Lead Contamination in Flint — An Abject Failure to Protect Public Health — NEJM:
Perspective from The New England Journal of Medicine
by David C. Bellinger, PhD (Harvard Medical School)
We have the knowledge required to redress this social crime. We know where the lead is, how people are exposed, and how it damages health. What we lack is the political will to do what should be done....
The dangers of lead exposure have been recognized for millennia. In the first century a.d., Dioscorides observed in his De Materia Medica that “lead makes the mind give way.” The first industrial hygiene act passed in the colonies, in 1723, prohibited the use of lead in the apparatus used to distill rum, because “the strong liquors and spirits that are distilld through leaden heads or pipes are judged on good grounds to be unwholsom and hurtful.” More recently, large amounts of lead were used to boost the octane rating of gasoline and improve the performance of paint. One would be challenged to design a better strategy for maximizing population exposure to a poison than to have it emitted by a ubiquitous mobile source and to line the surfaces of dwellings with it.
The dramatic reduction over the past 40 years in blood lead levels in the U.S. population is rightly regarded as one of the cardinal public health success stories. It was achieved largely by phasing out lead as a gasoline additive and restricting the amount of lead permitted in paint. At the same time, 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.
Water doesn’t receive as much attention as paint as a route of lead exposure, but the use of lead in water-distribution systems goes back to the Romans. Indeed, our word “plumbing” derives from the Latin for lead, and lead poisoning is often called “plumbism.” The recent episode in Flint, Michigan, has brought the issue of lead in water into the public eye.
In 2014, solely as a cost-saving measure, the city began taking its water from the Flint River rather than Lake Huron. The corrosion-control treatments required by the Environmental Protection Agency’s Lead and Copper Rule1were, for some reason, discontinued. To make matters worse, the addition of ferric chloride to reduce the formation of trihalomethanes from organic matter increased the corrosivity of the Flint River water. The water reaching consumers was therefore 19 times as corrosive as it had been when the source was Lake Huron. The more corrosive water is, the more readily it can dissolve metals such as lead. So the lead concentration in Flint’s water began to rise. In six of nine city wards, the water in 20 to 32% of the homes had a lead concentration above 15 μg per liter, a concentration that triggers remedial action under the Lead and Copper Rule. The 90th percentile was 25 μg per liter, and in some samples the concentration exceeded 1000 μg per liter (www.FlintWaterStudy.org).