To determine whether a substance increases the risk of cancer, scientists carefully review evidence from studies in people and in animals. Most often human studies involve exposures that occur at work, where exposure to potential cancer-causing substances is higher than in the community or at home.
Scientists doing this research usually look at 3 things:
Scientists consider all the scientific information to determine whether a substance causes, or could potentially cause, cancer.
When these 3 steps are followed, scientists often say they have considered the weight of scientific evidence or body of evidence.
After reviewing the scientific evidence, agencies like the World Health Organization’s International Agency for Research on Cancer and the United States National Toxicology Program draw a conclusion about the risk of cancer associated with exposure to a particular substance.
The Canadian Cancer Society provides helpful information about government income programs, financial resources and other resources available to families struggling to make sense of the personal financial burden they face.