Lessons From Flint: What Should Clinicians Do About Lead Now?

Linda Brookes, MSc

Disclosures

March 17, 2016

Lead in the News

Since the water crisis in Flint, Michigan, became national news, concern has been mounting that other US cities might be facing similar problems with increased levels of lead in tap water, and about the potentially serious health consequences of elevated blood lead levels (BLLs) in children. Outside Michigan, city and state officials and scientists have been reviewing test data and reexamining their own water sources; several have discovered water lead levels as high or even higher than those recorded in Flint, and children have been found with elevated BLLs.[1,2]

Figure 1. A child in Flint undergoing blood lead level testing. Image from Carlos Osorio/AP

Increasingly, reports have suggested that elevated lead levels in tap water may be a nationwide problem that has been underestimated and that the Flint crisis presents a wake-up call for family physicians and pediatricians, who have considered the dangers of lead toxicity in everyday life to be of mainly historical interest. It also raises the question about whether screening of BLLs in children is adequate (Figure 1).

Figure 2. Michael Weitzman, MD. Image courtesy of Wikimedia Commons

To discuss the medical implications of the Flint water crisis nationwide, Medscape spoke with Michael Weitzman, MD, professor in the departments of pediatrics, environmental medicine, and global public health at New York University (NYU) School of Medicine (Figure 2). As well as conducting more than 20 years of research into the neurotoxic effects of lead exposure on children, Dr Weitzman served in advisory capacities to Centers for Disease Control and Prevention (CDC), on its Advisory Committee on Childhood Lead Poisoning Prevention (1997-2002), and the Environmental Protection Agency (EPA) on its Clean Air Scientific Advisory Committee Lead Review Panel (2010-2013).

Lead Poisoning Decline

As Dr Weitzman pointed out, over the past half century, there have been profound changes in childhood lead poisoning in the United States and the developed world. "There has been a remarkable decrease in children's BLLs in the United States," he noted. Data from the 1976-1980 cycle of the National Health and Nutrition Examination Survey (NHANES) indicated that an estimated 88% of children aged 1-5 years had BLLs ≥ 10 μg/dL (mean, 15 μg/dL),[3] whereas by 2008-2010, the percentage of children with elevated BLLs had fallen to 0.8% and the mean BLL was 1.3 μg/dL.[4] "This is the consequence of a concerted series of public policies, such as the phasedown of lead from gasoline, which began in the 1970s; the final removal of lead in paint used for housing, which occurred in 1978; the ban on lead-containing solder (especially for use in canned and baby foods) that was passed in the 1990s; universal screening of children (up to 1997); heightened public awareness; and the passing of regulations requiring landlords to disclose any known lead paint hazards to prospective tenants."

As a result of this fall in BLLs, "it is now virtually unheard of for any pediatrician in the United States to have ever seen a child who has died of lead poisoning or a child who has had acute lead encephalopathy," Dr Weitzman said. "Acute lead encephalopathy is almost always associated with a BLL exceeding 100 µg/dL. The child has increased intracranial pressure and presents with coma and seizures and must be hospitalized and treated immediately. A very substantial percentage (70%-80%) of these children have profoundly delayed development," he explained. "Since the late 1960s/early 1970s, children's BLLs have come down so dramatically that the vast majority of children who have elevated BLLs nowadays are essentially asymptomatic, and it requires testing to identify those children or those who are symptomatic because of the elevated levels," he cautioned.

In parallel with the fall in BLLs, there has been a notable growth in the research literature showing the neurocognitive and behavioral benefits of increasingly lower levels of lead in children. "Some people say that this is one of the greatest pediatric public health success stories of the 20th century," Dr Weitzman said. "At the same time," he added, "the public health community, the research community, and large portions of the pediatric primary care community recognize that there are subtle but serious neurocognitive and neurobehavioral consequences of even the historically low BLLs that we are seeing now."

