If, for instance, all the people who die in smoking- related diseases were to die when they smoked their first cigarette, cigarettes would be considered extremely dangerous and would be banned in all societies. No one would be allowed to even touch a cigarette without very strict safety measurements. But since there is a time delay of decades from the start of smoking and the occurrence of lung cancer it is very hard to see the connection. Two people in the same place could be exposed very differently due to behavior. The parents, who are at the same place, do not get the same exposure.
Human behavior has a strong bearing on exposure to different risk factors.
This also means that we can avoid risk factors if we have the knowledge. As indicated above there are many exposures, diseases and genetic factors that can be discussed. This book deals with a number of examples in order to increase the understanding of how complex our lives are in terms of environmental risk factors. These examples are presented in the 18 chapters of this book. Water quality is discussed in two chapters which deal with algae toxins and substances formed by chlorination of drinking water.