The Nov. 25 industrial accident that shut the Delaware Memorial Bridge for seven hours and snarled post-Thanksgiving traffic on the New Jersey Turnpike and I-95 released more than a ton of ethylene oxide, a highly flammable liquid known to cause cancer, officials of the plant’s owner, United Kingdom-based Croda, said Thursday.

The information was shared by Bob Stewart, managing director of operations for Croda, at a public meeting attended by around 125 neighbors of Croda’s Atlas Point complex, who asked state officials to explain why dangerous industrial plants are allowed so close to busy highways and residential neighborhoods.

The plant, built in 1937, “has been safely handling ethylene oxide since the 1940s,” said marketing director Cara Eaton. Five workers sought medical attention after the accident.

The 2,688 pounds of gas that Croda reported leaked after an “incorrect” gasket failed is about what the ethylene oxide facility could produce in 40 minutes, according to data that company officials gave on a tour of the facility the week before the accident. The company uses the material to produce surfactants, including mixing and separating agents for many industrial and retail products made by other chemical companies and corporate customers. State officials said they are still reviewing how much ethylene oxide, which they referred to as a gas, escaped.

Croda had hoped to restart the plant as soon as two weeks after the accident but instead is continuing the investigation. The company has kept its 250-member staff working, including 35 members hired for the now-closed unit.

Some of the ethylene oxide, which government agencies list as a carcinogen to people who are exposed to it for long periods, was washed away and dissipated harmlessly as company, volunteer, and state emergency responders sprayed more than a million gallons of water on the plant and its supply pipes.

And some leaked into the ground and is being monitored by the company, which is keeping the state informed of its findings, state and company officials said at the meeting, according to accounts in the Wilmington News Journal and on WDEL radio.

“The ethylene oxide was substantially contained by the water deluge,” Eaton said after the meeting. “The incorrect gasket is one of over 400 used on the unit, fitted on one of the pipes during the plant construction, and we are systematically reviewing each one, alongside other equipment, to ensure the correct gaskets and other fittings are in place.” She said the company has “completed over 90 percent of this inspection and have not found another incorrect gasket.”

But the ethylene oxide manufacturing facility, Eaton said, will remain closed for the remainder of the investigation "and to carry out our systematic review and any necessary work to prevent such an incident happening again. The facility will be operational as soon as possible, but not until external specialists and regulatory authorities have advised that it is safe to do so. "

According to the National Institute for Occupational Safety and Health, ethylene oxide may cause harm following exposure through inhalation, or skin or eye contact. Short-term exposure can cause nausea, headache, weakness, vomiting, and drowsiness. Skin contact can cause blisters, swelling, burns, frostbite, and severe irritation. Long-term chronic exposure can numb the sense of smell and lead to respiratory infection, anemia, and nerve damage. Chronic exposure has been linked to leukemia and stomach cancer, as well as miscarriage.

Croda in 2016 said it would spend $170 million building the new unit at the plant complex. But Stewart, on a tour of the plant before the accident, would not confirm what Croda actually ended up spending — whether the company had reduced the cost of the original plan or had ended up spending more than it expected.

The company asked state permission to reduce the size of some of the structures on the site in a revised permit application filed last summer, according to Delaware Department of Natural Resources and Environmental Control records.

The plant made ethylene oxide from relatively stable ethanol (the same alcohol that makes you drunk). Stewart and other Croda officials said that’s an environmentally friendlier process than older ways of synthesizing the volatile chemical and hauling it to the site in rail cars from manufacturers in the Houston area and other distant centers. But Croda has had to go back to rail-car shipping with its new unit shut down.

Neighbors at Thursday’s meeting questioned why state officials allowed the production, use and storage of volatile and hazardous chemicals near highways and bridges that carry over 80,000 commuters and long-range drivers a day, and near residential neighborhoods.

But the Atlas plant has been at that location since the 1930s, before the twin bridges were built, and has been using ethylene oxide under Croda’s predecessors, including Uniqema, which operated the plant and occupied a neighboring office building, now vacant, in the early 2000s.

Delaware’s recent Democratic governors have supported industry plans to update the aging chemical plants that line the west bank of the river between the Pennsylvania state line below Marcus Hook and the Chesapeake and Delaware Canal in Delaware City, in the hope of keeping relatively well-paid blue-collar jobs for their constituents and ensuring that the chemical industry still has a home in the area, close to many of its customers in the northeastern United States.

Political leaders have felt pressure to ease the way for heavy industry, following the loss of thousands of factory jobs in the closing of the state’s General Motors and Chrysler automotive assembly plants, shutdowns by the DuPont Co. and its spin-off companies, and the demolition of the Claymont Steel (Evraz) mill in the past 10 years.

The administration of Gov. John Carney and the ruling Democrats in the state legislature this year agreed to relax provision of the state coastal-zone act to make it easier to build and expand heavy industry along the Delaware River and Bay shoreline after a long moratorium. But the Thanksgiving-weekend accident at Croda has energized environmentalists, who claim the chemical industry is not compatible with the region’s suburban sprawl.

Staff writer Marie McCullough contributed to this article.