Pesticides nitrosamine impurities

The discovery of nitrosamines in pesticide formulations, Ross et al (1976), led to remarkable public and regulatory reaction. The widely used herbicide, trifluralin, because of the inadvertent nitrosamine impurity, received the most attention. All dinitroaniline herbicides have similarities therefore, trifluralin, with appropriate exceptions, will serve as a suitable exan le. 

The presence of volatile nitrosamine impurities in pesticide formulations was an unsuspected phenomenon until the advent of more sensitive and reliable analytical tools for their detection, such as the Thermo Energy Analyzer. 

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... 

Nitrosamines in pesticides can occur as impurities or as inadvertant contaminants. They are formed in several ways ... 

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. 

And yet, this left the six classes of pesticides which contained detectable levels of N-nitrosamines and had to be regulated. The moratorium on these pesticides still remains in force until a policy has been established. The Agency also could not ignore that some regulatory action might have to be taJten on those pesticides that are already registered and contain detectable levels of nitroso impurities. 

Declaration of toxicological, ecotoxicological, or environmental significant impurities is needed. Especially hazardous chemicals like, for example, nitrosamines have to be declared and are regulated by a maximum admissible concentration. In this example, the total nitrosamine content of a pesticide formulation must not exceed 1 mg kg of the active substance present. 

Botanical extracts such as lanolin. Aloe vera, Centella asiatica or glycyrrhetic acid are studied. Vitamins such as A, C, B5 and E have also been reported. Studies on the following compounds used as ingredients can also be found heterocyclic compounds, organic acids, thiocompounds, alkanolamines, amines, amino acids, alcohols, peroxides, amides, polymers, peptides and ceramides. Analytical methods to determine toxic compounds present as impurities or as by-products such as nitrosamines, phenols, pesticides, polychlorinated biphenyls, etc. have also been proposed in literature. 

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