"Drug safety testing (drug checking) is a public health service whereby service users receive test results for a substance of concern submitted for forensic analysis as part of a harm reduction consultation.12-14 Testing of submitted samples may be conducted onsite in rapid realtime as part of an integrated testing service, or elsewhere by a partner laboratory. Whilst these services vary widely in terms of types of consultations, forensic analyses, staffing, funding, waiting times, whether community or event-based, static or mobile, permanent or temporary, and whether the testing service is integrated or split into individual components, their shared core aim is harm reduction and their shared core service characteristic is direct user engagement. The rationale for these services is that drug-related harm can arise from the consumption of illicit psychoactive substances of unknown content and strength. Therefore, if testing services share results and other relevant information directly with service users, and potentially also other interested parties such as wider drug using communities and support services, they can communicate the risks associated with consuming that substance and enhance users' ability to make educated and informed decisions to reduce or avert future harm, protect their health and reduce the burden on health services. For stakeholders and support services, testing provides an opportunity to monitor trends in illegal drug markets and associated harms, and for alerts to be issued that are timely and accurately targeted to the appropriate drug using communities by utilising information that links composition of individual samples with what they were sold as, a distinct added value of drug safety testing.14,15 A global audit16 identified 31 such drug safety testing programmes operated by 29 organisations in 20 countries at that time, with the largest and longest standing being the Dutch Drugs Information Monitoring System,17-19 and more services have started operating since that audit."
Measham F. (2020). City checking: Piloting the UK's first community-based drug safety testing (drug checking) service in 2 city centres. British journal of clinical pharmacology, 86(3), 420–428. doi.org/10.1111/bcp.14231