Table 1.

Risk factors investigated in studies of WBC DNA global methylation by assay type

	Some support for lower global methylation	Little to no support of an association with global methylation	Some support for higher global methylation
Demographics
Age	%5-mC 33 [3H]-methyl35 LINE-1 36 Alu34,36,37,41	%5-mC18 LINE-1 17,21,37–41
Gender (Females versus Males)	%5-mC33 LINE-1 17,21,37–39,46 Alu46	%5-mC18 LINE-1 41 Alu41	LUMA 46 Alu37
Race (Black versus White)	[3H]-methyl 53 LINE-1 39	CCGG 54	LINE-1 21
Environmental factors
Benzene	LINE-1 55 Alu55
Persistent Organic Pollutants	LINE-1 57 Alu41,57	LINE-1 41
Lead	LINE-1 58,59 Alu58	Alu59
Arsenic			[3H]-methyl 35
Air Pollution	LINE-1 62–64 Alu62,64	Alu63
Behavioral Risk Factors
Adult Active Cigarette Smoking		%5-mC18,20 CCGG68 LINE-1 17,21,37,41,57,69 Alu37,41,57
Prenatal Cigarette Smoking	LINE-1 73 Sat273	Alu73	[3H]-methyl53
Alcohol Drinking	Alu37	LINE-1 21,37,41,79 Alu41	CCGG77,78
Higher Body size	LINE-1 80	LINE-1 37,41,79 Alu 37,41
Higher Physical Activity			LINE-1 79
Low Dietary Folate		%5-mc18,81 LINE-1 21,79 Alu79