Carcinogenic compounds 3-Carotene

Lisle, E.B., The effect of carcinogenic and other related compounds on the autoxidation of carotene and other autoxidizable systems. Cancer Res., 11, 153, 1951. 

Nitrates and nitrites can give rise to other effects. They are, for example, able to decompose carotene. Nitrates affect the activity of the thyroid gland, which plays an important role in the conversion of carotene to vitamin A. The interactions of nitrites with amines are, however, much more dangerous, since they result in the production of jV-nitroso compounds. Many of these compounds damage the liver and exhibit teratogenic and carcinogenic effects [5, 15]. 

The presence of naturally occurring polynuclear aromatic (PAH) compounds is an interesting feature of soil organic matter. These compounds, some of which are carcinogenic, are discussed as air pollutants in Sections 10.8 and 12.4. PAH compounds found in soil include fluoranthene, pyrene, and chrysene. PAH compounds in soil result in part from combustion from both natural sources (grass fires) or pollutant sources. Terpenes also occur in soil organic matter. Extraction of soil with ether and alcohol yields the pigments P-carotene, chlorophyll, and xanthophyll. 

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