In 1970, following passage of the Clean Air Act, the City of El Paso sued ASARCO over its sulfur dioxide emissions. During the process of discovery, ASARCO submitted documentation of its emissions to the city for the first time. ASARCO's reports showed that, between 1969 and 1971, the company had emitted 1012 metric tons of lead, 508 metric tons of zinc, 11 metric tons of cadmium and one metric ton of arsenic (Landrigan, et al). On the basis of these documented emissions Bernard Rosenblum, Director of the El Paso City-County Health Department, estimated that 2700 persons between the ages of 1 and 19 would have blood lead levels at or above 40 micrograms per 100 milliliters—the safety standard for lead in blood at the time—and that residents within a four-mile radius of the smelter were likely to be the most affected.
Alarmed, Dr. Rosenblum contacted the Communicable Disease Center (now the Centers for Disease Control) in Atlanta, Georgia. The CDC sent Dr. Philip Landrigan and a team of researchers to investigate. Dr. Landrigan recalls that the National Academy of Sciences had just released a report minimizing the dangers of lead:
"It was well-known that certain smelters emitted lead, that it might be a problem for livestock living near smelters, but ... people didn’t have to worry ... lead from smelters had never been shown to be a health hazard. So that was the context that surrounded our initial trip to El Paso." (Interview with Dr. Philip Landrigan)
An initial study conducted by the El Paso City/County Health Department had sampled air, soil and dust for lead in a variety of locations. Dr. Landrigan’s team plotted the results in geographical relationship to the smelter. Although ASARCO argued that the lead was the result of gasoline emissions along Interstate 10, the chemical signature of the lead tied it to ASARCO's emissions; accordingly, the researchers concluded that the smelter was responsible for the lead contamination. Based on these initial results, the CDC team conducted a pilot study of blood lead levels in children attending a nursery school in Kern Place, a prosperous neighborhood located about a mile from ASARCO's smokestacks.
"What we found in our pilot test of these children from the preschool nursery was that about 3/4 of them had blood lead levels above 40 micrograms per deciliter. That immediately set off alarms, because even in the worst inner city neighborhoods ... we had never seen 3/4 of the children with blood lead levels above 40."
Dr. Landrigan and his associates set up a plan to sample blood lead levels in children within approximately four miles of the smelter. They drew concentric circles around the smelter and divided them into zones: Zone One was set at a radius of approximately one mile from the smelter. It included Smeltertown, a Mexican-American community located next to ASARCO and directly under the smokestacks. Zone Two was set at a radius of about 2.5 miles, and Zone Three was set at approximately four miles. Dr. Landrigan recalls that in Zone One the team “knocked on every door…Zone Two was every second door, and Zone Three…was every third or fourth door.” At each household blood samples were taken and soil, dust and paint samples collected. If pottery was used in cooking, the pottery was tested for lead content.
"What we found was really quite shocking. In Smeltertown about 70% of the children had blood-lead levels over 40 micrograms. In the rest of Zone One it was about 35%. In Zones 2 and 3 it was about 10% each."
The researchers now confronted another problem: there were no studies demonstrating that the lead levels they found could cause harm to children. The National Academy of Sciences study had asserted that lead from smelters was not harmful to human health.
"In those days not too much was known about the toxicity of lead in children. Pediatric lead poisoning of course had been known since the early years of the 20th century … But lead poisoning was understood as an all-or-none disease. Either a child got terribly sick from a high-dose ingestion, or it wasn’t an issue. People treated it almost as if it was a common cold; either you’re sick or you’re not sick, and there was nothing in between."
The CDC team was asked by Dr. Rosenblum to design further tests to determine whether children in El Paso were damaged by their exposure to ASARCO’s lead emissions.
Meanwhile, other interests were converging on the El Paso lead controversy. The El Paso Pediatric Society issued a bulletin stating, “there is no evidence that there is a lead intoxication problem outside of Smeltertown” (quoted in Shapleigh 19). ASARCO also commissioned its own study which was implemented by Dr. James McNeil, an El Paso pediatrician, and Dr. Potasnick, a psychologist from the El Paso School District. McNeil’s study, funded by the International Lead Zinc Research Association, a group connected to the metal industry, concluded that blood lead levels of 40 to 80 micrograms per deciliter were safe, provided a child received good nutrition. McNeil also insisted that the children’s elevated lead levels were based on exposure to lead-based paint, rather than ASARCO's emissions.*
In 1972 the Lead Surveillance Committee of the El Paso County Medical Society was formed. It included James McNeil, Bernard Rosenblum and Dr. Jorge Magaña, who would later become head of the City/County Health Department. The Committee took the position that further testing was unnecessary and "unjustified” (Shapleigh 19). They rejected a $50,000 CDC grant for Dr. Landrigan to continue his research. In 1973 they wrote the following letter to Dr. Landrigan:
I regret to inform you that our Board of Health unanimously voted to cancel the remaining portion of your study and in its place accept Dr. McNeil’s study from the International Lead Zinc Research Organization.
Dr. Landrigan recalls that the team had prepared a study design and returned to El Paso in the summer of 1973. After receiving the letter, he contacted the Texas state Attorney General, John Hill. When Hill concluded that there was no legal reason why the CDC should not continue with their study, the researchers went to work. They test children with high blood lead levels as well as a. control group of children with blood lead levels below 40.
"We found a significant difference between the two groups of children. The children who had blood lead levels over 40 had an average IQ on the performance scale of the Wexler Test that was about 7 points lower than the children who had the lower blood lead levels. This was a very statistically significant detriment in the kids’ IQ. We also found they had a much slower reaction time. We had a finger tapping test we had designed that counted how many taps a child could do in 10 seconds. And we found that the children with the elevated blood levels were distinctly slower than their peers on this test."
Dr. Landrigan’s research, and the results produced by the CDC team, contributed significantly to scientific knowledge about lead. It is now widely accepted that lead is toxic at levels as low as 5 micrograms per deciliter, and is particularly damaging to the developing brains of children.
* Dr. James McNeil Letter–Spanish version
Senator Eliot Shapleigh, Asarco in El Paso: September 2008
Interview with Dr. Philip Landrigan, September 2009, New York City, New York
Gerald Markowitz and David Rosner, Lead Wars: The Politics of Science and the Fate of America's Children, U of California Press, 2014.