Chemical mixtures and human health
In our everyday life, we are exposed to many chemicals. But, in reality, we are exposed not to single chemicals but to mixtures of chemicals. So the effect of mixtures will be different from that of single chemicals. The effect may be additive or non-additive. In certain cases, the mixture of chemicals will have a synergistic effect. In a nutshell, the effects of mixtures on human health are very complex and studies are still being carried out on this.
That chemicals cause many diseases on human beings is a known fact. For example, Arsenic causes skin cancer, asbestos, lung cancer and the list is a long one. But again, human beings are exposed to mixtures of chemicals, the effect of which is still unexplored. Infinite combinations of chemicals are possible and it is very difficult to understand which combination is powerful. Hence the study of chemical mixtures is a very difficult one and it is a 'sunrise' science.
As man's innovations and industrialization have accelerated in the last 100 years, his exposure to more number of chemicals has also increased dramatically. Man's exposure to hydrocarbons and their by-products is a result of development of fossil fuels. Pharmaceutical industry and the chemical industry contribute heavily to such exposure. Pesticides, Herbicides and fungicides used for crops add to this. Use of platics is another grave step which has increased this exposure to a great extent. According to reports, there are about 80,000 chemicals which are being used at present and many of these chemical compounds are yet to be adequately tested for human toxicity.
Chemicals can interact in a number of ways. Since they interact in many ways, their effects are complex to study. There may be different actions on different parts of the body like kidney, the liver or the brain. But the major concern stems from the fact that there is a possibility of these chemicals having synergistic and more than additive effects.
Exposure to chemical mixtures may be through inhalation, ingestion or through skin and the route of exposure determines the site of its effect. To quote an example, smoking leads to lung cancer, application of mutagenic substances on the skin results in skin cancer, etc. But in the case of more persistent contaminants, the route of exposure is an insignificant determinant.
Considering the highly harmful nature and hazardous effects on human health and environment, designing new approaches to study the complex nature of chemical mixtures needs immediate attention.