HazardousChemicals - Case study

Minamata—An important lesson about mercury
A case of human mercury poisoning which occurred about forty years ago in the Minamata Bay in Japan taught the world an important lesson about the dangers of mercury poisoning. A large plastics plant located near the Minamata bay used a mercury containing compound in a reaction to produce vinyl chloride, a common plastic material. The left-over mercury was dumped into the Bay along with other wastes from the plant. Though the mercury was in its less toxic inorganic state when dumped, the microorganisms at the bottom of the bay converted the mercury into its organic form. This organic mercury then entered into the tissues of fish which, were in, turn consumed by the people living in the area. The contaminated fish thus caused an outbreak of poisoning killing and affecting several people. Mothers who had eaten the contaminated fish gave birth to infants who showed signs of mercury poisoning. Mercury poisoning is thus called 'Minamata Disease'.
Thousands of chemicals are used in industries everyday. When used incorrectly or inappropriately they can become health hazards. PCBs (Polychlorinated biphenyls) are resistant to fire and do not conduct electricity very well, which makes them excellent materials for several industrial purposes. Rainwater can wash PCBs out of disposal areas in dumps and landfills thus contaminating the water. PCBs do not break down very rapidly in the environment and thus retain their toxic characteristics. They cause long-term exposure problems to both humans and wildlife. PCBs are concentrated in the kidneys and liver and cause damage; they cause reproductive failure in birds and mammals.

The Bhopal Gas Tragedy
The careless siting of industry and relatively poor regulatory controls leads to ill-health in the urban centers. The Bhopal gas tragedy on December 2nd, 1984, where Union Carbide's plant leaked 43 tons of methyl isocyanate and other substances, used in the manufacture of pesticides, is one of the worst industrial accidents in the recent past. Of the 520,000 people who were exposed to the gas, 8,000 died during the first week and another 8,000 later. The impact on the survivors is visible even today.

Arsenic poisoning—Bangladesh
More than half the population of Bangladesh is threatened by high levels of arsenic found in drinking water. This could eventually lead to an epidemic of cancers and other fatal diseases.
Rezaul Morol, a young Bangladeshi man, nearly died from arsenic poisoning caused by drinking arsenic-laden well-water for several years. The doctor advised Rezaul to stop drinking contaminated water and eat more protein-rich food, such as fish. Since then, Rezaul feels a lot better and is happy that his skin is healing.