get the lead out

And that's what we're doing here at the cocktail party. Let's just say it's been a little crazy since March, not just for me but for the rest of my fellow CPP bloggers. But don't abandon us! We're planning a delicious and intoxicating non-stop party for the summer, with lots of posts, designed to make you not even miss Jennifer, our intrepid leader, while she's making the last sprint on finishing her calculus book.

So hey, did you see the new "X-Men Origins" film with Wolverine? And how about that horrifying scene where they dunk the gorgeously half-nekkid Hugh Jackman into what looks like an acid bath and inject his bones with adamantium and he comes up wearing eyeliner and a floppy haircut? Oh wait no. Wrong element. That would be AdamAntium. Never mind. Ba-dum-bum. SSSSSSS.

Oddly enough, when I wasn't thinking of fallen British pop stars or Hugh Jackman's half-nekkid body while watching this scene, I was thinking about . . . lead. And bad puns about Iron Man. No really. Cuz that's the kind of geek I am. See, during my stint with the environmental and hazardous materials engineers, I learned a lot of fun facts about pollutants, of which lead is a major one, especially in urban areas. Stick with me here, and I'll get to the Wolverine connection, I promise. But first, a little about lead.

Lead has been a hidden yet common ingredient in a number of familiar objects and substances for centuries. It was used as piping in the Romans' extensive aqueduct system (more on that later, too), and as an additive to ceramic glazes, where it functions to lower the melting point and enhance colors. It was and is added to crystal (as lead oxide) to give it brilliance and a crisp ringing tone (important if you're playing music on them). Lead was a key component of cosmetics (giving medieval and Renaissance faces that sought-after paleness), home remedies, and condiments, and used as a spermicide and preservative for wine. It was made into tankards, cooking pots, and dishes as well. The Romans also knew it could cause some strange symptoms, which they called "Saturnine gout" because lead was associated with the god Saturn, but that doesn't seem to have stopped them or anyone else from using it.

In the modern world, the two biggest sources of exposure are, or were, lead in gasoline and lead in paint. Lead was clearly recognized as a  health hazard in the U.S. and Europe as early as the 19th century but steps to limit its use, at least in gasoline, were not taken until the 1970s. The nasty truth is that it was actually known that adding tetra-ethyl lead (TEL) was a health hazard at least as early as the1920s, but this evidence was ignored in favor of profitability. Leaded gasoline was finally phased out entirely in 1996 with a few exceptions.

Lead was originally added to gasoline as an "anti-knock" agent, to prevent pockets of air and fuel mixtures from igniting at the wrong time and wrong place in your engine's piston stroke cycle, which it did by controlling the volatility or explosive characteristics of gasoline. The extraneous ignition shock wave causes the pinging or knock, and can be harmless or extremely destructive depending on when it happens in the cycle and how energetic it is. Lead was added to increase the octane of gasoline, or its resistance to detonation. The more resistance, the more efficient the fuel because it only ignites when it's supposed to, i.e., when lit by the spark plug. Although there are a number of anti-knock agents that have far less toxicity, TEL became the additive of choice for a number of complicated reasons, including plain ol' greed. As a result, something like 7 million tons of it were burned during the 20th century, and remain in the soil and water, making our current exposure levels 300-500 times greater than the normal background exposure. As Jamie Lincoln Kitman points out in his lengthy and horrifying article on lead in The Nation, "'Britain's Royal Commission on Environmental Pollution concluded that lead was dispersed so widely by man in the twentieth century that "it is doubtful whether any part of the earth's surface or any form of life remains uncontaminated by anthropogenic [man-made] lead.'"

Yikes!

The introduction of unleaded gasoline cut airborne emissions, but the stuff was still around not only in the soil (leaching into food) and air, but in the gallons and gallons of paint slowly peeling off interior and exterior walls, mixing with dust and becoming airborne or sinking into the soil. Lead is added to paint to increase its durability, color-fastness, and drying speed, and to make it moisture resistant. This latter quality means that lead is still used in paint for industrial purposes, especially ship paint, but it's been banned for use in residential settings. Lead poisoning from paint was (and still is) a huge problem in low-income neighborhoods where the buildings are often old and not well-maintained. When lead paint flakes, children often ingest it in chunks (pretty colors!) or it gets ground up into particulate matter and inhaled. I remember PSAs from my childhood showing a teething toddler gnawing on a flaking windowsill, as kids do, as part of a warning about how easily lead paint can be ingested by children. Lead paint removal has now become an environmental justice issue in many inner city communities, despite initiatives by city governments to mandate its removal in all residential buildings. The removal process is time-consuming and expensive because it must be done using hazmat precautions by trained technicians and involves basically scraping, sanding, ore peeling with heat or chemicals down to the bare surface in most cases. Not cheap or easy.

So what's the problem with lead, anyway? Lead is what's called a heavy metal (no, not that kind, although there may be some headbanging involved if you're poisoned by it). It's kind of a slippery term, but in general, non-scientific usage, it refers to the transition metals: among them, copper, zinc and lead, which are also pretty dense (hence the "heavy" part) and fairly toxic to humans. One of the factors that makes them toxic is their ability to bind to organic molecules and accumulate in tissue, as mercury accumulates in fish, for example.

