david lewis: Almost all adults in the US had more lead in their blood when they were kids than the worst hit children in Flint

When Dr. Hanna-Attisha, the pediatrician who proved to Michigan authorities that Flint’s water supply was a problem, thought about how to present her research at a press conference, she wanted people to realize that the authorities were poisoning kids. She didn’t want to use a real case of a kid who tested high for privacy reasons, so she made up a “hypothetical” kid named Makayla for people to think about. Here’s part of a slide from that presentation:

Keep that 6 µg/dL figure in mind.

I wondered at all the talk emanating from Flint, about permanent brain damage, these kids need to be monitored for the rest of their lives, this is a public health emergency, etc.

As I researched, I realized it’s all true. I would use different words to describe the situation, but there is no doubt that hypothetical Makayla would be far better off if she hadn’t been poisoned by the Flint City water manager backed up by state and even some federal employees, to the degree that her blood lead level got as high as 6 µg/dL.

But something else dawned.

This whole thing is about levels of lead 1/3 as high as just about everyone born in the US lived with in 1980.

In those ancient days 35 or more years ago, when a lot of the Flint parents were kids themselves, there was lead spewing out of the tailpipe of every car that drove by. Everyone breathed it in. White paint used inside of homes in the 1950s was 50% lead compounds. Kids crawling on floors would pick up dust and chips and put it in their mouths.

Plumbers used lead solder on copper pipes and thought nothing of it. Older homes had lead pipes. No one worried about lead in water.

Check this chart out. It shows the blood lead levels of US kids in 1980:

From: Blood Lead Levels for Persons 6 months – 74 years of age United States 1976 – 80

Notice that numbers as low as Makayla's 6 ug/dL were cut out of the left vertical scale. Although kids testing that high today are cause for alarm, in 1980 it was unusual to find a kid with a level that low. That chart shows median values. In 1980, 18% of US black kids were testing at 30 ug/dL, five times higher than the tests everyone finds so alarming in Flint.

Consider people like me. I was born in 1950. If it’s a public health emergency when 10% of the kids in parts of a city like Flint test higher than 5 µg/dL for lead in their blood, people born in 1950 like me might as well sign up to be boat anchors. We were exposed to so much lead we must be made of lead. We all would have had blood lead levels higher than 25 µg/dL as kids.

“Until the early 1970s in the U.S. the acceptable concentration of lead in blood was 60 µg/dL in children and 80 µg/dL in adults”. -from Measuring Lead Exposure in Infants, Children, and other Sensitive Populations (1993)

People haven’t realized that lead contamination of human beings was a product of industrialization, that even today’s typically “low” levels of lead in blood, when compared to preindustrial humans, are incredibly high.

The National Academies assessed the situation in 1991, citing studies such as this, and confirmed that the blood lead level of the average person in the US in 1991 was 300 – 500 times higher than what natives experienced in preindustrial times.

The guy on the right in the figure above is so full of lead he’s flirting with death. The guy on the left is a North American native just prior to when Columbus “discovered” his continent. He’s got almost no lead.

The guy in the middle is me. Or you.

The point is that blood lead levels formerly and even now considered “normal” are much closer to fatal amounts than the levels present in human blood for almost all of the time humans have been on Earth.

“Science and society have been remarkably slow to recognize and respond to the full range of harm associated with lead exposure, but that is changing.” Measuring Lead Exposure in Infants, Children, and other Sensitive Populations (1993)

Although the issue of whether to add lead to gasoline was debated as early and as high up as when the US Surgeon General convened a meeting of scientists and industry to hash out the issue in 1925, industry got its way when they proclaimed leaded gas was “essential to our civilization”. It took until the 1970s before people realized that due to the fact the entire population was being poisoned, the car companies would have to make cars that could run without lead. They did.

Look at how the average US blood lead level plummeted when regulations were imposed on gasoline and paint:

Chart from "Childhood lead poisoning: the torturous path from science to policy".

As blood lead levels were reduced, researchers had access to kids with lower blood lead levels to study. By 2006 there were “some results even suggesting that the decline in children's IQ scores per unit increase in blood lead level is greater in the range of 0–10 μg/dl than it is above 10 μg/dL” from "Childhood lead poisoning: the torturous path from science to policy".

This was a controversial finding in 2006. The CDC’s posted level of concern was still 10 µg/dL then. It isn’t now.

The bad news kept coming in:

Graphic taken from: Canadian Environmental Health Atlas: Lead Health Concerns

In 2012, the CDC started saying it believes there is no safe blood lead level for children.
“The most sensitive populations are infants, children, and pregnant women; “ From “Blood Lead”. EPA Report on the Environment

“Children, infants, and fetuses are more vulnerable to the effects of lead because the blood-brain barrier is not fully developed in them. Thus, a smaller amount of lead will have a greater effect on children than on adults. In addition, lead absorption can be up to five times greater in children compared to adults” From “Blood Lead”

A kid can drink a glass of water containing lead and absorb 50% of it. An adult might only retain 10% of what’s in that glass. And once the lead is in the kid’s body, it gets to the kid’s brain through the not fully developed blood brain barrier. The body removes lead from blood and stores it in bone, but in kids it also comes back out of bone readily compared to adults.

