1 

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES 

CENTERS FOR DISEASE CONTROL 

NATIONAL INSTITUTE FOR OCCUPATIONAL 

SAFETY AND HEALTH 

+ + + + + 

ADVISORY BOARD ON RADIATION AND 

WORKER HEALTH 

+ + + + + 

WORK GROUP ON SCIENCE ISSUES 

+ + + + + 

TUESDAY 

APRIL 17, 2012 

+ + + + + 

The Work Group convened in the 

Brussels Room of the Cincinnati Airport

Marriott, 2395 Progress Drive, Hebron,

Kentucky, at 9:00 a.m., David B. Richardson,

Chairman, presiding. 

PRESENT: 

DAVID B. RICHARDSON, Chairman*

R. WILLIAM FIELD* 

RICHARD LEMEN* 

WANDA I. MUNN 

GENEVIEVE S. ROESSLER 

PAUL L. ZIEMER 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com
 

 

2 

ALSO PRESENT: 

TED KATZ, Designated Federal Official

IULIAN APOSTOAEI, ORAU Team

OWEN HOFFMAN, SENES

DAVID KOCHER, ORAU Team

JENNY LIN, HHS*

JOHN MAURO, SC&A*

JIM NETON, DCAS

SUSAN REUTMAN, DCAS

DANIEL STANCESCU, DCAS

JOHN TRABALKA, ORAU Team 

*Participating via telephone 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com
 
 


 

3

 CONTENTS 

Welcome.....................................4 

Presentation and Discussions................5 

Discussion................................114 

Adjournment...............................220 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com
 
 

 

 

 

 

4 

1 
 P-R-O-C-E-E-D-I-N-G-S 

2 
 9:02 a.m. 

3 
 MR. KATZ: Okay. The agenda for the 

4 
 meeting is posted on the website, NIOSH 

5 
 website, under the Board meetings section. 

6 
 And, David, it's your meeting. 

7 
 CHAIRMAN RICHARDSON: Okay. Well, 

8 
 thanks, everybody, and I'm sorry that I can't 

9 
 be there. 

10 I guess as a starting, I wanted to 

11 
 see if there are additions to the agenda or 

12 
 changes. Ted had suggested there might be 

13 
 some issues with scheduling, but, hearing none 

14 -

15 
 MR. KATZ: Okay, no suggestions. 

16 Nothing in the room. 

17 
 CHAIRMAN RICHARDSON: Okay. Then 

18 
 what I'd propose doing is starting with the 

19 
 presentation from SENES. I think that will -

20 
 I had a chance - I received the slides last 

21 
 night. So, I think that will be a really 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

5 

1 
 useful starting point to kind to get us on a 

2 
 common footing. 

3 
 And then we can move to a 

4 
 discussion following that and work on ideas 

5 
 about how to move forward with this. 

6 
 MR. KATZ: That sounds good. And 

7 
 let me just note for the other Board Members 

8 
 on the line, I sent to you that presentation 

9 
 just this morning. 

10 
 So, I sent it to your - whichever 

11 
 email you most frequently use. Mostly 

12 personal ones. Okay. 

13 
 DR. HOFFMAN: Okay, so this is Owen 

14 
 Hoffman and I'd like to introduce our 

15 presentation. 

16 
 The presentation is really in two 

17 
 parts. You've got all the slides together, 

18 
 but what we want to do is to first discuss the 

19 
 role of the low-dose and dose-rate 

20 
 effectiveness factor in IREP. 

21 
 And then after that, to respond to 

22 
 any of the questions that you have regarding 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

6 

1 
 our draft report on the state of scientific 

2 
 knowledge on uncertainties in the low-dose and 

3 
 dose-rate effectiveness factor. 

4 
 And so, our presentation is 

5 
 prepared in two parts. One is to introduce 

6 
 how it's used in IREP, and the second is to 

7 
 summarize findings and results within our 

8 
 draft report to NIOSH. 

9 
 To start the presentation, I've 

10 
 asked my colleague Dr. Iulian Apostoaei to 

11 
 begin. Iulian is developing a case of loss of 

12 
 voice. And if something happens in the middle 

13 
 of this presentation, then Dr. John Trabalka 

14 
 is prepared to step in, David Kocher and 

15 myself. 

16 DR. TRABALKA: I will begin. 

17 
 DR. APOSTOAEI: I think he needs to 

18 start right now. 

19 DR. HOFFMAN: You will step in. 

20 DR. TRABALKA: Yes, I am. 

21 DR. HOFFMAN: Okay, go ahead. 

22 
 DR. TRABALKA: Iulian prepared a 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

7 

1 
 revision to the presentation that he gave to 

2 
 the Health Physics Society meeting in July 

3 
 that covered our work, provided a summary of 

4 
 our work. 

5 
 By the way, I tend to be soft6 
 spoken. So, if anybody can't hear me, let out 

7 
 a yell and I'll start increasing the volume. 

8 
 And he was going to give the 

9 
 presentation. But since he's come down with 

10 laryngitis, I will attempt to take over. 

11 
 As Owen said, we're going to kick 

12 
 it off by trying to explain how the DDREF is 

13 
 used in IREP, and then cover some of your 

14 
 questions and talk about what we've been 

15 doing. 

16 
 One question that we heard 

17 
 yesterday is, where is Section 6.3? Well, 

18 
 material in part of Section 6.3, Appendix D, 

19 
 which you did not get, and the last couple of 

20 
 pages in the extended summary, covers pre21 
 decisional information on potential new DDREF 

22 distributions for IREP. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

8 

1 
 Since this material has not gone 

2 
 through an external peer review, it has been 

3 
 withheld at this time. 

4 
 However, inadvertently Section 6.31 

5 
 and 6.32 were not included in your package. 

6 
 These cover summaries of the information that 

7 
 we used in developing DDREF distributions, our 

8 
 rationale for choosing them, how we prioritize 

9 
 them, how we waiver them. And I think it 

10 
 would be very useful if those two sections 

11 
 could be made available perhaps even at a 

12 later date. 

13 
 We had to send this draft up to 

14 
 NIOSH in fairly short notice and there are 

15 some editorial-type errors as well. 

16 
 So, we could probably provide a 

17 
 revised copy that has those fixed and these 

18 additions, if NIOSH so wishes. 

19 
 We have been trying to get external 

20 
 peer review prior to a formal peer review 

21 through the NIOSH process. 

22 
 Our report has been shared with an 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

9 

1 
 ICRP Committee that was interested in 

2 
 developing DDREF several years ago. 

