• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.2
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• pp.125-135
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• 1988

In recent years, the presence of N-nitrosamine, which was produced by the interaction of nitrite and secondary amine, in the fermented foods has been the subject of considerable interest and controversy. In this experiment, the levels of N-nitrosamine such as N-nitrosodimethylamine(NDMA), N-nitrosodiethylamine(NDEA) and N-nitrosodipropylamine(NDPA) in the Korean ordinary soysauce, which were added with ascorbic acid, sorbic acid, and sodium benzoate in the making of it were analyzed by low resolution mass spectrometry, and then the changes of dimethylamine(DMA), nitrate and nitrite nitrogen during the fermentation of it were observed. The contents of DMA nitrogen increased during the fermentation of Korean ordinary soysauce, continuously, but those of DMA nitrogen in the soysauce which had been added with ascorbic acid were inhibited, considerably, until the fermentation of 70days. The levels of nitrate nitrogen during the fermentation of Korean ordinary soysauee decreased, while those of nitrite nitrogen increased. The soysauce which had been incoporated with ascorbic acid in the making of it showed low amounts of nitrite. The concentration of NDMA in the control sample were 2.7 and $8.5{\mu}g/kg$ after the fermentation of 30 and 60 days, respectively, those of NDMA increased during the fermentation of Korean ordinary soysauce, but NDEA and NDPA in all of the soysauce were not detected. The samples were treated with ascorbic acid, sorbic acid, and sodium benzoate in the making of Korean ordinary soysauce were turn out to be effective in preventing the formation of NDMA. Inhibitive actions from food additives as above were, respectively, $82.2{\sim}87.0%$(ascorbic acid), $25.9{\sim}65.4%$(sorbic acid) an $13.2{\sim}63.5%$ (sodium benzoate) in comparison with control sample during the fermentation of Korean ordinary soysauce. NDMA contents were detected below $1.5{\mu}g/kg$ in the soysauce, which food additives were mixed to the pure NaCI in the brewing of it. Free amino acids such as glutamic acid, proline, and histidine were proved to be inhibiting the formation of NDMA during the fermentation of Korean ordinary soysauce. This might be due to the reaction above amino acids and nitrite by Van Slyke reaction.

• Korean Journal of Veterinary Pathology
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• v.5 no.1
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• pp.23-28
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• 2001

This study was conducted to assess the chemopreventive effects of sodium selenite in the rat medium-term multi-organ bioassay using a DMBDD model (DEN+MNU+BBN+DMH+DHPN). Seventy five,6-week-old, male SD rats were divided into 3 groups. The animals in group 1 received DEN(diethylnitrosamine,100 mg/kg bw, single i.p., in saline), MNU (N-methyl-nitrosourea,20 mg/kg bw, i.p.,4 times for 2 weeks), BBN (N-butyl-N-(4-hydroxybutyl) nitrosamine, 0.2% in drinking water for 2 weeks), DMH (1,2-dimethylhydrazine, 40 mg/kg bw, s.c., in saline.4 times (or 2 weeds), and DHPN (N-bis(2-hydroxy-pro-pal)nitrosamine,0.1% in drinking water for 2 weeks), then were placed on sodium selenite (4 ppm in drinking water) for 22 weeks from weeks 4 to 26. The animals in group 2 were given DMBDD alone. The animals in group 3 were given sodium selenite alone. Animals were sacrificed at week 12 for ACF quantitative analysis and at week 26 for tumor induction. The body weights in the group 1 were significantly decreased compared with those of group 2. The tumor multiplicities of large intestine in the group 1 were significantly decreased compared with those of group 2 (P<0.05). These results indicate that sodium selenite may have a potential as chemopreventive agents of colon carcinogenesis.

• Analytical Science and Technology
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• v.23 no.6
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• pp.551-559
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• 2010

This study was conducted to establish an analytical method for the determination of seven nitrosamines in chlorinated tap water by precolumn derivatization followed by high performance liquid chromatography coupled with fluorescence detection. The derivatization procedure was optimized for denitrosation and dansylation, and then two extraction methods, liquid-liquid extraction (LLE) with dichloromethane and solid phase extraction (SPE), were compared. The SPE method employing the optimized derivation procedure showed higher extraction recovery (54.4-88.7%) and reproducibility (1.9-19.4%) than the LLE method (51.4-87.7% and 4.2-33.3%, respectively). The method detection limits were between 0.5 and 4.4 ng/L. When chlorinated water samples were collected from two treatment plants and ten household taps, and analyzed for nitrosamines, Nnitrosodimethylamine (NDMA) was the major compound found between 26.1 and 112 ng/L.

