– Cobalt-60 (possibly from a radiotherapy source) became recycled into steel rebar and used in the construction of buildings in northern Taiwan, principally in Taipei, from 1982 through 1984. Over 200 residential and other buildings were found to have been built using the material. About 7000 people are believed to have been exposed to long-term low-level irradiation as a result. In the summer of 1992, a utility worker for the Taiwanese state-run electric utility Taipower brought a Geiger counter to his apartment to learn more about the device, and discovered that his apartment was contaminated. Despite awareness of the problem, owners of some of the buildings suspected to be contaminated have continued to rent apartments out to tenants (in part because selling the units is illegal). Some research has found that the radiation has had an apparent "beneficial" effect upon the health of the tenants based on the death rate from cancers. Another study looking at the incidence of cancer found that although the overall risk of cancer was sharply reduced (SIR = 0.6, 95% CI 0.5 – 0.7), the incidence of certain leukemias in men (n = 6, SIR = 3.4, 95% CI 1.2 – 7.4) and thyroid cancer in women (n = 6, SIR = 2.6, 95% CI 1.0 – 5.7) was greater. December 6, 1983 – Ciudad Juárez, Mexico. In the Ciudad Juárez cobalt-60 contamination incident, a local resident salvaged materials from a discarded radiation therapy machine containing 6,010 pellets of 60Co. The transport of the material led to severe contamination of his truck. When the truck was scrapped, it in turn contaminated another five tonnes of steel to an estimated of activity. This steel was used to manufacture kitchen and restaurant table legs and rebar, some of which was shipped to the U.S. and Canada. The incident was discovered months later when a truck delivering contaminated building materials to the Los Alamos National Laboratory drove through a radiation monitoring station. Contamination was later measured on roads used to transport the original damaged radiation source. Some pellets were actually found embedded in the roadway. In the state of Sinaloa, 109 houses were condemned due to use of contaminated building material. This incident prompted the Nuclear Regulatory Commission and Customs Service to install radiation detection equipment at all major border crossings. 1984 Lost source accident in Morocco, a Ir-192 source was taken home by a labouer resulting in