Using exposure windows to explore an elusive biomarker: blood manganese

• Published in: International archives of occupational and environmental health Vol. 89; no. 4; pp. 679 - 687
• Main Authors: Baker, Marissa G., Stover, Bert, Simpson, Christopher D., Sheppard, Lianne, Seixas, Noah S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2016; Springer Nature B.V
• Subjects: Adult; Air Pollutants, Occupational - blood; Biomarkers; Biomarkers - blood; Blood; Earth and Environmental Science; Environment; Environmental Health; Exposure; Female; Heavy metals; Human exposure; Humans; Male; Manganese; Manganese - blood; Occupational Exposure - analysis; Occupational health; Occupational Medicine/Industrial Medicine; Original Article; Rehabilitation; Time Factors; Welding; Welding - methods; Biomarker of exposure; Welding; Exposure windows; Exposure modeling; Exposure assessment; Manganese
• ISSN: 0340-0131; 1432-1246
• DOI: 10.1007/s00420-015-1105-3

Purpose We sought to understand the time course between exposure to manganese (Mn) and uptake into the blood, to allow a more meaningful interpretation of exposure biomarker data, and to determine the utility of blood as a biomarker of Mn exposure. Methods Welder trainees were monitored over the course of a five-quarter training program. Each quarter, trainees gave eight blood samples and had personal air monitoring four times. A mixed model was fit to obtain estimates of airborne exposure by welding type (fixed effect), adjusted for subject (random effect). Considering weekends and days absent as zero exposure, estimated exposures were summed over various exposure windows and related to measured blood manganese (MnB) using a mixed model. Results A relationship consistent with zero was found between MnB and modeled 1 or 7 days of exposure. After 30 days of preceding exposure, a 1 mg-days/m 3 increase in air Mn is associated with a 0.57 ng/mL increase in MnB (95 % CI −0.04, 1.19). Considering a 90-day exposure window and a cumulative exposure window, a 1 mg-days/m 3 increase in air Mn is associated with a 0.26 (95 % CI 0.005, 0.51) and 0.09 (95 % CI 0.006, 0.17) ng/mL increase in MnB, respectively. Conclusions From this analysis, MnB may begin to act as a biomarker of Mn exposure over longer time periods, or at higher levels of exposure. This novel study design allowed investigation of how MnB relates to different time windows of exposure, representing the most robust Mn exposure assessment in the biomarker literature.