HHS Special Exposure Cohort Designation:

Area IV Santa Susan Field Laboratory, Ventura County, California [SEC Petition 00234]

U.S. Department of Health and Human Services Designation 

of Additional Members of the Special Exposure Cohort 

under the 

Energy Employees Occupational Illness Compensation Program Act of 2000 

Designating a Class of Employees 

Area IV Santa Susan Field Laboratory

 Ventura County, California 
HHS Special Exposure Cohort Designation:

Area IV Santa Susan Field Laboratory, Ventura County, California [SEC Petition 00234]

Page 2

I. Designation

I, Sylvia M. Burwell, Secretary of the U.S. Department of Health and Human Services

(HHS), designate the class of employees defined in Section II of this report for addition to 

the Special Exposure Cohort (SEC), as authorized under the Energy Employees Occupational 

Illness Compensation Program Act of 2000 (EEOICPA), 42 U.S.C. § 7384q. 

January 6, 2017 [Signature on File] 

Date Sylvia M. Burwell

II. Employee Class Definition

All employees of the Department of Energy, its predecessor agencies, and their 

contractors and subcontractors who worked in any area at Area IV of the Santa Susana 

Field Laboratory in Ventura County, California, from January 1, 1965, through 

December 31, 1988, for a number of work days aggregating at least 250 work days, 

occurring either solely under this employment or in combination with work days within 

the parameters established for one or more other classes of employees included in the 

Special Exposure Cohort. 

III. Designation Criteria and Recommendations

Pursuant to 42 U.S.C. § 7384q, for the class defined in Section II of this report, the Secretary 

has determined, and the Advisory Board on Radiation and Worker Health (Board) has 

recommended, that

(1) it is not feasible to estimate with sufficient accuracy the radiation dose that the class

received; and

(2) there is a reasonable likelihood that such radiation dose may have endangered the

health of members of the class.

The SEC final rule states in 42 C.F.R. § 83.13(c)(1) that it is feasible in two situations to 

estimate the radiation dose that the class received with sufficient accuracy. First, the rule 

states that radiation doses may be estimated with sufficient accuracy if NIOSH has 

established that it has access to sufficient information to estimate the maximum radiation 

dose, for every type of cancer for which radiation doses are reconstructed, that could have 

been incurred under plausible circumstances by any member of the class. Alternatively, 

radiation doses may be estimated with sufficient accuracy if NIOSH has established that it 

has access to sufficient information to estimate the radiation doses of members of the class 

more precisely than a maximum dose estimate.

NIOSH determined that there is insufficient information to estimate the radiation dose of 

individual members of the class with sufficient accuracy under the two abovementioned 
HHS Special Exposure Cohort Designation:

Area IV Santa Susan Field Laboratory, Ventura County, California [SEC Petition 00234]

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situations. The Board, pursuant to 42 U.S.C. § 7384q, advised the Secretary to designate the 

class as an addition to the SEC in a letter received by the Secretary on December 12, 2016. 

IV. Designation Findings

Infeasibility of Estimating Radiation Doses with Sufficient Accuracy

The Secretary designates the class of employees covered by this report based upon the 

findings summarized below. 

• NIOSH has identified that principal sources of internal radiation exposures for members

of the proposed class included exposures from inhalation and ingestion exposures to

plutonium, uranium, mixed fission products, thorium (including associated progeny), and

americium during the processing operations.

• NIOSH determined that there are insufficient internal dosimetry data, air monitoring data,

or radiological source term data available to bound intakes of thorium (including

associated progeny) and americium for the period from January 1, 1965, through

December 31, 1988. Although there are limited monitoring data that may be applied for

these radionuclides during the period, the data do not represent all operations at Area IV.

• NIOSH determined that the principal sources of external radiation exposures for

members of the proposed class included exposures to beta particles, gamma photons, and

neutrons.

• NIOSH finds that it is feasible to reconstruct external doses for Area IV workers using

available individual dosimetry records and area monitoring surveys for reconstructing

external doses for Area IV workers.

