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.

Neurosensory component of hand-arm vibration syndrome: a 22-year follow-up study.

BACKGROUND: Knowledge about the long-term course of the neurologic component of hand-arm vibration syndrome (HAVS) is scarce. AIMS: To study the course and prognostic factors of the neurosensory component of HAVS over a period of 22 years. METHODS: Forty male sheet metal workers, with a mean age of 60 (range 45-78) years at follow-up, were examined with a test battery in 1994 and 2017. At baseline, the sample comprised 27 workers with HAVS symptoms and 13 workers without HAVS symptoms. Among the 27 workers, 25 workers reported work-related hand-arm vibration during follow-up (mean 3639 h). In 2017, the mean time since vibration stopped was 8.4 years. RESULTS: Among the 27 workers with HAVS in 1994, no overall statistically significant change was observed in hand numbness (Stockholm Workshop Scale), shoulder/arm pain (pain scale) or finger pain from 1994 to 2017. However, vibration exposure during follow-up was associated with increased finger pain. Cotinine, carbohydrate-deficient transferrin, glycosylated haemoglobin and folate were not associated with changes in neurosensory symptoms or manual dexterity (Grooved Pegboard) from 1994 to 2017. A diagnosis of HAVS in 1994 did not predict poor hand strength 22 years later. Isolated hand numbness (without white finger attacks) was more common at baseline than at follow-up. CONCLUSIONS: This 22-year follow-up study indicates a tendency towards irreversibility of hand numbness and finger pain in workers with HAVS. Continued vibration exposure seems to predict increased finger pain. Our findings highlight the importance of HAVS prevention.

Vascular component of hand-arm vibration syndrome: a 22-year follow-up study.

BACKGROUND: Vibration-induced white finger (VWF) is often assessed using the Stockholm Workshop Scale (SWS) and cold challenge plethysmography. However, long-term longitudinal studies using both methods are scarce. AIMS: To study the long-term course and prognostic factors of VWF assessed with the SWS and photoplethysmography (PPG), and to examine the effects of lifestyle on PPG score, regardless of VWF status. METHODS: Forty male construction workers were examined with a test battery and clinical examination in 1994 and 2016/17. RESULTS: At baseline, the sample comprised 27 workers with, and 13 without, symptoms of hand-arm vibration syndrome (HAVS). Thirty-five workers reported vibration exposure during follow-up. The mean age of the workers was 60 years (45-78) at follow-up. The paired t-test showed that PPG scores deteriorated from 1994 to 2017 in the 27 workers with HAVS in 1994 (mean difference 2.7 min, 95% confidence interval (CI) 0.2-5.2). However, there was no statistically significant change in SWS scores in these workers over time. Smoking and age were associated with PPG score deterioration. Vibration exposure during follow-up predicted SWS score deterioration: 1000 h of exposure predicted a deterioration stage of 0.09 (95% CI 0.03-0.16). Analysis of all 40 workers showed that 2017 PPG scores were associated with positive serum cotinine and self-reported smoking during follow-up. CONCLUSIONS: Whereas age and smoking predicted a PPG deterioration, continued vibration exposure predicted worsening of white finger symptoms. The association of PPG score and smoking should be considered in diagnostic and prognostic factor evaluations.

Systematic review of the cardiovascular effects of occupational noise.

BACKGROUND: Cross-sectional studies of occupational noise and cardiovascular effects show an association between noise and hypertension but for coronary heart disease or other cardiovascular diseases (CVDs) the evidence is not convincing. AIMS: To assess possible associations between occupational noise exposure and the risk for cardiovascular effects in follow-up studies published after 1999. METHODS: We performed a systematic critical literature review of original articles from key literature databases of associations between workplace noise and health. The studies were identified by search in Ovid Medline, Ovid Embase, Web of Science, Scopus and ProQuest Health and Safety Sciences Abstracts. We selected prospective studies of adequate quality with a measure of association between occupational noise exposure and cardiovascular health for the meta-analysis. RESULTS: Twelve papers, all prospective and mostly with high quality but with methodological shortcomings in exposure assessment, were included in the review and meta-analysis. Exposure to noise at work was consistently positively associated with hypertension [Hazard ratio (HR) = 1.68; 95% confidence interval (CI) 1.10-2.57] and CVD [relative risk (RR) = 1.34; 95% CI 1.15-1.56]. In addition, we found a trivial effect of noise exposure on CVD mortality (HR = 1.12; 95% CI 1.02-1.24). CONCLUSIONS: Occupational noise exposure is strongly associated with hypertension. For other cardiovascular effects, this meta-analysis suggests a weak association, but the evidence is limited. More longitudinal studies on the effects of occupational noise on the cardiovascular system are warranted.

