Perchlorate Exposure from Diet and Drinking Water in a Representative Sample of the United States Population 2001 – 2008

  • 165 views
Uploaded on

Perchlorate (ClO4-) is ubiquitous in the environment and inhibits the thyroid’s uptake of iodide. Food and tap water are likely sources of environmental exposure to perchlorate. The aim of this study …

Perchlorate (ClO4-) is ubiquitous in the environment and inhibits the thyroid’s uptake of iodide. Food and tap water are likely sources of environmental exposure to perchlorate. The aim of this study was to identify significant dietary sources of perchlorate using perchlorate measured in urine as an exposure indicator. Sample-weighted, age-stratified linear regression models of National Health and Nutrition Examination Survey (NHANES) 2001–2008 data (n = 16,955 participants) characterized the association between urinary perchlorate and the mass consumed in USDA food groups, controlling for urinary creatinine and other potential confounders. Separate models of NHANES 2005–2006 data (n = 2,841) evaluated the association between urinary perchlorate and perchlorate consumed via residential tap water. Consumption of milk products was associated with statistically significant contributions to urinary perchlorate across all age strata: 2.93 ng ClO4-/ml per kg consumed for children (6–11 years-old (YO)); 1.54 ng ClO4-/ml per kg for adolescents (12–19 YO); and 0.69 ng ClO4-/ml per kg for adults (20–84 YO). Vegetables were a significant contributor for adolescents and adults, whereas fruits and eggs contributed significantly only for adults. Dark-green leafy vegetables contributed the most among all age strata: 30.83 ng ClO4-/ml per kg for adults. Fats, oils, and salad dressings were significant contributors only for children. Three food groups were negatively associated with urinary perchlorate: grain products for children; sugars, sweets, and beverages for adolescents; and home tap water for adults. In a separate model, however, perchlorate consumed via home tap water contributed significantly to adult urinary perchlorate: 2.11E–4 ng ClO4-/ml per ng perchlorate in tap water consumed. In a nationally representative sample of the United States 6–84 YO, diet and tap water contributed significantly to urinary perchlorate, with diet contributing substantially more than tap water.

Journal of Exposure Science and Environmental Epidemiology (2013) 23, 207–214; doi:10.1038/jes.2012.108
Keywords: perchlorate; NHANES; urine; water; diet

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Be the first to comment
    Be the first to like this
No Downloads

