Paraquat and marijuana: epidemiologic risk assessment.
Landrigan PJ; Powell KE; James LM; Taylor PR
Am J Public Health 1983 Jul; 73(7):784-788
The hazard to marijuana smokers from paraquat (4685147) contamination was investigated. Prevalence of paraquat contamination of marijuana was studied. Samples from 910 confiscations of the drug were examined using gas/liquid chromatography. The percentage of paraquat on marijuana leaf that passed unchanged into marijuana smoke was examined using combustion testing. Computer based epidemiologic risk assessments were undertaken to estimate potential exposure of all US smokers and those in the southwest census region to paraquat. A minimal toxic dose was estimated using available animal data. Nationally, 3.6 percent of marijuana contained detectable paraquat; 98.6 percent of the contaminated marijuana was obtained in the Southwest US. Paraquat concentrations ranged from 10 to 461 parts per million. Approximately 0.2 percent of the paraquat passed unchanged into marijuana smoke. Risk assessment projections indicated that of marijuana smokers in the US, 68.5 percent would not be exposed to paraquat in a year; 31.3 percent would inhale less than 100 micrograms (microg); and 0.1 percent would inhale 100microg or more. Only 29.4 percent of marijuana smokers in the southwest would not be exposed to paraquat in a year; 69.5 percent would inhale less than 100microg, and approximately 1 percent would inhale 100microg or more. However, marijuana users who make only one large purchase a year would have the potential to be quite heavily exposed to paraquat. It was judged that an annual dose of 500microg of inhaled paraquat could produce pulmonary damage in exposed persons, with a heightened risk of pulmonary injury in those exposed to 100 to 500microg. The authors conclude that 100 to 200 persons in the Southwest US and 150 to 300 persons nationally may have been exposed to more than 500microg of paraquat in each year from 1975 to 1979.
NIOSH-Author; Toxicology; Pulmonary-system-disorders; Chromatographic-analysis; Dose-response; Epidemiology; Inhalants; Health-hazards; Exposure-levels; Pulmonary-function
Dr. Philip J. Landrigan, Division of Surveillance, Hazard Evaluations and Field Studies, NIOSH, Robert A. Taft Laboratories, 4676 Columbia Parkway, Cincinnati, OH 45226
American Journal of Public Health