Portal de Periódicos da CAPES

Guest Editorial: Responding to Blood Lead Levels < 10 μg/dL

2008; National Institute of Environmental Health Sciences; Volume: 116; Issue: 2 Linguagem: Inglês

10.1289/ehp.10703

1552-9924

Mary Jean Brown, George G. Rhoads,

Trace Elements in Health

Vol. 116, No. 2 PerspectivesOpen AccessGuest Editorial: Responding to Blood Lead Levels < 10 μg/dL Mary Jean Brown George G. Rhoads Mary Jean Brown and George G. Rhoads Published:1 February 2008https://doi.org/10.1289/ehp.10703Cited by:9AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit Miranda et al. (2007) in the August issue and Jusko et al. (2008) in the present issue of Environmental Health Perspectives provide additional evidence of adverse health effects in children at blood lead levels (BLLs) < 10 μg/dL—the Centers for Disease Control and Prevention's (CDC) BLL of concern. A surprising feature of the new data in children with BLLs < 10 μg/dL is the steepness of the blood lead–IQ curve at these low levels. Nonlinear modeling conducted by Canfield et al. (2003) suggested a 7.4-point IQ effect (roughly one-half standard deviation) as lifetime average BLL went from 1 to 10 μg/dL—more than twice as strong a relationship as shown by most estimates at higher exposures (Treatment of Lead-exposed Children Trial Group 1998). It may reasonably be asked whether such a strong relationship is plausible, particularly as there are no directly relevant animal or in vitro studies that demonstrate a steeper slope for adverse effects of lead exposure at lower BLLs than observed at higher levels.The CDC's National Health and Nutrition Examination Survey (NHANES) data indicate that the entire population of U.S. children 1–5 years of age enjoyed a decline in geometric mean BLLs from about 15 μg/dL in the late 1970s to < 2 μg/dL in 2002 (CDC 2005a), but there is no agreement that IQs have increased by 7 points. Reading scores for 9-year-old children in the United States, tracked by the National Center for Education Statistics, show little change from 1980 to 1999, a period that would have corresponded to the years of greatest blood lead decline in the toddler years of the tested children (Perie and Moran 2005). Thus, the interpretation of the recent results may not be obvious. New studies using designs that exclude or control potential confounding by pica, which can indicate an underlying developmental delay, or by environmental hygiene, indicating more widespread lead contamination, would be especially helpful in assessing these low-level effects.In the past, the CDC has responded to reports of adverse health effects at BLLs below the level previously thought to cause harm, by lowering the BLL that defines a child as lead poisoned. However, in 2005, the CDC and its Advisory Committee on Childhood Lead Poisoning Prevention, after a review of the available evidence, determined that children with BLLs < 10 μg/dL should not be considered lead poisoned as the term is used in the clinical setting (CDC 2005b). In addition, the CDC found that a) no effective, feasible interventions to reduce BLLs in this range have been demonstrated; b) no threshold for adverse effects has been identified; and c) given current laboratory methods, risk for misclassification of children is high. Thus, the approach of arbitrarily defining a new, lower BLL of concern was rejected. This decision also is consistent with the recently released recommendations of the U.S. Preventive Services Task Force (2006) "against routine screening for elevated blood lead levels in asymptomatic children aged 1 to 5 years who are at average risk."Rather, the CDC recommends a multitiered approach that includes case management of children with BLLs > 10 μg/dL coupled with an increased focus on primary prevention through the control and elimination of lead in children's environments. The elements of this strategy include:State-based strategic plans to eliminate childhood lead poisoning through a systematic society-wide effort that includes legislative and enforcement efforts to control lead paint hazards, particularly in the highest-risk housing (CDC 2007)A partnership between the CDC, the Environmental Protection Agency, and the U.S. Department of Housing and Urban Development to enforce the Residential Lead-Based Paint Hazard Reduction Act (1992) particularly in housing where children have repeatedly been identified as having elevated BLLsElimination of lead in consumer products that are marketed to childrenRecommendations that regulatory agencies abandon the practice of using a BLL of 10 μg/dL as the threshold for enforcement activities.These strategies focus on primary prevention of lead exposure to children, an approach that is in agreement with the conclusions of Jusko and colleagues (2008) as expressed in their earlier report from the same cohort (Canfield et al. 2003).In 1990, the nation adopted an ambitious goal to eliminate BLLs > 10 μg/dL as a public health problem by 2010. Recent data indicate that this goal is in sight. However, studies such as those by Miranda