"In July 2009, the US Drug Enforcement Agency (DEA) reported that 69% of cocaine entering the US contained levamisole"
https://www.health.ny.gov/diseases/aids/general/opioid_overdose_prevention/health_advisory_levamisole-contaminated_cocaine.htm
"the U.S. Substance Abuse and Mental Health Services Administration (SAMHSA) made the surprising announcement that levamisole had been found in "over 70 percent of the illicit cocaine analyzed [by the DEA] in July."
https://erowid.org/chemicals/cocaine/cocaine_article2.shtml
"Levamisole is estimated by the Drug Enforcement Agency (DEA) to be present in about 80% of cocaine seized in the United States"
https://pubmed.ncbi.nlm.nih.gov/24440755/
"The concentration of levamisole in cocaine has steadily increased since it was first detected. The concentration was less than 1% in 2001,8 and in 2009, levamisole comprised approximately 10% of each cocaine sample.8 By July 2009, the DEA reported that 69% of cocaine entering the United States contained levamisole,9 while in the United Kingdom, levamisole was found in over 50% of cocaine samples tested.7 In an analysis of cocaine users in Seattle, Washington, approximately 80% of users who tested positive for cocaine also tested positive for levamisole.4 Levamisole is also used to adulterate other illicit substances; seized heroin supplies in 2008 and 2009 were found to contain trace amounts of levamisole"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3498128/
"It’s a well-known and established fact that a high percentage of street cocaine is laced with levamisole, a veterinary drug used to deworm animals."
https://skywoodrecovery.com/cocaine-cut-with-dangerous-levamisole/