People who only smoked marijuana had higher blood and urine levels of several smoke-related toxins such as naphthalene, acrylamide and acrylonitrile than nonsmokers, according to the study published Monday in the journal EClinicalMedicine.

Naphthalene is associated with anemia, liver and neurological damage, while acrylamide and acrylonitrile have been associated with cancer and other health issues.

"Marijuana use is on the rise in the United States with a growing number of states legalizing it for medical and nonmedical purposes - including five additional states in the 2020 election," said senior author Dr.

Tobacco and tobacco-marijuana smokers had higher levels of naphthalene, acrylamide and acrylonitrile than marijuana-only smokers.

At extreme levels, it can be toxic to humans following inhalation, oral or dermal exposures, according to the US Environmental Protection Agency.

Weed smokers

While weed smokers had higher amounts of naphthalene, acrylamide and acrylonitrile in blood and urine than nonsmokers, even higher levels were found in people who smoked tobacco or a combination of marijuana and tobacco.

Acrylamide is a chemical used to make paper, plastics and dyes, but is also produced when vegetables such as potatoes are heated to high temperatures.