Dr. Helpern's associate, Deputy Chief Medical Examiner Baden, went on to further discredit the already implausible overdose theory at a joint meeting of two American Medical Association drug-dependency committees held in Palo Alto, California, in February 1969.
"The majority of deaths," Dr. Baden told the AMA physicians, "are due to an acute reaction to the intravenous injection of the heroin-quinine-sugar mixture. This type of death is often referred to as an 'overdose,' which is a misnomer. Death is not due to a pharmacological overdose in the vast majority of cases."
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One theory sometimes advanced is that Syndrome X deaths are caused by the quinine in the bag. Quinine was introduced as an adulterant of heroin sometime after 1939, when an epidemic of malaria spread by contaminated injection needles hit New York City addicts 40 thus the time of introduction fits the Syndrome X timetable. Some addicts discovered that the quinine contributed to the sensation known as a "rush" immediately after injection. Heroin traffickers also discovered that the bitter taste of the quinine makes it impossible for addicts to gauge the concentration of heroin in the bag by tasting the mixture. For these and possibly other reasons, quinine has remained a standard adulterant of New York City heroin ever since.
Perhaps the first suggestion that quinine might be causing New York City's Syndrome X deaths came from Dr. F. E. Camps, the United Kingdom Home Office pathologist in charge of investigating opiate deaths in England. At a conference of the Society for the Study of Addiction held in London in September 1966 (which Chief Medical Examiner Helpern attended), Dr. Camps stated: "The only comparable drug to heroin which causes rapid death with pulmonary edema is quinine. In this case patients start off with discomfort in their chest, and then rapidly die. It is conceivable that this could have some relation to [New York City] heroin deaths ."
At the same conference an American pathologist, the late Dr. Rudolph J. Muelling of the University of Kentucky Medical School, added that a type of lung lesion similar to that found in Syndrome X deaths "is found to occur when one studies pure quinine cases. In the United States this kind of lesion has been found in several nurses attempting to induce abortions on themselves. They take the quinine orally and the condition comes on quite rapidly. The patients die of quinine alone."