Klein and other researchers made their determination using a new tool that measures an area's toxicity to honeybees, how long a pesticide remains toxic, and how much of it is used in a year, following procedures established by the U.S. Environmental Protection Agency. The study found that "neo-nics" accounted for 92 percent of the increased toxicity. "Neonics are not only incredibly toxic to honeybees, they can remain toxic for more than 1,000 days in the environment," Leahy reports.
Honeybees aren't the only animals affected; they are often a proxy for effects on other insects. And as insect populations have declined recently, so have the numbers of insect-eating birds, Leahy reports.
Neonics are used in more than 120 countries on over 140 different crops. In the U.S., it's most popular for coating seeds like corn or soy. But only 5 percent of the toxin stays on the plant; the other 95% builds up in the soil and environment, and has contaminated streams and other water sources, Leahy reports.