Limited available research on maternal marijuana use has prompted many health organizations to discourage moms from using cannabis. (Thinkstock/Getty Images)

Tokin’ questions: Is pot safe for pregnant moms? Does marijuana cause lung cancer?

Third in a series. Read Part 1 and Part 2

A pregnant woman has morning sickness so severe she can’t keep food down, so she stirs some cannabis-infused oil into her morning tea to regain her appetite.

An elderly man has chronic pain that keeps him up at night, so he smokes marijuana most nights before he and his wife go to bed.

There’s a growing body of research that suggests marijuana can help with conditions such as nausea and pain while posing only modest health risks for adults. But as Californians get ready to vote Nov. 8 on whether to legalize recreational marijuana, there are broader public health questions to consider, from whether it affects developing fetuses to the impact of secondhand smoke.

“We often hear there are no negative effects,” said Kevin Alexander, who works with addicts at Hoag Hospital’s ASPIRE program in Newport Beach. “But we need more research and information on how it would affect us as a community and the societal impacts.”

The Register is continuing a series that surveys research and interviews experts on common questions about marijuana use: the potential health risks, issues of government regulation and the experience of states where recreational cannabis is legal.

Q. Is cannabis dangerous for pregnant women?

A. There’s no level of marijuana use that’s considered “safe” for women who are pregnant or breastfeeding, per the experts, just as there’s no safe level of alcohol, tobacco or many other substances.

While expectant moms report using marijuana to ease severe morning sickness, the American College of Obstetricians and Gynecologists recommends they stop using cannabis until they’re finished breastfeeding.

“Although we still need more research on the topic, the data we do have raises concerns regarding negative effects of marijuana on the growing fetus,” said Dr. Joseph Wax with the organization.

Research published in the journal Psychopharmacology found that even low doses of marijuana in pregnant rats produced offspring with learning delays plus tremors and unusual emotional behavior.

A 2010 study by researchers out of the University of Pittsburgh studied children at 10 years old who’d been exposed to marijuana during pregnancy. They found these children were more likely to miss school and show early signs of depression and attention disorders.

The Pittsburgh study’s authors pointed out that they couldn’t say how environment or family might play into that equation, though, noting it’s possible that a mother who smoked marijuana while pregnant simply passed along a predisposition for risky behavior.

More research is underway. But the American Medical Association feels there’s enough evidence of risk to push for this warning on all marijuana products: “Marijuana use during pregnancy and breastfeeding poses potential harms.”

Q. Does smoking marijuana cause lung cancer?

A. The cancer link appears increasingly weak, though more research is needed.

Marijuana contains many compounds also found in tobacco, including some known to cause cancer. That’s triggered reports suggesting that smoking marijuana must be more dangerous, since it’s typically inhaled more deeply and held in the lungs longer than tobacco.

However, the research so far suggests otherwise.

A comprehensive 2014 study published in the International Journal of Cancer found “little evidence for an increased risk of lung cancer,” even among heavy or long-term cannabis smokers. Those results are buoyed by a number of other large studies, including an examination out of UCLA in 2006 that was funded by the National Institute on Drug Abuse.

One possible explanation is that marijuana users typically don’t smoke as often as tobacco users.

Dr. Donald Tashkin, a pulmonologist who led the UCLA study, suggested marijuana doesn’t pose the same cancer risk as tobacco because THC, the psychoactive compound in cannabis, has been found to slow the growth of some cancers.

THC is known to reduce inflammation, too, Tashkin points out, which may explain why there also doesn’t appear to be a link between marijuana and chronic obstructive pulmonary disease, which plagues cigarette smokers.

Several studies have shown a correlation between heavy marijuana smoking and other respiratory conditions, such as chronic bronchitis.

There’s an alternative, advocates say: Don’t smoke it. While edibles and concentrates come with their own set of risks, lung issues aren’t among them.

Q. Is secondhand pot smoke dangerous?

A. The jury is still out, but experts say best to avoid it if possible.

First, there’s the potential – albeit a small one – for a “contact high.”

Nonsmokers who were in a car or other small, unventilated space with heavy marijuana smokers showed some of the same temporary minor memory and coordination problems as the smokers themselves, according to a study out of Johns Hopkins University School of Medicine. Some exposed nonsmokers even tested positive for the drug.

Those are considered extreme conditions. The National Institute on Drug Abuse notes that a contact high is highly unlikely, since very little THC is exhaled into the air.

The more serious concern is whether secondhand pot smoke poses the same deadly risks as exposure to secondhand tobacco smoke. That’s where the science isn’t settled, though research largely points to no.

As Tashkin’s studies above show, even firsthand marijuana smoke doesn’t seem to pose an increased risk of lung cancer or chronic pulmonary obstruction disease as cigarette smoke.

However, a 2014 study on rats by cardiovascular researcher Matthew Springer at UC San Francisco found secondhand marijuana smoke restricts blood vessels much like tobacco smoke. That can increase chances of a heart attack, particularly for people who have other risk conditions.

California law says medical marijuana patients can’t smoke in areas where tobacco is banned or within 1,000 feet of school or youth centers. The proposed recreational use initiative bans consumption in public or around children.

To be safe, experts recommend making sure there’s good ventilation if you’re around marijuana smokers. Or suggest other methods of consumption, such as vaporizing, edibles or tinctures.

Contact the writer: 714-796-7963 or or on Twitter @JournoBrooke

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