IN the fall, I began to research an article that I gave the working title “The Last Days of Chlorpyrifos.” A widely used pesticide, chlorpyrifos affects humans as well as the bugs it kills. Back in the halcyon days before the election, the optimism of the title seemed warranted. After years of study, the Environmental Protection Agency had announced in October 2015 that it could no longer vouch for the safety of chlorpyrifos on food.

The agency had acknowledged for decades that chlorpyrifos can cause acute poisoning and in the early 2000s it had prohibited its use in most home products and reduced the amounts that could be used on some crops. But the 2015 announcement stemmed from the agency’s recognition of mounting evidence that prenatal exposure to chlorpyrifos could have lasting effects on children’s brains.

Though the process of re-evaluating the safety of the pesticide had stretched on for years, at long last, chlorpyrifos seemed to be going down. Another report was expected to provide all the ammunition necessary to stop its use on fruits and vegetables, and I was eager to document its demise. For a reporter who covers the environment, this was going to be the rare happy story.

The election of President Trump has thrown that outcome — indeed, the fate of many of the E.P.A.’s public health protections — into question. On Monday, Mr. Trump signed an executive order requiring federal agencies to scrap two regulations for every one they institute on small businesses. In its first week, his administration suspended 30 environmental regulations issued under President Barack Obama. And Myron Ebell, who oversaw the agency’s transition team, suggested recently that the E.P.A.’s staff may soon be reduced by as much as two-thirds.