[helene_t]

This is a somewhat old (2013) article I just came across - I was aware that the phasing-out of lead in petrol has been linked to rise in IQ. But that it could be one of the major factors in detemining criminal behaviour?

http://www.theguardi...-british-export

Quote

lead levels appeared to explain 90% of the difference in rates of aggravated assault between US cities

Quote

18% of white children but 52% of black children in the US had over 20 milligrammes per decilitre of lead in their blood; another found that, between 1976 and 1980, black infants were eight times more likely to be carrying the horrendous load of 40mg/dl. This, two papers propose, could explain much of the difference in crime rates between black and white Americans

Quote

tetraethyl lead is being exported to Afghanistan, Algeria, Burma, Iraq, North Korea, Sierra Leone and Yemen, countries afflicted either by chaos or by governments who don't give a damn about their people.

The latter could be reverse causation, of course: Governments that don't give a damn about their people are more prone to allow import of tetraethyl lead.

Anyone here who knows about this issue?

[y66]

I don't know anything about this problem except that my wife removed leaded paint from a bathroom years ago and claims she has not been the same since. The Mother Jones story that Monbiot refers to is fascinating. I see that Jessica Wolpaw Reyes continues to research the effects of lead exposure on behavior and educational performance.

[Trinidad]

This week, I saw a documentary about chemistry on the BBC. In it they mentioned that Tetraethyl lead (TEL) (an excellent and cheap antiknocking agent) was removed from car fuel because of the impact of lead on the environment (and health). I was surprised that a chemist would say that in a documentary. Though it was known for quite some time that lead was bad for the environment and health, fuel was not the primary source of human lead intake. (That role was reserved for smoking due to absorbed lead on tobacco leaves.) So direct health concerns were not the motivation to remove lead from fuel.

The primary reason to remove lead from fuel in the 1980's was that cars were emitting too much
NOx (nitrous oxides), leading to acid rain (e.g. devastating the Scandinavian lakes)
CO (carbon monoxide),
hydrocarbons (HCs) (essentially fuel that hadn't combusted properly), causing smog

The solution to this problem was the three-way catalyst. This is a system that kills three birds with one stone: The NOx is used to oxidize the CO and HCs yielding water and carbon dioxide. This completes the combustion reaction to relatively harmless gases (other than the greenhouse effect of the carbon dioxide).

This three-way catalyst consists of narrow tubes that are coated with finely dispersed platinum and rhodium (and a few more, some secret, others less secret, ingredients). The platinum and rhodium, expensive noble metals, are the active material of the catalyst. The surface of the platinum and rhodium is where the reaction takes place. A change in the chemistry of the surface will deactivate the catalyst: The reaction will not occur anymore and catalysts scientists (who generally call "catalysts", "cats" because it is shorter) will say that "the cat is dead".

Most catalysts, including platinum and rhodium based catalysts, as found under your car, are pretty robust: They are immune to many different chemicals. But there are a few elements that are notorious cat-killers: Sulphur and lead are probably topping the list of any catalysis scientist's nightmares.

So, the real motivation why lead was removed from fuel was not because the lead itself was bad for health (it was). It was to make the three-way exhaust catalysts work without killing them in the first 1000 km.

There was an additional problem. The lead did serve two purposes in the fuel.
The first and most obvious was that it was used as an anti-knocking agent (or Octane-booster). It increased the Octane number of the fuel. There were other (though more expensive) compounds available that could replace this function of tetraethyl lead, such as MBE (Methyl Butyl Ether). So, that could be solved (with an increase in the gas price).
The second function of the lead was to lubricate the engine valves. There was no alternative fuel additive that could achieve this. This meant that the engines needed to be redesigned: the material for the valves needed to be made harder and friction needed to be reduced. This is why some old cars still need some leaded fuel.

So for the phasing out of lead from fuel one big environmental issue (acid rain) and two technical developments (the three-way catalyst and the new engine valve systems) were needed. Direct health issues had little to do with it (and lead in fuel was not the largest contributor to lead in humans anyway).

Rik

[billw55]

While environmental lead poisoning is certainly a serious public health concern, I would be very skeptical about a causal connection with crime rates, or racial disparities in crime rates.

