Cities Are Worried About the Health Effects of Glyphosate

When invasive Himalayan blackberry creeps into one of Seattle’s wooded parks, it takes over, conquering native plants. In the past, Seattle park managers may have sprayed the noxious plant with the weed killer Roundup. But Seattle is the most recent in a wave of U.S. cities turning away from Roundup because of growing concern that it could be giving people cancer.

Roundup’s active ingredient, glyphosate, has helped grow food and stamp out weeds since it was introduced by Monsanto in 1974. Its popularity swelled in the 1990s, when Monsanto began also to sell specially designed crop seeds, including soybeans, canola, and corn, that could withstand the herbicide when it was sprayed on surrounding weeds. The company’s patent on glyphosate expired in 2000, and then other companies entered the market; today, several hundred products for sale in the U.S. contain glyphosate.