The swarms were so thick they obscured the sun. Mohammed Adan, a farmer in northeastern Kenya, watched the horde of desert locusts first descend in late 2019. He’s been grappling with their legacy ever since.

While locust swarms spread across 10 countries over the course of early 2020, Kenya was particularly hard hit — one of the swarms feeding off the country stretched to three times the size of New York City. Three million people across the country, many of them small-scale farmers, were at risk of losing their entire season’s harvest. A legion of international organizations, including the United Nations’ World Food Programme and Food and Agriculture Organization, or FAO, marshaled support in collaboration with Kenya’s Ministry of Agriculture. Throughout the locust invasion, the FAO raised more than $230 million, which allowed it to acquire 155,600 liters of synthetic pesticides that were used to treat nearly 500,000 acres.

To handle ground-spraying operations, the Kenyan government enlisted both its army as well as members of the National Youth Service, a voluntary, government-funded vocational and training organization for young Kenyans. Meanwhile, the FAO contracted charter airline companies to conduct aerial spraying. An issue of apocalyptic scale required all hands on deck.

Farmers like Adan were relieved that the government and aid organizations were stepping in to help. “We wanted those pesticides,” he told Grist. “Otherwise, we would have lost everything.”

But Adan didn’t know at the time that the FAO and other humanitarian groups had procured pesticides that were either already banned in the U.S. and Europe or soon would be. The synthetic pesticides in question — part of a chemical class known as organophosphates that includes chlorpyrifos, fenitrothion, malathion, and fipronil — have been known to cause dizziness, nausea, vomiting, watery eyes, and loss of appetite in humans who come into contact with them. Long-term exposure has been linked to cognitive impairment, psychiatric disorders, and infertility in men.

Read the full article about harmful pesticide use in Kenya by Kang-Chun Cheng at Grist.