Nitrosamines: Economics of the Unknown (original) (raw)
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2013
N-nitrosamines are considered as a group of emerging disinfection byproducts (DBPs) with potential carcinogenicity at ng/L level. The presence of nitrosamines in drinking water is most commonly associated with chloramination of amine-based precursors. This research investigates the potential of amine-based pharmaceuticals and personal care products (PPCPs) as nitrosamine precursors under practical drinking water disinfection conditions, as well as some critical factors that may affect the nitrosamine formation via PPCPs. All of the twenty selected PPCPs were able to form the corresponding nitrosamines upon chloramine disinfection, and eight of them rendered molar conversions higher than 1 % under practical disinfection conditions. Ranitidine had the highest N-nitrosodimethylamine (NDMA) molar conversion among the tested PPCPs. A three-parameter kinetic model was proposed to describe and predict the NDMA formation from pharmaceuticals during chloramination in various water matrices. ...
Journal of hazardous materials, 2014
The worldwide detection of pharmaceuticals and personal care products (PPCPs) in aquatic environment and drinking water has caused wide concern in recent years. The possibility for concurrent formation of N-nitrosodimethylamine (NDMA) during disinfection has become another significant concern for water quality. This study demonstrates that a group of PPCPs containing amine groups can serve as NDMA precursors during free chlorine or chlorine dioxide (ClO2) chlorination processes. Selected PPCPs after screening by NDMA yield were further investigated for NDMA formation conditions. High disinfectant dose and initial PPCP concentration resulted in relatively high NDMA formation potential. Linear kinetic models were developed for NDMA formation during chlorination of selected PPCPs. Although the PPCP precursors were removed significantly during chlorination, they were not completely mineralized based on the total organic carbon (TOC) loss. The existence of another possible pathway for di...
Effectiveness of switching disinfectants for nitrification control
Journal American Water Works Association, 2008
The effectiveness of a one-month switch from chloramines to free chlorine for control of nitrification and the consequences of this strategy were evaluated in three distribution systems. Nitrification was observed in two of the systems, and may have been influenced by greater loss of disinfectant residual in cast-iron pipe sections. Free chlorine inhibited nitrification episodes, though evidence of nitrification was observed several months after the return to chloramines. Ammonia-oxidizing bacteria (AOB) were found attached to pipe-wall specimens removed from a distribution system during and at the end of the free-chlorination period, suggesting AOB persisted during free chlorination. Consequences of disinfectant switching include breakpoint chlorination reactions that caused periods of low disinfectant residuals and increased total trihalomethane (TTHM) concentrations. The highest TTHM concentration might not be observed until long after the return to chloramines at locations with long residence time where free chlorine remains.
International Journal of Environmental Science and Technology, 2019
Chloramination and chlorination contribute to the formation of N-nitrosodimethylamine and trihalomethanes, respectively, both of which are defined as disinfection by-products. To be able to select the most appropriate water treatment scheme, it is important to comparatively evaluate the formation of both of these disinfection by-products during the application of different disinfection methods. In this study, chlorination, chloramination and stepwise chloramination methods have been applied to surface water samples that have been spiked with known N-nitrosodimethylamine precursors. Experimental results showed that ranitidine can be an effective N-nitrosodimethylamine precursor in distilled water, when chloraminated with high concentrations (140 mg/L) for a long time (10 days), resulting in approximately 450 ng/L of N-nitrosodimethylamine. However, neither dimethylamine nor ranitidine leads to significant trihalomethanes or N-nitrosodimethylamine formation in lake water when chloramination is conducted with low concentration (2 mg/L) for 2 h. These results suggest that N-nitrosodimethylamine concentration measured in the effluent of the drinking water treatment plant may underestimate the N-nitrosodimethylamine concentration that will reach the consumers since chloramination reactions will continue in the distribution system. On the other hand, when only N-nitrosodimethylamine formation potential is used, it will overestimate the N-nitrosodimethylamine that might form in the distribution system due to high disinfectant concentration, high contact time and adjusted pH values used in the N-nitrosodimethylamine formation potential test.
Chemosphere, 2014
We determined whether or not the chloramination or ozonation of amines and hydrazines listed in Pollutant Release and Transfer Registers (PRTRs) results in the formation of Nnitrosamines when reacted in secondary wastewater effluent. We selected 12 primary, 2 secondary, 2 tertiary amines and 3 hydrazines from the PRTRs of Japan, the USA, and Korea. In this study, based on the assumption that there is a production of N-nitrosamines by not only the original selected amines and hydrazines but also the intermediate products in case of chloramination and ozonation, it was examined whether precursors were identified by selected amines and hydrazines based on the gap of the N-nitrosamines formation potential between day 0 and day 10 rather than analyzing the contribution depending on the concentration of selected amines and hydrazines. Many of the primary amines (notably 2,6xylidine) and all of the secondary and tertiary amines produced N-nitrosodimethylamine (NDMA) by chloramination. Furthermore, the primary amines 2,6-xylidine, 3,3′dimethylbenzidine, 4,4'-methylenebis(2-chloroaniline), 4-aminoazobenzene, p-chloroaniline, and p-cresidine produced more NDMA than did the secondary amines. The secondary amines produced mainly NDMA. Ozonation produced NDMA only from the hydrazine 1,1dimethylhydrazine, and at a higher concentration than by chloramination. We identified 2,6xylidine, 3,3′-dimethylbenzidine, 4,4'-methylenebis(2-chloroaniline), 4-aminoazobenzene, pchloroaniline, p-cresidine, 1,1-dimethylhydrazine, diethylamine, 4,4′-methylenebis(N,Ndimethyl)benzenamine, and chinomethionat as warranting further study.