Views

Total Views
165
On Slideshare
0
From Embeds
0
Number of Embeds
0

Actions

Shares
Downloads
0
Comments
0
Likes
0

Embeds 0

No embeds

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
    No notes for slide
  • AbstractPerchlorate (ClO4-) is ubiquitous in the environment and inhibits the thyroid’s uptake of iodide. Food and tap water are likely sources of environmental exposure to perchlorate. The aim of this study was to identify significant dietary sources of perchlorate using perchlorate measured in urine as an exposure indicator. Sample-weighted, age-stratified linear regression models of National Health and Nutrition Examination Survey (NHANES) 2001–2008 data (n = 16,955 participants) characterized the association between urinary perchlorate and the mass consumed in USDA food groups, controlling for urinary creatinine and other potential confounders. Separate models of NHANES 2005–2006 data (n = 2,841) evaluated the association between urinary perchlorate and perchlorate consumed via residential tap water. Consumption of milk products was associated with statistically significant contributions to urinary perchlorate across all age strata: 2.93 ng ClO4-/ml per kg consumed for children (6–11 years-old (YO)); 1.54 ng ClO4-/ml per kg for adolescents (12–19 YO); and 0.69 ng ClO4-/ml per kg for adults (20–84 YO). Vegetables were a significant contributor for adolescents and adults, whereas fruits and eggs contributed significantly only for adults. Dark-green leafy vegetables contributed the most among all age strata: 30.83 ng ClO4-/ml per kg for adults. Fats, oils, and salad dressings were significant contributors only for children. Three food groups were negatively associated with urinary perchlorate: grain products for children; sugars, sweets, and beverages for adolescents; and home tap water for adults. In a separate model, however, perchlorate consumed via home tap water contributed significantly to adult urinary perchlorate: 2.11E–4 ng ClO4-/ml per ng perchlorate in tap water consumed. In a nationally representative sample of the United States 6–84 YO, diet and tap water contributed significantly to urinary perchlorate, with diet contributing substantially more than tap water. Journal of Exposure Science and Environmental Epidemiology (2013) 23, 207–214; doi:10.1038/jes.2012.108Keywords: perchlorate; NHANES; urine; water; diet
  • Direct consumption of contaminated waterCrops grown with contaminated water, fertilizer or soilFood cropsForage cropsMap 1 presents the national map of perchlorate detections in drinking water. This map is a compilation of all perchlorate detections in drinking water extracted from the August, 2004 UCMR data and from studies performed by the states of California, Massachusetts and Texas. Data from the Arizona study did not distinguish between potable and non-potable sources. For this reason it is not included on the map, but will be analyzed in detail later.PERCHLORATE OCCURRENCE MAPPING Submitted by: Philip Brandhuber Ph.D Sarah Clark PE HDR Denver, Colorado Submitted to: American Water Works Association Washington, DC January, 2005
  • The sodium-iodide symporter:Mode of action: Active transport of iodide across cell membrane using sodium ion gradientTissues with NIS expression: >Thyroid, Placenta, Mammary gland: relevance to bovine lactation as well: Perchlorate concentrated into milk.ClO4- is transported by NIS 30-fold more avidly than iodide NIS Inhibitors: Perchlorate, thiocyanate and nitrateThe better characterize the potential health effects of perchlorate exposure, we need to quantify all of the physiologically relevant anions that can interact with the sodium-iodide symporter: iodide, perchlorate, thiocyanate and nitrate.NiS and Pendrin both transport perchlorate across cell membranes: thus known thyroid inhibition and concern about breast fed infant’s intake dose of perchlorate
  • National Health and Nutrition Examination Survey (NHANES)Physical exam and tissue sampling QuestionnaireBiomonitoringHealth conditions and behaviorsRepresentative sample ofUnited States , nationwideNon-institutionalized CivilianCross-sectional prevalenceUse of weighting, clustering, and stratificationOversamplingVariance estimation complicatedSpecial software: SUDAAN™Taylor series linearization method (GEE)WeightingThe statistical weight of a sampled person is the number of people in the population that the person represents. Weights derived fromSelection probabilitiesResponse ratesPost-stratification adjustment e.g., gender, education, income, regionStratificationPopulation divided before sampling into disjoint, exhaustive groups (strata)Members termed primary sampling units (PSUs) Independent samples are taken in each strataStrata formed by similar geographic areas  e.g., NHANES: partition US counties into 49 strata based on region and economic/racial characteristicsSample 2 counties (PSUs) from each strataClusteringPersons residing in a small area may have similar characteristicsThus, responses of subjects in small area are potentially correlated Correlation must be accounted for in the analysis Survey analysis programs do this through strata/PSU informationVariance EstimationLinearization: Uses a Taylor series expansion to estimate variance of non-linear estimators Default method for most programsRequires stratification and PSU information
  • National Health and Nutrition Examination Survey (NHANES) 2001 — 2008Physical exam and tissue sampling QuestionnaireBiomonitoringHealth conditions and behaviorsRepresentative sample ofUnited States , nationwideNon-institutionalized CivilianCross-sectional prevalenceUse of weighting, clustering, and stratificationOversamplingVariance estimation complicatedSpecial software: SUDAAN™Taylor series linearization method (GEE)WeightingThe statistical weight of a sampled person is the number of people in the population that the person represents. Weights derived fromSelection probabilitiesResponse ratesPost-stratification adjustment e.g., gender, education, income, regionStratificationPopulation divided before sampling into disjoint, exhaustive groups (strata)Members termed primary sampling units (PSUs) Independent samples are taken in each strataStrata formed by similar geographic areas  e.g., NHANES: partition US counties into 49 strata based on region and economic/racial characteristicsSample 2 counties (PSUs) from each strataClusteringPersons residing in a small area may have similar characteristicsThus, responses of subjects in small area are potentially correlated Correlation must be accounted for in the analysis Survey analysis programs do this through strata/PSU informationVariance EstimationLinearization: Uses a Taylor series expansion to estimate variance of non-linear estimators Default method for most programsRequires stratification and PSU information
  • Adult food model controls for additional age intervals20 – 39 YO40 – 59 YO60 – 84 YOChildren food model does not control for tobacco/nicotine useChildren not asked in NHANES
  • Most important food groups for median dietChildren 6 – 11 YO: milk productsAdolescents 12 – 19 YO: milk productsAdults 20 – 84 YO: Vegetables

