Objectives To assess the association between secondhand smoke exposure and blood lead and cadmium concentration in women in South Korea.

Design Population-based cross-sectional study.

Setting South Korea (Korea National Health and Nutrition Examination Survey V).

Participants 1490 non-smoking women who took part in the fifth Korea National Health and Nutrition Examination Survey (2010–2012), in which blood levels of lead and cadmium were measured.

Primary outcome measures The primary outcome was blood levels of lead and cadmium in accordance with the duration of secondhand smoke exposure.

Results The adjusted mean level of blood cadmium in women who were never exposed to secondhand smoke was 1.21 (0.02) µg/L. Among women who were exposed less than 1 h/day, the mean cadmium level was 1.13 (0.03) µg/L, and for those exposed for more than 1 h, the mean level was 1.46 (0.06) µg/L. In particular, there was a significant association between duration of secondhand smoke exposure at the workplace and blood cadmium concentration. The adjusted mean level of blood cadmium concentration in the never exposed women's group was less than that in the 1 h and more exposed group, and the 1 h and more at workplace exposed group: 1.20, 1.24 and 1.50 µg/L, respectively. We could not find any association between lead concentration in the blood and secondhand smoke exposure status.

Conclusions This study showed that exposure to secondhand smoke and blood cadmium levels are associated. Especially, there was a significant association at the workplace. Therefore, social and political efforts for reducing the exposure to secondhand smoke at the workplace are needed in order to promote a healthier working environment for women.