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Saturday, October 17, 2009

Getting the lead out

Cruising the Net I came across a blog post by Leisure Guy that was derived from a fascinating and informative book, A Short History of Nearly Everything, by Bill Bryson.
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In the late 1940s, a graduate student at the University of Chicago named Clair Patterson was using a new method of lead isotope measurement to try to get a definitive age for the Earth at last. Unfortunately all his samples came up contaminated — usually wildly so. Most contained something like two hundred times the levels of lead that would normally be expected to occur. Many years would pass before Patterson realized that the reason for this lay with a regrettable Ohio inventor named Thomas Midgley, Jr.

Midgley was an engineer by training, and the world would no doubt have been a safer place if he had stayed so. Instead, he developed an interest in the industrial applications of chemistry. In 1921, while working for the General Motors Research Corporation in Dayton, Ohio, he investigated a compound called tetraethyl lead (also known, confusingly, as lead tetraethyl), and discovered that it significantly reduced the juddering condition known as engine knock.

Even though lead was widely known to be dangerous, by the early years of the twentieth century it could be found in all manner of consumer products. Food came in cans sealed with lead solder. Water was often stored in lead-lined tanks. It was sprayed onto fruit as a pesticide in the form of lead arsenate. It even came as part of the packaging of toothpaste tubes. Hardly a product existed that didn’t bring a little lead into consumers’ lives. However, nothing gave it a greater and more lasting intimacy than its addition to gasoline.

Lead is a neurotoxin. Get too much of it and you can irreparably damage the brain and central nervous system. Among the many symptoms associated with overexposure are blindness, insomnia, kidney failure, hearing loss, cancer, palsies, and convulsions. In its most acute form it produces abrupt and terrifying hallucinations, disturbing to victims and onlookers alike, which generally then give way to coma and death. You really don’t want to get too much lead into your system.

On the other hand, lead was easy to extract and work, and almost embarrassingly profitable to produce industrially—and tetraethyl lead did indubitably stop engines from knocking. So in 1923 three of America’s largest corporations, General Motors, Du Pont, and Standard Oil of New Jersey, formed a joint enterprise called the Ethyl Gasoline Corporation (later shortened to simply Ethyl Corporation) with a view to making as much tetraethyl lead as the world was willing to buy, and that proved to be a very great deal. They called their additive “ethyl” because it sounded friendlier and less toxic than “lead” and introduced it for public consumption (in more ways than most people realized) on February 1, 1923.

Almost at once production workers began to exhibit the staggered gait and confused faculties that mark the recently poisoned. Also almost at once, the Ethyl Corporation embarked on a policy of calm but yielding denial that would serve it well for decades. As Sharon Bertsch McGrayne notes in her absorbing history of industrial chemistry, Prometheans in the Lab, when employees at one plant developed irreversible delusions, a spokesman blandly informed reporters: “These men probably went insane because they worked too hard.” Altogether at least fifteen workers died in the early days of production of leaded gasoline, and untold numbers of others became ill, often violently so; the exact numbers are unknown because the company nearly always managed to hush up news of embarrassing leakages, spills, and poisonings. At times, however, suppressing the news became impossible, most notably in 1924 when in a matter of days five production workers died and thirty-five more were turned into permanent staggering wrecks at a single ill-ventilated facility.

As rumors circulated about the dangers of the new product, ethyl’s ebullient inventor, Thomas Midgley, decided to hold a demonstration for reporters to allay their concerns. As he chatted away about the company’s commitment to safety, he poured tetraethyl lead over his hands, then held a beaker of it to his nose for sixty seconds, claiming all the while that he could repeat the procedure daily without harm. In fact, Midgley knew only too well the perils of lead poisoning: he had himself been made seriously ill from overexposure a few months earlier and now, except when reassuring journalists, never went near the stuff if he could help it.

Buoyed by the success of leaded gasoline, Midgley now turned to another technological problem of the age. Refrigerators in the 1920s were often appallingly risky because they used dangerous gases that sometimes leaked. One leak from a refrigerator at a hospital in Cleveland, Ohio, in 1929 killed more than a hundred people. Midgley set out to create a gas that was stable, nonflammable, noncorrosive, and safe to breathe. With an instinct for the regrettable that was almost uncanny, he invented chlorofluorocarbons, or CFCs.

Seldom has an industrial product been more swiftly or unfortunately embraced. CFCs went into production in the early 1930s and found a thousand applications in everything from car air conditioners to deodorant sprays before it was noticed, half a century later, that they were devouring the ozone in the stratosphere. As you will be aware, this was not a good thing.

Ozone is a form of oxygen in which each molecule bears three atoms of oxygen instead of two. It is a bit of a chemical oddity in that at ground level it is a pollutant, while way up in the stratosphere it is beneficial, since it soaks up dangerous ultraviolet radiation. Beneficial ozone is not terribly abundant, however. If it were distributed evenly throughout the stratosphere, it would form a layer just one eighth of an inch or so thick. That is why it is so easily disturbed, and why such disturbances don’t take long to become critical.

Chlorofluorocarbons are also not very abundant—they constitute only about one part per billion of the atmosphere as a whole—but they are extravagantly destructive. One pound of CFCs can capture and annihilate seventy thousand pounds of atmospheric ozone. CFRCs also hang around for a very long time—about a century on average—wreaking havoc all the while. They are also great heat sponges. A single CFC molecule is about ten thousand times more efficient at exacerbating greenhouse effects than a molecule of carbon dioxide—and carbon dioxide is of course no slouch itself as a greenhouse gas. In sort, chlorofluorocarbons may ultimately prove to be just about the worst invention of the twentieth century.

