Environmental Risks Associated with Heavy Metal Contamination in Soil, Water and Plants in Urban and Periurban Agriculture

Abstract

The India's population living in cities and urban areas has doubled to 27.8% since Independence. Our cities face enormous challenges of environmental pollution and health related problems. City authorities have often been reluctant to accept urban and periurban agriculture because of perceived health risks. Nevertheless, in most cities the world over, periurban agriculture is practiced on a substantial scale, despite prohibitive laws and regulations. Non-degradable pollutants added to the system through anthropogenic activities like heavy metals in air, soil, water and crops bother us more than others as these tend to bio-accumulate. Throughout history, heavy metal contamination has long plagued mankind - undermining intelligence and causing debasing behaviour. Toxicity of some of the heavy metals even leads to deficiency of essential metals like Zn, Cu, etc. in both human and animals. Climate, nutritional status, genetic predisposition, type of work and exposure level influence the intensity of impact on health. Permissible levels prescribed by different organizations differ because of differences in tolerance levels of people of different origins and differences in threat perception of the people. With our current level of knowledge a permanent and foolproof method to stop entry of heavy metals into the food chain is impossible. However, methods are available to reduce intensity of the effects. Alternative land use with crops not directly consumed by human beings and animals offers a better remedy to contain heavy metal entry into food chain. India has a wide ranging set of environmental laws that lay down norms for air, water, soil, wastes, etc. Legislative frame work has been developed in the belief that a policing model is sufficient. It does not go beyond that. Regulatory mechanisms may not be effective in isolated cases but are essential drivers to augment other approaches, by putting a "cap" on the level of degradation that is socially acceptable, as well as creating space for other, cleaner and more acceptable alternatives to be "viable".