Guidelines for the Identification and Management of Lead Exposure

­­CHAPTER 1.INTRODUCTION KEY POINTS• Lead exposure remains a public health problem for certain groups of women of childbearing age and for the developing fetus and nursing infant. Prenatal lead exposure has knowninfluences on maternal health and infant birth and neurodevelopmental outcomes.• Bone lead stores are mobilized in pregnancy and lactation for women with prior leadexposure, which is a concern since lead released into maternal blood and breast milk canadversely affect the fetus or newborn.• Certain population subgroups of women at increased risk for exposure have been identified and may be highly exposed, particularly the following: workers in certain occupations;foreign-born recent immigrants; and those practicing certain behaviors associated withlead exposure, such as pica or renovation of older homes.• Identifying pregnant women with a history of lead poisoning or who are currently exposedto lead above background levels and preventing additional lead exposure can help preventadverse health outcomes in these children.Despite improvements in environmental policies and significant reductions in U.S. average population bloodlead levels, lead exposure remains a concern for pregnant and lactating women among certain populationsubgroups at increased risk for exposure. There is increasing awareness that unintended exposures to environmentalcontaminants, such as lead, adversely affect maternal and infant health, including the ability to becomepregnant, maintain a healthy pregnancy, and have a healthy baby. In the United States, women of childbearingage represent approximately 42% of the total population (American Community Survey 2004) and atany given time almost 9% are pregnant (Crocetti et al. 1990). In the 2003-2006 National Health and NutritionExamination Survey (NHANES) survey, the 95th percentile for blood lead levels among women aged 15-49 was2.4 micrograms per deciliter (µg/dL). As Figure 1-1 indicates, blood lead levels among women aged 15-49 havedropped substantially since the 1976-1980 NHANES. Recent NHANES estimates suggest that almost 1% ofwomen of childbearing age (15-49 years) have blood lead levels greater than or equal to 5 µg/dL (Centers forDisease Control and Prevention 2008, unpublished data).Lead exposure remains a public health problem for subpopulations of women of childbearing age and for thedeveloping fetus and nursing infant for several important reasons. First, prenatal lead exposure has knowninfluences on maternal health and infant birth and neurodevelopmental outcomes (Bellinger 2005). Researchfindings suggest that prenatal lead exposure can adversely affect maternal and child health across a widerange of maternal exposure levels. In addition, adverse effects of lead are being identified at lower levels of exposurethan previously recognized in both child and adult populations (Canfield et al. 2003; Jusko et al. 2008;Lanphear et al. 2005; Menke et al. 2006; Navas-Acien et al. 2007; Tellez-Rojo et al. 2006).Second, bone lead stores are mobilized during periods of increased bone turnover such as pregnancy and lactation.Over 90% of lead in the adult human body is stored in bone (Barry 1975; Barry and Mossman 1970), andmay result in redistribution of cumulative lead stores from bone into blood during periods of heightened boneturnover, such as pregnancy and lactation (Gulson et al. 2003; Roberts and Silbergeld 1995). Since bone leadstores persist for decades, women and their infants may be at risk for continued exposure long after exposureto external environmental sources has been terminated.1