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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:


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

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

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  1. Where I live,the discussion about bloodlevels of lead due to high concentrations in the soil has started last year.I am wondering if people who live in areas where leadore is natural in the soil and has been mined for centuries have adapted better,with better detoxification meassures than people who lived in areas without naturally occcuring lead and just “now” being,in modern times,being exposed to it.

  2. Actually, I am joking but I was thinking about it yesterday.

    My friends who made money all worked in medical or education or insurance. (Or the entertainment industry)

    Of my closest friends, my highest-paid friend lost her job last year and she was tearing up yesterday because she is struggling financially and she has an aggressive daughter who just bought a half-million-dollar dream house with her husband and because she is aggressive, she ends up in leadership.

    Same with my aggressive sister-in-law and my aggressive step-mother was the same.

    When I looked up the difference that IQ points made, an article said that by age 35, every IQ point increase, on average, earn you $810 more per year.

    And that 3 IQ points were the difference between clerical work and managerial work.

    The thing is I valued EQ more and still do and my sister-in-law was complaining yesterday that unemployment doesn’t pay her exhorbitent salary and that people who make nothing were taking advantage of the $600 per month extra money and I paused and gave my spiel about how half of Americans make under $33,000 per year and a quarter of Americans make under $22,000 per year and 12 million Americans make under $9,000 to live on for a family of 3 and 6 million Americans make zero money at all and are unemployable.

    And I remarked that I smiled a little bit that half of Americans were making more than their take-home pay per week for a few months and she got mad. She has just about zero EQ but she has pretty good IQ and she really is in leadership wherever she goes.

    I walk around trying to figure out how to help the homeless and she focuses on how to have enough money to be a snowbirder with expensive cars and all the right finishes.

    It has been obvious that I probably have low IQ and brain damage in the first place but talking to those 2 yesterday, I wouldn’t have wanted to be what it took to have their economic benefits.

    I would have been giving it to the missionaries.

    1. I’m with you . No idea what my IQ is. I know I’m no wiz by a LONG shot. I earn a decent living. I do like nice stuff, don’t get me wrong but having QUALITY relationships is much more important to me than a huge bank account.

  3. It’s obviously great that we’re getting lead levels down, down, down, but that is definitely not enough for the future of our country. Predictions are that by 2050 HALF of American children will be on the autism scale. So how are we going to turn that one around? Nobody seems to really have a handle on that.

        1. PCB’s are another one.

          Aluminum is linked, though more tentatively

          Air pollution is linked (Dr Greger had that in a video)

          The mother’s diet and things like gestational diabetes are linked.

          I did see the MIT study on RoundUp that Zach Bush talks about but it just seems like it he speaks in all-encompassing ways about things even when the answers are more complicated.

            1. The insufficient pruning of synapses due to elevated mTor is interesting. Perhaps it will turn out that the rise of autism is largely due to the frequent and nearly constant snacking that children never used to do in the past.

              mTor inhibits autophagy in a similar way that insulin inhibits lypolysis. That’s my understanding, anyway.

      1. Blair,

        Correlation is not causation. At best, it’s an invitation to experimentation.

        Or, it’s simply hilarious, a coincidence, as these graphs demonstrate:
        This first one is “US spending on science, space, and technology correlates with Suicides by hanging, strangulation and suffocation.”

        Check it out. There are several examples. Apparently, allegedly, there are 30,000. I wonder if there’s one correlating autism with round-up use?

  4. I was raised in poverty but in rural N.C. but nobody knew. We melted lead from old print type swept out behind the local print shop in tin cans on the kitchen stove. We made toys from it. Some lucky kids had soldier molds. Our house had peeling paint dropping from the ceiling. I became an electrical engineer (MSEE,PE) with more than my share of patents. Everyday I soldered circuits together and seldom washed before lunch. After retiring at 54 I had my physician check blood lead levels. The levels came back as unmeasurable.

    1. Ben, I have a similar story as you. Grew up in poverty in the south after WWII. I remember those lead soldier molds, where molten lead was poured into the top and when it cooled made a very accurate little figure. They were quite popular after the war. I lived in an old wooden house with lead paint. And that was the age of highly leaded gasoline. I worked my way through college and became a successful mathematician, then a systems engineer, and eventually moved to the north. Never became “rich”, but always had enough to buy fruits and vegetables :-)

      Another person who grew up poor and that I really admire is Dr Ben Carson. He, too, grew up in poverty in Detroit which I’m sure had lead paint on the walls as most houses did in those days. And again, plenty of leaded gasoline with the exhaust filling the air before catalytic converters were put on cars. He later became a top surgeon at Johns Hopkins.

      The bottom line is: Maybe all of us in that generation lost a bit of “IQ”, but the human body must have a pretty good way of mitigating the damage. I think I remember a Thomas Edison quote something of the effect: “Success is 90% perseverance and hard work, and 10 % intelligence.”

        1. Hi Deb, No, I haven’t watched the Atomic Cafe, but will check it out.

          I do remember the mercury, though. Some kids would break thermometers to get some to play with. And for a while it was used in light switches because it’s a good conductor of electricity, but I don’t think it’s used for that any longer.

