Aromatics are a base component of gasoline derived from crude oil. Refiners manipulate these substances – mainly mixtures of chemicals like benzene, toluene, and xylene – to increase the octane rating, a measure of how well the fuel actually works.
Lead served this purpose in gasoline until 1995, when the Environmental Protection Agency banned the component because it is highly toxic and harmful to human health. Aromatics were the answer to make up for the drop in octane ratings. But 20 years later, some in the environmental and health communities are saying that aromatics are no better.
“Aromatics in gasoline are the new lead,” said Carol Werner, executive director of the Environmental and Energy Study Institute, a Washington-based group that advances policy solutions for clean and sustainable energy.
“It’s what keeps me up at night,” Jessie Stolark, a policy associate at EESI, said in the joint interview.
They, along with other members of the scientific community, are concerned that aromatics exist in the environment at unsafe levels. The chemicals get released into the air as nano-sized particles – ultrafine particulate matter, or UFPs – that can be absorbed through the lungs or skin. Studies in peer-reviewed journals like the Journal of Environmental Science and Health, Environmental Health Perspectives and Particle and Environmental Toxicology, have linked these particles from aromatics to diseases ranging from ADHD to asthma.
Werner says a growing body of health literature supports a correlation between aromatic use and health problems. But skeptics say more research is needed to build a consensus.
Aromatics in gasoline are the new lead. – Carol Werner, Environmental and Energy Study Institute
But when asked yesterday, Brugge said the past year’s evidence has been significant.
“The evidence has grown in favor of UFPs being a health risk, but it’s not yet enough to drive federal policy,” he said, adding that more studies are forthcoming.
The Energy Future Coalition says the evidence is already there. The Washington-based group that advocates for clean and new sources of energy points to more than 100 studies addressing the link between motor vehicle emissions and health effects.
Heather Volk, a medical professor at the University of Southern California, said in an interview that “when it comes to respiratory and cardiovascular systems, those effects are pretty well established.” She said it’s more difficult to verify a link between the cognitive and genetic disorders.
The general scientific community agrees that benzene, a known carcinogen, is the most hazardous. But according to Steve VanderGriend, a director at the Wichita, Kansas-based Urban Air Initiative, all aromatics eventually take the form of benzene.
VanderGriend said the two other aromatics – toulene and xylene – convert to benzene during the combustion process, making them equally harmful.
The Urban Air Initiative works to publicize the health threats of gasoline emissions.
In 2007, EPA capped the volume of benzene that could be used in gasoline due to its known health effects. But it chose not to regulate any other aromatics.
“Regardless of specific regulatory action to control aromatics, the increased use of ethanol… will contribute to lower aromatics levels,” EPA said in its final 2007 rule.
The agency’s reasoning at the time was that the Renewable Fuel Standard would push refiners toward using more ethanol, which would dilute the aromatic content.
But while benzene was capped and ethanol use has skyrocketed, the use of aromatics in gasoline has not declined much. Aromatics represent roughly 25 percent of the average gallon of unleaded gasoline, according to a Morning Consult review of components that make up gasoline sold by five major oil and gas companies.
EPA is “not managing any type of regulatory control over” aromatics, VanderGreind said.
The agency responded by saying in a statement that it “is setting more stringent standards designed to eliminate fuel vapor-related evaporative emissions and improve durability. The evaporative emissions program represents about a 50 percent reduction from current standards and applies to all light-duty and onroad gasoline-powered heavy-duty vehicles.”
EPA also said that the aromatic content of gasoline has fallen 20 percent since 2006, “more than twice what one would expect based just on dilution with 10% ethanol.”
The oil industry sees aromatics as a non-issue.
“Current EPA limits are protective of public health,” said Carlton Carroll, a spokesman who works on fuels issues at the Washington-based American Petroleum Institute. “Lowering aromatic content would require further processing of crude oil.”
That would increase capital and operating costs at refineries, thereby also increasing greenhouse gas emissions, Carlton said.
The menu of policy items available to deal with the issue is slim and divisive. The Urban Air Initiative would like to see more ethanol in fuels to boost octane ratings in place of aromatics. The Renewable Fuels Association says ethanol reduces tailpipe emissions by up to 50 percent, a statistic supported by a 2012 study from engineers at Ford Motor Company.
But with bipartisan bills in Congress that would eliminate the Renewable Fuel Standard’s ethanol-blending requirement, increasing fuel-ethanol volumes is seen as a heavy political lift, if not impossible.
EPA has mandated that diesel engines use an updated technology that is designed to stop particulates from getting into the air. But doing the same for light-duty vehicles is tricky and more expensive, according to environmental groups.
Regardless of that challenge, if the scientific community reaches a consensus on aromatics, EPA could move to scale back or eliminate them as they did with lead.
“It is a relatively new issue,” Werner said. “What’s important is for the public health community and EPA to become aware that this needs to be addressed.”
Update: This article was updated to include comments from EPA.