This ground-breaking study, published in the journal Carcinogenesis, was conducted by several hundred scientists from around the world.  They sought to assess the carcinogenic potential of low-dose exposures to chemical mixtures in the environment.

Ten “Hallmarks” of cancer–breakdowns in biological systems that allow the formation of tumors–had been previously identified.  The hypothesis of the Halifax Project is that the same biological mechanisms by which many known carcinogens cause cancer can also be achieved through the combined effects of multiple chemicals.  The scientists explored whether low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to carcinogenesis.

In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis.

The Hallmarks of Cancer, originally described in the scientific literature by Hanahan and Weinberg, define the ten common characteristics of all cancers.  They are:

1. The cells in cancer have become genetically unstable;
2. They are frequently found in an inflammatory environment;
3. They are growing uncontrollably;
4. They are able to avoid/ignore anti-growth signalling;
5. The cells have a self-destruct mechanism that is not functioning properly;
6. The cells have bypassed a replication limit that is not functioning properly;
7. The metabolic machinery with the cells is not functioning normally;
8. The cancerous cells are able to evade immune system surveillance;
9. Cells that are oxygen-deprived within a tumor will signal for new blood flow; and
10. Malignant cancerous cells invade nearby tissues, and ultimately enter the blood stream or lymph system, which allows them to spread and colonize in other parts of the body.