Organochlorines

Organochlorines are a large class of chemicals including industrial organics, agricultural organics, by-products of anthropogenic activities, and chemical transformation products. They are important environmental contaminants due to their high stability and persistence in the environment, high big-accumulation potential, potential for high chronic toxicity, and as a result of the large quantities which have been released into the environment. Source: Department of Indian Affairs and Northern Development

·  Polychlorinated biphenyls (PCBs) · Hexachlorobenzenes (HCBs) · Hexachlorocyclohexane (HCH) · DDT · DDE · Mirex

· Chlordane · Toxaphene · Endrin · Aldrin · Dieldrin · Lindane · Dioxins · Furans

1 ) Industrial Organics Sources: incineration volatilization

PCBs (polychlorinated biphenyls)

• human symptoms include diseases of blood, immune and nervous systems, respiratory impairment, dermal toxicity, and mutagenic and carcinogenic effects
• Iinked to premature births, reduced birth weight, smaller head circumference, compromised neuromuscular development

• porphyria, still births in humans
• developmental abnormalities in rats

 HCH (hexachlorocyclohexane)

• banned in 28 countries and severely restricted in five
• spread via evaporation and air transport
• repeated exposure linked to damage of kidneys, pancreas, and nasal mucous membranes
• accumulates in breast milk and fatty tissues

• banned in eight countries and severely restricted in five
• affects central nervous system
• Iiver and kidney damage in test animals
• probable carcinogen
• Iinked to aplastic anemia
• harmful to developing embryos in test animals

• causes numbness, parathesia, weakness or paralysis
• carcinogenic

• causes egg shell thinning in avian species
• reduces egg viability in fish

• Iinked to cancer in laboratory animals

• carcinogenic
• extreme toxicity in fish populations (used as piscicide)

• banned in 38 countries and severely restricted in 12
• classified as ``acutely toxic" by World Health Organization
• has caused cancer in test animals
• prolonged exposure can lead to severe convulsions and, in some cases, death

Aldrin

• banned in 34 countries and severely restricted in 13
• probable carcinogen
• extremely persistent, bioaccumulative
• breaks down to dieldrin in living systems
• believed toxic to fish, freshwater invertebrates, and birds

• used in herbicides and defoliants
• found in foods associated with cotton-seed byproducts
• Iinked to weight loss, hair loss, skin lesions, and cancer

• appears as a contaminant in use of zinc
• causes severe gastroenteritis (linked to itai-itai disease in Japan)
• associated with chronic lesions, testicular necrosis, fetal malformation, cardiovascular hypertension

• suspected carcinogen

3) Anthropogenic By-Products

Dioxins/Furans

• possible carcinogens, though still under study believed toxic to fish

Dieldrin

• banned in 34 countries and severely restricted in 21
• used for control of termites, desert locusts, mosquitos, and tsetse flies in developing countries
• extremely carcinogenic
• linked to liver cancer, muscle spasms, tremors, developmental abnormalities
• concentrates in breast milk

• originates from lead smelters, solder, gasoline
• attacks nervous system
• Iinked to diseases of kidney and haematopoietic system
• may lead to acute encephalopathy, anemia, nephrosis

• organic mercury, particularly methylmercury, highly toxic
• causes severe gastroenteritis, nephritis
• affects brain, causing serious and irreversible damage
• common in aquatic systems

 Heavy metals are metals of high specific gravity. Metals are required for the life processes of animals, including man. The body requires substantial amounts of some metals (for example, sodium and iron) and has a high tolerance for their absorption. Other metals, such as the "micro-nutrients" copper and zinc, are required in much smaller amounts, and the body has a lower tolerance. Finally, there are metals which are not essential to life processes and are toxic to both man and other species at lower levels.

 The effects of such substances vary with the metal. In some cases, heavy metals attack nervous tissues by enzymatic blocking of biochemical reactions. More frequently, they destroy excretory organs, such as the liver and kidneys.

· Beryllium · Mercury · Thallium · Boron · Nickel · Titanium

· Cadmium · Selenium · Vanadium · Lead · Zinc