Physicians for Social Responsibility

Physicians for Social Responsibility (PSR), a nonprofit organization, was founded in 1961 after a group of Boston, Massachusetts, physicians sought to analyze the medical implications of nuclear weaponry, including what they believed were the deleterious effects of the presence of strontium 90 in the environment.

Strontium 90, an isotope, is a by-product of the fission of uranium and plutonium in both nuclear weapons and nuclear reactors that produce nuclear power. Large amounts of strontium 90 were emitted during atmospheric nuclear weapons testing in the 1950s and 1960s, and it is considered one of the most hazardous by-products of nuclear waste. Because strontium 90 is chemically similar to the chemical element calcium, it can concentrate in bones and teeth, and PSR was involved in early studies that ...