A Longitudinal Study of Environmental Effects on Child Health and Development Duane Alexander, M.D....
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Transcript of A Longitudinal Study of Environmental Effects on Child Health and Development Duane Alexander, M.D....
A Longitudinal Study of Environmental Effects on Child Health and Development
Duane Alexander, M.D.
U.S. Department of Health and Human Services
NICHD, CDC, NIEHS
U.S. Environmental Protection Agency
Children have increased vulnerability to environmental exposures
Critical windows of vulnerability during development
Immature mechanisms for detoxification and protection
Differences in metabolism and behavior that may yield higher exposure in the same environments
Known exposures of concern, and examples
Biological Infection in early life Metabolic
Physical Built environment Radiation
Psychosocial Abuse and neglect Family structure
Diet & Drugs Food additives Pharmaceuticals
Chemical Heavy metals Pesticides
Current Known Exposure Levels2nd National Report on Human Exposure to Environmental Chemicals*
Agent Level Threshold SampleMercury - Blood
0.34ug/L mean
15ug/L 705, 1-5 yrs
Phthlate, mono-ethyl (urine)
91.3ug/L mean
? 328, 6-11 yrs
PCB’s Not measured
<12 yrs.Phytoestrogen
Enterolactone
315ug/g creat.
(urine)
? 331, 6-11
Chlorpyrophos
metabolite
3.1ug/g creat.
(urine)
? 481, 6-11yrs
1 Napthol
90th %ile
4.5ug/g creat.
(urine)
? 483, 6-11yrs*http://www.cdc.gov/exposurereport/pdf/SecondNER.pdf
Important childhood conditions with suspected environmental components
Birth Defects Prematurity Autism Cerebral Palsy Type I diabetes Mental
retardation
Obesity Cancer Asthma Injuries Schizophrenia Learning
disabilities
President’s Task Force on Environmental Health Risks and Safety Risks to Children
Charged to develop strategies to reduce risk of environmental exposures to children
Co-chairs – Secretary HHS, Administrator USEPA
ConclusionsMany risks to children are poorly characterizedNeed for longitudinal study of environmental
effects New money would be required to carry out the
study
Rationale Converging factors
Increased vulnerability to environmental exposures in children in general
Exposures to some agents have caused serious developmental effects – lead, alcohol
Known current exposures of high frequency –
Existing research too limited in size & scope to answer the questions
Study needed to identify what is harmful, harmless and helpful to child development
Life-course design to correctly link with multiple exposures and multiple outcomes
PL 106-310 Children’s Health Act of 2000
(a) PURPOSE- . . . to authorize NICHD to conduct a national longitudinal study of environmental influences (including physical, chemical, biological, and psychosocial) on children's health and development.
(b) IN GENERAL- The Director of NICHD shall establish a consortium of representatives from appropriate Federal agencies (including the CDC and EPA) to--
(1) plan, develop, and implement a prospective cohort study, from birth to adulthood, to evaluate the effects of both chronic and intermittent exposures on child health and human development; and
(2) investigate basic mechanisms of developmental disorders and environmental factors, both risk and protective, that influence health and developmental processes.
. . .(e) AUTHORIZATION OF APPROPRIATIONS- There are authorized to be
appropriated to carry out this section $18,000,000 for fiscal year 2001, and such sums as may be necessary for each the fiscal years 2002 through 2005.
