Adult Exposure to Lead

“Children in approximately 4 million households in the United States are being exposed to high levels of lead.” As I discuss in my video The Effects of Low-Level Lead Exposure in Adults, “Despite the dramatic decline in children’s blood-lead concentrations over the decades, lead toxicity remains a major public health problem”—and not just for children. Yes, lead is “a devastating neurotoxin,” with learning disabilities and attention deficits in children beginning around blood lead levels of 10 mg/dL, which is when you start seeing high blood pressure and nerve damage in adults, as you can see at 0:41 in my video. But, the blood levels in American adults these days are down around 1 mg/dL, not 10 mg/dL, unless you work or play in an indoor firing range, where the lead levels in the air are so high that more than half of recreational target shooters have levels over 10 mg/dL or even 25 mg/dL.

In fact, even open-air outdoor ranges can be a problem. Spending just two days a month at such a range may quadruple blood lead levels and push them up into the danger zone. What if you don’t use firearms yourself but live in a house with someone who does? The lead levels can be so high that the Centers for Disease Control and Prevention advises those who go to shooting ranges to take “measures to prevent take-home exposure including showering and changing into clean clothes after shooting…, storing clean clothes in a separate bin from contaminated clothing, laundering of non disposable outer protective clothing…and leaving at the range shoes worn inside the firing range,” among other actions. Even if none of that applies and your blood levels are under 10 mg/dL, there is still some evidence of increased risk of hand tremors, high blood pressure, kidney damage, and other issues, as you can see at 1:44 in my video. But what if you’re down around a blood lead level of 1 mg/dL, like most people?

“Blood lead levels in the range currently considered acceptable are associated with increased prevalence of gout,” a painful arthritis. In fact, researchers found that blood levels as low as approximately 1.2 mg/dL, which is close to the current American average, can be associated with increased prevalence of gout. So, this means that “very low levels of lead may still be associated with health risks,” suggesting “there is no such thing as a ‘safe’ level of exposure to lead.”

Where is the lead even coming from? Lead only circulates in the body for about a month, so if you have lead in your bloodstream, it’s from some ongoing exposure. Most adults don’t eat peeling paint chips, though, and autos aren’t fueled by leaded gas anymore. There are specific foods, supplements, and cosmetics that are contaminated with lead (and I have videos on all those topics), but for most adults, the source of ongoing lead exposure is from our own skeleton. I just mentioned that lead only circulates in the body for about a month. Well, where does it go after that? It can get deposited in our bones. “More than 90% of the total body lead content resides in the bone, where the half-life is decades long,” not just a month. So, half or more of the lead in our blood represents lead from past exposures just now leaching out of our bones back into our bloodstream, and this “gradual release of lead from the bone serves as a persistent source of toxicity long after cessation of external exposure,” that is, long after leaded gasoline was removed from the pumps for those of us that who were around back before the 1980s.

So, the answer to where the lead comes from is like Pogo’s We’ve met the enemy and he is us or that classic horror movie scene where the call is coming from inside the house.

The amount of lead in our bones can actually be measured, and research shows higher levels are associated with some of our leading causes of death and disability, from tooth decay and miscarriages to cognitive decline and cataracts. “Much of the lead found in adults today was deposited decades ago. Thus, regulations enacted in the 1970s were too late” for many of us, but at least things are going in the right direction now. The “dramatic societal decreases” in blood lead in the United States since the 1970s have been associated with a four- to five-point increase in the average IQs of American adults. Given that, a “particularly provocative question is whether the whole country suffered brain damage prior to the 1980 decreases in blood lead. Was ‘the best generation’ really the brain damaged generation?”

I’m such a sucker for science documentaries, and my favorite episode of Cosmos: A Spacetime Odyssey was The Clean Room, which dealt with this very issue. Trivia: Carl Sagan was my next-door neighbor when I was at Cornell!

