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He obtained much cleaner laboratory facilities in the new Institute for Nuclear Studies building, where he worked on improvement of analytical techniques. However, after a year this was interrupted when Brown accepted a faculty appointment at the California Institute of Technology. Patterson accompanied him there and built facilities that set new standards for low-level lead work. By he was finally able to carry out the definitive study, using the troilite sulfide phase of the Canyon Diablo iron meteorite to measure the isotopic composition of primordial lead, from which he determined an age for the Earth.

The chemical separation was done at CalTech, and the mass spectrometer measurements were still made at the University of Chicago in Mark Inghram's laboratory.

'Cosmos' Recap: What Lead Poisoning and Earth's Age Have in Common

Harrison Brown's suspicion was finally confirmed! The answer turned out to be 4. The new age was substantially older than the commonly.

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Patterson's reactions on being the first person to know the age of the Earth are interesting and worthy of note. True scientific discovery renders the brain incapable at such moments of shouting vigorously to the world ''Look at what I've done!


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Now I will reap the benefits of recognition and wealth. There "we" refers to what Patterson calls "the generations-old community of scientific minds. To him it must have been an exercise in improving the state of the "community of scientific minds. The age that Patterson derived has stood the test of time, and is still the quoted value forty-four years later.

Clair Cameron Patterson

In the meantime, there have been small changes in the accepted values for the uranium decay constants, improvements in chemical and mass spectrometric techniques, and a better understanding of the physical processes taking place in the early solar system and Earth formation, but these have not substantially changed the age Patterson first gave to us.

Some textbooks have given diagrams showing that the logarithm of the supposed age of the Earth plotted against the year in which the ages appeared approximated a straight line, but Patterson's work has finally capped that trend.

Patterson next focused on dating meteorites directly instead of inferring their ages from the Canyon Diablo troilite initial lead ratios. He did this by measuring lead isotope ratios in two stone meteorites with spherical chondrules chondrites and a second stone without chondrules achon-.

A colleague, Leon Silver, had recommended the achondrite because of its freshness and evolved petrologic appearance. They also fit the 4. The meteorite work led indirectly to his second major scientific accomplishment. The new ability to isolate microgram quantities of lead from ordinary rocks and determine its isotopic composition had opened for the first time the path for measuring lead isotopes in common geological samples, such as granites, basalts, and sediments. That led him to start lead isotope tracer studies as a tool for unraveling the geochemical evolution of the Earth.

As part of that project he set out to obtain better data for the isotopic composition of "modern terrestrial lead" by measuring the isotopic composition of lead in ocean sediments. By Tsaihwa J. Chow and Patterson reported the first results in an encyclopedic publication that initiated Patterson's concern with anthropogenic lead pollution, which was to occupy much of his attention for the remainder of his scientific career. The isotope data revealed interesting patterns for Atlantic and Pacific Ocean leads that could be related to the differences in the ages and compositions of the landmasses draining into those oceans.

However, in studying the balance between input and removal of lead in the oceans, the. Thus, the geochemical cycle for lead appeared to be badly out of balance. The authors noted that their calculations were provisional; the analytical data were scarce or of poor precision in many cases, however this was the seminal study that started Patterson's investigations into the lead pollution problem.

The limitations in the analytical data on which many of the conclusions in the paper were based led Patterson to start new investigations to attack the problem. In he published a report with Mitsunobu Tatsumoto showing that deep ocean water contained 3 to 10 times less lead than surface water, the reverse of the trend for most elements e.

This provided new evidence for disturbance in the balance of the natural geochemical cycle for lead by anthropogenic lead input. In the paper entitled "Contaminated and Natural Lead Environments of Man," 2 Patterson made his first attempt to dispel the then prevailing view that industrial lead had increased environmental lead levels by no more than a factor of approximately two over natural levels. He maintained that the belief arose from the poor quality of lead analyses in prehistoric comparison samples in which much of the lead reported was actually due to underestimation of blank contamination.

