LSD causes chromosome damage and birth defects.

On March 17, 1967, Science published a short paper that would prove to be one of the more consequential pieces of flawed research in the history of American drug policy. Maimon M. Cohen, Michelle J. Marinello, and Nathan Back at the State University of New York at Buffalo reported that when they added lysergic acid diethylamide to cultures of human white blood cells in laboratory dishes, the cells showed elevated rates of chromosomal breaks. In a patient who had been treated with LSD over a four-year period, they found similar chromosomal abnormalities. Their conclusion, stated with appropriate scientific caution in the text, was that LSD might be capable of causing chromosomal damage.

The paper's publication in Science gave it immediate authority. Within days, the finding was on the front pages of American newspapers. The chromosomal damage claim was not merely alarming in the abstract: the specific fear it activated was that LSD users might produce children with birth defects, translating individual drug use into a form of generational harm. That fear was vivid, politically potent, and extremely difficult to walk back once it had been broadcast.

It was also poorly supported. Cohen, Marinello, and Back had used an in vitro system, cells in a dish, which was known to have different properties from cells in a living organism. They had not adequately controlled for the many other variables in the patients they studied. Several researchers who read the paper noted almost immediately that the statistical methods were weak and that the clinical case, involving a patient with a complex psychiatric history and multiple treatments, could not be attributed to LSD alone. Within months, other researchers were attempting to replicate the findings and failing. Studies using pure LSD under controlled conditions consistently found lower rates of chromosomal damage than Cohen's group had reported, and several found no damage at all.

The scientific record was moving toward a negative finding. The government and media narrative was moving in the opposite direction. The Bureau of Narcotics and Dangerous Drugs cited chromosomal damage in public materials. The claim appeared in school health curricula, in Drug Abuse Resistance Education presentations, and in federal pamphlets distributed to students and parents. It was stated as established fact by officials and educators who had no reason to doubt a finding published in the most prestigious scientific journal in the United States.

In 1971, four years after the original paper, Norman Dishotsky and colleagues at Stanford published a comprehensive review in Science, the same journal that had run the Cohen paper, examining every available study on LSD and chromosomal damage in human subjects. Their review covered 21 in vivo studies involving more than 300 subjects. The finding was definitive: pure LSD at doses typically used by humans did not produce detectable chromosomal damage. The damage that appeared in some studies was associated with contaminants, polydrug use, or methodological shortcomings rather than LSD itself. The chromosome hypothesis, the authors concluded, did not survive systematic scrutiny.

The 1971 review did not travel as widely as the 1967 paper. Corrections rarely do. The chromosomal damage claim continued to appear in drug education materials through the 1980s and beyond, repeated by teachers and counselors who had absorbed it from official sources without knowing that the evidence had largely collapsed within a few years of its initial publication. This sequence, a poorly controlled laboratory study producing a vivid, frightening claim; rapid translation into official policy; failure to replicate; and slow, incomplete retraction, is not unique to LSD research. But it played out with unusual clarity in a context where the stakes, for the people being warned, were high.