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# Squamous Cell Carcinoma in the Jaws of Beagles Exposed to 90 Sr Throughout Life: Beta Flux Measurements at the Mandible and Tooth Surfaces and a Hypothesis for Tumorigenesis

N. J. Parks, S. A. Book and R. R. Pool
Vol. 100, No. 1 (Oct., 1984), pp. 139-156
DOI: 10.2307/3576529
Stable URL: http://www.jstor.org/stable/3576529
Page Count: 18
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## Abstract

We present the first detailed dose-response measurements for ${}^{90}{\rm Sr}\text{-induced}$ soft tissue tumors other than hemopoietic dyscrasias in chronically exposed beagles. Twenty-four of 387 dogs exposed to 90 Sr beginning in utero and by continuous ingestion to 540 days of age developed squamous cell carcinoma of the jaw during their lifetime. Eleven of the 24 tumors were observed in dogs ingesting 12 μCi/day and receiving cumulative average skeletal doses of 6500-12,000 rad. None of these tumors was observed in dogs ingesting less than 1.25 μCi/day and receiving cumulative skeletal average doses of 2100-3900 rad, but four were observed at this level. The teeth of these animals acquired a 90 Sr burden that is not removed by skeletal remodeling. Measurements of the radiation dose to soft tissue adjacent to the mandible and teeth of dogs chronically fed 90 Sr indicated the first 10 μm of soft tissue adjacent to teeth received a radiation dose initially about the same as the average skeletal doses. By 2000-3000 days, these tissues received about two to three times that calculated for the average skeletal dose, or about four to six times the mean marrow dose. We suggest that these tumors arise from epithelial rests, which are embryonic tissue trapped in the periodontal membrane between teeth and bone.

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