Sir, - Ronnie Devlin (October 22nd) rightly reminds us that traces of dioxins are produced by many combustion processes and that modern municipal incinerators add only a little to the total. He might also have asked why public campaigns ignore the major sources.
Of course, incineration is not the ideal way to dispose of our wastes. However, it will take many years to develop waste minimisation, composting and recycling to the utopian state of little or no waste. The barriers are not only technical. People will not adjust quickly to the idea that much of what we buy in utopia will cost more precisely because of recycling, (if manufacturers are required to use recycled materials, as seems likely).
In the meantime, the best thing to do with our waste is to landfill much of it (properly!), while working as fast as we can towards better methods. Most developed countries outside the EU are doing this. However, as Nanny EU has placed irrational restrictions on landfilling, we must settle for the next best thing - generating electricity with much of our waste for the decade or two, in well controlled modern incinerators.
Of the uncontrolled dioxin sources, the greatest might well be bonfires, especially where rubber or plastics are burned. Waste-burning in farmyards and on building sites could be major offenders, as could cable-burning by small-scale scrap merchants. For example, the Swiss Environment Agency estimated that the annual national total of dioxin emissions from such sources was twice that from municipal incinerators in 1999. Yet only 2 per cent of Switzerland's municipal waste is illegally burned; most is properly incinerated.
The cumulative emissions of dioxins from rubbish burned on domestic fires and in backyard incinerators could easily be higher in Ireland. With rising charges for waste collection and disposal, these dispersed, uncontrollable and often undetectable emissions could soon become the major source of dioxins.
If the opposition to large-scale incineration forces councils to adopt even more costly methods, the resulting increase in waste charges may tempt more householders to throw most of their rubbish on to the nearest fire.
Thus, municipal waste incineration might cause a small increase in dioxin emissions - but if it prevents an increase in "home incineration", the result could be less dioxins, not more. - Yours, etc.,
Dr Duncan J. Martin, Senior Lecturer in Chemical Engineering, University of Limerick.