“Das nested chew treads z = a = Hi i Liebe . . . . a. : * ’ "WMD . * e . ® , Mat stsallese _ ® Rudester Ary Ne bow vo? fy Marsbesllowe u oat hl =“ . 2 ae dimes eee lu fl u . * . . “ . ° . on . = : ‘ 1 ‘ ‘ - . 15 woe Al ‘Vitae alter oxpmmiate (caret Viguie U5. ‘Time of appearince of thyreid lesions in Marshallese. Expaned atawe SOM. lectebeiey +. Magalige nant Exposed ate 1G: @, beats a tidignaat, View read cheat cpacdss Figure 44. Tncidence of benign thyroid tchales. paruy related to the smaller contribution ta the close from short-lived isotopes of iadine, Neverthe: less the Ana Arbor children in’ Elempelaana’s studs!" had an increased incidence of thyroid tue mors follawing a mean dose of only JU rads to the gland (Figure 44). and more recently Modan et al and Harleys coal!!!) have reported atnincreased incidenceof thyraid tumors in chiklren who had received about 6.3 rads ta dhe thyroid gland during x-ray treatment af the scalp for tungus infecuon, Modan etal. state that “one would stranudy suspect a mune pidemic of thy coil adenama” in the group studied, In considering the risk data of Hempehiiann’s and Modan'’s groups. the large clement af Jewish peaple ¢u lio have in- creased susceptibility to thyroid: tumors) should be kept lamind. Absa. Hempelnann’s were irradi ated as infants and therctore represent only a thar: TOWade Taunige. 1, Latent Period ln Figure 45 the development of thyrotd abnor. iualities is plotted according to radiaion dese and development of radiation-induced thyroid tumors. Theroid cancer bas been reported as long as 40 vears after radiation exposure. 14 Correlation with sex showed tbat slightly: mare exposed Rongelap females (18 of 45) developed thyroid lesions than did wales (11) of at). AY chree cases of cancer of the thyroid were tn females, Vhe chyreid gland is geaerally thought to be Inore sensitive to radiation ducing childhood,bet Pochin? ™ estimates a percent incidence per 10U rads of (<5 te 1.0 for adults and 1.3 foe children. Certainly the largest number of benign lesions ov curred in the Abarshallese children. Phas ts prab- ably due mainiy ta the smadiier size ofthe thyroid wlands resulting in kirger doses per gram of gland. Doniach?*" theorizes that thyroid tumors are produced by aa initiating factor (radbation) plus a prowmeting factor CUSED) which dicreases mitosis and colances the expression af a possible matiz- nant clone. In addition, in clalceen the qroweh tector nay be iniportaat. since ab maturity the thy. roid weighs abet JO tines as much as at birth. ‘Vhese factors would increase the chances for mae livraat trasfortsation. Phe lower meidenee of cancer ot the thyroid io children thar cp achalts tay be rebated te the lack of dase dependences of Hone aller exposures the Latent period appeses to The carcrogonie cleat af radianan at high doses. be honger with lower deses. Figures 44 and 47 show Seve the celitionship between dose and age at devel- ob raetation (both x gays scacl ravdicdecdine ) ae case opment of thy raid lesions. Vhese data indicate that the radiionsanduced lesions occur at earlier ages in the exposed Rongehip people than inthe Curik oe imexposed yroups. Tn the lather groupes salient albthe thyreid nedulirites develop in the older people. Recent data of Elem pelosi oo al ine dheate that whe latent period may be > 30 years for binvestivators lave slioowo thaw highs dlases SCha with a lower incidence of abroad madi. aaney chan lower doses, pessibly because the binh doses praduce cnonuuh cell destruction te prochide malivnant tansformatiqn Seles ln opis mav be the case with Mirshallese children. This been noted that lollawing treatment of bypertivraisin with large doses af radioiodine, although