Short answers, pulled from the story.
The International Agency for Research on Cancer was established on the 1st of January 1965 and is based in Lyon, France. This intergovernmental body serves as the global arbiter of truth regarding substances that turn healthy cells into malignant invaders.
The first documented case of Thorotrast-induced cancer occurred on the 1st of May 1946. Thorotrast was a suspension of thorium dioxide used as a contrast medium in x-ray diagnostics that remained trapped in various organs and emitted alpha particles for decades.
Tobacco smoke contains at least 70 known carcinogens including polycyclic aromatic hydrocarbons like benzo(a)pyrene, benzene, and nitrosamine. These compounds are implicated in the development of numerous types of cancers including lung, larynx, esophagus, stomach, kidney, pancreas, liver, bladder, cervix, colon, rectum, and blood.
Helicobacter pylori was discovered as the main causative factor in stomach cancer on the 1st of January 1982. Chronic gastritis caused by H. pylori resulted in increased production of reactive oxygen species that caused oxidative DNA damage.
The IARC Monographs on the Evaluation of Carcinogenic Risks to Humans began on the 1st of January 1971. These evaluations sort thousands of substances into four distinct groups ranging from confirmed human carcinogens to those not classifiable as to their carcinogenicity.