Residents of East Palestine, Ohio, have criticized the U.S. Environmental Protection Agency (EPA) for its response to the derailment of a Norfolk Southern train that released toxins including vinyl chloride — a plastic production chemical linked to liver cancer — into the town’s environment. 

Now, the EPA’s internal watchdog said it would investigate the agency’s handling of the disaster. 

“As part of this inquiry, we will conduct interviews, gather data, and analyze a variety of issues, including hazardous waste disposal, air and water monitoring, soil and sediment sampling, and risk communication,” the EPA Office of Inspector General (OIG) said in an announcement Monday. 

An agency spokesperson did not tell The Guardian why it chose to investigate. However, the EPA has faced many criticisms for how it conducted testing following the incident to make sure the derailment site and surrounding area were really safe for residents. 

“There are too many unanswered questions and conflicting information,” Kyla Bennett of Public Employees for Environmental Responsibility, who used to work as an EPA scientist, told The Guardian. “The IG can get to the bottom of how decisions were made to conduct testing the way they were and whether that was sufficient.”

One of the biggest controversies surrounding the government response to the derailment involved testing for dioxins. These are a type of toxic and persistent chemical present in Agent Orange, Stephen Lester of the Center for Health, Environment & Justice explained in an opinion column for The Guardian. 

“Dioxin is not deliberately manufactured. It is the unintended byproduct of industrial processes that use or burn chlorine,” Lester explained. 

So why didn’t the EPA test for dioxins immediately following the controlled burn of five-cars worth of vinyl chloride and other chemicals in the days after the derailment? Instead, it waited until March 2, nearly a month later, to announce it had instructed Norfolk Southern to test for dioxins. In response, more than 100 organizations signed a letter to the agency March 13 with recommendations on how testing should proceed, arguing that EPA should handle the testing itself and set up a transparent, comprehensive process open to public comment.

“Communities surrounding and downwind of the derailment have a right to know whether the fire resulted in elevated concentrations of dioxins,” the letter said. “The testing must be transparent and comprehensive. This would help demonstrate EPA’s commitment to comprehensively responding to this disaster, rebuilding trust with East Palestine and other impacted communities, and advancing environmental justice.”

Instead, the EPA allowed Norfolk Southern to proceed with the tests. Initial data from tests ordered by Indiana — whose landfill is storing East Palestine soil — revealed dioxin levels at hundreds of times the limit at which EPA scientists found they could cause cancer in 2010, though still below the federal action trigger, which was never updated after the findings, according to The Guardian. The EPA has maintained that levels so far are “similar to typical background levels,” as NBC News reported, but has not released any data of its own, claiming the final report will be ready within weeks. 

“I find it outrageous that EPA makes statements like this without providing any data to support it. There is no transparency in this process at all,” Lester told NBC News.

Beyond Plastics founder Judith Enck, herself a former EPA regional administrator, told the Pittsburgh Post-Gazette that the agency made two major missteps: delaying the test and putting Norfolk Southern in charge. 

“I know what the EPA is capable of,” she said. “There’s no question they should have been doing this themselves, and not hand it off to the company’s contractor because there’s already deep distrust within the community. The EPA needed to recognize that.”

Residents and advocates now hope the OIG investigation will provide some answers. 

“They’re not doing their job and everyone knows it,” Ohio River Valley Organizing Director Amanda Kiger told The Guardian. “For lack of a better term, it’s all a clusterfuck, but I’m hoping it’s a good investigation, and thorough.”