1962: Thalidomide, often prescribed for morning sickness, is suspected of causing birth defects, adding to already widespread concern about the dangers of synthetic chemicals.

Today: The Environmental Protection Agency requires pesticide makers to submit data that will allow the agency to determine the special risks of their products for children.

1962: Watson, Crick, and Wilkins win a Nobel Prize for describing the molecular structure of DNA.

Today: Scientists complete a provisional map of the entire human genome.

1963: President Lyndon Johnson signs the Clean Air Act, legislation designed to protect air quality in the United States.

Today: The United Nations agree to the Kyoto Protocol, a plan for reducing emission of greenhouse gases.