Genetically engineered crops, or GMOs, have led to an explosion in growers’ use of herbicides, with the result that children at hundreds of elementary schools across the country go to class close by fields that are regularly doused with escalating amounts of toxic weed killers.

GMO corn and soybeans have been genetically engineered to withstand being blasted with glyphosate – an herbicide that the World Health Organization recently classified as “probably carcinogenic to humans.” The proximity of many schools to fields blanketed in the chemical puts kids at risk of exposure.

But it gets worse.

Overreliance on glyphosate has spawned the emergence of “superweeds” that resist the herbicide, so now producers of GMO crops are turning to even more harmful chemicals. First up is 2,4-D, a World War II-era defoliant that has been linked to non-Hodgkin lymphoma, Parkinson’s disease and reproductive problems. Young children are especially vulnerable to it.

A new EWG interactive map shows the amounts of glyphosate sprayed in each U.S. county and tallies the 3,247 elementary schools that are located within 1,000 feet of a corn or soybean field and the 487 schools that are within 200 feet. Click on any county on the map to see how much GMO corn and soy acreage has increased there as well as the number of nearby elementary schools.

The 15 states outlined on the map across the center of the country are the ones where the Environmental Protection Agency has approved the use of Dow AgroSciences’ Enlist Duo – a combination of glyphosate and 2,4-D – on GMO corn and soybeans engineered to tolerate both weed killers.

The chart shows the 10 states with the most elementary schools within 1,000 feet of a corn or soybean field. These states account for 53 percent of the total acreage planted with genetically engineered GMO corn and soy. EPA has approved the use of Enlist Duo in seven of them.