e., irritability, dizziness, stomach pains, constipation, vomiting, muscle weakness, and lack of appetite) (Kessel & O'Connor, 1997).
The results of a study by Dolinoy and her colleagues notes that healthcare professionals have long recognized the threats represented by severe lead poisoning; however, since the late 1970s, there has been a growing body of research that indicates that lead also causes asymptomatic effects at levels far below thresholds previously considered safe. According to this authors, "The adverse effects of lead, including learning and behavioral disorders (e.g., attention deficit disorder and attention deficit hyperactivity disorder), hearing impairment, decreased intelligence quotient, and decreased attention span, are particularly harmful in children and often become apparent during puberty -- long after exposure has caused irreversible impacts" (Dolinoy et al., 2002, p. 947). In response, the Centers for Disease Control and Prevention have incrementally lowered the threshold for lead levels regarded as dangerous in children by fully 88% (from 60 to 10 [micro]g/dL) over the past 40 years; in addition, more recent investigations have found that cognitive deficits may occur at blood lead levels as low as 5 [micro]g/dL (Dolinoy et al., 2002).
Generally speaking, young people that have been lead poisoned to not present with any specific set of symptoms that identify a child as lead poisoned; possible neuropsychological symptoms vary from individual to individual, but the change in intelligence appears to be fairly consistent throughout a number of studies (Kessel & O'Connor, 1997). According to Barbosa, Tanus-Santos, Gerlach, and Parsons (2005), lead concentration in whole blood (BPb) is the most popular biomarker used to monitor lead exposure. For this purpose, the U.S. Centers for Disease Control and Prevention and the World Health Organization both define a BPb of 10 [micro]g/dL (0.48 [micro]mol/L) as being the threshold of concern for lead poisoning among young children; recent studies, though, have identified the potential for adverse health effects, including intellectual impairment in young children, at BPb levels < 10 [micro]g/dL, indicating that there is no safe level of exposure (Barbosa et al., 2005).
Likewise, a study by Fahs and his associates (2002) suggests that there is no safe level of exposure to lead. These researchers determined that the mean blood level of lead in the birth cohort of children age 5 years was reported in 1997 to be 2.7 [micro] g/dL; at that time, the estimated number of 5-year-old children in the United States was 1,960,200 boys and 1,869,800 girls (Fahs et al., 2002). According to these authors, "At this age, there is no significant difference between boys and girls in blood lead level. Application here of an IQ reduction of 0.25 IQ points/[micro] g/dL assumes implicitly that there is no threshold blood lead level below which cognitive effects are not seen" (Fahs et al., 2002, p. 721). The authors conclude that this assumption appears reasonable because cognitive deficits have been associated with all ranges of blood lead concentration studied, and no evidence of a threshold has been identified to date (Fahs et al., 2002).
In their study, Associations among Lead Dose Biomarkers, Uric Acid and Renal Function in Korean Lead Workers," Ahn and his colleagues report that gout has been common among lead-poisoned individuals; in recent years, though, links between various measures of lead dose and serum uric acid (urate) levels have also been reported in studies of occupationally exposed populations as well as in general population studies (Ahn et al., 2005). According to these authors, "These associations are present at much lower lead doses than those associated with gout in historical lead poisoning. Lead exposure also increases the risk for adverse renal outcomes. Lead has been reported to cause nephrotoxicity by several mechanisms, although it is not known which of these is the predominant pathway" (p. 36).
Recommendations to Eliminate Lead Poisoning as a Public Health Hazard.
By any measure, complex problems require complex solutions and the elimination of sources of lead poisoning as a public health hazard at home and abroad is no different. According to Dolinoy, Miranda, and Overstreet (2002), "Environmental threats to children's health -- especially low-level lead exposure -- are complex and multifaceted; consequently, mitigation of these threats has proven costly and insufficient and has produced economic and racial disparities in exposure among populations" (p. 947). Fortunately, a virtual consensus emerged from the literature review that suggests community education initiatives represent one of the best front-line approaches, particularly in developing nations although the same types of programs have proven effective in urban U.S. settings as well. For example, "Providing increased awareness is a tool to fight lead poisoning" (Kessel & O'Connor, 1997, p. 2). To this end, in response to the growing need for more public education, the Environmental Protection Agency and the Department of Housing and Urban Development jointly promulgated a regulation in March 1996 that provided for disclosure of possible hazards in lead-based paint at the time when any home is sold or rented in the United States; the rule implemented section 1018 of the Residential Lead-Based Paint Hazard Reduction Act of 1992, which was designed to protect families from exposure to lead from paint, dust and soil (Goldman, 1997).
In fact, while most researchers routinely call for the need for additional studies in a given area, some experts are suggesting that although additional studies are needed concerning the specific operation of lead in the human body, the scientific community already knows everything that needs to be known to eliminate this threat right now: "The knowledge that currently exists in the scientific community about the sources and pathways of lead exposure and about possible ways of preventing the ensuing poisoning is sufficient to facilitate the development of programs that should permanently eradicate this disease" (Dugbatey et al., 1995, p. 7). The authors caution, though, that because the sources and pathways of childhood lead poisoning are attributable to the constellation of community and individual behaviors and activities, a well-coordinated and multi-sectoral program planning for such interventions is imperative (Dugbatey et al., 1995). Furthermore, according to Croskey and her associates, there is an abundance of valuable educational materials for use in addressing the dangers associated with lead poisoning: "A host of traditional educational materials are available in the form of publications, videos, slides, and mass media endeavors. The key problem seems to be that the people for whom these materials are intended do not use them effectively" (Croskey et al., 2005, p. 15).
According to Dugbatey and his colleagues, St. Louis, Missouri has employed various community-based lead poison prevention initiatives for the past quarter century, but some recent changes in direction have improved the effectiveness of these programs. "Community-lead education efforts have traditionally been directed primarily at parents or other caregivers on behalf of children, while interventions with direct focus on the child have received less attention" (p. 7). The educational initiative developed by these researchers was based on the premise that children should be the primary recipients of lead education, and that the children's caregivers play a supportive role in this endeavor and emphasize that even preschool children are capable of learning, given the right kind of experience and incentive (Dugbatey et al., 1995). A follow-up study 10 years later by this author and others showed that efforts by the City of St. Louis's Childhood Lead Poisoning Prevention Program have focused exclusively on the identification of lead-poisoned children and their lead-contaminated environments. "Educational efforts," Croskey and her colleagues advise, "in the form of pamphlets and personal communications, have been provided to families with lead-poisoned children. This strategy, along with the elimination of lead in paint and gasoline, has been effective in reducing extreme levels of childhood lead poisoning" (Croskey, Dugbatey, Evans, Narayan & Osamudiamen, 2005, p. 15). Unfortunately, while much has been learned about lead poisoning and how it affects the human body in recent years, policymakers, public health officials, child advocates, and others continue to lack the appropriate infrastructure to adequately evaluate children's risk and exposure potential across a broad range of risks; based on this inability to identify where the highest risk of exposure exists, children's environmental health programs remain mitigative rather than preventive (Dolinoy et al., 2002). More importantly, though, researchers have found that even the most carefully designed educational initiatives have failed to significantly reduce the incidence of lead poisoning among inner city children, due in large part to the impoverished conditions in which these families live where they are confronted with higher survival priorities on a daily basis (Croskey et al., 2005).
Summary and Conclusions
Lead has been used by mankind for centuries, but the dangers associated with its use have only been identified fairly recently. The research showed that in spite of some progress in recent years, lead poisoning represents one of the leading preventable public health threats for young people in the United States and abroad today. The research showed that there are no safe levels of lead exposure for children, and lead levels…