There are some, like the Michigan state nurse who told a worried mother from Flint: “Its just a few I.Q. points… its not the end of the world”, who don’t get it. Here’s a chart that shows what happens if you lower I.Q. by 5 points over an entire population:

In this affected population of 160 million, you lose 3.6 million of the “gifted” at the top end, and you gain 3.4 million “mentally retarded” at the low end. Everyone is impaired compared to what they could have been.

As it dawns on more of us that we’ve all been damaged by civilization’s careless use of lead and we seek to do something about it, we should try to keep things in perspective. I’m imagining how the Flint kids feel when they hear of outraged adults, maybe even their own parents, yelling at authorities that their kids are permanently damaged and they are angry that there’s nothing anyone can do about that.

I’m thinking its pretty certain those parents had higher levels of lead in their blood when they were children. The kids need some assurance that we’re working on a big problem and that they, damaged as they are, are actually better off even now than how it was for most adults they know. I think they might feel better knowing this. They aren't doomed.

What is the CDC supposed to do if there isn’t a known safe way to get lead out of the population once its in, when its down to where it is today, i.e. on average below 5 µg/dL and they want the level to approach zero? Their approach is to establish a declining “reference” blood lead level which is now 5 µg/dL.

They calculate what this reference level is by estimating how contaminated the most contaminated 2.5% of the population of US kids is. That’s 600,000 kids, give or take. The CDC has already estimated how contaminated they are. They would test "elevated" for blood lead, just as Dr. Hanna-Attisha’s hypothetical Makayla did.

So that’s 600,000 US kids, plus the kids in Flint, that are testing higher today than the 5 µg/dL CDC reference level.

Its a much bigger problem than Flint. The “emergency” in Flint is that due to blundering authorities leaded water has been presented as drinkable. Now that everyone knows not to drink Flint water the fact that hundreds or thousands of Michigan kids would test higher than 5 µg/dL is just a part of the national problem of how to slowly get the lead out of our blood.

Its not reasonable to single out Flint kids and tell them they have permanent brain damage compared to just about everyone else in the country. Almost all US children, including the children in Flint who have tested high for blood lead, have lower amounts of lead in their blood than their parents and far lower amounts than their grandparents did when they were children. Progress has been achieved. But because all US children and adults have permanent brain damage and many other problems due to lead, some worse than others, the CDC wants more progress to be achieved.

The CDC blood lead reference level, which is designed to ratchet downward every four years, is published as a way to get authorities to take action to keep lead from getting into children, and to keep getting authorities to act to keep lead from getting into children, until average blood lead levels are far lower than what up until recently were thought to be the low values of today.

The CDC expects average blood lead levels in US kids will continue to decline. They will do an estimate every four years of what the most contaminated 2.5% of children would test at, and declare that to be the new, lower reference level. When authorities start to see kids testing above the reference level, whatever it by then is, they will be told that more lead is getting into their kids than the other 97.5% of US kids, and this realization is supposed to get them to do something about it. As the lead level in US kids continues to decline, the reference level will decline, authorities will take more action in places where kids test high, and as time goes by everyone will be better off.

There will always be 2.5% of kids in the US (today that's about 600,000), who will test higher than the CDC reference level. It’s the definition.

Is it becoming a bit clearer that some might need a bit more perspective when they talk about what happened to the kids in Flint?

The Mad Hatter was Mad because he had absorbed mercury. It’s a heavy metal, like lead, with similar effects.

A few random thoughts:

Why is there an allowable level of lead in water?

EPA has set drinking water standards with two levels of protection.
“The maximum contaminant level goal (MCLG) is zero. This is the levels determined to be safe by toxicological and biomedical considerations, independent of feasibility.
EPA's final rule establishes an action level is set at 15 µg/L” from Lead Toxicity What Are the U.S. Standards for Lead Levels?

(They aren’t saying its “safe”. Because infants absorb so much of the lead in the liquid they drink some say that even with water at 10 µg/L the infant will quickly test higher than the CDC reference level for lead.)

If my water has high lead levels, is it safe to take a bath or shower?

Yes. Bathing and showering should be safe for you and your children, even if the water contains lead over EPA’s action level. Human skin does not absorb lead in water. From CDC, Sources of Lead, “Water”

You're saying the CDC estimates that 2.5% of all US children will test as having blood lead levels as high as the kids who tested high in Flint. What about actual test results?

I found this chart on the CDC website "Number of Children Tested and Confirmed BLL's ≥10 µg/dL by State, Year, and BLL Group, Children < 72 Months Old" which contains raw data of blood lead level testing in the US for the years 1997 to 2014.

The far right column of the chart contains data on the number of US children, by state and year, who tested above 5 ug/dL for blood lead. The bottom of that column shows the 2014 US total, i.e. 105,966. The bottom of the third column from the left shows the number of US children tested in 2014, i.e. 2,496,140.

That's 4.25% of all US children tested in 2014 were above the CDC reference level, just as the kids testing high in Flint are. The CDC would still stick by their estimate of 2.5% because testing for blood lead tends to be concentrated in population groups suspected of having higher lead levels.

The CDC bases its estimate on the best dataset on blood lead in children in the US that exists, i.e. the NHANES dataset. The CDC defines its reference number as the 97.5 percentile value in the NHANES dataset.