Epidemiologist Bruce Lanphear links lead levels to murder
SFU environmental-health expert Bruce Lanphear is no stranger to controversy. He readily admitted in a recent phone interview with the Georgia Straight that his investigations into the devastating effects of lead on the brain have made him extremely unpopular in certain circles. Industry officials, policymakers, and sometimes even other academics don’t want to hear what he has to say about the links between higher lead levels and higher rates of cardiovascular disease, interpersonal violence, and declining intellects.
“There have been times when essentially everybody would like to put me in the closet and lock the door,” Lanphear lamented.
But that hasn’t stopped him, and this week, Lanphear’s achievements were recognized when he was granted the Nora and Ted Sterling Prize in Support of Controversy. Established in 1993, the annual award honours a member of the SFU community whose work “provokes and/or contributes to the understanding of controversy”.
Lanphear was quick to point out that in industrialized countries such as Canada and the United States in recent years, there has been a 90-percent decline in average lead levels in blood. But that doesn’t mean the issue has been resolved, because, according to his research, there is no safe level—and the amount of lead in a modern person’s bloodstream vastly exceeds what was there many hundreds of years ago.
“In fact, the levels that you and I and our children experience today are somewhere higher than 100 times those levels experienced by our preindustrial ancestors,” he noted.
Health Canada states on its website that level levels of 10 to 15 micrograms per decilitre of blood “have been associated with adverse neurobehavioural and cognitive changes” in fetuses, infants, and children. At levels above 40 micrograms per decilitre, the body starts losing its capacity to produce red blood cells.
However, Lanphear said that even below the 10-microgram level, there are negative impacts on children’s cognitive abilities. For example, he said that when levels rise from one to 10 micrograms, there is an average drop in intelligence-quotient scores of six to seven points. Moving from 10 to 20 micrograms, the IQ reduction is about 2.5 points, on average.
“So the overall reduction is about three times greater, proportionately, at the lower levels, which sort of blows everything out of the water,” he stated.
That’s not all. He cited studies over the past 50 years linking higher lead levels in children to a higher likelihood of increased violence, including murder, in young adulthood. His research team examined this in more detail by looking at the relationship between higher lead levels and the structure and functioning of the brain. Using functional magnetic-resonance imaging, they determined that as children’s lead levels increased in their bloodstream, their prefrontal cortex was “diminished in volume”.
Dr. Stephen Kiraly, a Bowen Island psychiatrist, described the prefrontal cortex as “the command post and search engine of the brain” in his 2008 book Your Healthy Brain: A Personal & Family Guide to Staying Healthy & Living Longer. It is linked to forethought, planning, insight, self-reflection, self-knowledge, and impulse control.
Lanphear noted that antisocial behaviour, including criminal behaviour, and attention deficit hyperactivity disorder are the two major types of behaviour problems linked to a damaged prefrontal cortex. So if lead causes this part of the brain to shrink, this can have profound implications.
“The prefrontal cortex is what makes us most distinctly human,” he said. “It’s what distinguishes us from animals. So what we found is that widespread exposure to a toxin, even at low levels, can have an adverse effect on that part of the brain that really makes us distinctly human. It is really critical for surviving or thriving in an environment like we have today.”
He also pointed to links between high lead levels and heart disease. Traditionally, the medical profession has attributed many cardiovascular problems to lifestyle choices, but Lanphear emphasized that some of the factors causing these illnesses are beyond an individual’s ability to influence. “We haven’t, as a society, dealt with these environmental influences that people can’t control on their own,” he said.
Lanphear was one of the experts interviewed by UBC law professor Joel Bakan for his recent book, Childhood Under Siege: How Big Business Targets Children, about conflicts of interest in scientific research. Lanphear is quoted as saying that with federal agencies, including the U.S. Food and Drug Administration, “It’s not unusual to see up to 50 percent of an advisory committee that have some financial ties with industry”.
He’s pleased with the progress in eliminating leaded gasoline—it’s only being sold in about a half-dozen countries. There are still several countries that continue to allow the use of lead-based paints, which is the second major cause of lead exposure. “Once we eliminate leaded gasoline and lead-based paint, we’re really over halfway to eliminating lead poisoning worldwide,” Lanphear said. “So we really could begin to see the elimination of an environmental pollutant—lead—and it would have a tremendous impact on society.”
Follow Charlie Smith on Twitter at twitter.com/csmithstraight.