Safety_Series_025_1968 - gnssn - International Atomic Energy ...

This publication is no longer validPlease see http://www.ns-iaea.org/standards/(3) The u tiliza tion o f c o m p le x -fo r m in g su b sta n ce s.EDTA is rela tiv ely to x ic and in sm a ll d oses induces h y p o ca l-caem ia. It is th erefore adm inistered in the form of CaEDTA whichis not m etabolized and is rapid ly elim inated in the urin e, w h ereasthe ca lciu m is to a certa in d e g re e exchanged fo r oth er m e ta b o licion s. F o r som e elem ents like plutonium, thorium , yttrium and ther a r e earth s the ch elatin g agent d ie th y le n e -tria m in e -p e n to a ce ta te(D TPA) has proved su p erior to the CaEDTA. P rolonged treatm entwith DTPA effectiv ely rem oves part of deposited plutonium.1.4.6. Effects o f absorbed radionuclidesThe radiotoxic effect of radioisotopes on the organism is a co m ­plex function which depends on a variety o f physical fa ctors, one ofthe m ost im portant of which is the physical h a lf-life of, and thestrength and type o f radiation emitted by, the isotope. The chem icaltoxicity o f the isotop e is a lso som etim es im portant. F o r uraniumits toxicity as an elem ent must be considered in relation to its radioactivep rop erties. With regard to the organism , too, a whole serieso f b io lo g ica l fa cto rs are in volved, such as the m ode of entry o f thera d ioa ctiv e m a teria l, the site o f its d ep osition and the rate o f itselim ination. A nother im portant fa cto r is the age and the assum edrem aining life -sp a n o f the org a n ism .E a rly effectsIn experim ental anim als early effects have been observed afteradm inistration o f lethal d oses of ra d ioactive m a teria ls. They appeared7-10 days after exposure and included m ostly haematopoieticsym ptom s of acute radiation d isea se. There have been observationso f early effects in man after accidental intake of radioactive m aterial(e.g. the acciden tal exposu re of 103 lu m in ou s-dial painters to 90Srinvolved urinary excretion and early haem atological effects as w e ll).Late effectsL ong-term effects follow ing ingestion of sm all amounts of internalem itters m ay be a seriou s p rob lem . The in ciden ce of lungca n cer am ong S chneeberg and Jachym ov uranium m in ers is at least50% h igher than that in the g en era l population. O ther data fro mC olorado Plateau and the St. L aw rence region also strongly suggest51