Patterson, Clair Cameron (1922-1995), an American geochemist , is known for making the first accurate measurement of Earth’s age. Geochemistry is a branch of science that uses chemistry to study Earth’s history and the materials that make up the planet. Patterson later became one of the first scientists to investigate and publicize the dangers of lead pollution in the environment.
Patterson announced his calculations on the age of Earth in 1953. Most scientists at the time thought that Earth and the solar system formed about 3 billion years ago. The solar system includes the sun and all the planets and other bodies that revolve around it. Patterson usedradiometric techniques to determine the age of meteorites, which formed at the same time. Radiometric methods are based on the fact that certain radioactive isotopes (forms of chemical elements) decay at a known rate, breaking down to form different isotopes. By measuring the amount of various isotopes in a sample of rock, scientists can therefore determine how long the decay has been going on and thus how long ago the rock formed. Patterson calculated the age of meteorites by measuring isotopes of uranium and thorium . These isotopes decay into the element lead at a known rate. Patterson calculated that Earth formed about 4.6 billion years ago. Later research by other scientists supports this figure.
In later research, Patterson studied lead in the air and soil and determined that levels were hundreds of times higher than in prehistoric times. He recognized that high levels of lead in the environment, resulting mainly from the use of leaded gasoline , represented a serious threat to human health (see Lead poisoning ). Tetraethyl lead was once commonly added to gasoline to improve engine performance. Engines that burned tetraethyl lead released in their exhaust poisonous lead that could be inhaled by people or deposited in soil and water. Health problems develop as lead levels in the body increase. Lead is especially damaging to the developing nervous system and brain cells of children.
Patterson’s research was instrumental in the effort to pass the Clean Air Act of 1970. The United States government also banned lead-based paint for household use, restricted lead in other products, and began regulating the use of lead in industry. The law ended the production of leaded gasoline and set air quality standards that limit the amount of lead that can be released into the air by industry.
Clair (also spelled Claire) Cameron Patterson was born on Jun. 2, 1922, in Mitchellville, Iowa, near Des Moines. He studied chemistry at Grinnell College in Iowa, graduating in 1943. He received his Ph.D. degree in chemistry from the University of Chicago in 1951. He took a position as a researcher at the California Institute of Technology (often called Caltech) in 1952, later becoming a professor there. He spent his entire career at Caltech, retiring in 1992. He died on Dec. 5, 1995.
