The Department of Labor (DOL) is responsible for determining the probability that a cancer included in a claim under EEOICPA (The Act)
was caused by workers' exposure to radiation during nuclear weapons production. DOL will determine the "probability of
causation" for each claim for which NIOSH is required to complete a dose reconstruction. Generally, with some exceptions,
these claims are for workers who are not a member of the Special Exposure Cohort.
To answer questions about the probability of causation, NIOSH developed a list of Frequently Asked Questions (FAQs) below.
Links to other program FAQs are located on the "Find It!" navigation box under "On this page . . . "
Select the question you are interested in below by clicking its link. You will be taken to the answer located on this page. Links throughout the FAQs will guide you to further information.
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Probability of Causation
- What is "probability of causation"?
Under EEOICPA (The Act), probability of causation is a measure of how likely it is that an energy employee's cancer was "at
least as likely as not" caused by occupational exposure to ionizing radiation.
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- What does dose reconstruction have to do with the probability of causation?
The Department of Labor (DOL) will use the energy employee's personal characteristics, employment, medical information, and dose reconstruction
results developed by NIOSH to determine the probability of causation.
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- What is the Probability of Causation rule?
This rule provides the guidelines that DOL uses to determine the degree of likelihood that a cancer included in a case
was "at least as likely as not" caused by the energy employee's exposure to radiation during nuclear weapons
production.
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- Where can I find a copy of the Probability of Causation rule?
A copy of the Probability of Causation rule can be found on our Web site on The Act page.
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- How is probability of causation calculated under EEOICPA (The Act)?
NIOSH developed a computer program that is used by DOL to determine the probability of causation. The computer program,
known as NIOSH-IREP, uses cancer risk models developed primarily by the National Cancer Institute (NCI) to estimate the
probability of causation under The Act.
The risk models take into account the energy employee's cancer type, year of birth, year of cancer diagnosis, exposure
information (years of exposure, radiation type, and dose). Smoking history is taken into account for lung cancer cases.
Ethnicity is taken into account for skin cancer cases. Under Subtitle B of The Act, exposures to other occupational,
environmental, or dietary carcinogens are not currently taken into consideration for the probability of causation
calculation.
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- What is the significance of the probability of causation calculation?
Probability of causation is expressed as a percentage between 0 and 100. A value of 100% means that it is certain that the
radiation dose was the cause of the cancer. A value of 0% means that it is certain that the radiation dose was not the cause
of the cancer. As defined in The Act, probability of causation values greater than or equal to 50% at the upper 99th
percentile credibility limit mean that it is "at least as likely as not" that the radiation dose caused the
energy employee's cancer. Therefore, if the probability of causation for your case is less than 50%, you will not be
entitled to compensation. If your probability of causation is between 50% or greater, DOL will recommend that you receive
compensation.
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- Does NIOSH determine/calculate the percent that determines the compensability of the
claim?
No. NIOSH reconstructs a worker's radiation dose and determines a final estimate of the worker's exposure to radiation.
The results from a worker's dose reconstruction are sent to DOL. DOL determines the probability of causation - the
likelihood that the worker's cancer was related to radiation exposure received while employed at a covered facility.
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- NIOSH completed my dose reconstruction and DOL calculated the probability
of causation for my claim to be less than 50%. As a result, DOL's recommended decision was to deny compensation
for my claim. I have subsequently had two additional cancers. I reported the two additional cancers to DOL and
my case was returned to NIOSH for a new dose reconstruction. NIOSH completed the new dose reconstruction using
my two additional cancers and when DOL determined my probability of causation, it was again less than 50%. In
fact, once the two new cancers were added to my dose reconstruction, the probability of causation percentage
calculated by DOL was lower than the value of my first dose reconstruction. How is this possible? Shouldn't the
addition of two more cancers increase the probability of causation value?
NIOSH understands this concern. It may seem obvious that when additional cancers are added to a dose reconstruction
it would increase the probability that radiation caused the multiple cancers. However, in some cases, the NIOSH
dose reconstruction will result in a lower probability of causation when additional cancers are added. An
explanation for how and why this can happen is as follows:
Accurately estimating the exposure a worker received while working at a covered facility is a time consuming process.
In order to complete dose reconstructions in as timely and efficient a manner as possible, NIOSH may make
assumptions on dose estimates that are favorable to the claimant in order to simplify the dose reconstruction
process.
For instance, instead of completing a dose reconstruction which precisely estimates the worker's exposure for
cases that would most likely result in a probability of causation well below the 50% necessary for the claim to
be compensable by DOL, NIOSH will significantly over-estimate the exposure based on the highest levels of exposure
observed or possible for the facility. If the claim will not be compensable even when using these significantly
over-estimated exposure estimates, then no further refinement to the dose reconstruction is required.
This manner of dose reconstruction is called an "efficiency measure" because it allows NIOSH to issue a
timely dose reconstruction where attempts to refine the exposure estimate would not result in a compensable claim
(i.e., a full dose reconstruction would in all likelihood produce a much lower probability of causation than the
over-estimated exposure values used).
Anytime a new cancer(s) is reported to NIOSH by DOL, NIOSH is required to rework the dose reconstruction to include
the new cancer(s). If the new cancer(s) creates a potentially compensable case, NIOSH must refine the dose
reconstruction using more probable and precise exposure estimates and not the significant over-estimates as mentioned
above. These new, more accurate exposure estimates will be lower than the original estimate because we no longer
use the assumptions which overestimated the radiation dose for the cancer found in the initial dose reconstruction.
The revised radiation dose estimate may result in a probability of causation for the new cancer(s) that is lower than
the non-compensable estimate that was obtained for the first cancer using the over-estimated radiation exposure. That
is why the addition of a new cancer(s) may result in a probability of causation that is lower than the probability
found for the single original cancer. However, it is possible for additional cancer(s) to produce a full dose
reconstruction that will be determined to be compensable by DOL.
The use of "efficiency measures" and procedures for dose reconstructions that NIOSH follows under EEOICPA
are described in detail in Final Rule: Methods for Radiation Dose Reconstruction under The Act--42 CFR 82.
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Page last updated: November 3, 2008
Page last reviewed: May 30, 2008
Content Source: National Institute for Occupational Safety and Health (NIOSH)
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