West Nile Spraying Safe in Short Term: Study
California researchers found Sacramento County residents had no immediate health problems after pesticide was applied
To make sure her comparisons were accurate, Geraghty tested them in a couple ways. For example, to make sure she wasn't overlooking any unknown diagnoses related to pesticide exposure, she compared all emergency-room diagnoses against visits for fractures and dislocations -- problems that couldn't possibly be related to spraying. "We found essentially nothing significant," she said.
She also performed a sensitivity analysis using ozone levels, to see if high ozone caused more emergency-room visits. "We could see a correlation between ozone and asthma, so I suspect if there had been a correlation with pesticides, we would have seen that as well," Geraghty said.
These findings might not apply elsewhere in the United States, where mosquito-control programs are run differently, she said.
For example, the Sacramento County program uses ultra-low-volume spraying to minimize pesticide exposure to people, with only three-quarters of an ounce or less of pyrethrin applied per acre.
"They are using the smallest effective amount of pesticide possible, about a shot glass per acre," Geraghty said. "When you think of it that way, it's a very, very small amount."