
New Zealand Study Provides More Support for Lead-Crime Hypothesis - curtis
http://www.motherjones.com/kevin-drum/2017/12/new-zealand-study-provides-more-support-for-lead-crime-hypothesis/
======
haberman
The title draws the opposite conclusion of the paper itself
([https://jamanetwork.com/journals/jamapediatrics/fullarticle/...](https://jamanetwork.com/journals/jamapediatrics/fullarticle/2666777)):

> Conclusions and Relevance: This study overcomes past limitations of studies
> of BLL and crime by studying the association in a place and time where the
> correlation was not confounded by childhood socioeconomic status. Findings
> failed to support a dose-response association between BLL and consequential
> criminal offending.

The author of this Mother Jones article, a long-time supporter of the
hypothesis, re-analyzed the raw data himself and concluded that (surprise) the
paper reinforces his pre-existing beliefs.

I really desperately want to read scientific information about the world that
I can trust isn't being filtered through the biases and passions of humans. I
want to be able to trust that people are following the data to wherever it may
lead. In our hyper-partisan world, that seems harder and harder to come by.

~~~
gumby
> I really desperately want to read scientific information about the world
> that I can trust isn't being filtered through the biases and passions of
> humans. I want to be able to trust that people are following the data to
> wherever it may lead.

Good luck. That’s inherently impossible (and there’s good science on the
subject).

However your core point is correct: the article is an absurd misrepresentation
of the study. I agree with you that we need more attention to squashing
_concious_ bias.

------
truantbuick
A few things that raised my brow:

1\. The press release for the study and this article have completely opposite
conclusions. At least the author is relatively upfront about this, but he
characterizes it as if the press release is just a cautious, sciencey take on
the results. By the way, it's not just the press release, but the
abstract/paper has pretty unambiguous language saying findings "failed" to
support such hypotheses.

2\. There's a Mother Jones chart that uses data from the study, but it's
cherry picked. They take a few cohorts, ignore the (very valid) adjustment the
study authors made, and the chart itself is IMO misleading because when you
scan it, you're likely to mush up the highs and lows of each cohort to make it
look more linear than it is.

3\. Looking this guy up, he's clearly an advocate around the lead crime
hypothesis, so it should be understood this guy has an angle.

So, yeah, this headline sucks.

~~~
veridies
Responding to your 1: “failed to support” doesn’t mean that they found
evidence that contradicted the lead crime hypothesis. The data they found is
entirely consistent with the lead crime hypothesis; it’s just that it’s within
the realm of possiblity (5%ish chance) that this data would emerge even if the
lead crime hypothesis were false. So they’re “failing” to support the lead
hypothesis when they’re exercising that scientific caution which encourages
false negatives instead of false positives; that doesn’t mean we ought to do
the same.

~~~
dmix
At most you could say it doesnt _disprove_ his lead/crime hyptothesis but
looking at the data and charts he cherry picked (yes I read both closely) it
only very weakly coorelates to his worldview. He even opens the article saying
the lead levels were drasrically lower then continues to pretend that it was
comparable data to the previous US geographic set.

If the author was a good scientist he'd conclude more studies from a broader
population need to be done.

But ultimately just because he acknowledged bias doesnt mean he effectively
accounted for it in his analysis. There's a good reason the authors of the
study took the position they did.

------
Taniwha
Some background (I live in Dunedin the city that this study is based) - this
particular study is part of a much larger multi-disciplinary study where every
child born in one year has been followed throughout their life - they are 45
years in at this point - it's one of the very few such comprehensive studies
worldwide

So you're seeing one profile of lead exposure (the one experienced by people
born 72-73) over their lifetimes - NZ removed lead from petrol later than the
US did, however Dunedin is a relatively small city (~120k people) without
giant freeways/etc so lead levels are likely lower than those in some places
in the US

Here's the study's home page
[https://dunedinstudy.otago.ac.nz/](https://dunedinstudy.otago.ac.nz/)

~~~
dmix
Both the lead levels and population size were far smaller than the original
study. But regardless they failed to find a solid correlation between the two.

