Some industrial chemicals which can damage the liver, kidneys and nervous system are often discharged into public water supplies. Currently tested water is considered pure if the amount of industrial chemicals an individual is exposed to, through drinking 2 liters of water per day does not pose a significant threat to human health. But many toxicologists claim that the standard set by this method does not adequately protect the public.
Which of the following if true would best support the claim of the toxicologists mentioned above?