However, we were also wary of dangers not restricted to the water. Benzene, a predominant liquid hydrocarbon of concern, is poorly soluble in water. Still, some of the benzene gushing out from the well may be washed out in the water on its 5,000-foot journey to the surface, limiting human exposure, but potentially harming aquatic life. Because of its high vapor pressure, any benzene that does reach the surface of the Gulf is vaporized as soon as it hits the surface and is quickly released into the atmosphere in dilute concentrations. But benzene gas is heavier than air and can accumulate close to the water surface, further increasing exposure risk to workers at sea.
According to the United States Occupational Safety and Health Administration (OSHA), benzene is known to cause cancer in humans, and toxic levels have been linked to an increased risk of leukemia and heart and nervous system problems. OSHA has set the benzene permissible exposure limit at 1 part per million and a short-term exposure limit at 5 parts per million for 15 minutes. The CDC reports that breathing benzene at high levels can lead to drowsiness, irregular heartbeats, headaches, and with continued exposure or very high levels could result in unconsciousness or even death.
Although unsafe benzene levels were not detected at any point during our expedition, personalized full-face respirator masks with highly sensitive and effective filters for hydrocarbons and volatile gases were available on our dive vessel in the event unsafe levels were detected.
Fisherman turned cleanup crew are part of BP's "Vessels of Opportunity Program" -- a program started after the Deepwater Horizon accident which hires displaced fisherman and boats to assist with clean-up and response efforts. According to BP, 1,300 people have gone through the Vessels of Opportunity program so far, each receiving four hours of oil spill and safety training.
Although the EPA reports coastal monitoring of ozone and volatile organic compound levels has not revealed dangerously elevated levels so far, little information is available about the air quality at sea, where clean-up crews are most vulnerable. The EPA has reported normal ozone and particulate levels on the Gulf coastline as of May 24, 2010. Real-time air monitoring tests with trace atmospheric gas analyzers has not revealed elevated benzene, toluene or xylene gas along the Gulf coast or in New Orleans, but the same may not be necessarily true of the conditions at sea.
Despite news of ill clean-up workers, Chris Robertson, director of Environmental Health and Safety at Technical Environmental Services and part of the safety team on board ABC's dive vessel, reports there have been no elevated benzene or volatile organic compound levels recorded on the Gulf so far. His company is actively monitoring benzene levels at several remote sites in the Gulf as close as 10 miles away from the Deepwater Horizon accident site.