Drugs sold on the street or under casual circumstances for illicit use are often adulterated with less expensive drug or non-drug substances. Marijuana and mescaline sold as 100% pure have shown additives of a powerful animal tranquillizer (PCP) in analysis. Drug testing services in USA estimate that half of the drugs tested are either something else altogether or doctored with other substances. Alum (toxic) is sometimes added to heroin when cheap non-toxic substances such as quinine and lactose are not available. Under casual circumstances it is relatively easy for buyers to be deceived. They may be inexperienced and ignorant about drugs. Results of adulterated drugs may be relatively harmless in the instance of a 'bad trip', although even this may have long-term psychological repercussions. However, the user runs the risk of poisoning and in very severe cases perhaps even death.