• Environmental Analysis Health and Toxicology
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• v.26
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• pp.2.1-2.7
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• 2011

Objectives: N-Nitrosodimethylamine (NDMA) is classified as a probable human carcinogen by the United States Environmental Protection Agency (US EPA) and is formed during the chlorination of municipal drinking water. In this study, selected nitrosamines were measured in chlorinated drinking water collected from Chuncheon, Kangwon-do, Republic of Korea, and a risk assessment for NDMA was conducted. Methods: Twelve water samples were collected from 2 treatment plants and 10 household taps. Samples were analyzed for 6 nitrosamines via solid-phase extraction cleanup followed by conversion to dansyl derivatives and high-performance liquid chromatography-fluorescence detection (HPLC-FLD). Considering the dietary patterns of Korean people and the concentration change of NDMA by boiling, a carcinogenic risk assessment from ingestion exposure was conducted following the US EPA guidelines. Results: NDMA concentrations ranged between 26.1 and 112.0 ng/L. NDMA in water was found to be thermally stable, and thus its concentration at the end of boiling was greater than before thermal treatment owing to the decrease in water volume. The estimated excess lifetime carcinogenic risk exceeded the regulatory baseline risk of $10^{-5}$. Conclusions: This result suggests that more extensive studies need to be conducted on nitrosamine concentration distributions over the country and the source of relatively high nitrosamine concentrations.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.8
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• pp.1207-1216
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• 2014

Vegetables contain high levels of nitrate, which can be converted to nitrite for reaction with secondary amines to form nitrosamines. In this study, we evaluated safety effects against nitrite and nitrosamine as well as anti-mutagenic activities of vegetable juices. To do this, the contents of nitrate, nitrite, and nitrosamines were determined in vegetable juices. The safety effects against nitrite and nitrosamine formation were also investigated under simulated human gastric conditions. The contents of nitrate and nitrite in common and organic kale and Angelica keiskei juices were 931~2,052 mg/kg and 13~82 mg/kg, respectively. However, seven kinds of nitrosamines were not detected in the vegetables juices. The nitrate content decreased when vegetable juices were digested under simulated human gastric conditions. Nitrosamine (N-nitrosodimethylamine) formation under simulated human gastric conditions was inhibited by addition of vegetable juices. In addition, vegetable juices, especially organically cultivated juices, showed anti-mutagenic effects in a Salmonella assay system. These results suggest that organically cultivated vegetable juices are a promising health-promoting source.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.104-105
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• 2002

N-nitrosamine(NA)은 여러 가지 발암성 물질 중에서도 발암력이 매우 강하면서, 각종식품에 널리 분포되어 있고, 위, 간, 식도 및 신장 등 신체의 여러 부분에서 발암력을 나타낸다는 점과 nitroso 화합물 중 어떤 물질들은 후손에게까지 악성종양의 유발에 영향을 미친다는 점들을 들 수 있다. nitroso 화합물의 생성은 식품중에 존재하는 아질산염과 제2급아민이나 혹은 제 3급아민과의 상호반응으로 생성되기 때문에 식품에 있어서 이들의 존재가 상당한 논쟁의 대상이 되고 있다. (중략)

• Korean Journal of Food Science and Technology
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• v.42 no.5
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• pp.541-548
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• 2010

In this study, contamination levels of 7 N-nitrosamine were investigated in processed meat products (n=51), processed fish products (n=62), salted fish pickles (n=20), and beer and malt beverages (n=21) using a GC/PCI-MS/MS method. The limits of detection (LOD) of the N-nitrosamines ranged from 0.2 to 0.5 ${\mu}g$/kg. In addition, methods were used to estimate the recovery of 7 N-nitrosamines, which ranged from 84 to 112%. N-nitrosamines were detected in 89 (58%) out of 154 samples. The exposure of an entire population group to N-nitrosamines through food intake was estimated using the average body weight of the total population and average daily food consumption, to perform risk assessment based on reports of a national health and nutrition survey. The results indicated that the daily intake of N-nitrosamines over a life time was $4.92{\times}10^{-7}$ mg/kg b.w./day. The margin of exposure (MOE) for the general population, estimated using the benchmark dose lower confidence limit 10 ($BMDL_{10}$) of N-nitrosodimethylamine, was 208,939, which was found to be safe.

