Carcinogenicity and Chemicals
Although both man-made and naturally occurring chemicals can have many adverse (and even fatal) health effects, the effect of primary worry to many is the development of a cancer. When considering that in many countries of the world cancer is the second most common cause of death, this concern is not surprising. Cancer is not a new occurrance, and nor is the implication of chemicals in being a factor involved in the aetiology of this often fatal disease.
In fact, as far back as the 18th Century, certain occupations (although it was in fact chemicals) were recognised as aetiological factors in human carcinogenesis. As a outcome of the public perception of cancer, chemical carcinogens are subject to special laws and regulations which essentially restrict their use and thereby human exposure to them.
The Collins English Dictionary (1991) defines Cancer as “Any type of malignant growth or tumour, caused by abnormal and uncontrolled cell division”. The word Carcinogenesis is derived from the Greek word “Karkinos” which means crab like and “gennan” which means “to produce”. This carcinogenesis means the creation of cancer and carcinogens are those agents which cause cancer.
The word Neoplasm derives from “neo” (new) and “plasm” (growth). It is simply another word for tumour or growth. Neoplasms can be classified as benign or malignant. A benign neoplasm is typically localised and non invasive. It does not metastase (spread to other parts of the body). A malignant neoplasm on the other hand is invasive, non-structured and it has the propensity to metastasise.
There is a wide variety of causative agents implicated in the development of cancer. It is widely believed that lifestyle, that is the use of tobacco, alcohol, diet, sunbathing, etc. is one of the most important factors involved.
One of the main problems with trying to define the cause of cancer is the relatively long latency period of the disease. This is the time between the initiation of the carcinogenic process by a carcinogen, to the development of the clinical symptoms of a pre-malignant or malignant tumour. This makes it very difficult to backtrack and pin point the causative agents, which may themselves act independently or in combination.
Another very important element implicated in the development of cancer is the exposure to carcinogens in the work place. As it is estimated that up to 8% of all human cancers are occupational in origin, this factor should be taken very seriously.
Laura Robinson is an author, expert witness and toxicologist based in West Sussex, UK.