Two experiments were conducted in order to determine if challenge testing, a procedure developed by clinical allergists, could be used to provoke behavioral reactions to chemicals found in municipal waters. In one experiment, 10 male and 32 female volunteers tracked a moving target and monitored lights after
receiving sublingual drops that contained only water or varying amounts of sodium fluoride and nitrate. Dosage levels in this experiment equaled, exceeded, or fell below those found in municipal waters. In a second experiment, 20 females performed this task after receiving sublingual drops of the same test substances in a repeated measures design; dosage levels equaled or exceeded levels found in municipal waters by 100 or 500 times, Neither type nor amount of chemical affected primary task performance; however, after receiving sublingual drops in the first (between-subjects) experiment, subjects paid less attention to lights on their right. In the second experiment, subjects made more errors and had longer
response latencies after they received moderate and very high concentrations of the test substances. It was concluded that challenge testing is a safe but effective technique for provoking and studying reactions to chemicals when it is combined with a sensitive measure of sensorimotor performance.