Hazardous Chemicals : Asbestos, Lead and Mercury

Silahkan Bagikan Tulisan-Artikel ini :

ASBESTOS

Asbestos

Asbestos is a naturally occurring mineral that can be processed to form practically indestructible fibers. Peope who work with asbestos are exposed to a significant hazard, since inhaling or ingesting even very small amounts of asbestos is associated with an increased risk of cancer of the lungs and the intestinal tract in susceptible people.

But there is also evidence that relatively small amounts of asbestos fiber pose a threat to the health of the general public. City dwellers breathe in the fibers with the air, and asbestos has also been found in wines filtered with asbestos mesh, in baby powder, and in water supplies. Most of our homes and cars contain some asbestos in insulation, water pipes, brake linings, and the like.

LEAD

Lead

Lead is a naturally occuring element, usually distributed in low concentrations. Since the introduction of the automobile, however, the lead content of the atmosphere has greatly increased, for it has long been an additive in leaded gasoline. Furthermore, until recently lead was used in many paints, automobile batteries, ceramics, glassware, pipes, and other manufactured goods. The basic danger from lead lies in lead poisoning, which causes weakness, loss of appetite, anemia, and damage to the nervous system.

Federal law now requires companies whose products contain lead to use minimal amounts of lead, thus reducing the risks of atmospheric lead poisoning. Of even greater danger is lead poisoning that may occur when children eat lead-based paint and putty, usually off walls and woodwork in older buildings. Hundreds of children have died from this type of poisoning over the years, and thousands of others have suffered chronic symptoms related to it. Studies have found that children whose blood contains elevated levels of lead tend to score lower on intelligence tests than children with normal blood.

MERCURY

Mercury

Mercury is a naturally occuring element that is widely distributed in the earth`s crust. In its elemental form, mercury is a very stable metal, and mercury salt are considered quite insoluble. However, certain microorganisms can convert elemental mercury and other forms of mercury into an organic form, methyl mercury, which, when consumed in large enough quantities, produces devastating symptoms.

Unfortunately, this fact was not discovered until several years after a tragic incident. From the early 1930s until 1971, certain Japanese factories released industrial wastes containing substantial quantities of mercury into the Pacific Ocean. Marine microorganisms metamolized the mercury to its organic form, which became progressively more concentrated as it passed along the food chain to higher organisms. The highest organisms in the chain were human beings-residents of a fishing village on Minamata Bay, whose diet consisted almost solely of fish. The high level of mercury in the fish they ate resulted in fifty-two deaths; more than a hundred other people experienced serious symptoms, including inability to speak, mental retardation, numbness of arms and legs followed by deterioration of muscle tissue, gradual loss of vision and hearing, disruption of equilibrium, loss of coordination, and emotional disturbance. Many of these victims are now permanently disabled, and children born to mothers who consumed the contaminated seafood are severely deformed.

As a result of the Minamata episode and other mercury-related disasters, most industrialized nations have instituted strict regulations prohibiting mercury pollution, and acute mercury poisoning from contaminated food is now far less likely than it was a decade ago.

References :

J.E. Fielding and P.K. Russo, “Exposure to Lead: Sources and Effects”, New England Journal of Medicine 297, No. 17, 1977.

Marvin R Levy, Mark Dignan, Janet H Shirreffs, Essentials of Life & Health, Fourth Edition, Random House, New York, 1984.

Artikel Lainnya:

Silahkan Bagikan Tulisan-Artikel ini :