ATSDR Draft Toxicological Profile for Radon_September 2008.pdf

RADON 873. HEALTH EFFECTSintermediate exposure by any route. No information on the health effects of radon and its progeny inanimals following acute, intermediate, or chronic oral or dermal exposure was located. The onlyinformation available from animal studies was by the inhalation route of exposure, which provides dataon systemic and genetic effects, as well as cancer.3.12.2 Identification of Data NeedsAcute-Duration Exposure. No data were located regarding adverse health effects in humansfollowing acute exposure to radon and its progeny by any route. Single dose studies are available forlaboratory animals that have been exposed by the inhalation and parenteral routes. No information isavailable on acute oral exposure in laboratory animals. Information is available on lethality followingacute inhalation exposure to high doses. However, this study did not provide information on targetorgans, sensitive tissues, or cause of death. No information is available on effects in humans or animalsfollowing relatively low-level acute exposure to radon and its progeny. However, the greatest healthconcern for radon and its progeny is lung cancer, which results from long-term exposure, not acutedurationexposure. Studies designed to assess the potential for adverse health effects in humans followingacute-duration exposure to radon and its progeny do not appear necessary at this time.Intermediate-Duration Exposure. No data were located regarding adverse health effects associatedwith intermediate-duration exposure of humans to radon and its progeny by any exposure route.Epidemiological miner-based studies, in general, have focused on cohorts exposed to radon and itsprogeny for durations >1 year. Animal studies demonstrate that intermediate exposure to high levels ofradon and its progeny can cause chronic respiratory toxicity and lung cancers and indicate that similareffects might occur following intermediate-duration exposure in humans. The relationship between thenature and severity of the respiratory toxicity and the amount of radon exposure is not clearly defined; noris there any information regarding systemic toxicity following intermediate-duration exposure.Additional research on the dose-duration-response relationship between radon exposure and the type andpermanence of resulting toxicity would provide pertinent information. If populations exposed to radonand its progeny for intermediate durations can be identified, such populations could be assessed forpotential adverse health outcomes.Chronic-Duration Exposure and Cancer. Knowledge of the adverse health effects inoccupationally-exposed humans following chronic-duration exposure to radon and its progeny ishistorically based on studies in adult male underground miners. These studies describe predominantly***DRAFT FOR PUBLIC COMMENT***