Explain the reason why studies of the health effects of smoking among individuals who smoke would not be a concern of environmental epidemiology. Why is exposure to secondhand cigarette smoke a concern of this discipline?

By 2 weeks after fertilization the morula has implanted into the uterine lining and transforms into a(n) . this time is when the , or the organ that will provide nourishment to the fetus by exchanging nutrients and waste products, begins to develop.