will not seriously affect most fish. Concentrations up to 5,000 ppm have been
consumed in drinking water by rats without ill effects. Thus, concentrations injurious to
health are far in excess of those that impart an unpleasant taste.
PESTICIDES AND CHEMICAL WARFARE AGENTS
a. Pesticides. Because of the increased use of synthetic organic pesticides
over the past 30 years, the EPA has established interim standards for maximum
concentrations of pesticides in treated water. Since the available data concerning the
effects of pesticides on humans are not complete these standards are constantly under
revision. The maximum permissible concentrations are shown in Table 4-4.
b. Chemical Warfare Agents. STANAG 2136 and SOLOG Agreement 125
establish maximum permissible concentrations of chemical warfare agents (CW) agents
in drinking water consumed under field (combat) conditions. These concentrations are
shown in Table 4-4.
The effects of radiation on human beings are viewed as harmful, and any
unnecessary exposure should be avoided. Major sources of radioactivity in drinking
water supplies are Radium-226, found only in certain ground waters or in industrial
wastes containing radium; and Strontium-90, a constituent of delayed fallout from
a. Physiological Effects of Radioisotopes. Radioactive substances
(radioisotopes) emit gamma rays, alpha particles, beta particles, or combinations
thereof. Radium-226 is an alpha emitter, whereas Strontium-90 is a beta emitter. Both
alpha and beta emitting material may be deposited as residual radiation in drinking
water. Alpha emitters are particularly hazardous when taken internally, because of their
deposition of energy in very small volumes of tissue and in specific organs. Beta
particles are also very hazardous when taken internally; they, too, are absorbed by the
body tissues. Generally speaking, however, the body is able to tolerate a slightly
greater quantity of beta emitters than of alpha emitters, because the beta emitter
deposits its energy over a greater tissue volume. An exception is the beta radiation
from Strontium-90. This radioisotope is much more hazardous than other beta emitters,
in that Strontium-90 is readiIy deposited in newly forming bone.
b. Radiation Limits.
(1) Water supplies are approved without further consideration of Radium-
226 and Strontium-90 radioactivity intake from other sources when the water contains
not more than:
Radium-226: three uuc/l (micromicrocuries per Iiter).