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Submitted by Dr.B.S.Rao, Bhabha Atomic Research Centre
   Commenting as an individual
Document 2005 ICRP Recommendation
 
Tissue weighting factor for gonads

It has been suggested that the tissue-weighting factor for gonads be reduced to 0.05. It is indeed justified in the light of the new information and improved understanding of the mechanism of induction of mutations and their transmission. But now, there arises a need to impose a limit on exposures to prevent the occurrence of deterministic effects (temporary sterility in males). When the tissue-weighting factor (WT) is 0.2 the limit for single exposure to gonads alone, works out to be 100 mSv (20 mSv divided by 0.2). This dose is below the threshold (150 mSv) for causing the deterministic effects. But if the WT is reduced to 0.05, the maximum single dose to gonads alone works out to be 400 mSv (20mSv divided by 0.05). This dose can cause temporary sterility and oligospermia among many of the exposed. Hence, the need to recommend a separate equivalent dose limit of 100 mSv to the gonads.