3 studies have now been completed. The 1st, an uncontrolled dose-response eval showed a slight increase in tot. cholesterol and tot. thyroxine with exposure to 5 and 10 ppm chlorine in drinking water. The 2nd, which involved a controlled eval. of 20 ppm drinking water chlorine in women, showed no effect of chlorine on either lipid or thyroid metabolism. The 3rd protocol is identical to the controlled protocol just cited except the subjects are used as their own controls as well as to a separate control group.