No one escapes a nuclear blast unscathed.

North Korea’s recent weapon tests, along with the exchange of aggressive statements between the US and North Korea, have brought the threat of nuclear war back to present consciousness.

Most experts think that sort of catastrophic conflict is unlikely, but even the possibility should be sobering. Physicist Lawrence Krauss recently wrote that any discussion of nuclear weapons should force leaders to confront the “horrifying realities” involved.

In that vein, it’s worth remembering that such an event isn’t just devastating for the people and areas exposed to the initial blast. Those who survive are still likely to be contaminated by radiation.

From what researchers can tell, even people more than five hundred miles away from massive nuclear tests have encountered enough radiation (due to weather blowing it in their direction) to increase cancer rates and permanently harm babies in utero.

The nuclear explosions that came at the end of World War II — and the explosions from hundreds of nuclear tests in subsequent years — still have demonstrable effects on human health. Every living thing on the planet today shows some sign of being exposed to the radiation emitted in the era of widespread nuclear testing.

What we know about long term effects of radiation exposure

The bomb dropped on Hiroshima on August 6, 1945 killed between 90,000 and 166,000 people, due to the initial force, heat, and direct radiation exposure. Three days later, the bomb at Nagasaki killed another 60,000 to 80,000.

But that wasn’t all — radiation continued to affect the survivors. Those effects have been studied ever since, with most research conducted by a joint Japan-US organization called the Radiation Effects Research Foundation.

Researchers have found that babies who were exposed to radiation from the bombings in utero were significantly more likely to be born with small head size, mental disabilities, and were less likely to grow to normal height. Children born to women who were within 2.5 km of the edge of the fireballs were at least five times as likely to demonstrate these effects when compared to people farther away.

Among survivors, cancer rates in general rose approximately 10%, according to RERF data. Leukemia rates rose more — almost 50% — and had the biggest effect on children. (This primarily affected people who were young at the time of the explosions, so the effect has mostly disappeared in the years since.)

After the war, nuclear testing by major superpowers entered its heyday. The US and Soviet Union both detonated hundreds of nuclear weapons before signing the Partial Test Ban Treaty in 1963, which prohibited above-ground nuclear tests.

Because of those tests, “radioactive particles and gases were spread in the atmosphere,” according to the CDC. That effect was widespread enough to deposit radiation all over the globe. Anyone who has lived in the US after 1951 has received some exposure to fallout. All of our organs and tissues show some sign of it.

In most cases, the potential increased cancer risk from that exposure is very small. (Most of us receive far more radiation regularly from X-rays and similar procedures.) But at least one CDC study estimated that fallout could eventually be responsible for up to 11,000 cancer deaths in the US, according to New York Times coverage of the study. Continue reading.