It's disapppointing the author presents his own reinterpretation with such
certainty given that context but I really dont expect much from a publication
like MotherJones who are known for their shameless polarized position taking
and bias friendly reporting.

Even viewed in isolation this author was entirely unconvicing in that regard.

------
mr_toad
With only 533 test subjects (most of whom are not criminals), divided into
even smaller groups by levels of lead exposure, it’s not surprising that the
evidence is unclear.

I’d like to know more about why the males had higher lead levels than females.

------
bckygldstn
I think this article is an incorrect interpretation of the research, which
doesn't support the author's three conclusions:

> 1\. Using the unadjusted figures...

The adjustment is to correct for sex. This is explained in the original paper
and supported by their data: The males in the study had higher lead levels as
children and males in general are more likely to commit crime, this alone
causes a correlation between lead and crime.

Correcting for sex is not "unusual": it's done in 99% of research on human
subjects.

> 2\. Using the adjusted figures, there’s a clear association of lead levels
> with later criminal convictions, and the association is effectively
> statistically significant

The authors perform comparisons of blood level with 5 different crime
statistics and only 1 is statistically significant. These comparisons must be
considered together: What causal effect between lead and non-violent crime
would not also apply to violent crime, crime as a whole, first-time offences,
or repeat offences?

Relevant xkcd: [https://xkcd.com/882/](https://xkcd.com/882/)

> 3\. Using the adjusted figures, there’s a clear association of lead levels
> with self-reported offenses, but the statistical significance is poor.

The author bases this conclusion from their chart of self-reports vs lead at
different ages, which does not (as they claim) use the sex-adjusted figures.
The statistical significance is indeed poor for the adjusted values, they got
that right.

~~~
Semiapies
Drum is irrationally invested in the lead-crime hypothesis. There's a strain
of white, technocratic US liberal with a creepy investment in the idea that
programs like urban renewal (bulldoze minority neighborhoods and stuff the
residents in miserable housing projects) didn't fail, but _were failed_ by
those minorites. Back in the day, they were the ones who would mutter about
generic differences in intelligence and _The Bell Curve_ not getting a fair
hearing when they thought the audience was sympathetic.

~~~
neaden
This is in no way a fair reading of Drum on the lead stuff. His basic point is
that the rise and fall off crime is due in large part to lead so you should
ignore politicians who try to claim credit for it with their policing programs
and that we should scale back programs that were initiated during the 80s come
wave. He does not support things like The Bell Curve at all.

~~~
veridies
It’s worth noting Drum’s actual position on The Bell Curve:
[http://www.motherjones.com/kevin-drum/2017/05/charles-
murray...](http://www.motherjones.com/kevin-drum/2017/05/charles-murray-still-
convinced-whites-are-smarter-blacks/)

TLDR: he thinks that there _could_ be an genetic difference in racial IQ
levels, but that the evidence is against it and it makes far less sense than
the environmental explanation.

------
LouisSayers
This looks like someone's picked out a variable and missed the bigger picture.

If people from Dunedin do have a positive correlation between lead in their
blood and criminal convictions, then I'd be asking why the convicts have more
lead in their system in the first place.

From a quick google it looks like lead paint can cause higher blood lead
levels. Perhaps the use of something like lead paint could be highly
correlated to poverty. I know my gran has wallpaper on her walls instead of
using paint - perhaps people in order to save money on their properties used
lead paint instead of wallpaper. Perhaps state houses have more lead in them
than richer family houses.

The point is without knowing much about this area, and from a quick scan of
this article, it seems that they're trying to find evidence to support their
current position of thinking around lead poisoning and crime.

I don't know if what I've mentioned above around housing is accurate at all,
but it's a quick thought off the top of my head to demonstrate a potential for
missing the forest for the trees, or an attempt to find 'evidence' for your
preconceptions.

~~~
xxgreg
Agreed.

