Table 4.

Association Between Lifetime Arsenic Concentration and Risk of Basal Cell Carcinoma, Stratified for Haplotype (Logistic Regression)

		Effect estimatesa
Haplotype	N	P	OR	95% CI		Effect modificationb
Haplotype 1						0.036
0 copies	239	0.001	1.4	1.1	1.8
1/2 copies	782	0.045	1.1	1.0	1.2
Haplotype 2						0.098
0 copies	805	<0.001	1.2	1.1	1.4
1/2 copies	216	0.85	1.0	0.9	1.2
Haplotype 3						0.43
0 copies	719	0.072	1.1	1.0	1.2
1/2 copies	302	<0.001	1.4	1.2	1.8
Haplotype 4						0.58
0 copies	809	0.004	1.2	1.1	1.3
1/2 copies	212	0.025	1.3	1.0	1.6
Haplotype 5						0.054
0 copies	894	0.006	1.1	1.0	1.2
1/2 copies	127	0.082	1.3	1.0	1.8
Haplotypes 1 and 2						0.010
0 and 0 copies	140	0.001	2.7	1.5	4.8
0 and 1/2 copies	99	0.99	1.0	0.7	1.4
1/2 and 0 copies	665	0.040	1.1	1.0	1.3
1/2 and 1/2 copies	117	0.95	0.99	0.8	1.2
Haplotypes 1 and 4						0.020
0 and 0 copies	139	0.012	1.6	1.1	2.2
0 and 1/2 copies	100	0.014	1.5	1.1	2.0
1/2 and 0 copies	670	0.041	1.1	1.0	1.2
1/2 and 1/2 copies	112	0.79	1.1	0.7	1.6
Haplotypes 2 and 4						0.26
0 and 0 copies	618	0.003	1.2	1.1	1.3
0 and 1/2 copies	187	0.006	1.5	1.1	1.9
1/2 and 0 copies	191	0.52	1.1	0.9	1.3
1/2 and 1/2 copiesc	25

CI = confidence interval, OR = odds ratio, N = number of individuals.

^aModel included life time arsenic concentration (per 10 µg/L increase), skin complexion, skin response to 1-hr midday sun, age, gender, education, and county.

^bA separate model that included all individuals provided the P value for the effect modification (the interaction term haplotype × life time arsenic concentration).

^cToo few individuals to conduct any analyses.