Chapter 12 Chapter Ten Kicking the Lead Out

In the late 1940s, a graduate student at the University of Chicago named Claire Peterson (who, despite his surname, was originally an Iowa farm kid) was using a new method of measuring lead isotopes to study Earth's Exact age was final determination.Unfortunately, his rock samples were all contaminated -- and badly so.Lead levels in most samples exceeded normal levels by about 200 times.Years later, Peterson understood that the problem lay with a man in Ohio named Thomas Midgley Jr. Midgley was an engineer by training, and the world would have been a better place if he had remained an engineer.However, he became interested in the industrial uses of chemistry. In 1921, while working for the General Motors Research Corporation in Dayton, Ohio, he studied a compound called tetraethyl lead and found that it greatly reduced the vibration phenomenon known as engine knock.

By the early 20th century, everyone knew that lead was dangerous, but it was still found in various forms in consumer products.Canned food was sealed with lead solder; water was often stored in lead cans; and lead arsenate was used as an insecticide to spray fruit.Lead is even a component of toothpaste tubes.Almost every product adds a little bit of lead to the consumer's body.However, the one with the most opportunities and the longest exposure time is the lead added to gasoline. Lead is a neurotoxin.Excessive levels of lead in the body can irreparably damage the brain and central nervous system.Overexposure to lead can cause a variety of medical conditions, among them loss of vision, insomnia, kidney failure, deafness, cancer, paralysis and convulsions.During an acute attack, people may suddenly have horrible hallucinations, which catch the patient and others by surprise.Typically, this symptom then leads to coma or death.No one wants to let their body intake excessive lead.

Lead, on the other hand, is easy to refine and mine, and extremely profitable to produce on a large scale—tetraethyl lead does prevent engine knocking.So, in 1923, the three largest companies in the United States—General Motors, DuPont, and Standard Oil of New Jersey—established a joint venture called the Tetraethyl Lead Gasoline Company (later referred to as the Tetraethyl Petrol Company), the world's It will produce as much tetraethyl lead as it is willing to buy.As it turns out, the world is in great need.The reason why they call the company "Siyi Company" is because "Siyi" sounds more pleasant, and it does not have the meaning of poison like "lead".

On February 1, 1923, they marketed the name (in more ways than most people know) for public acceptance. Workers on the front lines almost immediately developed symptoms such as unsteady gait and sensory confusion, signs of soon after being poisoned.Four B also implemented a policy of nonchalance and firm denial almost immediately, and it worked well for decades.As Sharon Birch McGrain points out in her history of industrial chemistry, Prometheus in the Laboratory, when a factory employee suffers from incurable hallucinations, the spokesperson has the audacity to "The reason why these people are insane is probably because they worked too hard," De told reporters. In the early days of leaded gasoline production, at least 15 workers died, and countless people fell ill, often seriously.Exact numbers are impossible to know because companies almost always cover up, never disclosing embarrassing leaks, spills and poisonings.However, there were times when it was impossible to suppress the news—notably in 1924, when five production workers died and 35 were permanently disabled in just a few days in a single poorly ventilated premises.

As rumors swirled about the dangers of the new product, Thomas Midgley, the inventor of tetraethyl lead gasoline, decided to give a live demonstration in front of reporters in order to reassure people.While talking about how the company ensures safety, he poured leaded gasoline on his hands and held a beaker of the gasoline to his nose for 60 seconds, constantly claiming that he could do it every day without any harm .In fact, Midgley was well aware of the dangers of lead poisoning: he had suffered a serious illness from too much exposure a few months earlier, and now he would never approach the thing except in front of reporters, whenever possible.

Encouraged by the success of leaded gasoline, Midgley now turned his attention to another technical problem of the era. In the 1920s, refrigerators used poisonous and dangerous gases, which often leaked and were very risky. In 1929, a refrigerator leaked at a hospital in Cleveland, Ohio, killing more than 100 people.Midgley set out to invent a gas that was very stable, nonflammable, noncorrosive, and safe to inhale.With an instinct that almost never regrets doing things, he invented chlorofluorocarbons. Rarely has an industrial product been adopted so quickly and unfortunately. CFCs came into production in the early 1930s and turned out to be used in a thousand applications, from car air conditioners to deodorant sprays.It wasn't until half a century later that people discovered that this thing was eating up ozone in the stratosphere.You will understand that this is not a good thing.

