Childhood Asthma and Environmental Risk Factors in the City of Buffalo, New York
Information Sheet - January 2005
The New York State Department of Health's (NYSDOH) Center for Environmental Health conducted a study that investigated the relationship between environmental risk factors and asthma. This study was funded by a grant from the Agency for Toxic Substances and Disease Registry (ATSDR) with staff support from NYSDOH.
The project's main objective was to find out whether children with possible residential exposure to urban air toxics had a higher risk of having asthma. The study also looked at the relationship between childhood asthma and exposures to chemicals in indoor and outdoor air, and other risk factors for asthma. These risk factors included a family history of asthma and medical care access. Study participants were children aged 1 through 17 years living in the City of Buffalo, New York, during 1996 and 1997. Urban air toxics (UATs) include 189 chemicals listed in the 1990 Clean Air Act Amendment because they are pollutants that are hazardous to human health. The U.S. Environmental Protection Agency (EPA) considers air as the principal route that UATs enter the environment. In urban areas, UATs can be released from active industrial facilities and hazardous waste sites.
Researchers used several methods to identify and recruit families for participation. A commercial mailing list with the addresses of families with children living in Buffalo was obtained. Since this list probably did not represent low-income and minority groups, four public schools and two private schools with high minority enrollment were asked to participate in the study and NYSDOH used outreach activities to find additional study volunteers in the community. Each family was sent or given a two-part questionnaire. The first part included questions about parents' education, family income, household smokers, household pets, number of rooms in the house, type of medical care used by the family, and family members with asthma. The second part asked whether the oldest child had been diagnosed with asthma or had asthma symptoms. This also included questions about the severity of the child's asthma symptoms, asthma triggers, medical treatment, and family asthma history. A child was classified as an asthma case if any two of the following seven conditions were reported: 1) a physician stated that the child has asthma, 2) the child still had asthma at the time of the study, 3) the child had whistling or wheezing on most days or nights in the past year, 4) the child had ever experienced wheezing, 5) the child had a dry cough at night in the past year, 6) the child had exercise-related attacks of wheezing in the past year, or 7) the child had ever visited an emergency room or hospital for asthma. A child with none or one of these conditions was classified as a control.
Lung function and allergy skin tests were conducted on 202 children (88 asthma cases and 114 controls). NYSDOH staff also visited 99 homes of these children to collect dust and air samples. These samples were used to measure the levels of certain allergens (substances that can cause allergic reactions), molds, metals, a group of chemicals called aldehydes, and acetone, a solvent.
Two possible sources of UATs are active industrial facilities listed in the Toxic Release Inventory (called TRI sites) and inactive hazardous waste sites. Researchers estimated ambient air levels of UAT from TRI sites in the homes of the participants using an air-dispersion model developed by EPA. In addition, 17 inactive hazardous waste sites were evaluated to determine if residents living near the sites could have been exposed to pollutants, including metals, volatile organic compounds, and pesticides. Researchers reviewed the site histories, studied air and soil from the sites, and evaluated human activity at the sites. An area of contamination was drawn around nine sites that constituted a potential for exposure to residents living within an area of contamination. Participants were grouped into those inside and outside an area of contamination.
Asthma prevalence for this study is the percentage of children classified as asthma cases. To determine if a group of children with a particular characteristic or exposure had a higher risk of having asthma, researchers compared the percentage with asthma in a particular group (for example, boys) to the percentage in the other group (for example, girls). This comparison was done for different demographic characteristics of the children, characteristics of the indoor and outdoor home environment, and possible exposure to pollutants from TRI and hazardous waste sites. To see how important all of these variables are in combination, researchers used a statistical technique called logistic regression. If a characteristic or exposure was related to having childhood asthma in a statistical sense, that group had an increased risk of having asthma.
There were 3,008 children who were eligible to participate in the study. Fifty percent were boys, 17% were aged one through four years, 73% were White, 22% were African American, and 8% were of Hispanic origin. Twenty-three percent were living below the poverty level. Children classified as asthma cases numbered 770, making the prevalence of childhood asthma 26%.
The following participants had a significantly increased risk of having asthma: boys, older children, African Americans, Hispanics, those having a family member with asthma, and those whose parents reported that they had no time to seek medical care. Information relating to the indoor and outdoor home environment indicated that the risk of childhood asthma was significantly higher among children whose parents reported that one or both parents smoked, a home humidifier or vaporizer was used, there was dampness in the home, a chemical odor was present indoors, and frequent truck traffic was present in the neighborhood. When researchers took these personal and home environmental characteristics into account, there was also a significantly increased risk of having asthma among children who lived in a residence with a potentially increased concentration of ammonia from a TRI site.
The results from the allergy skin testing or the air and dust sampling suggested that children living in homes with increased levels of benzaldehyde (one type of aldehyde), cat allergen in the living room rug, or cat allergen in the child's mattress had a higher risk of having asthma.
After researchers accounted for other characteristics and indoor and outdoor environmental factors, the study found that a potentially increased ambient air level of ammonia from industrial facilities might be associated with an increased risk of childhood asthma. Also related to childhood asthma were environmental residential factors (such as frequent truck traffic in the neighborhood, chemical odors indoors, parental smoking, and humidifier or vaporizer use), several socioeconomic factors, having a family member with asthma, and having limited access to medical care. The results demonstrated that indoor and outdoor environmental factors play important roles in increasing the risk of having asthma. The study confirms the complicated nature of asthma. However, minimizing asthma may be possible by reducing certain environmental exposures in and around the home.
If you have any questions or would like more information about this study, please contact:Marta Gomez, MS
NYS Department of Health
Center for Environmental Health
Bureau of Environmental & Occupational Epidemiology