A recent study conducted at Deconess Medical Center, Boston, and reported at the World Congress on Osteoporosis in Toronto Canada (June 6, 2006) showed that a large cohort of Chinese women non smokers who were nevertheless exposed to second-hand smoke and were premenopausal had almost a three fold increase in risk for osteoporosis compared to a similar group of women not exposed to second-smoke. This group also had a 2.5-fold increase in vertebral fractures. The effect was not seen in post menopausal women, giving support to the idea that this effect might be mediated by effects on estrogen, which are known to occur. Men in this study had a 1.8 - fold increase in osteoporosis, and another study conducted in Sweden of 18-20 year old men, compared bone density of smokers to non smokers and found an approximate 5 percent decline in density for smokers. They were also able to trace this to the outer layer, the cortical bone, which surrounds the spongier inner layer the trabecular bone. This adds another tissue which suffers from the repeated exposure of cigarette smoke, whether directly or second-hand.