I have also read speculation that legalization of abortion in the 70s was a causal factor in the crime rate decline beginning in the 90s. Argument thus: crime is correlated with poverty; poverty is often generational; poor women/girls are more likely to want and get abortions; ergo, an increased tendency for future criminals to be aborted. I am pretty skeptical about that one too.

[helene_t]

Trinidad, on 2015-April-06, 08:01, said:

fuel was not the primary source of human lead intake. (That role was reserved for smoking due to absorbed lead on tobacco leaves.)

Intersting. Do you have a source?

But when you say that tobaco was the main source of lead in the blood, do you mean lead in adult blood or children's blood or overall?

By the way, isn't it so that lead in tobaco comes from lead in the atmosphere which in turn comes from petrol?

[barmar]

Why does it matter whether it's the primary source or not? As long as it's a non-negligible source, getting rid of it should be a health benefit.

I also remember when lead in house paint was banned, because kids would eat peeling paint from the walls. This was probably also mostly an issue in low-income areas -- I don't remember seeing much peeling paint in my middle-class home.

[billw55]

barmar, on 2015-April-06, 09:12, said:

Why does it matter whether it's the primary source or not? As long as it's a non-negligible source, getting rid of it should be a health benefit.

I also remember when lead in house paint was banned, because kids would eat peeling paint from the walls. This was probably also mostly an issue in low-income areas -- I don't remember seeing much peeling paint in my middle-class home.

You are right. Lead paint is an exposure risk, primarily for small children. Yes, it is correlated with poverty, due to several factors including generally older and poorly maintained housing, access to health care, malnutrition, etc. The latter two apply regardless of the source of exposure, of course.

[Trinidad]

helene_t, on 2015-April-06, 08:47, said:

Intersting. Do you have a source?

This was all stuff from he 1980's. So, I don't have any sources. I was an undergraduate in Chemical Engineering at the time and did several projects on Tetra Ethyl Lead and fuel. (We had a mandatory group project "Chemistry and Society". This took an afternoon per week of instructor contact for an entire year. We chose Lead in Fuel, since it was hot at the time (1984) in the Netherlands: The Kuwait Petroleum Company (Q8) was the first one to introduce lead free fuel on the market there, under the brand name 2048.

We studied quite a bit of literature. I would not claim that our work at the time was of top scientific level, bit I'ld like to think that we were quite thorough. (We got excellent grades, at least.)

So most of the "politico-social background" comes from those days from my memory and, obviously, I have followed the developments there.

Later in my career, I specialized in catalysis. Then the story of the three-way catalyst is mandatory knowledge, because it is the connection of the world of science to the man in the street. Whenever you need to explain what kind of work you do, you need an example of an application that an interested layperson might have heard of. The catalyst in the car is the obvious example.

Now, I am a surface scientist: I look specifically at the outermost layer of atoms of a material. This is important in catalysis, since the reaction happens at the surface of the catalyst where the gas can be in contact with it. But it is also important in many other fields, such as layer growth (e.g. semiconductors are grown one layer of atoms at the time!), adhesion (How do you make the paint stick to a rubber car bumper? Try to paint some piece of plastic at home without it chipping off in 2-3 days.), friction (wear), biology (How do chemical compounds (food, medication, poison enter a cell?), pharma, etc...

Meanwhile, I am not active in all the other aspects of catalysis anymore (catalyst design, catalytic reactor engineering, etc.). So I don't look at the 50 m scale of catalytic reactors in an oil refinery or chemical plant, or on the 30 cm scale of a three-way catalyst in a car. I look at what happens on the 0.2 nm scale: the thickness of 1 layer of atoms.

helene_t, on 2015-April-06, 08:47, said:

But when you say that tobaco was the main source of lead in the blood, do you mean lead in adult blood or children's blood or overall?

I really don't know.

helene_t, on 2015-April-06, 08:47, said:

By the way, isn't it so that lead in tobaco comes from lead in the atmosphere which in turn comes from petrol?

No!! I should have mentioned that immediately. The lead on tobacco leafs comes from natural sources: It comes from the natural radioactive decay of radon gas. (Simply put: Radon -> lead + 2 alpha particles). And apparently tobacco leafs are pretty good at adsorbing lead.

Remember that tobacco is grown in Kentucky, not in L.A.

