Getting the Lead Out
Fifteen years after being effectively removed from the U.S. market, the prolific danger of leaded gasoline becomes clearer.
Think lead poisoning and you probably imagine dilapidated houses where babies and toddlers munch on flaked-off paint chips and inhale paint dust. Indeed, America's lead paint problem is real and damaging, but the history of another, somewhat forgotten source of lead-gasoline—turns out to be alive—and not well.
Leaded gasoline, created to eliminate the knocking sound inside engines that can occur when fuel combusts too quickly, was sold in the United States for roughly seven decades, from the 1920s until a 10-year phase-out ended in 1996.
Even at low levels, lead has been associated with serious health problems, including brain damage, learning and behavioral problems—and even criminality.
Blood tests performed during the period when lead-laced fuel was en vogue were often contaminated and therefore unreliable, making it impossible to know just how much of the lead children in that period took in came from gasoline as opposed to lead ingested from other sources. However, the effects of the fuel ban appear clear: Federal statistics show that nearly 78 percent of children had elevated blood lead levels in 1976, compared with just more than 4 percent in 1994.
Recently, a team of Case Western Reserve University scientists revealed just how big a role leaded gas played in childrens' consumption of the toxic metal.
It was gas—not paint or soldered food cans—that they say was responsible for two-thirds of children's uptake of lead in the latter two-thirds of the 20th century.
The finding not only reinforces the continuing danger in the 10 countries that still use leaded fuel, but also raises questions about the health of adults whose childhood was marred by lead spewed from tailpipes.
A History of Finger-Pointing
"There had been tons of reports showing a correlation between the drop in atmospheric lead and the lead in children's blood," says Norman Robbins, MD, an emeritus neuroscience professor at Case Western Reserve, who spearheaded the research. "So it was extremely clear to us that atmospheric lead was affecting levels of leads in children very, very strongly."
For decades, the lead paint and leaded gas industries have blamed each other for lead poisoning. What's more, industry scientists in the early days of leaded gasoline suggested that the human body naturally harbored lead, so high levels from the product shouldn't be of concern, according to Jamie Lincoln Kitman's award-winning exposé of the industry published in The Nation in 2000.
"This historical debate over liability and responsibility goes back 45 years," says David Rosner, PhD, co-author of the book Deceit and Denial, The Deadly Politics of Industrial Pollution, a history of environmental polluters. "Both the paint and lead industries are polluting the environment and causing lower IQs and have gotten out of it by pointing fingers at the other source."
Kitman says the debate goes back even further. From the time the first leaded gas was pumped at a Dayton, Ohio, station in the 1920s, he says, the automotive industry has battled with government health officials over its safety.
Thomas Midgley, an ambitious engineer who zeroed in on tetraethyl lead (TEL), an ingredient in leaded gasoline, as an anti-knock agent, went to great lengths to prove it was harmless, despite becoming living proof of its dangers. Midgley developed lead poisoning in 1923, but for more than a decade after would continue to demonstrate TEL's "safety" in public appearances by washing his hands in it.
"He was a type of mad scientist," Kitman says, adding that early on, many in the lead and automotive industries became so invested in TEL they made outlandish claims for it. "As they became accepted, they sort of started to believe," he says.
Robbins says that after decades of back-and-forth, he and his team decided to dig in and settle the score once and for all.
Putting the Debate to Rest
Professor of Dental Medicine James Lalumandier, DDS, and Richard Shulze, DDS, then a Case Western Reserve dental student, worked with collaborators at Northern Arizona University to provide, prepare and measure lead in the teeth of 124 Cleveland adults, most of whom grew up in inner-city neighborhoods.
Lalumandier says their teeth acted as a kind of historical record of exposure, as certain molars develop between infancy and age 8, which is when lead is likely to do permanent damage to a child's developing nervous system.
The researchers studied teeth that formed between 1936 and 1993 and had been extracted for dental purposes. Most were from African American patients because, the researchers say, lead poisoning is generally associated with poverty, and black children growing up in the 1960s and '70s were more likely to be lower-income, live near heavy traffic in homes with lead paint and be at an increased risk because of nutritional deficiencies.
Analysis by graduate student Zhong-Fa Zhang and statistics professor Jiayang Sun revealed the gravity of Clevelanders' exposure.
Their research, which was published in the June issue of the journal Science of the Total Environment, shows the amount of lead stored in teeth mirrored the use of TEL. The highest levels of lead ingestion occurred in the teeth of Clevelanders who were children growing up between 1960 and 1975-when use of the fuel was at its peak.
The team reported that, by extrapolation, the average blood lead level when TEL usage was at its highest was around 48 micro-grams of lead per deciliter. That far exceeds the modern federal threshold for elevated blood lead levels of 10 micrograms per deciliter. Many cities, including Cleveland, have set an even more rigorous standard, with 5 micrograms per deciliter as the cutoff.
"Forty-eight micrograms per deciliter would today be considered a medical emergency," says Stuart Greenberg, a 1966 alumnus of Adelbert College, now executive director of the Cleveland nonprofit organization Environmental Health Watch.
Effects Felt Around the World
According to the Centers for Disease Control and Prevention, 250,000 U.S. children still have elevated blood lead levels. The problem is likely to be an even larger issue overseas, where some developing countries continue to rely on leaded gasoline to power cars and other equipment.
"This is a wakeup call for them to stop using leaded gas as soon as possible," Lalumandier says.
Rob de Jong, head of the United Nations Environmental Program's transport unit, says that as much as 90 percent of lead uptake in developing countries has been blamed on TEL. The countries believed to still use leaded gas are Afghanistan, Algeria, Egypt, Iraq, North Korea and Yemen. Bosnia-Herzegovina, Montenegro, Myanmar and Serbia have said they plan to or hope to stop using leaded gas by early 2011.
Only one company remains that produces TEL. In March, that company agreed to pay $40.2 million after the Securities and Exchange Commission charged it with bribing Indonesian and Iraqi officials to keep buying TEL. The company neither admitted nor denied the charges in agreeing to the fine.
On the Home Front
Cleveland has consistently logged among the highest rates of lead poisoning in the country because of aging housing, traffic and proximity to industries that used the metal. As of 2008, some 3,298 children in the city had lead poisoning, based on the city's strict 5 micrograms per deciliter cutoff.
"No doubt a substantial proportion of Cleveland's population has suffered because of it, and the community has suffered because of that," says Greenberg, of the Cleveland environmental nonprofit.
The problem, Robbins says, is that many people with lead-related health problems are unaware of their source. In fact, many Cleveland residents and others who grew up in parts of the country with heavy traffic in a time where leaded gas was unregulated have suffered health consequences from atmospheric lead they may not know about. And women who were exposed to lead in childhood may have stored it in their bones and passed it along to their children, says Shulze, who is now in private practice.
This October, Robbins presented the group's findings to the Greater Cleveland Lead Advisory Council. Possible public health responses could include testing of adults and educational or behavioral training for people whose health was compromised by lead, particularly those exposed during the peak years of TEL usage, he says.
For now, the Cleveland Department of Public Health's lead poisoning program focuses on getting children tested and remediating homes with lead paint. No determination, though, has been made about whether the study indicates the need for expanded soil cleanup, says Matt Carroll, a department spokesman.
"Environmental impacts on adults would be of interest," he says, "but we're very much laser-focused on young children."
Robbins says the public may have a responsibility to widen that focus.
"If we're correct that the levels they were facing at the peak were 48 micrograms per deciliter, that blood level is associated with lots of problems," he explains. "So it's not just a guess they would have problems—it's highly likely. We kind of owe it to them to help."