Clair Cameron Patterson
|
|
Clair Cameron Patterson (1922 - 1995) was a geochemist born in Iowa, United States.
Patterson developed the uranium-lead dating method and, based on lead and uranium isotopic data from the meteorite Canyon Diablo, calculated an age for the Earth of 4.55 billion years.
Patterson had first encountered lead contamination when in the late 1940s as a graduate student at the University of Chicago. While using a new method of lead isotope measurement to measure the age of the Earth, he found his rock samples to be contaminated. This contamination was then a mystery.
Estimate of the Earth's age
Harrison Brown of the University of Chicago later developed a relatively newer method for counting lead isotopes in igneous rocks, and assigned it to Patterson as a dissertation project in 1948. During this period he operated under the assumption that meteorites are left over materials from the creation of the Solar System, and thus by measuring the age of one of these rocks the age of the Earth would be revealed. Gathering the materials required time, and in 1953, he had his final specimens. He took them to the Argonne National Laboratory. There he was granted time on a late model mass spectrograph. Purportedly, he was so excited with the results that he drove home to Iowa and had his mother check him into the hospital, since he thought he was having a heart attack.
In a meeting in Wisconsin soon afterward, Patterson revealed the results of his study. The definitive age of the Earth is 4,550 million years (give or take 70 million years). At the time of this writing, this number still stands.
Campaign against lead poisoning
After the completion of this work, Patterson immediately returned to the problem of his initial experiment and the contamination he found. He determined that the cause of the contamination was the use of tetra-ethyl lead to reduce engine 'knock' in internal combustion engines, as well as many other areas in which lead was used. In the early 1900s, lead was used even for soldering tins of food shut.
Beginning in 1965 with the publication of Contaminated and Natural Lead Environments of Man, Patterson tried to draw public attention to the problem of contamination of the environment and the food chain with lead from industrial sources.
In this effort, he fought against the lobbying power of the Ethyl Corporation with all its influence (and the legacy of Thomas Midgley, which included tetra-ethyl lead and chlorofluorocarbons) and the lead additive industry as a whole, to ensure that lead was removed from gasoline (petroleum). In A Short History of Nearly Everything, author Bill Bryson alleges that, because of the influence of the lead industry, Patterson was excluded from a 1971 National Research Council panel on atmospheric lead contamination.
Eventually, Patterson's efforts lead to the Clean Air Act of 1970, and ultimately the removal of lead from all gasoline in the United States by 1986. Reputedly, lead levels within the blood of Americans dropped by 80% soon after this.
Further Reading
- Patterson, C. (1956) "Age of meteorites and the Earth" Geochimica et Cosmochimica Acta 10, 230-237
- Patterson, C. (1965) "Contaminated and natural environments of man" Arch. Environ. Health 11, 344-360
- Bryson, W. (2003) "A Short History of Nearly Everything", 193-255
- Clair Cameron Patterson by George R. Tilton (http://www.nap.edu/html/biomems/cpatterson.html)de:Clair Cameron Patterson