Clair Cameron Patterson

Clair Cameron Patterson (June 2, 1922 – December 5, 1995)

He was born in Mitchellville, Iowa. His father was a mail carrier and his mother was a member of the school board; Patterson had one brother, Paul, and one sister, Patricia.^[1][2] From a young age he was encouraged by his family to pursue his intellectual curiosity.^[2] Patterson graduated from high school in 1939, at the age of 16. He attended Grinnell College—close enough that Patterson would hitchhike home to do laundry^[2]—and graduated with a degree in chemistry in 1943.^[1][3] There, he met his future wife, Lorna (Laurie) McCleary. For graduate school, they both attended the University of Iowa, where he was awarded an M.A. in molecular spectroscopy. He also married Lorna McCleary just before leaving the University of Iowa in 1944.^[4] Both were then sent to work on the Manhattan Project as civilians, first at the University of Chicago and then at Oak Ridge, Tennessee, where he encountered mass spectrometry.^[4][5]

After World War II, the Pattersons returned to Chicago, where Laurie took a research job as an infrared spectroscopist to support Patterson while he studied for his Ph.D. at the University of Chicago under Harrison Brown. While studying at an old laboratory, Patterson was able to make discoveries involving the lead that he ended up studying later in his life. He made several different experiments which led to shocking results for the time period involving the lead.^{[further explanation needed][6]} After a postdoctoral year at Chicago, Patterson moved with Brown to the Division of Geology (later the Division of Geological and Planetary Sciences) at the California Institute of Technology in 1952, as founding members of its geochemistry program.^[4] Patterson remained at Caltech for the rest of his life. He and Laurie had four children.^[7]

Measurement of the Earth's age

Patterson returned to the University of Chicago to work under his research adviser

As Patterson and Tilton began their work in 1948, Patterson quickly became aware that his lead samples were being contaminated. They knew the age of the igneous rock from which the zircon came, and Tilton's uranium measurements aligned with what should be in a zircon at that particular age, but Patterson's data always was skewed with too much lead.[8] After six years, the team published a paper on methods of determining the ages of zircon crystals and Patterson earned his Ph.D., but they were no closer in determining the age of the Earth.^{[citation needed]}

Brown was able to receive a grant from the

Before the major discovery was made, it was believed by the public that the earth was around 3.3 billion years old. Many were very surprised to find that the actual age of the earth was much more than what they had expected. The publicity that came after the discovery was made was handled quite well by Patterson, who made the statement, "we did it" in several interviews, sharing the honor of the discovery with his fellow scientific minds behind the action.[13]

Tracing geochemical evolution of Earth

Patterson's ability to isolate microgram quantities of lead from ordinary rocks and to determine their isotope composition led him to examining the lead in ocean sediment samples from the Atlantic and the Pacific. Deriving from the different ages at which the landmasses had drained into the ocean, he was able to show that the amount of anthropogenic lead presently dispersed into the environment was more than 100 times the amount naturally leached by streams into the ocean:^[14] the geochemical cycle for lead appeared to be badly out of balance.

The limitations of the analytic procedures led to his use of other approaches. He found that deep ocean water contained up to 20 times less lead than surface water,^[8] in contrast to similar metals such as barium. That led him to doubt the commonly held view that lead concentrations had grown by only a factor of two over naturally occurring levels.^{[citation needed]}

Patterson returned to the problem of his initial experiment and the contamination he had found in the blanks used for sampling. He determined, through ice-core samples from

Beginning in 1965, with the publication of Contaminated and Natural Lead Environments of Man, Patterson tried to draw public attention to the problem of increased lead levels in the environment and the food chain from lead from industrial sources. Perhaps partly because he was criticizing the experimental methods of other scientists, he encountered strong opposition from those then recognized as experts, such as Robert A. Kehoe.^[8]

In his effort to ensure that lead was removed from

The United States mandated the use of unleaded gasoline to protect catalytic converters in all new cars starting with the 1975 model year,^[16] but Patterson's efforts accelerated the phaseout of lead from all standard, consumer automotive gasoline in the United States by 1986. Lead levels within the blood of Americans are reported to have dropped by up to 80% by the late 1990s.^[17]

Most people, following Kehoe's arguments, referred to "normal levels" of lead in blood, soil, and air, meaning values near the average. They assumed that because these levels were common, they were harmless. "Normal" also carries some of the meaning "natural". Patterson argued that "normal" should be replaced by "typical" and that just because a certain level of lead was commonplace, it did not mean it was without harm. "Natural", he insisted, was limited to concentrations of lead that existed in the body or environment before contamination by humans, which has occurred frequently due to technological advancements and cultural traditions.^[8]

Due to his ultraclean chamber, considered one of the first clean rooms, his measurements of isotopic ratios were free of the contamination that confounded the findings of Kehoe and others. Where Kehoe measured lead in "unexposed" workers in a TEL plant and Mexican farmers, Patterson studied mummies from before the Iron Age and tuna raised from pelagic waters.^[8] Kehoe claimed that humans had adapted to environmental lead. Patterson's precise point was that humans only recently had increased their concentration of lead and that the short span of exposure, a few thousand years, was an instant in the Darwinian time scale, nowhere near the time needed to develop adaptive responses.^[18]

Patterson focused his attention on lead in food, for which similar experimental deficiencies also had marked increases. In one study, he showed an increase in lead levels from 0.3 to 1400 ng/g in certain canned fish compared with fresh, while the official laboratory had reported an increase of 400 ng/g to 700 ng/g.

In 1978, he was appointed to a National Research Council panel that acknowledged many of the increases and the need for reductions, but other members argued the need for more research before recommending action.[21] His opinions were expressed in a 78-page minority report, which argued that control measures should start immediately, including gasoline, food containers, paint, glazes, and water distribution systems.^[22]

Death

Patterson died in his home in

• J. Lawrence Smith Medal, 1973 (National Academy of Sciences)^[23]
• V. M. Goldschmidt Award, 1980 (Geochemical Society)^[24]
• Tyler Prize for Environmental Achievement, 1995 (University of Southern California)^[25]
• Minor planet
  2511 Patterson is named in his honor.^[26]

• Clair C. Patterson Award,[27] awarded annually since 1998 by the Geochemical Society

Legacy

Patterson was referenced in a 2022 documentary by Derek Muller, The Man Who Accidentally Killed The Most People In History.^[28] Patterson was also featured in "The Clean Room" is the seventh episode of the American documentary television series Cosmos: A Spacetime Odyssey.

References