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Linda Sheldon, Division Director:
The Human Exposure and Atmospheric Sciences Division conducts research to support EPA's mission to protect human health and the environment. Specifically, we conduct research to understand the movement of chemicals from their sources to contact with humans, or human exposure. Within the division, we develop methods, measurement data, and models to understand the movement of pollutants from their sources, through environmental concentration, to contact with humans and ultimately into the body, to a target tissue dose.
Human exposure research is critical to the division's mission. It's important for us to understand why and how people come into contact with chemicals in order to develop effective regulatory policies.
In order to understand human exposure, you need to know two things: first, what are the concentrations of chemicals in the environment, and second, what are those activities that bring people into contact with those chemicals.
The scientists in our division are going to take you on an exciting tour of our human exposure research program. So sit back and enjoy this exciting research.
Hi, I am Ron Williams, an exposure measurements scientist here in the NERL.
One of our is collecting information that helps the US EPA develop sound scientific foundations for the regulations that protects the health of Americans from harmful environmental exposures. Questions we must answer include: what are people exposed to in the air they breath? What are the sources of their exposures and how does human activities and environmental factors influence various human subpopulations.
This can be very difficult work and requires a multitude of talents. We do this using teams built around the talents of exposure scientists, physical scientists, statisticians, modelers, and data specialists. Our instrumental and laboratory capabilities enable us to detect and analyze environmental pollutants at very low concentrations.
How do we accomplish our mission? We identify human populations needing an original or refined exposure assessment for airborne pollutants. We go to where these groups live and investigate how they live their lives. Second, it involves developing the data collection tools needed to better define human exposures. This may require the development of novel, low burden passive monitors, survey instrument that collect time and activity information, or sophisticated source apportionment and statistical analysis procedures. Lastly, we perform field studies by developing the necessary human subjects safety protocols, the information collection requests and peer-reviewed study designs that ensures the NERL's research will be useful to the Agency and accepted by the scientific community at large.
The Detroit Exposure and Aerosol Research Study (the DEARS) is just one example of the work we are doing. In the DEARS we are collecting nearly 1200 days of data involving the collection of personal exposures, residential indoor, residential outdoor, and community-based monitoring.
This represents a unique situation where the NERL can develop the tools and approaches to help communities and regions better understand the usefulness of using data from central community monitors (such as state & local air sites) to assess human health risk. By being able to collect data where individuals live, understand where they go and what they do, and to be able to determine the impact of various air pollution sources as people live their lives, we have a unique ability to put together the pieces of the exposure puzzle like no other.
Ever wonder where the air you breathe comes from? Talk to us. We are the National Exposure Research Laboratory. That's our job.
The goal of our research program is to understand what chemicals people come in contact with, at what levels, what the sources of these chemicals are, and where, when, how often, and why they come into contact with those chemicals in their everyday environment. To do this, we study the locations where people spend significant amounts of time, and for children, this includes their homes, daycare centers, or schools.
We collected a dust sample using a wetted wipe and we collect it from different locations on the floor, on surfaces and toys, and any other locations that the child may come in contact with. Or we would use the HSVE3 to collect the dust sample, or in some instances, we would actually collect the dust sample by asking the care-giver to provide us with a vacuum cleaner bag.
In addition to the environmental samples that we collect while in the home, we also collect personal samples. The personal samples include a cotton garment so we can estimate the amount of chemical and dust that ends up on the child's skin during normal play behavior. We also collect a duplicate diet plate. This allows us to estimate the amount of chemicals that a child may ingest from eating the food a child eats during the day. The last sample we collect is form the child himself - we collect a urine sample.
And of course, we need to know what the child has been doing during the time that we're collecting these samples and we collect this information in a time activity diary. We use all of this information to provide data to support our clients, to fill existing data gaps for exposure and risk assessment for children, identify new and emerging chemicals of interest, refine our methods, provide inputs to the exposure and dose models, and develop future research directions for new and emerging exposure issues.
The Division's methods and measurement research is used to develop data on human exposure. This data is then put into models so we can predict both exposure and does of humans to chemical contaminants. These tools are used to improve exposure estimates and in turn are used to make important environmental regulatory decisions.
In HEASD's Exposure Modeling Research Branch, we develop, evaluate, and apply the SHEDS human exposure models.
These models combine measurements of pollutant concentrations with human activity pattern data and census demographics to simulate exposures for a population of interest.
When that population is an urban metropolitan area or a community within it, available air pollutant monitoring data may not adequately characterize the spatial and temporal trends in concentrations across the area.
Air quality models can be used to improve our estimates of exposures by providing estimates of air pollutant concentrations continuously in time across the entire area.
In collaboration with the modelers in the Atmospheric Modeling Division, we have been able to integrate air quality and exposure models in a number of applications to provide improved estimates of air pollutant exposures, and better understand the impact of different air quality modeling approaches on exposure estimates.
Mike Tornero, a.k.a. Rogelio Tornero-Velez:
Here in HEASD, we develop methods and approaches to characterize exposure in the population. We develop fate and transport models to understand the processes that lead to exposure. But what happens once that chemical is inhaled or ingested?
Well, we use dose modeling to understand the processes that lead to target tissue dose.
Dose models can also help us interpret exposure information. Here, we can relate urinary metabolites to different types of pathways. Hand to mouth pathways to urinary metabolites or dermal exposure pathways to urinary metabolites. Here, we see that hand-to-mouth is a better explanor of urinary metabolites than dermal exposure.
In summary, dose modeling can help us better interpret exposure, and they can provide better information for risk assessment.
See that road over there? You may not know it but that road could be bad for your health. The cars and trucks that we drive emit air pollution that, when breathed, can cause health problems. Roads that carry as few as 10,000 vehicles per day are associated with respiratory symptoms and there are over 150,000 miles of these types of roads in the U.S. More than 35 million people in the U.S. live close to a roadwayâ€¦From stop and go traffic on congested streets, to busy interstate highways, we're exposure to traffic related air pollution that affects our quality of life.
In Human Exposure and Atmospheric Sciences Division, we conduct research to determine the levels and types of traffic-related air pollution that people are exposed to everyday. This information is useful in better understanding the implications of living, going to school or working near a roadway and can be used to develop guidance and recommendations for communities that are impacted by traffic -- guidance that can help reduce exposure to traffic-related air pollutants and as a result, improve public health.
In these studies, we're measuring air pollutants that are emitted on roadways and their movements into residential areas to determine the extent to which pollutants from traffic impacts communities.
By collection this important information we can develop and apply computer models that allow us to characterize the air pollution that people breathe from emissions to exposure.
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