Drinking Water and Health, Volume 1 (1977) / Chapter Skim
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I APPROACH TO THE STUDY
I APPROACH TO THE STUDY
Pages 9-18
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From page 9... ...
The Act also directs the Administrator of the Environmental Protection Agency to arrange with the National Academy of Sciences, or other appropriate organization, to study the adverse ejects on health attributable to contaminants in drinking water. Although the high quality of drinking water in the United States is recognized throughout the world, the law is an expression by the Congress of the concern of many citizens about maintaining the quality of public water supplies in this country.
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From page 10... ...
The economic or technological feasibility of controlling the concentration of these constituents was outside the scope of the study. The health elects associated with some methods of disinfection were noted, but the relative effectiveness and potential hazards associated with the various methods of water disinfection were not evaluated.
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From page 11... ...
9. For materials with special health benefits, what concentrations will maximize these benefits, while keeping the health risk associated with them at an acceptably low level?
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From page 12... ...
The scientific methods and criteria we have used for evaluating long-term ejects and risks in man are described in Chapter II, "Chemical Contaminants: Safety and Risk Assessment" and in the chapters concerning each group of contaminants. Most of the experimental results on which the current knowledge of toxicity rests are based on observed effects on man and animals of doses and dose rates that are much larger than those that correspond to the usual concentrations of harmful materials in drinking water.
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From page 13... ...
PARTICULATE CONTAMINANTS Finely divided solid particles of mineral and organic composition are commonly found suspended in some drinking water, particularly those supplies that do not practice coagulation and filtration. To discover whether or not the long-term ingestion of these materials in water is likely to produce adverse ejects on human health, their occurrence, composition, and properties were reviewed.
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From page 14... ...
INORGANIC SOLUTES The Interim Primary Drinking Water Regulations list maximum allowable concentrations for six metallic elements barium, cadmium, chromium, lead, mercury, and silver. Ten additional metals were reviewed in this study beryllium, cobalt, copper, magnesium, manganese, molybdenum, nickel, tin, vanadium, and zinc.
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From page 15... ...
The ADI is an empirically derived value that reflects a particular combination of knowledge and uncertainty concerning the relative safety of a chemical. The uncertainty factors used to calculate ADI values in this report represent the level of confidence that can be justified on the basis of the animal and human toxicity data.
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From page 16... ...
RADIOACTIVE CONTAMINANTS Because the presence of ionizing radiation is one of the standard features of the earth's surface, the adverse effects on health that may be ascribed to radioactive contaminants of drinking water were assessed in relation to the average background radiation dose, from all sources, of 100 mrem per year. Previous estimations of the biological effects of the background radiation on human health were reviewed in the light of more recent scientific knowledge and used to calculate the magnitude of three kinds of adverse health ejects that radiation can produce; namely, developmental and teratogenic ejects on the fetus, genetic disease, and somatic (principally carcinogenic)
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From page 17... ...
This report is concerned only with water used for drinking. Although all contaminants may cause problems when present in water used in health care facilities, the health hazards associated with such diverse uses of water as in humidifiers, kidney dialysis units, laundries, heating and cooling equipment, or many special uses that require further treatment of tap water, have not been considered.
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