DAVIS – Researchers at UC Davis are warning some medical marijuana users after identifying potentially lethal bacteria and mold on cannabis samples from 20 Northern California dispensaries.

Related Articles TheCannifornian.com California cannabis site launches Microbiology professor George Thompson is advising those with weakened immune systems to avoid vaping or smoking marijuana.

Thompson says leukemia, lymphoma, AIDS or cancer patients who use contaminated cannabis could put themselves at risk of lung infections.

Patients with lowered immune systems are typically told to avoid cut flowers and unwashed fruits or vegetables because they may harbor potentially harmful bacteria and mold, or fungi. Thompson says marijuana also belongs in that group.

Researchers say the risk of infection is low for the majority of medical marijuana users.

The Sacramento Bee reported Tuesday (http://bit.ly/2kSB2EV ) that the study’s findings are in the journal Clinical Microbiology and Infection.