ATSDR Draft Toxicological Profile for Radon_September 2008.pdf

RADON 913. HEALTH EFFECTShigher regions (tracheobronchial area). These studies could identify the appropriate animal model forfurther study of radon-induced adverse effects, although differences in anatomy and physiology of therespiratory system between animals and humans require careful consideration. Most of the informationavailable on the toxicokinetics of radon and progeny has been obtained from studies of inhalationexposure. Studies on the transport of radon and progeny following oral and dermal exposures would beof use for comparing different routes of exposure, although oral and dermal exposure routes do not appearto be of particular toxicity concern.Methods for Reducing Toxic Effects. Lung cancer is generally considered to be the only toxicityconcern following long-term exposure to radon and radon progeny. The high-energy alpha emissionsfrom radon progeny deposited in the lung are the source of toxicity concern. The sequence of eventsleading from irradiation of living cells is generally believed to involve ionization that causes cellulardamage that includes DNA breakage, accurate or inaccurate repair, apoptosis, gene mutations,chromosomal change, and genetic instability. Cigarette smoke appears to interact with radon and itsprogeny to potentiate their effects.Methods for reducing the potential for radon-induced toxic effects consist of monitoring indoor air forradon levels, reducing potentially hazardous levels by ventilation and other accepted radon removalmethods, and cessation of cigarette smoking.There are no known methods for reducing peak absorption or body burden of radon progeny. There issome indication that diets high in fruits and vegetables might be of benefit in neutralizing reactive oxygenspecies produced by cigarette smoke and radon (see Alavanja 2002).Children’s Susceptibility. If data needs, relating to both prenatal and childhood exposures, anddevelopmental effects expressed either prenatally or during childhood, are identified, they are discussedin detail in the Developmental Toxicity subsection above.Differences in lung morphometry and breathing rates in children may result in higher estimated radiationdoses relative to adults (NCRP 1984a; Samet et al. 1989). However, available information from childrenemployed as miners in China does not provide evidence of increased susceptibility to the effects ofexposure to radon (Lubin et al. 1990; NIH 1994).***DRAFT FOR PUBLIC COMMENT***