Exposure to thoracic dust, airway symptoms and lung function in cement production workers.

Cement dust exposure has previously been associated with airway symptoms and ventilatory impairment. The aim of the present study was to examine lung function and airway symptoms among employees in different jobs and at different levels of exposure to thoracic dust in the cement production industry. At the start of a 4-yr prospective cohort study in 2007, exposure to cement dust, symptoms and lung function were recorded cross-sectionally in 4,265 employees in 24 European cement plants. Bronchial exposure was assessed by 2,670 full-shift dust samples with cyclones collecting the thoracic aerosol fraction. A job exposure matrix was constructed by grouping dust concentrations according to job type and plant. Elevated odds ratios for symptoms and airflow limitation (range 1.2-2.6 in the highest quartile), but not for chronic bronchitis, were found in the higher quartiles of exposure compared with the lowest quartile. Forced expiratory volume in 1 s (FEV(1)) showed an exposure-response relationship with a 270-mL deficit of FEV(1) (95% CI 190-300 mL) in the highest compared with the lowest exposure level. The results support the hypothesis that exposure to dust in cement production may lead to respiratory symptoms and airway obstruction.

Determinants of microbial exposure in grain farming.

OBJECTIVES: Exposure to organic dust containing high concentrations of microorganisms is common in grain farming, although the farmers have practices to counteract microbial growth to obtain optimal grain yields. We investigated the influence of weather and production practices on personal microbial exposure during grain work. METHODS: Airborne dust was collected by personal sampling during threshing and storage work on 92 Norwegian farms. The personal exposure for bacteria, endotoxin, fungal spores and hyphae, beta-(1-->3)-glucans and actinomycetes was quantified and compared with climatic data expressed as fungal forecasts from the grain growth season and production practices as reported by farmers. RESULTS: Farmers were exposed to a geometrical mean of 4.4 mg m(-3) inhalable dust [geometrical standard deviation (GSD) = 4.0], 4 x 10(6) m(-3) bacteria and fungal spores (GSD = 5.2 and 5.9, respectively), 5.9 x 10(3) EU m(-3) of endotoxins (GSD = 8.6), 2 x 10(5) m(-3) actinomycetes (GSD = 15.3), 120 mug m(-3) beta-(1-->3)-glucans (GSD = 4.7) and 5 x 10(5) AU m(-3) of hyphae (GSD = 4.4). Univariate associations were found between one or several of these microbial factors and work operation, visible fungal damage, grain species, lodging of grain, storage technology or harvester type. As assessed by general linear models, storage work was the main predictive determinant for microbial exposure, although grain species and visible fungal damage also were also important. Wet and warm weather throughout the grain growth season were associated with elevated exposure for inhalable dust, beta-(1-->3)-glucans, endotoxins and hyphae during threshing. The beta-(1-->3)-glucan exposure could biologically be explained by the fungal spore and hyphal exposure, both variables contributing equally. However, spores were most important during storage work, whereas only hyphae were predictive during threshing. CONCLUSIONS: Farmers were exposed to high levels of microorganisms and their components during dusty grain work. Dust prevention and protection may reduce microbial exposure, and may be particularly important in areas with frequent fungal forecasts, when fungal damage has been observed, during storage work or when handling barley.

Incidence of lip cancer in the male Norwegian agricultural population.

OBJECTIVE: To explore lip cancer (LC) associations with work environmental exposures in a record-linkage study of Norwegian farmers. We hypothesize immunosuppressive substances (e.g. mycotoxins, pesticides) to influence LC incidence. METHODS: A cohort of 131,243 male Norwegian farmers born 1925-1971 was established by cross-linkage of national registers and followed up through 1999 for incident LC, (ICD-7 site 140) in the Cancer Registry of Norway. Farm production data from agricultural censuses 1969-1979 and meteorological data on solar radiation and fungal forecasts (events of wet and temperate conditions known to favour fungal growth and mycotoxin formation) served as exposure proxies. Adjusted rate ratios (RR) and 95% confidence intervals (CI) were estimated using Poisson regression. RESULTS: We identified 108 LC cases (rate 4.4 per 100,000 person-years). We found LC to be moderately associated with horses on the farm (RR = 1.6, CI = 1.0-2.4), construction work employment (RR = 1.7, CI = 1.1-2.6), pesticide use (RR = 0.7, CI = 0.4-1.0), grain production (RR = 1.3, CI = 0.9-2.1) and increasing levels of fungal forecasts (RR = 1.6, CI = 0.9-2.8 in the highest two quartiles). CONCLUSION: Moderate associations of LC with grain production and fungal forecasts and the negative association with pesticide could possibly be explained by exposure to immunosuppressive mycotoxins. Some of the associations observed could be explained by solar exposure.