in the tunnel workers and associated with cumulative exposure to respirable dust. CONCLUSIONS: Cumulative exposures to respirable dust and alpha-quartz are the most important risk factors for airflow limitation in underground heavy construction workers, and cumulative exposure to respirable dust is the most important risk factor for respiratory symptoms. The finding of accelerated decline in lung function in tunnel workers suggests that better control of exposures is needed.

Dust and gas exposure in tunnel construction work.

Personal exposures to dust and gases were measured among 189 underground construction workers who were divided into seven occupational groups performing similar tasks in similar working conditions: drill and blast crew; shaft-drilling crew; tunnel-boring machine crew; shotcreting operators; support workers; concrete workers; and electricians. Outdoor tunnel workers were included as a low-exposed reference group. The highest geometric mean (GM) exposures to total dust (6-7 mg/m3) and respirable dust (2-3 mg/m3) were found for the shotcreters, shaft drillers, and tunnel-boring machine workers. Shaft drillers and tunnel-boring machine workers also had the highest GM exposures to respirable alpha-quartz (0.3-0.4 mg/m3), which exceeded the Norwegian occupational exposure limit (OEL) of 0.1 mg/m3. Shaft drillers had the highest exposure to oil mists (GM=1.4 mg/m3), which was generated mainly from pneumatic drilling. For other groups, exposure to oil mist from diesel exhaust and spraying of oil onto concrete forms resulted in exposures of 0.1-0.5 mg/m3. Exposure to nitrogen dioxide was similar across all groups (GM=0.4-0.9 ppm), except for shaft drillers and tunnel-boring machine workers, who had lower exposures. High short-term exposures (>10 ppm), however, occurred when workers were passing through the blasting cloud.

Effects of blasting fumes on exposure and short-term lung function changes in tunnel construction workers.

OBJECTIVES: This study attempts to determine the effects of exposure to blasting fumes and its influence on the lung function of tunnel workers. METHODS: Two groups of tunnel workers, one using ammonium nitrate fuel oil (ANFO) as the explosive and the other using size-sensitized emulsion (SSE), with 24 workers per group, were compared with a reference group (N=34) with low exposure. Spirometry was used to determine lung function. Personal exposure to total and respirable dust, alpha-quartz, volatile organic compounds, oil mist and vapors, formaldehyde, nitrogen dioxide, and carbon monoxide was measured. RESULTS: The ANFO workers were more exposed to all the agents than the reference group and more exposed than the SSE workers to all the agents except total dust and carbon monoxide. The SSE workers were significantly more exposed to total dust and alpha-quartz than the reference group. High peak exposures to nitrogen dioxide (up to 20 ppm) occurred for the ANFO workers in contrast to the SSE workers, whose exposure did not exceed 2 ppm. The lung function of the ANFO workers significantly decreased by 3% for forced vital capacity, 7% for forced expiratory volume in 1 second, and 8% for forced expiratory flow rate from 25% to 75% of the forced vital capacity over the 11-day period. The changes were reversible. There were no significant changes among the SSE workers and the outdoor workers. The ANFO workers had a significant decrease in FEV1.0 when compared with both the SSE and outdoor workers. CONCLUSIONS: Tunnel workers using ANFO explosive show a temporary reduction in lung function, whereas those using SSE do not. The most likely explanation for the observed changes is peak exposures to nitrogen dioxide.

Gas and dust exposure in underground construction is associated with signs of airway inflammation.

