AGENT ORANGE AND NON-HODGKIN'S
LYMPHOMA
What are non-Hodgkin's lymphomas?
The term "non-Hodgkin's lymphoma" is used to describe a group
of malignant tumors that affect the lymph glands and other lymphatic
tissue. These tumors are relatively rare (about 3% of all cancers that
occur among the U.S. general population), and although survival has
improved during the past 20 years, these diseases tend to be fatal.
What prompted initial concerns among Vietnam veterans about non-Hodgkin's
lymphomas?
The possibility that exposure to phenoxy herbicides such as Agent Orange
may have caused rare forms of cancer in humans was suggested in Swedish
studies published in 1979 and 1981. Investigations in Sweden reported
a six-fold increased risk of malignant lymphomas (Hodgkin's disease
and non-Hodgkin's lymphomas combined) among persons occupationally exposed
to phenoxy herbicides or chlorophenols compared to persons without exposure.
Have more recent results supported or conflicted with these Swedish
studies?
An analysis using the New Zealand Cancer registry indicated an elevated
risk of malignant lymphomas (including non-Hodgkin's lymphomas, Hodgkin's
disease, and multiple myeloma) linked with agricultural occupations;
however, further analyses restricted to interviews of non-Hodgkin's
lymphoma and control subjects found no significant differences between
non-Hodgkin's lymphoma cases and controls regarding their potential
exposure to phenoxy herbicides or chlorophenols.
A population-based study in Kansas found a 6-fold excess risk of non-Hodgkin's
lymphomas among farmers exposed to herbicides more than 20 days per
year (regardless of the number of years of herbicide use) compared to
non-farmers. Excess risk of non-Hodgkin's lymphomas in Kansas were associated
primarily with long-term use of the herbicide 2,4-D, one of the ingredients
of Agent Orange. (This was not the ingredient of Agent Orange which
contained TCDD or dioxin which has caused a variety of illnesses in
laboratory animals.) Hodgkin's disease was not associated with herbicide
use in Kansas.
A study in Washington State demonstrated small but significantly increased
risks of developing non-Hodgkin's lymphomas in association with some
occupational activities where phenoxy herbicides have been used in combination
with other types of chemicals, particularly for long periods. The study
results did not demonstrate an association between increased cancer
risks and exposure to any specific phenoxy herbicide product alone.
A1987 study of Swedish pesticide appliers, 72% of whom were exposed
also to phenoxy herbicides, found no excess risk of non-Hodgkin's lymphomas
or Hodgkin's Disease.
Conflicting results have also been seen in studies of Vietnam veterans.
No significant excess mortality from non-Hodgkin's lymphomas was reported
among New York State Vietnam veterans, Australian Vietnam veterans,
U.S. Vietnam veterans in the Centers for Disease Control (CDC) Vietnam
Experience Study or among Air Force "Ranch Hands" who handled
and sprayed herbicides in Vietnam. West Virginia Vietnam veterans had
an excess of deaths from Hodgkin's disease compared to non-Vietnam veterans.
In a mortality study of U.S. Army and Marine Corps veterans, a significantly
higher than expected proportion of non-Hodgkin's lymphomas occurred
among U.S. Marine Vietnam veterans, compared to Marines who did not
serve in Vietnam. When Marine Vietnam veterans were compared with all
non-Vietnam veterans combined (Army and Marine), there was no excess
of non-Hodgkin's lymphoma deaths. Non-Hodgkin's lymphomas were not elevated
among Army Vietnam veterans included in the same study. Army veterans
who served in the same geographical area (I Corps) as the Marines experienced
no excess of deaths due to non-Hodgkin's lymphomas.
The CDC Selected Cancers Study suggested that Vietnam veterans are at
increased risk of developing this disease, but the excess was confined
to men who served in the "blue-water" Navy. A VA study published
in the Journal of Occupational Medicine in July 1991 indicated that
military service in Vietnam did not increase the risk of developing
non-Hodgkin's lymphomas.
Does VA recognize non-Hodgkin's lymphomas as service-connected for
Vietnam veterans?
Yes. On March 29, 1990, Secretary Derwinski announced that VA would
service-connect non- Hodgkin's lymphomas based on service in Vietnam.
This announcement was prompted by release of results of the CDC Selected
Cancers Study which indicated that Vietnam veterans are at increased
risk of developing non-Hodgkin's lymphomas. CDC found no evidence that
the increased risk was due to Agent Orange. Final regulations implementing
Secretary Derwinski's decision were published in the Federal Register
in October 1990. (See 55 Fed. Reg. 43123, October 26, 1990).
What did Public Law 102-4, the Agent Orange Act of 1991, do for Vietnam
veterans with non-Hodgkin's lymphoma?
Section 2, Public Law 102-4, enacted February 6, 1991, established by
statute the presumption of service connection for certain diseases including
non-Hodgkin's lymphoma manifested to a degree of 10 percent or more
-- associated with exposure to certain herbicide agents.
In July 1992, a proposed rule implementing the presumptions established
by this law was published in the Federal Register for public comment.
(See 57 Fed. Reg. 30707, July 10, 1992). In May 1993, the rule was finalized
and published in the Federal Register. (See 58 Fed. Reg. 29107, May
19, 1993).
What did the National Academy of Sciences (NAS) conclude about non-Hodgkin's
lymphomas (NHL) in its 1993 report, entitled Veterans and Agent Orange
- Health Effects of Herbicides Used in Vietnam?
The 832-page NAS report contained the following statements:
The production studies suggest an increased
risk of NHL from exposure to TCDD-contaminated chemicals, but not
of a degree that would allow a definitive statement to be made....
Thus, taken as a group, the studies
of agricultural and forestry workers suggest that there is an association
between exposure to herbicides (including 2,4-D) and NHL
Although no single (veterans)
study shows definite associations between NHL and exposure to herbicides
since individual exposures were not determined except for Ranch Hands,
none rules out the possibility that an herbicide-related risk of NHL
existed for some military personnel during service in Vietnam....
Thus, unlike most of the other cancers
studied by the committee for which the data do not distinguish between
the effects of herbicides and TCDD, the available epidemiologic data
suggest that the phenoxy herbicides, including 2,4-D; rather than
TCDD may be associated with non-Hodgkin's lymphomas....
Evidence is sufficient to conclude
that there is a positive association between exposure to herbicides
(2,4-D; 2,4,5-T and its contaminant TCDD; cacodylic acid; and picloram)
and non-Hodgkin's lymphoma.
What did the NAS conclude about non-Hodgkin's lymphomas in its 1996
update?
The NAS indicated that "recent scientific literature continues
to support the conclusion that there is a positive association between
exposure to herbicides and non-Hodgkin's lymphoma."
Where can a veteran get additional information regarding non-Hodgkin's
lymphomas?
Information on non-Hodgkin's lymphomas and related matters can be obtained
at VA medical center libraries, from the Registry Physician at VA medical
centers, or from the Environmental Agents Service (131), Department
of Veterans Affairs, 810 Vermont Avenue, N.W., Washington, DC 20420.
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Agent
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