Soluble uranium chemical intake limits - NRC vs OSHA/NIOSH

[Huey0001@AOL.COM]

A question came up by the Industrial Hygiene staff here.  The question is; Why does 10 CFR 20.1201(e) allow workers to receive 10 milligrams of soluble uranium a week when OSHA only allows 2.5 milligrams per week soluble U?



10 CFR 20.1201(e) states “In addition to the annual dose limits, the licensee shall limit the soluble uranium intake by an individual to 10 milligrams in a week in consideration of chemical toxicity (see footnote 3 of appendix B to part 20).” 



Footnote 3 states “For soluble mixtures of U-238, U-234, and U-235 in air, chemical toxicity may be the limiting factor (see § 20.1201(e)). If the percent by weight (enrichment) of U-235 is not greater than 5, the concentration value for a 40-hour workweek is 0.2 milligrams per cubic meter of air average.  For any enrichment, the product of the average concentration and time of exposure during a 40-hour work week shall not exceed 8E-3 (SA) uCi-hr/ml, where SA is the specific activity of the uranium inhaled.  The specific activity for natural uranium is 6.77E-7 curies per gram U.”



It appears that Foot Note 3 in 10 CFR 20 Appendix B is using the insoluble U limit published by OSHA and NIOSH.



OSHA and NIOSH exposure limits for soluble U is 0.05 milligrams per cubic meter and 0.2 milligrams per cubic meter for insoluble U.



Any feed back would be appreciated.



Thanks





Paul Jung, RRPT

Radiation Safety Officer

Sevenson Environmental Services, Inc.

2749 Lockport Rd

Niagara Falls, NY  14305

716-284-0431

716-284-1796 fax

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