Blood-based biomarkers of selenium and thyroid status indicate possible adverse biological effects of mercury and polychlorinated biphenyls in Southern Beaufort Sea polar bears

► Se and TH biomarkers in blood were examined in polar bears. ► Biomarkers were compared to blood concentrations of Hg and ΣPCB7. ► Females were more susceptible to changes in Se and TH status than males. ► Positive and negative associations among biomarkers and contaminants are discussed. ► Further study of the possible adverse biological impact of combined toxicants is warranted.