Midgley never knew this because he died long before anyone realized how destructive CFCs were. His death was itself memorably unusual. After becoming crippled with polio, Midgley invented a contraption involving a series of motorized pulleys that automatically raised or turned him in bed. In 1944, he became entangled in the cords as the machine went into action and was strangled.

. . . and what about Clair Patterson, mentioned at the start of this article?

Well, Patterson tackled the nagging question of all that lead in the atmosphere. He was astounded to find that what little was known about the effects of lead on humans was almost invariable wrong or misleading — and not surprisingly, he discovered, since for forty years every study of lead’s effects had been funded exclusively by manufacturers of lead additives.

In one such study, a doctor who had no specialized training in chemical pathology understood a five-year program in which volunteers were asked to breathe in or swallow lead in elevated quantities. Then their urine and feces were tested. Unfortunately, as the doctor appears not to have known, lead is not excreted as a waste product. Rather, it accumulates in the bones and blood — that’s what makes it so dangerous — and neither bone nor blood was tested. In consequence, lead was given a clean bill of health. [But surely he must have realized that, with all that lead going in and none coming out, the volunteers must be accumulating the lead? – LG]

Patterson quickly established that we had a lot of lead in the atmosphere — still do, in fact, since lead never goes away — and that about 90 percent of it appeared to come from automobile exhaust pipes, but he couldn’t prove it. What he needed was a way to compare lead levels in the atmosphere now with the levels that existed before 1923, when tetraethyl lead was introduced. It occurred to him that ice cores could provide the answer.

It was known that snowfall in places like Greenland accumulates into discrete annual layers (because seasonal temperature differences produce slight changes in coloration from winter to summer). By counting back through these layers and measure the amount of lead in each, he could work out global lead concentrations at any time for hundreds, or even thousands, of years. The notion became the foundation of ice core studies, on which much modern climatological work is based.

What Patterson found was that before 1923 there was almost no lead in the atmosphere, and that since that time its level had climbed steadily and dangerously. He now made it his life’s quest to get lead taken out of gasoline. To that end, he became a constant and often vocal critic of the lead industry and its interests.

It would prove to be a hellish campaign. Ethyl was a powerful global corporation with many friends in high places. (Among its directors have been Supreme Court Justice Lewis Powell and Gilbert Grosvenor of the National Geographic Society.) Patterson suddenly found research funding withdrawn or difficult to acquire. The American Petroleum Institute canceled a research contract with him, as did the United States Public Health Service, a supposedly neutral government institution.

As Patterson increasingly became a liability to his institution, the school trustees were repeatedly pressed by lead industry officials to shut him up or let him go. According to Jamie Lincoln Kitman, writing in The Nation in 2000, Ethyl executives allegedly offered to endow a chair at Caltech “if Patterson was sent packing.” Absurdly, he was excluded from a 1971 National Research Council panel appointed to investigate the dangers of atmospheric lead poisoning even though he was by now unquestionably the leading expert on atmospheric lead.

To his great credit, Patterson never wavered or buckled. Eventually his efforts led to the introduction of the Clean Air Act of 1970 and finally to the removal from sale of all leaded gasoline in the United States in 1986. Almost immediately lead levels in the blood of Americans fell by 80 percent. But because lead is forever, those of us alive today have about 625 times more lead in our blood than people did a century ago. The amount of lead in the atmosphere also continues to grow, quite legally, by about a hundred thousand metric tons a year, mostly from mining, smelting, and industrial activities. The United States also banned lead in indoor paint, “forty-four years after most of Europe,” as McGrayne notes. Remarkably, considering its startling toxicity, lead solder was not removed from American food containers until 1993.

As for the other scourge left to us by Thomas Midgley, chlorofluorocarbons, they were banned in 1974 in the United States, but they are tenacious little devils and any that you loosed into the atmosphere before then (in your deodorants or hair sprays, for instance) will almost certainly be around and devouring ozone long after you have shuffled off. Worse, we are still introducing huge amounts of CFCs into the atmosphere every year. According to Wayne Biddle, 60 million pounds of the stuff, worth $1.5 billion, still finds its way onto the market every year. So who is making it? We are — that is to say, many of our large corporations are still making it at their plants overseas. It will not be banned in Third World countries until 2010.

Clair Patterson died in 1995. He didn’t win a Nobel Prize for his work. Most geology textbooks don’t mention him. Two recent popular books on the history of the dating of Earth actually manage to misspell his name. In early 2001, a reviewer of one of these books in the journal Nature made the additional, rather astounding error of thinking Patterson was a woman.
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I think I've discovered a book worth having in my little library, A Short History of Nearly Everything, by Bill Bryson. I'm off for the Oxford Bookstore.

Cheers,
Rockinon

2 comments:

  1. It's a great book! I've read it 3 times, and each time I find an extra little bit that I didn't spot last time. There really is something about everything in there.

    Personally, I love the opening part about how many ridiculous little chemical reactions and coincidences have had to take place simply for "you" to exist at all!

    Enjoy the book.

    ReplyDelete
  2. I have read more books since I started blogging than I previously read in years. This comment from Em has steeled my resolve to find and buy the Bill Bryson book.

    Thank you, Em.

    Cheers,
    Rockinon

    ReplyDelete