Experience in 25 countries shows, not surprisingly, that the trend everywhere is towards tightening legislative control on waste discharges to the environment. What is comparatively recent, however, is the rate of change in the standards required under these laws. This stems partly from the elevation of environmental protection to a political issue within the last quarter century, a new awareness among environmental pressure groups enhanced by instant communications world-wide, an international knowledge of what is - or should be - technically attainable in effluents from various manufacturing processes, and technology transfer and sometimes funding encouraged by the international agencies like those of the United Nations.
After a brief consideration of the derivation of standards 21 cases are noted in which the actual application of standards has been questionable. In view of the significant effect of effluent standards upon manufacturing costs it is important that standards are both rational and necessary. Approaches to the minimizing of industrial effluent discharges benefit both the discharger and the receiving environment.