Early Childhood Education
Childhood health problems such as asthma and other respiratory diseases, neurodevelopment disorders, endocrine disruption and cancers have all been associated with environmental risk factors. Air pollutants (both indoor and outdoor) lead, pesticides, tobacco smoke, and house dust mite and cockroach allergens are important environmental contributors to childhood illnesses. Genetic and socioeconomic conditions have been shown to increase the susceptibility of children to the adverse effects of these environmental stressors. Over the past several decades there has been growing evidence of the increase in incidence rates, morbidity, and mortality for a number of these health problems (Israel et al., 2005). In developing countries additional environmental burdens to children include exposure to biologically contaminated water, poor sanitation, disease vectors such as mosquitoes, and unsafe use of chemicals and waste all of which are worsened by the effects of poverty, conflict, and malnutrition. Over 40 percent of the global burden of disease attributed to environmental factors falls on children below five years of age, who account for only about 10 percent of the world’s population (WHO, 2006).
Children are more vulnerable than adults to environmental risks for the following several reasons (Landrigan et al., 2004; NAS, 1993; USEPA, 2006):
1. Children drink more water, eat more food, and breathe more air pound-for-pound than adults resulting in disproportionately heavier exposures to environmental agents.
2. Children’s metabolic pathways are immature making them in most cases less able to metabolize, detoxify, and excrete environmental agents.
3. Environmental chemicals can do more harm to central nervous, reproductive, immune, endocrine and digestive systems during phases of rapid growth and development, including embryonic, fetal and early childhood life stages.
4. Young children crawl, put things in their mouths, and sometimes even eat dirt. These actions tend to put them in closer contact with some environmental agents compared with adults.
5. Children have a longer life expectancy and more time to develop chronic diseases that might be triggered by early environmental exposures. Early childhood exposure to certain carcinogens or toxicants may be more likely to lead to disease than the same exposures experienced later in life.
Ambient and indoor air pollution is associated with asthma and other respiratory disorders in children. From 1990 to 2002 over 50 percent of children lived in counties in the United States where the ground-level ozone standard was exceeded during the year; from 2000 (first measured) to 2002, between 20 and 30 percent of children lived in counties where the fine particulate standard (PM2 5) was exceeded (USEPA, 2003). Ozone provokes airway inflammation and reactivity at low levels. Ozone levels have been related to increases in asthma emergency room visits in Atlanta, Georgia, New Jersey, and Mexico City. Fine particulates derived primarily from power plants and vehicle emissions have been associated with asthma and other respiratory conditions, low birth weight, and increased risk of birth defects (Landrigan, 2004).
Indoor air pollution consists of gases and aerosols from consumer products, allergens including dust mites, cat dander and cockroaches, pesticides, and gases and vapors from combustion sources. Environmental tobacco smoke is a common indoor pollutant associated with chronic respiratory infections and decrements in lung growth and development. In 1999-2000, 63 percent of white, non-Hispanic, 86 percent of black, non-Hispanic, and 49 percent of Mexican American children were exposed to detectable levels of blood cotinine, an indicator of tobacco smoke exposures (CDC, 2003).
Cockroach droppings or body parts play a significant role in asthma in many inner-city areas. In a study of seven U.S. metropolitan inner city areas skin test sensitization (an indicator of exposure) to cockroach was 69 percent overall and to dust mites was 62 percent. Cockroach allergens were highest in high-rise apartments, whereas dust mites allergen levels were highest in detached homes (Gruchalla et al., 2005). Other triggers of asthma include mold, animals, pollen, cold air, exercise, stress, and respiratory infections (NIEHS, 2006).
Chronic low-level exposure to lead measured in terms of blood lead levels is associated with cognitive deficits, developmental delays, behavioral problems, and diminished school performance at levels at least as low as 10 micrograms of lead per deciliter of blood (pg/dl) (CDC, 1991; WHO, 1995; USEPA, 2003). Pooled data from several studies around the world suggest the impact level may be as low as 7.5 pg/dl (Lanphear et al., 2005).
