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:

How the Lead Paint and Gas Industries Got Away with It

We have known for thousands of years that lead can be toxic and for more than a century that children could be poisoned by lead paint. Since those first cases, the “lead industry has mobilized against the advances of science,” as I discuss in my video How the Lead Paint Industry Got Away with It.

By 1926, lead poisoning was already “of relatively frequent occurrence in children,” yet “the United States continued to allow the use of lead-based paint until 1978.” In contrast, in Europe, many countries said, Hmm, poisoning children? No, thanks. and “banned the use of lead-based paint as early as 1909.” 

“The delay in banning lead-based paint in the United States was due largely to the marketing and lobbying efforts of the lead industry,” profiting from the poison. It knew it couldn’t hold off forever, but the industry boasted that its “victories have been in the deferral of implementation of…regulations.”

And now, “peeling paint turns into poisonous dust,” and guess where it ends up? As a Mount Sinai dean and a Harvard neurology professor put it: “Lead is a devastating poison. It damages children’s brains, erodes intelligence, diminishes creativity…” and judgment and language. Yet, despite the accumulating evidence, the lead industry didn’t just fail to warn people—“it engaged in an energetic promotion of lead paint.” After all, a can of pure white lead paint had huge amounts of lead, which meant huge profits for the industry.

But, as you can see in an old advertisement featured at 1:55 in my video, “[t]here is no cause for worry” if your toddler rubs up against lead paint, because those “fingerprint smudges or dirt spots” can be removed “easily without harming the paint.” Wouldn’t want to harm the paint. After all, “painted walls are sanitary…”

The director of the Lead Industry Association blamed the victims: “Childhood lead poisoning is essentially a problem of slum dwellings and relatively ignorant parents.”

“It seems that no amount of evidence, no health statistics, no public outrage could get industry to care that their lead paint was killing and poisoning children,” but how much public outrage was there really?

“It goes without saying that lead is a devastating, debilitating poison” and that “literally millions of children have been diagnosed with varying degrees of elevated blood lead levels…” Compare that to polio, for example. “In the 1950s, for example, fewer than sixty thousand new cases of polio per year created a near-panic among American parents and a national mobilization that led to vaccination campaigns that virtually wiped out the disease within a decade.” In contrast, despite “many millions of children [who have] had their lives altered for the worse by exposure to lead…[a]t no point in the past hundred years has there been a similar national mobilization over lead.” Today, after literally a century, the Centers for Disease Control and Prevention estimates over five hundred thousand children still suffer from “elevated blood-lead levels.”

The good news is that blood lead levels are in decline, which is celebrated as one of our great public health achievements. But, given what we knew, and for how long we knew, “it is presumptuous to declare the decline in childhood lead poisoning a public health victory.” Indeed, “even if we were victorious…it would be a victory diminished by our failure to learn from the epidemic and take steps to dramatically reduce exposures to other confirmed and suspected environmental toxicants as well as chemicals of uncertain toxicity.”

That’s one of the reasons I wanted to do this series on lead. We need to learn from our history so the next time some industry wants to sell something to our kids, we’ll stick to the science. And, of course, lead levels aren’t declining for everyone.

As the whistle-blowing pediatrician who helped expose the Flint drinking water crisis explained, “The people in Flint have a 20-year lower life expectancy than people in a neighboring suburb. We were already struggling with every barrier to our children’s success. Then we gave them lead.”

Her research showed that the switch in water supplies from the Great Lakes to the polluted Flint River “created a perfect storm” for lead contamination, doubling the percentage of kids with elevated lead levels in their blood, as you can see at 0:42 in my video How the Leaded Gas Industry Got Away with It, whereas out in the suburbs, where the water supply remained unchanged, children’s lead levels stayed about the same. That’s how she knew it was the switch in water supplies. That’s what broke the story of the Flint crisis: a doubling of elevated lead levels.

