Paul Anastas Ph.D. Assistant Administrator for Research and Development and Science Advisor U.S. Environmental Protection Agency (EPA)
Linda Birnbaum, Ph.D., D.A.B.T., A.T.S. Director, National Institute of Environmental and Health Sciences and National Toxicology Program National Institutes of Health, United States Department of Health and Human Services
Children’s environmental health -- the study and prevention of disease and disabilities in children from exposures to social, physical, biologic, and chemical agents -- has emerged as a new field of research, policy, and clinical practice (Landrigan et al. 1998). The growth of this field has been fueled by the emergence of new morbidities in children, research showing that the fetus and child are particularly vulnerable to environmental influences, and mounting evidence implicating environmental exposures as major risk factors for prevalent diseases and disabilities in children (Lanphear, 2005).
One in six American children have a developmental problem, from a subtle learning disability to overt behavioral disorders, such as attention deficit hyperactivity disorder (ADHD) or autism (Boyle et al. 1994; Hertz-Picciotto, 2009). These conditions can severely impair a child’s ability to succeed in school, elevate their risk for violent and criminal behaviors, and dramatically diminish their ability to contribute to society. The findings from some of the most thoroughly studied and widely dispersed environmental toxicants indicate that exposure to exceedingly low levels are risk factors for the “new morbidities” of childhood -- intellectual impairments, behavioral problems, asthma and preterm birth (Lanphear, 2005). Indeed, there is often no apparent threshold and, in some cases the effects appear to be greater at the lowest levels of exposure (England et al. 2001; Canfield et al. 2003; Lanphear et al. 2005; Yolton et al. 2005).
Exposures to established environmental toxicants -- such as lead, tobacco, PCBs and mercury -- have consistently been linked with higher rates of intellectual impairment or behavioral problems, such as conduct disorder and ADHD (Needleman et al. 1990; Schantz et al. 2003; Kahn et al. 2003; Wakschlag et al. 2002; Stewart et al. 2003; Needleman et al. 1979; Lanphear et al. 2005; Yolton et al. 2005). There is emerging evidence that a whole host of new environmental chemicals – such as Bisphenol A, PBDEs, pesticides, phthalates, and airborne pollutants – are associated with intellectual deficits or behavioral problems in children, but the evidence is not as conclusive (Rauh, 2006; Engel, 2010; Eskenazi, 2007; Braun, 2009; Perera 2009; Herbstman, 2010). Much of this research was done by the NIEHS/US EPA Children’s Environmental Health Research Centers working collaboratively with the Centers for Disease Control and Prevention.
Children’s developing brains are more vulnerable to certain toxicants and pollutants than adults. The central nervous systems of the fetus and young child, which are undergoing rapid changes, are particularly vulnerable to some toxicants. The fetus is a recipient of toxicants through placental transfer (Perera et al. 2003; Whyatt and Perera 1995; Bearer 2003). In some cases, such as mercury, the fetus is exposed to a larger dose than the mother (Ramirez et al. 2000). In other cases, such as organophosphate pesticides, the fetus may lack critical enzymes to metabolize environmental toxicants (Chen et al. 2003). Toddlers are often at greater risk for exposure to many environmental toxicants because they have a high degree of hand-to-mouth activity and they absorb some toxicants more efficiently (Bearer 1995).