Is THC a Health Risk to Pregnant Women? California Just Decided It Is

Scientists appointed by Gov. Gavin Newsom voted on Wednesday to put both cannabis smoke and THC — the psychoactive compound in marijuana — on the state's list of "reproductive toxicants."

The panel of scientists with the California Office of Environmental Health Hazard Assessment (OEHHA) met in Sacramento to wrestle with the reliability and accuracy of dense research studies, and to consider whether to declare marijuana's potent, high-inducing chemical a health risk to pregnant women and require warnings for pot products legally sold in California.

Surveys have indicated that a rising number of mothers-to-be have turned to marijuana products for relief from morning sickness and headaches, though its effectiveness has not been backed by science.

The panel's finding means THC will now join hundreds of other chemicals judged to cause cancer or birth defects that California requires to carry warning labels, such as arsenic and lead.

But don't expect to see developmental toxicity warnings for expectant mothers on cannabis just yet.

"There is a one-year grace period before any warnings are required, and several things could happen in that one-year period," said Sam Delson, deputy director of OEHHA. "One, we can seek to determine a level of exposure that does not cause a significant health risk and therefore does not require warnings. We can also work to develop special warnings that address the unique characteristics of these substances and the specific health effects."

The panel delved into numerous studies examining whether cannabis use during pregnancy can be linked to low birth weight, early deliveries, infant mortality or cognitive or other health problems with children.

They debated whether studies were sufficiently comprehensive and scientifically sound to make judgments about the effects of THC and pregnancy. Some studies didn't make clear how frequently a mother used cannabis during pregnancy or what products were being used. Others didn't account for instances when mothers were using marijuana and tobacco, and whether that could skew the results.

Because some studies included only tests on animals, such as mice or rats, the panel discussed whether those results could be used to consider the effects on people. In other cases, studies relied on self-reporting by new mothers, putting the reliability of the information in doubt.

Cannabis industry officials say too little sound research is available on THC to support the panel's move, and warn that it could make marijuana companies a target for lawsuits with unverified claims of injuries from pot use during pregnancy.

“That seems like an open-ended checkbook. How do we defend ourselves?" said Los Angeles dispensary owner Jerred Kiloh, who heads the United Cannabis Business Association, an industry group.

The review was carried out under the umbrella of the Safe Drinking Water and Toxic Enforcement Act, better known as Proposition 65. It requires warning labels for chemicals judged as dangerous and allows residents, advocacy groups and attorneys to sue on behalf of the state and collect a portion of civil penalties for failure to provide warnings.

The 1986 law has been credited with weeding out cancer-causing chemicals from products but also faulted for setting the stage for legal shakedowns.

Lawyers looking for a quick buck will say "give us $10,000 or we are going to take you into a long court case," Kiloh said.

The California Cannabis Industry Association echoed that fear, noting that pot's standing as an illegal drug at the federal level has choked off research by government agencies. Those studies are needed to determine if THC poses health risks for pregnant women, the group said.

“Good policy and consumer protections are based on facts and data,” spokesman Josh Drayton said.

Since 2009, California has listed marijuana smoke as being known to cause cancer, similar to tobacco smoke.

The U.S. surgeon general warned in August that smoking marijuana is dangerous for pregnant women and their developing babies. Mainstream medicine advises against pot use in pregnancy because of studies suggesting it might cause premature birth, low birth weight or other health problems, but many of those studies were in animals or had findings that were open to dispute.

The National Institute on Drug Abuse is paying for several studies on marijuana use during pregnancy.

Now that the California panel has declared pot a risk for pregnant women, it's not clear what the immediate impact will be on the state's legal pot industry.

Presumably, packaging will need to be changed over time to carry warning labels for pregnant women. But such requirements would likely take additional steps by agencies that oversee marijuana regulation and packaging.

Even products containing CBD, a trendy ingredient extracted from marijuana or hemp, can contain trace amounts of THC.

This post includes reporting from The Associated Press's Michael R. Blood, and KQED's Peter Jon Shuler and David Marks.