Analytical and Toxicological Characterization of Novel Nitrogen Containing Disinfection Byproducts
2012
Disinfection byproducts (DBPs) are an unwanted consequence of water disinfection. Consumption of chlorinated drinking water has been associated with an increased risk of bladder cancer; however, the DBP or DBPs responsible has not been identified. The N-nitrosamines are a class of DBPs that are known rodent carcinogens. They are more potent than the currently regulated DBPs and may be capable of causing health effects at low ng/L concentrations. Due to these possible health concerns, the study of nitrosamines in drinking water is warranted. Gas chromatography mass spectrometry (GC-MS) is the main technique used for nitrosamine analysis, but cannot directly detect thermally unstable or non-volatile nitrosamines. A liquid chromatography tandem MS (LC-MS/MS) method was developed that is capable of detecting GC-detectable nitrosamines, such as N-nitrosodimethylamine (NDMA), and GC-non-detectable nitrosamines. Using this method, N-nitrosodiphenylamine (NDPhA), a thermally unstable nitrosamine, was detected as a DBP from an authentic drinking water sample. A survey of 38 North American drinking water systems using the LC-MS/MS method found that NDMA was the most commonly detected nitrosamine (28 of 38 systems) followed by NDPhA (6 of 38 systems). A real-time cell electronic sensing (RT-CES) technique was developed and demonstrated as a useful tool for DBP toxicity testing. NDPhA was more cytotoxic than NDMA in four cell lines. Further mechanistic analysis determined that NDPhA induces cell cycle arrest, which is different than other nitrosamines such as NDMA. Studies on nitrosamine formation showed the important role of source water. Disinfectant type alone was not sufficient to determine which nitrosamines are formed. Additional studies determined that diphenylamine (DPhA) can form NDPhA, particularly in the presence of monochloramine. This reaction also formed phenazine and N-chlorophenazine. Further investigation determined that phenazine containing natural products produced by bacteria are also precursors for the phenazine containing DBPs. These results suggest that the currently monitored nitrosamines are not widespread enough to be solely responsible for the observed increase in bladder cancer risk. However, there are several locations where elevated nitrosamine concentrations are a concern. Until the DBP cancer culprit is identified, reduction of overall DBP formation through source water management and careful monitoring of the disinfection process is the best practice to manage cancer risks posed by DBPs. I have been so lucky to work with such a large group of people as part of the AET Division.
2010
Formation of nitrogenous disinfection by-products (N-DBPs) of cyanogen chloride (CNCl), dichloroacetonitrile (DCAN) and chloropicrin was evaluated during chloramination of several selected groups of nitrogenous organic (organic-N) compounds, including a-amino acids, amines, dipeptides, purines, and pyrimidines, The intermediates generated, reaction pathways, and nitrogen origin in N-DBPs were explored as well. CNCl was observed in chloramination of all tested organic-N compounds, with glycine giving the highest yields. DCAN was formed during chloramination of glutamic acid, cytosine, cysteine, and tryptophan. Chloramination of most organic-N compounds except for cysteine and glutamic acid generated chloropicrin. Aldehydes and nitriles were identified as the intermediates by negative mode electrospray ionization mass spectrometry during reactions of NH 2 Cl and organic-N compounds. Labeled 15 N-monochloramine (15 NH 2 Cl) techniques showed that nitrogen in N-DBPs may originate from both NH 2 Cl and organic-N compounds and the nitrogen partition percentages vary as functions of reactants and pH.
Occurrence and removal of N-nitrosamines in wastewater treatment plants
Water Research, 2009
Nitrosamines Wastewater Sewage treatment plant Degradation a b s t r a c t The presence of nitrosamines in wastewater might pose a risk to water resources even in countries where chlorination or chloramination are hardly used for water disinfection. We studied the variation of concentrations and removal efficiencies of eight N-nitrosamines among 21 full-scale sewage treatment plants (STPs) in Switzerland and temporal variations at one of these plants. N-nitrosodimethylamine (NDMA) was the predominant compound in STP primary effluents with median concentrations in the range of 5-20 ng/L, but peak concentrations up to 1 mg/L. N-nitrosomorpholine (NMOR) was abundant in all plants at concentrations of 5-30 ng/L, other nitrosamines occurred at a lower number of plants at similar levels. From concentrations in urine samples and domestic wastewater we estimated that human excretion accounted for levels of <5 ng/L of NDMA and <1 ng/L of the other nitrosamines in municipal wastewater, additional domestic sources for <5 ng/L of NMOR. Levels above this domestic background are probably caused by industrial or commercial discharges, which results in highly variable concentrations in sewage.
Reduction of nitrosamines in cosmetic products
International journal of cosmetic science, 1995
Summary From initial rate studies of morpholine nitrosation in aqueous media by nitrite ion in the presence of formaldehyde at pH 5-7 and 25 degrees C, four potential pathways are revealed for the concurrent formation of nitrosamine contaminants in cosmetic and toiletry products. Three of the pathways involve conventional electrophilic nitrosation by XNO reagents of both neutral amine and N-hydroxymethylamine compounds obtained by prior reaction with formaldehyde. The fourth pathway involves a nucleophilic reaction by nitrite ion with the iminium ion derived from N-hydroxymethylamine. For morpholine, reaction via XNO reagents is substantial at pH 5 only, whereas the iminium ion pathway is pre-eminent at pH 7. The concurrent formation of nitrosamines by mechanistically different pathways implies that combinations of nitrosation inhibitors are necessary to minimize contamination of cosmetic and toiletry products. For these different pathways, novel inhibitory compounds are described w...