Ozone is a form of oxygen that contains three atoms per molecule instead of the usual two.Its chemistry is a bit odd: It's a noxious substance on the ground, but a beneficial one high in the stratosphere because it absorbs dangerous ultraviolet radiation.However, the amount of beneficial ozone is not very large.Even if distributed evenly in the stratosphere, it would only form a layer about two millimeters thick.That's why it's easily perturbed. Chlorofluorocarbons are also not present in large quantities -- only about one billionth of the entire atmosphere -- but the gas is highly destructive. 1 kg of chlorofluorocarbons can capture and destroy 70,000 kg of ozone in the atmosphere.CFCs are still in suspension for a long time -- a century or so on average -- and continue to wreak havoc.It absorbs a lot of heat.The ability of a chlorofluorocarbon molecule to increase the greenhouse effect is about 10,000 times stronger than that of a carbon dioxide molecule-of course, carbon dioxide itself is also an expert at increasing the greenhouse effect.In conclusion, CFCs may turn out to be pretty much the worst invention of the 20th century in the end.

Midgley would never know this.He was dead long before people realized the destructive power of CFCs. His death itself was also highly unusual.After Midgley became crippled by polio, he invented a mechanical device that used a series of motorized pulleys to automatically lift or turn him over in bed. When the machine was activated in 1944, he became entangled in the rope and suffocated to death. If you're interested in dating things, the University of Chicago in the 1940s is the place to be.Willard Libby is on the verge of inventing radiocarbon dating, which will allow scientists to date bones and other organic remains with a precision that was impossible in the past.By this time, reliable dates were only as far back as the First Dynasty of Egypt - around 3000 BC.For example, no one can say with certainty when the last ice caps retreated, or when the French Cro-Magnons adorned Lascaux Cave in the past.

Libby's method was so versatile that he won the 1960 Nobel Prize for it.This method is based on a recognition that there is an isotope of carbon in living things—named carbon-14. Once the living thing dies, this isotope immediately begins to decay at a measurable rate.Carbon-14 has a half-life of about 5,600 years -- the time it takes for half of any sample to disappear -- so by determining how much a particular sample of carbon has decayed, Libby can effectively date an object -- although is within certain limits.After eight half-lives, only 0.39% of the original radiocarbon remains.This amount is too small to make reliable measurements, so carbon-14 dating is only suitable for objects that are no older than about 40,000 years old.

Interestingly, with the widespread use of this technology, some shortcomings are also increasingly revealed.First, it was found that there was a 3 percent error in Libby's formula for a fundamental component called the decay constant.And by this time thousands of calculations had been performed around the world.Instead of revising every calculation, the scientists decided to keep the inaccurate constant. "So," says Tim Flannery, "you just subtract about 3% from every radiocarbon date you see today." The problem isn't quite solved.It was soon discovered that samples of carbon-14 were easily contaminated by carbon from elsewhere—for example, a small bit of unnoticed vegetation that had been collected with the sample.For samples that are not very old -- samples less than about 20,000 years old -- a little contamination is not always a big deal, while for older samples it can be a serious problem, Because the number of remaining atoms in the statistics is really too small.In the first case, to paraphrase Franconia, it's like having one dollar out of $1,000; in the second case, it's like being out of $2.