3 
 The earliest version they got 

4 
 didn't have Section 5 or any part of Section 6 

5 
 - Section 5, by the way, covers 

6 
 epidemiological studies that can be used to 

7 
 estimate DDREF - but I got some very good 

8 
 feedback from Dr. Michael Fry, a 

9 
 radiobiologist emeritus from Oak Ridge 

10 National Laboratory. 

11 
 And so, the current draft reflects 

12 
 some - his feedback and he provided some very 

13 useful information for us. 

14 
 We also had gotten a revised 

15 
 version of our report that included Section 5, 

16 
 and those first two sections of 6.3 was 

17 
 provided at a later date to the ICRP 

18 
 Committee, and also to Peter Jacob who is 

19 
 leading a team that's preparing the German 

20 
 version of IREP and who is also heavily 

21 
 involved in an UNSCEAR effort, and we did get 

22 
 feedback from Peter on the section in our 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

10 

1 
 report that critiques his synthesis of 

2 
 epidemiological studies. The version in the 

3 
 report reflects the version after his comments 

4 
 had been incorporated. 

5 
 I think it's safe to say that we're 

6 
 still at somewhat of a disagreement with Peter 

7 
 over some of the issues, but that's water 

8 
 under the bridge. 

9 
 Well, anyway, let's proceed to talk 

10 
 about the use of DDREFs in IREP. That's this 

11 slide. 

12 
 The DDREF is an adjustment factor. 

13 
 It's a divisor that is used to reduce the 

14 
 level of risk based on a hypothesized 

15 
 reduction of risk at low doses and dose rates. 

16 
 And that's based on an inherent 

17 
 linear quadratic model that is used typically 

18 
 for estimating how radiation produces - for 

19 dose responses for radiation. 

20 
 It's not applied to leukemia, 

21 
 because a linear quadratic model is used for 

22 
 leukemia. So, it's inherent in that dose 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

11 

1 
 response model. 

2 
 Let's go on to the next slide. 

3 
 Now, this is a flow diagram that you should 

4 
 have received - the first part of the flow 

5 
 diagram that you should have received a copy 

6 
 of. 

7 
 And at the top of the flow diagram, 

8 
 there are two branches. One branch goes to 

9 
 high-LET radiation like neutrons and alphas. 

10 And for those, the DDREF is defined as one. 

11 
 For low-LET radiation, it branches 

12 
 again. That's covering x-rays, gamma rays and 

13 electrons. 

14 
 Again, if the cancer type is 

15 
 leukemia, we have the dose response model 

16 
 that's linear quadratic that implicitly 

17 includes the DDREF. So, none is applied. 

18 
 For other cancers depending on 

19 
 whether the exposure is chronic or acute, we 

20 have two different ways of dealing with it. 

21 
 We have two different distributions 

22 for DDREF in IREP for chronic exposure. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

12 

1 
 One covers breast and thyroid 

2 
 cancers, and one covers other solid cancers. 

3 
 And I'll have a slide that covers that 

4 
 specifically in just a minute. 

5 
 Now, on the other side is 

6 
 information that suggests that there is an 

7 
 approach to - basically what happens is, there 

8 
 are a couple of equations in IREP that attempt 

9 
 to take risks at higher doses above 200 

10 
 millisieverts and produce a smooth transition 

11 
 to a chronic DDREF when the exposures are 

12 
 acute. And the acute exposures have to be 

13 less than 200 millisieverts to be considered. 

14 
 Let's go ahead to the next slide. 

15 
 This shows the DDREF distributions in IREP for 

16 chronic exposures. 

17 
 For breast and thyroid cancers, 

18 
 there is a more limited range on potential 

19 
 estimates of DDREF and there's higher weights 

20 to values between one and two. 

21 
 For other solid tumors, the range 

22 
 is extended up to values of five. You'll 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

13 

1 
 notice this is a set of discrete values rather 

2 
 than the continuous distribution that's often 

3 
 used for DDREF. 

4 
 MEMBER ZIEMER: Can we ask questions 

5 
 as we go along? 

6 
 DR. TRABALKA: Anytime. Anytime. 

7 
 Fire away. 

8 
 MEMBER ZIEMER: Just back up just 

9 
 one minute. 

10 On the 20 millisievert value -

11 DR. TRABALKA: 200. 

12 MEMBER MUNN: 200. 

13 
 MEMBER ZIEMER: 200, I always have 

14 to convert that. 

15 
 MEMBER MUNN: I do too. You're not 

16 
 alone. 

17 (Laughter.) 

18 
 MEMBER ZIEMER: But you're talking 

19 
 about acute exposures above that, and isn't 

20 
 that always a question as to whether you 

21 
 should be in sieverts or grays when you get up 

22 
 to high acute exposures, for example, 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

14 

1 
 exposures at the level of the Japanese 

2 
 survivors? 

3 
 Because the sievert itself has a 

4 
 quality factor, which it's sort of related 

5 
 here. So - but it's not a dose-rate factor, 

6 
 but I'm just asking about nomenclature here. 

7 
 DR. HOFFMAN: Basically the -

8 
 MEMBER ZIEMER: 20 rads is probably 

9 
 all right, but -

10 
 DR. HOFFMAN: The fundamental unit, 

11 
 Paul, that's used for risk estimation in IREP 

12 is the gray. 

13 I mean, the dose 

14 
 reconstructionists put together sieverts, but 

15 
 then they - the ICRP W sub R weighting factors 

16 
 are used to divide by whatever sievert is 

17 
 input so that basically, the basic unit that's 

18 used for risk assessment is the gray. 

19 MEMBER ZIEMER: Okay. 

20 
 DR. HOFFMAN: Probably if you've 

21 been following the way -

22 
 MEMBER ZIEMER: I think in your 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

15 

1 
 paper you use gray. And then when you talked 

2 
 about sieverts, I was wondering if -

3 
 DR. TRABALKA: I think mostly in 

4 
 grays myself. 

5 
 MEMBER ZIEMER: I think you need to 

6 
 go back to roentgens and rads and then we'll 

7 
 understand. 

8 
 MEMBER ZIEMER: Sorry to interrupt. 

9 
 DR. TRABALKA: Not at all. Stop me 

10 anytime. 

11 
 If you've been following the 

12 
 iterations of the studies of the Japanese A13 
 bomb survivors, you will notice that they have 

14 
 changed from the use of millisievert to - from 

15 sieverts to grays. 

16 MEMBER ZIEMER: Grays, right. 

17 
 DR. TRABALKA: Because they're not 

18 using the quality factor that's applied -

19 MEMBER ZIEMER: Right. 

20 
 DR. TRABALKA: - to produce a 

21 sievert, for example. 

22 MEMBER ZIEMER: Okay. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

16 

1 
 DR. TRABALKA: We're not done with 

2 
 that one yet. 

3 
 For other solid tumors, the bulk of 

4 
 the solid tumors in IREP, this distribution is 

5 
 used. It's got a lower - applies lower 

6 
 weights to values between one and two. And 

7 
 the 90 percent confidence interval is about 

8 
 one to three, for example, the equivalent. 

