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MEMO

TO: Procedures Review Subcommittee 

FROM: John Mauro, SC&A

DATE: January 7, 2014

SUBJECT: SC&A Position Regarding Skin Exposures Associated with the Direct Deposition 

of Fine Particles and Flakes of Uranium Oxide onto Skin and Clothing

A skin exposure scenario that has been a concern of SC&A for many site profiles and dose 

reconstruction reviews, and discussed at numerous work group and Subcommittee meetings, is 

the direct deposition of fine particles of dust and large flakes of airborne uranium oxide on bare 

skin and clothing. Many AWE facilities, especially those that machine, roll, extrude, grind, or 

otherwise handle uranium, are known to generate large quantities of airborne uranium dust.

Many DOE facilities, such as Fernald and Hanford, have also machined uranium and generated 

large quantities of dust. A description of the types of activities that have generated large 

quantities of dust is provided in TBD-6000 (Battelle 2011).

SC&A has reviewed many site profiles, dose reconstructions, and NIOSH procedures where a 

full range of exposure scenarios are evaluated in depth. However, we have found that exposures 

associated with the direct deposition of uranium oxide dust and/or flakes onto skin and clothing 

have not been addressed. This SC&A issue was discussed to some extent at the May 21, 2013,

meeting of the Dose Reconstruction (DR) Subcommittee; the Subcommittee recommended that 

the subject be transferred to the Procedures Review Subcommittee as a generic issue.

Subsequent to the May 21st DR Subcommittee meeting, and at the request of SC&A, our Project 

Officer authorized SC&A to prepare a report presenting SC&A’s understanding and position 

regarding this matter. SC&A presents its position in a report titled, “Discussion Points 

Regarding Reconstructing Localized Skin Dose Associated with Direct Deposition of Uranium

Oxide and Flakes on Skin” (SC&A 2013). This report was subsequently discussed at the July 

18, 2013, meeting of the Procedures Review Subcommittee. This memo presents SC&A’s 

understanding of the current status of the issues identified in SC&A 2013 and discussed at the 

July 18th meeting of the Procedures Review Subcommittee. SC&A’s recommendations and our 

understanding of action items that emerged from the July 18th meeting are in bold in this memo.

The issues addressed in our report and the two Subcommittee meetings can be conveniently 

discussed from two perspectives. The first is the chronic direct deposition of fine dust particles 

directly onto skin and clothing, and the second is the deposition of large visible flakes directly 

onto skin and clothing.

Fine Particles

SC&A (2013) presents our concerns regarding exposure to fine particles. As indicated in that 

report, we agreed with the basic approach adopted by NIOSH, but recommended that NIOSH 

consider exposure to bare skin and also to skin beneath clothing, and we suggested a method for 

addressing “attenuated” beta exposures due to the presence of clothing. Our position on this 
Memo to the Procedures Review Subcommittee 2 SC&A – January 7, 2014

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

matter remains unchanged. SC&A believes that NIOSH concurs with this position, but 

recommends that this issue remain in abeyance until NIOSH makes appropriate revisions 

to its procedures related to skin exposures.

SC&A questions NIOSH’s position regarding the limited exposure duration (i.e., 8 hours per 

working day in a potentially dusty environment) on the premise that (1) the worker showers 

immediately at the end of each workday along with a change out of clean clothing, and 

(2) contaminated work clothing is successfully washed/decontaminated prior to reuse. This issue 

was discussed at the July 18th meeting of the Procedures Review Subcommittee, and it was 

acknowledged that acceptable protocols for workers in such environments have been to 

(1) require protective clothing (i.e., anti-Cs), (2) monitor for contamination, and (3) when 

contamination is detected, subject the individual to a formal/supervised decontamination 

protocol. As cautioned during the July 18th meeting, even under these protocols, a successful, 

complete decontamination is frequently not achievable. In addition, during the early years of 

AWE activities, such protocols may not have been in place, and if they were, they were not 

always followed. In all likelihood, during the early days of AWE operations, uranium dust was 

probably considered more of a nuisance than a potential source of radiation exposure. As such, 

after working with uranium, worker cleanup processes and activities may not have differed 

substantially from those performed after working with non-radiological materials, such as steel. 

