WILLOWBROOK (WLS) -- New testing by the U.S EPA shows there's been a rapid drop in a cancer-causing chemical days after the closure of the Sterigenics plant in DuPage County.
RELATED: Willowbrook Sterigenics plant shut down Friday night
The medical supply sterilization company, which has been in Willowbrook since 1984, was forced to shut down last month after testing showed dangerous levels of ethylene oxide in the air in a radius around the Sterigenics plant.
Following the shutdown, the company filed an emergency request for temporary restraining order that would allow the facility to reopen, but a judge denied the request.
RELATED: Judge denies Sterigenics temporary restraining order, Willowbrook facility remains closed
Since then, the most recent tests show ethylene oxide levels were at least 50 to 90 percent lower after the shutdown.
Thursday, Sterigenics released a statement claiming the results also prove there are other sources emitting ethylene oxide besides its facility.
"Ethylene oxide (EO) detection levels released by the U.S. EPA [Thursday] demonstrate the existence of EO in the ambient air in Willowbrook despite the fact that the Sterigenics facility remained closed," the stated read.
RELATED: Water tested for cancer-causing chemical near Sterigenics plant in Willowbrook
However, Congressman Dan Lipinski's (IL-3) office also issued a release Thursday stating "Sterigenics is clearly the culprit," and persists the plant remain shut down.
"The health and safety of the people that live, work, and go to school near Sterigenics must be protected," said the statement from Lipinski's office.
"Sterigenics has a proven track record of complying with and going about and beyond what the regulations require in the safe use of EO to sterilize critical medical produces and devices," Sterigenics officials said.
RELATED: Group releases 1984 EPA letter about cancer-causing chemical in Willowbrook
EPA tests: Rapid drop in cancer-causing chemicals following Sterigenics closure