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COTININE

Definition

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 from tobacco smoke.¹ Levels of cotinine are 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.

Self reported data on smoking was also collected in the National Aboriginal and Torres Strait Islander Health Survey (NATSIHS) and National Aboriginal and Torres Strait Islander Nutrition and Physical Activity Survey (NATSINPAS). The biomedical results from the NATSIHMS support the self reported data in estimating smoking prevalence rates and non-smoking persons who are potentially exposed to passive smoke in the household. For details on self reported smoking data, see the relevant Tobacco Smoking and Household and Family Characteristics chapters in this product.

The cotinine test measures the amount of cotinine circulating in the blood at the time of the test.

Population

Cotinine results were obtained for selected persons aged 18 years and over, who agreed to participate in the NATSIHMS and who provided a blood sample. Fasting was not required for this test.

Methodology

A blood sample was collected from participants and cotinine levels were measured at the Douglass Hanly Moir (DHM) laboratory.

There is no consensus on the cut off reference values for defining cotinine levels to determine the level of exposure to tobacco smoke, as there are currently a number of different methods that can be used to measure cotinine. In the NATSIHMS, cut off reference values for indicating exposure to tobacco were sourced from DHM laboratory reference ranges.

In the NATSIHMS, the following definitions were used for serum cotinine:

• No exposure to tobacco smoke, cotinine levels < 140 nmol/L
• Exposure to tobacco smoke, cotinine levels ≥ 140 nmol/L.

• Cotinine results do not confirm a specific diagnosis without consultation with a health professional.
• There are a number of different test methods for measuring cotinine, which may produce different results. The data from this topic should therefore be used with caution when comparing cotinine results from other studies using a different test method or equation.
• Cotinine levels may be present in the blood due to smoking, but can also be present due to practices such as chewing tobacco, using nicotine patches and exposure to passive smoking.
• Given these issues, it is recommended that self reported smoking estimates from Australian Aboriginal and Torres Strait Islander Health Survey: Updated Results publication be used as the prevalence measure for smoking.