Environmental mutations or somatic mutations are acquired by humans when they are exposed to radiation, chemicals, and viral infections. These factors affect the DNA of individual cells, such as the Hepatitis B virus which causes the liver cells to mutate and result to hepatic carcinoma or liver cancer. Another example would be the effects of the Hiroshima bombing during World War 2. Several Japanese who survived the bombing suffered from molecular and cellular mutations that caused them to have cataracts, cancers, birth defects, infertility, etc. even years after the aftermath.