If you want to find out How the Leaded Gas Industry Got Away with It, check out that video. How the Lead Paint Industry Got Away with It is similarly scandalous. Lead in Drinking Water offers the modern-day tale of what happened in Flint, Michigan, and “Normal” Blood Lead Levels Can Be Toxic explores the impacts on childhood development.


I close out this extended video series on lead with information on what we can do about it:

Interested in learning more about lead being absorbed and released in our bones, and how calcium supplements may affect that process? See The Rise in Blood Lead Levels at Pregnancy and Menopause and Should Pregnant Women Take Calcium Supplements to Lower Lead Levels?.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

 

Why You Don’t Want “Normal” Blood Lead Levels

“By the 1950s, lead—a dangerous neurotoxin that was once buried deep in the ground, far away from humans—had polluted the entire planet.” We have leaded gasoline to thank for this. It’s hard to imagine “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” and our neighborhoods with it.

“Overall, about 5 million metric tons of lead was deposited in the environment as a result of the combustion of leaded gasoline” by our automobiles before it was regulated. A single busy street could receive more than a metric ton a year, and the lead just built up, decade after decade. Finally, thanks to regulations starting in the 1970s, we stopped spewing so much into the air. As you can see at 0:57 in my video “Normal” Blood Lead Levels Can Be Toxic, as lead use dropped, so did the levels of lead in our blood, resulting in a 98 percent reduction in the percentage of young children with elevated blood lead levels. Of course, the term “elevated” is relative.

“Prior to 1970, lead poisoning was defined by a blood lead concentration of 60 mg/dL or higher” but “since then, the blood lead concentration for defining lead toxicity gradually has been reduced” to 40 mg/dL, then 30 mg/dL, then 25 mg/dL, and then further down to 10mg/dL, as lead levels “previously thought to be safe or inconsequential for children have consistently been shown to be risk factors” for cognitive and behavioral problems.

Currently, an elevated blood lead level is considered to be more than 5 mg/dL. So, under 5 mg/dL, your lead level is considered to be non-elevated or normal. But what does having a “normal” lead level mean?

“Virtually all residents of industrialized countries have bone lead stores that are several orders of magnitude greater than those of our preindustrial ancestors.” If you go to a museum and test the lead levels of ancient skeletons buried a millennium ago, they are a thousand times lower compared to people today, “which indicates the probable existence within most Americans of dysfunctions caused by poisoning from chronic, excessive overexposures to industrial Pb lead.”

You can see a graphical representation of “body burdens of lead” in a preindustrial ancestor, a typical American citizen, and a person with overtly symptomatic lead poisoning, where he might be doubled over in pain, at 2:30 in my video. What the medical and research communities had failed to understand is that they had only concerned themselves with people with actual lead poisoning and those at “typical” lead levels, but “the new value for natural lead levels in [preindustrial] humans shows that typical levels of lead in humans are quite definitely not properly described by the term ‘very low levels’ at all, but instead constitute grossly excessive, 1000-fold over-exposure levels.”

 The bottom line? “No level of lead exposure appears to be ‘safe’ and even the current ‘low’ levels of exposure in children are associated with neurodevelopmental deficits,” including reduced IQ. It could have been a lot worse if we hadn’t started restricting leaded gas. Thanks to falling blood lead levels starting in the 1970s, preschoolers born in the 1990s were two to five IQ points higher than kids like me born before 1976. So, when we see our kids and grandkids being such wizzes at technology that it’s hard to keep up with them, a small part of that may be them not suffering as much lead-induced brain damage as we did. And, what that means for the country is potentially hundreds of billions of dollars of improved productivity because our children are less brain-damaged.

If that seems like a lot for just a few IQ points, as you can see at 4:26 in my video, what you have to realize is that even a small shift in average IQ could result in a 50 percent increase in the number of the “mentally retarded,” millions more in need of special education and services.

