AGENT
ORANGE AND RESPIRATORY CANCERS
What
are respiratory cancers?
Respiratory
cancers refers to carcinomas of the lung, larynx, trachea, and bronchus.
Why
are Vietnam veterans concerned about respiratory cancers?
Does Agent Orange cause them?
Many
Vietnam veterans have been diagnosed with a respiratory cancer and others have
expressed concern about developing such a cancer. Respiratory cancers are now the leading causes of cancer
death in the United States. Some
research has suggested that respiratory cancers may be associated with exposure
to herbicides, but there is no conclusive scientific evidence that Agent Orange
or other herbicides cause these conditions.
What
did the Veterans' Advisory Committee on Environmental Hazards conclude with
regard to respiratory cancers?
In May
1991, the Advisory Committee considered approximately forty studies dealing with
lung cancer. The Committee observed
that most of the studies failed to adequately consider exposure documentation
and potential confounding factors, particularly smoking.
The only study, considered by the Advisory Committee, to address the
factor of smoking was negative with regard to lung cancer.
The Advisory Committee concluded that, on the basis of available
epidemiological data, there is no evidence of a significant statistical
association between exposure to herbicides containing dioxin and lung cancer.
What
was VA's response to the Advisory Committee's finding?
On June 27,
1991, Secretary Derwinski found that sound medical and scientific evidence does
not establish the required association. On
January 21, 1992, the Federal Register published a proposed rule
that would have added lung cancer to the list of "diseases not associated
with exposure to herbicides containing dioxin."
The January 21 proposal was never finalized.
(See 57 Fed. Reg. 2236, January 21, 1992).
What
did the National Academy of Sciences (NAS) conclude about respiratory cancers in
its 1993 report, entitled Veterans and Agent Orange – Health
Effects of Herbicides Used in Vietnam?
The NAS
found "limited/suggestive evidence" -- a category it defined as
meaning that evidence suggests an association between herbicide exposure and a
specific disease, but that chance, bias, and confounding factors cannot be ruled
out with confidence -- of association between herbicide exposure and the
subsequent development of respiratory cancers (including cancers of the lung,
larynx, trachea, and bronchus).
What
was VA's response to the NAS finding?
In
reviewing the NAS report, which noted that not all studies had fully controlled
for or evaluated smoking as a confounding factor, VA gave weight to the fact
that the studies found relatively high risks for respiratory cancers in
production workers. VA also noted
that despite the failure of some to control for smoking, it is unlikely that
there were major differences in smoking patterns between the study and control
groups.
Considering
all the evidence, VA’s Secretary Brown determined that the credible evidence
for an association outweighs the credible evidence against an association
between exposure to herbicides used in Vietnam and the subsequent development of
respiratory cancers. Based on
existing scientific evidence, a thirty-year manifestation period was
established, that is, cancer had to occur within thirty years of exposure.
The
proposed rule regarding respiratory cancers was published for public comment in
the Federal Register in February 1994.
(See 59 Fed. Reg. 5161, February 3, 1994).
The final rule was published in the Federal Register in June 1994.
(See 59 Fed. Reg. 29723, June 9, 1994).
What
did Public Law 103-446 do for Vietnam veterans with respiratory cancers?
Section
505, Public Law 103-446, the Veterans’ Benefits Improvement Act of 1994,
enacted November 3, 1994, codified (established in law) presumptions of service
connection for certain diseases -- including respiratory cancers (cancer
specifically and only of the lung, bronchus, larynx, or trachea) manifest to a
degree of 10 percent or more within 30 years of military service in Vietnam.
What did
Public Law 107-103 do for Veterans with respiratory cancers?
Section 201, Public law 107-103 eliminates the 30-year limitation on the period during which respiratory cancers must become manifest for services connection (and disability compensation) to be granted on a presumptive basis.
What
did the NAS conclude about respiratory cancers in subsequent updates?
In the 1996
report, the NAS noted that among the many epidemiological studies of respiratory
cancers reviewed, positive associations were found consistently only when TCDD
(dioxin) or herbicide exposures appeared to be both high and prolonged.
This was “especially true in the largest, most heavily exposed cohorts
of chemical production workers exposed to TCDD.”