In 2005, Dr Weitzman chaired the CDC work group that reviewed the evidence for maintaining "BLL of concern" in children at 10 μg/dL.[5] "This was revisited by the CDC in 2012 because of extensive new literature showing significant lifelong health damage caused by lead levels between 5 and 10 μg/dL," he recalled. The CDC decided to use a reference range value based on the estimated 97.5 percentile of the BLL distribution among children aged 1-5 years that was calculated from two 4-year cycles of NHANES data.[6] "These are actually representative data, not based on pediatricians' reports," Dr Weitzman stresses.

On the basis of children aged 1-5 years in the top 2.5% of those tested, 5 μg/dL was set as the definition of an elevated BLL,[7] "although there is evidence that there is damage to children even below 5 μg/dL," Dr Weitzman noted. "We don't know whether every child with a BLL of 5 μg/dL has a problem, because when you look below 5 μg/dL, you still find problems," he cautions. "You have to set the cut-off point somewhere, but it is possible that any level of exposure damages any child with that level of exposure—just as there is nothing magical about a blood pressure of 140/90 mm Hg, which defines hypertension. There is no reason to believe that a blood pressure of 136/86 mm Hg isn't more dangerous than a blood pressure of 130/80 mm Hg, in the same way there is nothing magical about 5 μg/dL; it is just that you need cut-off points," Dr Weitzman explained.

"The CDC acknowledges that there is no threshold or safe level of lead exposure for children, but we don't want to terrify parents and we don't really have any interventions at these low levels," he added. At least 4 million US households today are estimated to include children who are being exposed to high levels of lead, and approximately half a million children aged 1-5 years have BLLs > 5 µg/dL.[7] "The CDC and the American Academy of Pediatrics (AAP) are profoundly concerned about these levels of lead," Dr Weitzman believes. "There is a dichotomy in that many practicing pediatricians think the battle is over, but the public health community and professional pediatric organizations do not believe that," he maintains.

The Flint Water Crisis

It is now well known that within 1 month after Flint's drinking water source was switched from the Detroit-supplied Lake Huron to Flint River water in April 2014, residents began to complain about the look, smell, and taste of their tap water (Figure 4).

Over the ensuing 18 months, protests about the quality of the water, including complaints about its corrosiveness from a local hospital and from the Flint General Motors plant, brought little response from city officials, and the Michigan Department of Environmental Quality continued to reassure the people of Flint that their drinking water was safe.[8] Officials also ignored an internal memo from an EPA expert highlighting the failure to use anticorrosive treatment in the Flint River water, which allowed lead from supply pipes to leach into the tap water.[8]

Figure 3. The Flint River. Image from Carlos Osorio/AP

In August, researchers from Virginia Polytechnic Institute and State University, popularly known as Virginia Tech, revealed data showing that 42% of Flint water samples tested had elevated lead levels, at > 5 parts per billion (ppb), and 20% had levels > 15 ppb—the threshold set by the EPA for remedial action.[9,10]

A turning point seemed to have been reached in September 2015, however, when local pediatrician Mona Hanna-Attisha, MD, MPH, and colleagues at the Hurley Children's Hospital and Michigan State University College of Human Medicine announced their finding of a strong correlation between high lead water levels in Flint and BLLs in Flint children.[11]

Figure 4. A Flint, Michigan, mother holding a bottle of tap water. Image from Joel Plummer/ZUMA/Alamy

Their study showed that between 2013 and 2015, the percentage of children in Flint aged < 5 years with elevated BLLs (≥ 5 μg/dL) increased from 2.4% to 4.9% (P<.05), compared with no significant change outside the city over the same period.[12] The highest BLLs recorded in Flint were 38 μg/dL.

"To me, 2.4% of children having an abnormal BLL is, from a public health point of view, a tragedy," Dr Weitzman commented. "We are talking about almost 1 in 20 children with BLLs that clearly have negative consequences in terms of decreases in IQ scores and increased neurocognitive problems (especially those tied to learning disabilities that increase the risk for lower reading scores, lower math scores, and school failure). Moreover, the evidence is clear that you diminish executive functioning with elevated lead levels."