And here's where the Wolverine connection comes in: Bones have a special affinity for lead, reacting to it by replacing calcium with it, so it stays in the body. In the x-ray at left, the white bands you see above and below the knee of this child are lead deposits, which look eerily like Wolverine's skeleton in the early stages of the adamantium injection. Ew. Lead also winds up in the blood and soft tissues too, like your liver,  heart muscle, and kidneys. The most damaging effect, though, has to do with its interactions with the central nervous system. Because it acts so much like calcium in the body, and calcium is one of the chemicals responsible for electrical activity in your brain, replacing it with lead is a real problem. Basically, it leads to a kind of short circuit, disrupting synaptic connections. In adults, it can produce cognitive deficits, abdominal cramping, constipation, tremors, and mood changes. Poisoning from the TEL put in gasoline is particularly ugly and manifests itself in several ways, including as "a mental disorder suggestive of schizophrenia."  It's also associated with violent behavior, which is not surprising, given the changes in the brain that it causes. What's interesting is that since the ban on leaded gasoline, studies have shown that violent crime has fallen in the countries most affected. The correlation is interesting, but not necessarily conclusive.

In children, whose brains are still developing, it can cause permanent mental retardation, seizure disorders, aggressive behavior, developmental regression, and cerebral edema (brain swelling) leading to seizures, coma, and death. What makes lead so insidious is that it takes a lower concentration of it to mess up your synapses than the concentration of calcium necessary to run them smoothly.

And toys, sadly, have in the past been another delivery system for lead. Many older toys were made from tin or lead and/or used lead paint as well. In the U.S., this is now illegal, but last year, there was a big stink in the media and retail circles about toys manufactured in China which made use of lead-based paint. Mattel, venerable maker of many an action figure (though not our Wolverine; wouldn't that have been ironic?), suffered extreme embarrassment at having to recall approximately 9 million toys it contracted to have manufactured in China, where production standards are not as closely monitored. Many of the recalled toys were in the Fisher Price brand, which is geared toward infants and toddlers, a stage at which kids put just about everything in their mouths, offering an easy conduit for loose chips of lead paint. In response, the Feds developed some stringent rules about product testing intended to protect children from ingesting lead paint.Unfortunately, this turned out to be a real burden on independent toy makers, but that's another story that's still being hashed out. Suffice to say that although there are relatively inexpensive kits to test for lead in your toys or other objects, laboratory-grade testing is beyond the means of most small, cottage-industry-level manufacturers.

Humans aren't the only creatures affected by lead poisoning. One of the more unusual ways to be poisoned by lead (or at least one would think so) is from being shot with lead bullets, but this is exactly what contributed to the death of one California Condor, recently, who was peppered with lead shotgun pellets. And it's not the only kind of run-in with bullets that's been dangerous for the condors. They're scavengers and often dine on shotgunned varmits and deer in their habitat. Once those lead pellets come into contact with the acids in the bird's stomachs, uptake into the system begins and lead poisoning results. So lead bullets have been banned in their habitat, which has apparently made some hunters really unhappy.

Ingesting lead in your food isn't just for condors, either. As I mentioned above, Lead is added to a number of ceramic glazes used on dishes in other countries (it's illegal here, and imported and local dishware that uses it must be marked "not safe for food"). Remember that acid reaction in the condor's stomach? Citric acid (from citrus fruits) has the same effect, as does the acetic acid in grapes, wine, and vinegar, and other acidic foods. Citric and acetic acid are chelating agents, which means they form bonds with metal molecules to produce soluble molecules (which is why they're great for dissolving hard water stains). Once in your body via the food, those molecules break down again and your bones and tissues absorb the lead as above.

But that chelating power can be used for good! Turns out that sprinkling citric acid crystals on fields with, say, radishes can help mitigate or abate the presence of heavy metals in the soil. The citric acid binds with the heavy metals and is drawn up through the roots, where the chemistry of the plants turns it into a less toxic form and sends it into the leafy shoots. This is a process known as phytoremediation and some plants don't even need the citric acid boost because they naturally accumulate heavy metals at a concentration that would poison most. Radishes aren't the usual choice for this job, but they do work pretty well. Sunflower, corn, wheat, and a number of weeds including ragweed also work well. Even better, the metals can usually be recovered from the plant matter. It's nature's recycling process. As remediation processes go, it's not quick, but it's definitely a lot cheaper than soil caps (PDF) or excavation and disposal.

Finally, you may have heard those rumors that lead was responsible for the fall of the Roman Empire because their lead water pipes (like the one at left, running through the bath at Bath) slowly poisoned them all. A geochemist at University of Michigan's School of Public Health, Jerome Nriagu, wrote an interesting article to this effect in the New England Journal of Medicine. It's hardly conclusive, and there are some strong objections to it, one being that flowing water, as long as it's not terribly acidic, is not going to leach much lead out of pipes. But the Romans had some other habits that certainly contributed to the prevalence of "Saturnine gout" among the rich, one of which was boiling down grape must in lead pots. Remember how the lead gets out of the glazes? Same principle here, with highly acidic grapes. There's still a fair amount of argument about the idea, but without forensic samples, we'll probably never know just how much lead Romans ingested in their daily diet.

