Abstract:
Human health risks posed by exposure to elevated levels of 222Rn in caves are not well documented. Various studies throughout the world have detailed the often very high 222Rn gas concentrations in caves and exposures to cavers and commercial tour guides and other employees, but without a consequent assessment of the overall impact on human health. Although 222Rn concentrations in caves are considered high relative to most above ground dwellings, the levels identified are also considered to be low for ionizing a radiation. Low-level ionizing radiation impacts on human health are deduced by application of the linear no-threshold theory (LNT) of radiation carcinogenesis. Comprehensive reviews of the published literature and an understanding of exposure time suggests that commercial cave workers (e.g., tour guides) and commercial 238U-mine workers are both exposed for the same number of hours per month (,170 h), but cave workers are exposed to much lower 222Rn concentrations than are mine workers. Cavers will generally be exposed for a smaller number of hours per month. Risk estimates suggest that cavers will likely be subject to insignificant risks, but that cave workers may be subject to low-level risks of developing lung cancers from elevated levels of 222Rn gas concentrations in caves.