Biomarkers of end of shift exposure to disinfection byproducts in nurses

Increased disinfectant use commonly takes place in hospitals and other health care settings. A cross-sectional study among active nurses in two Cypriot public hospitals（n = 179） was conducted to examine the prevalence of exposure to disinfection byproducts（DBPs）, such as trihalomethanes（THMs） using both self-reported information and biomarker measurements.The objectives of this study were to： i） quantify the magnitude and variability of occupational exposure to disinfectants/DBPs in nurses, ii） generate job exposure matrices（JEM） and job task exposure matrices（JTEM） for disinfectants, and iii） assess the major determinants of urinary THMs in nurses. End of shift urinary total THM values showed high variability among the nurses, but did not differ between hospitals. The disinfectant group of alcohols/phenols was used by 〉 98% of nurses, followed by octenidine（82%）, iodine and chlorine（39%, each）,chlorhexidine（25%）, formaldehyde（12%）, hydrogen peroxide（11%）, and peracetic acid/ammonia/quaternary ammonium compounds（QACs）, all being 〈 8% each. Chlorine use during the past 24 hr was associated with significantly（p 〈 0.05） lower brominated THMs（Br THMs） after adjusting for age, gender and BMI, while a positive association was shown for TCM and the sum of all THMs（TTHMs）, albeit not significant. Nurses were exposed to nearly double the levels of TTHMs and BrT HMs（median and IQR, 1027 [560, 2475] ng/g and 323 [212,497] ng/g, respectively） when compared to those of the general population（552 [309,989] ng/g and 152 [87,261] ng/g, respectively）. This was the first occupational health dataset reporting measurements of biomarkers of end of shift exposures to disinfectants/DBPs.

Case study approach to modeling historical disinfection by-product exposure in Iowa drinking waters

In the 1980 s, a case–control epidemiologic study was conducted in Iowa（USA） to analyze the association between exposure to disinfection by-products（DBPs） and bladder cancer risk. Trihalomethanes（THMs）, the most commonly measured and dominant class of DBPs in drinking water, served as a primary metric and surrogate for the full DBP mixture.Average THM exposure was calculated, based on rough estimates of past levels in Iowa. To reduce misclassification, a follow-up study was undertaken to improve estimates of past THM levels and to re-evaluate their association with cancer risk. In addition, the risk associated with haloacetic acids, another class of DBPs, was examined. In the original analysis, surface water treatment plants were assigned one of two possible THM levels depending on the point of chlorination. The re-assessment considered each utility treating surface or groundwater on a case-by-case basis. Multiple treatment/disinfection scenarios and water quality parameters were considered with actual DBP measurements to develop estimates of past levels. The highest annual average THM level in the re-analysis was156 μg/L compared to 74 μg/L for the original analysis. This allowed the analysis of subjects exposed at higher levels（〉 96 μg/L）. The re-analysis established a new approach, based on case studies and an understanding of the water quality and operational parameters that impact DBP formation, for determining historical exposure.