The potential hazards of nitrosamines as toxicants formed in, or as a result of eating, certain foodstuffs have been described in newspapers (1), in testimony before congressional committees (2), in technical articles (3), and in consumer publications (4). We believe it appropriate therefore to review the status of knowledge of these substances to gain perspective and to distinguish between actual and potential occurrence of these compounds or their formation in vivo (or both). Some authors have carried out test tube reactions between nitrite and secondary amines and have indicated that these precursor substances are components of a number of foods we eat or drugs we take (5). However, it does not necessarily follow that by either in vitro or in vivo mechanisms we are being exposed to nitrosamines from a variety of sources. Evidence for the presence or formation of nitrosamines in foods is limited and some of the earlier reports of nitrosamines in human nutrients may have been based on inadequate analytical procedures (6). Furthermore, because pharnmacological data on the action of various nitrosamines are incomplete at

https://science.sciencemag.org/content/sci/177/4043/15.full.pdf

Nitrates, Nitrites, and Nitrosamines

Publisher Summary This chapter discusses the problem of nitrate accumulation in plants and the consequences of feeding nitrate or nitrite to animals. Most of the chemically combined nitrogen absorbed by plants is in the form of nitrate. The presence of nitrate within the tissues of certain species of plants is normal. In some crops, the nitrate content has been shown to be positively associated with ultimate yield and tissue testing of these crops has been advocated as a guide to optimum fertilization. The internal factors governing the accumulation of nitrate by plants include age, localization, and trait variations. Both stages of development and a number of environmental factors are known to influence nitrate content. The external factors governing the accumulation of nitrate by plants include nutrient supply, moisture content, intensity of light, and herbicides. In case of animals, both nitrate and nitrite, being highly water soluble, freely traverse the gastrointestinal wall into the bloodstream. Nitrite, but not nitrate, oxidizes the ferrous iron of the red blood pigment called hemoglobin to ferric iron, producing a modified brown-colored pigment called methemoglobin, which is incapable of transporting or releasing oxygen to the body tissues; animals so affected are said to be suffering from methemoglobinemia.

Nitrate Accumulation In Crops And Nitrate Poisoning In Animals

https://science.sciencemag.org/content/sci/168/3931/544.full.pdf

Ecological Effects of the War in Vietnam

The mode of action of foliage-applied translocated herbicides with particular reference to the phenoxy-acid compounds. 2. The mechanism and factors influencing translocation, metabolism and biochemical inhibition.

Nitrite poisoning in sheep, with special reference to the detoxification of nitrite in the rumen. An experimental study.

http://science.sciencemag.org/content/sci/112/2921/749.full.pdf

E. I. Whitehead

Papers

The effect of 2,4-D on potassium nitrate levels in leaves of sugar beets.