          But mercury is still used in fluorescent bulbs! I remember when the government wanted everyone to switch to CFL’s! I waited until LED’s were perfected and switched to all LEDs because they last much longer, use less electricity, and produce less pollution.

          1. Darwin,

            It was the coolest thing ever to play with. It still brings joy to my heart, even though it probably killed so many brain cells that I don’t know any better than to fondly remember how much fun it was.

            Right up there with the rock tumbler and postcard and stamp and coin collections.

            I highly, highly recommend The Atomic Cafe. Even though it was a few decades ago that I watched it. It is so quirky and funny and just an amazingly jaw-dropping illustration of cultural naiveté and scientific irresponsibility and governmental propaganda in action.

          2. The USA does have a seriously dark history about so many topics but the older generation was able to mess up in ways that there was always a funny story to tell. The Atomic Cafe could have been told in a dark way, but instead, they told it the way it happened.

            My cousin had surgery today and his sister and I laughed for 45 minutes telling old family stories. Those funny stories have served us well our whole lives.

  5. Lead in the environment due to leaded gasoline is just one spectrum of the problem. There are many older homes built before 1978 that are contaminated with lead-based paint. Working for the State Health Department of where I live, I know from experience that most children are exposed to lead from hand to mouth activity. That hand to mouth activity in older homes with deteriorated lead-based paint (lead dust particles) are the cause. Children under the age of 6 are especially at risk because they exhibit more hand to mouth activity than older children and adults, and their brains are still rapidly growing. And if lead-based paint in older homes and environmental lead contamination caused by years of automotive combustion of leaded gasoline is not enough, then we have imported products from countries such as China, India and Mexico that have products that are contaminated with lead. Pb (Lead) is a much more complex topic to point at just one source.

  6. Lead like Mercury, Arsenic and Aluminum have no use in our “complex biologic” systems. We can learn from the elimination of Pb from gasoline and paint. The lesson is that it is best to apply the “precautionary” principle and avoid these substances. It is nice that the gov’t regulations have helped with lead. The government has failed with the others… Al, Ar, Hg,,, along with many other environmental toxins such as persistent organic pollutants like dioxins… all best avoided. It is always nice to put things in context. As my colleague, Dr. Doug Lisle, likes to say… proportion of variance explained. So when making lifestyle changes it is fine if you want to avoid Aluminum to stop using antiperspirants but what about “processed cheese”… see and Arsenic in chicken is another good example… don’t forget to subscribe to and use the extensive video library to check out the science on which to base you and your families journey to improved health and lowered risk of chronic conditions. It would be nice if the health care industry did research about the “upstream” causes of significant conditions which most likely have an environmental basis such as Alzheimer’s and Autism. Be well and bon chance.

    1. Don,

      I came here with such brain problems and have slowly done a long list of things.

      All of it is genuinely so complicated.

      The videos help, but it takes so much time to learn it that it is more doing one thing at a time.

      I got rid of the aluminum antiperspirant and got rashes from the baking soda brands.

      It is like peeling an onion and you don’t even understand what is making you cry.

  7. Dr. Greger, is it safe to consume 1 TBLS of cocoa powder per day? I’ve heard it has lots of antioxidants, but also contains lead and cadmium. Should I be concerned about the heavy metals content? You said people absorb less lead with a meal, and particularly soy, but you said dont put soy in beverages because it blocks the antioxidants. And do all foods with protein block antioxidants or just soy milk?

    1. Mary,

      They say that the amount of cadmium depends on which country it comes from. Latin America = high cadmium. West Africa has lower cadmium.

      Navitas Organics Cacao Powder tested pretty well, so did Pure Natural Miracles Cacao Powder.

      1. There is only one brand that I found listed that was also low in lead but I couldn’t find it on-line.

        The lead is from processing the beans. They said that it was in the shells rather than in the beans themselves but contaminates the beans during the processing.

        I wonder if you could melt Ghiradelli Intense Dark Midnight Reverie (86% Cacao)

        That tested well for both lead and cadmium.

        Or get the low cadmium brands and you might be able to use Modified Citrus Pectin for the lead.

        I have used it as part of my brain healing process.

        I think they got results in 24-hours. Though I sometimes get confused by the wording of studies.

        It was real hospitalized children who had tested high in lead

        If you have kidney problems, maybe be more careful, but they got a 161% decrease of lead in the blood and 132% came out in the urine. The rest might be in the kidneys, but most came out of the body and that sounded good to me.

    2. 1 TBS of cocoa powder is equal to 5 grams which is considered a normal serving Dr. Greger metions using 2 Teaspoons of cocoa powder for the chocolate shake he recommends. As far as lead and cadmium-cocoa does contain these metals so you shouldn’t overdue. Here’s what the The European Food Safety Authority recommends 0.1 ounces (2.5 grams) of high-flavanol cocoa powder or 0.4 ounces (10 grams) of high-flavanol dark chocolate containing at least 200 mg of flavanols per day to achieve heart health benefits (44).Aug 9, 2018 –and without the worry of consuming too much lead or cadmium.

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