Fullscreen HTML5Med Res (??MB)HTML4

What you need to know about polychlorinated biphenyls (PCBs) Up till now, whenever you've thought of PCBs, you've probably thought of printed circuit boards. But there is another more sinister meaning for PCBs - polychlorinated biphenyls. These are ·a type of oil which was widely used in the electronics and electrical industry about 15 years ago. By MARQUE CROZMAN Where can you expect to find PCBs? The answer is virtually everywhere. PCBs were used as the impregnating oil in huge numbers of AC capacitors up until about 1975. And where will you find these cantype AC capacitors? Most frequently in fluorescent light fittings but also in ceiling fans, dishwashers and in fact in any electrical appliances which used capacitor splitphase motors. The capacitors we are talking about generally have a value between 2µF and 16µF and are rated at 250V AC or 440V AC. They are housed in aluminium cans which may be flattened or cylindrical in shape, as shown in the photos in this article. The problem is that these capacitors all eventually leak. They may start to leak gradually, or they may fail catastrophically, spraying their hot contents over anyone in the room. When that happens, and it can happen at any time, you have big problems. There are tens of thousands of old buildings around Australia, many with a thousand or more fluorescent light fittings. This means that there are literally millions of PCB-filled capacitors waiting to leak, or spray their contents over people. Power factor correction The capacitors are installed in 4 SILICON CHIP fluorescent light fittings to correct their power factor. In simple language, a fluorescent light is largely an inductive load. The current in such a load "lags" the voltage and this causes losses in the power generation system, in transformers and in transmission lines. The cure is to connect a capacitor of a particular value in parallel with the light. Hence, all fluorescent lights in POISON commercial and public buildings, in factories, schools, supermarkets, workshops and so on have power factor correction capacitors in them. And if these capacitors were made before 1978 they are bound to contain PCB oils. In homes, the situation is a little different. Generally, domestic fluorescent lights do not contain power factor correction capacitors. However, in older homes built before the 1960's, it is not uncommon for fluorescent lights to contain one of these capacitors. Generally these fluorescent lights will be in the kitchen or bathroom - the worst possible place for them to be if they start leaking or spraying their contents everywhere. In garages, the fluoroscent light fittings are often of commercial origin and will also have a capacitor in them. In Australia, these capacitors were made by the Ducan Condenser Company Pty Ltd and the United Capacitor Company [UCC). The origin of PCBs PCBs (also known as "askarels" - see table elsewhere in this article) are a group of insulating oils that are clear to yellow in colour and have a fruity odour. They are excellent dielectrics [ie, ideal for use in capacitors) and are fire resistant. They have been used in the electrical industry since the early 1930s, for two reasons: • PCBs do not burn or sustain combustion under conditions of internal electrical arcing of transformers. • Power capacitors filled with PCBs are significantly smaller, more reliable, more durable and safer than earlier capacitors filled with mineral oil. It is precisely because PCBs are such stable compounds that they are a problem when they get out into the environment. You've heard of DDT and its problems. Now there is the PCB story. Early warnings In 1966, traces of PCBs were found in the environment. Further research showed that the contamination was due to the highly chlorinated isomers of the PCBs. These components are highly resis- ELECTRONICS WORLD SPECIALS FOR THIS MONTH 240V AC Variable Temperature Soldering Iron. Was $44.95 NOW $35.00 Soldering Iron Stand Was $13.95 NOW $9.95 Solder 250g Roll Was $5.50 Any capacitor of several microfarads and rated at 250V AC or 440V AC, in an aluminium can, is likely to contain polychlorinated biphenyls. Because they are such stable and long-lived compounds, PCBs can pollute the environment for hundreds of years. tant to biodegradation and are toxic. After further tests, in 1973 it was decided to restrict PCBs to uses in electrical transformers and high voltage capacitors. In 1976, Australia banned the import of PCBs and proposed the phasing out of PCB products in use as replacements became available. So why are we still talking about PCBs? Because virtually all the PCBs ever made are still in use and if not reclaimed, will eventually contaminate the environment. Once they are in the soil, PCBs are extremely persistent. They can build up in the food chain and ultimately pose a risk to most living organisms. Early history PCBs were first used in power capacitors and then in power transformers. The first description of PCBs was published by Schmidt and Schultz, in 1881. PCBs were first commercially produced in 1929 as a fire-resistant dielectric for capacitors by the Swann Chemical Company. The company was later bought out by Monsanto Chemical. Dr Frank Clark patented its application for use as a transformer insulating fluid for the General Electric Company in 1931. The first transformers were put into service in 1933. During the 1930s and 