In light of these discussions, SC&A believes that this issue would benefit from additional inquiry 

regarding earlier work practices, personnel contamination controls, and the ability to remove 

uranium contamination from skin and clothing.

 

This issue was explored to some degree during the July 18th meeting, in that NIOSH 

representatives with actual experience at uranium facilities, such as Fernald, found that uranium 

was not difficult to remove from skin and clothing. In addition, NIOSH representatives pointed 

out that the types of radionuclides and the conditions of exposures where it was difficult to 

remove contamination, such as the exposures that were experienced by the Marshall Islanders, 

were quite different than the exposures experienced at uranium facilities. SC&A recommends 

that NIOSH provide some documentation of this experience with respect to uranium 

decontamination of skin and clothing so that this issue can be closed.

During our discussion at the July 18th meeting, NIOSH pointed out that NIOSH has, in fact,

accounted for skin exposures associated with contaminated clothing by referring to the methods 

used to reconstruct doses at the Bethlehem Steel facility. NIOSH pointed out that there was 

documentation that workers’ clothing at Bethlehem Steel was often contaminated with difficultto-remove uranium contamination, and that the dose reconstructions have taken this exposure 

pathway into consideration. Based on this discussion, it appears that NIOSH is prepared to take 

this exposure scenario into consideration on a case-by-case basis. In light of this, SC&A 

recommends that this issue remain open until NIOSH completes its investigations into this 

matter [as indicated on page 57 of the July 18th transcript (ABRWH 2013b)] and

appropriately revises its procedures to address this issue.

As part of our review of NIOSH’s position, we independently checked the dose conversion 

factor (DCF) employed by NIOSH for deriving dose to skin from the direct deposition of 

uranium dust onto skin (i.e., 40 mrem per 10,000 dpm/cm2per hour) and concur with this value.
Memo to the Procedures Review Subcommittee 3 SC&A – January 7, 2014

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

Section 6 of SC&A 2013 also raises questions regarding partial exposures of the body from 

direct deposition and the statistical distribution of the dose over the entire body, as described in 

ORAUT-OTIB-0017 (ORAUT 2005). We agree with this approach as long as the input to IREP 

is an estimate of the exposure to the skin of the entire body, taking into consideration exposure to 

bare skin and also skin covered by clothing. Our original concern regarding partial body 

exposure was that we believed, since the risk coefficients imbedded in IREP are for uniform 

exposure of the skin of the entire body, and the baseline risk of skin cancer is for the entire body, 

that the input doses for skin exposure should also be an expression of the whole exposure of the 

skin of the entire body. We now understand that this is, in fact, the approach that NIOSH plans 

to use, including doses beneath clothing. Given this understanding, our concerns with respect to 

this matter have been resolved. However, we recommend holding this issue in abeyance until 

NIOSH issues a revision to its procedures confirming our understanding of the protocols 

NIOSH plans to use, especially with respect to skin exposures beneath clothing.

Before leaving this subject, it should be pointed out that there was an interesting discussion of 

partial skin exposures beginning on page 56 and extending to page 76 of the July 18, 2013,

meeting transcript (ABRWH 2013b). It was generally agreed that this whole matter of partial 

skin exposure and the IREP baseline risk deserves a little more attention and may, in fact, be 

beyond our current knowledge regarding risks associated with partial body skin exposures. 

SC&A recommends that this subject be addressed as an overarching issue, but should not 

hold up dose reconstructions, since OTIB-0017 (ORAUT 2005) currently provides for 

partial skin exposures.

 

Large Uranium Oxide Flakes

It has been SC&A’s position that machining of uranium metal can produce flakes/particles (in 

the range of 1 to several mm in diameter) of uranium oxide that may deposit unnoticed onto skin 

and clothing. This position emerged as a result of our review of many site profiles, beginning 

with our review of the Bethlehem Steel site profile. Based on extensive previous work, we 

believe that NIOSH would agree that the dose rate to the skin beneath such flakes depends on the 

size of the flakes, but can be as high as 240 mrem/hr.

