Consistency of Usage

A particular set of values for tissue doses does not lead to the same numerical value for He and E. For example, assume a case in which the body is partially irradiated, the exposure is primarily to the chest, and the tissue doses are breast, 2 mSv lungs, 1 mSv active bone marrow, 0.2 mSv skin, 0.2 mSv other specific tissues and remainder tissues, negligible. The resulting values are He = 0.44 mSv and E = 0.25 mSv. For this reason, one cannot directly compare previous numerical values of He to current numerical values of E. Note also that a personal monitor located on the front at the chest would have indicated a dose equivalent in excess of 2 mSv, which is an overestimate of either or E. 

As a second example, consider a case in which the front of the body is irradiated by a nonuniform field of scattered radiation, the trunk is shielded by a protective apron on the front of the body, and the personal monitor value and tissue doses are as given in Table 1.3. The resulting values for He and E are 0.12 mSv and 0.05 mSv, respectively. In this case, the difference is caused primarily by the manner in which the remainder contribution is calculated (see Tables 1.1 and 1.2). Note also that a personal monitor located on the front at the neck outside and above the protective apron would have indicated a value of 1 mSv (see Table 1.3), which is a large overestimate of either He or . 

Personal monitor 1.00 (unshielded, outside and above the apron at the neck) 

a dose limit expressed in the quantity He does not carry the same implications for radiation protection as a numerically equal dose limit expressed in the quantity E. For example, a value of He = 10 mSv and a value of = 10 mSv do not carry the same implications for radiation detriment in a working population, as noted in Sections 1.2,2 and 1.2,3. One must be consistent in using He or E only in the context of its corresponding radiation protection system [i.e., He with the ICRP (1977a) or the NRC (1991) systems E with the ICRP (1991) or the NCRP (1993) systems]. 

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Use Consistent Terminology and Concepts. Consistency of usage is needed within and between projects (see above on varied definitions of reference populations, for example). This is a recommendation that can be implemented quickly and relatively easily. Ultimately, this should become part of a larger effort to train various constituencies on what biomonitoring can and cannot tell one about environmental chemicals in humans. Both efforts are vital if there is to be any hope of establishing a minimum of shared knowledge among constituencies so that communicators eventually will not need to recapitulate the entire spectrum of education for each new project. 

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