Legislator: To keep our food safe, we must prohibit the use of any food additives that have been found to cause cancer  Commentator: An absolute prohibition is excessive  Today' s tests can detect a single molecule of potentially cancer-causing substances, but we know that consuming significantly larger amounts of such a chemical does not increase one' s risk of getting cancer
Thus, we should instead set a maximum acceptable level for each problematic chemical, somewhat below the level at which the substance has been shown to lead to cancer but above zero
Consuming small amounts of several different cancer-causing chemicals can lead to cancer even if consuming such an amount of any one cancer-causing chemical would not.