1940s, a number of mining accidents had occured because of the poor insulation of cables. These accidents decreased dramatically after the introduction of PCBinsulated cables. The US Underwriter's Laboratory stated: "Transformer askarels are considered non-flammable at ordinary temperatures. Under practical conditions, formation of combustible or explosive mixtures is regarded extremely unlikely. The fire hazard is very small". These unique fire resistant capabilities led to PCBs being used in many other applications such as: AC capacitors, hydraulic fluids, lubricants, paint pigments, sealants, adhesives, printing inks, and even floor waxes. Over a million tonnes of PCB were produced between 1931 and 1977. Virtually all PCBs in ex- NOW $4.50 Universal Tool - Crimper, Stripper, Bolt CutterPliers, ONLY $6.50 Beginners Multimeter 15 Ranges Was $24.95 NOW $19.95 Self-Resetting SA Bi-metal Cutout. Ideal for Battery charger, Power Supply etc. ONLY 75c Business/Home Answering Machine $129.00 Mail Orders Welcome 30 Lacey St, Croydon VIC, 3136. Telephone: (03) 723 3860 (03) 723 3094 Fax: (03) 725 9443 ► .,_ ____________,. OCTOBER 1990 5 TABLE 1: TRADE NAMES OF PCBs Apirolio {Italy) Aroclor {UK, USA) Asbestol {USA) Cloresil Clorextol {USA) Clorinol Clorphen {Germany) Diaclor Diconal DK Duconol (Australia) Dykanal Elemex Educarel Hydrol lnerteen (USA) istence today were produced synthetically. Risks of PCBs There has been considerable evidence gathered as to the effects of PCBs on man and animals. In 1968, several thousand workers in Yusho, Japan, ate food that had been cooked in rice oil contaminated by PCBs. They suffered nausea, lethargy, skin rashes, eye discharges, jaundice and other effects. The maximum dose of PCB thought to have been eaten was about 2 grams. Eventually, some 1200 people were examined, although several thousand were thought to have been affected. The symptoms persisted for several years although there were no deaths directly at- Kanechlor (Japan) No-Flamol (USA) Pyralene {France) Pyrochlor {UK) Saf-T-Kuhl (USA) Solvol (USSR) Therminol tributable to this incident. Several authorities now believe that the real culprit in this Yusho incident was not "normal" PCB at all, but one by-product of the heating of PCBs (320°C): polychlorinated dibenzofurans, which may be 500 times more toxic than PCBs. This by-product, caused by the cooking of the oil, was the poison. Animal tests have indicated that PCBs are associated with liver hepatomas and benign and malignant melanomas in mice and rats. It is now suspected that PCBs are a human carcinogen (ie, they cause cancer). PCBs are also suspected of causing damage to the human reproductive system. This effect is similar to the effect of DDT on the reproductive system. Early tests on PCBs showed that they resembled DDT in · many aspects, the main difference between the two being their onset of toxicity. The toxic effects of DDT appear within hours, whereas the effects of PCBs accumulate over time, and this poses an even greater health risk. The persistence of DDT in the soil is about one year, whereas it is believed that the persistence of PCBs in the soil may be hundreds of years. PCBs can be absorbed through the skin, or simply breathed in as a vapour. They can cause: liver damage; neurological disorders such as headaches, depression and dizziness; damage to the nervous system (eg, weakness, numbness and tingling in the arms and legs}; and "chloracne", a skin condition resembling chronic acne. In 1933, a few years after the beginning of large scale PCB production, 23 out of 24 workers developed chloracne following exposure in a PCB manufacturing plant for about 6 months. Over the years since, many other cases of PCB associated chloracne occurred. Chloracne may occur in nearly every worker exposed to PCBs, if the exposure is high enough. Since the effects of PCBs only become evident through high exposure or high levels of accumulated exposure (bioaccumulation}, we are only now beginning to find out what are the long term effects of lower doses of PCBs on humans. These may not show up until years afterwards. What to do about PCBs Have look around your own home for PCB capacitors. You may be ~urprised at what you find. The capacitor on the left came from a 12-year old dishwasher while the larger one on the right came from a vacuum motor in an old computer tape drive. 6 SILICON CHIP OK, PCBs are nasty compounds. So what do you do if you suspect that one of your fluorescent lights or appliances has an AC capacitor in it which was made before 1978? Having looked at some of the capacitors shown in this article, it is quite easy to identify suspect capacitors. What if they are leaking? If they are leaking, the capacitors should be removed immediately. If they are left there, they may well . fail catastrophically. If the capacitor is associated with an electric motor in an appliance, it must be replaced with a capacitor of equivalent value and rating. In domestic fluorescent lights, power factor correction capacitors can generally be removed and not replaced (if you don't know how to do this, call an electrician). Fluorescent light fittings in commercial or public buildings must have power correction capacitors. In buildings erected before 1980, the fluorescent light fittings are almost certain to contain PCBs. If any of these are found to be leaking, they should all be replaced as a matter of urgency. It is not