Research Product

Halogenated hydrocarbons, and particularly DDT, DDE and PCBs, are transported to a significant extent through the atmosphere and have been detected in all regions of the world. The substances, which have been produced only by man, are now as widely distributed as natural substances, although, in the case particularly of the PCBs, their use is confined to limited areas of the world. Natural processes of atmospheric transport lead inevitably to the redistribution of halogenated hydrocarbons to areas where no use exists or can be anticipated, and it is to be expected that in these areas the background level will increase slowly, although not necessarily to concentrations at which biological effects could occur. Nevertheless, it may be considered prudent to monitor concentrations in such areas to assess the extent of contamination and to measure the trend in concentrations of substances such as PCBs, DDT, and DDE over a long period. The panel discussed both the question of alternatives to bivalves as material for assessing pollution in coastal waters and strategies required for determination of any organohalogen contamination in the samples selected. As the organohalogen group includes several hundred compounds of various types and uses, and of widely differing chemical properties, the panel decided that only a limited number of more persistent compounds with widespread occurrence should be measured in any monitoring program. The specific compounds will be determined by use patterns in the respective areas, although in all cases PCBs should be analyzed.