Overview
Apart from the true monogenic genetic disorders, environmental factors may determine the development of disease in those genetically predisposed to a particular condition. Stress, physical and mental abuse, diet, exposure to toxins, pathogens, radiation and chemicals found in almost all personal-care products and household cleaners are common environmental factors that determine a large segment of non-hereditary disease.
If a disease process is concluded to be the result of a combination of genetic and environmental factor influences, its etiological origin can be referred to as having a multifactorial pattern.
As an example of an environmental trigger, a component of a human's drinking water may activate (trigger) a change in a person's body. Such changes are mainly negative ones. Using this example, what is in the drinking water may affect one person entirely differently than another – someone may be affected greatly, whereas someone may not be at all.
Many cancers (osteosarcoma, etc.), along with a plethora of other diseases, are thought to be a result of environmental triggers.
Nitrates may be an environmental trigger for Alzheimer's, diabetes, and Parkinson's disease.
Environmental triggers for asthma and autism have been studied too.
Read more about this topic: Environmental Factor