swee; 4 to & cycles par second. The ;robabliity of « vartiele remaining within one mailiimeter sone for as mich eas one-half hour appeare te be vanishing small. .. Proteetion wil. also be rovided by the auous lining which is ‘tself renewed several tine: am hour." Accepting the estinstes above and the methods illustrated in appendices E and F, it may be 4 conyuted that about #3 reps would be delivered te the surfaes of an inmagin- ary stationary sphere one millimeter te radius by a 25 afcron particle (@/ ~~ 4 uicrocuries), " Larger doses wd be delivered closer to the particle but with the relatively rapid movement of the .article, it does net that large doses will be delivered tc « great munber of cells. appear Multirle exposures might ocour fror a’: itional part cles but again this risk is difficult to evaluate Foo. Consideratle effort is being directed toward the study of seontan ination of food froz fallout. One element of wajor concern is Sr, It has been estimated thet if one ware to subaist entirely onfood& wm froz selis containing about one slcroeurie er square foot of or* , of calciuz per acre (1,000 pounds tnat over a j;ertod of years there would aecwmlate in the muman akeleton 4 vedy burcen of one aiarocurie ef srs, Seils taken from » gbout wiles fros the Wevada Iroving Grounds, now show a concentration of misrocuries per square font *‘rivyate commmnication, L. a. Dear, 0 Beltsville, Marvlend, Apri] <3, 1°. . “e,artaent of agriculture,