Rik

[billw55]

Trinidad, on 2015-April-06, 10:03, said:

No!! I should have mentioned that immediately. The lead on tobacco leafs comes from natural sources: It comes from the natural radioactive decay of radon gas. (Simply put: Radon -> lead + 2 alpha particles). And apparently tobacco leafs are pretty good at adsorbing lead.

This sounds peculiar. Naturally occurring (i.e. primordial) lead in the soil should be much greater than that created through radioactivity. OK, radon is a gas, so it can become airborne and then later deposit on the leafs. But this still sounds like a trace process to me. If this was really significant, wouldn't we have lead accumulating on surfaces all over the great lakes and Appalachia regions - including on crops? Plus it will rain from time to time .. it just doesn't sound likely to me.

If lead is present in cigarettes at significant levels, I would suspect it was in an additive - much like gasoline.

[Trinidad]

billw55, on 2015-April-06, 10:35, said:

This sounds peculiar. Naturally occurring (i.e. primordial) lead in the soil should be much greater than that created through radioactivity. OK, radon is a gas, so it can become airborne and then later deposit on the leafs.

Are you aware that there are areas that are not inhabitable due to the amount of radioactive radon gas escaping from rocks? (I used to live in Sweden in an area where radon testing was performed routinely.)

I am certainly not an expert on tobacco. And I remember that at the time, I also found it peculiar. But the explanation I read back then:
Tobacco leafs are somewhat sticky. And tobacco is grown in areas with high concentrations of radon.
The tobacco leafs apparently specifically adsorb lead, leading to an accumulation of lead.
After harvesting, the tobacco is dried, increasing the lead concentration significantly. (I would say by an order of magnitude.)
When the tobacco is smoked, the lead is inhaled as an organometallic compound. These compounds are volatile.

So, there are several steps that lead to an increase in the lead concentration. Furthermore, it is good to remember that we are talking about the effects of very low levels of lead to begin with. Lead in fuel or lead paint or lead from tobacco doesn't lead to grams of lead in our blood (fortunately). The amounts needed for health effects are small.

In addition, it is very easy to determine whether the lead comes from the soil or from radioactive decay. The isotope pattern of the lead will be different in the two cases. I will readily admit that I don't remember those details from 30 years back, and my knowledge of chemistry at the time was still small, so I might not have understood at the time how they determined that it came from radon. But I do remember that the authors of several articles I read at the time all pointed to radon as the source. With my current knowledge of the scientific process, I would find it hard to believe that articles get published, making such claims, without backing them up with a very simple analysis. (I would be able to do the analysis in my lab in about an hour and we are definitely not specialized in this kind of stuff. For a lab that devoted its research to these issues this would be absolutely routine. They could run hundred of these samples per day.)

The crucial difference between tobacco on the one side and lead paint and car fuel on the other is that tobacco is actually consumed by people: pretty much all the lead in tobacco (even if it contains a small amount) will end up in the body. Few people are drinking lead paint or car fuel. The fact that the lead from tobacco is inhaled as an organometallic compound makes it particularly dangerous: This is an efficient way for the body to take up the lead (or other metals). Eating the lead as lead oxide (on cooked broccoli or a leaf of lettuce) is less effective.

And yes, the deposition of lead from car fuel onto crops was starting to be a problem in densely populated areas around 1980. People had been pushing to reduce lead in car fuel for that reason. But there were other sources of lead that were more dangerous (such as tobacco) and deserved priority. The general lead discussion was "overtaken" at high speed by the acid rain problem in Europe. Around 1980 it was adamant that NOx emissions were reduced (and traffic was the number one source of NOx, by far). This forced the development of the three-way catalyst and, as a consequence, the development of lead free fuel (and engines that could run on it). If I remember correctly, Honda was the first to bring a car to the market that could run on lead free fuel.

Rik

[billw55]

Yes Rik. I am an environmental consultant by profession, and a licensed radon tester in my state. So I do know some things about radon, lead, and environmental exposure. And I am still skeptical about that particular route (radon from soil --> lead deposits on leaf --> inhaled while smoking).

As another point, the half life of 222Rn is 3.8 days, this is many times long enough for thorough mixing in the atmosphere. I can hardly imagine surface deposition of decay products localized to a tobacco field.

Again, not saying those coffin nails lack lead. Just saying that if it is there, it would make sense to seek another source, IMO.

