Abstract
The formation of potentially carcinogenic N-nitrosamines, associated with monochloramine, requires further research due to the growing interest in using this biocide for the secondary disinfection of water in public and private buildings. The aim of our study was to evaluate the possible formation of N-nitrosamines and other toxic disinfection by-products (DBPs) in hospital hot water networks treated with monochloramine. The effectiveness of this biocide in controlling Legionella spp. contamination was also verified. For this purpose, four different monochloramine-treated networks, in terms of the duration of treatment and method of biocide injection, were investigated. Untreated hot water, municipal cold water and, limited to N-nitrosamines analysis, hot water treated with chlorine dioxide were analyzed for comparison. Legionella spp. contamination was successfully controlled without any formation of N-nitrosamines. No nitrification or formation of the regulated DBPs, such as chlorites and trihalomethanes, occurred in monochloramine-treated water networks. However, a stable formulation of hypochlorite, its frequent replacement with a fresh product, and the routine monitoring of free ammonia are recommended to ensure a proper disinfection. Our study confirms that monochloramine may be proposed as an effective and safe strategy for the continuous disinfection of building plumbing systems, preventing vulnerable individuals from being exposed to legionellae and dangerous DBPs.
Highlights
The control of Legionella contamination in complex water systems is still a critical issue, especially in healthcare settings where Legionella colonization of hot water systems is the primary risk factor for Legionnaires’ disease [1]
The aim of our study was to evaluate the possible formation of N-nitrosamines and other disinfection-by products (DBPs) in hospital hot water networks treated with monochloramine
N-nitrosamines analysis, hot water treated with chlorine dioxide were analyzed for comparison
Summary
The control of Legionella contamination in complex water systems is still a critical issue, especially in healthcare settings where Legionella colonization of hot water systems is the primary risk factor for Legionnaires’ disease [1]. National and international guidelines, aimed at preventing Legionella infections, recommend using biocides for contaminated hot water treatment [2,3]. Several physical and chemical disinfection methods have been proposed, but the most effective procedure has yet to be defined [4]. Chlorine-based disinfectants are cheap and widely used but they produce disinfection-by products (DBPs), which can pose potential health risks [5]. Res. Public Health 2020, 17, 6116; doi:10.3390/ijerph17176116 www.mdpi.com/journal/ijerph
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