who underwent greater exposure to ionizing radiation." Effects of sunlight exposure In an Australian study which analyzed the association between solar UV exposure and DNA damage, the results indicated that although the frequency of cells with chromosome breakage increased with increasing sun exposure, the misrepair of DNA strand breaks decreased as sun exposure was heightened. Effects of cobalt-60 exposure The health of the inhabitants of radioactive apartment buildings in Taiwan has received prominent attention. In 1982, more than 20,000 tons of steel was accidentally contaminated with cobalt-60, and much of this radioactive steel was used to build apartments and exposed thousands of Taiwanese to gamma radiation levels of up to >1000 times background (average 47.7 mSv, maximum 2360 mSv excess cumulative dose). The radioactive contamination was discovered in 1992. A seriously flawed 2004 study compared the building's younger residents with the much older general population of Taiwan, and determined that the younger residents were less likely to have been diagnosed with cancer than older people; this was touted as evidence of a radiation hormesis effect. (Older people have much higher cancer rates even in the absence of excess radiation exposure.) In the years shortly after exposure, the total number cancer cases have been reported to be either lower than the society-wide average or slightly elevated. Leukaemia and thyroid cancer were substantially elevated. When a lower rate of "all cancers" was found, it was thought to be due to the exposed residents having a higher socioeconomic status, and thus overall healthier lifestyle. Additionally, Hwang, et al. cautioned in 2006 that leukaemia was the first cancer type found to be elevated amongst the survivors of the Hiroshima and Nagasaki bombings, so it could be decades before any increase in more common cancer types is seen. Besides the excess risks of leukaemia and thyroid cancer, a later publication notes various DNA anomalies and other health effects among the exposed population: There have been several reports concerning the radiation effects on the exposed population, including cytogenetic analysis that showed increased micronucleus frequencies in peripheral lymphocytes in the exposed population, increases in acentromeric and single or multiple centromeric cytogenetic damages, and higher frequencies of chromosomal translocations, rings and dicentrics. Other analyses have shown persistent depression of peripheral leucocytes and neutrophils, increased eosinophils, altered distributions of lymphocyte subpopulations, increased frequencies of lens opacities, delays in physical development among exposed children, increased risk of thyroid abnormalities, and