Risk of Childhood Brain Tumors in Relation to Paternal Smoking Level during pregnancy by Polymorphisms in Selected Genes, West Coast Childhood Brain Tumor Study, Born 1978–1990.

aHours of exposure per day.bAdjusted for race, sex, age at diagnosis/reference, mother’s education, birth year and center.cAdditionally adjusted for maternal smoking.dInteraction between genotype and smoking, using hours of exposure per day (interaction for trend).eMicrosomal epoxide hydrolase (mEH) activity: low–0,1 or 2 stable alleles (HH/HH, HH/HR, HY/HH, HH/RR, HY/HR, YY/HH); high–3 or 4 stable alleles (HY/RR, YY/HR, YY/RR).