ML20154P324

Forwards Comments on Hot Particle Rept Per Discussion W/ Gesell,Meinhold & NRC Staff

ML20154P324
Person / Time
Issue date:	09/21/1988
From:	Roecklein A NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
To:	Ney W NATIONAL COUNCIL ON RADIATION PROTECTION & MEASUREMEN
References
NUDOCS 8810030026
Download: ML20154P324 (5)

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SEP t 1 1988 W. Roger Ney Executive Director National Council on Radiation Protection and Measurements 7910 Woodmont Ave.

Suite 800 Bethesda, HD 20814-3095

Dear Dr. Ney:

I You are probably aware that Tom Gesell and Charles Meinhold of SC 80-1 have provided clarifying information on the "hot particle" report in discussions with members of the NRC staff in recent weeks.

Based on your June 17, 1988 letter forwarding the report, it is our understanding that although the report recommendations are final, the report text is still subject to revisiot1.

Following our discussions with Messrs. Gesell and Meinhold, we have developed i

comments on the report which we are enclosing.

We hope these comments will be useful in making any changes to the report that you feel may be justified.

Sincerely,

--- 4d = '

Alan.. Roecklein, Acting Chief v

Radiation Protection and Health Effects Branch Division of Regulatory Applications Office of Nuclear Regulatory Research

Enclosure:

Comments on Hot Particle Report cc:

W. H. Beckner, NCRP T. F. Gesell, NCRP SC 80-1 C. B. Heinhold, NCRP SC 80-1 i

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ENCLOSURE 4

General Suggestions for Improvement NCRP Hot Particle Report Reliance on one set of unpublished data for determining threshold for ulceration:

Explain why only the Forbes-Mikhail data (unpublished) were used to determine the emission threshold. Why were published Englis'n data, which indicate a lower threshold, not included?

I Safety Factor / Conservatism:

Discuss the reason (s) for providing no safety factor an'd discuss the extent to which there is, or is not, conservatism in the recommended limit.

Uncertainties in the recommended limit:

Provide an estimate and discuss.

1 Basis for _using emission rather than dose:

Strengthen argument for use of emlssion.

Late ulceration:

Provide information to support statement regarding absence of lats ulceration from hot particles.

I Other late effects:

Recognize that some late effects (i.e., effect.s appearing more than two weeks after exposure), which are considered to be of no consequence, may appear even at doses below the threshold for 4

ulceration (e.g., dermal thinning).

Discuss any observations of Forbes i

and Mikhail regarding late effects.

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The "simple model" (pp. 19-24):

Clarify this discussion and the relation-l ship of the model to the recommendations.

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Specific Suggestions for Improvements NCRP Hot Particle Report

p. 1, 3rd paragraph, last sentence:

Whether inhalation or ingestion of hot particles constitute a real problem may still be questionable, but the intake of a particle has been experienced by at least one worker.

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). 2, 2nd paragraph, 1st sentence:

Not all hot iowever, it appears that the recommendations (p. particles are insoluble.

27) would not be applicable to a particle going into solution or being absorbed into the skin.

Perhaps this l

should be clearly. stated with respect to the recommendations.

5, 6 3.1, 1st sentence:

g.,t appear to include the t atement that "the most likely ef fect, if enyThe no occurs, is acute skin ulceration."

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p. 5, 6 3.1, 2nd paragra)h, 1st sentence:

What is the basis for the statement that for* hot particles tiese effects "are confined to an area of a few square millimete.rs."

Note that Fig. 3 shows that ulcers (a more serious effect) as large as 8 mm diam.

(50 mm2) were seen by Forbes and Mikhail to result from l

hot particle irradiation.

Also, the plot of Forbes-Mikhail data in a paper by Charles and Wells (1980) shows lesion diameters as large as 14 mm (154 mm2) for

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"depigmentation and dry desquacation."

p. 6,1st paragraph, 3rd sentence:

The basis for the statement concerning l

radiation exposure of a sufficiently small area is not clear.

Further, how is l

l the "dose to a small area" defined given that there is no sharp demarcation of the irradiated area?

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p. 6,1st paragraph, penultimate sentence:

It would be very helpful to provide i

tM basis for this statement concerning late ulceration.

Can any reference (s) be provided? (See alto comment for p.1FTst paragraph regarding "reulceration").

