(NewsNation) — The U.S. Environmental Protection Agency told residents near the toxic train derailment in eastern Ohio that it is safe to return home, but residents are alarmed and have concerns, as fish in local bodies of water are dying.

About 50 cars, including 10 carrying hazardous materials, derailed on Feb. 3 in the Ohio village of East Palestine. No one was injured in the derailment that investigators said was caused by a broken axle.

Three days after the accident, authorities burned vinyl chloride inside five tanker cars, sending hydrogen chloride and the toxic gas phosgene into the air. They said that burn was preferable to the threat of a larger explosion if nothing was done.

Environmental regulators have been monitoring the air and water in surrounding communities and have said that so far the air quality remains safe and drinking water supplies have not been affected.

But some residents have complained about headaches and feeling sick since the derailment.

Authorities warned the burning vinyl chloride that was in five of the derailed cars could send hydrogen chloride and phosgene into the air.

NewsNation affiliate WKBN spoke with hazardous material specialists who said some of the chemicals released are carcinogens.

“There’s a lot of what ifs, and we’re going to be looking at this thing 5, 10, 15, 20 years down the line and wondering, ‘Gee, cancer clusters could pop up, you know, well water could go bad,” said Silverado Caggiano, a hazardous materials specialist.

NewsNation also obtained video of dead fish in the Ohio river near East Palestine. Residents said they’ve also seen sick animals and their homes and town are still covered in debris.

It’s possible the pollution lowered dissolved oxygen levels in the water, basically suffocating the fish, but that hasn’t been confirmed, according to Wildlife Officer Supervisor Scott Angelo.

The Ohio Department of Natural Resources will still need to evaluate what caused the fish to die, which could take up to a month while the agency deals with the emergency response.

The EPA says hundreds of tests have been performed confirming the water and air are in good living condition.

“The vinyl chloride: I know that’s the most common thing heard right now. That was below the detectable limit,” said Scott Wolfe, superintendent for East Palestine Water and Wastewater.

The Centers for Disease Control and Prevention warns that breathing the gas over long periods of time could be connected to brain, lung, and blood cancers.

Renowned consumer advocate Erin Brokovich told NewsNation said she doesn’t believe those tests, and residents should be taking pictures and videos of everything they see.

“After 30 years of what I’ve been through and what this community is going through, they know. Come on, it’s vinyl chloride, it’s in the air, the fish are dying. Really? Does that give you comfort that you should be in the area? Probably not,” said Brockovich.

East Palestine Police said they are going door to door to check at risk homes that drink their water from wells in the area.

Meanwhile, residents have filed a federal lawsuit seeking to force Norfolk Southern to set up health monitoring for residents in Ohio and Pennsylvania.

The lawsuit, filed Thursday by two Pennsylvania residents, calls for the rail operator to pay for medical screenings and related care for anyone living within a 30-mile radius of the derailment to determine who was affected by toxic substances released after the derailment. The lawsuit also is seeking undetermined damages.

The Associated Press contributed to this report.