^a Odds ratio calculated without consideration of possible confounders (ratio of exposed to unexposed cases divided by the ratio of exposed to unexposed controls).

^b 95% confidence intervals for the odds ratio calculated without consideration of possible confounders.

^c Odds radio adjusted statistically for possible confounding factors.

^d Corresponding confidence intervals calculated for the odds ratio adjusted for possible confounding factors.

^e Includes all factors considered to be potential confounders whether or not statistical adjustments were made for them.

^f HCC, high current configuration.

^g LCC, low current configuration.

^h Cases expected on the basis of incidence data for the disease in the general population.