9 
 Okay, go on to the next one. This 

10 
 is the approach that is - and you don't need 

11 
 to worry about these equations, because I'm 

12 
 going to show you a figure that shows how this 

13 works. 

14 
 These are the equations and the 

15 
 approach that takes a dose somewhere between 

16 
 30 and 200 millisieverts and converts it to a 

17 
 chronic DDREF. 

18 And if you go to the next slide, 

19 
 this shows how DDREF changes as a function of 

20 dose. 

21 
 So, when you're at 200 

22 
 millisieverts, DDREF is inherently one. No 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

17 

1 
 issues. 

2 
 As you decrease the dose, you begin 

3 
 to increase the potential DDREFs. And this 

4 
 simply shows those discrete values of DDREF 

5 
 that were shown in the previous distribution 

6 
 for other solid cancers and how they approach 

7 
 to the final chronic DDREF as a function of 

8 
 dose. And I think questions were asked about 

9 
 that in the material that we received. 

10 
 Does this figure answer those 

11 questions? 

12 
 DR. KOCHER: The basic idea behind 

13 
 this is that you - it doesn't make sense to 

14 
 introduce the full DDREF at one dose, and a 

15 microsievert above that have no DDREF. 

16 
 It's just kind of a continuous 

17 
 phasing in. You don't get the full effect 

18 until you get to zero dose. 

19 
 DR. TRABALKA: But on this figure, 

20 
 you can see that at about one to ten milligray 

21 
 you have the full effect of the chronic DDREF 

22 
 expressed for an acute exposure, or for 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

18 

1 
 fractionated acute exposures that are 

2 
 separated by five hours in time. 

3 
 Okay. Everybody clear on this one? 

4 
 MEMBER ROESSLER: I think I need to 

5 
 study it a bit. 

6 
 DR. TRABALKA: It's a lot of 

7 
 information at one time. 

8 
 MEMBER ROESSLER: If you don't look 

9 
 at the -

10 DR. HOFFMAN: Something like this is 

11 
 second nature to us, but it may be difficult -

12 
 here are the values of the DDREF for chronic 

13 exposures. 

14 
 DR. TRABALKA: With the percentiles 

15 that are applied in IREP. 

16 
 DR. HOFFMAN: Yes, with the 

17 
 percentiles associated with that distribution. 

18 
 So, at the fifth percentile it can be as 

19 
 small as 0.5. At the 99.5th percentile it can 

20 be as high as 5.0. 

21 
 Now, for chronic exposures, this 

22 
 full distribution is used in IREP. But for 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

19 

1 
 acute exposures, the distribution used is 

2 
 dependent on dose. 

3 
 And so at doses above, let's say, 

4 
 150 milligray, virtually the DDREF is 1.0 or 

5 
 no DDREF at all. 

6 
 But as the acute dose gets less, 

7 
 for example, here we have a small distribution 

8 
 where what we say is the DDREF is uncertain. 

9 
 It varies about 1.0 with a 99 percent range 

10 
 varying from slightly below one up to about 

11 
 1.5. 

12 Now, if we brought the dose to 50 

13 
 milligray or 5 rem, now the distribution 

14 
 increases and it begins to approach that 

15 
 distribution that you would get if you had a 

16 chronic exposure. 

17 
 You get distributions near that for 

18 
 the chronic exposure as you get down towards 

19 10 milligray or 1 rem. 

20 
 MEMBER ZIEMER: Calculationally, is 

21 
 IREP sampling the distribution for each one of 

22 these like it does --

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

20 

1 
 DR. HOFFMAN: The standard run does 

2 
 2,000 iterations. 

3 
 MEMBER ZIEMER: Right. 

4 
 DR. HOFFMAN: And so, there would be 

5 
 2,000 random samples taken from -

6 
 MEMBER ZIEMER: Right. 

7 
 DR. HOFFMAN: - this distribution. 

8 
 So, if you have an acute exposure at 100 

9 
 milligrays, you could sample 2,000 times from 

10 
 this distribution. If you had an acute 

11 
 exposure of 10 milligrays, you would be 

12 sampling 2,000 times from that distribution. 

13 
 MEMBER ZIEMER: And that 

14 
 distribution looks almost normal for 

15 
 everything but breast cancer. I mean, just 

16 
 eyeballing it, it looks kind of log-normal for 

17 the breast cancer. 

18 
 DR. HOFFMAN: Breast cancer and 

19 thyroid cancer -

20 MEMBER ZIEMER: Yes. 

21 
 DR. HOFFMAN: -- where there's a 

22 much heavier weight at 1.0. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

21 

1 
 MEMBER ZIEMER: Correct. 

2 
 MEMBER ROESSLER: So, then go to -

3 
 now, I understand the acute, I think. Now, 

4 
 the chronic is just that last -

5 
 DR. HOFFMAN: Yes. 

6 
 MEMBER ROESSLER: That last part 

7 
 there. 

8 
 DR. HOFFMAN: Right, right. 

9 
 MEMBER ROESSLER: Okay. 

10 
 DR. HOFFMAN: And do we have the 

11 
 distributions for the chronic? Can we go back 

12 to them? 

13 
 Yes. So, that y-axis you had 

14 
 before is just representing these 

15 distributions -

16 
 MEMBER ROESSLER: That's what you 

17 had on the report. 

18 
 DR. HOFFMAN: -- that are used for 

19 
 all solid tumors but breast and thyroid 

20 
 cancer. And as you said, it kind of looks 

21 
 like a normal distribution. And by this, it 

22 looks somewhat like log-normal. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

22 

1 
 MEMBER ROESSLER: Okay. 

2 
 DR. HOFFMAN: But basically that's 

3 
 what's in IREP now. That's not really what's 

4 
 reflected in our updated report. 

5 
 Our updated report is basically a 

6 
 critique of these assumptions. 

7 
 DR. APOSTOAEI: So, we have a 

8 
 figure. This is what we have all the way up. 

9 
 In the figure for acute, we have the 

10 
 distribution on the right. It goes over five. 

11 
 DR. KOCHER: Now, go back to those. 

12 
 Yes, that one. What isn't clear to me on 

13 
 here, I haven't seen this. I've seen a 

14 
 different kind of figure that displays the 

15 same thing. 

16 
 What doesn't come through to me 

17 
 here is about the uncertainty sub L. How is 

18 that folded into these curves? 

19 
 How is the uncertainty sub L 

20 reflected in these curves? 

21 
 DR. HOFFMAN: The D sub L. 

22 
 DR. KOCHER: The acute dose at which 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

23 

1 
 you begin to phase in DDREF is an uncertain 

2 
 variable. 

