Tourists looking to take in Spain’s cannabis culture should probably skip on buying hashish from Madrid’s illegal street dealers.

According to a study published in the journal Forensic Science International, “The majority of the hash sold in the Madrid region is not apt for human consumption, mainly due to microbiological criteria, and it represents a danger for health,” researchers conclude.

Pérez Moreno, a pharmacist from the veterinary faculty of Madrid’s Complutense University, and his research team collected 90 different samples of cannabis resin sourced from dealers on the street in different neighborhoods throughout Madrid. They found that 75 percent of the analyzed samples contained large quantities of the E.coli bacteria, which is an indication of fecal contamination.

Researchers blame certain practices involved in drug trafficking, namely the act of smuggling product by swallowing pellets of hash – referred to as “bellotas,” or acorns – in plastic film. “When they get to Spain, they take a laxative and expel the bellotas,” Moreno explains. “And then they’re put on sale.”

Forty percent of the bellotas examined also bore the smell of feces.

“This is clearly a public-health problem,” added biologist Inmaculada Santos, co-author of the study. “The quantities of bacteria that we found are appalling. The problem is not just inhalation. Hashish is constantly manipulated [by users] with their hands.”

Advocates of cannabis reform believe that these findings are even more reason to bring cannabis legalization to Spain.

“This type of contamination is down to the fact that hashish is illegal in Spain,” said psychologist Claudio Vidal to El País. “In a regulated market, that would be unthinkable.”

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