Carcinogenicity

Although both man-made and naturally occurring chemicals can have many adverse (and even fatal) health effects, the effect of most concern to many is the development of a cancer. When considering that in many parts of the world cancer is the second most frequent cause of death, this concern is not surprising. Cancer is not a new phenomenon, and nor is the implication of chemicals in being a factor involved in the aetiology of this dreadful disease.

In fact, as far back as the Eighteenth Century, certain occupations (although it was in fact chemicals) were recognised as aetiological factors in human carcinogenesis. As a result 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 term 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 is derived 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 factor 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.