Mastick is known for a lab incident in 1944 when he accidentally ingested a small amount of plutonium, traces of which remained detectable in his body decades later.

[3] Mastick moved to Los Alamos early in 1943, where he worked in the Chemistry Division and studied the mysterious chemical properties of plutonium, a synthetic element then available only in microscopic quantities.

Gases had built up in the vial overnight, most likely through the dissociation of water molecules due to alpha radiation from the plutonium.

[5] Mastick replaced the vial in its wooden container, and went to see Dr. Louis Hempelmann, the director of the Health Group at Los Alamos.

Hempelmann phoned Colonel Stafford L. Warren, the Manhattan Project's medical director, at the Clinton Engineer Works in Oak Ridge, Tennessee.

Hempelmann gave him a mouthwash of trisodium citrate, which would combine with the plutonium to form a soluble liquid, and sodium bicarbonate, which would make it solid again.

[5][6] Unable to work in the Chemistry Division any more because of the accident, Mastick suggested to Oppenheimer that he become an assistant to Commander Frederick Ashworth.

[1] Mastick returned to the University of California, where he earned his PhD in 1950, writing his thesis on A study of gaseous oxides at high temperatures.

Initially located in Saddle River, New Jersey, the business subsequently expanded into seven states, and earned accolades including one presented by Nancy Reagan at the White House in Washington, D.C.[1][9] Mastick died in Santa Barbara, California, on September 8, 2007.