... ammonia and formaldehyde, leave the body quickly and do not accumulate at all. Other chemicals are stored in the body for long periods. For instance, lead is stored in the bone, cadmium is stored ... chemical. Many things determine how an individual will react to a chemical. These include age, sex, inherited traits, diet, pregnancy, state of health, and use of medication, drugs, or alcohol. Depending ... in humans is due to exposure to a particular substance, since exposure may have occurred many years before, and people are exposed to many different substances.Since the study of cancer in...