(seawater for example), whereas soft water cannot have much calcium or 

 magnesium; so these terms should be used correctly and cautiously. 



The matter of hard water versus soft water is left to others, but Terry'^'^has 

 reviewed and summarized known health hazards from sodium ingestion for 

 cardio-vascular, kidney, and liver ailments with emphasis on essential hyper- 

 tension which requires severe limitations of sodium. Problems also arise with 

 some complications in pregnancy and with some metabolic disorders. For 

 healthy people, 270 mg/£ sodium is a reasonable upper limit in drinking water, 

 whereas, 20 mg/Ji is the upper limit for those suffering form hypertension.'*^ 

 Certainly then, there is cause for concern with any buildup in chloride even if 

 some sodium is exchanged for calcium and magnesium. 



Salt for table use, deicing, water softeners, and so on, is usually nearly pure 

 sodium chloride whether from evaporated or rock salt. Nevertheless, minor 

 constituents may pose problems. For example, a Chilean rock salt analyzed by 

 the New Hampshire Water Supply and Pollution Control Commission contained 

 64 parts per million (ppm) zinc and six ppm orthophosphate. Fresh-water fish 

 have a low tolerance for zinc, and phosphate can contribute to eutrophication of 

 ponds and lakes. 



Another aspect of some concern has been possible effects of deicing additives 

 (anti-caking) such as ferric ferrocyanide (Prussian blue) and sodium ferrocyanide 

 and corrosion inhibitors such as certain chromates (apparently no longer used) 

 and sodium hexametaphosphate.'*^ The ferrocyanides, particularly in the sodium 

 form, are somewhat soluble in water, and cyanide is harmful even in low 

 concentrations to some aquatic life. Hexavalent chromium is toxic to humans, 

 and trivalent chromium is toxic to some vegetation. 



IMPLICATIONS FOR THE FUTURE 



Rather than the traditional summary and conclusions, I prefer to close on a 

 more personal note. Clearly, mankind is going to continue using salts containing 

 chloride for a variety of purposes. Very likely, use of road deicing salt will 

 continue, but recent events suggest a trend toward much closer control of 

 quantity and better methods of application. Perhaps substitutes will be found. 

 The hard water versus soft water controversy wiU continue, and maybe it will 

 turn out to hinge on some as yet undetected trace element. Pollution problems 

 wiU not go away, and there will always be combined indifference and hand 

 wringing. 



We do live on a large but finite planet which is not likely to possess infinite 

 capacity to absorb at rapid rates the wastes and by-products resulting from 

 man's activities. It is essential that apparently harmless constituents such as 

 chloride be given consideration at the same time as more harmful substances. In 

 closing, I would point to the reaction against nonbiodegradable detergents which 

 caused water from wells to foam. In response, producers developed a 

 biodegradable detergent that does not cause foaming; however, its products may 

 still be there. We just do not see them any longer. Chloride should be viewed in 

 the same light. It has something to tell us. 



47 id. 



'^TERRY 41-43. 



"^^STRUZESKI 65-70. 



25 