But wait a moment: Even before the switch from Lake Huron to the polluted Flint River, when everyone was getting the same water, lead levels in children in Flint were twice that of the suburbs. There was already a doubling in elevated lead levels in Flint and other poor communities around the country, but where have all the crisis headlines been? Indeed, even with all the bottled water in the world, the children in Flint will continue to live in a lead-polluted environment.

Many have pointed out the irony that the new water from the Flint River was “so corrosive” that the nearby General Motors plant switched back to a clean water source when it started noticing rust spots on its new parts, all while water quality complaints from Flint residents were being ignored. But, there is an additional irony: General Motors is a major reason why the world is so contaminated with lead in the first place, as GM invented leaded gasoline. “Shortly after manufacture began, workers…began to become floridly psychotic and die.”

“In the wake of blaring headlines” about the lead-poisoned workers, public health leaders “warned of the potential for damage to broad swaths of the population” posed by putting this “well established toxin” into gasoline, “into the daily lives of millions of people. Yet, despite these warnings, millions…were harmed…and this entirely preventable poisoning still occurs today.”

“Virtually all the lead in the environment is there as a result of human activity.” Because we put it there. It used to be locked away, deep underground or under the ocean, but that was before we drove it around the Earth. “In the early 1970s, 200,000 tons of lead was emitted from automobiles in the United States each year, mostly in urban areas.” Had lead not been added to gasoline, the industry would have had to use higher-octane gas, which is less profitable. So, the “oil and lead industries…successfully thwarted government efforts to limit lead in gasoline for 50 years.” But, how were they able to do that? “Early public health warnings were not heeded because the industry assured the scientific community and the public that there was no danger.” I could see how a gullible public might be swayed by slick PR, but how do you manipulate the scientific community? By manipulating the science.

“The lead industry was able to achieve its influence in large part by being the primary supporter of research on health effects of lead,” and it got the best science money could buy. “Long before Big Tobacco, the lead industry understood the inestimable value of purchasing ‘good science.’”

“Consequently, the vast majority of relevant studies of lead in gasoline published [for decades]…were favorable to the lead industries.” What’s more, they “even sent a delegation to try to convince the U.S. EPA administrator that the lead regulation was not necessary because they alleged lead was an essential mineral required for optimum growth and development.”

Of course, the exact opposite is true. Lead is toxic to development. There are, however, nutritional interventions that can help alleviate lead toxicity. For example, there are food components that can help decrease the absorption of lead and help flush it out of your body. I’ve produced a series of three videos on specific dietary interventions, such as particular foods to eat, but—spoiler alert—in general, “food patterns that reduce susceptibility to lead toxicity are consistent with the recommendations for a healthy diet.”

As soon as I learned about the unfolding crisis in Flint, Michigan, I knew I had to take a deep dive into the medical literature to see if there is anything these kids might be able to do diet-wise to reduce their body burden.

Most of the time when I cover a subject on NutritionFacts.org, I’ve addressed it previously, so I just have to research the new studies published in the interim. But I had never really looked deeply into lead poisoning before, so I was faced with more than a century of science to dig through. Yes, I did discover there were foods that could help, but I also learned about cautionary tales like this one about our shameful history with leaded paint. By learning this lesson, hopefully, we can put more critical thought into preventing future disasters that can arise when our society allows profits to be placed over people.


This is part of a series on lead. You can view the rest of the series here:

 You may also be interested in How to Lower Heavy Metal Levels with Diet.

If you enjoyed this article, you may also like:

What relevance does this have for us today? See, for example, my video How Smoking in 1959 Is Like Eating in 2019.

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:

Vegans Should Consider Taking DHA Supplements

We are all fatheads.

Indeed, about half the dry weight of our brain is fat. Lower levels of the long-chain omega-3 fat DHA in some areas of Alzheimer’s brains got people thinking that perhaps DHA is protective. Since the level of DHA in the brain tends to correlate with the level of DHA in the blood, cross-sectional studies of dementia and pre-dementia patients have been done. The result? The dementia and pre-dementia subjects do tend to have lower levels of both long-chain omega-3s, EPA and DHA, circulating in their bloodstream. This doesn’t necessarily mean that lower omega-3 levels cause cognitive impairment, however. It was just a snapshot in time, so we don’t know which came first. As I discuss in my video Should Vegans Take DHA to Preserve Brain Function?, maybe the dementia led to a dietary deficiency, rather than a dietary deficiency leading to dementia.