3 
 DR. HOFFMAN: Right. 

4 
 DR. KOCHER: And so, that has to be 

5 
 somehow reflected in these curves. 

6 
 DR. APOSTOAEI: It's already 

7 
 included. This is what happens. If you type 

8 
 in a dose of 200 milligrays, constant dose, 

9 
 the code will verify that this is greater or 

10 lower than D sub L, it's uncertainty. 

11 
 For each iteration, it will sample 

12 
 a sample of DL, it will compare the dose that 

13 we typed in with that one sample from the DL. 

14 
 DR. KOCHER: The point I'm trying to 

15 
 make is the uncertainty, D sub L, is somehow 

16 already in these curves. 

17 
 DR. APOSTOAEI: The uncertainty is 

18 already -

19 
 DR. KOCHER: Because it's not shown. 

20 (Simultaneous speaking.) 

21 
 MEMBER ZIEMER: So, if I understand 

22 
 what he's saying, so if your dose is - let's 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

24 

1 
 say it's 150, but it has a distribution, so 

2 
 you're sampling around that distribution. 

3 
 And then you're sampling around a -

4 
 doing the same thing. It's like kind of a 

5 
 double iteration, or is it? 

6 
 MR. HOFFMAN: If dose had 

7 
 uncertainty associated with it, yes, you'd be 

8 
 sampling from the uncertainty and dose. But 

9 
 then there's also uncertainty associated with 

10 
 what is the dose that defines a high acute 

11 
 exposure. 

12 
 And so, it's not 200 milligray. 

13 
 It's a distribution ranging from 30 milligray 

14 
 up to -

15 
 MEMBER ZIEMER: That's what I'm 

16 
 saying. But the 30 part of that when you 

17 
 sample it, is going to assign a different -

18 
 DR. HOFFMAN: Right, right. And 

19 
 that uncertainty is reflected in this figure. 

20 
 DR. APOSTOAEI: Yes, that's all 

21 
 taken into account and folded into those 

22 
 figures. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

25 

1 
 DR. KOCHER: If you take 150, 

2 
 there's only a certain - the probability is 

3 
 less than one that you'd apply this correction 

4 
 at all. 

5 
 MEMBER ZIEMER: Right, because the 

6 
 lower ones -

7 
 DR. KOCHER: Because it's now 30. 

8 
 MEMBER ZIEMER: Yes, I got you. And 

9 
 that's how it's doing it in the first one. 

10 DR. HOFFMAN: Yes. 

11 DR. KOCHER: Ready to move on? 

12 MEMBER ZIEMER: Okay. Next one. 

13 
 DR. HOFFMAN: Okay. Now, basically 

14 
 this was the point at which we thought we 

15 
 would stop, because this answers the question 

16 how is DDREF used in IREP. 

17 
 Now, we thought we'd entertain 

18 
 questions from the Board at this point before 

19 
 there is a follow-up discussion in terms of 

20 our report. 

21 
 DR. APOSTOAEI: Or we can continue 

22 the slides. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

26 

1 
 DR. HOFFMAN: It's the Board's 

2 
 choice. 

3 
 MEMBER ZIEMER: Well, you've 

4 
 answered some my questions. 

5 
 MR. KATZ: Any questions on the line 

6 
 from Board Members up to this point? 

7 
 CHAIRMAN RICHARDSON: Well, thank 

8 
 you. It's very useful to kind of start by 

9 
 laying out what's done. And I look forward to 

10 the discussion of the critique of that. 

11 
 One thing I would - since we've 

12 
 given substantial time to this function for 

13 
 phasing in DDREF for acute exposures, I wonder 

14 
 if NIOSH could comment on the proportion of 

15 
 claimants for which an annual dose is - let's 

16 
 start with proportion of claimants if they 

17 
 have some idea of this, where an annual dose 

18 
 would ever be on the magnitude of 200 

19 milligrays. 

20 
 So, this is an annual low-LET 

21 exposure. An external exposure. 

22 
 DR. NETON: This is Jim, Jim Neton. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

27 

1 
 There are some instances of that, but they 

2 
 are few and far between. 

3 
 I would suspect that where they 

4 
 occur is in the very early years of the AEC 

5 
 activities working with the uranium ores, the 

6 
 Belgian Congo ores, that sort of thing. There 

7 
 was a lot of radium in there. I recall at 

8 
 Mallinckrodt we had some pretty high exposures 

9 
 like that. 

10 But outside of that, I think it's 

11 
 unlikely that we would have exposures, acute 

12 exposures in that range. 

13 
 CHAIRMAN RICHARDSON: Okay. But 

14 
 what about, let's take the lower bound of 

15 what's called acute, 30 milligray? 

16 DR. NETON: Same thing. 

17 
 CHAIRMAN RICHARDSON: Because this 

18 
 is my experience in working with Oak Ridge, 

19 
 Hanford, Savannah River, that those are the 

20 magnitudes of career doses. 

21 DR. NETON: Right. 

22 
 CHAIRMAN RICHARDSON: 30 to 50 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

28 

1 
 millisieverts up to maybe a hundred 

2 
 millisieverts or so. 

3 
 But when we're talking about an 

4 
 annual dose, we're not talking about any part 

5 
 of this graph in which there's a phasing going 

6 
 on. We're talking about for, I would imagine, 

7 
 for the vast majority of claimants the doses, 

8 
 an annual dose, is going to be on the 

9 
 magnitude of 10 milligray and below, with 

10 
 those types which actually have relevance to 

11 the claimants that we're considering about. 

12 
 Is that consistent with your kind 

13 
 of interpretation of kind of the bulk of the 

14 claimants in which we're going to be -

15 
 DR. NETON: Yes. Yes, I would agree 

16 with that. 

17 
 DR. KOCHER: Given the limit was 50. 

18 
 DR. NETON: Yes, right. The limit 

19 was 50 for most of those years. 

20 
 CHAIRMAN RICHARDSON: Well, and 

21 
 operationally, I mean, I've encountered very 

22 
 few workers - I mean, there was the 5 rem 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

29 

1 
 study. But, again, that was the 5 rem study 

2 
 of people whose cumulative doses were 5 rem 

3 
 that was conducted for a while by Oak Ridge. 

4 
 DR. NETON: I will say, though, that 

5 
 we do, for the most part, especially the early 

6 
 years, the annual dose is considered to be an 

7 
 acute dose if we can't determine what the 

8 
 individual badge readings were, that sort of 

9 
 thing. 

10 CHAIRMAN RICHARDSON: It's 

11 considered acute. 

12 DR. NETON: Right. 

13 
 CHAIRMAN RICHARDSON: But here it's 

14 
 of such a magnitude that you're back down to 

15 
 the part of the magnitude that once you apply 

16 this factor, it's essentially --

17 DR. NETON: The chronic. 

18 
 CHAIRMAN RICHARDSON: -- getting 

19 
 the weight distribution of the chronic 

20 exposure again. 

