Diseases are often due to multiple factors, meaning that not only the relevant gene but also environmental factors are responsible for trait expression. Using a susceptibility test, it is possible to determine intolerance of a particular substance. Such tests may provide an individual with important information that has a bearing on their choice of profession and workplace. For example, a person may exhibit intolerance to a certain chemical. They should not therefore engage in an occupation that may involve contact with this substance. In this context, then, a susceptibility test can help uncover potential health risks.