W2A-037 Chemical pollution-0.txt
TOWARDS THE AGE OF CLEAN TECHNOLOGY

N. O'Byrne

Increasingly, human-kind is learning that biological life on the planet is a very delicate phenomenon. It thrives only under finely balanced conditions. We call these conditions our 'environment'. It is our responsibility to future generations to prevent any threat to the environment at source.

Today there are about 8 million registered chemicals in the world, and this total is forever increasing. Most, however, exist only in laboratories. Around 70,000 of them however are used daily by industry and individuals. "Technological progress" has created such a multiplicity of chemicals for different purposes that we are in danger of losing control over their known effects. Everyone of these chemicals affects the environment. Few are necessary for life, while others have negative effects on health, animal or plant life, or on climate.

Most of the human-made chemicals do not occur naturally. Unlike natural substances which have a cycle within nature, synthetic substances follow their own rules, i.e. non-biological and toxic. Raw materials and energy are used and refined into products which after use can become persistent and toxic waste. Many new substances are designed to be very stable. They are virtually immune to biological breakdown. They will be in our environment for a long time. Freon is an example which will lead to damage to the ozone layer for the next 100 years. DDT and other PCBs are other examples of environmental toxins that will continue to cause damage for decades. If the invention, production and use of synthetic chemicals is allowed to keep increasing we risk a steady increase in environmental crises, either in the short run, or in the as yet unforeseen longer term. The risks arise from all aspects of the chemical process, i.e production, transport, use and disposal.

It will soon be necessary to seriously consider reducing the flood of chemicals. The traditional approach to dealing with environmental threats posed by chemical processes has been to reduce the environmental load caused by emissions of various kinds. Purification plans or processes are used to take care of the immediately known harmful substances in industrial and household wastes. Often incinerators are used to try to destroy toxins. The problems with this approach is that many of the synthetic substances cannot be destroyed, only redistributed or diluted. Purification processes transfer the chemicals to a sludge which creates a further disposal problem. Incineration creates gases containing new and often even more toxic substances. We may soon be forced to review our approach to dealing with chemicals and the environment, if indeed it is not already too late. Increasing recognition must be given to what is known as the "Precautionary Principle" in dealing with discharges to the environment. This involves an acknowledgement that a substance could cause harm without scientific proof being presently available that it actually does cause harm. Problems often arise because only the short run consequences of large quantities of a chemical are known. For instance, sufficient data to predict human health effects from exposure (one chemical at a time) to the more than 70,000 synthetic chemicals now in production exists for less than 1% of these chemicals. Virtually nothing is known of the effects of chemical mixtures. Accidents are not provided for, except for emergency/disaster mopping-up plans. Long term consequences, however, can emerge where they are least expected. This is a lesson learned from past disasters. Must we always wait until there are enough dead or dying bodies around before taking action? We cannot afford more mistakes, or to wait until real harm has been proved before taking action. Adopting a preventative strategy will open a wide range of opportunities to avoid negative environmental consequences in the future. Such an attitude may make today's environmental threats unnecessary, and perhaps even unprofitable. Such an attitude can serve to prevent environmental problems at source. This is relevant to all industries and should be integral to all development policies. The practicality of this approach can be considered in relation to the following example of Chlorinated Solvents and the Paper Industry.

A'solvent', as the name implies is something that dissolves something else. The most common solvent is ordinary water. Most substances are soluble in water. Many synthetic substances foreign to nature, however, are not soluble in water. To dissolve them, other substances not found in the natural environment are used. Various petroleum based organic solvents are therefore produced with qualities that make them suitable for this purpose. Chlorinated solvents are organic solvents that contain chlorine. Chlorine is classed as a halogen and organic substances containing halogens are called halogenated hydrocarbons. In addition to chlorinated solvents, this group contains environmental toxins such as DDT, Lindane (pesticides), other toxic PCB's (polychlorinated biphenyls) and also dioxins. * Past experience with stable and toxic organic solvents has been an unhappy one for the environment.

Chlorinated solvents are today spread around the world as they are volatile and evaporate easily. Globally, more than 6.14 million metric tonnes of commonly used halogenated solvents are produced and potentially released into the atmosphere each year. A few occur naturally. Methyl chloride can be produced by bacteria in the oceans or as a result of burning vegetation. However, of the total atmospheric content of halogenated hydrocarsons, less than 1% comes from natural sources. Other chlorinated solvents exist entirely within our industrialised society with no natural source.

The amount of chlorinated solvent in the atmosphere is determined by the lifetime of the substance and the rate at which it is added to by emissions. Carbon Tetrachloride, which is very stable, remains in the atmosphere for 76 years. Since it has seen used in large amounts over the past decades, high concentrations have already accumulated. It is currently the most important non-CFC ozone depleter. In 1985 it was responsible for 8% of total ozone depletion. Another common degreaser, Methyl Chloroform, could become a major ozone depleter world-wide in the next few decades unless use is checked now.

