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The acute toxicity of PCB is relatively low in an LD50 of 4 g per kg of body weight. Therefore few concerns were originally raised about the possible effects of PCB's on human health. Public and scientific awareness was aroused by a number of incidents, the most serious being the contamination of rice oil in Japan in 1968 which affected over 1500 people.
After consuming grossly contaminated food over a period of months, the victims suffered symptoms including chloracne (a severe skin disease), increased eye discharge, systemic gastrointestinal symptoms with jaundice, oedema, and abdominal pain. Some affected people showed evidence of chloracne three years after exposure.
More recently, studies have given an indication that PCB's may cause cancer in some animals, but the available data from laboratory studies are not adequate to confirm or negate this suspicion. The significance of this to human health is uncertain.
The most common route for people to be exposed to PCB's is through low level contamination of the food chain because of the presence of PCB's in the environment.
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The exposure to PCB's at work represents a greater hazard than usual environmental exposures owing to the possibility of contact with the concentrated liquid. The main risk to humans is from repeated exposures which may result in skin disorders involving a brownish discolouration and a specific skin condition called chloracne.
There are few cases of adverse effects from occupational exposures. Some studies have shown minor reversible changes in liver function in exposed workers but generally effects appear to be limited to burning of the eyes, face and skin when excessive exposure occurs.
Pure PCB's have very low but detectable vapour pressures, so only small amounts of PCB fume are released from exposed PCB liquid. However, PCB's used in transformers are usually a mixture of PCB's and trichlorobenzene (TCB). TCB is a low toxicity organic solvent with a relatively low vapour pressure, such that dangerous concentrations are unlikely to be generated at room temperature.
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FIRST AID
Contact with clothes
Remove contaminated clothing promptly.
Contact with skin
Wipe off any splashes. Wash thoroughly with soap or detergent and water or a waterless cleaner. Apply cold cream (skin lotion) to reduce the irritation, particularly if PCBs have contacted open cuts or abrasions. See a medical practitioner.
Contact with eye
Irrigate immediately with gentle stream of lukewarm water for 15 minutes keeping the eyelids apart while flushing. See a medical practitioner immediately.
Ingestion
Do not cause vomiting. Do NOT drink anything. Thoroughly rinse mouth with water. Proceed to a hospital emergency department or a medical practitioner immediately. Take information on the PCB, both brand name and PCB content if known, with the patient
Inhalation
Get fresh air and see a medical practitioner.
NOTE: Any person developing skin irritation or a respiratory tract irritation should be placed under the supervision of a medical practitioner.
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PROTECTIVE CLOTHING
Where workers may come in direct contact with PCB liquids (greater than 500 ppm PCBs), protective clothing impervious to PCBs should be worn. The proper clothing and gear will vary with the circumstances such as quantity and concentration of PCBs.
If the PCBs are in closed containers such as capacitors, transformers or drums, and THERE IS NO DIRECT CONTACT, special clothing is not needed. Nevertheless gloves should be worn as a precaution.
Protective gear and clothing should be available in all areas where there are significant amounts of PCB liquids, whether in service, in store, or while being transported.
Protective clothing consists of gloves, gumboots or overshoes, Tyvec overalls and bib-type aprons which cover the boot tops. Safety glasses with side shields, chemical safety goggles, or face shields should also be worn.
Impervious gloves made of butyl rubber, neoprene, nitrite rubber, polyvinyl alcohol, viton saranex or teflon (NOT ordinary rubber) should be worn when handling PCB liquids. A respiratory protection device with a full face mask and a cartridge or canister suitable for use with PCBs is required when handling PCBs liquids hotter than 55C, where there is a significant amount of PCB liquid exposed to the air, or where adequate ventilation is not possible. In a fire situation involving PCBs self-contained breathing apparatus should be used.
Any reusable protective equipment should be thoroughly cleaned after use with paper tissues and soapy water. No attempt should be made to wash PCB contaminated clothing for reuse. If available, lightweight disposable clothing should be used and then stored with other solid PCB waste for safe disposal.
Hands should be washed thoroughly with warm water and soap, detergent or industrial hand cleansers before eating, drinking, smoking or using toilet facilities. As people may need copious amounts of drinks while working in protective clothing, plenty of cartoned fruit juices and other beverages which can be drunk with straws should be supplied. |
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