evidence: Immune System Suppression "First, they said poppers caused AIDS. Then in 1983 the federal Public Health Service printed a booklet that said nitrites didn’t cause immune system suppression. In 1985 they revise the booklet to say ‘don’t use inhalants.’ No wonder there is so much confusion," said Wilson, who has spearheaded the effort in California to place restrictions on their sale. [...] And the debate is heating up in California, where county supervisors in San Francisco and Los Angeles and the City Council in West Hollywood are considering similar actions. The Los Angeles board Tuesday is expected to order a study on a recommendation of the Public Health Commission to ban sales of poppers, according to aides of Supervisor Edmund D. Edelman. [...] In early 1981, when the AIDS epidemic began, doctors noticed almost all the victims used poppers. With not much else to go on, they first believed that the chemicals might be the cause. But that theory dissolved when the HTLV-III virus was isolated in 1984. However, because 90% of those exposed to the AIDS virus do not develop AIDS, the search for co-factors--social or medical conditions that make some more susceptible to contracting the disease--continues.