With the growth of industry, there has been a considerable increase in the discharge of industrial
waste to the environment, chiefly soil and water, which has led to the accumulation of heavy metals,
especially in urban areas. Slow depletion of heavy metals also takes place through leaching, plant uptake,
erosion and deflation. The indiscriminate release of heavy metals into the soil and waters is a major
health concern worldwide, as they cannot be broken down to non-toxic forms and therefore have
long-lasting effects on the ecosystem. Many of them are toxic even at very low concentrations; arsenic,
cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, zinc etc. are not only cytotoxic but
also carcinogenic and mutagenic in nature [1]. Some metals are required by plants in very small amounts
for their growth and optimum performance. However, the increasing concentration of several metals in soil
and waters due to industrial revolution has created an alarming situation for human life and aquatic biota.
This is evident from various reports citing harmful effects of heavy metals on human health (Table 1).