21 
 DR. NETON: Exactly. Yes, we do the 

22 
 acute just in case there were high exposures, 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

30 

1 
 you know. We would try to be claimant2 
 favorable, but you're absolutely right. 

3 
 For the most part, it's going to be 

4 
 treated - the acutes for low-LET will be 

5 
 considered principally as if they were --

6 
 well, had a DDREF applied of some magnitude 

7 
 depending on the scale that's used here. 

8 
 That's correct. 

9 
 DR. MAURO: Owen, this is John 

10 
 Mauro. Just a quick question. I don't have 

11 the slide in front of me. 

12 
 Sorry to interrupt, but is any 

13 
 mention made of organ-specific DDREFs, or are 

14 we talking -

15 DR. HOFFMAN: Yes. 

16 
 DR. MAURO: Because I don't have the 

17 
 slide in front of me. 

18 
 DR. HOFFMAN: Yes, if you recall in 

19 
 IREP, John, the DDREF, one, it is not applied 

20 
 for leukemias. We have a different 

21 
 distribution for breast and thyroid than we 

22 have for all other solid tumors. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

31 

1 
 DR. MAURO: Okay. I'm sorry I missed 

2 
 that. Thank you for your answer. 

3 
 DR. HOFFMAN: Yes. 

4 
 DR. MAURO: And the only reason it 

5 
 triggered my question was when we were talking 

6 
 about what the doses are and we talk about 1 

7 
 rem per year, often some organs do get some 

8 
 fairly high doses. Especially the respiratory 

9 
 tract. And that triggered that question. 

10 DR. HOFFMAN: Sure. 

11 
 DR. NETON: But there, John, you 

12 
 were principally talking, I think, about alpha 

13 emitters. 

14 
 DR. MAURO: That's true. You're 

15 absolutely right. You're absolutely right. 

16 (Simultaneous speaking.) 

17 
 DR. NETON: That's another issue 

18 that I'm sure we'll get into. 

19 DR. MAURO: Yes, yes. 

20 
 DR. NETON: The DDREF actually does 

21 
 get applied to high-LET alpha emitters in a 

22 sort of different way. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

32 

1 
 DR. TRABALKA: As a part of the 

2 
 correction for radiation effectiveness factor 

3 
 for alphas, but there's also an inverse dose4 
 rate effect that more than outweighs that. 

5 
 So, it's a complicated picture. 

6 
 DR. NETON: Yes, it is. 

7 
 MEMBER MUNN: As most of this is. 

8 
 DR. TRABALKA: Yes. Yes, it is. 

9 
 MR. KATZ: Is that it for questions 

10 on the line? 

11 
 CHAIRMAN RICHARDSON: One other 

12 
 thing I'd like to just point out is there was 

13 
 some discussion about the symmetry of the 

14 
 distribution for cancers other than breast and 

15 
 thyroid. And I heard some comments, but I'm 

16 not sure if it was clear. 

17 
 That apparent symmetry, I guess, is 

18 
 - it was noted the distribution looks normal, 

19 
 but it's looking normal on an arithmetic 

20 scale, but it's a ratio measure. 

21 
 So, a value of 0.5, if there was 

22 
 going to be actual symmetry here, would be 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

33 

1 
 bounded against the value of two, for example. 

2 
 So, if the DDREF was 0.5, that 

3 
 would say it was half as effective. And if 

4 
 it's two, it would say it was - or vice-versa. 

5 
 Twice as effective and half as effective. 

6 
 So, here it's actually, when it's 

7 
 going out to values of five and down to values 

8 
 of 0.5, that's - I would mentally imagine that 

9 
 as very skewed in one direction. 

10 
 MEMBER ZIEMER: You're right, David. 

11 
 As I look at these, these are not linear 

12 
 scales depicted here. They are just numbers. 

13 
 It's a bar graph you're looking at, as I see 

14 it. 

15 
 I was glancing at it and it looked 

16 
 like that, but I realize now that they are not 

17 really linear. 

18 CHAIRMAN RICHARDSON: Right. 

19 
 MEMBER ZIEMER: Although having said 

20 
 that, if you look at the actual values, I 

21 
 think the breast and lung still probably is 

22 
 very skewed toward one. So, probably logNEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

34 

1 
 normal. 

2 
 I mean, the 0.5 and 0.7 are spread 

3 
 out. 

4 
 DR. KOCHER: Don't put a great deal 

5 
 into particular percentiles on these numbers. 

6 
 CHAIRMAN RICHARDSON: Oh, I'm not, 

7 
 but I'm just thinking about the issue of: is 

8 
 it symmetrical around a value? 

9 
 And it's - I would say it's not, 

10 
 right? It's going towards dose-rate 

11 
 effectiveness factors which you would divide 

12 
 the risk coefficients by a factor of two, 

13 
 three, four or five, and the low probability 

14 
 that you're going to divide it by a value of 

15 
 0.7 or 0.5, but you would never go down to a 

16 
 value like 0.2, which would be symmetrical 

17 around five. 

18 
 MEMBER ZIEMER: Well, but that may 

19 
 raise the question: does IREP put this in as a 

20 distribution, or as a number of points? 

21 
 DR. HOFFMAN: It's a discrete 

22 distribution, exactly as you see it here. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

35 

1 
 MEMBER ZIEMER: What we see here. 

2 
 DR. HOFFMAN: And so, I mean, these 

3 
 distributions originally were derived by Ethel 

4 
 Gilbert. And there was no attempt to make one 

5 
 log-normal, normal or - it was degrees of 

6 
 belief based on her review of the literature 

7 
 that would be put on discrete values. 

8 
 Does that help, David? 

9 
 CHAIRMAN RICHARDSON: Yes, thank 

10 
 you. 

11 
 DR. HOFFMAN: Okay. 

12 
 DR. KOCHER: You can still have 

13 
 symmetry about values other than one. One is 

14 
 not the midpoint of anything. It can be 

15 
 symmetric around two. 

16 
 DR. HOFFMAN: Well, we are prepared 

17 
 now to continue to change the focus of the 

18 
 discussion into a summary of where we are with 

19 
 respect to our draft - this is a major report. 

20 
 A major draft report on the state of 

21 
 knowledge of DDREF. Probably the most 

22 
 extensive report of its kind anywhere. The 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

36 

1 
 only problem is it's not published. It's 

2 
 still in draft form. 

3 
 But I'd like to say that John 

4 
 Trabalka of our staff is taking the lead on 

5 
 this work. This is the work now that probably 

6 
 spans six, seven years in the making. 

7 
 And so, I'd like John to continue 

8 
 with the presentation. 

