Good morning. I am Duane Alexander, Director of the National Institute of Child Health and Human Development (NICHD) at the National Institutes of Health. I appreciate the opportunity to testify before the committee today on an issue that has far reaching implications for the health of our children, now and in the future.
The relationship of the environment to our health has long been a focus of the NICHD's mission and research agenda, from discovering possible environmental causes of infertility, to the identification and reduction of exposures to various chemicals during pregnancy in order to foster the birth of healthy children, to the maintenance of a safe environment that prevents injury and promotes healthy living habits enabling children to reach adulthood healthy and free of disability. We have made progress in many areas – fewer and fewer children have elevated blood lead levels, cribs are safer for babies to sleep in because soft materials that pose suffocation risks have been removed, and life-threatening ingestions of prescription drugs and aspirin have been decreased dramatically with the development and wide use of childproof safety containers. Our health habits have improved in some areas – helmets and seatbelts are being worn more commonly, preventing many serious injuries, and we have learned important information about the value of adequate calcium consumption to prevent osteoporosis, and of avoiding cigarette smoke. Nonetheless, as the range of environmental exposures continues to expand, much remains to be done.
Ongoing Research
I would like to highlight a few of the research initiatives in this area in which NICHD is currently involved:
- Scientists in our intramural program are examining the long-term effects of in utero exposure to certain compounds, specifically PCBs and DDE (a breakdown product of DDT). These compounds, which are detectable in humans worldwide, have been suggested as causing impaired neurodevelopment in children, such as suboptimal muscle tone, slower reflexes, reduced IQ levels and hearing loss.
- Along similar lines, research supported by the NICHD is taking a closer look at whether exposure to environmental chemicals or medications taken by a woman in the last month of pregnancy, or during the period in which she is breastfeeding her infant, may be producing subtle, but irreparable damage to her child later in life. This work may prove critical to women who are hoping to breastfeed their babies, but who may have been exposed to certain medications or other chemicals.
- An NICHD-funded study is under way to assess the impact of maternal exposure to tobacco smoke and other specific lifestyle factors on fetal development and the likelihood of genetic mutations. There is some evidence that such exposure early in fetal life may cause damage to genes that later serve to protect against the development of cancerous tumors.
- Only a handful of studies to date have looked at the impact of diet and environmental factors on the risk of developing high blood pressure in pregnancy, which is hazardous to both mother and fetus. A new NICHD-supported study will give us valuable information on whether caffeine or alcohol consumption, or occupational exposure to certain solvents, during pregnancy increases the risk of high blood pressure, and whether leisure time physical activity confers protection against pregnancy-related hypertension.
Future Plans
For the past several years, we have been laying the groundwork for several major initiatives that will contribute new knowledge about the impact of environmental factors on children's – and adults' – health.
In April 1997 President Clinton issued Executive Order 13045 that established a Task Force on Environmental Health Risks and Safety Risks to Children. One of the four areas being emphasized by the Task Force is developmental disorders. Two of the NICHD's major initiatives are direct outgrowths of this effort.
The first is a significant commitment of additional resources to the study of the causes of birth defects. It is estimated that more than 150,000 babies in the U.S. each year (about 4 percent of all live births) are born with significant birth defects. From the beginning, NICHD's mission has included the study of the causes of disruptions to normal developmental processes. As part of our cooperative efforts with the Task Force, we will be focusing intensive efforts on clarifying the causes of birth defects, and coordinating multidisciplinary research for reducing their occurrence.
In May 1999 the NICHD, together with the National Institute of Environmental Health Sciences (NIEHS), the National Institute of Dental and Craniofacial Research (NIDCR), and the Environmental Protection Agency (EPA), issued a Request for Applications (RFA) on the Genetic Susceptibility and Variability of Human Malformations. Proposals funded under this RFA in FY 2000 will be looking at the genes that are involved with causing structural birth defects, such as congenital heart disease, neural tube defects (including spina bifida), cleft lips and palates, and other malformations. An important component of this research will be determining the impact of environmental factors on genes in causing birth defects.
While we are trying to determine what causes normal developmental processes to be disrupted, we are also planning to delve further into the underlying mechanisms that contribute to normal development. Successful proposals responding to a second RFA on Developmental Mechanisms of Human Malformations, issued by NICHD and NIEHS in October 1999, will look for "candidate genes" whose mutations in animal models may result in various types of birth defects. Among the proposals we expect to receive are those that will examine the impact of environmental factors on genetic mutations, and thus, on the resulting malformations.
Our second major initiative, I am very pleased to report, is no longer just a dream, but is well on the way to becoming reality. As you know, children are more vulnerable than adults to hazards in their environments. The effects of children's environmental exposures may be subtle or pronounced, observable immediately or not until years after the exposure occurs. The scientific knowledge necessary for creating and maintaining a healthy and safe environment for children and families will be best accumulated by developing a research strategy that measures the physical, chemical, biological, and psychosocial environmental influences across the life span, longitudinally, beginning before birth. We are now planning to conduct just such a study, with the strong endorsement of the Task Force chairs, Department of Health and Human Services Secretary Donna Shalala and EPA Administrator Carol Browner.
As envisioned, the National Longitudinal Study of Environmental Influences on Child Health would enroll approximately 100,000 children, beginning during a woman's pregnancy, gathering data on prenatal and postnatal environmental influences and child health outcomes until at least age 21. It will be the largest such prospective study ever undertaken. Developed jointly by a consortium of federal agencies, with leadership from NICHD, CDC, and EPA, the knowledge gained from this study, combined with human genome sequencing, will provide a national resource to be widely disseminated and applied to policies, programs, and care standards making our children's future brighter, healthier and safer. Such a study will be expensive, but it is the only way to answer many important questions about health and the environment, and the expected payoff is far greater than the investment. Planning is currently under way, and initial pilot testing is scheduled for FY 2001.
Mr. Chairman, thank you again for this opportunity to discuss our efforts in this area. We appreciate your vision, leadership and encouragement. I would be happy to answer any questions you might have.
