“Several of us wrote a letter to the editor of Scientific America (SA) in April soon after this article was first published. It wasn’t posted and, to my knowledge, never acknowledged. Moreover, they re-posted it [the article]. It appears that SA is publishing controversial, one-sided articles to drum up subscriptions. They are also doing more industry-funded articles. In other words, it needs to delete the term, “Scientific” from its name. This is another example of industry’s insidious influence on science.”
on Lead Safe America Foundation’s
public Facebook discussion group.]
Dr. Lanphear’s letter in response to the [(first) publication of the S.A. article (in collaboration with Drs. Lidsky, Schneider and Vernon):
April 5, 2016
To Ms. Mariette DiChristina, Editor, Scientific American
RE: “Flint’s Lead-Tainted Water May Not Cause Permanent Brain Damage,” by Ellen Ruppel Shell, March 24, 2016
We scientists and physicians with career-long involvement with childhood lead poisoning and its prevention write to express our concern about the March 24 article by Ellen Ruppel Shell on the effects of lead-tainted water on the brains of children in Flint, Michigan. We fear that selective quotations regarding the effects (or lack thereof) of low level lead toxicity will lead many readers to erroneously conclude that that there are no serious consequences from low level lead exposure. The Centers for Disease Control, the US Environmental Protection Agency, the World Health Organization and the American Academy of Pediatrics have all concluded that there is no safe level of lead in the blood of children. In the New England Journal of Medicine on the same day as the Shell article publication, Dr. David Bellinger, a pre-eminent researcher of health effects of lead writes:
“Because of research opportunities created by reductions in population exposures, the consensus view on how much lead is “too much” has also evolved. It is now established that there is no safe level of lead, particularly for children. The reference blood lead concentration for children set by the Centers for Disease Control and Prevention, 5 μg per deciliter, is meaningful only for risk stratification.”
What is ignored in the Shell article is that literally dozens of epidemiological studies of the effects of lead on child development — in concert with extensive experimental data from animal studies — have clearly established that lead at low dose levels is associated with alterations in brain structure, neurochemistry, gene expression patterns, and later behavioral and cognitive deficits. Failure to learn, special education placement and increased behavioral problems among school children with known low blood lead levels, including levels below 5 μg/dL, are documented in studies from Chicago, Providence, New York, Detroit, North Carolina and elsewhere.
There is, in fact, no other toxic chemical that has such a large body of data demonstrating biological plausibility, temporality (cause preceding effect), consistency and robustness of its neurotoxic properties at low doses.
To support her position that “…the lead levels in the water have not necessarily created blood lead levels that will permanently damage mental functions in children…” Shell presents a quote attributed to another pre-eminent researcher of health effects of lead in children, Dr. Kim Dietrich. According to Shell, Dr. Dietrich said “But after the water problem is remedied, the blood lead concentrations will fall back to background levels in six to 12 months.” It is true that if a child is immediately removed from the source of his or her lead exposure, blood lead levels will decrease over time, but blood lead levels are only an indicator of recent or ongoing exposure.
What Shell neglects to explain is that even after blood lead levels are decreased over time with no new exposures, the body burden of lead stored in our bones can continue to cause negative effects for decades. Shell also quotes Dr. Dietrich as saying, “There are very few studies done for very low levels of exposure.” This quote is surprising considering Dr. Dietrich’s extensive work on the effects of low level lead exposures on children’s intellectual functioning. Dr. Dietrich’s own research shows that blood lead levels below 5 micrograms per deciliter have been definitively linked with IQ deficits, academic problems and behavioral problems in children. For example, in one such paper, “We conclude that environmental lead exposure in children who have maximal blood lead levels < 7.5 μg/dL is associated with intellectual deficits.” (Environ Health Perspect 113:894–899 (2005)). In fact, “the lead-associated intellectual decrement for children with a maximal blood lead level < 7.5 μg/dL was significantly greater than that observed for those with a maximal blood lead level ≥ 7.5 μg/dL”. In another paper, the authors
concluded, “Deficits in cognitive and academic skills associated with lead exposure occur at blood lead concentrations lower than 5 μg/dL.” (Public Health Reports, 2000; 115, 521-529). Unfortunately, not only may there be no threshold for the adverse neurodevelopmental consequences of early exposure, these early lead-related impairments may persist and be difficult to reverse.
