EPA, Emory monitor daily and
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 more or less at 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?
seasonal pollutants exposure
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, said 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
"We are quite familiar with what comes out of smokestacks or what might
be dumped into hazardous waste sites," Ryan said. "And, in the
clinical sense, we know many things about the effects of environmental pollutants.
For example, if children receive excess lead doses they have cognitive deficits.
This project is addressing a missing link in our understanding about 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 in 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 about
60 individuals 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," said 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, which are byproducts
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, blood and urine. Only one person per household
was monitored. Participants carried a personal monitor to measure additional
exposures outside 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," explained
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, laid 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 said.
"For example, many people eat substantially different foods in the
winter than in the summer. You might barbecue in the back yard 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,
said 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 samples 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 hydrocarbons, he estimates they have between 50,000
and 60,000 specific items to keep them busy for a while.
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