Journal Issue: Children with Disabilities Volume 22 Number 1 Spring 2012
Why Focus on Preventing Disabilities in Children?
Children are particularly vulnerable to environmental stressors; they pass through several delicate developmental stages and, pound for pound, they eat and breathe more environmental contaminants than adults.10 An exposure that is innocuous in adults can have a dramatic effect when it occurs during fetal development or early childhood. For example, in the mid-1900s thalidomide was prescribed to treat morning sickness in thousands of pregnant women, at doses that were nontoxic for adults. But the drug had devastating effects on their fetuses, especially when administered between twenty-seven and forty days after conception, when limb development occurs. While thalidomide causes gross deformities, many other environmental exposures that occur during fetal development and childhood can have substantial lifelong implications among a population of children, even if the effects are subtle for an individual child. Unfortunately, these effects are much less likely to be recognized and addressed; David Rall, former director of the National Institute of Environmental Health Sciences, once remarked, "If thalidomide had caused a ten-point loss of IQ instead of obvious birth defects of the limbs, it would probably still be on the market."11
Exposures that occur during fetal development or early childhood can obstruct or retard normal function. Children's lungs, for example, continue to develop from birth throughout adolescence, and lung function increases throughout childhood, reaching a peak in the late teens or early twenties (figure 1). Then it plateaus for several years before it begins to gradually decline in older adulthood. Several recognized risk factors can alter lung function over the life span. One risk is prenatal exposure to tobacco smoke, which lowers lung function in childhood as well as peak lung function.12 Similarly, exposure to air pollution has been associated with reduced lung function.13 Children who face multiple risk factors that diminish their lung function are at higher risk of meeting a threshold associated with chronic respiratory disease. Put another way, insults in early development can impair or obstruct function throughout the life span, leading to diminished function and accelerated disability at older ages. This relationship between early-life insults and later disability occurs in other chronic conditions, such as lead-associated cognitive deficits and dementia, or lower bone mineral density and earlier-onset osteoporosis associated with calcium-deficient diets.14
Although Americans' life expectancy has increased, so have the years many of them live with a disability or chronic disease.15 Many factors undoubtedly account for this increase in disability, but environmentally induced conditions incurred during childhood can compound throughout a person's lifetime and express themselves as chronic diseases in adulthood or old age. Today's increases in childhood obesity will lead to tomorrow's epidemics of diabetes in young adults and to cardiovascular disease in middle-aged or older adults.16 The emerging evidence thus suggests that preventing the development of chronic disease in adults requires improving the health of children. That, in turn, will require dramatic shifts of resources for a country that spends the vast majority of its health care dollars for medical treatment of the elderly.17
Another reason to focus on prevention in children is because disabilities in children are on the rise (see the article in this volume by Neal Halfon and others).18 The definition of disability varies depending on the survey used, but the number of children diagnosed with an activity limitation stemming from a chronic health condition rose from 1.8 percent in 1960 to 7.3 percent in 2006, while the prevalence of diagnosed developmental disabilities rose from 12.8 percent in 1997–99 to 15 percent in 2006–08.19 Many of the most common disabilities, including asthma, premature birth, autism, attention-deficit/hyperactivity disorder (ADHD), and obesity, appear to be on the rise.20
A shift to prevention of disabilities should be attractive to policy makers because prevention reduces health care and societal costs, as well as alleviating human suffering. For example, lead in house paint is known to be associated with lower IQ and ADHD in children and with criminal behavior in adulthood.21 Policy makers may balk at requiring homeowners, landlords, and others to undergo the expense and effort of removing the hazard, yet a cost-benefit analysis concluded that every $1 spent to reduce lead hazards in housing would produce between $17 and $221 in benefits by reducing expenditures on screening and treatment for lead toxicity, ADHD treatment, and special education; increasing income and tax revenue; and reducing crime. The analysis estimated a total potential net savings from the elimination of lead hazards of $118 billion to $269 billion.22 Another study estimated the cost of disease from exposure to pollutants linked with asthma, cancer, and neurobehavioral disorders at $76.6 billion in a single year (2008).23
The Epidemiologic Transition and the Emergence of the New Morbidities
To understand the causes of the "new morbidities," or disabilities, of childhood, it is useful to examine trends in patterns of disease and disability over the past century. As noted, in the early 1900s public health concerns were dominated by epidemics of infectious disease, overt nutritional deficiencies, and infant mortality associated with poor urban living conditions. With the advent of public water and sanitation systems, pasteurization of milk, and housing safety codes, death rates fell sharply, especially among infants and children, and life expectancy in the United States increased from forty-seven years in 1900 to sixty-eight years by 1950, and to seventy-eight years in 2007.24 Moreover, the pattern of mortality and morbidity shifted from infectious diseases to chronic conditions such as cardiovascular disease and cancer, a shift commonly known as the epidemiologic transition.25 In recent years, a similar transition has been taking place for children, as the burden of illness and disability shifts from infectious disease to chronic conditions including asthma, obesity, and mental health and neurobehavioral problems such as autism and ADHD.