After initially disputing the accuracy of Dr Hanna-Attish's data, Flint city officials switched the water supply back to the Lake Huron source in October 2015. According to the latest data from the Michigan Department of Health and Human Services (January-February 2016), the frequency of BLLs ≥ 5 μg/dL in children aged < 6 years in Flint, which was in decline before 2014, now stands at 1.9%.[13]

Figure 5. Dr Mona Hanna-Attisha. Image courtesy of Mona Hanna-Attisha, MD

In January 2016, Michigan State University and Hurley Children's Hospital announced that Dr Hanna-Attisha would lead a new pediatric public health initiative to address lead exposure in Flint and provide the tools and resources for the assessment, continued research and monitoring, and interventions necessary for improving children's health and development.[14,15] Federal prosecutors in Michigan are working with an investigative team that includes the Federal Bureau of Investigation, the US Postal Inspection Service, and the EPA's Office of Inspector General and Criminal Investigation Division to examine whether any laws were broken during the crisis.[16] In Congress, bipartisan legislation is pending to provide funding to help Flint replace its aging lead-contaminated pipes and make similar improvements and promote lead prevention programs in other states.[17]

Is Flint Unique?

Although other cities have claimed to have high-risk water sources, Dr Weitzman pointed out that for most children with elevated BLLs in the United States, lead paint and lead-contaminated house dust and soil are the primary routes of lead exposure.[18] In general, water contributes a very small percentage of the amount of lead to which children are currently exposed. However, Flint is not the only city that has had problems with lead in its water supply recently.

In 2000-2004, Washington, DC, experienced its own drinking water "lead crisis," when the percentage of BLLs ≥ 5 mg/dL increased above expected levels among people living in homes with leaded pipe water delivery.[19] A later study estimated that 859 DC children had BLLs ≥ 10 mg/dL in 2002 and 2003 because of exposure to high lead levels in water.[20] The EPA's final report concluded that the increased lead concentration in the water was caused by the failure to use an anticorrosive agent in the supply system when a different type of disinfectant was introduced in 2000.[21]

After the Washington crisis, researchers in other states began to suggest that the lead in their water supplies might also present a danger to child health and development and that the dangers of lead in tap water might have been underestimated.[22,23] The Flint water crisis also prompted articles in the press suggesting that, on the basis of the latest CDC data from 2014,[24] higher proportions of children have elevated BLLs in other cities and states, although not necessarily caused only by water contamination.[1,2,25] It was also noted that only 27 states reported childhood blood lead surveillance results to the CDC's national database for 2014, representing a small fraction of the infant population; this led the authors to conclude that an understanding about the true extent of childhood exposure to lead and its consequences must be lacking[2] (Figure 6).

Figure 6. Rates of blood lead testing among children aged < 72 months tested and confirmed BLL rates by year, 1997-2014. Centers for Disease Control and Prevention (CDC). http://www.cdc.gov/nceh/lead/data/Website_StateConfirmedByYear_1997_2014_01112016.pdf To view rates in your state, see the CDC's state surveillance data on blood lead levels.

Pediatricians at the Forefront

Dr Weitzman stresses that in such situations as the water crises in Flint and Washington, DC, it is the responsibility of the local health and housing departments, the water supply company, and the local branch of the EPA—and not pediatricians—to correct the levels of lead in the water supply. However, he echoes the AAP in emphasizing the leadership role that pediatricians can play in situations such as these.[26] AAP president Benard P. Dreyer, MD (NYU Langone Medical Center) commended Dr Hanna-Attisha in Flint for "forc[ing] authorities to recognize the risk to children and start[ing] a chain reaction of positive governmental involvement to treat this crisis as the disaster it is."[27] Dr Hanna-Attisha will be awarded the AAP President's Certificate for Outstanding Service for her advocacy and scientific study during the crisis.

"Pediatricians not only provide the care to individual children, but in many communities they are the most respected authority on child health and development. When pediatricians make a statement that something is dangerous, people listen up," Dr Weitzman reiterated. "In Flint, Dr Hanna-Attisha was clearly highly respected, and she figured out how to capture people's attention," he said. Flint residents were unable to get the same attention from city and state authorities, he added. "They were complaining about symptoms that had nothing to do with lead, such as rashes and hair loss. There is a sociologic term, 'blaming the victim'; and in this case, the children and their parents in Flint were the victims, and people denigrated them. Shame on us," he said.

