New Zealand Study Provides More Support for Lead-Crime Hypothesis | Hacker News Reader

New Zealand Study Provides More Support for Lead-Crime Hypothesis

motherjones.com

103 pointscurtis36 comments

The title draws the opposite conclusion of the paper itself (https://jamanetwork.com/journals/jamapediatrics/fullarticle/...):

> 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.

> 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.

I actually appreciated the article offering another conclusion as the author did clearly indicate the originals papers conclusion. This isn't the first time papers using data from this study(https://dunedinstudy.otago.ac.nz/) has lead(excuse my pun) to controversial conclusions.

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.

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.

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.

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/

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.

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.

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/

> 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.

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.

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.

It’s worth noting Drum’s actual position on The Bell Curve: http://www.motherjones.com/kevin-drum/2017/05/charles-murray...

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.

It's an entirely fair reading of many of his supporters, who are absolutely about rehabilitating failed social programs.

You got it 180degrees off. Drum is the opposite stereotype from the one you put forth.

> and The Bell Curve not getting a fair hearing

If you put that line at the beginning of your comment you'd saved me a couple of seconds reading.

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.

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.

As I understand it lead paint in the US was a scourge in poor neighborhoods. Old lead paint tends to flake and small children love the taste of lead paint chips because it tastes sweet. 1950-1970's lead paint was a huge issue in poor neighborhoods.

Point I'd make is, often you see people trying or use epidemiological studies to try and prove some cause and effect. And this doesn't actually work very well. The world is filled with associations that have nothing to do with each other. However with lead the neurotoxic effects are fairly well understood in detail. As well as population exposure rates. So in this case epidemiological studies are confirming what one might well expect. Lead exposure ->

This study does record details such as income and economic status over the lifetime of the participants, so in theory you might be able to control for those effects. But the sample size is not huge, and there is a risk of overfitting.

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?

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

That would be easy to check to looking at employment history.

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?

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.

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.

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.

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

[2] http://www.columbia.edu/itc/sipa/envp/louchouarn/courses/env...

[3] https://ourworldindata.org/wp-content/uploads/2013/03/homici...

[4] http://www.slate.com/content/dam/slate/articles/news_and_pol...

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?

>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 — 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

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.

That chart shows time increasing since 2008. When did Mexico ban lead gasoline?

1998, but in practice from the early 90's because leaded gasoline is incompatible with catalytic converters. Leaded gas was banned in 1996 in the US, but in practice disappeared by the early 80's (catalytic converters were mandatory on new US cars from 1975). Most cars sold in Mexico are used American cars, which is the reason for the lag.

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

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-...

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...

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