terial into water" {10, 3). Although the analytical 

 procedure then in use leaves much to be desired 

 from the standpoint of simplicity, reproducibility, 

 and interpretation, it was the best available at that 

 time. The analytical procedure has been improved 

 since then and the newer technique (,1,2) gives 

 substantially higher results than the one originally 

 used. The defined method of treatment generally 

 removes very little of the CCE present in the raw 

 water. In many instances there is an increase dur- 

 ing treatment. Whether this is real or apparent is 

 not known. 



The permissible criterion of 0.15 mg/1 recom- 

 mended is based on use of the procedure cited in 

 Drinking Water Standards (10). We do not as 

 yet have sufficient information on which to base a 

 recommended limit using the lower flow rates and 

 sample volumes of the newer procedure. When this 

 information is available, a change in the criterion 

 is advisable. This limit is generally attainable 

 where vigorous efforts at pollution control are 

 carried out. 



Paragraph 19: Methylene Blue Active Substances 



This is an operationally more precise name for 

 substances discussed in Drinking Water Standards 

 (10) as alkyl benzene sulfonate. The permissible 

 criterion is the same as the limit recommended in 

 those standards. Those standards have been re- 

 vised to reflect this change in nomenclature. 



Paragraph 20: Oil and Grease 



It is very important that water for public water 

 supply be free of oil and grease. The difficulty of 

 obtaining representative samples of these mate- 

 rials from water makes it virtually impossible to 

 express criteria in numerical units. Since even very 

 small quantities of oil and grease may cause 

 troublesome taste and odor problems, the Sub- 

 committee desires that none of this material be 

 present in public water supplies. An additional 

 problem attributable to these agents is the un- 

 sightly scumlines on water treatment basin walls, 

 swimming pools, and other containers. 



Paragraph 21: Pesticides and Herbicides 



Consideration was given by the Subcommittee 

 to three groups of pesticides: the more common 

 chlorinated hydrocarbons, herbicides, and the 

 cholinesterase-inhibiting group which include the 

 organic phosphorus types and the carbamates. The 

 permissible levels are based upon recommenda- 

 tions of the Public Health Service Advisory 

 Committee on Use of the PHS Drinking Water 

 Standards. These values were derived for that Com- 

 mittee by an expert group of toxicologists as those 

 levels which, if ingested over extensive periods, 

 could not cause harmful or adverse physiological 



changes in man. In the case of aldrin, heptachlor, 

 chlordane, and parathion, the Committee adopted 

 even lower than physiologically safe levels; 

 namely, amounts which, if present, can be detected 

 by their taste and odor. It should be noted that this 

 National Technical Advisory Subcommittee on 

 Public Water Supplies is not a group of toxico- 

 logical experts. Hence, the promulgation of addi- 

 tional criteria by the Public Health Service would 

 also be accommodated by this Subcommittee, 

 tempered — as was done above — by its experience 

 and judgment in the area of water treatment, as, 

 for example, in public acceptance of organoleptic 

 properties. 



The limit for the cholinergic pesticides is estab- 

 lished relative to parathion and is expressed as 

 0.1 mg/1 parathion equivalent. This equivalence is 

 the ratio that a given pesticide of this group has to 

 parathion as unity in its cholinesterase inhibiting 

 properties. This makes it incumbent upon an ad- 

 ministrator of this limit to determine the pesticide 

 involved and to obtain expert toxicological opinion 

 on its parathion equivalence. Nearly all the or- 

 ganophosphorus compounds and the cholinergic 

 carbamates have high acute toxicity to mammals 

 and some have even higher toxicity to fish. Inges- 

 tion of small quantities of these compounds over 

 long time periods causes damage to mammalian 

 central nervous systems. Many organophosphorus 

 pesticides hydrolyze rapidly in the environment to 

 harmless or less harmful products. The hazards 

 from the chlorinated hydrocarbon pesticides in 

 water results from both direct effects, because they 

 tend to persist in their original form over long 

 periods, and indirect effects because they may be 

 concentrated biologically in man's food chain. 

 The values which were selected by the Public 

 Health Service as limits for this group of pesticides 

 are, however, set with substantial safety factors 

 insofar as they adversely affect the human body. 

 Generally, fish are more sensitive to this group of 

 pesticides and, therefore, may serve as a rough 

 method for determining when the chlorinated hy- 

 drocarbon pesticides content of water is approach- 

 ing a danger level. See the report of the Fish, 

 Other Aquatic Life, and Wildlife Subcommittee 

 for pesticide limits relative to maintaining healthy 

 and productive aquatic life. 



It should be noted that limits for pesticides and 

 herbicides have been set with relation only to 

 human intake directly from a related domestic 

 water supply. The consequence of higher and pos- 

 sibly objectionable concentrations in fish available 

 to be eaten by man due to biological concentration 

 is considered not within the scope of the charge to 

 this Subcommittee. 



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