Cannabis ‘Vaping’Concerns California Pesticide Regulators

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By David Schultz

Sept. 20 — California environmental regulators are increasingly concerned that people who consume cannabis using a vaporizer are ingesting concentrated and potentially dangerous amounts of pesticides, according to a state official.

George Farnsworth, an assistant director in the state’s Department of Pesticide Regulation, said his office’s toxicologists are beginning to examine how the effects of consuming pesticide residues on cannabis differ depending on the methods used to ingest it.

Pesticide regulators in states that have legalized cannabis are still struggling to set the acceptable limits of pesticide residue on the plant, a task typically performed by the U.S. Environmental Protection Agency. Because federal drug laws prohibit the EPA from conducting pesticide risk analyses on marijuana, states have resorted to basing their limits from other crops that are consumed in a similar way, such as tobacco or hops.

But vaping makes this task even more difficult, Farnsworth told a Sep. 20 meeting of state pesticide regulators. Few if any other agricultural crops are regularly consumed this way, so almost no data exist on the effects of inhaled pesticide vapor, he said.

Cannabis has been legal in California for medical uses since 1996. Four states and the District of Columbia have legalized the drug for nonmedical use. Voters in five additional states, including California, will decide on similar legalization measures this fall through ballot initiatives.

To contact the reporter on this story: David Schultz in Washington at

To contact the editor responsible for this story: Larry Pearl at

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