ABSTRACT
Photolytic. N-nitrosodimethylamine absorbs UV at 228 nm. An enhanced oxidation process equipped with UV lamps (195 to 240 nm), mineralized >99.9 % of N-nitrosodimethylamine in water to concentrations <0.25 µg/L (Smith, 1992). A Teflon bag containing air and N-nitrosodimethylamine was subjected to sunlight on two different days. On a cloudy day, half of the N-nitrosodimethylamine was photolyzed in 60 min. On a sunny day, half of the N-nitrosodimethylamine was photolyzed in 30 min. Photolysis products include nitric oxide, carbon monoxide, formaldehyde, and an unidentified compound (Hanst et al., 1977). Tuazon et al. (1984a) investigated the atmospheric reactions of N-nitrosodimethylamine and dimethylnitramine in an environmental chamber utilizing in situ long-path Fourier transform infared spectroscopy. They irradiated an ozone-rich atmosphere containing N-nitrosodimethylamine. Photolysis products identified include dimethylnitramine, nitromethane, formaldehyde, carbon monoxide, nitrogen dioxide, nitrogen pentoxide, and nitric acid. The rate constants for the reaction of N-nitrosodimethylamine with OH radicals and ozone relative to methyl ether were 3.0 x 10-12 and ≤1 x 10-20 cm3/molecule⋅sec, respectively. The estimated atmospheric half-life of N-nitrosodimethylamine in the troposphere is approximately 5 min. Chemical/Physical. N-Nitrosodimethylamine will not hydrolyze because it does not contain a hydrolyzable functional group (Kollig, 1993). Odziemkowski et al. (2000) studied the reduction mechanism of N-nitrosodimethylamine by granular iron using potentiostatic electrolysis and differential pulse voltammetry. In the electrochemical experiments, dimethylamine and nitrous oxide formed. The investigators reported that in an earlier experiment using batch and column experiments, nitrous oxide, characteristic of electrochemical reduction, was not detected. Rather, ammonia and dimethylamine were the products identified. The investigators proposed catalytic hydrogenation was the mechanism for N-nitrosodimethylamine reduction. In water, N-nitrosodimethylamine reacts with OH radicals via abstraction of the hydrogen atom on the methyl group. The rate constant for this reaction is 4.30 x 108/M⋅sec. No significant intermediate compounds were identified in the absorption range 250-800 nm (Mezyk et al., 2004). At influent concentrations of 10 and 1.0 mg/L, the GAC adsorption capacities were 250 and 6.8 x 10-5 mg/g, respectively (Dobbs and Cohen, 1980). Exposure limits: Potential occupational carcinogen. Given that no standards have been established, NIOSH (1997) recommends the most reliable and protective respirators be used, i.e., a self-contained breathing apparatus that has a full facepiece and is operated under positive-pressure or a supplied-air respirator that has a full facepiece and is operated under pressure-demand or under positive-pressure in combination with a self-contained breathing apparatus operated under pressure-demand or positive-pressure. OSHA recommends that worker exposure to this chemical is to be controlled by use of engineering control, proper work practices, and proper selection of personal protective equipment. Specific details of these requirements can be found in CFR 1910.1003-1910.1016. Toxicity: LC50 (inhalation) for mice 57 ppm/4-h, rats 78 ppm/4-h (quoted, RTECS, 1985). Acute oral LD50 for hamsters 28 mg/kg, rats 45 mg/kg (quoted, RTECS, 1985). Source: After 2 d, N-nitrodimethylamine was identified as a major metabolite of dimethylamine in an Arkport fine sandy loam (Varna, NY) and sandy soil (Lake George, NY) amended with sewage and nitrite-N. Mills and Alexander (1976) reported that N-nitrosodimethylamine also formed in soil, municipal sewage, and lake water supplemented with dimethylamine (ppm) and nitrite-N (100 ppm). They found that nitrosation occurred under nonenzymatic conditions at neutral pHs. Glória et al. (1997) reported N-nitrodimethylamine was detected in 50% of domestic beers at
imported beers purchased in the U.S., N-nitrodimethylamine was detected in 63% of 78 beers analyzed at concentrations up to 0.55 µg/kg. The average N-nitrodimethylamine concentration was 0.09 µg/kg. Uses: Rubber accelerator; solvent in fiber and plastic industry; rocket fuels; lubricants; condensers to increase dielectric constant; industrial solvent; antioxidant; nematocide; softener of copolymers; research chemical; plasticizer in acrylonitrile polymers; inhibit nitrification in soil; chemical intermediate for 1,1-dimethylhydrazine.
