Persistent Bioaccumulative Toxicants Workshop Larry L. Needham, PhD National Center for Environmental Health Centers for Disease Control and Prevention April 22, 2002
Mission of Division of Laboratory Sciences To develop and apply analytical methods for assessing human exposure to environmental chemicals (and ultimately to be a team member for preventing / reducing morbidity and/or mortality in the US population.
Mission statement (cont.) To address this mission, we collaborate with investigators within CDC, other federal agencies, state health departments, international agencies, academia, and industry. One of needs is to acquire background levels of environmental chemicals in human populations.
National Report on Human Exposure to Environmental Chemicals Division of Laboratory Sciences, National Center for Environmental Health, CDC
Organization for NHANES DHHS FDACDCNIH NCID NC CDPHP NCHS NC HIV,STD, &TB NIOSHNCIPCNCEH
23 Participating Laboratories for NHANES NHANES MEC Division of Laboratory Sciences / NCEH NCID labs NCHSTP Medical Research Centers/ Academic labs Commercial labs
Eligible NHANES Population Civilian, non-institutionalized population of the United States Ages 2 months and older Residents of all 50 states and DC 5000 persons examined each year in 15 locations Survey design determines which populations are over-sampled
How did NHANES start? The Health Examination Survey – the forerunner in the 1960’s HANES I – 1971; Nutrition added as a major component
Six Principal Data Collection Methods Household interview Personal interviews Physical examination Anthropometry Diagnostic screening Laboratory analysis
The Mobile Examination Centers (MECs)
4 Trailers attached to one another, each ~ 8’x45’ 3 Sets: 2 in operation at any given time 15 sites visited each year, 4-6 wk/location Survey design: Northern U.S. states in summer, Southern states in winter Average of 450 sample persons per survey location Provides standardized environment 20 Examinations per day in two sessions per day, (morning/afternoon or morning/evening), Wed-Sun
MEC examination components Dietary interviews/MEC interviews Phlebotomy Urine collection Blood pressure Physician’s exam Hearing Eye exam Dental exam DXA Muscle strength Balance Anthropometry Skin disease/Melanoma TB skin test Cognitive testing Cardiorespiratory fitness Peripheral vascular disease Peripheral neuropathy
NHANES Laboratory in the MEC Coulter Counter for CBC Laminar Flow Hood
CDC NCHS MEC CDC CASPIR CDC NCEH DLS
What Purpose Does NHANES Serve? Serves as a warning system for health problems
Urinary Iodine levels Monitoring of iodine levels through NHANES can provide a warning of thyroid deficiency trends Studies show that median iodine levels in the population are dropping due to decreased food iodization from salt Health problems could occur if trend continues
What Purpose Does NHANES Serve? Helps identify who is at risk.
Distribution of serum cotinine in the U.S. Population (ages 4 and older), NHANES III ( ) Serum cotinine (ng/mL) Percent of the Population Smokers Nonsmokers
No reported home or work ETS exposure Reported home or work ETS exposure Percentage of the Population Serum Cotinine Levels in the U.S. Population by Self- reported Exposure to Tobacco Smoke, NHANES III ( )
What Purpose Does NHANES Serve? Shows if public health interventions have been successful through trend data.
Year Lead used in gasoline (thousands of tons) Gasoline lead Lead used in gasoline declined from 1976 through 1980
Year Mean blood lead levels (ug/dL) Gasoline lead Predicted blood lead Lead used in gasoline (thousands of tons) Environmental Modeling Predicted Only a Slight Decline in Blood Lead Levels in People
Observed blood lead Year Gasoline lead Predicted blood lead Lead used in gasoline (thousands of tons) Mean blood lead levels (ug/dL) NHANES II Blood Lead Measurements Found a Substantial Decline in Blood Lead Levels, 10 Times More Than Predicted From Environmental Modeling
Year Blood lead Gasoline lead Lead used in gasoline (thousands of tons) Mean blood lead levels (ug/dL) NHANES III ( ) Blood Lead Measurements Showed That After NHANES II ( ), Blood Lead Levels Continued to Decrease As Gasoline Levels Declined
Percent of children with blood lead levels <10 ug/dL NHANES II NHANES III Blood lead levels in NHANES surveys: children 1- 5 years
How was it proven that the declining blood lead levels were due to changes in the environment, and not due to analytical errors? MEASUREMENT OF LONG-TERM, STABLE QUALITY CONTROL MATERIALS CALIBRATED AGAINST NIST SRMs
What purpose does NHANES serve? In toxicology studies – helps prioritize.
