Assistant Secretary for Health James O. Mason's letter {"Elmo Zumwalt's Unfair Attack," July 4} repeats some of the some fabrications that have needlessly confused the Agent Orange debate for the past decade.

In particular, Dr. Mason states that "during the past seven years, the CDC has carried out four studies of the health effects of Agent Orange." To quote another line from Dr. Mason, "nothing could be further from the truth."

As noted in my congressional testimony and my recent report to Secretary Edward J. Derwinski of the Department of Veterans Affairs, the CDC in fact concluded, albeit quite incorrectly, that no study could be conducted on the health effects of Agent Orange. It reached this conclusion only by badly manipulating its study methodology so that no meaningful assessment of veterans exposures to the dioxin contaminants contained in Agent Orange could be derived from the CDC data. Thus, none of the CDC's studies have any relevance to the health effects of Agent Orange, save for the disingenuous titles they bear.

Those in the scientific community who were willing to look more carefully, and forthrightly, have found that Agent Orange is indeed linked to numerous cancers and other debilitating diseases. My report simply catalogues those scientific findings. It is not the work of a lonely crusader, but rather reflects the emerging view of medical and scientific opinion.

It is regrettable that what is now coming to light is clear evidence of intentional manipulation by the government and some chemical manufacturers with respect to their own dioxin studies. As a result, one cannot help but question the CDC's professed sincerity with respect to the entire Agent Orange affair. Only recently, a CDC director recommended elevated dumping levels for dioxin contaminants in contravention to the EPA's own minimal safety guidelines.

It is just this sort of indifference to recognized health effects that lead some of us to believe that there are those in the agency on a mission to subvert the true facts about dioxin contaminants. Dr. Mason would do well to distance himself from that effort. E. R. ZUMWALT JR. Arlington