Shell asserts that only “some children” will be affected by the environmental catastrophe in Flint. Yes, parents whose child has been exposed to lead in Flint or elsewhere should not conclude that the child is necessarily doomed to a life of crime and poor academic performance. However, there is a direct relationship between childhood blood lead levels and the severity of resulting educational/behavioral problems. Due to each child’s own particular genetic makeup, not all children will be alike in their response to a stressor like lead, so we can speculate that developmental and behavior problems “may” not necessarily occur or be severe in nature. But can we say with any certainty, in the absence of measures of what a child’s full potential might have been, that the child is unaffected by an exposure to lead? In any case, whatever the subtle and variable impact for an individual child, there should no longer be any doubt that the population impact of low level lead exposure is substantial and consistent.
In a recent opinion piece in the New York Times (March 26, 2016), Dr. Mona Hanna-Attisha, the physician who first uncovered the elevated blood lead levels in Flint’s children wrote, in reference to potential cognitive and behavioral consequences of lead exposure on Flint’s children, “We can reduce the impact of these adversities, including lead exposure, when we wrap these children in evidence-based interventions to promote their development. These include maternal infant support and early literacy programs; universal preschool; school health services; nutrition programs; and primary medical care and mental health care.”
While the programs and initiatives suggested by Dr. Hanna-Attisha would certainly have a positive influence on the children of Flint as well as other children with a variety of adverse neurodevelopmental experiences, Shell suggests based on work in animal models that environmental enrichment alone can counter the detrimental effects of lead on neurodevelopment. This is an over-simplified interpretation of the animal literature (which has no human counterpart). It also ignores the animal literature that suggests even low level lead exposure could blunt the potential positive effects of enrichment programs by adversely affecting multiple brain systems involved in neuroplasticity, that is the brain’s natural ability to form new connections in order to learn and remember and compensate for injury or changes in one’s
environment. We all wish for the research that would make amelioration more than “hopeful” and “potential” but we don’t have it for humans. We genuinely hope that the Flint debacle will bring attention to this hugely important research deficit.
Two of us (BPL and JS), were troubled by our interviews with Ms. Shell. Dr. Schneider (not quoted in her article) was concerned by what he felt was her biased inquiry and pointed questions particularly regarding the issue of effects of environmental enrichment. Dr. Lanphear spent an hour talking with Ms. Shell about the distinction between individual and population impact of low-level toxicity and was quite troubled by Ms. Shell’s transparent attempt to force a specific quote that would serve the purpose of her preconceived bias about low-level lead toxicity. Ms. Shell’s beliefs on low-level toxicity obviously haven’t changed since she wrote an article for the Atlantic in 1995 entitled, “An Element of Doubt”, despite extensive research implicating low-level lead toxicity in IQ deficits, academic abilities, ADHD-related behaviors and other problem behaviors published over the past 20 years. While we appreciate the importance of skepticism in science, Ms. Shell’s interviewing style and apparent biased selection of quotes raises questions about her objectivity.
In short, in the midst of hedging words such as “may” and “hopeful” and “potential” and “not necessarily occur” and “permanent damage“ and “some children” the article gives the unfortunate impressions that low-level lead exposure may not be so bad as abundant scientific evidence suggests, and that we have both the proven science and wherewithal to mitigate the damage. Sadly, that is not the case. While we can and must do whatever possible to ameliorate the adverse consequences of low-level lead toxicity, the only solution is to prevent exposure in the first place.
Jay S. Schneider, Ph.D.
Professor-Pathology, Anatomy and Cell Biology Thomas Jefferson University
1020 Locust Street, 521 JAH
Philadelphia, PA 19107
Bruce P. Lanphear, MD, MPH
Professor of Children’s Environmental Health BC Children’s Hospital
Simon Fraser University
3415 Ash Street,
Vancouver, BC V5Z 3E5
Theodore I. Lidsky, PhD
Former Director (retired), Laboratory of Electrophysiology
New York State Institute for Basic Research in Developmental Disabilities
84 New Dorp Plaza, Suite 209
Staten Island, NY 10306
Thomas M. Vernon, MD
2134 Spring St.
Philadelphia, PA 19103