Exposure in DAC-h

DOE-STD-1121-98

Stochastic ALIs, SALI, for inhalation, can be computed from DACs in 10 CFR 835 Appendix A provided

the notation "St" appears in the right-hand column of Appendix A of 10 CFR 835 for the DAC in

question.

If not, SALI values can be found in Federal Guidance Report 11 (Eckerman et al. 1988) or the ICRP

Publication 30 series. These SALI values are valid for 1 :m activity median aerodynamic diameter

(AMAD) aerosols. ICRP 30 gives a methodology for adjusting the SALIs for other particle sizes (ICRP

1979a). If the more recent respiratory tract model and dosimetric methods are used (ICRP 1994a),

consideration should be given to adjustments for activity median thermodynamic diameter (AMTD) for

aerosol size distributions below 0.1 :m, in the size region where the diffusive behavior of particles

predominates.

7.5.2 Exposure in DAC-h

Often, before an intake is computed, an exposure in terms of DAC-h is evaluated. The exposure, E,

(22)

For an aerosol whose activity median aerodynamic diameter (AMAD) is 1 :m, the committed effective

dose equivalent HE,50 is

(23)

The committed dose equivalent to limiting tissue T (as listed in the right-hand column of Appendix A of

10 CFR 835) is

(24)

If the only DAC available is a nonstochastic DAC, then HE,50 cannot be assessed using that DAC and air

monitoring data. All that can be stated with certainty regarding the committed effective dose equivalent

from an intake of 1 NALI (2000 DACn-h) is

(25)

For thyroid and bone surfaces, wT = 0.03, an intake of 1 NALI (2000 DACn-h) leads to HE,50 of

(26)