This post has been updated.

All 125 commercial vessels working to clean up the oil spill in the Gulf of Mexico have been ordered back to shore temporarily after four workers on three separate vessels became ill, according to a Deepwater Horizon Response press release.

It's unclear whether the crew members were working with chemical oil dispersants, which have been criticized for their toxicity. Our calls to officials in the region have not yet been returned.

The sick workers said they had headaches and chest pain, and were nauseated and dizzy. One was taken by helicopter to a hospital in Marrero, La., another was taken by boat and two were taken in an ambulance, according to the press release.

The current symptoms mirror those of other fishermen who were hired by BP to help clean up the spill, as we pointed out earlier this week. The dispersants BP is using to break up the oil have many health risks of their own. Earlier this month, the EPA told BP to stop using the chemicals and to switch to something else, but BP says there is no better alternative.

Update, 5/27:

According to Captain Meredith Austin, the Coast Guard deputy incident commander, controlled burns were being executed and aerial dispersants were being used in the vicinity of the affected workers, but no dispersants were being sprayed within 50 miles of the workers.

"It's important to keep in mind there are other factors which may potentially cause these symptoms," Austin told reporters on a conference call this evening. She named the smell of petroleum, heat and fatigue as possible causes for the symptoms.

Workers were not given respiratory protection equipment because according to Austin, prior air sampling performed in the area concluded that the level of chemical exposure was permissible.