Waterways along the Ohio River are still contaminated with hazardous materials following a train derailment that spilled multiple toxic chemicals, but officials are confident that those waterways are contained and not affecting water supplies, they announced during a press conference on Tuesday.
Four tributaries over a space of 7.5 miles are contaminated, director of Ohio Department of Natural Resources Mary Mertz told reporters during a news conference on Tuesday.
According to Mertz, the contaminated waterways has led to the deaths of at least 3,500 fish. Mertz also stated that officials have detected 12 different species of dead fish, but none of those species are threatened or endangered. There is also no evidence that non-aquatic species have been impacted.
However, there does not appear to be any increase in the number of fish killed since the initial derailment, Mertz said.
The Norfolk Southern Railroad train derailed in East Palestine, Ohio, on Feb. 3 while traveling from Illinois to Pennsylvania. It contained several types of hazardous materials, such as vinyl chloride, a highly volatile colorless gas produced for commercial uses, as well as ethylene glycol monobutyl ether, ethylhexyl acrylate and isobutylene, according to a list of the cars that were involved in the derailment and the products they were carrying released by Norfolk Southern.
No vinyl chloride or pre-product has been detected in the water, Tiffani Kavalec, chief of the Ohio Environmental Protection Agency's division of surface water, told reporters in Tuesday's news conference. The contamination mostly consists of fire contaminant combustion materials, Kavalec said.
Health officials are tracking a plume filled with contaminants that is currently floating down the river at about one mile an hour, Kavalec said. Around 3 p.m. on Tuesday, it was near Huntsville, West Virginia.
"There are very very low levels of volatile organic compounds in the Ohio River itself," she said. "It appears it's been very diluted."
The contamination dissipates to non-detectable levels near Little Beaver Creek, Kavalec said, adding it's not affecting the drinking supply for residents.
"We’re pretty confident that these low levels are not getting passed on to the customers," she said.
Bruce Vanderhoff, director of the Ohio Department of Health, advised residents who are living on private water systems to get their wells tested, especially if they are pregnant, breastfeeding or preparing baby formula.
Most of the residents in East Palestine are on municipal water, Vanderhoff said.
Surveillance video of the crash appears to show a wheel bearing in the final stage of overheat moments before the derailment, the National Transportation Safety Board announced on Tuesday in a press release.
Following the crash, emergency response teams worked to immediately slow the contamination of waterways from the runoff, while firefighters worked to extinguish the blaze, DeWine said.
For days, large plumes of smoke containing vinyl chloride, phosgene, hydrogen chloride and other gases were emitted during a controlled release and burn at the crash site, prompting officials to issue mandatory evacuation orders for homes and businesses within a 1-mile radius.
DeWine decided that the controlled burn was the best course of action after he was advised that a catastrophic explosion was likely, which would result in shrapnel being flung out for up to a mile from the site, he said.
"My objective is to do everything we can to get this cleaned up as quickly as we can," the governor said.
The hazardous materials that burned in the wreckage of the train derailment in Ohio had the potential to be deadly if evacuations not been ordered, experts told ABC News last week. Residents living in nearby homes were contacted at least three times before the controlled burn began, Dewine said.
The evacuation orders were lifted on Feb. 8 after air and water samples taken the day before were deemed safe, officials said.
There were 20 total hazardous material cars in the train consist,10 of which derailed, according to the NTSB. Five of the 10 cars containing toxins also contained vinyl chloride, officials said.
A total of 38 cars derailed, which caused a fire that damaged an additional 12 cars, according to the NTSB.
The train was not considered a "high hazardous material train," and therefore the railroad was not required to notify state officials about what the cars were containing, DeWine said.
"If this is true, and I’m told it’s true, this is absurd," Dewine said. "We need to look at this. Congress needs to look at how these things are handled."
The tank cars are currently being decontaminated, according to the NTSB. Once the decontamination process has completed, NTSB investigators will return to Ohio to complete a thorough examination of the tank cars.
No detections of vinyl chloride or hydrogen chloride were identified for the 291 homes that had been screened, according to the EPA. As of Monday evening, 181 homes remained to be screened. Local schools and the library were screened yesterday, the EPA announced.
The fume inhalation of vinyl chloride could cause dizziness, nausea, headache, visual disturbances, respiratory problems and other health-related issues, Ashok Kumar, a professor in the University of Toledo's department of civil and environmental engineering, told ABC News last week.
Hydrogen chloride fumes could irritate the throat and cause skin problems, while phosgene fumes may lead to chest constriction and choking, Kumar said.
Vanderhoff emphasized that volatile organic compounds are a part of "everyday life" and are typically inhaled if in the presence of burning wood or natural gas or someone who is smoking.
"Most people can be around these volatile organic compounds at low levels without really feeling health effects," he said. "At higher levels, especially over a longer period of time, then we can have longer-term health effects."
Norfolk Southern announced in a statement Tuesday that it has helped 1,000 families as well as a number of businesses in the community. The railway operator has also distributed $1.2 million to families to cover costs related to the evacuation.
Alan Shaw, the CEO Norfolk Southern, pledged that the railway operator would guarantee the cleanup from the accident, Dewine said.
A lawsuit filed by two residents of East Palestine on Feb. 9 called for the rail operator to pay for medical screenings and related care for anyone living within a 30-mile radius of the crash site, as well as undetermined damages, The Associated Press reported.
"Norfolk Southern is responsible for this problem," DeWine siad. "We fully expect them to live up to what the CEO committed to me. Is that they will pay for everything."
The NTSB is conducting a safety investigation to determine the probable cause of the derailment, the agency said.
ABC News' Amanda Maile and Peter Charalambous contributed to this report.