Agent Orange and Porphyria Cutanea Tarda

What is porphyria cutanea tarda (PCT)?

PCT is a disorder characterized by thinning and blistering of the skin in sun-exposed areas.

Why are Vietnam veterans concerned about PCT? Does Agent Orange cause it?

Some Vietnam veterans have been diagnosed with PCT and others have expressed concern about developing this disorder. Some research has suggested that PCT may be associated with exposure to herbicides, but there is no conclusive scientific evidence that Agent Orange or other herbicides cause this condition.

What did the Veterans' Advisory Committee on Environmental Hazards conclude with regard to PCT?

During its August 22-23, 1990 meeting, the Veterans' Advisory Committee on Environmental Hazards, a VA-managed statutorily established group of independent medical and scientific authorities, found that there was no significant statistical association between exposure to a herbicide containing dioxin and the subsequent development of PCT. A majority of Advisory Committee members felt that while scientific literature, particularly that dealing with an industrial accident in Seveso, Italy, left open the possibility of an association, the existing requirement of a "significant statistical association" was not met.

What was VA's response to the Advisory Committee's finding?

Secretary Derwinski concurred. In October 1991, "final" regulations were published in the Federal Register to that effect. (See 56 Fed. Reg. 52473, October 21, 1991).

What did the National Academy of Sciences (NAS) conclude about PCT in its 1993 report, entitled, Veterans and Agent Orange – Health Effects of Herbicides used in Vietnam?

The NAS indicated that case studies and animal studies provide sufficient evidence to conclude that there is a positive association between exposure to herbicides used in Vietnam and the subsequent development of PCT in genetically susceptible individuals.

What was VA's response to the NAS 1993 finding regarding PCT?

After reviewing the NAS report and reconsidering the Advisory Committee's conclusions, VA’s Secretary Brown found that the "credible evidence for an association outweighs the credible evidence against an association." A proposed rule soliciting public comment was published in the Federal Register in September 1993. (See 58 Fed. Reg. 50528, September 28, 1993). The final rule was published in the Federal Register in February 1994. (See 59 Fed. Reg. 5106, February 3, 1994). In view of the clinical evidence that PCT onset occurs soon after exposure and consistent with manifestation periods established for many other presumptive conditions, VA established a one-year manifestation period for PCT (that is, the symptoms must have appeared within one year of last day of exposure).

What did Public Law 103-446 do for Vietnam veterans with PCT?

Section 505, Public Law 103-446, the Veterans’ Benefits Improvements Act of 1994, enacted November 2, 1994, codified (establish in law) presumptions of service connection for certain diseases -- including PCT manifested to a degree of disability of 10 percent or more within a year of military service in Vietnam -- associated with exposure to certain herbicide agents.

What did the NAS conclude about PCT in its 1996 update?

The NAS reviewers concluded that new data (not available during the 1993 review) combined with the studies reviewed in Veterans and Agent Orange justify moving PCT from NAS highest category of association (sufficient evidence of an association) to the second highest category of association (limited/suggestive evidence of an association).

How does this change impact VA policy regarding PCT?

There is no change in VA health care or compensation policy regarding PCT.

What did the NAS conclude about PCT in subsequent updates?

The 1998 update indicated that no new informative publications were identified relating PCT to exposure to herbicides or dioxin in humans. The report stated, “There is limited/suggestive evidence of an association between exposure to the herbicides considered in this report and porphyria cutanea tarda. Evidence regarding the association is drawn from occupational and other studies in which subjects were exposed to a variety of herbicides and herbicide components.”

The 2000 report, declared, “There is no basis for changing the previous conclusion that there is limited/suggestive evidence of an association between exposure to herbicides…and PCT.”

In 2002, the NAS found that there is “limited or suggestive evidence of an association between exposure to [herbicides] and PCT.”

Where can a veteran get additional information on this subject?

Information on PCT 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 veterans obtain 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 prepared in late October 2003 and does not include any subsequent developments.