Because chlorinated solvents have been used in industry for several decades, the health effects in the working environment are well known. They were initially regarded as relatively harmless with low toxicity. The dangers of skin damage or of long term inhalation are now known, and some unions recognise the need to limit worker exposure. All chlorinated solvents are fat soluble and thus they accumulate in fatty tissues. This enhances the harm they do. Many are now classified as carcinogens. When the solvents eventually breakdown, they can form new substances that are even more toxic than the original chemical. For instance, methyl chloroform forms highly toxic phosgene gas when burnt.

Chlorinated solvents in the atmosphere either eventually breakdown in the troposphere or are transported into the stratosphere. Freons (one of the CFCs) contribute to the thinning of the ozone layer. This arises when the stable freons reach the stratosphere where they are broken down by solar radiation, releasing chlorine atoms. This chlorine is very reactive and quickly breaks down the surrounding ozone. A single chlorine atom can breakdown several hundred ozone molecules. The other chlorinated solvents that reach the stratosphere are broken down in the same way as CFCs and have the same direct effect on the ozone layer.

Chlorinated solvents also contribute to the rise in global temperature i.e.. the 'Greenhouse Effect'. Although carbon dioxide is the most important greenhouse gas, chlorinated hydrocarbons are also important. They absorb a different type of heat radiation, contributing to overall global warning.

When chlorinated solvents breakdown in the atmosphere they contribute to the formation of hydrochloric acid which adds to acidification of rainwater and soil. Hydrochloric acid is ranked as the third most important cause of acidification after sulphur and nitrogen. It has been calculated that present global emissions of chlorinated hydrocarbons yields at least 2 million tons of hydrochloric acid per year. Hydrochloric acid also has the ability to form microscopic drops in the air and this can contribute to the formation of "smog".

The effects of chlorinated solvents are thus well documented. Sooner or later, 100% of the solvents used enters the environment - either in pure form, or as breakdown products, or after reacting with other substances. They affect humans, animals and plants. In order to prevent environmental problems, a complete understanding of how toxins are formed and spread is of critical importance. This would require that the paths of all substances from production, transport, use and disposal be known. This would make it easier to find the sources of toxic contamination, and to take measures to prevent emissions to the environment and to find suitable alternatives.

Increasingly for most uses of chlorinated solvents, there are alternative processes and products that are more acceptable from an ecological viewpoint. Alternatives can be divided into 3 groups - chemical alternatives, process alternatives and system alternatives.

The principle of chemical alternatives is to find chemicals to do the same job, but without the disadvantages of the currently used chemicals. Some chlorinated solvents can be replaced by a natural substance;- water, our most common solvent. The largest industrial use of chlorinated solvents is degreasing. Replacements based on natural substances such as alcohols are available. Among consumer products, white correction fluid, e.g.. "Tipp-Ex" is a good example of a product for which there is an alternative - water for the currently used 1.1.1. trichloroethane. In industry, chlorine based bleaches can be replaced by less harmful hydrogen peroxide.

Replacing a chemical in a process often calls for the process to be adapted. The purpose of the process remains the same. Choosing the right process alternative may sometimes make the use of solvents unnecessary. For paint removal, mechanical grinding or blasting can render harmful chemicals redundant. The use of chlorinated solvents in the dry-cleaning industry could be reduced with redesigned machines using other cleaners where water-soluble cleaners don't do the job. To avoid the use of chlorinated solvents in degreasing, laser techniques can replace metal working processes such as die stamping and machining which gives rise to the need for the use of the chemicals.

System alternatives arise in the case where the purpose of the process or product is questioned. The solution to the environmental problem is to see that the demand for the process ceases. The paper industry is a good example. Increased use of recycled paper is often seen as the aim of environmentalists. This is, however, only one issue in a complex problem.

Increasingly European recycling companies are turning to hydrogen peroxide for bleaching of secondary paper fibre. This has little environmental impact. There is growing acceptance that brilliant white paper is not required for all purposes. This trend is consumer led. As far as the paper industry is concerned it represents only a small step towards clean technology. There will inevitably be growing awareness of the problems associated with the current paper industry processes. This coupled with awareness of the existence of ecologically sound alternatives will lead to a growing demand for "Clean Technology" from the paper industry, i.e., a paper industry that does mot produce dangerous waste. The paper industry is, however, not to be regarded in isolation. The global threat to the environment requires that this concept be applied to all industries Decision makers, internationally, nationally and locally will be responsible to bring this about before it is too late. Public opinion made aware of the issues involved by environmentalists and others will expect it and demand that pollution threats be eliminated at source.

Recycled paper is promoted as it reduces the demand for virgin wood, and the need for vast mono-culture plantations of suitable trees. It can also contribute to the problems of waste disposal by reducing the quantity of waste to be disposed of. There are, however, a number of environmental problems associated with paper production which are overlooked in the recycling debate.
