NEW YORK - For days, authorities have been telling residents of the area around East Palestine, Ohio, the United States, that it is safe to return home after a 150-car train carrying hazardous chemicals derailed Feb 3, NBC News reported Monday.

But one resident told local media that her five hens and rooster died suddenly last Tuesday. The day before, rail operator Norfolk Southern had burned train cars carrying vinyl chloride, a flammable gas, to prevent an explosion, the report said.

The Ohio Department of Natural Resources said the chemical spill resulting from the derailment had killed an estimated 3,500 small fish across 7.5 miles (about 12 km) of streams as of last Wednesday.

"For some people who live near the derailment site, the reports continue to spur fear that they and their animals might be exposed to chemicals through the air, water and soil," said the report.

After the controlled burn, the Environmental Protection Agency (EPA) warned area residents of possible lingering odors but noted that the byproducts of vinyl chloride can emit smells at levels lower than what is considered hazardous.

The EPA classifies vinyl chloride as a carcinogen; routine exposure could increase one's risk of liver damage or liver cancer. Short-term exposure to high concentrations can cause drowsiness, loss of coordination, disorientation, nausea, headache or burning or tingling.