Children & Chronic Disease

Patterns of illness among children in the industrially developed nations have changed substantially in the past one hundred years. Infant mortality has declined. Life expectancy has increased. Today the major diseases confronting children are a group of chronic conditions that are termed the "new pediatric morbidity". These include:

• Asthma, which has more than doubled in frequency since 1980;
• Birth defects, which are the leading cause of infant death. Certain birth defects, such as hypospadias, have increased sharply in frequency;
• Neurodevelopmental disorders, such as dyslexia, mental retardation, attention deficit/ hyperactivity disorder (ADHD) and autism, which affect 5-10% of the 4 million babies born each year in the United States;
• Leukemia and brain cancer in children and testicular cancer in adolescents, all of which have increased in incidence since the 1970s despite declining mortality;
• Obesity and type 2 diabetes, which have become epidemic in American children.

Children & Chemicals

The environment in which children live has also changed. Today there exist more than 80,000 synthetic chemicals, most of them invented since the 1950's. They include plastics, pesticides, motor fuels, building materials, antibiotics, chemotherapeutic agents, flame retardants and synthetic hormones. Children are disproportionately exposed to these chemicals, because of their dietary patterns and their unique age-related behaviors - their play close to the floor and their oral exploratory behavior. Children are especially at risk of exposure to the 3,000 synthetic chemicals that are produced in quantities of 1 million tons or more per year. These high-production-volume (HPV) chemicals are the synthetic materials dispersed most widely in the environment -- in air, food, water, and consumer products in homes, schools and communities. In recent national surveys, quantifiable levels of a number of HPV chemicals have been detected in the bodies of most Americans.

Little is known of the potential toxicity of many of the chemicals to which children are at risk of exposure. Only about half of the HPV chemicals have been tested for their potential to cause toxicity and fewer than 20% for their potential to interfere with development. This lack of information creates a setting in which chemicals can cause unanticipated adverse effects, especially when exposures occur during embryonic or fetal life or in the first years after birth. Examples of past tragedies resulting from early life exposures to untested chemicals include phocomelia in infants exposed to thalidomide; adenocarcinoma of the vagina in girls exposed to diethylstilbestrol (DES); neurodevelopmental toxicity in infants exposed to lead, PCBs, methyl mercury and ethyl alcohol; and small head circumference at birth in infants exposed to organophosphate pesticides.

Children & Prevention

Despite recent gains in knowledge of environmental contributions to the causation of chronic disease in children, major questions about the impact of the environment on children's health remain unanswered. Little is known about patterns of exposure in embryonic and fetal life. Almost nothing is known about possible interactions and synergies among chemicals or between chemicals and other environmental hazards. The long-term consequences of early life exposures are just beginning to be explored.

Risk assessment paradigms that account for the unique exposures and special vulnerabilities of children are only now beginning to be developed. There almost certainly exist additional etiologic associations between the environment and disease in children that have not yet been discovered. Particular interest surrounds study of interactions between the environment and the human genome. Progress will require a multi-pronged strategy:

• Testing chemicals for toxicity
• Disease tracking
• Research
• Training of health care providers
• Patient care
• Prevention