Prevalence of drugs of abuse found in forensic testing of illicit drug seizures and urine samples from offenders/probationers in Hong Kong: A 3-year update

Abstract

The study investigates the prevalence of drugs of abuse detected from 2016 to 2018 through i) forensic drug testing of seizures from law enforcement agencies, and ii) common drugs of abuse for urinalysis of samples obtained from offenders/probationers under mandatory drug-use surveillance programmes. Under the selected drug testing groups, an average of 4677 cases/year (c.f. 5334 cases/year in 2011–2015) of illicit drug seizures and 19,501 samples/year (c.f. 28,438 samples/year in 2011–2015) for urinalysis, were examined from 2016 to 2018. The three most commonly encountered abused drugs in the period in both types of examinations were methamphetamine (MA), cocaine and heroin. The occurrence of ketamine, the most prevalent drug [1815 (34.0%) cases/year (for drug seizures), 2074 (7.3%) samples/year (for urinalysis)] in 2011–2015, had dropped significantly to 487 (10.4%) cases/year and 350 (1.8%) samples/year respectively. The drug positive rates for urinalysis in the selected population group (i.e., offenders/probationers requiring mandatory drug testing) increased steadily from 27.3% in 2016 to 30.8% in 2018 (an average of 29.0% vs. 22.1% in 2011–2015). The ratio of single drug use to more than one drug was about 4:1, showing predominant use of single drug. While MA was the most prevalent drug in the period, cases found with cocaine and cannabis increased steadily over the past 3 years. A rising trend was noted for cases identified with new psychoactive substances (NPS) in illicit drug seizures from an average of 87 cases/year in 2011–2015 to 211 cases/year in 2016–2018 although NPS cases still contributed to less than 5% of overall drug seizures. A total of 69 substances classified as NPS were encountered with 47 NPS newly encountered in 2016–2018 but 25 NPS found in 2011–2015 disappeared in this 3-year period. Cathinones, including both synthetic and plant-based, continued to be the major category of NPS cases (∼72%) in the region followed by synthetic cannabinoids, ketamine/PCP analogs and synthetic opioids.