Philip Landrigan, MD: The National Children's Study is an extraordinary endeavor. It's the largest most complex study of children's health ever undertaken in the United States. The plan is to enroll 100,000 children all across the United States and follow them from early in pregnancy out to age 21. The purpose of the study is to determine all the environmental factors that cause disease in children. So the study is intended to discover what are the early environmental exposures that cause asthma, that cause birth defects, that cause low birth weight, that cause prematurity. The study is trying to discover what are the environmental exposures during pregnancy and early childhood that may trigger autism, attention deficit disorder, other learning disabilities in children, even looking for the environmental linkages to childhood cancer. It's a very broad study. And then the plan is that as the children grow up we do very careful physical exams; at birth, at one year, two years, three years, five years, eight years and so on out with the intention of linking exposures in the womb, exposures in early childhood to disease that occurs 3, 5, 15, 20 years later. It's a terribly important study. And it's an extraordinary opportunity for pediatricians, parents, all Americans to learn a huge amount about the intersection between the environment and children's health. It's a wonderful thing for this country that we're doing it, we're really leading the world in taking on this study.