If crime is correlated with child poverty, and cheap rentals are old houses
which haven't been renovated in a long time, and tend to have more lead paint.
Then on average criminals will have higher blood lead levels. This doesn't
provide any evidence that lead had any causal affect in crime.

------
leroy_masochist
Could the fact that males have higher blood lead levels be due to the fact
that men work in construction (i.e., taking apart old structures that have
been painted with lead-based paint) at a higher rate than women?

~~~
underwater
They seem to be using the levels at age 11 as a baseline.

------
mjirv
The article implies men tended to have higher lead levels than women
(otherwise, adjusting for sex wouldn't have done anything).

Does anyone know why this would be the case?

------
maxxxxx
I think the way we are handling pollution of all kinds will be seen as totally
nuts by people in the future. We are performing large scale experiments on our
population and even if there is strong indication of toxicity we do nothing as
long as it makes money for someone.

~~~
averagewall
Huh? We stopped using lead in petrol about 40 years ago. You do have to make a
tradeoff between keeping the economy going and unknown risks. We continued to
use concrete despite early fears about the danger of cement dust. We still use
social media despite fears about psychological problems. We still drive cars
despite the high danger of death. Nothing's perfectly safe. We even still have
babies knowing that all of them will die, and worse males will probably die
sooner than females. Abort male foetuses for their own safety? You have to
draw a line somewhere.

~~~
maxxxxx
Lead cleanup for example is way underfunded. If we put the same effort into
that as we do after each terrorist attack there would be no lead paint houses
left in the country and no lead pipes. Car pollution rules would be much
stricter. Stay in an area with no cars for a few weeks and come back to a city
and you suddenly notice how incredibly suffocating car exhaust gas is.

------
smitherfield
I'll echo bckygldstn's criticisms[1] and add a few of my own.

The "lead-crime hypothesis" is a very obvious example of correlation not
implying causation.

For example, rock music causes crime. Rock music grew in popularity in the
late 50's and early 60's, peaked between the late 60's and early 90's, and
declined thereafter. Just like crime! In fact, the harder they rocked the
worse the crime rate got. I guess Tipper Gore was right all along. Rock music
causes crime.

Margarine causes crime. Johnny Carson causes crime. The Boston Celtics cause
crime. The Japanese economy, big hair, VHF television, polyester, yearly
Oldsmobile sales: all cause crime.

During the period leaded gasoline was sold, Canada allowed 0.77 grams of lead
per liter of gasoline, nearly three times the US limit of 0.29 g/l.[2] Yet the
crime rate in Canada was (and continues to be) far lower than in the US.[3]

In Mexico, leaded gas remained commonplace much later than it did in the US,
and yet crime fell dramatically during the period leaded gas was sold, and
_increased_ dramatically after it stopped being sold.[4]

One thing we could look at is people who had the highest lead exposure. Lead
miners, paint factory workers, house painters, fuel refinery workers, gas
station attendants, auto mechanics, etc. I would confidently bet the farm
that, adjusting for sex and income, there was no statistically-significant
correlation between these professions and crime.

Aviation gasoline, as used in small propeller planes, still contains lead. We
could also look at present-day flight instructors, airplane mechanics and
people who live near general aviation airports. I would likewise expect there
to be no relationship.

Here's something that's known to cause crime: young men. The Baby Boomers were
the largest generation ever, which means between the late 60's (oldest Boomers
entering their late teens) and early 90's (youngest Boomers entering their
30's), there was a particularly large population of young men. This doesn't
explain the entire rise and decline in crime (the Boomers weren't _that_ much
larger than other generations), but it's a better starting place than lead
paint.

[1]
[https://news.ycombinator.com/item?id=16025762](https://news.ycombinator.com/item?id=16025762)

[2]
[http://www.columbia.edu/itc/sipa/envp/louchouarn/courses/env...](http://www.columbia.edu/itc/sipa/envp/louchouarn/courses/env-
chem/Pb-Rise&Fall\(Nriagu1990\).pdf)

[3] [https://ourworldindata.org/wp-
content/uploads/2013/03/homici...](https://ourworldindata.org/wp-
content/uploads/2013/03/homicide-rates-in-the-united-states-1950-2010-and-
canada-1961-2009-pinker-2011-jpg.jpg)

[4]
[http://www.slate.com/content/dam/slate/articles/news_and_pol...](http://www.slate.com/content/dam/slate/articles/news_and_politics/foreigners/2014/12/141209_Charts-
Homicide-Rates-Mex.jpg.CROP.promovar-mediumlarge.jpg)

