At least nine oil workers have died since 2010 from inhaling toxic amounts of vapors while measuring crude oil in storage tanks at well sites, according to new findings by federal researchers.
The National Institute for Occupational Safety and Health report, posted Friday, documents a poorly understood hazard in the oil field from volatile hydrocarbons, also called volatile organic compounds, or VOCs. Many oil workers and supervisors don't realize the petrochemicals can kill (EnergyWire, Oct. 27, 2014).
"These deaths are tragic -- especially since they can happen suddenly and without warning," said Robert Harrison, an occupational medicine physician at the University of California, San Francisco, who has been researching such deaths. "It is very important that safety programs are in place to prevent workers from breathing toxic chemicals when they gauge or sample tanks."
All crude oil has compounds called volatile hydrocarbons such as benzene, butane and propane. Shale crude sometimes has more of these compounds than conventional oil. It's related to why shale oil is more prone to explode in rail cars. The chemicals bubble up from the crude oil and collect in storage tanks.
"These conditions could occur due to high concentrations of gases and vapors inside the tank which are released in a burst of pressure as the tank hatch is opened by the worker for manual gauging or sampling operations," NIOSH officials wrote in the Friday posting.
Officials with the Occupational Safety and Health Administration say they're developing a national hazard alert for oil and gas workers who do the tasks with the greatest risk of such poisoning -- tank gauging, tank sampling and fluid transfer.
The vapors can disorient people to the point that they're unable to escape the lethal effect of the vapors. Many in the oil and gas industry know that hydrogen sulfide, or "sour gas," can kill an oil worker in seconds. Far fewer know that the volatile hydrocarbons can have the same effect -- a quick death.
Researchers last year found levels of butane at a tank hatch 48 times the level considered to be an "immediate danger to life and health" (IDLH), and butane was only one of several compounds in the sample (EnergyWire, Dec. 4, 2014). The sample, taken in November, had propane at five times the IDLH level.
In one of the cases documented by NIOSH, the worker's monitor showed that just before he died, he'd been exposed to an oxygen-deficient atmosphere and explosive levels of hydrocarbons. He'd been involved in a similar incident on the catwalk a few weeks earlier, when he was found disoriented and dizzy by another driver and was taken to the clinic for a checkup.
Three of the deaths occurred in North Dakota, three in Colorado, one in Texas, one in Oklahoma and one in Montana.
Public health researchers have indicated that the airborne chemicals that killed the workers also raise questions about whether the vapors pose a threat to people who live nearby. But they say there is little or no published research on the topic, and NIOSH researchers say their findings can be applied only to workplace hazards.
NIOSH has cataloged the details of the nine deaths in a database. The names of the workers were not listed in the posting, but some of the cases can be identified through OSHA records, autopsies and other records.
The first was Trent Vigus, who died at a well site near Lambert, Mont., in 2010. His cause of death was listed as heart problems. But some of the postmortem results contradict that and suggest Vigus' exposure to chemicals may have contributed to his death.
Laboratory tests turned up small amounts of propane and butane in Vigus' blood. Both these chemicals are found in crude from the Bakken Shale. Other oil and gas chemicals could have gone undetected, because the test was done for recreational drug use ("glue sniffing" or "huffing") rather than exposure to industrial chemicals.
In January 2012, Dustin Bergsing, 21, of Edgar, Mont., was found dead at a Bakken Shale well near Killdeer, N.D., where he was working as a flow tester. The cause of death was listed as "hydrocarbon poisoning due to inhalation of petroleum vapors." After determining that hydrogen sulfide was not a factor, OSHA officials said a citation of the employer for work-related exposure "could not be supported."
But in a lawsuit against the operator of the site, the lawyer for Bergsing's family took the sworn statement of a company official who said he was ignored when he warned his bosses that the company was allowing a dangerous buildup of lethal gases in the tanks.
In July 2013, truck driver Blaine Otto, 39, of Sidney, Mont., was found dead beside a tank hatch at a Bakken well site outside of Watford City, N.D. OSHA officials did not cite his employer but issued a "hazard warning letter" to the company saying employees should be given "four-gas meters" to warn them of dangerous vapors.
David Simpson, 57, died outside Ardmore, Okla., in March 2014, at a Woodford Shale well that produced oil and gas. He was found collapsed on a catwalk next to a tank hatch. Circumstances of his death are similar to other hydrocarbon inhalation deaths, but the Oklahoma Medical Examiner's Office listed his cause of death as unknown.
But in a Colorado death last year, the NIOSH data indicate that the medical examiner determined that the worker died of natural causes, based on toxicology and air monitoring by the employer.
The only death in which OSHA is known to have cited an employer in connection with VOC inhalation hazards occurred last year in North Dakota. Zachary Buckles, 20, a flowback operator working at a Bakken oil site across the Missouri River from Williston, N.D., died in late April. OSHA fined the company he worked for $2,800 for failing to train its workers in the hazards of petroleum vapors.
NIOSH officials said companies and workers can take precautions to prevent such deaths. The agency recommends the use of respirators, along with training in the hazards associated with measuring tank volumes and in the use of gas meters.
The simplest method outlined in the NIOSH posting is finding a way to measure what's in the tanks without resorting to the low-tech method of opening a hatch and essentially dropping in a rope.
But in many states, including North Dakota, the state requires some crude oil measurements to be done by hand.
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