EXPOSURE TO TOBACCO SMOKE

The National Aboriginal and Torres Strait Islander Health Measures Survey (NATSIHMS) included a test for cotinine as an objective measure of smoking status. The body produces cotinine in the process of breaking down, or metabolising, nicotine.¹ Given that most nicotine comes from exposure to tobacco smoke, cotinine levels are assumed to be generally proportionate to the amount of tobacco exposure a person receives through smoking, or in some cases, through exposure to second hand smoke. However, cotinine levels only remain elevated for around 20 hours after exposure to tobacco smoke, therefore it can only provide a measure of short-term exposure.

Data source and definitions Levels of cotinine were measured via a blood test. In the NATSIHMS, cotinine levels of 140 nmol/L or greater indicate exposure to tobacco smoke.

The 2012–13 Australian Aboriginal and Torres Strait Islander Health Survey (AATSIHS) showed that 44.4% of Aboriginal and Torres Strait Islander adults self-reported being a current daily smoker.²

As for the non-Indigenous population, the pattern across age for Aboriginal and Torres Strait Islander people for cotinine levels of 140 nmol/L or more were very similar to that for the self-reported smoking data. Although small gaps were evident, none of these were significant.


As expected, the majority (95.4%) of Aboriginal and Torres Strait Islander adults who self-reported being current smokers had cotinine levels indicating exposure to tobacco smoke. Interestingly, however, 13.9% of those who self-reported being an ex-smoker had levels of cotinine indicating exposure to tobacco smoke, as did 6.0% of those who self-reported having never smoked. This pattern was the same for both men and women. Overall, these discrepancies were much higher than those found in the non-Indigenous population, where only 5.7% of ex-smokers and 0.3% of those who had never smoked had cotinine levels of 140nmol/L or more.

This difference was particularly noticeable for Aboriginal and Torres Strait Islander people living in remote areas, where 22.5% of non-smokers had levels of cotinine indicating exposure to tobacco smoke. One potential explanation for this could be the use of chewing tobacco. Chewing tobacco is not included in the self-reported smoking rates, yet according to the AATSIHS, around 2.2% of Aboriginal and Torres Strait Islander people living in remote areas chewed tobacco daily. The NATSIHMS showed that of those non-smokers in remote areas who had cotinine levels greater than or equal to 140nmol/L, around one in five (19%) reported chewing tobacco daily.

Other possible reasons for the discrepancy include the use of nicotine in some smoking cessation programs (e.g. nicotine patches), which would raise the level of cotinine in the blood, or high levels of exposure to second hand smoke. It is also possible that people's smoking behaviours changed between the time they self-reported their smoking status and the time they provided their biomedical sample.

For more information on cotinine, see Table 5 on the Downloads page of this publication.



ENDNOTES

1 Benowitz, NL, 1996, Cotinine as a Biomarker of Environmental Tobacco Smoke Exposure, Epidemiologic Reviews <http://epirev.oxfordjournals.org/content/18/2/188.citation>,
2 Australian Bureau of Statistics, June 2014, Australian Aboriginal and Torres Strait Islander Health Survey: Updated Results, 2012–13, ABS cat. no 4727.0.55.006 <https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/4727.0.55.006~2012–13~Main%20Features~Tobacco%20smoking~13>, Back to top