Bats are considered a natural pesticide, widely relied on by farmers as an alternative to chemical pesticides to protect their crops from insects. But since 2006, many bat populations have collapsed in counties in North America due to an invasive fungus that causes White-Nose Syndrome. Harris Public Policy’s Eyal Frank uses the sudden collapse of bats to explore whether farmers turned to chemical pesticides, and whether doing so impacts human health.
Frank compared the effect of bat die-offs on pesticide use in counties that experienced those bat population declines to counties that were likely unaffected by the wildlife disease. He found that when the bat populations declined, farmers increased their use of pesticides by about 31 percent. Because pesticides have been linked to negative health impacts, Frank next tested to see if the increased use of pesticides corresponded with an increase in infant mortality—a common marker to study the health impacts of environmental pollution. Indeed, when farmers increased their use of pesticides, the infant mortality rate rose by almost 8 percent. This corresponds to an additional 1,334 infant deaths. Or, for every 1 percent increase in pesticides, there was a 0.25 percent increase in the infant mortality rate.