What we need is to measure long-chain omega-3 levels at the beginning and then follow people over time, and, indeed, there may be a slower rate of cognitive decline in those who start out with higher levels. We can actually see the difference on MRI. Thousands of older men and women had their levels checked and were scanned and then re-scanned. The brains of those with higher levels looked noticeably healthier five years later.

The size of our brain actually shrinks as we get older, starting around age 20. Between ages 16 and 80, our brain loses about 1 percent of its volume every two to three years, such that by the time we’re in our 70s, our brain has lost 26 percent of its size and ends up smaller than that of 2- to 3-year-old children.

As we age, our ability to make long-chain omega-3s like DHA from short-chain omega-3s in plant foods, such as flaxseeds, chia seeds, walnuts, and greens, may decline. Researchers compared DHA levels to brain volumes in the famed Framingham Study and found that lower DHA levels were associated with smaller brain volumes, but this was just from a snapshot in time, so more information was needed. A subsequent study was published that found that higher EPA and DHA levels correlated with larger brain volume eight years later. While normal aging results in overall brain shrinkage, having lower levels of long-chain omega-3s may signal increased risk. The only thing we’d now need to prove cause and effect is a randomized controlled trial showing we can actually slow brain loss by giving people extra long-chain omega-3s, but the trials to date showed no cognitive benefits from supplementation…until now.

A “double-blind randomized interventional study provide[d] first-time evidence that [extra long-chain omega-3s] exert positive effects on brain functions in healthy older adults,” a significant improvement in executive function after six and a half months of supplementation, and significantly less brain shrinkage compared to placebo. This kind of gray matter shrinkage in the placebo might be considered just normal brain aging, but it was significantly slowed in the supplementation group. The researchers also described changes in the white matter of the brain, increased fractional anisotropy, and decreases in mean and radial diffusivity—terms I’ve never heard before but evidently imply greater structural integrity.

So, we know that having sufficient long-chain omega-3s EPA and DHA may be important for preserving brain function and structure, but what’s “sufficient” and how do we get there? The Framingham Study found what appears to be a threshold value around an omega-3 index of 4.4, which is a measure of our EPA and DHA levels. Having more or much more than 4.4 didn’t seem to matter, but having less was associated with accelerated brain loss equivalent to about an extra two years of brain aging, which comes out to about a teaspoon less of brain matter, so it’s probably good to have an omega-3 index over 4.4.

The problem is that people who don’t eat fish may be under 4.4. Nearly two-thirds of vegans may fall below 4.0, suggesting a substantial number of vegans have an omega-3 status associated with accelerated brain aging. The average American just exceeds the threshold at about 4.5, though if we age- and gender-match with the vegans, ironically, the omnivores do just as bad. There aren’t a lot of long-chain omega-3s in Big Macs either, but having a nutrient status no worse than those eating the Standard American Diet is not saying much.

What we need is a study that gives those with such low levels some pollutant-free EPA and DHA, and then sees how much it takes to push people past the threshold…and here we go: Phase 2 of the study gave algae-derived EPA and DHA to those eating vegan diets with levels under 4.0. About 250mg a day took them from an average of 3.1 over the threshold to 4.8 within four months. This is why I recommend everyone consider eating a plant-based diet along with contaminant-free EPA and DHA to get the best of both worlds—omega-3 levels associated with brain preservation while minimizing exposure to toxic pollutants.


A list of my recommendations can be found here: Optimum Nutrition Recommendations.

Why not just eat fish or take fish oil? I explain why in these videos:

How else can we protect our brains? See, for example:

In health,
Michael Greger, M.D.

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