However, this is easily tested. If the lead is from the 238U series, it will be 210Pb, which has no other source. You should also be able to detect some 210Po - which is much nastier than the lead. Can you confirm this from your source?

[billw55]

Fascinating. I looked up a couple things and found myself surprised. From the wikipedia page on Polonium:

Quote

Polonium-210 in tobacco contributes to many of the cases of lung cancer worldwide. Most of this polonium is derived from lead-210 deposited on tobacco leaves from the atmosphere; the lead-210 is a product of radon-222 gas, much of which appears to originate from the decay of radium-226 from fertilizers applied to the tobacco soils.^{[47][109][110][111][112]}

The presence of polonium in tobacco smoke has been known since the early 1960s.^[113][114] Some of the world's biggest tobacco firms researched ways to remove the substance—to no avail—over a 40-year period but never published the results.^[47]

So it seems I underestimated this exposure route. I admit I remain baffled by the deposition from the air. If the source is radium in the fertilizer, then I would think that normal biological uptake into the plants would contribute much more than surface deposition from the air. But perhaps my sense of this is wrong. I find that I must retract my prior skepticism, with apologies to Rik.

In any case, the 210Po must be a greater health hazard than the 210Pb. With a half life of 22 years, 210Pb will remain in the cigarettes for a long time, and consequently so will 210Po, in radioactive equilibrium. (Although, having been wrong already, perhaps I should reconsider, and the lead may be comparably dangerous).

TLDR: stop smoking.

[Cyberyeti]

billw55, on 2015-April-07, 09:16, said:

TLDR: stop smoking.

TLDR: don't start smoking

[Trinidad]

billw55, on 2015-April-07, 09:16, said:

I find that I must retract my prior skepticism, with apologies to Rik.

No need to apologize. In general, skepticism is very healthy when someone claims some truths based on his own memory without providing some independent sources. (Obviously, the report we wrote was typed on a type writer and handed in. It is not like I have it filed somewhere electronically to look it up.)

Anyway, I find it nice to know that I seemed to be able to remember details of things that I did over 30 years ago. I will see how I can use this to my advantage to encourage my kids (who don't even know what a type writer looks like) to study harder.

Rik

[jdeegan]

Working in the corporate planning department of Exxon in the late 1960's, the only thing we knew for sure was that lead in petrol fouled catalytic converters (CC's). Without CC's the automakers would have been unable to meet already mandated exhaust emission standards.

Everything else was just for public relations purposes. We promoted it as long as it supported the basic idea to 'get the lead out'. This is not to say most of this stuff wasn't true. Even then, it seemed pretty clear that getting lead in your system was not healthy.

The whole thing worked out fairly well in a muddling through sort of way. Curiously, most of today's small, turbocharged, high rpm, auto engines using computer chips for control purposes don't need CC's to meet exhaust emission standards.

[billw55]

jdeegan, on 2015-April-20, 08:20, said:

Working in the corporate planning department of Exxon in the late 1960's, the only thing we knew for sure was that lead in petrol fouled catalytic converters (CC's). Without CC's the automakers would have been unable to meet already mandated exhaust emission standards.

Interesting. With EPA established in 1970, I would not have expected exhaust mandates to exist in the 1960s. Learn something new very day.

[jdeegan]

billw55, on 2015-April-20, 09:38, said:

Interesting. With EPA established in 1970, I would not have expected exhaust mandates to exist in the 1960s. Learn something new very day.

After the publication of The Silent Spring in 1962, major institutions with so very much at stake and such amazing resources were determined to be at the forefront, right, wrong or indifferent. You really had to be there to appreciate the emotional climate. Even in 1970 Exxon was funding MIT research on global warming. They simply wanted to be the first to know.

Exxon and their allies write the regs.

[mike777]

yes silent spring resulted in

1) many wanting to stop death and feel good about it
2) many more died.

silent spring huge book that many many feel so good about and yet so many died
even today this book is used to justify so many dead but people think so many live.l

you will find vast people who think this book saved lives rather than killed them.

so many if not most love this book they love this book.

thus you have debate.....if you love this book,.debate is over and silly

I repeat if you love this book, then debate is over and rest is silly.

[jdeegan]

mike777, on 2015-April-21, 02:25, said:

It's OK Mike. Tomorrow will be a better day.