Two Salem County, N.J., chemical plants that require shipments of vinyl chloride have temporarily shut down as a result of last month's train derailment in Paulsboro, which spewed the toxic chemical into the air and blocked a critical railroad bridge, a chemical trade association said Friday.

As many as 400 people are employed at the OxyVinyls and PolyOne Corp. plants in Pedrickstown, according to the association. The companies use vinyl chloride to make and distribute products including plastics, pipes, and floor materials.

Attempts to reach the companies Friday were unsuccessful.

Representatives from about 30 Gloucester County businesses dependent on shipments on the now-closed CSX rail line met Friday with officials from Conrail and the unified command leading the cleanup effort. The companies were eager to learn when trains might again cross the Mantua Creek bridge, where seven cars derailed Nov. 30.

The businesses employ a total of about 5,000 people, a county official said.

"When the artery is cut, there's a cascading series of negative events," said Hal Bozarth, executive director of the Chemistry Council of New Jersey, a trade group whose members include OxyVinyls and PolyOne.

Chemical plants typically stockpile a week's worth of material, Bozarth said. Sixty trains would ordinarily have passed through Paulsboro in the two weeks since the derailment, he said.

"People are waiting for an awful lot of material," Bozarth said.

Companies that own more than one plant can divert manufacturing when one cannot operate, he said. But any plants that close risk permanently losing product lines, which could give the parent company an excuse to move out of New Jersey.

Heading into the day's meeting, some expected the rail line to resume operation as early as Monday. There is no alternative rail route, a county official said.

But neither Conrail nor the command, which is led by the Coast Guard, would provide a timeline, said Lisa J. Morina, Gloucester County director of economic development, who attended the meeting.

"We appreciate that this incident has been a challenge for businesses served by Conrail. We are working with them now - and will continue to work with them once service is restored - to help get their products efficiently and safely to market, and help them get the materials that they need," Conrail spokesman Michael Hotra said in a statement.

Cleanup crews and engineers are still working to remove railcars from the creek. Most of the 700 residents who were evacuated have returned home, and no one is believed to have been seriously injured.

On Friday, workers extracted two cars from the water, putting one on a barge and setting the other back on the rails. Coast Guard Capt. Kathy Moore had described one of the cars as logistically the most dangerous of the four submerged cars to be lifted from the water.

The breached car, which needed to be cleansed of vinyl chloride before it could be safely handled, was removed Tuesday.

Two tankers remain in the water - one containing ethanol, the other vinyl chloride - as workers also repair the rail tracks.

"The unified command is very pleased with where they are" with the repairs, Coast Guard spokesman Nick Ameen said. "The progress they've made is right where they want to be."

At the meeting, companies expressed concern about how their needs would be prioritized when the CSX line reopens. "Whose product is on what railcar?" Morina asked. "Whose product gets delivered first?"

She said the businesses recognized that some were hurting more than others. But Conrail has not communicated its prioritization strategy well, said Steve Chranowski, the Chemistry Council's director of regulatory affairs.

"These companies are trying to plan. They want to know what's going on. They were hoping to get answers today. We're optimistic that no one's going to have to go off-line," Morina said.

DuPont has a plant in Pennsville, Salem County, that is drawing on its inventory of materials, company spokesman Nate Pepper said. "It is critical to our business that the rail line to DuPont Chambers Works is reopened as soon as it is safe to do so," he said.

Contact Andrew Seidman at 856-779-3846, aseidman@phillynews.com, or follow on Twitter @AndrewSeidman.