Scientists find health threat from marijuana and tobacco smoke

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In a new study, researchers have found health risks of chemicals in tobacco and marijuana smoke.

They found that people who smoked only marijuana had several smoke-related toxic chemicals in their blood and urine, but at lower levels than those who smoked both tobacco and marijuana or tobacco only.

Two of those chemicals, acrylonitrile and acrylamide, are known to be toxic at high levels.

They also found that exposure to acrolein, a chemical produced by the combustion of a variety of materials, increases with tobacco smoking but not marijuana smoking and contributes to heart disease in tobacco smokers.

The findings suggest that high acrolein levels may be a sign of the increased risk of heart disease and that reducing exposure to the chemical could lower that risk.

The research was conducted by a team at Dana-Farber Cancer Institute and the Centers for Disease Control and Prevention.

Marijuana use is on the rise in the United States with a growing number of states legalizing it for medical and non-medical purposes—including five additional states in the 2020 election.

The increase has renewed concerns about the potential health effects of marijuana smoke, which is known to contain some of the same toxic combustion products found in tobacco smoke.

In the study, the team involved 245 HIV-positive and HIV-negative participants in three studies of HIV infection in the United States.

(Studies involving people with HIV infection were used because of high tobacco and marijuana smoking rates in this group.)

The researchers collected data from participants’ medical records and survey results and analyzed their blood and urine samples.

Combining these datasets enabled them to trace the presence of specific toxic chemicals to tobacco or marijuana smoking and to see if any were linked to an increased risk of heart disease.

The team found that participants who exclusively smoked marijuana had higher blood and urine levels of several smoke-related toxic chemicals such as naphthalene, acrylamide, and acrylonitrile metabolites than non-smokers did.

However, the concentrations of these substances were lower in marijuana-only smokers than in tobacco smokers.

They also found that acrolein metabolites—substances generated by the breaking down of acrolein—were elevated in tobacco smokers but not marijuana smokers.

This increase was linked to heart disease regardless of whether individuals smoked tobacco or had other risk factors.

The findings suggest that high acrolein levels may be used to identify patients with increased heart risk.

Reducing acrolein exposure from tobacco smoking and other sources could be a strategy for reducing risk.

One author of the study is Dana Gabuzda, MD.

The study is published in EClinicalMedicine.

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