9 
 DR. TRABALKA: I will. I'll add one 

10 thing to what Owen just said. 

11 
 At least one member of the ICRP 

12 
 team that was going to develop or at least 

13 
 review the concept of DDREF, expressed the 

14 
 hope to me that our report would be out before 

15 
 theirs was even started so they wouldn't have 

16 
 to do the review and evaluation. They could 

17 just critique ours and use as much. 

18 
 It's so much easier to critique 

19 somebody else's work than to do it yourself. 

20 MEMBER MUNN: Always easier. 

21 
 DR. TRABALKA: Okay. Let's go ahead 

22 
 and talk about where the information for 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

37 

1 
 estimating the DDREF comes from. Go ahead, 

2 
 the first part. 

3 
 Now, there is information from 

4 
 genetic and cytogenetic endpoints that's used 

5 
 in estimating DDREF - you just jumped ahead to 

6 
 - go back, back, back. First one. 

7 
 Okay. There is information, as I 

8 
 said, for these other endpoints, but I am 

9 
 going to focus on information that's obtained 

10 
 from laboratory animals and humans for 

11 potentially estimating DDREFs. 

12 
 Much of that information should be 

13 
 characterized as representing low-dose 

14 extrapolation factors. 

15 
 You can obtain estimates of the 

16 
 relative effectiveness of low acute doses, for 

17 
 example, by analyzing the curvature in dose 

18 
 responses for acute exposures like cancer in 

19 the A-bomb survivors. 

20 
 And that's been done very heavily. 

21 
 There's a lot of data. And in our report, we 

22 
 document all of the values that have been 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

38 

1 
 published on that. 

2 
 You can also estimate it from --

3 
 cancer responses from fractionated exposures 

4 
 like from medically irradiated humans. 

5 
 Compare those, for example, with responses in 

6 
 the A-bomb survivors to estimate it, and in 

7 
 laboratory animals where you look at the 

8 
 curvature in the dose response for acute 

9 
 exposures. 

10 
 Let's continue on to the next one. 

11 
 Also, much of the literature and many of the 

12 
 values are best characterized as dose-rate 

13 
 effectiveness factors, because they compare 

14 
 relative effectiveness of low-dose rates with 

15 
 those at high-dose rates. 

16 
 Examples are the epidemiological 

17 
 studies of radiation workers compared to the 

18 
 A-bomb survivors, persons exposed in 

19 
 environmental or medical settings - an example 

20 
 of the environmental settings would be folks 

21 
 who were exposed along the Techa River in 

22 
 Russia. Medical settings, the Swedish skin 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

39 

1 
 hemangioma cohorts; these were children who 

2 
 were given exposures with radium applicators 

3 
 because they had blotches on their skin, and 

4 
 of course had developed all sorts of cancers 

5 
 afterwards - and also studies of cancer in 

6 
 laboratory animals. 

7 
 These particular studies were the 

8 
 ones that were used by the NCRP and also by 

9 
 UNSCEAR in its 1993 report, and were used as 

10 
 part of the basis for the DDREF of two that 

11 was selected by the ICRP, for example. 

12 
 But because of theoretical 

13 
 considerations, when you get down to low doses 

14 
 and dose rates and assuming a linear quadratic 

15 
 model as the basis, which does not always 

16 
 work, and there are a lot of data suggesting 

17 
 the linear quadratic model is not always 

18 
 applicable, nonetheless, when you do that, the 

19 
 two values should converge. The LDEFs and the 

20 
 DREFs should be the same. So, we typically 

21 
 use the term DDREF or a dose and dose-rate 

22 effectiveness factor. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

40 

1 
 Any questions on this before we 

2 
 move on? 

3 
 CHAIRMAN RICHARDSON: I have one 

4 
 question. 

5 
 I thought I understood what you 

6 
 meant by LDEF until you suggested that cancer 

7 
 from fractionated exposures compared to an 

8 
 acute exposure -

9 
 DR. TRABALKA: Fractionated acute 

10 
 exposures. 

11 
 CHAIRMAN RICHARDSON: So, you're 

12 
 making a distinction between - so, you're 

13 
 saying for the same total dose if it's 

14 
 fractionated - I would imagine if it's 

15 
 fractionated or protracted, for the same total 

16 
 dose deposited, that that would be - that you 

17 
 would, for the distinctions in effect as those 

18 
 being dose-rate effects. 

19 
 Why is that? 

20 
 DR. TRABALKA: Iulian and I have had 

21 
 that discussion. And Iulian would agree with 

22 
 you. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

41 

1 
 I simply make the point that these 

2 
 are data from fractionated acute exposures as 

3 
 opposed to data from chronic exposures, 

4 
 continuous exposures. 

5 
 I would agree that that's a moot 

6 
 point. 

7 
 MEMBER ZIEMER: And fractionated 

8 
 acute in this case, you're still using the 200 

9 
 millisievert as something above that as being 

10 
 -

11 
 DR. TRABALKA: No, no, no. These 

12 
 acute exposures, for example -

13 
 MEMBER ZIEMER: When a medical 

14 
 exposure is really high? 

15 
 DR. TRABALKA: For example, you 

16 
 know, rats. Exposures to look at mammary 

17 
 cancer in rats. They used acute exposures 

18 
 separated in time by 12 or 24 hours. 

19 
 MEMBER ZIEMER: Yes. 

20 
 DR. TRABALKA: And down around, say, 

21 
 four milligray, ten milligray, all the way up 

22 
 to maybe a hundred milligray. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

42 

1 
 MEMBER ZIEMER: Right. 

2 
 DR. TRABALKA: So, there's a wide 

3 
 range of doses and exposure conditions. 

4 
 MEMBER ROESSLER: So, to continue on 

5 
 that - this is a good discussion, I think. 

6 
 But in the top category, the medically 

7 
 irradiated humans, they're the ones who are 

8 
 treated for something and they're actually 

9 
 fractionated. 

10 Then when you go down to the 

11 
 second, the DREF, and you talk about medical 

12 
 settings, are you talking about occupational 

13 exposures there? 

14 
 DR. TRABALKA: No, the example I 

15 
 used was the Swedish skin hemangioma cohorts. 

16 
 That was a medical exposure, but what they 

17 
 did is: they put an applicator on a blotch on 

18 the skin and left it there for several hours. 

19 
 MEMBER ROESSLER: I get it. I 

20 missed that, yes. 

21 
 DR. KOCHER: But the doses are well 

22 known. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

43 

1 
 DR. TRABALKA: Yes, reasonably well 

2 
 known or estimated, I should say. 

3 
 Ready to move on? 

4 
 MEMBER ZIEMER: Yes. 

5 
 DR. TRABALKA: Well, I suppose most 

6 
 of us realize why reevaluating DDREFs is 

7 
 important. 

