Nitrosamine contamination

Wet chemical methods determining titratable amine ate reported for products entering urethane (amine number as meq/g) or epoxy (AHEW = amine hydrogen equivalent weight) trade appHcations. For secondary amines /V-nitrosamine contaminants are reportable down to ppb using Thermoelectron Corporation thermal energy analy2er techniques. 

These studies led to some important insights regarding the pathways by which nitrosamine contamination can occur in pesticides, many of which have been described in the literature since the problem was discovered. Let us look at selected papers which have provided this information so we can understand the mechanisms involved, and then at some of the strategies for contamination control which have grown out of these principles. 

The nitrosamine contamination of rubber products originates from amine-containing accelerators and... 

Several aspects of the problem of herbicides being contaminated with nitrosamines, and the resulting inadvertent introduction of nitrosamines into the environment, will be discussed in other papers in this symposium. Unrecognized until less than five years ago, the situation has inspired intense debate and prompted several of the environmental chemistry studies mentioned in this paper. Like the presumed threat from the in vivo nitros-ation of pesticide residues, discussions sometimes lack the type of anticipated dose and effect calculations just mentioned. Unlike the active ingredients, whose benefits can justify residue tolerances and acceptable daily intakes, nitrosamine contaminents afford no known benefits, and the desirability of minimizing their levels is undisputed. 

The discovery of nitrosamine contaminants In some pesticides has led to a major technological effort to prevent, reduce or eliminate formation of these Inadvertent Impurities In pestlcldp formulations. Although the nitrosamine... 

Chemically, nitrosamines are considered to be quite stable compounds and are difficult to destroy cmce they are formed. Reducing or destroying preformed nitrosamines in pesticides offers special challenge, as they occur in trace amounts which require specific selective treatment without effecting the composition of the principal product. Experimental laboratory work revealed that reactions suitable for mass quantities of reactants, that is neat samples, are not necessarily analagous to micro reactions for the reduction of a given trace nitrosamine contaminant or impurity. 

Effects of TSCA on the Metalworking Fluids Industry Increased Awareness of Nitrosamine Contamination... 

The various effects of the Toxic Substances Control Act (TSCA) on the metalworking fluids Industry is presented, with emphasis placed on nitrosamine contamination of the fluids. A review of the literature on the effects of various metalworking fluid additives on nitrosamine formation is also presented to aid the industry in dealing with the nuisance of nitrosamine contamination. It is concluded that with increased awareness of nitrosamine contamination as a result of the implementation of TSCA and careful consideration of the factors described in this paper, it may be possible to design and control a nitrosamine-free metalworking fluid. 

Section 8 of TSCA has made EPA and the industry aware of nitrosamine contamination in metalworking fluids. In one particular potentially significant notice of substantial risk (8E-1077-0 012), skin painting studies showed an increase above the expected normalincidence of tumors in the livers and lungs of mice with no unusual incidence of skin tumors. Due to the similarity between the observed effects and the mechanism of action of nitrosamines (i.e., the apparent systemic effect of the substance and organ specificity of the tumors), the company attributed the response to a nitrosamine contaminant in the fluid. 

The following discussion is intended to show how metalworking fluids can affect nitrosamine formation, even when their formation is not apparent. It is also intended to provide the industry with information that may enable it to cope with unforeseen nitrosamine contamination in metalworking fluids. 

A-nitrosodimethylamine (NDMA). A-Nitrosomorpholine (NMOR) is also produced in this process, but the origin of this pollutant is unknown. Samples collected from different tanneries showed airborne nitrosamine contamination ranging from 0.05-47 Xg/m3 NDMA (mean 3.4 pg/m3) and 0.05-2.0 pg/m3 NMOR (mean 0.2 pg/m3)64. Studies have indicated the possible risk of nasal cancer to workers exposed to NDMA at a daily exposure level of 440 pg NDMA/person/day and 20 pg NMOR/person/day65. Animals exposed to long-term inhalation of NDMA were found to have formed malignant tumours of mainly the liver and kidney66. 

There are several routes for nitrosamine contamination in pesticides use of contaminated chemicals during synthesis, side reactions, use of nitrite as a preservative and corrosion inhibitor of metal containers and by reactions with environmental nitrosating agents. Over 300 formulations were shown to be contaminated with nitrosamines however, the main contamination was confined to 2,6-dinitroaniline herbicides, dimethylamino salts of phenoxyalkanoic acid herbicide, diethanolamine and triethanolamine salts of acid... 

In the past seven years N-nitrosamines have attracted wide attention due to their carcinogenic properties. In 1977, Ross et al. (67) reported the presence of N-nitrosodipropylamine in the formulation of dinitroaniline herbicide, trifluralin, at the 154 ppm level. Subsequent studies by other laboratories showed that nitrosamine impurities are common to all dinitroaniline-based herbicides. Nitrosamines contamination resulted from the nitration of dipropylamine by the excess nitrosating agent. 

Determination of the total level of nitrosamine contamination of some consumer products in Nigeria Inti. J. 

Table 4 DINITROANILINE AND SIMILAR HERBICIDES SCREENED FOR NITROSAMINE CONTAMINATION (40)...

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