When a terrible odor blanketed the area around the Shell cracker plant earlier this month, residents had only their noses and sporadically high readings from public air monitors to assess the situation.
Many were left wondering what they were exposed to and whether it was dangerous.
On Tuesday, Shell officials held a virtual meeting to discuss the air monitoring results surrounding the event.
A senior toxicologist from the consulting contractor CTEH — the same company hired by Norfolk Southern in the wake of its derailment in East Palestine — told the community that it was safe.
The levels of benzene, a known carcinogen, detected at the fence line of the petrochemical plant in Beaver County were too low to “be associated with even transient discomfort or irritation,” said Christopher Kuhlman, the toxicologist that Shell hired to review air data and assess exposure.
“At these concentrations, if someone was standing at the fence line during this time,” he said, even for hours, they should not expect symptoms. He suggested that the bad smell could have been responsible for impacts that people around the area were reporting on social media and in calls to watchdog groups and local regulators.
“Strong odors can certainly cause headache, skin irritation, watery eyes,” he said.
Workers onsite who showed some of those symptoms reported they dissipated when they moved away from the smell, Mr. Kuhlman said.
Shell had set up a “restricted area” at the plant where readings of volatile organic compounds and benzene in particular were elevated, in order to protect workers.
On Tuesday, Shell’s General Manager Bill Watson said there were “no adverse affects to our employees or to you, members of the community.”
No workers were exposed to levels “above a Shell or OSHA standard,” he said, referring to the Occupational Safety and Health Administration.
Shell didn’t specify what its own standard is.
The OSHA standard for benzene exposure is no more than one part per million over an eight-hour period (a typical workday) and up to 2.5 parts per million during a short stint (less than 15 minutes of exposure).
All of Shell’s air-monitoring data showed benzene levels in the parts per billion count, which is a thousand times less than parts per million. The highest reading was 58 parts per billion over 30 minutes on April 11.
Anthony Pizon, chief of medical toxicology at the University of Pittsburgh Medical Center’s Department of Emergency Medicine, who reviewed the air monitoring data on Monday, said the numbers were too low to raise concerns about public health.
“You can smell something and it can be irritating,” he said, without it being harmful.
Still, Dr. Pizon cautioned that looking at air-monitoring data to glean community impacts isn’t a straight line.
“From my vantage point, it’s hard to go off those numbers,” he said. “I would look at the patients themselves.”
He encouraged anyone who thinks they were exposed to anything toxic to call the poison control center at 800-222-1222.
Dr. Pizon said a few calls related to the event did come in, with “minor, irritant complaints.”
Benzene, in particular, is presumed to have cumulative health impacts at ambient levels — as you would see in community exposure, said Tee Guidotti, a retired professor of occupational and environmental medicine at George Washington University who now works as a consultant.
“With occupational levels, there’s some evidence that suggests peak levels are the bad actor,” he said.
Mr. Guidotti explained that worker exposure limits are set much higher than those for the general population, in part because workers are presumed to be healthier than the most vulnerable community members. He also said that over the years, health impacts have been detected with increasingly lower levels of benzene exposure.
The source of the smell
Shell officials pinpointed the source of the smell to its wastewater treatment plant, which was processing excess hydrocarbons.
One of the first facilities to be commissioned at the chemical complex in April 2021, the wastewater plant is responsible for treating all the process water, stormwater and cleaning water before it is discharged into the Ohio River.
The wastewater first gets dumped into tanks where oil is skimmed from the top. It then goes into the biotreaters where bacteria break up and eat the remaining hydrocarbons. After passing through additional sand filters, the water is released.
The problem on April 11 was caused by a low level in those tanks, which prevented oil from being skimmed off the top. That meant more hydrocarbons got dumped into the biotreaters.
The wastewater treatment plant has had malodor events several times before, including earlier this year.
On April 17, the Department of Environmental Protection issued a violation notice to Shell for malodors from its wastewater treatment plant between Jan. 25 and Feb. 16, caused by hydrocarbons flowing into the biotreaters through a valve that had been left open.
Between October and December, odors wafted from the wastewater treatment plant, traced back to excess hydrocarbons in the process water coming from the ethane cracking unit. Shell estimated that it released two tons of benzene from this episode. Its permit allows it to release up to 11 tons of benzene over a 12-month rolling period.
Total emissions from the April 11 event aren’t yet available.
The Shell plant is currently shut down to repair the shield around one of the ground flares, which had developed a hot spot and had to be continuously sprayed with a water hose to cool the problem area and keep it from spreading.
Shell officials didn’t have a restart date but said they would post about it on Facebook in advance, since it will involve increased flaring.
Mr. Watson said the company has taken measures to relieve the smell issues at the wastewater plant and is also evaluating longer-term measures.
He apologized for the event and conceded that the company should communicate with the community faster when a problem is detected. Until Tuesday, the only notification from Shell was an April 12 Facebook post acknowledging the odor.
“To be clear Shell NEVER posted on facebook that they were releasing benzene,” the community watchdog group Eyes on Shell tweeted during the virtual meeting.
Clifford Lau, a chemist who volunteers with the group, said earlier in the day that he assumed Shell would notify the public if it knew benzene was being released. Mr. Lau also wondered what other chemicals were causing the high counts of volatile organic compounds that were being detected. Benzene is just one of many components in that group.
“What people want to know is, ‘Do I need to know something to protect myself if I’m compromised,’” he said. “And that is not being fulfilled.”
Anya Litvak: alitvak@post-gazette.com
First Published: April 26, 2023, 9:30 a.m.
Updated: April 26, 2023, 4:01 p.m.
