- 43 ~- qrcc TABLE V Occupational Exposure Guidance for Insoluble Alpha Emitters, Maximum Permissible Lung Particle Burden (MPLPB) 7? Cancer risk due to 5 rem/yr _ whole boay exposure /3 Assumed Risk in Particle 1/1000 1/2000 4.5x1074 0.45 0.9 107-3 l. 2. 2.3 4.6 (best estimate) 2.3x1072 1/10,000 ° 4.5 £10. 23. o largest MPLEB in Table V, 23 particles, represent a reduction of the existing MPLB and MPC, by a factor of 10,000. It is recommended here that the best estimate of the effects of uniform exposure by the BEIR Committee be used together with a risk of cancer induction of 1/2090 per hot particle in détermining the MPLPB for insoluble alphaemitting radionuclides in hot particles. This is a somewhat arbitrary compromise and is not the most conservative value that could be recommended. Thus, the recommended MPLPB for occupational exposure from hot particles of alpha- 77/ The number of particles required to give a cancer risk equal to that from uniform radiation. 78/ Source: BEIR Report, Op. cit., p. 91. The MPLFB corresponding to a lung cancer risk of 3x1075 due to 15 rem/yr lung dose [BEIR Report, Op. cit., p. 156] are 0.03, 0.06 and 0.3 for assumed particle risks of 1/1000, 1/2000 and 1/10 ,C09S respectively.