PCB-iron

[[image:http://pirun.ku.ac.th/%7Efscinpc/public_html/image/scientist_430.jpg]]
===Hello, my name is Robert Tokar and I am here with my partner Alexis Montgomery. We are sophomores at Science Leadership Academy. Today, we would like to spend some time talking to you about Polychlorinated biphenyl, or PCB for short. PCB's can be found in countries all around the world. They are mainly used to sustain all difficult degradation mechanisms. It is an organic compound that serves many purposes and is used for a variety of industrial resources, such as: coolants, lubricants, stabilizing additives in flexible PVC coatings of electrical wiring and electronic components, pesticide extenders, cutting oils, hydraulic fluids, sealants, adhesives, wood floor finishes, paints, de-dusting agents, and in carbonless copy paper as well.===

==="Polychlorinated Biphenyls make up a group of 209 individual chlorinated biphenyl rings known as congeners. They were typically manufactured as mixtures of 60 to 90 different congeners. In the concentrated form, PCBs are either oily liquids or solids with no discernable taste or odor. As the number of chlorines in a PCB mixture increases the flash point rises and the substance becomes less combustible. Also, PCBs with large numbers of chlorines are more stable and thus resistant to biodegradation. The most highly favored PCBs tended to be the ones with large numbers of chlorines. These congeners are also proving to be the ones that present the greatest environmental and health risks."===

==="First manufactured by Monsanto (the only American company to manufacture PCBs) in 1929, PCB's were quickly acclaimed as an industrial breakthrough. These chlorinated oils have a low degree of reactivity. They are not flammable, have high electrical resistance, good insulating properties and are very stable even when exposed to heat and pressure. All in all, they seemed to be the perfect oil for use in dielectric fluids, and as insulators for transformers and capacitors. Not only were PCBs hailed for their role in preventing fires and explosions, they were actually required by fire code. Uses for PCBs quickly expanded to include hydraulic fluids, casting wax, carbonless carbon paper, compressors, heat transfer systems, plasticizers, pigments, adhesives, liquid cooled electric motors, fluorescent light ballasts, etc."===

In 1973, the use of PCBs were banned in dissipative sources, such as:
===However, they continued to be allowed in "totally enclosed uses" such as transformers and capacitors, which, in certain failure modes or out-of-specification conditions, can leak, catch fire, or explode.===
 * ===Plasticizers in paints and cements===
 * ===Casting agents===
 * ===Fire retardant fabric treatments and heat stabilizing additives for PVC electrical insulation===
 * ===Adhesives===
 * ===Paints and water-proofing===
 * ===Railway sleepers===

===PCB's do not degrade readily. Though many different forms are used to destroy it, it is extremely difficult to get rid of it completely. The process is very slow, and so a long period of time is needed to accomplish this task. The three methods used to destroy PCB's include physical, microbial, and chemical destructions.===

===The most commonly observed health effects in people exposed to extremely high levels of PCBs are skin conditions such as chloracne and rashes. Studies in workers exposed to PCBs have shown changes in blood and urine that may indicate liver damage.===

===Since its prohibition back in the seventies, companies have spent millions of dollars trying to put PCB's back into the market. What's worse is that they are funding research facilities that make scientists show the public that PCB's are in fact unharmful and that their toxicity levels can be controlled. Personally, I think that the government needs to step in and put a stop to it. If greedy businessmen and cheap gas engineers continue to try and permit PCB's back into society, then injustice and cruelty will be to blame. Certainly the healthcare system would benefit from the soon-to-be increase of ill citizens, but why put so many innocent lives at stake? It's not worth the trouble. These big companies should start putting their financial resources elsewhere; possibly trying to find other ways to get the same result, but with safer and more reliable alternatives.===