In the face of every toxic threat that humans have yet created, here is a realization that is equally optimistic and discouraging: humans needn't fear science; but we should be terrified by the lies we tell ourselves about the good and bad things that human "mastery" of science can bring.
This point struck me as I was reading Rick Smith and Bruce Lourie's excellent book, Slow Death by Rubber Duck. As the lighthearted title suggests, this is a jaunty walk through the horrors of chemical poisoning - a very personal voyage of discovery by the authors, who actually arranged for themselves typical exposures to the kinds of cancer-causing chemicals that all of us might run into on any particular day.
Their conclusion (minor): risks lurk around every corner. Their conclusion (major): Our failure to recognize and regulate those risks is not based on a lack of knowledge. It's based on a high degree of societal recklessness that flows directly from leaving the chemical salespeople in charge of risk management. The chemical and pharmacological industries' profit-driven public relations is trumping our efforts to make prudent judgments about our health and safety.