• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.3
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• pp.260-265
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• 1991

The effective method to detect the mutagenicity of N-nitrosodimethylamineI (NDMA) by using Salmonella/microsome assay was studied. The Effect of vitamin C on the mutagenicity of the formed NDMA and during the formation of NDMA from nitrite and secondary amine was also investigated. Aroclor 1254-induced hamster S9 mix was more effective in activation NDMA than rat S9 mix induced by Aroclor 1254 or phenobarbital. Dimethyl sulfoxide and ethanol suppressed the mutagenic effect of NDMA, however, phosphate butter (pH 7.4), distilled water, 95% methanol and Tween 80 + water (1 : 4) were the appropriate dissolving system in the mutagenicity test of NDMA. Vitamin C did not show any inhibitory effect on the mutagenicity of the formed NDMA. However, the revertants of Salmonella typhinutrium TA 100 were significntly reduced (p<0.05) when vitamin C was added to the reaction mixture of nitrite and dimethylamine during the formation of NDMA. The amount of the formed NDMA was analyzed using HPLC and the level was decreased by about 95%. Thus it was concluded that vitamin C inhibited greatly the formation of NDMA from nitrite and dimethylamine.

• Journal of Korean Society on Water Environment
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• v.30 no.1
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• pp.95-101
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• 2014

Overall studies for the N-nitrosodimethylamine (NDMA) formation and treatment methods were conducted. In this study, occurrence in several countries and emerging treatment technologies of NDMA were generally reviewed. The NDMA formation was dependent on pH, contact time, and molar ratio (monochloramine/dimethylamine). The formation was rapidly increased when the molar ratio was greater than 1. It was likely that monochloramine could be related to stimulate NDMA formation. NDMA concentrations in water supply and wastewater plants after disinfection were approximately 10 ng/L and 100 ng/L, respectively. UV oxidation and adsorption processes are regarded as effective technologies for the NDMA removal. It is suggested that the UV oxidation with proper lamps is applied in water supply system.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.402-406
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• 2006

N-Nitrosodimethylamine(NDMA) formation was studied as a function of chloramine concentration at a fixed dimethylamine (DMA) concentration of 0.05 mM at pH 7 and 8. Regression equations were developed by molar ratio of chloramine to DMA. The NDMA formation was dependent on molar ratio(chloramine/DMA) and was different when the ratio is less or greater than 1. The formation of NDMA increased with increasing chloramine concentration and a linear correlation was examined between NDMA concentration and the ratio on a log scale. The developed regression was applied to previously reported data and relative errors ranged from -79 to 163%. Regression equations could provide a potential tool to predict NDMA formation for a simple and quick estimation in water supply systems.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.390-393
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• 2005

N-nitrosodimethylamine (NDMA), a potent carcinogenic, has recently been observed at drinking water supply systems in USA and Canada. The NDMA formation was studied as a function of chloramine concentration (0.001-0.1 mM) at a fixed dimethylamine (DMA) concentration of 0.05 mM at different initial pH (6, 7, 8). It was found that the NDMA formation rate varied with pH values. The formation of NDMA increased with increasing chloramine concentration and showed maximum yields of 2.4% and 1.6% at pH 7 and 8, respectively. A good correlation ($r^2>0.99$) was observed between the molar ratio (chloramine/DMA) and NDMA formation at pH 7 and 8. Linearity of the NDMA formation appeared to be related to chloramine concentrations.

• Journal of the Korean GEO-environmental Society
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• v.12 no.2
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• pp.55-61
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• 2011

NDMA(N-Nitrosodimethylamine) has been considered as a carcinogenic pollutant even at extremely low-concentration (10ng/L). However, previous researches on NDMA have focused on mainly high concentration due to a difficulty of analysis. In this study, removal efficiencies were evaluated for individual or combined methods with PAC(Powder Activated Carbon), GS(Granular Sludge), MF(Microfiltration), UF(Ultrafiltration) and Silica gel(MCM-41, Diatomite, Spherical silica gel) at both aerobic and anaerobic conditions. Combined method of GS, PAC and UF membrane at anaerobic condition showed the highest removal efficiency of 65% while Silica gel showed the lowest removal efficiency of 6%. The outcomes of this study could be used further study of extremely low-concentration NDMA removal.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05a
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• pp.113-113
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• 2002

Effects of betaine intake on hepatic fibrogenesis were examined in adult male SD rats treated with nitrosodimethylamine (DMN; 10 ${\mu}\ell$/kg/day, ip) 3 days a week for 4 weeks. From two weeks prior to initiation of DMN treatment until sacrifice rats were provided with drinking water containing 1 % betaine.(omitted)

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.05a
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• pp.113-113
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• 2002

• 월간산업보건
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• s.215
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• pp.14-17
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• 2006

• 월간산업보건
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• s.214
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• pp.15-17
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• 2006

• Journal of Korean Society of Environmental Engineers
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• v.29 no.2
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• pp.192-196
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• 2007

In this study, a formation of N-nitrosodimethylamine(NDMA), a disinfection by-product, was investigated as a result of monochloramine addition in water. The NDMA formation was studied in terms of pH, dimethylamine(DMA), monochloramine concentration, and nitrogen composition in monochloramine. At a fixed DMA concentration of 0.01 mM or 0.05 mM, the NDMA formed concentration was quite different when the monochloramine to DMA ratio is less or greater than 1. The NDMA formation increased with increasing pH and a ratio of nitrogen composition in monochloramine to total nitrogen composition. At pH 7 and 8, more than five times higher NDMA formation was produced as a result of five times increase in DMA concentration. It was likely that monochloramine could be related to stimulate NDMA formation, if monochloramine may be produced with chlorine disinfection, in water treatment systems.