Study Concepts Longitudinal study of children, their families
and their environment
National in scope
Environment defined broadly (chemical, physical, behavioral, social, cultural)
Study of sufficient size to identify causal factors for important but less common outcomes (approx. 100,000 participants)
Application of the human genome project
Study Concepts (con’t)
State-of-the-art technology – tracking, measurement, data management
Consortium of multiple agencies
Extensive public-private partnerships
Hypothesis driven
National resource for future studies
Criteria for Core Hypotheses
No single hypothesis Hypothesis required for costly elements Important for child health & development
(prevalence, severity, morbidity, mortality, disability, cost, public health significance)
Reasonable scientific rationale Require the large sample size (~100,000)
Measurable with study of this size Requires longitudinal follow-up
Priority Outcome Areas (and example hypotheses)
Undesirable outcomes of pregnancy (Infection and mediators of inflammation during pregnancy are major causal factors associated with pre-term birth)
Neurobehavioral development (Low level pesticide exposure in utero is associated with impaired neurobehavioral and cognitive performance)
Injury (Repeated head trauma w/o anatomic damage is a causal factor for cumulative adverse effects on neurocognitive development)
Priority Outcome Areas (and example hypotheses)
Asthma (maternal stress during pregnancy is associated with the prevalence and severity of asthma in offspring)
Obesity and physical development (Obesity and insulin resistance is associated with impaired glucose metabolism in pregnancy, intrauterine growth restriction, and interacting factors in the physical and social environment)
Proposed Drug Abuse Hypotheses
Prenatal exposure to drugs will interact with family, child and other factors to influence cognitive, social/emotional and physical development.
Initiation of drug use, transition to abuse and addiction, and physical and mental consequences of drug use are influenced by certain environmental exposures including parent, child, and other factors.
Associations and Interactions in the National
Children’s StudyAsthma
Birth Defects
Development &
Behavior
Growth
Fertility & Pregnancy
Social Enviro
n
Physical
Environ
Infection
Chemical
Expos.
Medicine & Pharm
Health Care
Gene expressio
n
Measures Anticipated - Exposures
Environmental Samples: air, water, dust Bio-markers for chemicals: blood, breast
milk, hair, tissue, etc. Interview and history Serology and medical data Housing & living characteristics Family and social experiences Neighborhood and community
characteristics
Fetal growth and outcome of pregnancy Birth defects and newborn exam Growth, nutrition and physical
development Medical condition and history: illness (e.g.
asthma), conditions, & injuries
Cognitive and emotional development Mental, developmental and behavioral
conditions
Measures Anticipated –Outcomes
Use of Data to Maximize Output
Results available beginning 2008 Targeted hypotheses-testing
analyses Successive public-use data sets
with support Successive funding for investigator
initiated research and analyses Expected translation of results into
related prevention initiatives
National Children’s Study Organization of Planning Phase
Interagency leadership and funding – HHS (NICHD, NIEHS, CDC) & EPA
Dedicated staff at NICHD for operations
Federal Consortium of all HHS agencies + 12 other Departments and independent agencies
Chartered Federal Advisory Committee for advice and peer review
Working Groups (20) with approx. 250 scientists and experts for consultation and guidance re: hypotheses, design, measures
Network of all interested parties, 2,000+
-Extensive multi-agency collaboration-Broad scientific and advocacy input
Projected Time Line2000-2004 Planning, pilot studies, gather input
2001-2002 Form advisory committee and working groups
2003 Finalize central hypotheses, develop study design
2004 Select NCS study sites across the U.S.
2005 Begin participant enrollment
2008 First research results available
2008-2030+ Results continue; Translate into disease prevention strategies
Expected Benefits of the NCS
Condition Potential Reduction
Potential Annual Benefit
Pre-term Birth 10 % $0.6 Billion
Asthma 25 % $3.2 Billion
Obesity & Diabetes
12.5 % $14.5 Billion
Juvenile Diabetes
15 % $15 Billion
Injuries 10% $39 Billion
Schizophrenia 33 % $3.1 Billion
Reduced Learning
8% $100 Billion
The NCS will provide The answer to concerns about known exposures
during childhood to potential toxicants The power to determine absence of effects or benefit
of exposures to various products important for our economy
Causal factors for a number of diseases and conditions of children with suspected environmental causes
How multiple causes interact to result in multiple outcomes
Large sample size required to apply knowledge of the human genome to understand multifactoral genetic conditions
Identification of early life factors that contribute to many adult conditions
A national resource to answer future questions by using stored biological and environmental samples and the extensive data