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Manganese exposure and cardiovascular responses among welders.
Silver Spring, MD: Center to Protect Workers' Rights, 2010 Jul; :1-18
Welders are exposed to relatively high concentrations of manganese (Mn) and while the neurotoxicity of Mn is well documented, few studies have investigated the cardiac effects of occupational Mn exposures. The goal of this study was to investigate the cardiac effects of Mn exposures among welders, specifically boilermaker construction workers, using a repeated measures study design where workers were monitored twice or more over a 6-month period. A total of 78 male welders were recruited from a union hall out of Quincy, MA. In total, 118 worker-days were collected with 28 (36 percent) workers monitored at two or more time points. Blood, hair, and nail samples were collected as biomarkers of Mn exposure (Table 1). Hair samples were only available on 33 percent of participants due to short hair. Detailed work histories were collected to calculate a Mn cumulative exposure index (CEI). The cardiovascular health of each worker was assessed by ambulatory electrocardiogram (ECG) and inflammatory markers. A sub-study of 49 welders with toenail, blood and work history collected at one time-point was used to determine the relationship between blood and toenail Mn and CEI. Collected toenail samples had a skewed distribution ranging from 0.05 to 10.41 ng/g with a median of 0.80 ng/g (25th-75th percentiles: 0.45-1.49) (Table 2). Toenail Mn increased with the Mn-CEIs for the exposure windows between 7 and 12 months prior to the toenail clipping date. These results were confirmed when the Spearman correlations between toenail Mn and past Mn-CEI, adjusted for age and dietary Mn intake, were evaluated (Table 3). Biomarker and cardiovascular health endpoints analysis is ongoing. We hypothesize that occupational exposure to Mn will be associated with detectable changes in cardiovascular autonomic control as assessed by 24-hr heart rate variability (HRV) as well as changes in inflammatory markers as assessed by C - reactive protein and fibrinogen. The top findings from this pilot study are: 1. Toenails provide a useful biomarker of intermediate Mn exposures. Our study demonstrates that toenail Mn, averaged over clippings from all 10 toes, is correlated with Mn-CEI windows encompassing months 7-12 before the toenail clipping date. 2. Toenail and blood Mn concentration showed no correlation and likely represent different exposure windows. 3. Boilermaker construction workers with variable Mn exposure have detectable blood and toenail manganese concentrations. 4. Toenail and blood samples are easily provided by welders while hair samples are difficult to collect. 5. We were able to recruit 78 individuals into our study over the 18-month period. However, due to variable work schedules, it was difficult to monitor participants more than once (only 36 percent). Future studies should account for the variable work schedule among boilermaker construction workers.
Construction; Construction-materials; Construction-workers; Construction-equipment; Welders; Welding; Welding-equipment; Welding-industry; Manganese-compounds; Exposure-assessment; Cardiac-function; Cardiovascular-system; Boiler-furnaces; Biological-monitoring; Medical-monitoring; Men; Medical-examinations; Biomarkers; Worker-health; Cardiovascular-function; Cardiovascular-function-tests; Electrocardiography; Blood-samples; Blood-sampling; Sampling
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Construction; Cooperative Agreement
Manganese Exposure and Cardiovascular Responses Among Welders
CPWR-The Center for Construction Research and Training, Silver Spring, Maryland