(NewsNation) — The rainbow sheen observed in creekbeds following the train derailment near East Palestine, Ohio, appears to be from a class of chemicals commonly found in adhesives, paints and plastics, according to a new report from an environmental consulting firm.

Pittsburgh-based Big Pine Consultants tested the water in multiple areas two weeks after the derailment and observed hydrocarbon sheen “flashes” at Leslie Run similar to those Ohio Sen. J.D. Vance had drawn attention to.

“The ORO (oil range organics) is likely to be the cause of the surface sheen and fish kill that occurred,” the environmental firm determined.

At Leslie Run, Big Pine did not detect any vinyl chloride — the hazardous material had been found inside five tanker cars and was burned by authorities following the derailment.

Based on results from the Ohio Environmental Protection Agency, the exact chemicals may be butyl acrylate or ethylhexyl acrylate, Big Pine concluded. Both compounds were reported to be in some of the rail cars and can cause skin irritation, eye irritation and respiratory irritation, according to the National Institutes of Health.

“Stirring stagnant sediment from any body of water has the potential to create a sheen,” the Ohio EPA wrote after videos of the oily creek bed went viral. “We are not seeing these contaminants in the water itself unless the sediments are disturbed.”

The Ohio EPA is continuing to clean creek sediment and says the water is not the source of the municipal water supply in East Palestine.

During its collection almost one month ago, Big Pine did not observe fish or other life in Leslie Run. It remains to be seen whether the natural wildlife will return in the future.

“As the area is cleaned, the stream may recover,” Big Pine wrote in its report.

Dilution appears to have reduced the concentration of the ORO compound to below minimum detectable levels downstream, the environmental firm noted.