BACKGROUND: Trihalomethanes (THMs) are widespread disinfection by-products (DBPs) in drinking water, and long-term exposure has been consistently associated with increased bladder cancer risk. OBJECTIVE: We assessed THM levels in drinking water in the European Union as a marker of DBP exposure and estimated the attributable burden of bladder cancer. METHODS: We collected recent annual mean THM levels in municipal drinking water in 28 European countries (EU28) from routine monitoring records. We estimated a linear exposure-response function for average residential THM levels and bladder cancer by pooling data from studies included in the largest international pooled analysis published to date in order to estimate odds ratios (ORs) for bladder cancer associated with the mean THM level in each country (relative to no exposure), population-attributable fraction (PAF), and number of attributable bladder cancer cases in different scenarios using incidence rates and population from the Global Burden of Disease study of 2016. RESULTS: We obtained 2005-2018 THM data from EU26, covering 75% of the population. Data coverage and accuracy were heterogeneous among countries. The estimated population-weighted mean THM level was 11:7 lg=L [standard deviation (SD) of 11.2]. The estimated bladder cancer PAF was 4.9% [95% confidence interval (CI): 2.5, 7.1] overall (range: 0-23%), accounting for 6,561 (95% CI: 3,389, 9,537) bladder cancer cases per year. Denmark and the Netherlands had the lowest PAF (0.0% each), while Cyprus (23.2%), Malta (17.9%), and Ireland (17.2%) had the highest among EU26. In the scenario where no country would exceed the current EU mean, 2,868 (95% CI: 1,522, 4,060; 43%) annual attributable bladder cancer cases could potentially be avoided. DISCUSSION: Efforts have been made to reduce THM levels in the European Union. However, assuming a causal association, current levels in certain countries still could lead to a considerable burden of bladder cancer that could potentially be avoided by optimizing water treatment, disinfection, and distribution practices, among other possible measures.
The objective of this study was to determine the incidence of nontuberculous mycobacteria (NTM) in hot water systems of 4 selected hospital settings. The hospitals provided the following types of disinfection for their hot water systems: hydrogen peroxide and silver, thermal disinfection, chlorine dioxide, and no treatment (control). In each building, 6 samples were collected from 5 sites during a 3 month period. NTM were detected in 56 (46.7%) of 120 samples; the CFU counts ranged from 10 to 1625 CFU/L. The detected NTM species were the pathogens Mycobacterium kansasii, Mycobacterium xenopi, and Mycobacterium fortuitum and the saprophyte Mycobacterium gordonae. The most common to be isolated was M. xenopi, which was present in 51 samples. The hot water systems differed significantly in the incidence of NTM. NTM were not detected in the system treated by thermal disinfection, and a relatively low incidence (20% positive samples) was found in the system disinfected with chlorine dioxide. However, a high incidence was found in the control system with no additional disinfection (70% positives) and in the system using hydrogen peroxide and silver (97% positives). Water temperatures above 50 degrees C significantly limited the occurrence of NTM.
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