Image copyright Getty Images Image caption The hashish obtained in Madrid was found to contain dangerous levels of E.coli bacteriaCannabis resin sold on the streets of Madrid is contaminated with dangerous levels of faecal matter, a study says.
They found that 93% of the acorn-shaped samples contained dangerous levels of E.coli bacteria, as did 29.4% of the ingot samples.
Some 10% of the cannabis samples were also contaminated with Aspergillus, a dangerous fungus that can cause serious health problems.
The study says this is particularly dangerous for cancer patients, who sometimes smoke cannabis to help with the symptoms of chemotherapy.
There are three main types of street cannabis – hash, herbal cannabis (weed, grass or marijuana) and high-potency cannabis or skunk.