Transcript

  • 1. Perchlorate Exposure from Diet andDrinking Water in a Representative Sampleof the United States Population 2001 – 2008B.Rey de Castro,Sc.D.Statisticianbefore theAWWA Annual Conference and Exposition 2013Drinking Water & Public HealthThursday,June 13,2013Denver, CONational Center for Environmental HealthDivision of Laboratory Sciences
  • 2. What food groups pose the greatest riskfor perchlorate exposure?For the US median dietary intake,what food groups pose the greatest riskfor perchlorate exposure?What is the contribution of drinking waterto dietary exposure to perchlorate?
  • 3. OverviewFood ModelsDrinkingWater Models• Urine perchlorate per massfood eatenAim• NHANES 2001 - 2008• 16,955 participantsData• Children• Adolescents• AdultsAge Strata• Food model slopes• Median food consumptionUSMedianDiet• Urine perchlorate pertap water perchloratedrankAim• NHANES 2005 - 2006• 2,841 participantsData• Adolescents• AdultsAgeStrata
  • 4. • Component of rocketpropellant• Explosives,fireworks,roadflares,dyes,leathertanning,matches• Forms naturally in atmosphere
  • 5. Perchlorate Detection in Drinking WaterData: US EPA UCMR 2004,CA,MA,TXPerchlorate Occurrence Mapping, AWWA, January 2005
  • 6. Perchlorate Inhibits Iodide Uptakeat Sodium-Iodide Symporter (NIS) Active transport Perchlorate 30x>> Iodide Tissues with NIS Thyroid Placenta Mammary gland Perchlorateconcentrated in milk Other inhibitors Thiocyanate Nitrate
  • 7. Human Metabolism and Excretion Perchlorate not metabolized by humans Unlikely to bioaccumulate significantly Excreted primarily in urine ~8 hour half-life Excretion via milk 24-hr urine approximates daily intake Non-lactating people
  • 8. NHANESNationally Representative Sample
  • 9. NHANES24-hour Diet Recall
  • 10. Linear Regression Outcome Urinary perchlorate concentration Spot urine sample ng/ml
  • 11. USDA Food Groups,adapted Milk Products Meat,Poultry,Fish Eggs Legumes,Nuts,Seeds Grain Products Fruits Fats,Oils,Salad Dressings Vegetables Dark-green Leafy Vegetables Sugars,Sweets,Beverages Water (Not Bottled) at Home
  • 12. Control for Potential Confounders Urinary creatinine Sex Race Body mass index Poverty income ratio Education Fasting time Tobacco/nicotine use in five days prior to examination Diet intake day NHANES study cycle
  • 13. Slopes and confidence limitsestimated on linear scale,but statistical significanceassessed on loge scale. Slopes readily interpretable But,confidence limits do not reflect skewed data p-Values sensible for skewed data
  • 14. Drinking Water Models Tap water perchlorate measured directly Diet assessed comprehensively Systematic recall of food eaten in previous 24-hours NHANES Individual Foods – First Day Two age-stratified models Adolescents 12 – 19 YO Adults 20 – 84 YO Data NHANES 2005–2006 data 2,841 participants Control for significant confounders only
  • 15. Drinking Water Model Slopes
  • 16. Food Models Diet assessed comprehensively Systematic recall of food eaten in previous 24-hours NHANES Individual Foods – First Day Three age-stratified models Children 6 – 11 YO Adolescents 12 – 19 YO Adults 20 – 84 YO Data NHANES 2001 – 2008 16,955 participants Control for multiple confounders
  • 17. Food Model SlopesAdults 20 – 84 years-old
  • 18. Food Model SlopesAdults 20 – 84 years-oldSlope units: ng perchlorate/mL per kg food consumed
