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The Price of PCBs

By Tim Frederikson

Any technological development comes with a price-tag of some form or other. Organochlorine compounds, such as polychlorinated biphenyls (PCBs), have a heftier price-tag than most.

From the 209 possible PCB isomers there emerged a synthetic tool hailed as a triumph of technology. PCBs are chemically very stable and their resistance to heat, their high electrical insulation properties and their high dielectric constant made them the natural choice for transformers, capacitors, hydraulic fluids, paints, plastics, pesticides, cutting oils and a myriad other products.

For years PCBs were found every-where until studies began to link the compounds with malignant tumours, still-births and underweight babies. Acute occupational exposures have pro-duced eye inflammations, chloracne and respiratory difficulties.

It was thought that New Zealand would have a smaller exposure to PCBs than the more industrialised nations, because of our smaller scale usage. In fact, the population has a similar level of the chemical in body tissues.

PCBs are virtually non-biodegradable and are heavier than water. They accumulate in body tissues of members of the food chain. If PCBs are disposed of in a manner which allows them to enter a water supply, animals drinking the water or living in it will absorb the chemical and store it in their body fat. If, in turn, those animals are eaten, their accumulated PCBs are added to those already present in the predator's fatty tissue. Move up the food chain and PCBs are found in greater quantity.

In New Zealand we are at the mercy of a number of ocean currents which bring us not only the environmental pollutants of other nations but also a wide range of marine life. It appears that this provides the most common source of PCB contamination for New Zealanders.

In 1984, the Minister of Works & Development instituted a working party to examine and act on the issue. A survey was carried out which estimated that some 177,000 litres of PCBs were held within New Zealand. They have since been banned from importation and withdrawn from the food processing industry. Within the next two years, PCBs are to be totally removed from service.

Strict controls have been put in place to ensure that PCBs do not "escape" into the environment or pose a health risk. New Zealand does not, at present, dispose of its own PCBs or PCB wastes, as we do not have the facilities available for such work. Our PCBs are stored until they can be collected and destroyed by foreign disposal services.

It is important to realise that despite the steps that are being taken, we cannot rid ourselves of PCB contamination in the environment. These compounds are here to stay and they will continue to accumulate in our bodies.

No place is free of PCB contamination. High in in the Andes mountains, lakes now have waters laced by the bodies of PCB-contaminated migratory birds. It's a high price to pay for progress.

Tim Frederikson is a chemical safety consultant.