8 
 The ones used in IREP have a great 

9 
 deal of subjectivity. There has been a lot of 

10 
 information published since IREP was 

11 developed. 

12 
 There are now useful studies of 

13 
 nuclear workers that bear on this issue, some 

14 
 research in the DOE low-dose program. So, 

15 
 reassessing the magnitude and uncertainty of 

16 DDREF is important. 

17 
 And the underlying basis, the LNT 

18 
 model, is heavily challenged. I mean, let's 

19 
 face it. There's a large fraction of the 

20 community out there that does not accept it. 

21 
 There's a wide range of alternative 

22 
 information, also, for developing an improved 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

44 

1 
 basis. 

2 
 So, our objective is to try and 

3 
 reduce the level of subjectivity, provide 

4 
 better traceability for the information and 

5 
 improve the documentation. 

6 
 Any questions on that? 

7 
 CHAIRMAN RICHARDSON: Can you 

8 
 clarify the distinction you're making here 

9 
 between the underlying basis of a linear and a 

10 
 threshold model and your assumption of a 

11 
 linear quadratic model, which you said is your 

12 starting point? 

13 
 DR. TRABALKA: At low doses, the 

14 
 linear quadratic model defaults to a linear 

15 no-threshold model. 

16 
 But the basis for a DDREF is based 

17 
 on the assumption that a linear quadratic 

18 
 model over the entire dose range of your 

19 
 epidemiological information is the proper way 

20 to go about calculating it. 

21 
 CHAIRMAN RICHARDSON: And, see, I've 

22 never encountered that, I guess. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

45 

1 
 DR. TRABALKA: I'm afraid that is 

2 
 the basis, however, for DDREF. It's discussed 

3 
 in Section 2 of the report in detail. 

4 
 In fact, probably a linear 

5 
 quadratic exponential model fits much of the 

6 
 data better than just a plain linear quadratic 

7 
 model. 

8 
 Let's not get into that. I'd 

9 
 rather have you read it. I'll be happy to 

10 answer any questions you have about it. 

11 
 CHAIRMAN RICHARDSON: No, I have 

12 
 read your report, but I guess I'm asking for 

13 
 some coherence between the assertion and what 

14 
 I encounter as how epidemiologic data are 

15 modeled in radiation epidemiology. 

16 
 One doesn't start out with a 

17 
 parametric form and fit it to the data 

18 
 regardless of whether it conforms well to the 

19 data. 

20 
 And typically, you would not 

21 
 saturate a model by including kind of 

22 
 polynomial functions if a simpler model fitted 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

46 

1 
 it. 

2 
 DR. TRABALKA: Well, I agree with 

3 
 that. But if you look at how DDREF, for 

4 
 example, has been estimated from the Japanese 

5 
 A-bomb survivor data, it's based on curvature 

6 
 assuming a linear quadratic model or by 

7 
 comparing risk coefficients from the linear 

8 
 model versus the linear risk coefficient from 

9 
 a linear quadratic model. 

10 
 That's how the data are obtained if 

11 you have an acute exposure, for example. 

12 
 CHAIRMAN RICHARDSON: No, I don't 

13 think that's right, actually. 

14 DR. TRABALKA: I'm afraid it is. 

15 
 CHAIRMAN RICHARDSON: But, I mean, 

16 
 we can go on. 

17 DR. TRABALKA: Okay. 

18 
 CHAIRMAN RICHARDSON: I mean, none 

19 
 of the DDREF values that would be shown in 

20 
 this distribution for solid cancers would be -

21 
 I think you would say that the basis for any 

22 
 of these bars in this histogram are the ratio 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

47 

1 
 of the quadratic to the linear term for solid 

2 
 cancers in the A-bomb data. Values two, 

3 
 three, four, five, right? 

4 
 I mean, there's curvature for the 

5 
 leukemias, but we've set that aside. 

6 
 DR. TRABALKA: The basis for those 

7 
 values in the current version of IREP came 

8 
 from data all over the map. 

9 
 CHAIRMAN RICHARDSON: Yes, exactly. 

10 
 DR. TRABALKA: It was highly 

11 
 subjective. But if you look in - if you read 

12 
 Section 4 and particularly Section 4.2, look 

13 
 at the Japanese A-bomb survivor DDREFs and you 

14 
 look at how those were derived, you'll see the 

15 
 linear quadratic model or a linear quadratic 

16 
 exponential model was used to derive those 

17 DDREFs. 

18 
 When you get to cancers like breast 

19 
 cancer, thyroid cancer, you have to compare 

20 
 responses in those cohorts to the linear risk 

21 
 - in other words, the linear risk coefficients 

22 
 from those studies to linear risk coefficients 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

48 

1 
 derived from the A-bomb survivor studies, 

2 
 because you don't have the acute exposure 

3 
 component. 

4 
 You don't have a linear quadratic -

5 
 enough information to do a linear quadratic 

6 
 dose response. And it would be questionable 

7 
 to use it there anyway. 

8 
 And if you look at some of the 

9 
 other cancers, that's also true for the lung, 

10 
 bone and skin cancer. You have to compare it 

11 
 typically with - in other words, linear risk 

12 
 coefficients in one case, and quadratic 

13 
 coefficients - or linear coefficients from 

14 
 linear quadratic responses, or just linear 

15 
 coefficients from the A-bomb survivors with 

16 
 those linear coefficients. 

17 When you look at skin cancer -

18 
 CHAIRMAN RICHARDSON: Exactly. The 

19 last one is, I think, was done in practice. 

20 
 DR. TRABALKA: Yes, and we've done 

21 that in a lot of cases in the report. 

22 
 If you look, however, at the data 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

49 

1 
 for skin cancer, especially that in the latest 

2 
 iteration, the DSO dose response by Preston 

3 
 and company, they use what's called a linear 

4 
 spline model. Which is a straight line 

5 
 linear, in other words, a linear response at 

6 
 low doses compared to a linear response at 

7 
 higher doses, and you have to take the ratio 

8 
 of those two to get a DDREF. 

9 
 And you get a different value 

10 
 estimated for DDREF when you do that. It's 

11 
 about six, as opposed to one to two from most 

12 of the data for the A-bomb survivors. 

13 
 I hope that also explains or helps 

14 
 answer the question about whether or not we're 

15 
 looking at cancers other than - in addition to 

16 breast and thyroid cancer in our effort here. 

17 Should we go on, David? 

18 CHAIRMAN RICHARDSON: Yes, please. 

19 
 DR. TRABALKA: Okay. All right. 

20 Let's go on to the next one. 

21 
 So, in our review, we looked at the 

22 
 existing and new classical information. By 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

50 

1 
 "classical," we mean epidemiological, 

2 
 radiobiological, micro-dosimetric data and 

3 
 concepts. 