More Screening Needed?

The Washington and Flint experiences have raised the question of whether pediatricians should be doing more screening of BLLs in children. Between 1991 and 1997, both the CDC and the AAP recommended universal blood lead screening of children aged 12-72 months to identify asymptomatic children with elevated BLLs. After it became apparent that the number of children at increased risk was declining and a national telephone survey indicated that most at-risk children were not being screened,[28] the CDC changed its recommendation to a more targeted approach.[29] Currently, screening for lead poisoning is recommended in children who are Medicaid-enrolled or -eligible, foreign-born, or identified as high-risk by the CDC location-specific recommendations or by a personal risk questionnaire.[6] The CDC recommended that states use their data to develop their own plans for screening and follow-up care for children at greatest risk. These now vary in every state and for each health department.

"The algorithms used by the medical and public health communities take account of poverty rates, age of housing, and the percentage of kids with elevated lead levels to drive the recommendations as to whether the children should be screened." Dr Weitzman explained. However, the Flint crisis has raised a new question about the role of lead in water in assessing risk in children, he believes. "When BLLs were higher, 10-20 years ago, lead in water was considered to make only a small contribution. But now that the level of concern is 5 μg/dL, it may make up a higher percentage of blood lead. When we were worried about kids with BLLs around 25 μg/dL and water made up 1%-2% of that, it did not make sense to put resources in to the water. That needs to be revisited now that we have concern about water levels," he suggested.

The AAP usually follows the CDC recommendations, Dr Weitzman noted. The Bright Futures guidelines, adopted by the AAP since 1998 and endorsed by the Health Resources and Services Administration, recommends that a clinical risk assessment for lead exposure be performed for infants (aged 6 and 9 months), with blood lead testing to follow if positive.[30] The assessment should include questions about Medicaid eligibility and living in housing built before 1978. The Bright Futures guidelines also recommend that children who are enrolled in Medicaid or living in high-risk areas as defined by the state or local health departments be screened for lead at age 12 and 24 months.

Objections to the abandonment of universal screening by the CDC were voiced immediately after publication of the 1997 recommendations.[29] Opponents of the measures called the CDC's decision a mistake and cited lead as the greatest environmental threat to children in the United States.[31] A recent call for a return to universal screening suggested that all children should be tested before they enter nursery school.[32] Whereas the definition of nursery school is unclear and could apply to children as young as 12 months or as old as 4 years, Dr Weitzman advocates for universal screening that begins at 1-2 years with targeted screening up to the age of 6 years, with risk identified through current screening surveys.

The usefulness of the lead risk assessment questionnaires has been questioned, with one study reporting that they performed little better than chance at predicting lead poisoning risk among children.[33] However, selective approaches have been shown to be more cost-effective than universal testing in populations with low prevalences of lead poisoning, Dr Weitzman noted. "For example, in such states as California or Nevada, where most housing is new, there is no lead-based paint in the homes; the communities are newer, so the water pipes are newer, and we don't have lots of kids with BLLs > 5 μg/dL," he pointed out.

Pediatricians have been accused of not being "overly supportive" of lead screening, failing to recognize the seriousness of elevated BLLs and reluctant to devote the time and resources required for screening.[31] Dr Weitzman is also concerned that current screening recommendations are not being widely followed. "Younger clinicians don't know about lead because they consider it an historic problem," he stated. In a study carried out with colleagues at the University of Rochester, the AAP, and the CDC, Dr Weitzman showed that only 76% of AAP member pediatric residents reported carrying out all recommended screening.[34] Screening practices appeared to vary by area of the country and practice setting.

Around the same time, a study of AAP members in California found widespread nonadherence to the CDC guidelines for universal blood lead testing of children, especially among pediatricians working in communities where the prevalence of lead poisoning might be expected to be low.[35] "Many pediatricians I have met are not excited about lead toxicity, perhaps because we have not been clear enough in voicing ongoing concern," Dr Weitzman admitted. "Perhaps the terrible experience in Flint, Michigan, will serve as a wake-up call that this epidemic is far from over," he said. The role of the AAP in raising awareness of this problem is crucial, he believes.

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