N-nitroso compounds and human intracranial tumours.

Experimentalists have shown that various N-nitroso compounds are potent nervous system carcinogens, particularly when animals are exposed transplacentally. Information has been obtained concerning exposure to N-nitroso compounds and their precursors in three case-control studies of intracranial tumour patients in Los Angeles County, California. A study of women (185 pairs) found that level of consumption of nitrite-cured meats was related to meningioma development (p = 0.01). In a similar study of meningiomas in men (105 pairs), the association with cured meats was not clear. The most striking results were obtained in a study of young brain tumour patients (209 matched pairs). Increased risk was associated with maternal contact, during pregnancy, with N-nitrosamine-containing substances, such as burning incense (odds ratio, 3.3; p less than 0.01), sidestream cigarette smoke (odds ratio, 1.5; p = 0.03) and face make-up (odds ratio, 1.6; p = 0.02). Increased risk was also associated with maternal use of diuretics (odds ratio, 2.0; p = 0.03) and antihistamines (odds ratio, 3.4; p less than 0.01) and with the level of maternal consumption of cured meats (p less than 0.01). Diuretics and antihistamines contain nitrosatable amines and amides, and cured meats contain nitrites - chemicals which are precursors of N-nitroso compounds. Additional epidemiological studies of nervous system tumours in young people would appear to offer considerable promise for testing the hypothesis that N-nitroso compounds are etiologically related to human neurogenic neoplasms.