et al. (2007) and Jusko et al. (2008) sound a cautionary note. For the foreseeable future, lead will continue to contaminate the environment. Therefore, even after the 2010 goal is achieved, primary prevention efforts must be maintained to ensure that lead sources in children's environments are controlled or eliminated before children are exposed and that surveillance systems are in place to ensure that these efforts are effective.Mary Jean BrownGeorge G. RhoadsTherefore, even after the 2010 goal is achieved, primary prevention efforts must be maintained to ensure that lead sources in children's environments are controlled or eliminated before children are exposed and that surveillance systems are in place to ensure that these efforts are effective.ReferencesCanfield RL, Henderson CR, Cory-Slechta DA, Cox C, Jusko TA, Lanphear BP. 2003. Intellectual impairment in children with blood lead concentrations below 10 μg per deciliter. New Engl J Med 348(16):1517-152612700371. Crossref, Medline, Google ScholarCDC (Centers for Disease Control and Prevention). 2005a. Blood lead levels in the United States, 1999–2002. MMWR 54:513-51615917736. Medline, Google ScholarCDC. 2005b. Preventing Lead Poisoning in Young ChildrenAtlanta, GACenters for Disease Control and Prevention. Google ScholarCDC. 2007. State and Local ProgramsAtlanta, GACenters for Disease Control and PreventionAvailable: http://www.cdc.gov/nceh/lead/grants/contacts/CLPPP%20Map.htm[accessed 7 January 2008]. Google ScholarJusko TA, Henderson CR, Lanphear BP, Cory-Slecta DA, Canfield RL. 2008. Blood lead concentration < 10 μg/dL and child intelligence at 6 years of age. Environ Health Perspect 116:243-24818288325. Link, Google ScholarMiranda ML, Kim D, Galeano MAO, Paul CJ, Hull AP, Morgan SP. 2007. The relationship between early childhood blood lead levels and performance on end-of-grade tests. Environ Health Perspect 115:1248-125317687455. Link, Google ScholarPerie M, Moran R. 2005. NAEP Trends in Academic Progress: Three Decades of Student Performance in Reading and Mathematics. NCES 2005-464. U.S. Department of Education Sciences, National Center for Education StatisticsWashington DCU.S. Government Printing Offic. Google ScholarResidential Lead-Based Paint Hazard Reduction Act. 1992. Public Law 102-550.Treatment of Lead-exposed Children Trial Group. 1998. The Treatment of Lead-exposed Children (TLC) Trial: design and recruitment for a study of the effect of oral chelation on growth and development of toddlers. Paediatr Perinatal Epidemiol 12:313-333. Crossref, Medline, Google ScholarU.S. Preventive Services Task Force. 2006. Screening for lead levels in childhood and pregnancyAvailable: www.ahrq.gov/clinic/uspstf/uspslead.htm[accessed 22 June 2007]. Google ScholarFiguresReferencesRelatedDetailsCited by Banner W and Kahn C (2014) Low blood lead level effects on intelligence: Can a dose–response curve be determined from the epidemiological data?, Clinical Toxicology, 10.3109/15563650.2013.876544, 52:2, (113-117), Online publication date: 1-Feb-2014. Kaufman A, Zhou X, Reynolds M, Kaufman N, Green G and Weiss L (2014) The possible societal impact of the decrease in U.S. blood lead levels on adult IQ, Environmental Research, 10.1016/j.envres.2014.04.015, 132, (413-420), Online publication date: 1-Jul-2014. Ragas A (2011) Trends and challenges in risk assessment of environmental contaminants, Journal of Integrative Environmental Sciences, 10.1080/1943815X.2011.597769, 8:3, (195-218), Online publication date: 1-Sep-2011. Glorennec P, Peyr C, Poupon J, Oulhote Y and Le Bot B (2010) Identifying Sources of Lead Exposure for Children, with Lead Concentrations and Isotope Ratios, Journal of Occupational and Environmental Hygiene, 10.1080/15459621003648281, 7:5, (253-260), Online publication date: 18-Mar-2010. Schell L, Denham M, Stark A, Parsons P and Schulte E (2009) Growth of infants' length, weight, head and arm circumferences in relation to low levels of blood lead measured serially, American Journal of Human Biology, 10.1002/ajhb.20842, 21:2, (180-187), Online publication date: 1-Mar-2009. Healey N (2009) Lead toxicity, vulnerable subpopulations and emergency preparedness, Radiation Protection Dosimetry, 10.1093/rpd/ncp068, 134:3-4, (143-151), Online publication date: 1-Jun-2009. Rothenberg S (2018) Blood Lead Levels in Children, Environmental Health Perspectives, 116:11, (A472-A472), Online publication date: 1-Nov-2008.Rhoads G and Brown M (2018) Blood Lead Levels: Rhoads and Brown Respond, Environmental Health Perspectives, 116:11, (A472-A473), Online publication date: 1-Nov-2008. Padilla M, Elobeid M, Ruden D and Allison D (2010) An Examination of the Association of Selected Toxic Metals with Total and Central Obesity Indices: NHANES 99-02, International Journal of Environmental Research and Public Health, 10.3390/ijerph7093332, 7:9, (3332-3347) Vol. 116, No. 2 February 2008Metrics About Article Metrics Publication History Originally published1 February 2008Published in print1 February 2008 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.