Assessment of rates of recanting and hair testing as a biological measure of drug use in a general population sample of young people

Abstract Aims: We investigate the extent of and factors associated with denial of previously reported cannabis and other illicit drug use, and assess the potential of hair testing for measuring substance use in general population samples. Design: Birth cohort study. Setting: United Kingdom, 1991–present. Participants: A total of 3643 participants who provided hair and self‐report measures of cannabis and other illicit drug use in the Avon Longitudinal Study of Parents and Children (ALSPAC) at age 18 years. Measurements: Denial of