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p. 9, reason that "skin ulceration is taken as being the biological end)oint of concern":

Al't'Eough we believe we understand the NCRP's reason for tiis choice, the reason for it is not clear in the report.

Given the stated risks of fatal and non-fatal cancer at the threshold for ulceration, why is ulcera-1 l

tion taken as being the endpoint?

p. 10, selection of emission limit approach:

The reasons for selecting the emission limit rather than tha dose limit do not appeer to be very strong.

Can j

other (better) reasons be given? (See next comment, also).

l pp. 10-13: What exactly is the "disagreement among various dosimetric meth-ods..." that "...were noted".

Published results for doses calculated using different methods and averaged over 1 cm2 appear to be in relatively good agreement.

Also, the plot (Fig.1) of the Forbes-Mikhail data in terms of "Krebs dose" in a paper by Charles and Wells (1980) shows results very similar to the results in Fig. 3 of the NCRP report.

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pp. 10-13:

Factors of three variatinn with energy and with depth are not cunsidered to be "large differences" in the NCRP report.

Is it correct to infer from this that an uncertainty of a factor of three in the emission limit would not be considered "large"?

p.14,1st paragraph:

The referenced Forbes-Mikhail document is simply an abstract.

Can a more appropriate reference be given to the document (s) and data used by the NCRP? The referenced abstract includes "reulceration" among the dose-dependent responses.

Is this "late ulceration"? The referenced abstract gives doses "at a point 4 mm lateral to the particle and 100 p deep";

however, the penultimate sentence in the first paragraph on p. 14 of the NCRP report says that "These data were originally reported as a function of dose at a depth of 100 pm directly below the particle."

3p. 14-15, determination of threshold dose from Forbes-Mikhail:

It would be 1elpful if the NCRP would provide an estimate of the uncertainty in the thresh-old value selected, considering that all forbes-Mikhail data are above the threshold.

Considerations of English (Hopewell, Charles, et al.) data suggest that the NCRP Forbes-Mikhail value may be high by a factor of 2 to 5.

Does the t

NCRP agree?

The NCRP considers that "the effect near or even somewhat in excess of the threshold are small " What is an ulcer diameter that the NCRP would not consider to be "small" or, in dif ferent terms, what ulcer size, if any, should be prevented?

In other words, it would be helpful if the NCRP more clearly stated its judgement as to what non-stochastic effect(s) from a hot particle on skin should be prevented entir21y.

it appears that late ulceration is at least one of these.

p. 16, 1st complete paragraph:

Whit is the basis for the parenthetical state-ment; can a reference be provided?

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p. 19, lit complete paragraph and p. 20 Fig. 5:

The difference of a factor of about 5 in the two'~0ata points at 071 mm appears to merit some discussion particularly because one of these points is from the paper by Hopewell et al.

that provides most of the data points for this figure, pp. 19-24 development and discussion of the "simple model":

This section is very BT7T,icult to follow; locks claFily.

For example:

The "dose versus distance curve at 100 pm depth" should be provided.

Does the 1.8 mm radius apply at all depths?

It should be made cle ar that this "simple model" does not form ti.e basis for the recommendaticals, if this is the case,

p. 27, recommendation 3, 1st sentence:

The basis for this "cpproximately two weeks" followup does not appear to be clearly and explicitly given in the report.

p 27, footnote 5:

It would be helptui to discuss the reason (s) for deciding not to apply a safety factor.

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p. 27. footnote 5:

Assuming that there are significant conservatisms included l

in the development of the NCRP recommendations, it would seen appropriate to include an explanation of these in the text along with the incorporation of this footnote into the body of the report.

(See also the second and third i

j items under "General Suggestions... ").

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Appendix:

It would be helpful to provide an appendix that (1) summarizes Forbes-Mikhail data, (2) summarizes the manner in which Forbes-Mikhail obtained j

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doses in their experiments, and (3) explains how NCRP obtained emission values from Forbes-Mikhail data.

The information of items (1) and (2) might be provided by appending the manuscript "Acute Lesions in Skin Produced by Radio-active Microspheres.

I. 235 Uranium-Carbide Microspheres," By Forbes and Mikhail.

Reference Charles, M. W. and J. Wells, (1980), "The Development of Criteria for Limiting

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the Non-Stochastic Effects of Non-Uniform Skin Exposure," Proc. 5th Int. Cong.

IRPA, Jerusalem, Vol. 1, pp. 39-42.

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