RT Journal Article SR Electronic T1 Active smoking, secondhand smoke exposure and serum cotinine levels among Cheyenne River Sioux communities in context of a Tribal Public Health Policy JF Tobacco Control JO Tob Control FD BMJ Publishing Group Ltd SP 570 OP 576 DO 10.1136/tobaccocontrol-2019-055056 VO 29 IS 5 A1 Elena R. O'Donald A1 Curtis P. Miller A1 Rae O'Leary A1 Jennifer Ong A1 Bernadette Pacheco A1 Kathryne Foos A1 Kendra Enright A1 Marcia O'Leary A1 Patricia Nez Henderson A1 Johnnye Lewis A1 Esther Erdei A1 Jeffrey A. Henderson YR 2020 UL http://tobaccocontrol.bmj.com/content/29/5/570.abstract AB Introduction American Indians and Alaska Natives face disproportionately high rates of smoking and secondhand smoke (SHS) exposure. The Cheyenne River Sioux Tribe (CRST) is among the few Tribal Nations controlling commercial tobacco exposures in public and work places. We had an opportunity to explore effects of the new commercial tobacco-free policy (implemented in 2015) in an environmental health study (2014–2016) that collected information about commercial tobacco use and SHS prevalence and examined predictor variables of serum cotinine concentrations.Methods Self-reported survey data were used in quantile regression statistical modelling to explore changes in cotinine levels, based on smoking status, smokeless tobacco consumption and SHS exposure.Results From enrolled 225 adults, 51% (N=114) were current smokers. Among 88 non-tobacco users, 35 (40%) reported current SHS exposure. Significant differences in cotinine median concentrations were found among participants with and without current SHS exposure. Extremely high cotinine concentrations (~100 times larger than the median) were detected in some non-tobacco users. After implementing the new smoke-free air Tribal policy, cotinine decreased in participants with intermediate (3–15 ng/mL, non-tobacco users with SHS exposure) and high (>15 ng/mL, mainly tobacco users) cotinine levels showing association with an abatement of opportunities for SHS exposure. Significant predictors of cotinine levels were sampling year, current smoking and tobacco chewing. No gender differences were observed in cotinine.Conclusions Our results show decrease in cotinine concentrations in CRST participants since implementation of their ‘Smoke-Free Clean Air Act’ in 2015.