Discussion during the May 21, 2013, meeting (ABRWH 2013a) revealed differences of opinion 

among the Board members regarding the plausibility of such exposures. Some Board members 

felt that large/mm-size flakes/particles were not necessarily produced because of the oil used to 

prevent the oxidation and flaking of uranium during machining/grinding, and that workers wore 

protective clothing and were monitored when leaving work areas. Other Board members 

believed that, at least in the early years of AWE operations, experience with uranium machining

was limited and such scenarios were plausible.

The plausibility issue was also discussed at the July 18th meeting and reference was made to the 

residence time of particles on skin as cited in RESRAD documentation. SC&A believes that 

this issue would benefit from additional inquiry into the literature, and recommends that 

NIOSH provide some written documentation on this matter before the issue is closed.
Memo to the Procedures Review Subcommittee 4 SC&A – January 7, 2014

NOTICE: This report has been reviewed for Privacy Act information and has been cleared for distribution.

However, this report is pre-decisional and has not been reviewed by the Advisory Board on Radiation and Worker 

Health for factual accuracy or applicability within the requirements of 42 CFR 82.

It is SC&A’s position that such an exposure scenario should be considered at sites and during 

time periods where controls and protocols involving the machining of uranium metal were 

limited and there is some evidence that the machining operations could generate uranium oxide 

flakes. In light of these discussions, we recommend that the issue of the plausibility of large 

flake exposures remain open until additional investigations by NIOSH demonstrate that 

such scenarios are not, in fact, plausible.

In considering this scenario, one can envision a worker with a skin cancer but no evidence that 

the worker was contaminated with large flakes. Under these conditions, SC&A recommends 

using the protocols described in ORAUT-OTIB-0017 (ORAUT 2005), where the skin exposure 

under a hypothetical flake is averaged over the entire surface area of the body. If, however, the 

records show surface contamination of the worker is reported as an off-normal event, then the 

dose to the skin used as input to IREP should not be averaged over the entire surface area of the 

body; the input to IREP should be based on the exposure rate to the skin under the flake (which 

could be as high as 240 mrem/hr) and an 8-hour time period of exposure for each incident 

identified in the worker’s records. We believe that this strategy in dealing with exposure to large 

flakes of uranium oxide is consistent with the approach that NIOSH plans to use when such 

exposure scenarios arise for individual cases. If NIOSH concurs with this basic strategy for 

addressing skin exposures to particles/flakes of uranium, we recommend that this issue be 

closed or placed in abeyance.

REFERENCES:

ABRWH 2013a. Transcript of the Advisory Board on Radiation and Worker Health, 

Subcommittee on Dose Reconstruction, Tuesday, May, 21, 2013, convened at 9:00 am in 

Hebron, Kentucky. ABRWH, National Institute for Occupational Safety and Health, Cincinnati, 

Ohio. May 21, 2013.

ABRWH 2013b. Transcript of the Advisory Board on Radiation and Worker Health, 

Subcommittee on Procedures Review, Thursday, July 18, 2013, convened at 8:30 am in Idaho 

Falls, Idaho. ABRWH, National Institute for Occupational Safety and Health, Cincinnati, Ohio. 

July 18, 2013.

Battelle 2011. Site Profiles for Atomic Weapons Employers that Worked Uranium Metals. 

Battelle-TBD-6000. Rev. 01. National Institute for Occupational Safety and Health (NIOSH); 

Cincinnati, Ohio; Division of Compensation Analysis and Support (DCAS); effective June 17, 2011; 

SRDB Ref ID: 101251.

ORAUT 2005. Interpretation of Dosimetry Data for Assignment of Shallow Dose, ORAUTOTIB-0017, Rev. 01. Oak Ridge Associated Universities Team, Cincinnati, Ohio. October 11, 

2005.

SC&A 2013. “Discussion Points Regarding Reconstructing Localized Skin Dose Associated 

with Direct Deposition of Uranium Oxide Dust and Flakes on Exposed Skin,” Rev. 0. SC&A, 

Inc., Vienna, Virginia. June 12, 2013.