Toxicology deals with the science of poisons. Chemicals/substances which are toxic in nature are present in the environment and find their way to the organisms through food chain, contact or respiration. The lower doses of these chemicals get accumulated in the body tissues and impair the growth/function while their higher doses are lethal. The human environment gets affected through these chemicals when they become part of the food chain. Soil-water-plant-animal activities are resulting in environmental degradation in form of deforestation, erosion, silting up of reservoirs, wastelands, air, soil and water pollution and desertification. Changing land uses, faulty irrigation systems, excessive use of chemicals in agriculture are causing the problems of soil and water pollution, toxic residues in food items and resource degradation. This in turn affects land productivity and human health.
Technological development and economic growth have brought about a rapid increase in the production of a variety of chemicals including pesticides for use in agriculture, industry and public health. This has brought countless benefits to our society in a way to improve our living standards, food production and sanitation. These man-made chemicals while on one hand are beneficial, also cause hazards to men and environment. With increasing stress on industrial and agricultural expansion programmes, in both developed and developing countries, the environmental risks of these chemicals on animal and plant life are also increasing at threatening rate as more than 1000 new molecules are introduced into the environment every year. The emergence of these chemicals and their environmental consequences have lead to the evolution of new branch of science, generally known as environmental toxicology which include the hazardous effects that these toxins have on humans, other animals and plants.
The toxicological studies on these chemicals in different laboratories of the world have established the hazardous potential of carcinogenicity, mutagenicity and teratogencity of some of the commonly used chemicals in agriculture and industry. A few of them have also been found to cause injury to immune system causing immuno-toxicological problems leading to depleting competence of the living organisms to mount resistance to viral, bacterial and fungal infections, In fact, immunotoxicological processes may be a basis of well documented toxic and allergic hypersensitivities as well as a myriad of disease entities of unknown etiology including autoimmune disorders and malignancy.
Lester Brown of World Watch Institute in 1997 cautioned that all the basic indicators of food security, grain production per person, carry over stock of grain, area of croplands signal a tightening situation during 1990’s Growth in food production is slowing with the grown in demand, driven by population growth and the rising affluence continues to be strong. The population growth is a big challenge. Stabilizing climate means reducing carbon emissions and hence fossil fuel burning. Improving energy efficiency is equally important. Securing future food supplies will affect every facet of human existence from land use policy to water use policy. Environmental concerns will have over riding priority if a healthy human life is the goal. He further states that environmental disruption could disrupt the economic progress.
Human Life Style and Environment
Modern life style with sufficient food, comfort, luxury, leisure and changed cultural habits also introduces in the environment thousands of chemicals, machinery and equipment’s. The polluted surroundings are the bonus. In addition to disastrous effect on environment, the environmental pollutants may have direct effect on human health which may be again acute in the long term. The long term effect cannot be known immediately, it is expressed only after long time of the exposure and this is of great human concern. Long term health effect lead to induction of genetic damage and/or cancer caused by environmental pollutants associated with some of our modern life style. Here mutagenic and carcinogenic efficiencies of indoor pollutants like cigarette smoke (both main stream and side stream), smoke released during burning of mosquito repellents and radiations emitted from our housing materials and consumer goods are noteworthy.
Today, cancer has become the biggest “killer” after heart disease. It is well established that alteration in gene(s) of a normal cell i.e. mutation, is responsible for initiation of cancer thus cancer is genetical in origin and starts from somatic mutation. This is ample evidence that mutations in human somatic calls are indicators of cancer.