8/18/2005

, , 

As requested at the July 6, 2005 Board meeting in St. Louis, a Working Group of the Board includ

Petitioner Denise Brock, SC&A staff, and NIOSH staff have been diligently working through the 6 

tasks (see attached “Priority Issues for demonstrating feasibility of dose reconstruction for MCW 

workers...”) identified by the Board. 

These tasks, as the title of the attached list indicates, addresses issues regarding how dose 

reconstruction will be accomplished for Mallinckrodt workers and specific radiation exposure 

situations. As a result of the work on these 6 tasks and the discussions held, NIOSH has revised 

presents as attached a DRAFT Mallinckrodt Chemical Company Site Profile (ORAUT-TKBS-0005

for the Board’s deliberations at its next meeting (August 24-26, 2005). To explain in a general sen

how dose reconstruction is to be accomplished for workers who may have been exposed to urani

process residue streams and may not have been fully monitored for that exposure, the attached d

revision of the site profile has been modified at Section 6.0, page 103, with the following language

"For uranium process residues, because the ability is limited to accurately determine the fract

of time a worker spent in any given part of the residue stream areas, the approach to assignin

intakes from uranium progeny will be based on the highest dose delivered by either establishe

source term. That is, NIOSH will separately evaluate the dose from inhalation of either radium 

bearing or thorium bearing residues. Intakes of thorium bearing residues will be estimated fro

air monitoring data using the 95th percentile of the distribution of air measurements observed 

plant 6. Intakes of radium bearing residues will be estimated using the worker’s individual ra

in breath measurements when available or on the 95th percentile of the distribution of breath 

measurements when no samples for the individual have been located. Thus, the dose will be 

reconstructed for each source term and the value that provides the highest probability of 

causation will be used." 

Additionally, attached is the recent SC&A 3rd supplement review report on the MCW site profile w

includes all of the documents created in response to the 6 tasks and which were used in discussio

by the Working Group of the Board. (Each of you have already received these documents separa

as they were developed and compiled in the SC&A Report, they are presented again here in one 

place with the site profile for your convenience. The SC&A report, and the site profile revision, ha

also been placed on the NIOSH website.) Upon conclusion of the Board’s deliberations regarding 

Mallinckrodt Chemical Works, these documents (and any forthcoming recommendation(s) from th

Board) will serve to facilitate and expedite our consideration toward completion of a fully revised 

(modifications especially to Section 6.0, page 103) site profile for immediate dose reconstruction 

Our intent and hope is that the attached general revision of the site profile and accompanying 

documents will serve the Board well in its deliberation regarding the Mallinckrodt Chemical Works 

profile and SEC petition. 

Due to the large volume of the documents, you might have difficulty downloading them so we will 

be placing a hardcopy in the fed-ex to you today. 

Respectfully, 

Larry J. Elliott
 

Director
 

Office of Compensation Analysis and Support
 

National Institute for Occupational Safety and Health