The public health, sociology and criminal justice literature has addressed the relationship among lead exposure, general behavior and school success in school age children.1- 4 Experts strongly recommend that children with a history of lead exposure receive additional support in school.5 Little of this discussion has taken place in the advanced practice nursing literature, perhaps minimizing the opportunity for the nurse practitioner to be identified as a resource and advocate for this aggregate of children. This article reviews the evidence about the association among early and/or chronic lead exposure, poor school behavior and poor school performance and discusses the role of the healthcare provider in screening children for lead exposure.
Factors such as IQ, hyperactivity and school behavior are intricately related to success in school. Recent research has shown that even after controlling for multiple variables, IQ declines as much as 7.4 points as blood lead levels (BLL) increase from 1 mcg/dL to 10 mcg/dL, with the steepest decline occurring at 3 mcg/dL and above.6 Specific deficits in math skills have been documented in children with low-level exposures to lead.7 Recent work in Detroit schools also demonstrates a clear association between low and moderate exposures to lead and poor academic achievement, using standardized achievement tests as a measure of overall academic performance.8
Behaviors such as hyperactivity, inattentiveness, restlessness, conduct disorders and aggression are associated with lead exposure.9 Lead may have chronic long-term behavioral effects as well as typical short-term effects; 7-year-olds who have had low-level lead exposures as preschoolers show significantly more diagnoses of ADHD, even after controlling for possible confounding effects of social environmental factors such as poverty and disadvantage.10
Research in Cincinnati has shown that arrest rates for violent and nonviolent offenses in early adulthood rise as the person's early childhood blood lead level increases. The rate of rise in arrests begins at blood lead levels as low as 5 mcg/dL, with a steady increase for each 5 mcg/dL increase in blood lead. This study examined the patient's childhood lead level and considered prenatal maternal blood lead levels. The same associations were found between arrests in early adulthood and documented prenatal blood lead levels.11
No level of lead is safe for children. The CDC recently revised its recommendations to include specific and continued follow-up of children with lead levels above 5 mcg/dL, rather than the previous standard level of clinical concern, 10 mcg/dL. The CDC now encourages attention to any identifiable BLL and recommends abandoning the term "level of concern."12
In neighborhoods with higher concentrations of poverty and disadvantage, the overall average BLLs in children exceed 5 mcg/dL5; this implies that many children have even higher BLLs. Also, recent work has noted that poor and minority children are less likely to be screened, even though BLL screening is a Medicaid standard.4 Children younger than 6 are the usual screening pool for lead, but only an estimated 1 in 7 is actually screened. For example, the number of unscreened children and adolescents estimated to be in jeopardy of having high lead levels in the authors' local community is large. Only 5,000 children with potential lead exposure were screened as of 2012, leaving up to 60,000 unscreened.13 Sadly, such a low level of screening is not unique to this community. Childhood lead testing is not necessarily a protocol uniformly followed by healthcare providers, and it may not be available to all populations. When screening does take place, children often are not provided with follow-up screening on a regular basis, nor with treatment/mitigation for identified lead exposure.7
Incidence and Prevalence
Nationally, the number of children screened for lead exposure is not only lower than expected, the rate of screening has declined steadily. More than 4.2 million children were tested in 2008 and 2009, but by 2011 (the most recent data available), the number of children tested had declined to 3.5 million.14
With these screening rates, a clear estimate of incidence and prevalence is difficult to obtain with clinical confidence. However, current estimates postulate a population of children with lead levels above 5 mcg/dL at between 540,000 and 900,000 children.15
Specific Population Concerns
As noted above, some behaviors associated with children with lead exposure are impulsivity and aggression. Aggressive and even impulsive behaviors may result in school actions including referrals, suspensions and expulsions. Serious school behaviors may result in "safe school violations," defined as a violation of school policies including behavioral issues, truancy, and violence.5 These violations may lead to referral to the juvenile justice system.
Because of the overlap of behavioral symptoms, it is important to consider that youth and adolescents referred to the juvenile justice system may be chronically exposed to lead. Indeed, a recent pilot study with a convenience sample of 110 school age children and adolescents showed that one-third (33%, N = 33) had BLL above 3.3 mcg/dL, with eight (7.2%) above 6 mcg/dL.