So, “removal of lead from gasoline in the United States has been described as one of the great public health achievements of the 20th century, but it almost did not happen.” Indeed, “tremendous pressure by the lead industry itself was brought to bear to quiet, even intimidate, researchers and clinicians who reported on or identified lead as a hazard.” Decent “scientists and health officials faced enormous opposition but never lost sight of the mandate to protect public health.”

Two of the “young, idealistic employees” at the newly formed Environmental Protection Agency, who played key roles in the fight, recount how “naïve [they were] to the ways of Washington”:

“Our youth was also used against us. Our inexperience was cited as a reason for rejecting the lead regulatory proposals….Finally, in retrospect, our youth and inexperience also helped us to succeed in taking on a billion dollar industry. We were too young to know, that regulating lead in gasoline was impossible.”


What about lead exposure after childhood? That’s the topic of my video The Effects of Low-Level Lead Exposure in Adults.

What can we do about lead exposure? See:

If you missed the first three videos in this series, check out:

For the effects of mercury, another heavy metal, see:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

The Flint Lead Crisis May Be the Tip of the Iceberg

Back in the 1960s, a Pulitzer prize-winning scientist described the problem of childhood lead poisoning as “so well defined, so neatly packaged with both causes and cures known, that if we don’t eliminate this social crime, our society deserves all the disasters that have been forecast for it.”

As I discuss in my video Lead in Drinking Water, “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.” Unfortunately, “many policy makers consider the costs of action primarily in economic and financial terms and ignore the costs of inaction on human health and communities’ livelihoods.”

“At this point, most Americans have heard of the avoidable and abject failure of government on the local, state and federal level; environmental authorities; and water company officials”—in fact, failure across the board—“to prevent the mass poisoning of hundreds of children and adults in Flint, Michigan.”

“A government plan to save some money had led public officials to switch the city’s water source from Lake Huron to the Flint River, once the sewer for the auto industry.” Flint citizens “complained that their tap water was foul and discolored. But city, state, and federal officials took no heed.”

Why? Could it have anything to do with the fact that those who complained are “among the poorest in America, mostly African American”?

Officials failed to act for eighteen months, “until a local pediatrician revealed dramatically elevated lead levels in children’s blood.” An investigation didn’t just find fault but highlighted seeming falsification of water-quality results to keep people in the dark.

Though “the specific breed of alleged government corruption” may be unique to Flint, “the end result might not be so rare in the USA—home to an ageing water system.” As the president of the Children’s Health Fund said, “The Pandora’s box is now wide open.” Flint may be only “the tip of an enormous iceberg”—potentially “just one of a great many icebergs.”

“In addition to lead-based paint and residual lead in soil”—found everywhere from leaded gasoline—“a significant source of childhood lead exposure occurs through drinking water as a result of leaching from lead pipes, lead solder, or brass fixtures.” This has been recognized to be a health issue in the United States as early as 1845, a year our flag only had 26 stars. Yet, the use of lead in water pipes and solder was not restricted until the Safe Drinking Water Act Amendment, 141 years later. Was the city you’re living in built before 1986 when the amendment was passed? Today, the “exact number of lead water pipes currently in use is not clear” as about one in three cities surveyed shrugged their shoulders, “not being able to state how much lead piping exists.”

There are anti-corrosion chemicals you can add to tap water to try to keep the lead in the pipes. Flint could have done that, but it could have cost about $100 a day. Today, “the cost of repairing the Flint water system is estimated at $1.5 billion…”

Let me close with a quote from the heroic pediatrician who blew the whistle, Dr. Hanna-Attisha. She was asked, “What advice would you have for other physicians taking on a whistle-blower role?” She replied, “This is our job. This is why we went to medical school—to help people.”

Wasn’t there lead in paint, too, for the longest time? Yes, and that’s the subject of my video How the Lead Paint Industry Got Away with It. And what about leaded gasoline? How many of you remember going to the pumps and seeing the choice between leaded and unleaded? That’s the subject of How the Leaded Gas Industry Got Away with It.


I also get into what the effects are and what we can do about it. Check out:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations: