Nitrosamines influence

Evidence exists that the relative solubility of amines and inhibitors in heterogeneous oil-water systems could be decisive in formation of nitrosamines and blocking these reactions, Nitrosopyrrolidine formation in bacon predominates in the adipose tissue despite the fact that its precursor, proline, predominates in the lean tissue (5,6,7). Mottram and Patterson (8) partly attribute this phenomenon to the fact that the adipose tissue furnishes a medium in which nitrosation is favored, Massey, et al, (9) found that the presence of decane in a model heterogeneous system caused a 20-fold increase in rate of nitrosamine formation from lipophilic dihexylamine, but had no effect on nitrosation of hydrophilic pyrrolidine. Ascorbic acid in the presence of decane enhanced the synthesis of nitrosamines from lipophilic amines, but had no effect on nitrosation of pyrrolidine. The oil-soluble inhibitor ascorbyl palmitate had little influence on the formation of nitrosamines in the presence or absence of decane. 

Nitrite concentration The kinetics of N-nitrosamine formation in vitro has been studied at length (, ) and, in moderately acidic media, the reaction rate is directly proportional to the concentration of the free amine (non-protonated) and to the square of the concentration of the undissociated nitrous acid. Therefore, it is not surprising that the amount of nitrite permitted in bacon has received considerable attention. Although, there have been suggestions that it is the initial and not the residual nitrite that influences N-nitrosamine formation in bacon (41), recent evidence seems to indicate that the lowest residual nitrite gives the least probability of N-nitrosamines... 

In addition to vitamin C and vitamin E as effective blocking agents, there are other substances which also are capable of preventing nitrosamine formation which are present in normal foods. The influence of this factor on the design of experimental studies should not be overlooked. 

Possible exposure to pesticide-derived N,-nitroso compounds depends on environmental processes that influence formation, movement, and degradation of the compounds. Although laboratory studies have shown the feasibility of environmental nitrosamine formation, there has been little evidence that it is an important process. Nitrosamines vary greatly in their environmental stabilities, but all seem to be susceptible to one or more modes of decomposition including photolysis, microbiological degradation, and plant metabolism. 

Other environmental properties of interest are those that govern movement of chemicals, for these properties can influence not only the possibility of human exposure but also the lifetime and fate of the chemical. Clearly, if a nitrosamine is formed in, or introduced into, the soil and stays there, it presents little threat to man, and its lifetime will depend on the chemical or microbiological properties of the soil. If it should move to the surface and volatilize into the atmosphere, on the other hand, there will exist the possibility of human exposure via inhalation and also the possibility of vapor-phase photodecomposition. If a nitrosamine were to leach from soil into water, it could perhaps be consumed in drinking water alternatively, exposure of the aqueous solution to sunlight could provide another opportunity for photodecomposition. 

Four nitrosamines, seven nitramines, three nitroesters and the explosives Semtex 10 and Composition B have been investigated by TGA. Linear dependence was confirmed between the position of the TGA onsets, as defined in the sense of Perkin-Elmer s TGA-7 standard program, and the samples weights. The slope of this dependence is closely related to the thermal reactivity and molecular structure. The intercept values of the dependence correlate with the autoignition temperatures and with the critical temperatures of the studied compounds, without any clear influence from molecular structure. Results show that Semtex 10 exhibits approximately the same thermostability as its active component pentaerythrityl tetranitrate (PETN, 274). Results also show that TGA data for Composition B do not correlate with analogous data for pure nitramines564. 

Burton HR, Bush LP, Djordjevic MV (1989a) Influence of temperature and humidity on the accumulation of tobacco-specific nitrosamines in stored burley tobacco, J Agric Food Chem 37 1372-1377... 

Counts ME, Morton MJ, Lafoon SW, Cox RH, Lipowicz PJ (2005) Smoke composition and potential relationship for international commercial cigarettes smoked with three machine-smoking conditions, Regul Toxicol Pharmacol 41 185-227 DeRoton C, Wiemik A, Wahlberg 1, Vidal B (2005) Factors influencing the formation of tobacco-specific nitrosamines in french air-cured tobaccos in trials and at the farm level, Beitr Tabakforsch 21 305-320... 

Cooney. R. V., Ross, P.D., Bartolini, G.L., and Ramseyer, J. IV-Nitrosamine and IV-nitroamine formation factors influencing the aqueous reachons of nitrogen dioxide with morpholine. Environ. Sci. Technol, 21 (l) 77-83,1987. 

Zijlstra, J.A. Vogel, E.W (1988) Influence of inhibition of the metabolic activation on the mutagenicity of some nitrosamines, triazenes, hydrazines and seniciphylline in Drosophila melanogaster. Mutat. Res., 202, 251-267... 

Variations in the use pattern of industrial and agricultural chemicals throughout the world preclude standardization by international organizations such as OECD. Despite this fact, common dietary constituents, which are known to influence toxicity are antioxidants, unsaturated fatty acids, and selenium. These must be present in interfering concentrations. The potential impact of several common dietary contaminants on chronic toxicity assessment therefore, necessitates that special attention be given to their presence. In this respect, substances of concern include pesticide residues, chlorinated and polycyclic aromatic hydrocarbons, estrogens, heavy metals, nitrosamines, and mycotoxins. 

An interesting example of how the reaction conditions can influence the structure of the product is given in (24). Depending on the acidity of the reaction medium and on the reaction time, the diazotization of aminotriazoles 42 yields the nitrosamines 43, the chlorb compounds 44, or the azo coupling product, i.e. the diazoamino compounds 45... 

There is considerable evidence that the processes related to food processing on both industrial and household scales influence the formation of lutrosamines. For example, in fresh fish the content of Ai-nitrosamines is greater than 5 g/kg, whereas in processed fish (stored) it reaches 13 g/kg. The amount of these compounds is higher in smoked products. Studies of 300 types of processed pork showed that the average content of NDMA is 3 g/kg, but the highest concentration was as high as 50 g/kg. 

Lakritz L, Pensabene JW. 1984. Survey of human milk for volatile N-nitrosamines and the influence of diet on their formation. Fd Chem Toxicol 22 721-724. 

Brunnemann, K.D., J.D. Adams, D.P.S. Ho, and D. Hoffmann The influence of tobacco smoke on indoor atmospheres. II. Volatile and tobacco-specific nitrosamines in mainstream and sidestream smoke and their contribution to indoor poUntion Proc. 4th Joint Conf. on Sensing of Environmental PoUntants, New Orleans, LA, Am. Chem. Soc. (1977) 876-880. 

Caldwell, W.S., J.M. Greene, G.P. Dobson, and J.D. deBethizy Intragastric nitrosation of nicotine is not a significant contributor to nitrosamine exposure in Tobacco smoking and nutrition Influence of nutrition on tobacco-associated health risks, edited by J.N. Diana and W.A. Pryor, Ann. N.Y. Acad. Sci. 686 (1992) 213-228, see www.rjrtdocs.com 514892394 -2401. 

J. L. Verrier Study of factors influencing the concentration of tobacco-specific nitrosamines (TSNA) in air-cured tobaccos 55th Tobacco Science Research Conference, Program Booklet and Abstracts, Vol. 55, Paper No. 98, 2001, p. 77. 

Fischer, S., B. Spiegelhalder, and R. Preussmann Preformed tobacco-specific nitrosamines in tobacco Role of nitrate and influence of tobacco type Carcinogenesis 10(1989) 1511-1517. 

The reduction in nitrosamine formation may actually arise secondarily to increased formation of nitrosothiols. Williams suggested almost 20 years ago [78] that several sulfur compounds may reduce nitrite availability for nitrosamine formation by enhancing the formation of nitrosothiols. Since the allyl sulfur content among garlic preparations can vary enormously, it is reasonable that all commercial preparation will not be equivalent in their ability to retard nitrosamine formation. While S-nitrosylation is known to influence health and disease [29], it is unclear how garlic influences this process across various cell types. 

At the pH of beer ammonia and the other volatile amines in beer (Table 22.18) will be present as their non-volatile salts. Ammonia is the most abundant volatile nitrogenous constituent the mean value in a range of US beers was 14 6 ppm (3-33 ppm) compared with 21 3 ppm (0-33 ppm) in imported beers [93]. At the low concentrations found, the volatile amines will have little influence on the flavour of beer. Dimethylamine is commonly the major constituent. Secondary amines such as dimethylamine react with nitrogen oxides to form carcinogenic A -nitrosamines ... 

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