Traces of highly potent opioids known as nitazenes have for the first time been found to be consumed by people who use drugs in Africa, according to a report released Wednesday by the Global Initiative Against Transnational Organized Crime, a nonprofit organization.

Nitazenes, powerful synthetic opioids, have long been in use in Western countries as well as in Asia where they have been associated with overdose deaths. Some of them can be up to 100 times more potent than heroin and up to 10 times more potent than fentanyl, meaning that users can get an effect from a much smaller amount, putting them at increased risk of overdose and death.

The report focused on Sierra Leone and Guinea-Bissau and is based on chemical testing of kush, a derivative of cannabis mixed with synthetic drugs like fentanyl and tramadol and chemicals like formaldehyde. Researchers found that in Sierra Leone, 83% of the samples were found to contain nitazenes, while in Guinea-Bissau it was identified in 55%.

“The GI-TOC ( Global Initiative Against Transnational Organized Crime) believes that these results are the first indication that nitazenes have penetrated retail drug markets in Africa,” the report said.

Many young people in West and Central Africa have become addicted to drugs with between 5.2% and 13.5% using cannabis, the most widely used illicit substance on the continent, according to the World Health Organization.

In Sierra Leone where kush is one of the most widely consumed drugs, President Julius Maada Bio this year declared war on the substance, calling it an epidemic and a national threat.

Nitazenes have been detected repeatedly in substances sold to young people in the region such that users are most likely ingesting them “without knowing the risks they face,” Wednesday’s report said.

The authors said their findings suggest that nitazenes are being imported into Sierra Leone from elsewhere and that the substance being sold as kush in Guinea-Bissau was of similar chemical composition to that found in Freetown.

Officials in the two countries must deploy chemical testing equipment as a first step in tackling drug abuse, the report said. “Without this, it is impossible for the government of Sierra Leone, Guinea-Bissau and the wider subregion to accurately monitor the countries’ illicit drug markets and develop evidence-based responses,” it said.