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<br />from silver iodide over an extended period of time." [1, <br />p. B-15] <br /> <br />"The Envi ronmental Protection Agency has reported that sil ver <br />and silver compounds have a rather low order of both acute and <br />chronic toxicity to experimental animal s and to man. The <br />pr i nc i pa 1 effect of 1 arge quant it i es of silver in the body is <br />argyria, 'a skin discoloration that results when hundreds of <br />times the proper amounts of si lver compounds are injected or <br />taken orally. Silver becomes deposited under the skin and stays <br />there; it kills bacteria that might be present, but, naturally, <br />no one wants gray skin.' [49] <br /> <br />"Although the air concentration of silver which will result in <br />argyria is not accurately known, the TLV (threshold limit value) <br />has been set at 0.01 mg/m3. <br /> <br />"No systematic toxicity attributable to silver has been reported <br />in workers who are occupationally exposed to it even though <br />accidental and suicidal ingestion and medical overdoses of <br />various silver compounds have ~roduced poisoning. Thus, a <br />report from the Health Effects Research Laboratory of the <br />Environmental Protection Agency concludes that silver and silver <br />compounds apparentl y do not pose a si gni ficant envi ronmental <br />health problem though large amounts are discharged into the air <br />and otherwise lost into the environment [50]. <br /> <br />"In the concluding section of Appendix B, the Skywater <br />programmatic Final Environmental Statement states: <br /> <br />'Aggregate impacts of Skywater and other programs. The <br />quest i on must be addressed whether the Skywater experi- <br />mental program and operational programs of precipitation <br />management that may ensue from it might, when aggregated <br />with other programs of weather modification dispersing <br />silver iodide, have environmental impacts that would not <br />ensue from the other programs alone. <br /> <br />'Suchoverlapping of silver accumulations from different <br />weather-modification operations is most likely to come <br />about in connection with suppression of hail and severe <br />storms. Some operations for suppression of hai 1 have <br />involved releases of silver iodide at rates and in concen- <br />trations exceeding those of Project Skywater experiments by <br />tenfold or more, and at least one has been conducted over <br />the same study area as one of the Skywater pilot projects. <br /> <br />IOn the basis of the information now available, it does <br />not appear that, if overlapping of precipitation-management <br />and hail-suppression projects were to double the rate of <br />accumulation of silver, such a situation would materially <br />alter the conclusions reached regarding Project Skywater <br /> <br />24 <br />