The elimination of leaded gasoline in many countries has reduced overall lead exposures, however studies of mining areas in Mexico indicate levels higher than five times the action limit of 10 ug/dl (CEC, 2006). In the United States lead- based paint in older homes is the primary source of childhood lead exposure. In developing countries, sources such as lead-oxide found in pottery glazes also represent a predominant exposure through food prepared and stored on the pottery.
Children are exposed to pesticides in soil, dust, and grass and through pesticide residues in food. Children of farm workers, pesticide applicators, and those living in agricultural areas are especially at risk. Key risks are cancer, birth defect, and damage to the nervous and endocrine systems (WHO, 2004). Organophosphate pesticides are used in the production of many foods consumed by children (USEPA, 2003). Between 1994 and 2000 the percentage of food samples in the United States with detectable levels of organophosphate pesticide residues ranged between 19 percent and 29 percent (CEC, 2006).
Childhood environmental health has become a focus of environmental research, agency initiatives, and public advocacy. Particularly in developing countries, environmental hazards and pollution are major contributors to childhood illnesses and disability. Further efforts are needed to better characterize the specific exposure mechanisms, developmental toxicity, and overall environmental risks associated with early childhood and to regulate these hazards in a manner protective of this vulnerable and precious life stage.
Further Readings: Israel, Barbara A., et al. (2005). Community-based participatory research: lessons learned from the centers for children’s environmental health and disease prevention research. Environmental Health Perspectives 113(10), 1463-1471; Landrigan, Philip J., Carole A. Kimmel, Adolfo Correa, and Brenda Eskenazai (2004). Children’s health and the environment: Public health and challenges for risk assessment. Environmental Health Perspectives 112(2), 257-265; Lanphear, Bruce P., Richard Hornung, Jane Khoury, Kimberly Yolton, Peter Baghurst, David C. Bellinger, Richard L. Canfield, Kim N. Dietrich, Robert Bornschein, Tom Greene, Stephen J. Rothenberg, Herbert L. Needleman, Lourdes Schnaas, Gail Wasserman, Joseph Graziano, and Russell Roberts (2005). Low-level environmental lead exposure and children’s intellectual function: An international pooled analysis. Environmental Health Perspectives 113(7), 894-899; Gruchalla, Rebecca, Jacqueline Pongracic, Marshall Plaut, Richard Evans III, Cynthia M. Visness, Michelle Walter, Ellen F. Crain, Meyer Kattan, Wayne J. Morgan, Susan Steinbach, et al. (2005). Inner city asthma study: relationship among sensitivity, allergen exposure and asthma morbidity. J. Allergy Clinical Immunology 115(3), 478-485; Centers for Disease Control and Prevention (CDC) and Commission for Environmental Cooperation (CEC) Publications and Web Sites: CDC (1991). Preventing lead poisoning in young children: A statement by the centers for disease control. Atlanta: Centers for Disease Control and Prevention; CDC (2003). National health and nutrition examination survey. National Center for Health Statistics. Atlanta: Centers for Disease Control and Prevention; CDC (2006). National Center for Environmental Health. Avaliable online at http://www.cdc.gov/nceh/; CEC (2006). Children’s health and the environment in North America: A first report on environmental indicators and measures. In collaboration with the governments of Canada, Mexico, and the United States. Montreal, Quebec. Available online at www.cec.org; National Academy of Sciences (NAS), National Institute of Environmental Health Sciences (NIEHS), and U.S. Environmental Protection Agency (USEPA) Publications and Web Sites: NAS (1993). Pesticides in the diets of infants and children. Washington, DC: National Academy Press; NIEHS (2006). Available online at http://www.niehs.nih.gov/oc/factsheets/ceh/home.htm; USEPA, Office of Children’s Health Protection (2006). Available online athttp://yosemite.epa.gov/ochp/ochpweb.nsf/homepage); World Health Organization (WHO) Publications and Web Sites: WHO (1995). Environmental Health Criteria 165-Inorganic Lead. Geneva: International Programme on Chemical Safety, World Health Organization; WHO (2004). Childhood pesticide poisoning: Information for advocacy and action. prepared for the United Nations Environment Programme. Chatelaine Switzerland: Chemicals Programme of the United Nations Environment Programme; WHO (2006). Children’s Environmental Health Program. Available online athttp://www.who.int/ceh/en/.