Relative risks of BCC were estimated as ORs for unit changes
in exposure: a 10 μg/L increase in lifetime average iAs concentration, a
10-μg/day increase in peak iAs daily dose rate, or an increase in
cumulative iAs dose derived from 50 years of drinking 1.5 L water/day
containing 10 μg/L iAs. aMedian DMA%, 76.6%; median MA%, 15.8%. bThese
ORs are stratum specific because they estimate effect of iAs on cancer
as a linear effect, separately by level of metabolite, for both DMA% and
MA%, and controlled for potential confounders county, age, sex,
education, skin response to 1-hr midday sun, and skin complexion.
cp-Values for multiplicative interaction terms between dichotomous
variables for DMA% or MA% and continuous variables for iAs exposure
indexes (Wald test). |