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5 questions: Your exposure to cancer risk factors in Philly could be killing you

Eastwick, surrounded by Philadelphia International Airport, highways and industry, is part of the exposure study.
Eastwick, surrounded by Philadelphia International Airport, highways and industry, is part of the exposure study.Read moreMARY LEONARD / U. of Pennsylvania

The residents of Eastwick face many environmental challenges.  Nearby are the Philadelphia International Airport, I-95, a landfill, refinery and other industrial sites.

Likewise, the residents of Chester have numerous industrial sites, plus heavy traffic.

The associated pollution makes up a portion of the residents' exposome, a term that refers to all the exposures an individual – or a community – has over a lifetime. How those exposures relate to health is the next big question.

University of Pennsylvania researcher Marilyn Howarth, director of the Community Outreach and Engagement Core for Penn's Center of Excellence in Environmental Toxicology, and an adjunct associate professor of emergency medicine and pharmacology,  has been working with these communities to determine their exposomes and help them figure out what to do about it. She spoke to us recently about her work.

Tell us more about the exposome.

I have for a long time believed that the current method of looking at risk to people's health has been too one-directional, too focused on one chemical at a time. Our lives are filled with exposures every day – not necessarily terrible exposures, but actual exposures. We eat things. We drink  water. We sometimes come into contact with chemicals in our workplaces or hobbies. By looking at any single chemical, we don't do justice to the concept of risk and helping people understand what their risk of illness or disease might be from the combined effects of all exposures.

We've been involved now in Chester and Eastwick for a long time. What we were hoping to do was bring together all the exposures in those communities to form a context.  If your only exposure is to a particular chemical in the soil that might be left over from a hazardous waste site, in and of itself, it might not pose a very big risk to you for cancer or some other health effect. But say you are being exposed at the same time to air pollution from a nearby highway, and you're also close to refineries that have emissions, even if those emissions are lower than allowed by their permit. Adding all these together, the opportunity for these exposures to cause you harm increases.  The varied exposures  might be working on the same body parts and the same mechanisms of causing disease. That cumulative exposure might mean you're more likely to get the disease than if you're exposed to any one toxic chemical singly.

How does this play out in Eastwick?

They are overburdened by the sum total of chemicals they are exposed to.  One of the major concerns  is polyaromatic hydrocarbon — PAH — which is from combustion sources and from oil that hasn't been combusted.  PAH is a large class of chemicals, and quite a few of them are carcinogenic.  But when the U.S.  Environmental Protection Agency calculates what would be a safe level of PAH exposure, they are not considering all the other exposures that people have.

Eastwick also has air pollution from all the highways, the refinery and the airport. Our region in general is out of compliance for one of those pollutants in particular, ozone. It's never been in compliance with the EPA standards.  Even these are set with health in mind, but they are not set to be absolutely protective of health. As a member of the public, I'd like to think that the air quality standards were set at a place where there would be no additional asthma attacks or heart attacks. But cost-benefit is considered. There are very good data to show that if the standards were lowered further, it would save thousands more asthma attacks and  heart attacks. I don't think people know that, and I think they should.

What about Chester?

For decades, Chester has been the place where new industry has opened up shop. In the 1990s, a community group, the Chester Residents Concerned for Quality Living, took the state Department of Environmental Protection to court and said: "Enough is enough. When are you going to stop giving out permits to have more polluting sources in our community?"  That suit went all the way to the Supreme Court. The company asking for the permit later withdrew the application, so the court did not rule on the case.

But it describes what I'm  trying to do on the Chester Environmental Partnership, which is to push regulators to be thinking about the community exposome when they give permits.  If the DEP does not consider all of the multiple pollution exposures to the people of Chester when setting permit standards for emissions, then they  are not protecting the health of the community,which is their mission.

What are you specifically trying to do in each of these communities

We are trying to identify opportunities to reduce risk by knowing first what all the exposures are.  We're looking for strategies, both regulatory and behavioral. We're hoping that we can impress upon regulators the importance of taking a more cumulative impacts approach to their permitting. We're working with the communities to have them gain more insight into a variety of tactics. Maybe they can change some zoning. Maybe they can work toward decreasing traffic from older diesel trucks, which pollute more.  We are working with medical providers to encourage them to counsel patients about how to avoid exposures.

We think that if more people know that air quality has a direct impact on their health — their asthma and other serious health problems — we can help them decrease outdoor activity on days that are poor air quality days, which will decrease health effects.   People can sign up for Air Quality Alerts at

On a broader level, what do you think should be happening?

The key points really are that people at all levels — people who live in communities, medical providers who take care of them, and regulators who make determinations about what can be allowed in these communities — should work together to look at data that can reflect how overburdened people are. The EPA has collective information about the sum total of permits they have given out. They really should be able to look at the kinds of things that are being put into the area and decide scientifically, what is enough? More research would really  help — the science of how much worse cumulative exposures are, compared with single exposures.

I'm optimistic that as we develop more science around cumulative impacts, the interest in looking at cumulative exposures will increase, and that's when environmental justice communities like Eastwick and Chester will see improvement. I just don't know how soon that will be, but I think it will happen.