We questioned mothers of 209 young brain tumor patients and mothers of 209 
controls about experiences of possible etiological relevance which they had 
during pregnancy or which their children had while growing up. Long-suspected 
brain tumor risk factors such as head trauma and X-rays appeared to be factors 
for relatively few cases. Increased risk was associated with maternal contact 
with nitrosamine-containing substances such as burning incense (odds ratio, 3.3; 
p = 0.005), sidestream cigarette smoke (odds ratio, 1.5; p = 0.03), and face 
makeup (odds ratio, 1.6; p = 0.02); with maternal use of diuretics (odds ratio, 
2.0; p = 0.03) and antihistamines (odds ratio, 3.4; p = 0.002); and with the 
level of maternal consumption of cured meats (p = 0.008). These drugs contain 
nitrosatable amines and amides, and the cured meats contain nitrites, chemicals 
which are precursors of N-nitroso compounds. We propose a hypothesis that brain 
tumors in these young people are related to in utero exposure to N-nitroso 
compounds and their precursors, the most potent nervous system carcinogens known 
in experimental animals.