Diesel Exposure and Traffic-Related Air Pollution
CDC’s Environmental Hazards and Health Effects Program (EHHE) is continuing an investigation of the effects of diesel exposure and traffic-related air pollution on asthmatic children in Ciudad Juarez, Chihuahua. This investigation is important because heavy-vehicular traffic must pass through densely populated city areas in Ciudad Juarez prior to reaching the border crossing bridges and because most of heavy-vehicular and transportation traffic is powered by diesel engines.
In 2003, EHHE conducted a study of 200 indigent children (100 who have asthma and 100 controls) aged 6 to 12 years. Participants selected from schools with varying distances from the major roads were followed for 8 consecutive weeks. EHHE simultaneously monitored traffic-related air pollutants including PM2.5 (particulates with ≤ 2.5µm of aerodynamic diameter), nitrogen dioxide (NO2), and elemental carbon in PM2.5. EHHE evaluated the health effects from the exposure to these pollutants using airway inflammation tests, pulmonary function tests, and a symptoms questionnaire. Preliminary results suggest that the closer the schools are to major traffic roads the higher the occurrence of airway inflammation and respiratory symptoms such as asthma.
EHHE is currently developing "proximity to major traffic roads" as an environmental indicator by characterizing the air pollution exposure in relation to the distance from major roads using Geographical Information Systems (GIS). EHHE will also link the GIS exposure data to health effects in at-risk populations, such as children who have asthma. Results from this study will characterize exposure to traffic-related air pollution in Ciudad Juarez and will examine associations between this exposure and several health outcomes in populations susceptible to respiratory problems.
This information will have a direct impact on public and environmental health, by giving policy makers the necessary scientific evidence to change traffic regulations. For example, the data may lead to reducing heavy vehicular traffic flows in certain areas during school hours. Furthermore, this study will serve as the basis to develop similar models that use data from established environmental monitors and could improve our understanding of pollutant distribution within the city and the extent of population exposure. Other cities facing similar pollution problems may find this model helpful.
Pesticide Exposure in Women & Children
In 2001, EHHE conducted a pesticide exposure study of reproductive-age women in the California-Baja California region. This cross-sectional study measured pesticide metabolite levels in 100 women of reproductive age who live in communities where they may regularly be exposed to pesticides. Data were collected by questionnaires and single urine samples. Urine samples were analyzed for organophosphates (non-specific and specific metabolites), organochlorines, carbamates, herbicides, insect repellent, disinfectants, and pyrethroids. Levels of metabolites measured in urine showed recent exposure to organophosphate and chlorinated phenolic pesticides, but levels were so low that health effects are not expected.
EHHE also completed an investigation of pesticide exposure of children in Yuma County, Arizona. This cross-sectional study was done to determine whether children who live or go to school close to agricultural fields had higher urine levels of pesticides than did children who live or go to school farther away from agricultural fields. Urine samples from children and dust samples from their households and schools were collected from October 1999 to February 2000. A total of 152 households and 6 schools participated. Urine samples were tested for organophosphate pesticide metabolites and dust samples were tested for 43 specific pesticides. Both the level of pesticide metabolites in urine and the level of pesticides in dust were low. Results showed that distance from household or school to agricultural fields was not significantly associated with exposure to pesticides.
Other EHHE Activities
EHHE has:
- Conducted two binational pediatric lead assessments in Arizona-Sonora and New Mexico-Chihuahua using portable blood-lead analyzing technology.
- Conducted a retrospective study on the association between pediatric asthma and ambient air quality in the Paso del Norte airshed in the El Paso, Texas, area.
Results of these activities are being prepared for publication.
