Abstract:
:This work studies the effect of age on lung dose commitments arising from the inhalation of an atmosphere containing radionuclides of varying half-lives and physical sizes. This dependence is significant in many cases, approaching a ratio of 2 in several instances when the maximum dose at a given age is compared with that for an adult. In most instances, the maximum dose occurs between 4 and 8 years of age, due to a combination of small channel radii (allowing greater diffusional deposition), low lung mass, and high breathing rate. Age-dependence is largest for particles in the range 0.01 to 0.1 micrometer, a range coincident with that normally encountered in atmospheric aerosols. Resting activity appears to provide the largest age-dependence, particularly for short-lived radionuclides. The study focused on radionuclides whose half-lives were less than 2 years. Total lung doses for longer lived radionuclides are dominated by pulmonary deposition and may be computed from the data in the figures, given a knowledge of the transit times for the tracheo-bronchial region. From the present results, it appears likely that current maximum permissible levels of exposure to airborne radionuclides may require re-evaluation to ensure that children do not receive unacceptably large dose commitments. Further revision may be required upon the incorporation of age-dependent risk factors.
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Crawford DJdoi
10.1088/0031-9155/27/4/005subject
Has Abstractpub_date
1982-04-01 00:00:00pages
539-52issue
4eissn
0031-9155issn
1361-6560journal_volume
27pub_type
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