Defining Polychlorinated biphenyl
A group of chemicals used in variety of consumer products including dyes, plastic, paint, rubber and consumer electronic are called PCBs or polychlorinated biphenyl. Aroclor and Pyranol are the commercial Brand names of PCB mixture. Though the Congress banned PCBs in 1976, they are present in the environment even today because they do not break down naturally or on their own.
Human beings risk exposure from PCBs by meat, fish, drinking water and dairy products. The use of florescent lights and capacitors made before 1977 increases the risk of PCB exposure at home. The Environmental Protection Agency classifies PCB as a carcinogen. The harmful effects of PCB exposure includes immune deficiency, birth defects, skin rashes and impaired neurological development.
The mixture of up to 209 individual chlorinated compounds forms Polychlorinated biphenyl. Neither there are natural sources of PCBs nor they are produced in the United States but they are still present in environment. They are colorless and light, solid and oily liquids .They have no smell and taste. PCBs are good insulators and do not burn easily. Thus they are used as lubricants and coolants in electrical equipments , transformers and capacitors.
PCBs Effect on Environment
PCB enters environment through accidental spills and leakage, from leaks in products containing PCBs and enters water, soil and air during their disposal, manufacture and use. PCBs can also be released from hazardous waste sites or improper disposal of consumer products and other wastes , from the waste burning in incinerators and from the leakage of old electrical transformers. As they do not breakdown in the environment naturally, they are found in the environment for long time.
People using old fluorescent lighting fixtures electrical devices and appliances such as refrigerators and television sets, that were made 30 years ago are exposed to PCB. These devices or appliances leaks small amount of PCB when they get hot during their usage. Fish , dairy products and meat are dietary sources of PCBs. Occupational exposure occurs through maintenance and repair of PCB transformers.
Affect of PCB on Health
The PCB exposure causes immunological changes in children and acne like skin condition in adults. It causes cancer in animals. People exposed to large amount of PCB may suffer from skin problem like rashes and acne. According to the studies conducted on workers exposed to PCB showed changes in blood and urine indicating liver damage.
The study conducted on animals fed with large amount of PCB for short period led to the liver damage and in some cases, they even died. On the other hand, animals that were fed with small amount of PCB for longer period developed various health problems like thyroid gland, liver and stomach injuries. PCBs do not cause birth defects.
PCBs and Cancer
According to certain studies, PCB causes cancer of liver and biliary tract. Rats fed with high levels of PCB contaminated food developed liver cancer. The Department of Heath and Human Services anticipated PCBs as carcinogens.
Though there are tests to measure PCB in body fat, breast milk and blood but they are not routinely conducted. As most of the people are exposed to PCBs in the environment , it is found in everybody.
Recommendations by Federal Government
The limit of PCB per liter of drinking water is 0.0005 milligrams. The release of one or more pound of PCB must be immediately reported to EPA . According to the limitations set by Food and Drug Administration , eggs , milk , infant food , poultry , red meat fish and shellfish should not contain more than 0.2-3 parts of PCBs per million.