Conclusions
Authors: Fischli Albert E. 
Published: October 2007

A crusade is ongoing against element 17 in the periodic table, i.e. chlorine, one of the most abundant on earth. It is blamed, amongst other things, to be responsible for the depletion of the ozone layer, bioaccumulation of chlorinated compounds such as DDT or PCB's in animals and for the formation of dioxins in urban waste incineration.

Due to socio-economic implications the issue has gone too early beyond the borders of the scientific community, before facts have been proven and evaluated. As a result, it has been treated in inappropriate and emotional ways even affecting scientific ethics in some cases.

Therefore, the International Union of Pureand Applied Chemistry (IUPAC), conscious of its responsibilities in thisarea, has decided to publish this White Book with the collaboration ofoutstanding worldwide renowned scientific specialists from North-America,Europe and Japan in order to inform the public and the decision makersas well as the scientific community in an objective, open and unbiasedway on the up-to-date scientific knowledge.

In doing so IUPAC is following its philosophyto make independent judgments on important issues that are touchy or sensitiveto the general public, governments and industry. IUPAC is not acting asa judge, but would like to critically evaluate the various factors forand against a particular issue.

The occurrence of chlorine in nature andalso in living organisms, either as inorganic compounds or as numerousand very diversified natural "organo-chlorines" does not makeany doubt any more (T. GRAEDEL and W.C. KEENE, G.W. GRIBBLE).

The availability of the raw material, salt,the development of convenient production technologies and the chemicalproperties of chlorine have generated a blooming tree of applicationsin such different fields as the pulp and paper industry (K. SOLOMON),the disinfection of water (H. GALAL-GORCHEV) but mainly in organic synthesisleading to a host of useful products, for example, polymers, pharmaceuticals,pesticides, dyes and pigments (J. FAUVARQUE).

It is quite clear that chemists have notalways been aware beforehand of all the possible consequences of havingmanufactured new molecules, be they chlorinated or not. Chemicals emittedvoluntarily or inadvertently in the environment are distributed thereaccording to a complex set of physico-chemical properties (J. MIYAMOTO, K. BALLSCHMITER).

Volatile compounds such as aliphatic chlorinatedand chlorofluorinated hydrocarbons find their way to the "atmosphericcompartments". Long-lived members of this family are even able toreach the stratosphere where they have been shown to produce detrimentaleffects to the global environment (M. MOLINA).

The substitution of these so-called CFC'sby new shorter-lived molecules has probably been the best example of asound scientific approach to solving environmental problems. A host ofscientific studies has shown that short-lived chlorinated aliphatic compoundsmake only minor or even insignificant contributions to environmental problemssuch as stratospheric ozone depletion, global warming, "photochemicalsmog", "acid rain" or chloride levels in precipitations(J.A. FRANKLIN and H.W. SIDEBOTTOM).

Are organo-chlorines harmless or harmful? The question seems as irrelevant as asking if natural compounds areharmless and anthropogenic ones toxic.

Ecotoxicity (K. BALLSCHMITER) and toxicity(A. HANBERG) as any other "chemical" property of any compounddepends on the structure of its molecule; chlorinated or otherwise halogenatedcompounds do not escape this rule. Therefore, an undifferentiated banof whole classes of chemical compounds has to be qualified as unscientific.

Even in apparently "homogeneous"families such as the dioxins, toxicity varies considerably with the positionand the number of substituents (Ch. RAPPE). There is thus no scientificfoundation to the amalgamation of all chlorinated compounds as a groupshowing special toxic and ecotoxic properties, no more than one shouldconsider organo-oxygens or organo-nitrogens as a whole as harmful becausehighly toxic warfare agents as sarin or tabun contain these atoms in theirmolecules.

This obviously doesn't mean that organo-chlorinewaste, as any sort of waste, has not to be managed. The problem has beentackled and technical solutions have been developed to reduce byproductsformation by improving the production processes, to destroy and/or valorisethe remaining production wastes (R. PAPP). This has now to be generalizedin the most economic and environmentally friendly ways. In some cases,post-use recycling is being developed and starts to be generalized asfor the recycling of PVC for which "second life" applicationshave been found (G. MENGES).

In conclusion, I would like to add a fewwords formulated by the Nobel laureate Prof. Lord George Porter earlieron. "There is no way that humans can foresee all the consequencesof their actions, .... The only sure foundation for security in this technologicalworld is to have a science base which is continually asking whatever questionsseem interesting and is always there to advise and to act when the needemerges."

It is the responsibility of the scientificcommunity to develop this science base, of the media to help them toinform the public in an understandable and unbiased way, of the publicauthority to take the relevant decisions on the bases of sound scienceand not on emotional reactions and of industry to act responsibly, endorsingproduct stewardship and responsible care. This is true for chlorineand its chemistry as well as it is for all human activities.