  • 19. Food Model SlopesAdults 20 – 84 years-oldSlope units: ng perchlorate/mL per kg food consumed
  • 20. Food Model SlopesAdults 20 – 84 years-oldSlope units: ng perchlorate/mL per kg food consumed
  • 21. Food Model SlopesAdolescents 12 – 19 years-oldSlope units: ng perchlorate/mL per kg food consumed
  • 22. Food Model SlopesAdolescents 12 – 19 years-oldSlope units: ng perchlorate/mL per kg food consumed
  • 23. Food Model SlopesAdolescents 12 – 19 years-oldSlope units: ng perchlorate/mL per kg food consumed
  • 24. Food Model SlopesChildren 6 – 11 years-oldSlope units: ng perchlorate/mL per kg food consumed
  • 25. Food Model SlopesChildren 6 – 11 years-oldSlope units: ng perchlorate/mL per kg food consumed
  • 26. Food Model SlopesChildren 6 – 11 years-oldSlope units: ng perchlorate/mL per kg food consumed
  • 27. Food Model SlopesSign p-Value Children (6 - 11 years-old) Adolescents (12 - 19 years-old) Adults (20 - 84 years-old)PositiveSignificantFats, Oils, Salad DressingsMilk Products19.022.93VegetablesMilk Products2.111.54Dark-Green Leafy VegetablesEggsVegetablesFruitsMilk Products30.834.392.621.210.69Marginally SignificantDark-Green Leafy VegetablesFruits11.470.56NegativeMarginally SignificantSugars, Sweets, Beverages -0.13SignificantGrain Products -1.19Sugars, Sweets, Beverages -0.33Water (Not Bottled) At Home -0.20
  • 28. Total Exposure from US Median DietFood ModelSlopeUS MedianMass Eaten
  • 29. Total Exposure from US Median Diet
  • 30. Total Exposure from US Median Diet
  • 31. Total Exposure from US Median DietAge at ScreeningFood Group 6 – 11 YO 12 – 19 YO 20 – 84 YOMilk Products 0.90 0.33 0.09Meat,Poultry, Fish 0.07 0.05 -0.008Eggs 0 0 0Legumes,Nuts,Seeds 0 0 0Grain Products -0.31 -0.17 -0.12Fruits 0.07 0 0.06Vegetables 0.04 0.15 0.34Dark-green Leafy Vegetables 0 0 0Fats,Oils,Salad Dressings 0 0 -0.003Sugars,Sweets,Beverages -0.17 -0.30 -0.17Water (Not Bottled) at Home 0 0 0NET TOTAL 0.60 0.06 0.17
  • 32. Drinking water contributes relatively little tothe dietary exposure of perchlorateWhat is the contribution of drinking waterto dietary exposure to perchlorate?
  • 33. What food groups pose the greatest riskfor perchlorate exposure?Dark-green leafy vegetables;fats,oils,salad dressings; eggs;milk products;vegetables;and fruitsThe food groups of greatest risk vary by age
  • 34. For the US median dietary intake,what food groups pose the greatest riskfor perchlorate exposure?Milk products and vegetablesChildren 6 – 11 years-old have highestnet dietary exposure to perchlorate
  • 35. Collaborators CDC National Center for Environmental Health Division of Laboratory Sciences Benjamin C.Blount Fiona K.Lau K.Udeni Alwis Lavinia Mills-Herring Lin Tao Liza Valentín-Blasini
  • 36. J Expo Sci Environ Epidemiol. 2013 Mar;23(2):207-14.PMID:23188482
  • 37. B.Rey de Castro, Sc.D.+1 770 488 0162rdecastro@cdc.govFor more information please contact Centers for Disease Control and Prevention1600 Clifton Road NE, Atlanta, GA 30333Telephone: 1-800-CDC-INFO (232-4636)/TTY: 1-888-232-6348E-mail: cdcinfo@cdc.gov Web: http://www.cdc.govThe findings and conclusions in this presentation are those of the authors and do not necessarily represent the official positionof the Centers for Disease Control and Prevention.National Center for Environmental HealthDivision of Laboratory SciencesLinkedIn ContactSlideShare Presentation