Part 2: Toxicity—Chemical Carcinogenesis


Carcinogenesis is a word used to describe the process of cancer formation. A carcinogen is anything that causes cancer. The process of cancer formation can be broken down into five distinct steps:
1. Initiation: The genetic information (DNA) in a healthy cell is irreversibly damaged
2. Promotion: Spread of the mutated genes is initiated either by increased cell division or inhibition of apoptosis. As new cells form, they also contain the mutated DNA.
3. Conversion: Further genetic changes occur transforming the cells into a malignant phenotype
4. Progression: The malignant phenotype expands through growth of malignant cells
5. Metastasis: The cancer spreads from the site of initiation to other parts of the body
  • Exogenous exposure. This involves exposure to carcinogens that are present in food, water, the air, etc. Examples include: tobacco smoke, sunlight (UV radiation), certain fungi, and free radicals.
  • Endogenous exposure. This involves a carcinogen that is produced naturally by the body. Although our bodies are highly effective, they are not perfect and will occasionally produce a carcinogen during normal metabolic processes. The body has efficient ways of “cleaning up” metabolic mistakes, but it can become a problem if the metabolic machinery becomes permanently dysfunctional (for example if mitochondria are damaged). Other examples of endogenous carcinogens are errors in DNA replication, production of estrogen metabolites, and chronic inflammation.
Although most essential oils are very safe, some should never be used or consumed. For example, sassafras essential oils should not be used because of its high level of safrole, a constituent that has been demonstrated to be carcinogenic. Other oils with high levels of known carcinogenic constituents are calamus (contains the constituent asorone), yellow camphor (contains the constituent safrole), brown camphor (contains the constituent safrole), and wormwood (contains the constituent thujone). It is important to be aware that other varieties of camphor, particularly white camphor, are safe and non-carcinogenic.