sufficient to merely replace those that are leaking. Incidentally, unless the fluorescent light fitting is partly dismantled to examine the power factor correction capacitor, it is not possible to know whether it has been leaking or not. That may seem obvious, but the point needs to be made. In the long term, all capacitors containing PCBs should be removed and replaced. If PCB oil does come into contact with your eyes, nose or mouth, flush the area thoroughly with water and seek medical advice, as soon as possible. If PCB oil spills onto your clothing, you should change your clothing and shower thoroughly, as soon as possible. Contaminated clothing should either be disposed of or laundered by people who have been informed of the hazards of PCBs and are familiar with handling procedures. Do not eat, drink or smoke in an area where PCBs have been spilt or are being handled. Cleaning up a spill To avoid contact with the skin, protective clothing should be worn. These should include disposable overalls, protective gloves, eye protection and footwear. These materials should be disposed of with the PCB waste when finished. In Safety measures If you come across a capacitor which is leaking, do not touch it. At the very least, you must wear rubber gloves. If you do come in contact with the liquid, wash your hands thoroughly as soon as possible. Make sure you do not touch your mouth, nose or eyes or severe irritation may result. POISON Made by Ducon Condenser Pty Ltd, this 6.5µ,F 250VAC power factor capacitor is typical of those in millions of fluorescent light fittings in public and commercial buildings around Australia. They all should be removed and replaced with non-PCB capacitors. limited access areas, adequate ventilation should be provided. A respirator with organic cartridges should be used in confined areas. Should any PCB material be consumed, medical advice should be obtained. Disposal Disposing of PCBs is not a simple matter. The PCB material needs to either be destroyed, converted to safe end products, or totally removed from the environment. The following have been put forward as possible solutions for PCB disposal: • high temperature combustion in incinerators, high efficiency boilers and cement kilns; • radiant energy; • chemical dechlorination; • biological degradation; and • landfill or subterranean deposition. None of these disposal methods are available in Australia at present. Great. Nor are there any real plans or policies for disposal of large numbers of capacitors conOCTOBER 1990 7 ® POISON What you need to know about polychlorinated biphenyls ... Homes more than 30 years old often have fluorescent light fittings with dodgy capacitors. The older they are, the more likely they are to leak. This fitting was one of several in the ceiling of a 40-year old house. Exercise due caution when removing PCB capacitors from light fittings. taining PCBs in Australia. Great again. Currently, high temperature incineration is the most cost effective way of totally destroying PCBs. Two companies in Australia have contracts to ship our toxic wa.stes to Europe for incineration. Capacitors may be stored in sealed 205 litre drums and sent to these two companies for storage and eventual despatch overseas for incineration. The two companies in question are: • AACI, 10 Bridge St, Granville, NSW 2142. Phone 02 682 1660; and • Jancassco Pty Ltd, Ordish Rd & Cahill St, Dandenong, Vic 3175. Phone 03 794 9633 . OK, so what do you do when you have one or a few capacitors containing PCBs. Legally, you may dispose of these with your household garbage. Eventually, that means that lots and lots of PCB filled capacitors are going to end up in municipal garbage tips around Australia. Or worse, they may be burnt in municipal incinerators. We are not happy about this. Nor should you be. 8 SILICON CHIP In our opinion, you should contact your local council and ask them where these capacitors are to be collected and stored. If your council does not know (or worse, tells you to stick it in the garbage), they should contact the NSW State Pollution Control Commission, the NSW Metropolitan Waste Disposal Authority (or the equivalent bodies in your state), or the Electricity Supply Association of Australia. By rights, all capacitors containing PCBs should be safely stored for ultimate disposal by high temperature incineration. If you are involved with large scale replacement of capacitors High temperature incineration is the most cost effective way of destroying PCBs containing PCBs in commercial or public buildings, you should contact the above bodies before proceeding. Bibilography (1). The Properties of Askerels & Recommendations For Their Use in Electrical Equipment - Electricity Supply Association of Australia. D(b)32-1984. (2). Assessment of Polychlorinated Biphenyl (PCB) Wastes, by Anthony J Farrugia. 88/1. ISBN O 7305 0774 2. State Pollution Control Commission. (3). Report of An Inquiry Into the Potential Health Hazards of Polychlorinated Biphenyl Compounds in New South Wales Schools Department of Education, (24/11/ 89). (4). Encyclopaedia of Occupational Health & Safety (Third Edition) International Labour Office, Geneva. (5). Spot the PCB - NEWSWIT (December, 1989), University of Technology, Sydney. Acknowledgement Special thanks to Bill Holliday (University of Technology, Sydney) and to Leo Pomery (NSW Teachers Federation) for their assistance in the preparation of this article. ~