1921 - September 15, 1945: Age 24
Harry Daghlian was a physicist working on the Manhatten Project at Los Alamos laboratory in New Mexico. On the evening of August 21, 1945, he was slowing adding tungsten to an apparatus containing a sphere of plutonium, using the audible clicks of a monitor to avoid adding them too quickly. When at one point he heard the clicks speed up, he pulled back his hand, but lost his grip on the brick, which fell into the center of the apparatus. Instinctively he knocked the brick away, avoiding a meltdown, but his hand was inside the blue glow of the plutonium and began to tingle. He dismantled the apparatus to something more stable and was driven to hospital.
Daghlian immediately experienced swelling and numbness, and within 90 minutes acute nausea set in. He vomited almost continually for a day, but after a couple of days of nausea and hiccups his appetite returned. Within 3 days blisters started to apear on his hands. Over the next two weeks these spread all over his body, inside and out. He died just over three weeks after the accident, in great pain.
A security guard who was in the same room about 12 feet away during the accident had no acute symptoms of radiation sickness, but his blood pressure went up and he felt a bit tired for a couple of days. He lived on in apparent good health, even having two children, however he died of leukemia at the age of 62, probably a long-term result of his exposure 33 years before.
Although the accident took place six days after Japan’s surrender, the activities at Los Alamos were still a deep secret, so it was reported he had died of “chemical burns”.
Sources, America’s First Peacetime Atom Bomb Fatality, Wikipedia.