Although zinc is classified as a heavy metal, it is essential for
human, animals and plants. Its deficiency has adverse effects on
human growth, immunity, reproduction and cognity. But excess
amounts of zinc should also be avoided as it causes pollution. Excess
zinc oxide may be released as a result of abrasion of rubber
goods and during their production and leaching into the rain water.
Zinc has toxic effect on specially algae rather than other microorganisms.
Therefore release of zinc to the environment should be
controlled and thus zinc oxide content in tires and rubber goods
should be kept as low as possible for environmental and economic
reasons [2–5]. Besides these concerns, the formation of excess zinc
sulfide during vulcanization which is deposited inside the surface
of the mold as a residue is to be removed and this affects productivity
adversely [6].