Identified by the EPA in 1980, the Welsbach/General Gas Mantle site contained soil and building materials contaminated with radioactive materials. Radiation became prominent when the companies used thorium, a radioactive element withdrawn from monazite ore, in the production of their gas mantles. In the late 19th century and early 20th century, Welsbach Company was located in Gloucester City, which borders Camden, and was a major producer of gas mantles until gas lights were replaced by electric lights. The fabric of the Welsbach gas mantle was put into a solution that consisted of 99% thorium nitrate and 1% cerium nitrate in distilled water, causing it to emit a white light. Operating from 1915 to 1940 in Camden, General Gas Mantle, or GGM, was a manufacturer of gas mantles and served as a competitor for Welsbach. Unlike Welsbach, General Gas Mantle used only a refined, commercial thorium solution to produce its gas mantles. Welsbach and General Gas Mantle went out of business in the 1940s and had no successors.