December 11, 1996

Media Contacts: Sarah Goodwin, 404/727-3366 - sgoodwi@emory.edu
Kathi Ovnic, 404/727-9371 - covnic@emory.edu

Say you're a bicycle-riding, barbecue-loving house painter who lives in the suburbs, gardens on the weekends and eats cheerios for breakfast. Are you at more or less risk of exposure to harmful pollutants than a subway-riding vegetarian who lives in the city, drinks eight glasses of tap water a day and whose hobby is making stained glass. And is either of you at more risk in the winter or in the summer?

Scientists already know quite a lot about environmental pollutants, including pesticides, metals, and atmospheric chemicals and how they are harmful to humans. What they don't really know, says Emory University Rollins School of Public Health professor Barry Ryan, is exactly how much we are exposed to pollutants in our daily lives, and how variations in diets, kinds of houses, soil, air, hobbies, daily routines, and even seasons of the year influence that exposure.

Ryan is directing one aspect of an Environmental Protection Agency (EPA)-sponsored study on human exposure assessment that is aiming at the nitty-gritty of pollution effects.

"We are quite familiar with what comes out of smokestacks or what might be dumped into hazardous waste sites," he notes. "And, in the clinical sense, we know many things about the effects of environmental pollutants, for example, that if children receive excess lead doses they have cognitive deficits. This project is addressing a missing link in our understanding of the effect of pollutants on populations -- in other words, exactly what we are exposed to in our daily lives."

The study is a collaborative effort among the EPA, Emory, Harvard University, Rutgers University, the University of Arizona, Johns Hopkins University and private research laboratories. In two of the three study sites researchers gathered data from large populations in the upper Great Lakes region around Chicago and the State of Arizona, with the goal of determining the feasibility of monitoring for multiple exposures.

Ryan's group is charged with monitoring a relatively small group of individuals (approximately 60), repeatedly over the course of a year to evaluate the "temporal variability" of the exposures.

"Typical exposure assessment studies are done on individuals for a very short period of time, and only once," says Ryan. "Our participants were monitored every eight weeks for a year, during six complete cycles."

The investigators studied exposure to 15 different pollutants, including heavy metals (lead, cadmium, chromium, and arsenic); pesticides (chlordane and DDT derivatives); and polynuclear aromatic hydrocarbons (PAHs), which are bi-products of combustion from automobiles, airplanes, or cooking). During each one-week cycle all the likely changes in activity, food intake and external sources of pollution were monitored through sampling indoor air, outdoor air, house dust, drinking water, soil, skin and blood and urine. Only one person per household was monitored. Participants carried a personal monitor to measure additional exposures outside of the home.

The subjects were asked to provide an exact duplicate diet of their food intake during four days of each cycle, just as if a hungry ghost researcher were sitting at the dinner table.

"If they ate a bowl of cereal, we wanted a bowl of cereal. If they ate a plate of spaghetti, we wanted a plate of spaghetti," explains Ryan. The duplicate meals were placed in special containers and later pureed into a mush that could be analyzed for pollutants.

Four levels of questionnaires covered demographic characteristics, daily activities, hobbies or occupations, housing conditions, prescription drug use, pesticide use, time-activity profiles and a dietary checklist.

The investigators wanted to know if people tended a fire, used tobacco products, took a shower, painted a room, traveled on roadways, lay or sat on a carpet, worked in an enclosed garage, opened their windows, exercised vigorously, or had special hobbies. Stained glass work might elevate levels of lead, for example, or gardening might raise exposure to pesticides.

Ryan believes having data from different seasons will prove to be significant. Exposure to pollutants at different times of year might vary more than you think, he explains.

"For example, many people eat substantially different foods in the winter than in the summer. You might barbecue in the backyard in the summer. In the winter, your vegetables and fruits might come from different places and be exposed to different pesticides. And most people spend more time outdoors in the summer."

Analysis of all the data will take many forms over the next several years. The pilot study might eventually lead to a large national investigation, says Ryan, where it would be necessary to monitor approximately 10,000 subjects for up to 20 years.

Meanwhile, Ryan and his co-investigators are digging into their data, comparing biological to environmental samples, activities to exposures, and seasons to specific pollutants. With 4,000 environmental samples, 450 each of four questionnaires and two checklists, four metals, six pesticides, and five polynuclear aromatic hydrocardons, he estimates they have between 50,000 and 60,000 concentration-time-person-specific items to keep them busy for awhile.

For more general information on The Robert W. Woodruff Health Sciences Center, call Health Sciences News and Information at 404-727-5686, or send e-mail to hsnews@emory.edu.

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