The bizarre case of the polluted pot
The soldiers used to climb for hours in the hot sun to reach the marijuana and opium poppies hidden in the Mexican Sierra Madre. Then they had to hack up the crop with machetes and burn it. Starting in 1975, the U.S. made their work easier by providing blue and white helicopters (Bell 212s and 206s), purchased at a cost of about $21 million; some of the helicopters were used to spray herbicides from a few feet above the ground. Others served as gun ships, hovering above to shoot it out with the peasants who took up arms to defend their crop. The program was a great success. In 1977 about 22,000 acres of poppies and 9,500 acres of marijuana plants were destroyed by the spraying in Mexico.
The chemical that most efficiently killed the poppies was an acid known as 2.4-D. The best marijuana spray was a more toxic salt, paraquat, developed by Britain's Imperial Chemical Industries; it is a poison that becomes tasteless, odorless and colorless after it is sprayed on crops. As little as one-tenth of an ounce of paraquat can kill humans who swallow it. Lesser amounts can cause scarring of the lungs, which can lead to an irreversible condition called pulmonary fibrosis. The herbicide can also cause lung hemorrhaging and vomiting.
The peasant growers of the Sierra Madre soon developed a new strategy to combat the herbicides. Paraquat kills in the sun. Its chemistry requires about three days of ultraviolet rays in order to destroy the plants on which it has been sprayed. To save the marijuana, peasants began to rush out and harvest the plants minutes after the helicopters were gone; they put their plants in bags to shield them from the sun. Even though they had been sprayed, the leaves of plants so shielded did not yellow. The plants appeared normal, so the peasants could sell them as if they were uncontaminated. The result: contaminated marijuana was mixed into the approximately 3,000 tons of Mexican pot smuggled annually into the U.S.
That posed a threat to the estimated 13 million regular users of marijuana in the U.S. Illinois Senator Charles Percy, himself no lover of marijuana, began last year to press the Government to investigate just how much contaminated marijuana was circulating in the U.S. Sampling 63 batches confiscated near the U.S.-Mexican border, the National Institute of Drug Abuse detected traces of paraquat in 13. Those findings led Health, Education and Welfare Secretary Joseph Califano to issue a public warning to marijuana smokers a month ago. Said he: "If an individual smokes three to five heavily contaminated marijuana cigarettes each day for several months, irreversible lung damage will result." There was also, he added, a "risk of lung damage for individuals who use marijuana less often or in smaller amounts."
That was enough to trigger a widespread panic. Worried marijuana smokers in Urbana, Ill., told a drug counselor that several of them had vomited and passed out after smoking pot. G.D. Searle Laboratories in Skokie, Ill., reported that 39 out of 40 marijuana samples tested had traces of paraquat. "People are running scared," says Dr. Vernon Patch, a Boston drug-abuse expert. "A situation exists which borders on hysteria," agrees the deputy director of the Illinois dangerous-drugs commission, Daniel Behnke.