Moreover, Libby's approach is based on the assumption that the amount of carbon-14 in the atmosphere, and the rate at which organisms take it up, have remained constant throughout history.But in fact, it's not.We now know that the amount of carbon-14 in the atmosphere varies, depending on how effectively the Earth's magnetic field can redirect cosmic rays;This means that some carbon-14 dates are less certain than others.Among the more uncertain dates is the period around the time when humans first arrived in America.That's one of the reasons why that question is always debated. Finally, and perhaps somewhat surprisingly, calculations can be completely meaningless due to seemingly irrelevant external causes such as the animal's diet.A recent case has sparked widespread and heated debate over whether syphilis originated in the New World or the Old World.Archaeologists in Hull have discovered that monks in the Abbey's graveyard had syphilis.The initial conclusion was that the monks had contracted syphilis before Columbus sailed.However, that conclusion has been questioned, as scientists have found that they ate a lot of fish, which could make their bones look older than they really are.The friar may have had syphilis, but exactly how and when, the seemingly easy-to-solve question, remained unresolved. Since the shortcomings of carbon-14 dating add up to quite a few, scientists have devised other methods to date ancient matter, among them thermoluminescence and electron spin resonance.The former is used to measure the number of electrons remaining in the soil; the latter measures the vibration of electrons by bombarding a sample with electromagnetic waves.But even with the best methods, you can't date anything over 200,000 years old, and you can't date inorganic substances like rocks at all.However, it is of course necessary to determine the age of our planet. The problem with dating rocks is that, at one point, almost everyone in the world lost hope.Had it not been for a determined English professor named Arthur Holmes, the quest might have come to a complete halt. Holmes was heroic both in his overcoming and in his achievements. In the 1920s, just as his career was entering its heyday, geology had fallen out of favor—physics was the hot science of the day and was woefully underfunded, especially in Britain, its spiritual birthplace.For many years he was the only member of the Geology Department at Durham University.To date rocks, he often had to borrow or cobble together equipment.Once, in order to wait for the school to provide him with a simple adding machine, his calculation work was delayed for a year.At times he had to stop academic work altogether in order to earn money to support his family - at one point he opened an antiques shop in Newcastle, and at times he couldn't afford the £5 a year membership dues to the Geological Society. The method used by Holmes in his research work is not complicated in theory, arising directly from the process originally discovered by Ernest Rutherford in 1904, that is, some atoms behave in a predictable way. The ratio decays from one element to another, so this process can be used as a clock.If you know how long it takes for potassium-40 to turn into argon-40, and you measure the amounts of both elements in a sample, you can work out the age of that substance.Holmes' contribution was to date rocks by measuring the rate at which uranium decays into lead, and thus -- he hoped -- the age of the Earth. However, there are many technical difficulties to overcome.Holmes also needed—at least would have been happy to have—an advanced instrument capable of making precise measurements on tiny samples, and we already know that all he had was a simple adding machine.Therefore, he was able to declare with some certainty in 1946 that the Earth had been around for at least 3 billion years, and probably longer.That's quite an achievement.Unfortunately, he once again ran into a huge obstacle: his scientific colleagues were very conservative and refused to acknowledge his achievements.Many people, although willing to admire his method, thought that he had not obtained the age of the earth, but only the age of the materials of which it was composed. Around this time, Harrison Brown of the University of Chicago developed a new method for counting lead isotopes in igneous rocks (that is, rocks formed by heating rather than sedimentation).Realizing that the work was rather tedious, he gave it to a young Claire Peterson as his thesis project.He assured Peterson that using his new method to determine the age of the Earth would be "quite easy."In fact, the work took several years. In 1948, Peterson set out to work on the project.Peterson's work on the age of the Earth smacks of mediocrity in comparison to Thomas Midgley's colorful contributions that kept pushing history forward.For seven years, first at the University of Chicago and later at Caltech (where he moved there in 1952), he toiled in a sterile laboratory, carefully selecting samples of ancient rocks and measuring their lead/uranium levels with precision. Proportion. The problem with dating the Earth is that you need extremely old rocks with crystals of lead and uranium in them that are almost as old as the planet - if the rocks were much younger, they would obviously be younger, As a result, wrong conclusions can be drawn, and really ancient rocks are hard to find on earth.By the late 1940s, no one knew why.In fact, it's inconceivable that it would take until the space age for someone to have a plausible account of what happened to Earth's ancient rocks. (The answer lies in plate tectonics, which we will of course get to.) Peterson, meanwhile, can only figure it out with very limited material.Finally, it occurred to him that he could work around the lack of rocks by using rocks outside the Earth.He turned his attention to meteorites. He made a hypothesis—a visionary one that turned out to be quite correct—that many meteorites are actually building materials left over from the early days of the solar system, and thus retain more or less their original internal chemistry.Date these wandering rocks, and you (closely) date the age of the Earth. Often, however, this is easier said than done.There are not many meteorites, and meteorite samples are not easy to collect.Also, Brown's measurement method is too detail-oriented and needs a lot of improvement.The biggest problem was that Peterson's samples were inexplicably and constantly heavily contaminated with lead in the atmosphere whenever they came into contact with the air.It was for this reason that he ended up building a sterile laboratory—the world's first sterile laboratory, at least according to one source. It took seven years of Peterson's uncomplaining work to collect samples for final testing. In the spring of 1953, he sent samples to Argonne National Laboratory in Illinois.In time, he obtained a new type of mass spectrometer that could be used to discover and measure trace amounts of uranium and lead hidden in ancient crystals.Peterson finally got the results.He was so excited that he drove directly to his boyhood