The smoke from burning marijuana leaves contains several known carcinogens and the tar it creates contains 50 percent more of some of the chemicals linked to lung cancer than tobacco smoke. A marijuana cigarette also deposits four times as much of that tar as an equivalent tobacco one. Scientists were therefore surprised to learn that a study of more than 2,000 people found no increase in the risk of developing lung cancer for marijuana smokers.

"We expected that we would find that a history of heavy marijuana use--more than 500 to 1,000 uses--would increase the risk of cancer from several years to decades after exposure to marijuana," explains physician Donald Tashkin of the University of California, Los Angeles, and lead researcher on the project. But looking at residents of Los Angeles County, the scientists found that even those who smoked more than 20,000 joints in their life did not have an increased risk of lung cancer.

The researchers interviewed 611 lung cancer patients and 1,040 healthy controls as well as 601 patients with cancer in the head or neck region under the age of 60 to create the statistical analysis. They found that 80 percent of those with lung cancer and 70 percent of those with other cancers had smoked tobacco while only roughly half of both groups had smoked marijuana. The more tobacco a person smoked, the greater the risk of developing cancer, as other studies have shown.

But after controlling for tobacco, alcohol and other drug use as well as matching patients and controls by age, gender and neighborhood, marijuana did not seem to have an effect, despite its unhealthy aspects. "Marijuana is packed more loosely than tobacco, so there's less filtration through the rod of the cigarette, so more particles will be inhaled," Tashkin says. "And marijuana smokers typically smoke differently than tobacco smokers; they hold their breath about four times longer allowing more time for extra fine particles to deposit in the lungs."

The study does not reveal how marijuana avoids causing cancer. Tashkin speculates that perhaps the THC chemical in marijuana smoke prompts aging cells to die before becoming cancerous. Tashkin and his colleagues presented the findings yesterday at a meeting of the American Thoracic Society in San Diego.

5 Comments

1. 1. Getbusyliving 02:50 PM 4/6/08

   Nice.

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2. 2. JUAN CARLOS 12:44 AM 3/28/09

   SOY UN FUMADOR ASIDUO Y EXAGERADO DE MARIHUANA . LLEVO FUMANDO UNOS 22 AOS A RAZON DE % A / TRONCHOS POR DIA...NO FUMO TABACO...ME DA MUCHO MIEDO EL RIESGO DE CANCER...POR ESO NO VOY AL DOCTOR...SOLO SIENTO UNA TOSESITA CONSTANTE...ME GUSTARIA QUE ME ESTUDIEN A FONDO COMO MUESTRA REPRESENTATIVA DEL PROBLEMA....CARLOS COBEA...LIMA, PERU

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3. 3. ctu420 02:45 AM 3/3/11

   Marijuana is one of the safest drugs known to man. Not even a single overdose has ever been documented. It should be legal and taxed just as alcohol and tobacco are.
   To learn about marijuana and to take courses for entry into the booming medical marijuana industry i recommend going to Cannabis Training University. Cannabis Training University offers medical marijuana growing courses, medical marijuana laws and regulations, how to start your own medical marijuana dispensary, and many more industry leading courses at affordable rates.

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4. 4. ashka 09:43 AM 12/15/11

   This finding has been known for a long time yet the media seem to be rather slow of all the medical discoveries in recent decades which all back up history with regards to medical cannabis use. Denying people this wonderful medicine is against our human rights and has to end now. How can we claim to be civilized and compassionate people when we allow sick people to keep suffering.

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5. 5. KuroGroves 04:55 PM 9/23/12

   Cannabis CURED my cancer. This is my story. http://www.youtube.com/watch?v=cZfWglJ2wmU I documented everything. Google David Triplett and cancer. Google CBD and Cancer. Go to kurogroves.com to learn more. Cannabis does indeed cure cancer.

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