Table 2.

Results of logistic regression models of iAs exposure by quintile and BCC in the ASHRAM study population [OR (95% confidence interval)].

Arsenic exposure index/quintile (range of exposure in controls)	Adjusteda	Additionally adjustedb	Trend test (p-value)
Lifetime average iAs concentration (μg/L)						0.001
0.00–0.68		1.00		1.00
0.68–0.98		1.27 (0.82, 1.97)		1.39 (0.89, 2.19)
0.98–7.00		1.02 (0.67, 1.56)		1.20 (0.77, 1.88)
7.10–19.43		1.63 (0.93, 2.85)		1.73 (0.97, 3.11)
19.54–167.29		2.81 (1.62, 4.87)		3.03 (1.70, 5.41)
Peak daily iAs dose rate (μg/day)						0.001
0.00–0.73		1.00		1.00
0.73–1.48		0.93 (0.62, 1.39)		0.91 (0.59, 1.39)
1.48–9.09		1.29 (0.86, 1.95)		1.55 (1.00, 2.41)
9.09–32.23		1.78 (1.05, 3.02)		1.76 (1.01, 3.07)
32.23–242.14		2.31 (1.32, 4.03)		2.50 (1.39, 4.49)
Cumulative iAs dose (g)						0.001
0.00–0.01		1.00		1.00
0.01–0.03		1.02 (0.68, 1.52)		1.09 (0.72, 1.67)
0.03–0.13		1.19 (0.78, 1.81)		1.46 (0.93, 2.27)
0.13–0.55		1.73 (1.02, 2.91)		1.76 (1.02, 3.04)
0.55–4.46		2.45 (1.39, 4.32)		2.63 (1.45, 4.78)
Relative risks of BCC were estimated as ORs comparing risk of cancer in a quantile with the quintile of lowest exposure. Range of iAs exposure within each quintile is expressed in the unit of measure specific for each exposure index. aAdjusted for county, age, and sex, based on n = 1,022 for peak dose rate, n = 1,025 for lifetime average concentration, and n = 1,011 for cumulative dose. bAdditionally adjusted for education, skin response to 1-hr midday sun, and skin complexion, based on n = 989 for peak dose rate, n = 992 for lifetime average concentration, n = 979 for cumulative dose.