• NIOSH finds that it is feasible to reconstruct occupational medical dose for Area IV

workers using information and methods in Dose Reconstruction from Occupationally

Related Diagnostic X-Ray Procedures (ORAUT-OTIB-0006) and the Area IV site profile

documents.

• The Board concurred with the NIOSH finding that it could not reconstruct internal

radiation exposures for the proposed class of workers for the period from January 1,

1965, through December 31, 1988.

• Pursuant to 42 C.F.R. § 83.13(c)(1), NIOSH determined that there is insufficient

information to either: (1) estimate the maximum radiation dose, for every type of cancer

for which radiation doses are reconstructed, that could have been incurred under plausible

circumstances by any member of the class; or (2) estimate the radiation doses of members

of the class more precisely than a maximum dose estimate.
HHS Special Exposure Cohort Designation:

Area IV Santa Susan Field Laboratory, Ventura County, California [SEC Petition 00234]

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• Although NIOSH found that it is not possible to completely reconstruct internal radiation

doses for the period from January 1, 1965, through December 31, 1988, NIOSH intends

to use any internal and external monitoring data that may become available for an

individual claim (and that can be interpreted using existing NIOSH dose-reconstruction

processes or procedures). Dose reconstructions for individuals employed at Area IV

Santa Susana Field Laboratory during the period from January 1, 1965, through

December 31, 1988, but who do not qualify for inclusion in the SEC, may be performed

using these data as appropriate.

• The Board concurred with NIOSH’s recommendation to add the proposed class of

workers to the SEC.

Health Endangerment

The Secretary established the health endangerment determination for the class of employees 

covered by this report based upon the findings summarized below. 

(1) Pursuant to 42 C.F.R. § 83.13(c)(3), NIOSH established that there is a reasonable

likelihood that such radiation doses may have endangered the health of members of

the class. Pursuant to 42 C.F.R. § 83.13(c)(3)(ii), NIOSH specified a minimum

duration of employment to satisfy this health endangerment criterion as “having been

employed for a number of work days aggregating at least 250 work days within the

parameters established for this class or in combination with work days within the

parameters established for one or more other classes of employees in the Cohort.”

(2) NIOSH did not identify any evidence from the petitioners or from other resources that

would establish that the class was exposed to radiation during a discrete incident likely

to have involved exceptionally high-level exposures, such as a nuclear criticality

incident, as defined under 42 C.F.R. § 83.13(c)(3)(i).

(3) The Board concurred with NIOSH’s finding that the health of the class may have been

endangered and defined the class according to the 250-workday requirement specified

under 42 C.F.R. § 83.13(c) (3)(ii).

V. Effect and Effective Date of Designation

The Secretary submits this report on the designation of one additional class to the SEC for 

review by Congress, pursuant to 42 U.S.C. §§ 7384l(14)(C)(ii) and 7384q(c)(2)(A), as 

amended by the Ronald W. Reagan National Defense Authorization Act for Fiscal Year 

2005, Pub. L. No. 108-375 (codified as amended in scattered sections of 42 U.S.C.). 

Pursuant to 42 U.S.C. § 7384l(14)(C)(ii), as amended by the Ronald W. Reagan National 

Defense Authorization Act for Fiscal Year 2005, Pub. L. No. 108-375 (codified as amended 

in scattered sections of 42 U.S.C.), the designation in this report will become effective 30 

days after the date of this report’s submission to Congress “unless Congress otherwise 

provides.” 
HHS Special Exposure Cohort Designation:

Area IV Santa Susan Field Laboratory, Ventura County, California [SEC Petition 00234]

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VI. Administrative Review of Designation

The health endangerment determination of the designation provided in this report may be 

subject to an administrative review within HHS, pursuant to 42 C.F.R. § 83.18(a). On the 

basis of such a review, if the Secretary decides to expand the class of employees covered by 

this designation, the Secretary would transmit a supplementary report to Congress providing 

the expanded employee class definition and the criteria and findings on which the decision 

was based.