Biological Effects of Radiation nonionizing radiation bumps e

Biological Effects of Radiation nonionizing radiation: bumps e– to higher energy levels or heats molecules; less dangerous ionizing radiation: knocks e– out of molecules; more dangerous -- e. g. , a, b, g, x-rays, high-frequency UV

(1) creates H 2 O+ (2) H 2 O+ + H 2 O . : -- sequence of action in living tissue (: O–H) H 3 O+ + OH The free-radical initiates a number of chemical rxns. that disrupt cell function. neutral free-radical w/unpaired e– -- the tissues most damaged by radiation are the ones with cells that rapidly reproduce: bone marrow, lymph nodes -- low doses over a long time can induce cancer, which is… the uncontrolled reproduction of cells.

Units for Radiation Doses 1 bequerel (Bq) = 1 disintegration/sec 1 Curie (Ci) = 3. 7 x 1010 disintegrations/sec 1 gray (Gy) = absorbing 1 J/kg of tissue 1 rad = absorbing 1 x 10– 2 J/kg of tissue “radiation absorbed dose” Since the various types of radiation damage tissue with various degrees of efficiency, each type has its own relative biological effectiveness (RBE). photon or b RBE = 1 n 0 RBE = 10 a RBE = 20 “roentgen equivalent – man” rem = RBE x rad

Radon -- an a-emitter from the decay of radium in rocks and soil -- very dense; seeps into basements and is readily inhaled Ra-226 a radon formed Rn-222 a Po-218 radon this, too, is an emits a radiation a-emitter -- estimated to be responsible for ____ 10% of U. S. lung cancer deaths