Exposure to gases and dust may induce airway inflammation. It was hypothesized that heavy construction workers who had been exposed to dust and gases in underground construction work for 1 yr, would have early signs of upper and lower airway inflammation, as compared to outdoor workers. A study group comprising 29 nonsmoking underground concrete workers (mean +/- SD age 44+/-12 yrs), and a reference group of 26 outdoor concrete workers (39+/-12 yrs) were examined by acoustic rhinometry, nasal and exhaled nitric oxide spirometry and a questionnaire on respiratory symptoms. Exposure measurements were carried out. The underground workers had higher exposure to total and respirable dust, alpha-quartz and nitrogen dioxide than the references (p<0.001). The occurrence of respiratory symptoms was higher in the underground workers than in the references (p<0.05). Exhaled nitric oxide (NO) (geometric mean+/-SEM) was higher in the underground workers than in the references (8.4+/-1.09 versus 5.6+/-1.07 parts per billion (ppb), p = 0.001), whereas spirometric values were comparable. The underground workers had smaller nasal cross-sectional area and volume than the references, and more pronounced increases after decongestion (p<0.001). To conclude the exposure in underground construction may cause nasal mucosal swelling and increased levels of exhaled nitric oxide, indicating signs of upper and lower airway inflammation.

Increased risk of obstructive pulmonary disease in tunnel workers.

BACKGROUND: Tunnel workers are exposed to gases and particles from blasting and diesel exhausts. The aim of this study was to assess the occurrence of respiratory symptoms and airflow limitation in tunnel workers and to relate these findings to years of exposure. METHODS: Two hundred and twelve tunnel workers and a reference group of 205 other heavy construction workers participated in a cross sectional investigation. Exposure measurements were carried out to demonstrate the difference in exposure between the two occupational groups. Spirometric tests and a questionnaire on respiratory symptoms and smoking habits were applied. Atopy was determined by a multiple radioallergosorbent test (RAST). Radiological signs of silicosis were evaluated. Respiratory symptoms and lung function were studied in relation to years of exposure and adjusted for smoking habits and atopy. RESULTS: Compared with the reference subjects the tunnel workers had a significant decrease in forced vital capacity (FVC) % predicted and forced expiratory volume in one second (FEV(1)) % predicted when related to years of exposure. Adjusted FEV(1) decreased by 17 ml for each year of tunnel work exposure compared with 0.5 ml in outdoor heavy construction workers. The tunnel workers also reported significantly higher occurrence of respiratory symptoms. The prevalence of chronic obstructive pulmonary disease (COPD) was 14% in the tunnel workers compared with 8% in the reference subjects. CONCLUSION: Exposure to dust and gases from diesel exhaust, blasting, drilling and rock transport in tunnel work enhances the risk for accelerated decline in FEV(1), respiratory symptoms, and COPD in tunnel workers compared with other heavy construction workers.

Asthma in tunnel workers exposed to synthetic resins.

OBJECTIVES: The prevalence of asthma among tunnel workers exposed to synthetic resins was studied by determining airway symptoms, methacholine responsiveness, and lung function. METHODS: Nineteen injection workers were compared with a group of 104 other tunnel workers with similar exposure, except for that to synthetic resins. A questionnaire on respiratory symptoms, smoking habits, use of respiratory protection, and work tasks was used. Lung function was studied using a bellows spirometer. Bronchial reactivity was tested with methacholine. Allergy screening with Phadiatop and radioallergosorbent tests for toluene-diisocyanate-HSA, diphenylmethane-4.4-diisocyanate-HSA, and formaldehyde-HSA (HSA = human serum albumin) were carried out. Methylene diphenyl diisocyanate (MDI) and MDI prepolymer exposure was estimated by filter sampling, and the filters were analyzed by high-performance liquid chromatography. The most common work situations were simulated for an estimation of exposure to isocyanates. RESULTS: The injection workers reported more respiratory symptoms than the reference group, and they had higher prevalences of bronchial hyperresponsiveness (37% versus 14%), asthma (26% versus 1%), and airflow limitation (37% versus 4%). Toluene-diisocyanate-HSA-specific immunoglobulin E antibodies were found in 2 of the 19 injection workers, but in none of the other tunnel workers. By simulation at a worksite, the average exposure to polymerized MDI was estimated to be 5.5-300 microg/m3 during injection work and 18-4300 microg/m3 during short-term exposure, the highest exposure occurring when cured polyurethane was ground. CONCLUSIONS: Exposure to partly decomposed MDI in tunnel work enhances the risk for respiratory symptoms, methacholine hyperresponsiveness, asthma, and airflow limitation.