Testing Pesticides on Humans

‘The dose makes the poison,” said 16th-century Swiss physician Paracelsus, and the modern approach to pesticides proves it. Chemicals for killing bugs and weeds are considered safe at low doses—so safe they have become a fixture of daily life. We eat pesticides on produce, drink them in groundwater, inhale them from flea collars, sprinkle them on lawns, and even spray them on our skin. Yet at high levels they are unquestionably dangerous. So at what dose do they become poisons? Toxicologists and government regulators have long relied on laboratory tests with rats and other animals to answer that question. The shortcomings of such tests are obvious: The results may not apply to people. But the alternative is to test pesticides directly on humans. And that’s just what pesticide manufacturers are doing. Over the past decade manufacturers have submitted to the Environmental Protection Agency results from more than a dozen experiments ...