Marijuana and Paraquat

To the Editor.— Because of the news coverage of paraquat and marijuana, we wish to (1) report some data on Cannabis sativa L contaminated with the herbicide paraquat (1,1′dimethyl-4,4′ -dipyridilium dichloride) and (2) present some facts regarding marijuana with or without paraquat that will be useful to the medical science community. In late 1975 Mexico initiated a program to eradicate cannabis by spraying illicit fields with aqueous paraquat. 1 In theory this was subsequently to reduce the flow of crude drugs from cannabis. This program was intensified in 1976. It is estimated that 36 million Americans have tried marijuana 2 ; thus, any agent used chemically to control cannabis is important to a large segment of our society and medical scientists. In September 1977 we were requested by the National Institute of Drug Abuse (NIDA) to screen confiscated Mexican cannabis for paraquat. To this end, 100 samples of kilogram bricks of cannabis