• YAKHAK HOEJI
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• v.30 no.1
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• pp.8-13
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• 1986

It has been assumed that nitrite, one of the precursor of N-nitrosamine, in human saliva must have been formed from salivary nitrate through the action of microorganism in the oral cavity. In this paper, we have tested the concentration of nitrite and nitrate in human saliva and the degrees of nitrate reduction by oral microflora and identified some bacteria which were able to reduce nitrate. The concentration of nitrite and nitrate was 1.7~9.5ppm and 9.0~28.5ppm respectively. The numbers of total bacteria and nitrate reducing bacteria in four korean human saliva sample were 15~63${\times}10^8$ CFU and 1.0~6.0${\times}10^8$ CFU and the main nitrate reducing bacteria were Streptococcus uberis which was presented in large quantities and showed remarkable reductive activity. Lastly, we knowed that N-dimethylnitrosamine was formed by the reaction between dimethylamine and nitrite in the presence of St. uberis in vitro.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.11
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• pp.764-770
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• 2014

This study assessed analysis of N-nitrosamines by separation, identification, and quantification using a gas chromatography (GC) mass spectrometer (MS) with electron impact (EI) mode. Samples were pretreated by a automated solid phase extraction (SPE) and a nitrogen concentration technique to detect low concentration ranges. The analysis results by EI-GC/MS (SIM) and EI-GC/MS/MS (MRM) on standard samples with no pretreatment exhibited similar results. On the other hand, the analysis of pretreated samples at low concentrations (i.e. ng/L levels) were not reliable with a EI-GC/MS due to the interferences from impurity peaks. The method detection limits of eight (8) N-nitrosamines by EI-GC/MS/MS analysis ranged from 0.76 to 2.09 ng/L, and the limits of quantification ranged from 2.41 to 6.65 ng/L. The precision and accuracy of the method were evaluated using spiked samples at concentrations of 10, 20 and 100 ng/L. The precision were 1.2~13.6%, and the accuracy were 80.4~121.8%. The $R^2$ of the calibration curves were greater than 0.999. The recovery rates for various environmental samples were evaluated with a surrogate material (NDPA-$d_{14}$) and ranged 86.2~122.3%. Thus, this method can be used to determine low (ng/L) levels of N-nitrosamines in water samples.

• Journal of Oral Medicine and Pain
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• v.15 no.1
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• pp.125-132
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• 1991

We have previously reported that simulated snuff dipping in conjunction with type I herpes simplex virus (HSV-1) induced oral malignant changes in hamsters. Present study was designed to investigate the carcinogenic effect of tobacco specific-N-nitrosamines (TSNAs) and HSV-1, alone or in combination, in hamsters. Hamsters were divided into 6 groups and the right buccal pouch mucosa were treated as follows: Grp 1, Control (Mock inoculation) [MI]+Topical Application [TA] of mineral oil[MO] : Grp 2, TA of 1% n'- nitrosonornicotine [NNN] + IM: Grp3, TA of 1% 4-N-nitrosomethylamino-1- (3-pyridyl)-1-butanone [NNK] + MI: Grp 4, HSV-1 inoculation [HI]+TA of MO : Grp 5, TA of 1% N-nitrosonornicotine [NNN] + HI: Grp 6, TA of 1% NNK + HI. TA of MO or TSNAs was initiated 1 day after the MI or HI and given 3 times per week for 20 consecutive weeks. At the buccal pouches were fixed for light microscope examination. No animal s developed tumors or malignant histopathologic changes in the mucosa of the buccal pouches. These data indicate that individual TSNAs, alone or in conjunction with HSV-1 infection, do not develop malignant changes in hamster buccal pouches.