LITERATURE REVIEW: OVERVIEW OF CHILDHOOD LEAD POISONING AND ITS HEALTH EFFECTS July 2019 Literature Review: Overview of Childhood Lead Poisoning and Its Health Effects INTRODUCTION* Lead poisoning is a preventable disease caused by exposure to common sources, such as lead-containing dust or lead-paint.1 The scientific community has documented lead’s toxic effects since the Greek physician Nicander of Colophon identified paralysis and saturnine colic as consequences of exposure.2 Benjamin Franklin noted in his 1786 letter to Benjamin Vaughn that “Plumbers, Glasiers, Painters” and others in trades involving lead suffered health consequences from their work.3 Historically, lead compounds have been widely used as paint pigments and agents in gasoline.4 Lead toxicity in children was first reported in Queensland5 in 1892 by Dr. John Lockhart Gibson, who described children with severe neurologic disease associated with exposure to deteriorating white lead paint.6 In the United States, blood lead levels (BLLs) in children have decreased dramatically over the past four decades. Still, many children live in homes with deteriorating lead-based paint, putting them at risk for lead-associated cognitive impairment and behavioral problems,7 among others. Prior to the mid-1950s, a significant percentage of house paint available to Americans was 50% lead. The allowable lead content of paint was lowered by the Consumer Product Safety Commission to 1.0 % in 1971, to 0.06% in 1977, and to 0.009% in 2009.8 Lead-based paint in pre-1978 housing is the most common and highly concentrated source of lead exposure for children. In 2002, Jacobs and colleagues assessed that “despite considerable progress, significant lead-based paint hazards remain prevalent, existing in 25% of all U.S. housing.”9 They also found that “2.7 million homes without lead-based paint had dust lead hazards,” and that even if lead-based paint hazards were not present in the home, they could be reintroduced into the environment through rehabilitation, maintenance, and repainting.10 From 2007 to 2010, approximately 2.6% of preschool children in the United States reported a blood lead concentration greater than or equal to 5 micrograms per deciliter (µg/dL) (≥50 ppb), which represents about 535,000 children 12 months to 5 years of age.11 This number was calculated using the National Health and Nutrition Examination Survey (NHANES), which collects data from interviews and physical examinations.12 Thus, this percentage only captures reported cases and does not reflect all lead poisoning cases in the United States. A 2017 study using the same NHANES data, in addition to information on underreporting and under- * Natalie Alvarado, MPH, authored this document under the supervision of Professor Emily A. Benfer. In addition, Virginia Morgan, MPH, contributed research to the literature review. Nga Bui, MPH and MSW candidate, authored the Appendix: Effects of Lead Poisoning by Blood Lead Level. The literature review was completed during the Spring 2019 semester in the Health Justice Advocacy Clinic at Columbia Law School and Mailman School of Public Health and finalized in July 2019. 1 Parsons and McIntosh, Human Exposure to Lead and New Evidence of Adverse Health Effects: Implications for Analytical Measurements, (International Centre for Diffraction Data, 2010), 289. 2 Riva, Michele Agusto, et al, (Safety and Health at Work, 2012), 11-6. 3 Franklin, Benjamin edited by Goodman, N. G. The Ingenious Dr. Franklin: Selected Scientific Letters of Benjamin Franklin. Philadelphia: University of Pennsylvania Press (1931), 31-32. 4 Parsons and McIntosh, Human Exposure, 289. 5 Rosner, David et al. J. Lockhart Gibson and the Discovery of the Impact of Lead Pigments on Children's Health: A Review of a Century of Knowledge, Public Health Reports (2005), 296-300. 6 Bennett et al., Lead Poisoning: What's New About an Old Problem? (Contemporary Pediatrics 2015), 15. 7 American Academy of Pediatrics Council on Environmental Health, Prevention of Childhood Lead Toxicity. (Pediatrics, 2016), 4. 8 Agency for Toxic Substances, Case Studies in Environmental Medicine, 59 https://www.atsdr.cdc.gov/csem/lead/docs/CSEM-Lead_toxicity_508.pdf 9 Jacobs, David E. et al, The Prevalence of Lead-Based Paint Hazards in U.S. Housing, (Environmental Health Perspectives, 2002), A603-A604. 10 Jacobs, et al, The Prevalence of, A603-A604. 11 Centers for Disease Control, Blood Lead Levels in Children Aged 1–5 Years — United States, 1999–2010, (Morbidity and Mortality Weekly Report, April 2013), Table 1. 