He compiled the amounts of industrial lead entering the environment from gasoline, solder, paint, and pesticides and showed that they involved very substantial quantities of lead compared to the expected natural flux. He estimated the lead concentration in blood for many Americans to be over times that of the natural level, and within about a factor of two of the accepted limit for symptoms of lead poisoning to occur. He called Patterson's conclusions "rabble rousing.

Patterson's reactions are recorded in a letter to editor Katharine Boucot accompanying the revised manuscript:. The enclosed manuscript does not constitute basic research and it lies within a field that is outside of my interests. This is not a welcome activity to a physical scientist whose interests are inclined to basic research.

My efforts have been directed to this matter for the greater part of a year with reluctance and to the detriment of research in geochemistry. In the end they have been greeted with derisive and scornful insults from toxicologists, sanitary engineers and public health officials because their traditional views are challenged.

It is a relief to know that this phase of the work is ended and the time will soon come when my participation in this trying situation will stop.


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  8. Patterson's participation did not stop; instead on October 27, , he wrote to California Governor Pat Brown restating the points from his review and emphasizing the dangerously high levels of lead in aerosols, particularly in the Los Angeles area. In it he claimed that the California Department of Public Health was not doing all it should to protect the population from the dangers of lead poisoning.

    His first request drew a polite rejection. A second letter on March 24, , had better success, perhaps because of a letter from a high state official. He had simultaneously started parallel actions at the national level as well. In it he offered to appear before the committee. He was subsequently invited to a hearing held on June 15, , in Washington.

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    There Patterson emphasized that most officials failed to understand the difference between "natural" and "normal" lead body burdens, the former based on incorrect data from pre-industrial humans, the latter on averages in modern populations. In support of that assertion he cited his newer work in Greenland showing the large increases in lead in snow starting with the industrial revolution.

    He furthermore believed it was wrong for public health agencies to work so closely with lead industries, whom he considered often biased in matters concerning public health. His views drew support from some of the public e. Kehoe, the highly regarded authority on industrial poisoning. A battle line was drawn that was to last about two decades. By Patterson and his colleagues had completed studies of snow strata from Greenland and Antarctica that showed clearly the increase in atmospheric lead beginning with the industrial revolution in both regions.

    Modern Greenland snow contained over times the amount of lead in preindustrial snow, with most of the increase occurring over the last years. The effect was about ten times smaller in Antarctic snow, but it was clearly observable. Later work with improved blanks reduced that figure to two. The panel was widely accused of not being forceful enough in interpreting its data and being too heavily weighted toward industrial scientists.

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    Thus was the beginning of the removal of lead from gasoline. Meanwhile Patterson continued to work on the lead problem from another perspective by measuring lead, barium, and calcium concentrations in bones from year-old Peruvian skeletons.

    Clair Cameron Patterson | Biographical Memoirs: V | The National Academies Press

    In a letter Patterson once said, "I have a passionate interest in this paper. In the late s Patterson turned his attention to lead in food. In he wrote to the commissioner of food and drugs at the Environmental Protection Agency asserting that "your headquarters laboratory cannot correctly analyze for lead in tuna fish muscle. When asked if he could cite other laboratories that agreed with his results, Patterson responded that scientific matters are not decided by majority vote.

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    Patterson made three recommendations for improvements that seem to have been taken seriously. A few months later Patterson wrote that he believed the analytical work being done at the headquarters EPA laboratory met his standards. In Dorothy M. Settle and Patterson 15 published a warning on the amount of lead entering the food chain due to lead solder used in sealing cans. Although the National Marine Services laboratories had reported only twice as much lead in canned albacore muscle as in fresh tuna versus nanograms per gram , the authors found 0.

    Barium varied by only a factor of two in the samples. A sample of fresh muscle prepared at CalTech and analyzed at the fisheries laboratory gave 20 nanograms per gram for lead, still much higher than the CalTech value.