Also, 11.8% of the children and 2.7% of their parents reported problems in school. Beyond problems in school, those who additionally reported "trouble with the law" were significantly more likely to have a higher lead level.16 If BLLs can be identified in youth and adolescents, perhaps a diversion from the juvenile justice system could be sought. This intervention may allow healthcare follow-up and treatment, impacting the path of the youth's life.
Implications for Practice
Primary care clinicians are often approached by parents who are concerned about their child's difficulties in the classroom. Given the low rates of lead screening, it is reasonable to assume that many older children and adolescents may have had unidentified lead exposure. In addition to screening for ADD and ADHD, the possibility of chronic lead exposure should be considered. A child who has been screened as a toddler or preschooler may have moved to a different location with increased environmental risk, and re-screening may need to be considered.
Adolescent girls have the additional risk of potential pregnancy, which would expose the fetus to maternal BLL and increase the adolescent's risk for poor performance in school and risky, impulsive behaviors. Screening may be accomplished using point-of-care capillary blood samples, with confirmatory venous samples.
Since children with moderate to low lead levels are not candidates for chelation therapy, it is important to understand effective mitigation methods and to increase parental awareness of the efficacy of such measures.
Simple changes in diet can help mitigate moderate and low lead levels, which do not require chelation. Diets high in calcium and iron are particularly effective, as is a pattern of eating that allows for snacks between meals, since food decreases the gastric absorption of lead.17,18 Schools may or may not support such dietary patterns, particularly in higher grade levels, and children in schools that do not have nutritional objectives such as after school snacks or breakfast programs provide fewer opportunities for mitigating lead exposure through dietary intervention. However, collaboration with the school staff, including the school nurse, may allow individual dietary plans including nutritional snacks as an intervention for the child or adolescent with low or moderate BLL.
Home cleaning strategies such as damp mopping and dusting (rather than dry) and use of HEPA filters on vacuums are helpful, and are well described in CDC guidelines for reducing lead exposure. Frequent hand washing, encouraged for a multitude of primary prevention reasons, is also effective in minimizing exposure to environmental lead.
If exposure to lead is identified, the above mitigation measures should be implemented, and follow-up screening with consistent reinforcement of effective mitigation strategies should be part of the plan of care.
A Serious Risk
Lead exposure is a serious health risk for school age children, and also a serious risk to success in school. Long-term risks of lead exposure include demonstrable increases in seriously anti-social behavior and arrests. Nurse practitioners and physician assistants in primary care are in an ideal position to serve as advocates and health educators for affected children and families. With interdisciplinary support, lead exposure can be identified and addressed in school age children, leading to more success in the classroom and fewer negative consequences in early adult behavior.
Kathleen Ahonen and Marilynne Wood are faculty members at the University of Toledo College of Nursing in Ohio. Ahonen practices part time at the Monroe County Health Department. Morris Jenkins is dean of the College of Health and Human Services at Southeast Missouri State University. Bradene Moore is a lawyer who is a member of the Michigan Supreme Court staff.
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11. Wright, JP, et al. Association of Prenatal and Childhood Blood Lead Concentrations with Criminal Arrests in Early Adulthood. PLoS Med. 2008;5(5)e101.
12. Centers for Disease Control and Prevention. What do parents need to know to protect their children? http://www.cdc.gov/nceh/lead/ACCLPP/blood_lead_levels.htm
13.Ohio Department of Health. Lead Poisoning Prevention-Children, Data and Statistics.http://www.odh.ohio.gov/odhprograms/cfhs/lead-ch/leadch1.aspx
14. Centers for Disease Control and Prevention National Surveillance Data (1997 -2011).
National Chart of Children <72 months Tested and Confirmed Elevated Blood Lead Level Rates by Year. http://www.cdc.gov/nceh/lead/data/national.htm
15. Alexander C. Ohio Healthy Homes Update. Paper presented at Forum on Environmental Health, May 2013. Toledo, Ohio.
16. Ahonen K, et al. Practice recommendations for standards of care in lead screening for children and adolescents. Poster session presented at the 7th International Nurse Practitioners/Advanced Practice Nursing Network Conference, Aug. 20, 2012, London, England.
17. Ettinger AS, et al. Effect of calcium supplementation on blood lead levels in pregnancy: a randomized placebo-controlled trial. Environ Health Perspect. 2009;117(1):26-31.
18. Liu J, et al. Regular breakfast and blood lead levels among preschool children. Environ Health. 2011;10:28.