12 Centers for Disease Control National Center for Health Statistics, National Health and Nutrition Examination Survey Overview, CS269889-A. 1 Literature Review: Overview of Childhood Lead Poisoning and Its Health Effects testing, estimates there are approximately 1.2 million cases of elevated blood lead level (EBLL) among children between 12 months and 5 years of age.13 It is recognized by the Centers for Disease Control and Prevention (CDC), among others, that no BLL is free of adverse health risks and no safe level of blood lead has been identified.14 In recognition of this, the CDC adopted a “reference value” of 5 µg/dL in 2012.15 The CDC plans to continue updating the reference value every four years using the two most recent NHANES surveys.16 The Mayo Clinic recommends removing the source of the lead hazard from a child’s environment once an EBLL has been identified.17 In severe cases, such as where the EBLL exceeds 45 µg/dL, children may be referred to chelation therapy options, which are administered orally or through injection. Chelation works through the binding of the administered medication to the lead compounds in the body, resulting in the lead being excreted through urine.18 However, as noted by the American Academy of Pediatrics (AAP), “Primary prevention of lead exposure is now widely recognized as the optimal strategy because of the irreversible effects of low-level lead toxicity.”19 LEAD EXPOSURE Ingestion of lead-contaminated house dust, residential soil, and water are major pathways for lead toxicity.20 Other sources such as drinking water, ceramics, toys, children’s jewelry, imported candy and its candy wrappers, home and folk remedies, and cosmetics can also pose risks.21 In the United States, lead-based paint is a primary source of exposure to lead in a child’s environment.22 Lead may be released from lead-based paint if the paint is disturbed, deteriorated, or subject to friction or impact. Situations that can cause lead exposure include disturbing paint during renovation, paint that is disturbed from the everyday use of windows, doors and porches; and paint that is chalking, chipping, or peeling. 23 Lead-based paint was banned in 1978, increasing the likelihood that units built before that time contain possible lead-based paint hazards. According to Jacobs and colleagues, “Housing built before 1960 had five to eight times the prevalence of hazards compared with units built between 1960 and 1978.”24 Jacobs and colleagues also assessed that while only 16% of housing in the South and West regions of the 13 Roberts, Eric M., et al, Assessing Child Lead Poisoning Case Ascertainment in the US, 1999–2010, Pediatrics May 2017, 139 (5) e20164266; DOI: 10.1542/peds.2016-4266 14 Centers for Disease Control and Prevention, Childhood Lead Poisoning Prevention Program https://www.cdc.gov/nceh/lead/default.htm; see also Green and Healthy Homes Initiative, Home & Health: Lead, (GreenandHealthyHomes.org, 2019). 15 The reference value was adopted in May 2012, upon accepting the recommendations of its Advisory Committee on Childhood Lead Poisoning Prevention (ACCLPP). Prior to 2012, the CDC defined BLLs greater than or equal to 10 µg/dL as the standard "level of concern" for children between 1- to 5-years-of-age. Centers for Disease Control, Response to Advisory Committee on Childhood Lead Poisoning Prevention Recommendations in “Low Level Lead Exposure Harms Children: A Renewed Call of Primary Prevention, 2012. 16Centers for Disease Control and Prevention, What Do Parents Need to Know to Protect Their Children?, 2017. The current reference level is based on NHANES data of blood lead distribution in children from 2007-2008 and 2009-2010. 17 Mayo Clinic, Lead Poisoning, (MayoClinic.org, 2019). 18 Graziano JH. Role of 2,3-dimercaptosuccinic acid in the treatment of heavy metal poisoning. Med. Tox.;1:155–162 (1986). 19 American Academy of Pediatrics, Prevention of , 4. 20 American Academy of Pediatrics, Prevention of, 5. 21 US Department of Housing and Urban Development, (Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing, 2012), 1-8. 22 Agency for Toxic Substances and Disease Registry, Registry Case Studies in Environmental Medicine (CSEM) Lead Toxicity, Course WB2832, (2017), 20. 23 Agency for Toxic Substances, Registry Case Studies in Environmental Medicine, 36. 24 Jacobs, David E. et al, The Prevalence of Lead-Based Paint Hazards in U.S. Housing, (Environmental Health Perspectives, 2002), A601-A602. 2 Literature Review: Overview of Childhood Lead Poisoning and Its Health Effects country has lead-based paint hazards, hazards were found in approximately 36% of the housing in the Northeast and Midwest.25 While the oldest housing stock and therefore the greatest number of housing hazards are found in the Northeast and Midwest, the greatest numbers based on prevalence are from the South.26 Lanphear and colleagues found that children who lived in rental housing were at increased risk for higher blood lead concentration.27 They also found that 33% percent of rental housing was in poor condition compared with 13% of owner-occupied housing.28 According to the American Community Survey, 53.37% of housing stock in the United States was built before 1980, and 27.47% was built before 1960.29 New York, Rhode Island, Massachusetts, Connecticut, and Pennsylvania have the oldest housing stock in both of these categories.