~~~
taeric
I like the data on gas, though I'm not as sold that you have successfully
ruled out lead paint.

I'm also not sure on your argument for how "young men" cause crime. Where are
you wanting to start, exactly? Do we have numbers that show a higher
population of males in the US than in Canada over that time period?

~~~
smitherfield
_> I'm also not sure on your argument for how "young men" cause crime._

Criminals skew young and overwhelmingly male.[1]

 _> Do we have numbers that show a higher population of males in the US than
in Canada over that time period?_

It appears the baby boom was about the same size or slightly larger in Canada
than the US.[2] As you can see from my first post, there also was an increase
in crime in Canada during the same time period as in the US, but not as
pronounced.

Unlike Corn, who is claiming that leaded gasoline is _the primary_ cause of
crime, such that it explains the entire or nearly the entire late 20th-century
rise and fall in the US crime rate, I am making the much more conservative
claim that the ratio of young men in a population is _a_ cause of crime.

Indeed, as I said, the Baby Boom was not large enough for it to have been _the
primary_ cause of the US crime wave. (Although it _might_ be sufficient to
explain the relatively-smaller Canadian crime wave over the same period).

[1] [https://i.imgur.com/2WscI1P.jpg](https://i.imgur.com/2WscI1P.jpg) — The
chart understates the correlation between youth and crime, because prisoners
might be serving multi-year sentences, they may have got away with other
crimes prior to those they're serving time for, and first-time offenders are
more likely to receive a shorter or no prison sentence than recidivists are.

[2] [https://imgur.com/a/NFLfm](https://imgur.com/a/NFLfm)

~~~
taeric
Ah, I have not fully read this person's claim that lead is _the_ cause for
crime. I have taken a personal liking to the theory, since it at least has
some causal capabilities to it. (Specifically, we know it directly has an
effect on brain chemistry.) So, to that end, I am probably arguing a different
take. Even if I expect it to be a majority parameter, I would also expect at a
local level there will be major variance in how influential it is.

I'm still not sure how your argument is working, though. The size of the baby
boom would be mostly irrelevant, at a major numbers position. Unless you are
arguing there is a saturation point for how many males a population can
sustain, not a percentage that it can sustain. (You specifically claim ratio,
though.)

Which is _not_ to say I am trying to shoot it down. I'm very interested in
exploring the question. My strongest suspicion is that there is something else
we were putting people in contact with. Would be amusing if it was DDT levels
or some such that we know is bad for other reasons and stopped completely.

That said, I fully acknowledge this as a bias of mine. That I suspect it is
not the direct things people think they did that caused something to improve,
but something else that happened to happen at the same time. Lead is
attractive because we know it is terrible for you.

------
RcouF1uZ4gsC
We may have more definitive data in a few years due to Flint, Michigan.

~~~
fisherjeff
Actually, the rise in blood lead levels in Flint in 2014-15 does not seem
likely to create a very large effect:

[http://www.motherjones.com/kevin-drum/2016/01/raw-data-
lead-...](http://www.motherjones.com/kevin-drum/2016/01/raw-data-lead-
poisoning-kids-flint/)

~~~
nwah1
This is great news.

Although, hyper-vigilance on this topic is warranted because there is no safe
dosage of lead, and there's still communities that have high levels in their
water.

[https://www.reuters.com/investigates/special-report/usa-
lead...](https://www.reuters.com/investigates/special-report/usa-lead-
newyork/)

