The study of risk factors for youth smoking has generated a considerable body of literature and, sometimes, it seems to have created almost as much heat as it has light. A classic example has been debate about the effectiveness of controls aimed at reducing youth purchase of tobacco.1 In circumstances of controversy it is important to keep in view the aims of this tobacco-control research activity. One aim is to identify those modifiable risk factors which, either singly or in combination, have the greatest potential impact for reducing youth smoking. A second aim is to inform and guide the development of appropriate preventive strategies.

The unadjusted daily smoking prevalence rates for 15-year-old New Zealanders (5.8% for Asian students, 11.9% for European students, 28.1% for Maori) reported in the paper by Scragg, Laugesen and Robinson in this issue of the Journal,2 highlight the continuing need to address youth tobacco issues. The authors of that paper identify parental smoking, students’ pocket money, and cigarette smoking within the home as risk factors, and suggest that interventions to address these factors have the potential to significantly reduce youth smoking prevalence.

The paper by Scragg et al provides a useful opportunity to reflect on the importance of home and family risk factors for youth tobacco use – factors that, as those authors note, do not always receive the attention they deserve. It has been argued that focusing on youth smoking and targeting preventive strategies directly at youth may be less effective means of reducing youth smoking than focusing on youth indirectly, through tackling adult smoking and other factors in the social and economic environment that may have the effect of promoting or providing support for smoking.3,4

Efforts to reduce smoking in the home can be beneficial in two ways. First, they can reduce the health risks associated with exposure to second-hand tobacco smoke (SHS). Second, they have the potential to reduce youth uptake of tobacco smoking. The relations between the home environment and daily smoking by youth are complex, however. The measurement of parental smoking, alone, is not straightforward and allowance needs to be made for the diverse family environments in which many young people live; for example, it cannot be assumed that most youth live in traditional, two-parent families.

Parental attitudes towards tobacco use, particularly disapproval of smoking, have been reported as being a more robust deterrent to youth smoking than actual parental smoking behaviours.5 In addition, the use of tobacco by siblings, lack of enforced family smoking rules, and households in which other adults are permitted to smoke have been reported as risk factors for youth smoking.6 The concept of the ‘permissive home’ requires further research in the New Zealand context. The association between exposure to SHS in the home and daily smoking by youth, including a consistent dose-response effect, has been reported for a New Zealand sample where nearly 44% of Year 10 and 12 students surveyed were exposed to SHS at home.7

An important issue is the need for longitudinal studies, because they provide the best way of clearly separating potential predictors from outcomes – temporal separation being one of the classic Bradford Hill criteria for indicating causation. Certainly, parental smoking is likely to have preceded youth smoking, in time, as Scragg et al contend. Those authors acknowledge, however, the potential weakness of their cross-sectional study design such that, for example, the amount of pocket money received may have been determined by the economic demands of established smoking behaviour rather than vice versa.

Another important issue is the need to conduct comparable multivariable research, for example, with measures of both parent and peer smoking included in the predictive models. The study by Scragg et al does not include any measure of peer smoking, nor any personal factors other than sex, ethnicity and pocket money received. Differences between the findings of Scragg et al and the results of the Christchurch and Dunedin longitudinal studies highlight the need to control for known, potentially important predictors.

The issue of youth smoking is important because we know that most adult smokers became smokers in youth, often before the age of legal purchase, and that quitting is difficult once nicotine dependence has been established. Although quitting before around the age of 35 years may be the most critical goal for reducing serious negative health outcomes, once regular smoking is established most smokers continue to smoke for around forty years.8 Clearly, it would be best for young people not to take up smoking in the first place. Also, there is emerging evidence that nicotine dependence can be established early and may not involve daily smoking.9 For all of these reasons, the primary prevention of smoking among youth makes good sense.

Overall, a balanced, comprehensive tobacco-control programme is likely to be the most effective means of reducing the prevalence of youth smoking. Each component in the programme should be consistent with, and reinforce, each of the others. Among the goals of such a programme should be the implementation of known effective policies and practices, including the denormalisation of tobacco smoking, so that schools, public places and homes are smoke-free environments; high tobacco taxes; and reduced promotion and access to tobacco products. The current prevalence of youth smoking in New Zealand, particularly among Maori, should be unacceptable. Further initiatives are needed and the monitoring of smoking rates and risk factors should be continued so that the effectiveness of all interventions can be rigorously evaluated.

Author information: Anthony Reeder, Cancer Society Senior Research Fellow; Helen Darling, PhD Candidate, Social and Behavioural Research in Cancer Group, Department of Preventive and Social Medicine, University of Otago, Dunedin

Correspondence: Dr Anthony Reeder, Social and Behavioural Research in Cancer Group, Department of Preventive and Social Medicine, University of Otago, PO Box 913, Dunedin. Fax: (03) 479 7298; email: treeder@gandalf.otago.ac.nz