Methyl Eugenol Occurs naturally in clove oil, nutmeg, allspice, walnuts Uses: Flavoring agent, insect attractant, fragrance (30,000 kg/yr) Consumption Rate: 6 g/day OCH 3
DLS’ Commitment to Analyses for NHANES Has Increased With Each Successive Survey HANES I - 20,000 subjects NHANES Central Laboratory established Strictly nutrition-oriented survey 22 Analytes measured, all at CDC Hematology a primary component; CBC done in MEC Abell-Kendall reference cholesterol method used HANES II - 20,000 subjects Six outside labs are added 21 analytes measured; blind QC added Trace metals added (Pb, Zn, Cu) Hepatitis and STD prevalence first assessed EPA assessed human exposure to OC and OP pesticides and phenols.
DLS’ commitment to analyses for NHANES has increased with each successive survey Hispanic HANES - 12,000 subjects Mexican-American, Cuban, Puerto-Rican subjects Four outside labs 37 Analytes measured, HPLC debuts Hair collection for trace metals added EPA assessed human exposure to OC and OP pesticides and phenols.
DLS’ commitment to analyses for NHANES has increased with each successive survey NHANES III - 30,000 subjects 12 contract labs First survey to use bar codes 85+ Analytes; cotinine is major component Lab manual is >700 pages and is published on CD-ROM) RBase used for survey database; still using mainframe LN2 storage introduced for reserve serum aliquots Selenium, Genetics component added Subset for VOCs and pesticide metabolites.
National Report on Human Exposure to Environmental Chemicals Division of Laboratory Sciences, National Center for Environmental Health, CDC
National Report on Human Exposure to Environmental Chemicals MatrixAge RangeNAssessment Blood 1 year 3,189Pb, Cd Blood1-5 years248Hg Blood16-49 years (F)679Hg Urine 6 years ~1000Sb, BA, Be, Cd, Ce, Co, Pb, Mb, Pt, Th, W, U Urine 6 years ~1000OPs (6), Phthalates (7) Serum 3 years 2263cotinine
National Report on Human Exposure to Environmental Chemicals –1999/2000 MatrixAge RangeNAssessment Blood 1 year Pb, Cd Blood1-5 yearsHg Blood16-49 years (F)Hg Blood 12 years VOCs Serum 3 years cotinine Serum 12 years PCBs (38), PCDDs (7), PCDFs (10), coplanar PCBs (4), OC insecticides (10) Serum 12 years Se Urine 6 years Sb, Ba, Be, Cd, Ce, Co, Pb, Mb, Pt, Th, W, U, Hg Urine 6 years OPs (6), Phthalates (7), PAHs (18), Phytoestrogens (8), additional NPPs
Does the test have biological relevance? Is there a correlation between the biomarker and dietary intake or exposure data? Does the condition occur frequently enough in the population? Is there a validated method available? Can we afford the cost of the assay? Is there financial support for the assay? Primary Criteria for Consideration for Inclusion of Analytes in NHANES
Exposure Pathway (Partial) for Toxicant Source Environmental Fate and Transport Exposure Absorption Barriers Air, Water, Food, Soil, Surfaces GI tract wall Lung tissue Skin Internal Dose Biological Effective Dose
Life Cycle Conception Birth Death 1 y 2 y 3 y 6 y 12 y y Infancy Young toddler Older toddler Preschool Pre High School Adolescence Trimesters Embryonic (8d – 8w)