There are well documented acute and chronic effects of cannabis use on mental functioning. However, less is known about any effects on cognition within the context of work and everyday life. The aim of the study was to examine any association between cannabis use and cognitive performance, mood and human error at work. Cannabis users and controls completed a battery of laboratory based computer tasks measuring mood and cognitive function pre- and post-work at the start and end of a working week. They also completed daily diaries reporting their work performance. Cannabis use was associated with impairment in both cognitive function and mood, though cannabis users reported no more workplace errors than controls. Cannabis use was associated with lower alertness and slower response organization. In addition, users experienced working memory problems at the start, and psychomotor slowing and poorer episodic recall at the end of the working week. This pattern of results suggests two possible effects. First a 'hangover'-type effect which may increase with frequency of use. Second a subtle effect on cognitive function, perhaps more apparent under cognitive load and/or fatigue, which may increase with more prolonged use. The results also highlight the importance of the timing of testing within the context and routine of everyday life.

A large number of workers experience accidents and minor injuries at work. Minor injuries are not recorded by official sources but could have implications in productivity and worker health. Factors identified in this study, as associated with injuries or accidents, could be addressed by specific workplace policies or by raising individual awareness of the risks.

Information about cognitive failures is important in the study of accidents and injuries at work. In addition, negative job characteristics represent part of the context in which human error is translated into injury.

This study aimed to examine demographic, lifestyle, mental health and personality factors associated with illicit recreational drug use, heavy alcohol consumption and smoking in a community-based population sample. A postal questionnaire survey was conducted of people who were selected at random from the Electoral registers of Cardiff and Merthyr Tydfil. Illicit drug use was associated with risk taking, neuroticism, being male, having a higher education qualification, not being married, being unemployed, being aged under 25 years, smoking, heavy alcohol consumption and living in Cardiff. Smoking was associated with anxiety, depression, being female, lower income and educational qualifications, looking after the family or home, being aged over 25 years, illicit drug use and heavy alcohol use. Heavy alcohol consumption was associated with not being depressed, experiencing sleeping problems, risk taking, being male, higher income, no higher educational qualification, not being married, being a student, being aged under 25 years, smoking and illicit drug use. Illicit drug use, smoking and heavy alcohol use were strongly associated with each other. Illicit drug use was associated with alcohol use and, to an even greater extent, with smoking. Illicit drug and alcohol use were associated with similar characteristics, but smoking was associated with a rather different demographic combination.

The findings lend support to the SSRIs comparative safety, even among workers, particularly as the symptoms of the underlying psychopathology are successfully addressed. Possible memory impairments may, however, be found in those taking SSRIs.