And wouldn't it be interesting to run a few forensic tests on Wolverine, to see what's leaching into his blood from that new skeleton? Adamantium is a steel alloy whose "properties do not qualify it for any know space on the Periodic Table of Elements," according to its creators. So I wonder if that might not account for some of Wolverine's mood swings? Just sayin'.

Comments

[Jan in CT]

The Romans also used lead acetate as a sweetener in wine. Was this another significant source of lead in their environment?

[Jack Thompson]

I would like top clarify the value of TetraEthyl Lead in the piston engine. TEL acts to prevent detonation of the fuel-air charge during combustion. Steady propagation of a flame front through the mixture until it is all burned takes place on a very short timescale to human perception, taking on the order of a portion of to several milliseconds or so.
During detonation, (or pinging or knocking, all words for varying degrees of the same phenomenon) the combustion process kicks up to propagate at the speed of sound, much faster than the speed of flame front propagation, or it spontaneously explodes.

Higher octane or performance number fuels, partially differentiated by blending of the hydrocarbon cocktail that is gasoline and by the addition of TEL are more resistant to this apparent “explosion” phenomenon, and permit higher overall compression ratios (either by the piston alone or by supercharge plus piston compression) As compression ratio is directly related to Otto cycle efficiency, higher is better. Normal combustion is smooth push, but detonation is an impact phenomenon, which can cause all sorts of havoc. A given engine can be made capable of more power from the same weight/volume if detonation phenomena can be suppressed to allow higher compression.

TEL doesn’t typically play a role in keeping a charge from starting to burn before intended, called pre-ignition, although when the combustion process runs amok, key elements of the combustion chamber particularly the spark plug electrodes, can suddenly become much hotter, bringing about pre-ignition. An aircraft piston engine suffering from heavy detonation may destroy itself in half a minute or so.

On a historical note, TEL and related fuel technology very possibly gave the Royal Air Force the slimmest of performance advantages over the Luftwaffe during the Battle of Britain, a contest that was in question to the very end. The US made enough 100+ octane fuel available to the RAF to give them a 10-15% (100-150 horsepower) advantage in combat. This technological edge increased throughout the conflict, and at the close of the war, the allies were utilizing plentiful fuel with octane/performance number as high as 115-145, while the Axis powers fought the war with ever tightening supplies of 87 octane fuel. Like all technology, this TEL has its obvious nobility and deviltry, depending on the moment, the issues and the circumstances.

Finally, today’s unleaded regular 87 octane automobile gas is largely the hydrocarbon cocktail developed for these WWII aviation fuels, without the TEL. Prior the development of these high performance fuels, gasoline blends without TEL were in the 70 octane range, and TEL was added to get to the mid 80’s.

This could easily become a CPP blog topic on its own. The value of various octane fuels to the motorist and a particular vehicle is not understood by the great majority of fuel and vehicle consumers, because it is complex and it is typically explained incorrectly.

[marvin thalenberg md]

Political note. When banning lead in gasoline came before congress in the 70's, the then Congressman GWH Bush voted against it. If the Ethyl company had prevailed, by now our grandchildren would have difficulty learning to tie their shoelaces.
Continuing in the grand Bush tradition, W Bush replaced the competent researchers on the Lead Advisory council with lobbyists for the lead paint industry . The acceptable levels of blood lead in children had been going down, and were supposed to go from 10 ppm to 5, but that stopped.There are still tens of thousands of inner city kids in the older cities poisoned with lead every year- lower iq's, more aggressive behavior

[Joanna Cerazy]

The impact of lead exposure is so destructive that I have devoted mysalf to raising awareness about its effects. I have co-authored a newly released book, “LEAD BABIES: Breaking the cycle of learning disabilities, declining IQ, ADHD, behavior problems, and autism,” The focus of the book is the explaination as to how lead is hurting our families. LEAD BABIES is an easy read; along with a fascinating scientific perspective, four powerful narratives tie science to everyday life. A comprehensive section describes lead’s “hiding” places in the kitchen, playroom, and medicine cabinet. LEAD BABIES is an important book. It empowers individuals to prevent their families from lead damage. Readers are given the tools to identify, reduce and remove lead from their own homes, routines and activities with a step-by-step lead inventory. As consumers, readers learn what to look for when buying new products.
For more information visit www.nomoreleadbabies.com.
Check our links page; we have a few blogs that contain regularly updated information about how to live a lead-smart life.

[Rob Knop]

I didn't think that *any* alloy had a place on the periodic table....

[marvin thalenberg md]

The lead problem is mostly about lead paint in older buildings. Lead acetate- sugar of lead- is sweet and babies chew paint peelings. It is expensive to test children and test old buildings, and the enforcement program and remediation is spotty. So it is mostly an inner city problem.Older children dont absorb as much, and sources like pottery and toys are very scattered.