| Summary: | Background
Cotinine
is a widely-used biomarker of exposure to tobacco for both active and
second-hand smoke (SHS). Given South Africa's tobacco control laws restricting
smoking in public places in the last decade, we assessed the prevalence and
extent of exposure to tobacco by socio-demographic characteristics, smoking
status, and exposure to SHS in the home.
Methods
Data was analysed from the South African National Health and Nutrition
Examination Survey. Interview and serum cotinine biomarker data were collected.
A cotinine cut-off point of 10 ng/ml for no tobacco exposure was used in the
South Africa context, and values over 300 indicated heavy tobacco smoking.
Weighted multiple logistic and linear regressions were used to determine the
factors associated with the presence and level of cotinine.
Results
Cotinine
was detected in 63.3% of individuals aged ≥15 years (n=4621), where 28.4% had values
of ≤10 ng/ml, 22% had 10-300 ng/ml, and 12.9% above 300 ng/ml. Mean cotinine
was 252.6 [235.7-269.5] for current smokers and 237.9 [197.8-278.0] for
smokeless tobacco users. Among current smokers, mixed race ethnicity and being
male were significantly associated with higher levels of cotinine whereas mean
cotinine did not vary by exposure to SHS at home. Tobacco exposure (>10
ng/ml) was found in 18.7% of never users of any tobacco product. Among never
users, the odds of tobacco exposure were significantly (p< 0.05) higher for
those exposed to SHS in their homes (OR=1.59), for males (1.56), African (2.16)
and mixed race (2.23) ethnic groups, older ages, those residing in rural formal
areas (2.57), and in low income (2.27) and intermediate income (1.66)
households.
Conclusions
The findings provide insight into
the factors associated with tobacco exposure. A substantial number of never
users had cotinine in their blood, which calls for increased tobacco control
efforts to protect people from the harmful effects of tobacco smoke.
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