Study: Marijuana smoke 3 times worse for you than tobacco smoke


Exposure to marijuana smoke is three times more harmful than exposure to tobacco smoke, new research suggests.

Matthew Springer, a professor at University of California, San Francisco School of Medicine, studied the effects of smoke on rats and found exposure to secondhand marijuana smoke makes it harder for arteries to expand and allow a healthy flow of blood.

Springer's research involved putting a lit cigarette or marijuana joint in a plexiglass box with anesthetized rats. When exposed to tobacco smoke, the rats' arteries had difficulty expanding for about 30 minutes. However, when exposed to marijuana smoke, the arteries took about 90 minutes to return to their normal function.

"People think cannabis is fine because it's 'natural,'" Springer told NPR. "I hear this a lot. I don't know what it means."

He said tightly controlled marijuana, which has been tested, has less chemicals than cigarettes. However, any smoke is bad for the lungs, heart and blood vessels.

Springer said people shouldn't think of the research "an anti-THC conclusion," referencing the active ingredient in marijuana, rather "an anti-smoke conclusion."

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Legal recreational marijuana sold in California
Customers buy recreational marijuana at the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson
Marijuana is displayed for sale at the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson
A customer browses marijuana products for sale at the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson
Customers queue for recreational marijuana outside the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson
A customer browses screens displaying recreational marijuana products for sale at the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson
A woman holds marijuana for sale at the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson
Marijuana edibles are displayed for sale at the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson
Eron Silverstein, 51, (R) shops for marijuana at the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson
Marijuana products are displayed for sale at the MedMen store in West Hollywood, California U.S. January 2, 2018. REUTERS/Lucy Nicholson
Customers purchase marijuana at Harborside, one of California's largest and oldest dispensary dispensaries of medical marijuana, on the first day of legalized recreational marijuana sales in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
People wait in line at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana sales in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
A customer waits at the counter to purchase marijuana as others wait in line at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
Andrew DeAngelo (L) and his brother Steve DeAngelo (R), co-founders of Harborside, one of California's largest and oldest dispensaries of medical marijuana, celebrate after a ceremonial ribbon cutting on the first day of legalized recreational marijuana in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
An employee hugs a customer as others wait in line at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
An employee finds marijuana for a customer at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
Employees wait behind the counter at Harborside, one of California's largest and oldest dispensaries of medical marijuana, as a large clock counts down to the store's official opening at 6am on the first day of legalized recreational marijuana in Oakland, California, U.S. January 1, 2018. REUTERS/Elijah Nouvelage
Different strains of marijuana are seen for sale at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
A couple poses behind a cardboard Instagram frame while waiting in line at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
Employees prepare to open at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
Steve DeAngelo (C) makes the first legal recreational marijuana sale to Henry Wykowski at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana sales in Oakland, California, U.S. January 1, 2018. REUTERS/Elijah Nouvelage
Michael Sherman purchases marijuana at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana sales in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
A customer peers at different marijuana strains in a glass case at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
Marijuana is seen for sale at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana sales in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage
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Plenty of research has been done on the effects of secondhand tobacco smoke, but little is known about long-term effects of secondhand marijuana smoke, making Springer worry the lack of research makes people think secondhand marijuana smoke is OK.

"We in the public health community have been telling them for decades to avoid inhaling secondhand smoke from tobacco," Springer told NPR. "We have not been telling them to avoid inhaling secondhand smoke from marijuana, and that's not because it's not bad for you – it's because we just haven't known. The experiments haven't been done."

The rise of e-cigarettes and vaping devices also worries him. Although they may seem like good alternatives to avoid inhaling smoke and producing secondhand smoke, Springer warns they could contain harmful chemicals of their own. He is currently researching the health effects of those chemicals as well.

Copyright 2017 U.S. News & World Report

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