Radiation Dose Implications of Airborne Contaminant Deposition to Humans

Abstract

In nuclear accident consequence assessment, dose contributions from radionuclide deposition on the human body have in the past generally been either ignored or estimated on the basis of rather simple models. Recent experimental work has improved the state of knowledge of relevant processes and parameter ranges. The results presented in this paper represent a first approach to a detailed assessment of doses from radiopollutant deposition on the human body, based on contaminant-specific data. Both the dose to skin from beta-emitters and the whole-body dose from gamma-emitters on body surfaces were found to give potentially significant contributions to dose. Further, skin penetration of some contaminants could lead to significant internal doses.

Skin as a route of exposure and sensitization in chronic beryllium disease.

“…Other researchers tested particle penetration of the skin using particles with diameters of ≥ 3-8 µm (Andersson et al 2002;Lademann et al 1999Lademann et al , 2001). These studies identified clusters of particles on the surface of the skin, at the hair follicle orifice, or within the follicle, but no documentation of particles in the epidermis.…”

Deposition of contaminant aerosol on human skin

“…Therefore, the health consequences of skin deposition of contaminants can be substantial (Andersson et al, 2002). The standard deviations on the figures, which were obtained over a number of experiments with varying conditions, are generally large: of about the same order of magnitude as the mean values.…”

“…Consequently, published data were at that point far too sparse to allow reliable nuclear emergency consequence modelling. By 1998, the severity of this problem had been recognised by, for instance, the developers of the European standard model COSYMA (Jones et al, 1998), and an experimental project had been initiated to investigate the mechanisms governing both beta and gamma doses from deposition of contaminant aerosol on the human body (Fogh et al, 1999;Fogh and Andersson, 2000;Andersson et al, 2002).…”

“…A number of different types of events may lead to considerable radioactive contamination of the human body and a crucial factor governing the fate and impact of the contaminant aerosol is its size (Andersson et al, 2002). For instance, the Chernobyl accident demonstrated that large reactor accidents can cause releases of a range of radioactive aerosols, which can deposit on human populations.…”

“…The contamination in the Thule case was found to be in the form of oxide particles with a log-normal size distribution with a median value of about 2 mm (Eriksson, 2002). A small number of hot particles were found to be much larger (of the order of 20 mm or more), but the clearance half-life of such particles from skin or clothing would be extremely short, so that the doses associated with the deposition of these particles on skin would be expected to be of comparatively minor importance (Andersson et al, 2002). Accidents of this type, which can spread radioactive matter over a considerable area of land (including its inhabitants) have strong parallels to the terrorist radioactive dispersal devices commonly termed 'dirty bombs' (Bunn and Braun, 2003).…”