The Lead-Crime Hypothesis and a Gripe About Mobile

I’ve generally kept my advocacy for the Lead-Crime Hypothesis off this blog. This is a blog about web-enabled education, after all. But today I can probably get away with it because there’s a web literacy connection. Seriously, I promise.

For those who don’t know the lead-crime hypothesis, it goes like this: the massive crime wave of the late 70s to early 1990s in the U.S. — the crime wave that gave us our politics as we have them now, since it was seen as a failure of liberalism — that crime wave was caused primarily by youth exposure to lead, a result of the most massive public poisoning in the history of the world: the sale and use of leaded gasoline.

In this theory, early lead poisoning, especially in urban areas, affected the mental development of many children, making them more prone to violence and a host of other cognitive and behavioral issues. Roll those behaviors forward 18 years or so, and that early lead exposure becomes a crime wave.

You see why I don’t mention this on the blog much, even though I’ve been annoying friends with it for years. It sounds pretty tin-foil hattish, even though it’s a pretty solid hypothesis.

Anyway, I wanted to make a point about mobile learning, and today I get to do it by talking about lead.

So here’s the thing: I’m reading through an old New Scientist article from 1971 for another purpose (history of computing in education) when I see an article adjacent to the one I’m reading on lead poisoning.

I can’t resist. In it is this paragraph:


From “Is Lead Blowing Our Minds? New Scientist, May 27, 1971.

There’s a whole host of of questions that occur to me reading this. The first question is how that Manchester average child exposure compares to Flint, Michigan. I open a new tab and do a web search for lead blood level in Flint. It turns out that 30 children in Flint had levels above 5 micrograms per deciliter. Twenty-three of them were under six:

Unfortunately there’s a mismatch in unit here, so we’re going to have to covert 5ug/dL to parts per million. So we open another tab and find a converter:


Then we convert. I actually know this conversion, but I like doing it here to make sure I don’t mess it up by a decimal place:


OK, so here’s some context then that should blow your mind. In Flint there were 30 children that tested above the dangerous level of 5 ug/dL. This was the crisis. Yet, according to the New Scientist article, in 1971 the average blood level in children in Manchester UK was six times that, at 31 ug/dL. And unlike in Flint, that wasn’t temporary — that was over their entire childhood.

As usual, when I look at lead stuff, I have to flip back and forth multiple times. The numbers shock me every time. But I think I did this right. (You’re welcome to check me here).

We can have some more fun here. The Flint article says:

Any child who tests 45 micrograms per deciliter or higher must be immediately treated at a poison center, Wells said. No children have tested at that level.

We return to that New Scientist article:

A recent study of Manchester children showed an average of 0.31 ppm, with 17 percent over .50 ppm…

Again, that conversion show 17% of Manchester children had levels over 50 ug/dL. So maybe 20% of the 1971 population of Manchester, if they were alive today, would likely be rushed to a poison center for immediate blood chelation.

So that’s some context.

So now for the hypothesis. The end of that paragraph says that Finland had the highest lead levels in 1971 and Sweden the lowest in a multi-country study. This is a great find because Finland and Sweden should have similar-ish cultures, but different lead exposures. According to the lead hypothesis if we go forward 18 years or so we should find that Finland has a significantly higher crime rate than Sweden.

We make this hypothesis before we go, and decide to look at the murder rate, since it is the most comparable across countries (other violent crimes can vary in definition and record-keeping, but murder is murder).

So we open up my go-to resource for nation data — Nation Master. Unfortunately comparisons for 1989 are not available. But 1995 comparisons are, so we’ll take it:


And what do we find? Score another point for the lead hypothesis: the rate of murder in Finland, the high-lead country, is three times of that in Sweden, the low-lead country.

The whole process takes about ten minutes, maybe a bit less. But at the end of it, my tabs look like this:


With about a third of those tabs opened up in the course of looking at this.

I’m not saying that I proved anything here. I could still be a nut about this leaded gasoline and crime hypothesis.

But I am saying that this is what literate web reading looks like. You read things, and slide smoothly into multi-tab investigations of issues, pulling in statistical databases, unit converters, old and new magazine articles, published research.

Now here’s my question — if I read this on my phone, how much of this could I have done? My experience tells me almost none of it. On a laptop we built all this context, developed an informal hypothesis and tested against a database. On a phone, I doubt we could have even made it through the first Flint search without wanting to throw our phone across the room.

We know that this sort of multi-tabbed environment is productive — it was, of course, one of the major breakthroughs of Xerox PARC — multiple windows between which you could copy and paste text. If you want your computer to be more than a consumption tool you need that sort of functionality.

The mobile web takes that all away, makes us dumber and less investigative. Yet year after year we hear people talking about the promise of mobile learning.

It’s not only wrong — it’s harmful.

As educators, I’m going to propose a different question. Not “How do we promote mobile learning?” but instead, how do we stop it?

How do we get kids to work on laptops, and stop reading on phones? How do we get them to learn the techniques of multi-tab investigations? Because this world where we’ve started reading everything on single-tabbed phone browsers, without workable copy and paste, without context menus, without keyboards? It’s going to make us very dumb compared to the people that came before us. And I think we need all the intelligence we can use right now.

5 thoughts on “The Lead-Crime Hypothesis and a Gripe About Mobile

  1. It’s more than that – most schools 1-1 programs use iPads which have all sorts of limitations, including inability to use add blockers, or simplify articles to block out all the clutter since can’t cope with chrome extensions all us desktop users rely on. So we can’t train kids from elementary. And it seems that digital habits are formed before the age of 12… (heard that at a librarian workshop – need to fact check it!)

  2. I’m a little bothered by the conversion of µg/dL to ppm. Parts per million is count/count; µg/dL is weight/volume.

    ‘ppm’ is a “troublesome” unit, in that it really could mean many things. It could be number of molecules of the contaminant per molecules of the substance, or mass of contaminant per mass of substance, or volume of contaminant per volume substance. The first and last are equivalent(ish) for gases due to Avogadro’s Law, which makes ppm tend to make sense in that setting. However, for liquids it is not so easy.

    Looking up lead testing procedures, I see the use of an ICP-AES mass spectrometer to perform the analysis in soils, which is measuring dissolved samples. The results are in “ppm” which is roughly equal to µg/mL assuming a well-dissolved aqueous solution.

    All of which makes me wonder how the sampling process reported in the New Scientist (parts per million) actually relates to the new µg/dL SI-based standards. I could imagine if the blood samples were fed directly to the ICP-AES machine then so long as blood’s density is roughly equivalent to water (which it appears to be, about 1.06x the density of water, which is close enough for our purposes) then ‘ppm’ there is roughly equivalent to µg/mL, and your calculations stand (off by about 6%, but that’s not enough to change the analysis).

    Also, separately, I saw reports of ~50-80 µg/dL lead content in certain industry workers, so the highly-elevated toxic levels of lead are certainly not unheard of.

    The point is, relying on unit conversions on the web is great when the units are like-to-like (mass/volume to mass/volume), but not when they are not. I think your conclusion is accurate, but it would be more convincing if we had a better conversion between those units specific to the measurement the New Scientist article was quoting.

    • Agreed. I’ve been enjoying your series on fact checking, so I guess it’s appropriate to make this comment — the unit conversion set off instant alarm bells and would be the first thing I would fact-check. It’s unfortunately extra obscure, because without looking up the densities I can’t even estimate whether the unit conversion is wildly off or just slightly off as the above commenter seems to have found.

      Keep up the good work, I really enjoy reading your writing.

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