The NAS commented that studies of farmers tended to show a decreased risk
of respiratory cancers (perhaps due to lower smoking rates), and studies of
Vietnam veterans were inconclusive. The
report concluded that the evidence for this association was limited/suggestive
rather than sufficient, because of the “inconsistent pattern of positive
findings across populations with various degrees and types of exposure” and
because the most important risk factor -- cigarette smoking -- was not fully
controlled for or evaluated in all studies.
In the 1998
update, with regard to laryngeal cancer (one form of respiratory cancer), the
report states the following:
Studies
published since Update 1996 continue to support the conclusion that there is
limited/suggestive evidence of an association.
The committee concluded that the evidence for this association was
limited/suggestive rather than sufficient because of the inconsistent pattern of
positive findings across populations with varying degrees and types of exposure
and because the most important risk factors for laryngeal cancers--cigarette
smoking and alcohol consumption--were not fully controlled for or evaluated in
the studies.
With regard
to lung and trachea cancer, the report states the following:
In summary, the most recently published studies continue to support the placement of lung and trachea cancer in the category “limited/suggestive evidence of an association.” Several studies suggest a higher rate of these cancers in individuals with known exposure to phenoxy herbicides or dioxin, and there is some evidence of a dose-response relationship. Whereas smoking undoubtedly plays a role in these cancers, the consistency of the finding across several studies argues against the notion that it is the sole explanatory factor.
In 2000,
with regard to laryngeal cancer, the NAS report states the following:
There is no
information contained in the research for this report to change the conclusion
that there is limited or suggestive evidence of an association between exposure
to herbicides (2,4-D, 2,4,5-T and its contaminant TCD, cacodylic acid, and
picloram) and laryngeal cancer.
With regard
to lung, trachea and bronchus cancer the report states the following:
A growing
body of research supports the conclusion that there is limited/suggestive
evidence of an association between exposure to herbicides (2,4-D, 2,4,5-T and
its contaminants TCDD, cacodylic, and picloram) and cancer of the lung,
bronchus, and trachea.
With regard to laryngeal cancer, update 2002 states that there is no
reason to change the conclusion that there is limited or suggestive evidence of
an association between exposure to herbicides and laryngeal cancer.
With regard to lung, trachea and bronchus cancer, the update states that
there is limited or suggestive evidence of an association to herbicides and the
aforementioned cancers.
Where
can a veteran get additional information on this subject?
Information
on respiratory cancers and related matters can be obtained at VA medical center
libraries, from the Environmental Health Clinician at every VA medical center,
or from the Environmental Agents Service (131), Department of Veterans Affairs,
810 Vermont Avenue, N.W., Washington, DC 20420.
Where can a veteran get additional information regarding Agent Orange – related issues?
The following
Agent Orange Brief fact sheets (including the one you are reading) are available
on the World Wide Web at www.va.gov/AgentOrange:
A1.Agent Orange - General Information; A2.Agent
Orange Class Action Lawsuit; B1.Agent
Orange Registry Program; B2.Agent
Orange – Health Care Eligibility; B3.Agent
Orange and VA Disability Compensation; B4.VA
Information Resources on Agent Orange and Related Matters; C1.Agent Orange – The Problem Encountered in Research; C2.Agent
Orange and Vietnam Related Research – VA Projects; C3.Agent
Orange and Vietnam Related Research – Non-VA Projects; D1.Agent Orange and Birth Defects; D2.Agent Orange and Chloracne; D3.Agent
Orange and Non-Hodgkin’s Lymphoma; D4.Agent
Orange and Soft Tissue Sarcomas; D5.Agent
Orange and Peripheral Neuropathy; D6.Agent
Orange and Hodgkin’s Disease; D7.Agent
Orange and Porphyria Cutanea Tarda; D8.Agent
Orange and Multiple Myeloma; D9.Agent
Orange and Respiratory Cancers; D10.Agent
Orange and Prostate Cancer; D11.Agent
Orange and Spina Bifida; D12.Agent
Orange and Diabetes; and D13.Agent Orange and Chronic Lymphocytic
Leukemia. Hard copies can be obtained
from local VA medical centers or from the VA Central Office at the Environmental
Agents Service (131) Department of Veterans Affairs, 810 Vermont Avenue, N.W.,
Washington, DC 20420.
At the same Web site you will find copies
of past and current issues of the “Agent Orange Review” newsletter and other
items of interest.
This
fact sheet was updated in late October 2003 and does not include any subsequent
developments.