Arizona voters may be asked to severely limit the amount of THC that medical marijuana can contain, if the top Republican in the Arizona House of Representatives has his way.

After reading a controversial book that links marijuana use to mental illness and violence, House Speaker Rusty Bowers wants to limit medical marijuana to a THC content of only 2%. Tetrahydrocannabinol, or THC, is the chemical responsible for most of marijuana’s psychological effects.

Bowers’s House Concurrent Resolution 2045 would set the strict THC limit on marijuana and marijuana products sold in Arizona medical marijuana dispensaries. It would also mandate that the Arizona Department of Health Services develop warning labels and require the department to study the relationship between marijuana, schizophrenia and violent behavior using money gathered from the medical marijuana program.

Because voters approved the state’s medical marijuana program in 2010, major changes like those proposed in HCR2045 must be approved by voters.

There is also a separate attempt to use the state’s initiative process to let voters decide on legalizing recreational marijuana.

Bowers told the House Health and Human Services Committee Thursday that his legislation is a result of his reading “Tell Your Children: The Truth About Marijuana, Mental Illness and Violence,” a book that has been widely criticized for cherry-picking data and presenting correlation as causation.

Rep. Nancy Barto, the Republican chair of the committee, said she’d also found the book compelling, and she pushed back at claims that had been “debunked,” noting that it cited scientific studies.

However, the book by former New York Times reporter Alex Berenson has been widely condemned by the scientific community – even from those whose studies he cited as evidence.

UCLA cannabis researcher Ziva Cooper took to Twitter to dispute claims made in Berenson’s book, as one of her studies was heavily cited as evidence that marijuana causes violence and psychosis.

Additionally, 100 scholars and clinicians have signed an open letter denouncing the book as “junk science,” claiming that it infers causation from correlation.

However, Thursday’s testimony focused less on the controversial claims in Berenson’s book and how Bower’s bill would prohibit THC content for medical marijuana patients.

“I was raised in the 50s, 60s, 70s, the marijuana among my friends use, they were seen as the cool guys at school,” Bowers told the committee.

Bowers contended that marijuana of his time only had a THC content of less than 1%, but the marijuana sold now has a THC content on average of more than 25%. However, marijuana strains that contain that much THC are fairly new. Some concentrates and extracts contain much higher THC levels, however.

One mother told the committee that limiting THC would harm her 9-year-old son, whose seizures are treated with marijuana oil that has a THC level of 50%.

“I pay $1,200 a month and pay taxes on that medicine,” Brandy Williams said. If voters were to place limits on THC, she said she’d be forced to turn to the black market to meet her son’s needs.

Brittany Dial, the promotional director for Pura Earth Concentrates, said the bill would put the company out of business. Dial, a veteran and survivor of sexual abuse, said that high-concentrate marijuana vape cartridges have drastically improved her ability to cope with PTSD.

Dr. Sue Sisley, a prominent marijuana researcher, told the committee that she has not seen any issues with patients on doses of marijuana with THC levels of 9% to 12%, which are considered high doses in their studies.

“Cannabis is just like any medication, it has risks and benefits,” she said, adding that she has seen it be well tolerated by patients and sees it as generally “benign.”

Sisley added that those who are predisposed to schizophrenia can have those symptoms “ignited” by marijuana use, which is why the FDA has mandated that those with a predisposition to schizophrenia be screened out of federal marijuana studies.

Bowers told the committee that he’d be willing to remove the strict THC limits from the measure, but said he wouldn’t budge on requiring warning labels on marijuana.

“I get a prescription for my rivastatin, my statin drugs, and I get told if I eat too much, it’s not going to be good for you,” Bowers said, adding that similar warnings need to be available for medical marijuana.

The bill passed on a party-line vote, with the five Republicans voting in favor and the four Democrats in opposition. It next heads to the floor to be considered by the full House of Representatives, and must also be approved by the state Senate before being sent to the November ballot.