home in Iowa to have his mother take him to the hospital because he thought he was having a heart attack. Shortly thereafter, at a conference in Wisconsin, Peterson announced that the Earth's exact age was 4.55 billion years old (with a margin of error of 70 million years)—a figure McGrain applauds: "It's held up for 50 years." After 200 years of With hard work, the earth finally has an age. Peterson almost immediately turned his attention to the problem of lead in the atmosphere.He was astonished to find that what little was known about the effects of lead on the human body was almost invariably wrong or misleading—not surprising, since 40 years of research on the effects of lead has Each study was fully funded by the manufacturers of lead additives. In one such study, a physician with no specific training in chemical pathology undertook a five-year program. According to the plan, he asked volunteers to inhale or swallow increasing amounts of lead, and then tested their urine and stool.Unfortunately, the doctor also doesn't seem to understand that lead is not excreted as waste, it just accumulates in the bones and blood - which is why lead is dangerous, he has neither examined the bones nor tested blood.As a result, lead was declared to have no health effects. Peterson was quick to confirm that there had been a lot of lead in the atmosphere—in fact, there is still a lot of lead, because the lead never went away—about 90 percent of which came from automobile exhaust pipes, but he couldn't prove it.He needed a way to compare the concentration of lead in the atmosphere today with the concentration in 1923 before tetraethyl lead began to be produced commercially.It occurred to him that ice cores might provide the answer. It is known that in places like Greenland, the annual snow cover is well-defined (due to seasonal temperature differences that cause slightly different colors from winter to summer).Just counting up the layers and measuring the amount of lead in each layer, you can calculate the concentration of lead in the global atmosphere at any time over hundreds or even thousands of years.This insight became the basis for the study of ice nuclei.Many modern climatological research works are based on this foundation. Before 1923, Peterson discovered, there was almost no lead in the atmosphere; since then, lead concentrations have climbed dangerously. Now, getting the lead out of gasoline has become his lifelong quest.To this end, he has frequently criticized the lead industry and its interest groups, often with strong rhetoric. This proved to be a brutal struggle.Siyi Company is a powerful company in the world, with many friends in it. (Its directors included Supreme Court Justice Lewis Powell and the American Geographic Society's Gilbert Grosvenor.) Peterson suddenly found that research funding was either withdrawn or hard to come by.The American Petroleum Institute canceled a contract with him, as did the U.S. Public Health Service, a somewhat neutral government agency. Peterson became an increasingly unfavorable figure for the unit.Lead industry officials kept pressuring Caltech board members to either shut up or fuck off.Jamie Lincoln Kittman wrote in The Nation in 2000 that Four B was said to be willing to pay for a professorship at Caltech "if Peterson could pack up and go ".Paradoxically, he was excluded from an American Research Council panel assigned to investigate the dangers of lead poisoning in the atmosphere, even though he was by then undoubtedly the leading expert on atmospheric lead in the United States. Thankfully, Peterson never wavered.Thanks to his efforts, the "Clean Air Act of 1970" was finally proposed, and in 1986 the sale of all leaded gasoline was stopped in the United States.Lead levels in the blood of Americans dropped by 80 percent almost immediately.However, because lead is a difficult substance to eliminate, the blood lead concentration of every living American today is still about 625 times higher than that of a person a century ago.Atmospheric lead levels continue to increase by about 100,000 tons per year, and in entirely legal ways, mainly from mining, smelting and industrial activities.The US also banned the addition of lead in household paint, as McGrain puts it, "44 years after most European countries".Considering lead's alarming toxicity, it is inconceivable that the United States did not stop using solder lead on food cans until 1993. As for the Fourth B Corporation, it was still developing, although General Motors, Standard Oil, and DuPont no longer had shares in the company. (In 1962, they sold their stake to the Almar Paper Company.) According to McGrain, until February 2001, the Four Bs insisted that "studies have shown that leaded gasoline is harmful to both human health and environment does not pose a threat".On its website, the company's history makes no mention of lead -- or George Midgley -- simply mentioning that the original product contained "a certain chemical mixture." Four B Company no longer produces leaded gasoline, but according to the 2001 company report, the sales of tetra ethyl lead in 2000 still reached 25.1 million U.S. dollars (its total sales were 795 million U.S. dollars), slightly higher than the 24.1 million U.S. dollars in 1999. There was an increase, but down from $117 million in 1998.In its report, the company said it was determined to "maximize the cash income generated by tetraethyl lead despite declining worldwide use".Tetraethyl lead is sold worldwide through an agreement with Oaktel Associates of the United Kingdom. As for the other scourge that George Midgley bequeathed us, CFCs, banned in the US in 1974, are stubborn little devils that have been emitted into the atmosphere before (like from deodorant or hairspray) This stuff is almost certainly still there, eating ozone long after you and I have gone to heaven.To make matters worse, we are still pumping huge amounts of CFCs into the atmosphere every year.More than 27 million kilograms of the stuff, worth $1.5 billion, are still on the market each year, Wayne Biddle said.So, who is producing CFCs?It's us -- that said, many large companies still make this product in their overseas factories.Third world countries will not ban it until 2010. Claire Peterson died in 1995.He did not receive a Nobel Prize for his achievements.Geologists have never been qualified for this.What is even more puzzling is that despite his persistent, altruistic, and increasing achievements over the course of half a century, he has gained little fame, or even much attention.We have reason to believe that he is the most influential geologist of the 20th century.However, who has heard of Claire Peterson?Most geology textbooks do not mention his name.Two recent bestsellers on the history of dating the Earth even misspelled his name. In early 2001, someone wrote a review of one of them in Nature and made another mistake, astonishingly identifying Peterson as a woman. In any case, thanks to the work of Claire Peterson, by 1953 the Earth finally had an age that everyone could live with.The only problem now is that it's older than the world around it.