1 Public Health and Regulatory Policy, Centre for Addiction and Mental Health, Toronto, ON M5S 2S1, Canada; Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; Epidemiological Research Unit, Klinische Psychologie & Psychotherapie, Technische Universität, Dresden, Germany. Electronic address: jtrehm@aol.com.
2 Alcohol & Drug Abuse Research Unit, Medical Research Council, Cape Town, South Africa; Department of Psychiatry, Stellenbosch University, Tygerberg, South Africa.