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Talk to Terrie: A Guide to Accessing Department of Labor’s Site Exposure Matrix Database

January 7, 2019

January 7, 2019

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My husband, a former worker from the Rocky Flats plant, and I have a model train set.  We recently purchased a rail car which contains Department of Energy and Atomic Energy Commission logos and is used to transport thorium ore.

I bet you are scratching you head wondering how a model train set relates to the Department of Labor’s Site Exposure Matrix (SEM).  While it really doesn’t, I thought it would be a fun way to explain how to access the SEM and explore the information located in the database.

My husband and I decided that the theme for the layout would be nuclear weapons production.  One side would be a uranium mill and the other a small scale production facility.  I searched the internet to see if there were any historical pictures of the mill which was located 30 miles west of me, in Maybell, Co.  I actually found an issue of a local paper detailing the opening of the mill in 1957.

This find led me to see what year the Department of Labor (DOL) determined was the first year the Maybell mill was covered.

I went to SEM.  You can find the link on the left-hand side of DOL’s website,

Claimant Resources

Clicking on the link above highlighted in red will take you to this page,

This page is a bit difficult.  The link to the SEM database is not prominently placed.  I highlighted the link in red.

To ensure that SEM data accurately reflects information regarding the work processes conducted at a covered facility, the DEEOIC is drawing upon a wide range of data sources. Accordingly, DEEOIC has established a SEM website for viewing and comment on the Internet. To access the SEM website, please go to This website also contains information regarding scientifically established links between toxic substances and recognized occupational illnesses. DEEOIC’s goal in launching and maintaining this website is to display its findings and provide a forum for collecting additional information relative to the SEM website.

After clicking on the link, you will arrive at the SEM page.  The right-hand side provides options to submit information to the SEM administrator and a button to enter the database itself.

Upon entering the SEM, you will be asked what type of facility you wish to search.

By selecting “Colorado” in the State drop-down menu on the uranium mill page and then Uranium Mill in Maybell, CO I was brought to this page.

As you can see, there’s a wealth of information in the SEM.  And, yes, SEM shows that the Maybell mill began operations in 1957.  This applies to all sites listed in SEM.  Sites that are designated as Department of Energy sites such as Rocky Flats also contain information on various buildings.  Please note that Atomic Weapons Employees and Beryllium Vendor facilities are not in the SEM.  This is because those sites are not covered under Part E.

The SEM administrator also invites the public to provide any documentation to improve the database.  Just click on the Submit Site-related or Disease-related Information buttons and follow the instructions.

And for those who are curious about the rail car, here it is.