title: Geographic clustering of elevated blood heavy metal levels in pregnant women.
abstract: BACKGROUND
  Cadmium (Cd), lead (Pb), mercury (Hg), and arsenic (As) exposure is ubiquitous and has been associated with higher risk of growth restriction and cardiometabolic and neurodevelopmental disorders. However, cost-efficient strategies to identify at-risk populations and potential sources of exposure to inform mitigation efforts are limited. The objective of this study was to describe the spatial distribution and identify factors associated with Cd, Pb, Hg, and As concentrations in peripheral blood of pregnant women.
  
  
  METHODS
  Heavy metals were measured in whole peripheral blood of 310 pregnant women obtained at gestational age ~12 weeks. Prenatal residential addresses were geocoded and geospatial analysis (Getis-Ord Gi* statistics) was used to determine if elevated blood concentrations were geographically clustered. Logistic regression models were used to identify factors associated with elevated blood metal levels and cluster membership.
  
  
  RESULTS
  Geospatial clusters for Cd and Pb were identified with high confidence (p-value for Gi* statistic <0.01). The Cd and Pb clusters comprised 10.5 and 9.2 % of Durham County residents, respectively. Medians and interquartile ranges of blood concentrations (μg/dL) for all participants were Cd 0.02 (0.01-0.04), Hg 0.03 (0.01-0.07), Pb 0.34 (0.16-0.83), and As 0.04 (0.04-0.05). In the Cd cluster, medians and interquartile ranges of blood concentrations (μg/dL) were Cd 0.06 (0.02-0.16), Hg 0.02 (0.00-0.05), Pb 0.54 (0.23-1.23), and As 0.05 (0.04-0.05). In the Pb cluster, medians and interquartile ranges of blood concentrations (μg/dL) were Cd 0.03 (0.02-0.15), Hg 0.01 (0.01-0.05), Pb 0.39 (0.24-0.74), and As 0.04 (0.04-0.05). Co-exposure with Pb and Cd was also clustered, the p-values for the Gi* statistic for Pb and Cd was <0.01. Cluster membership was associated with lower education levels and higher pre-pregnancy BMI.
  
  
  CONCLUSIONS
  Our data support that elevated blood concentrations of Cd and Pb are spatially clustered in this urban environment compared to the surrounding areas. Spatial analysis of metals concentrations in peripheral blood or urine obtained routinely during prenatal care can be useful in surveillance of heavy metal exposure.
authors.affiliation: Biodemography of Aging Research Unit (BARU), Duke University, Room A110C, Erwin Mill Building, 2024 W. Main St, Durham, NC, 27708, USA. kk183@duke.edu.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: King
authors.affiliation: Division of Water, Climate, and the Environment, School of Earth Sciences, The Ohio State University, 275 Mendenhall Laboratory, 125th South Oval, Columbus, OH, USA. darrah.24@osu.edu.
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Darrah
authors.affiliation: Center for Geospatial Analytics, North Carolina State University, 5125 Jordan Hall, Campus Box 7106, Raleigh, NC, USA. esmoney@ncsu.edu.
authors.forename: Eric
authors.initials: E
authors.lastname: Money
authors.affiliation: Center for Geospatial Analytics, North Carolina State University, 5125 Jordan Hall, Campus Box 7106, Raleigh, NC, USA. rkmeente@ncsu.edu.
authors.forename: Ross
authors.initials: R
authors.lastname: Meentemeyer
authors.affiliation: Department of Biological Sciences, and Center for Human Health and the Environment, North Carolina State University, 850 Man Campus Dr, Campus Box 7633, Raleigh, NC, USA. rlmaguir@ncsu.edu.
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Maguire
authors.affiliation: Biological Sciences, University of North Carolina at Charlotte, 9201 University City Blvd, Charlotte, NC, USA. mnye@uncc.edu.
authors.forename: Monica D
authors.initials: MD
authors.lastname: Nye
authors.affiliation: Department of Community and Family Medicine, Duke University, 2200 Main St, Durham, NC, USA. lloyd.michener@dm.duke.edu.
authors.forename: Lloyd
authors.initials: L
authors.lastname: Michener
authors.affiliation: Department of Obstetrics and Gynecology, Duke University, 2608 Erwin Rd, Suite 210, Durham, NC, USA. amy.murtha@dm.duke.edu.
authors.forename: Amy P
authors.initials: AP
authors.lastname: Murtha
authors.affiliation: Department of Biological Sciences, and Center for Human Health and the Environment, North Carolina State University, 850 Man Campus Dr, Campus Box 7633, Raleigh, NC, USA. jirtle@geneimprint.com.
authors.forename: Randy
authors.initials: R
authors.lastname: Jirtle
authors.affiliation: Department of Obstetrics and Gynecology, Duke University, 2608 Erwin Rd, Suite 210, Durham, NC, USA. susan.murphy@dm.duke.edu.
authors.forename: Susan K
authors.initials: SK
authors.lastname: Murphy
authors.affiliation: Department of Nutrition, University of North Carolina, 101 Manning Dr, Chapel Hill, NC, USA. mmendez@email.unc.edu.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Mendez
authors.affiliation: Department of Soil Science, North Carolina State University, PO Box 7619, Raleigh, NC, USA. wayne_robarge@ncsu.edu.
authors.forename: Wayne
authors.initials: W
authors.lastname: Robarge
authors.affiliation: Nicholas School of the Environment, Duke University, 450 Research Dr, Durham, NC, USA. vengosh@duke.edu.
authors.forename: Avner
authors.initials: A
authors.lastname: Vengosh
authors.affiliation: Department of Biological Sciences, and Center for Human Health and the Environment, North Carolina State University, 850 Man Campus Dr, Campus Box 7633, Raleigh, NC, USA. choyo@ncsu.edu.
authors.forename: Cathrine
authors.initials: C
authors.lastname: Hoyo
mesh_terms: D000328:Adult; D001151:Arsenic / Q000097:blood; D002104:Cadmium / Q000097:blood; D005260:Female; D006801:Humans; D007854:Lead / Q000097:blood; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D008628:Mercury / Q000097:blood; D019216:Metals, Heavy / Q000097:blood*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood* / Q000453:epidemiology; D011295:Prenatal Care / Q000706:statistics & numerical data*; D011297:Prenatal Exposure Delayed Effects / Q000517:prevention & control*; D012424:Rural Population / Q000706:statistics & numerical data; D014481:United States / Q000453:epidemiology; D014505:Urban Population / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D019216:Metals, Heavy; D002104:Cadmium; D007854:Lead; D008628:Mercury; D001151:Arsenic