Tobacco smoke, which is a well-established risk factor in bone-remodeling disorders, including osteoporosis, contains numerous environmental toxins, including polycyclic aryl hydrocarbons (PAH) such as benzo[a]pyrene (BaP) and dioxins such as TCDD; importantly, both BaP and TCDD are well-established AhR agonists [12]. The gene discussed is AHR; the disease is osteoporosis.