4 
 Examples are the new radiation 

5 
 worker studies and what their implications are 

6 
 for DDREF, the DSO2 base dose response for the 

7 
 A-bomb survivors. 

8 
 But we also felt we had to look at 

9 
 emerging information on other phenomena, 

10 
 because there is such a large part of the 

11 
 community that's pretty adamant that these 

12 need to be considered in dose responses. 

13 
 And these include adaptive 

14 
 responses, bystander effects, induced genomic 

15 
 instabilities, low-dose hyper16 
 radiosensitivity, existence of thresholds and 

17 hormetic responses. 

18 Any questions on that? 

19 
 MEMBER ZIEMER: I have one question, 

20 
 because it's fascinated me and has to do with 

21 the bystander. 

22 
 Is a bystander cell right adjacent 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

51 

1 
 to a cell that is, let's say, hit? I'll use 

2 
 the word "hit." Or could it be somewhere 

3 
 else? 

4 
 How far removed can a bystander be? 

5 
 I mean, we have in the body, situations where 

6 
 something far removed from a location that's 

7 
 called on to assist a cell. 

8 
 Maybe the, I don't know, some organ 

9 
 is called on to release something because a 

10 cell has -

11 
 DR. HOFFMAN: Okay. In other words, 

12 
 what's the distinction between bystander 

13 effects and abscopal effects? 

14 MEMBER ZIEMER: Well -

15 
 DR. HOFFMAN: Abscopal effects is 

16 
 one part of the body is irradiated, but 

17 
 another part of the body expresses the cancer. 

18 
 MEMBER ZIEMER: That's exactly my 

19 question, because it has great implication -

20 DR. HOFFMAN: Yes. 

21 
 MEMBER ZIEMER: We use, in this 

22 
 program, the organ. We take the energy 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

52 

1 
 delivered to that organ as being sort of a 

2 
 cause and effect situation. 

3 
 And so, it's never been clear to me 

4 
 on bystander, how far away is the bystander? 

5 
 It's sort of what you raised earlier. 

6 
 Like I'm hitting the line and is my 

7 
 finger is going to suffer for that? I mean, I 

8 
 would think intuitively it's pretty close by, 

9 
 but -

10 DR. TRABALKA: The tissue models 

11 
 that have been used to study bystander effect 

12 
 suggests that we're talking about distances of 

13 millimeters to a centimeter or two. 

14 
 However, as Owen pointed out, there 

15 
 are - there is evidence of abscopal effects 

16 especially in animals. 

17 
 MEMBER ZIEMER: And what does that 

18 word mean, exactly? 

19 
 DR. TRABALKA: Well, for example, 

20 
 you irradiate the leg of a certain species or 

21 
 strain of rat and it develops mammary cancer. 

22 
 You irradiate the leg of a mouse and it 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

53 

1 
 develops - what's the word I'm looking for 

2 
 here? A kind of lymphoma. Thymic lymphoma. 

3 
 MEMBER ZIEMER: Yes. 

4 
 DR. TRABALKA: Albrecht Kellerer has 

5 
 suggested that we have to be very cautious 

6 
 about the Techa River data, because the doses 

7 
 to bone marrow were so high that he suggests 

8 
 that abscopal effects on the rest of the body 

9 
 could be influencing the dose responses in 

10 those people. 

11 
 Some of those folks were thought to 

12 
 have had chronic radiation sickness from 

13 exposures. These are extremely high doses. 

14 MEMBER ZIEMER: Yes. 

15 
 DR. TRABALKA: Especially those 

16 
 closest to the fuel reprocessing plant and the 

17 high-level waste storage tanks. 

18 Does that answer your question? 

19 
 MEMBER ZIEMER: Yes, I just wanted 

20 
 to get a feel for it. It could be, in 

21 principle, fairly extensive then. 

22 
 DR. KOCHER: The problem here, of 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

54 

1 
 course, is that our basic data set is uniform 

2 
 whole-body irradiation. 

3 
 MEMBER ZIEMER: Right. 

4 
 DR. KOCHER: So, if these effects 

5 
 are real, they're buried in there somewhere. 

6 
 MEMBER ZIEMER: They're buried in 

7 
 there. 

8 
 DR. KOCHER: And you don't know how 

9 
 to adapt that to partial body exposures, if 

10 you think there's a difference. 

11 MEMBER ZIEMER: Exactly. Exactly. 

12 
 DR. TRABALKA: Let me conclude this 

13 
 slide by saying that there is no consensus 

14 
 currently on whether these phenomena really 

15 
 influence epidemiological data. In some 

16 
 cases, they are thought to be embedded in 

17 current epidemiologic data. 

18 
 MEMBER ZIEMER: I understood from 

19 
 your report, at least I thought I understood 

20 
 on the hormetic, you or someone was suggesting 

21 
 that that might even have lower and upper 

22 bounds. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

 

55 

1 
 DR. TRABALKA: That's right. 

2 
 MEMBER ZIEMER: And below, it may 

3 
 not exist. 

4 
 DR. TRABALKA: The more recent 

5 
 studies show that although you might see a 

6 
 threshold effect at one dose or dose rate or a 

7 
 potential for hormetic effect, that at lower 

8 
 doses you actually see an increased effect. 

9 
 You have to be very cautious about 

10 
 interpreting that information, especially as 

11 it applies to humans. 

12 
 MEMBER ZIEMER: And it could be very 

13 dependant on the endpoint in either case. 

14 
 DR. TRABALKA: Very much so. And 

15 
 so, the precautionary principle has to apply 

16 there. We have to use the linear approach. 

17 
 MEMBER ZIEMER: Right now it seems 

18 
 to me, although it's interesting to look at 

19 
 all of these, on most of them we're pretty far 

20 away from knowing answers; is that correct? 

21 DR. TRABALKA: That's correct. 

22 
 MEMBER ZIEMER: Okay. Well, we can 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

56 

1 
 leave that. 

2 
 DR. TRABALKA: Yes. 

3 
 MEMBER ROESSLER: As I look at this 

4 
 slide and the things you're talking about, 

5 
 especially the emerging information, this is a 

6 
 huge amount of data. 

7 
 I've been to NCRP meetings where 

8 
 they talk about all this stuff and it is new. 

9 
 It just seems like this is a huge amount of 

10 
 work that nobody else is really doing that 

11 
 you've done, and you've put in a number of 

12 years on this. 

13 
 So, my question is, who's funding 

14 it and where will it be published? 

15 
 DR. TRABALKA: It's in our report in 

16 Appendix B of our report. 

17 MEMBER ROESSLER: Okay. 

18 DR. TRABALKA: And in Section 3. 

19 
 DR. HOFFMAN: And the answer is, 

20 
 NIOSH is funding this effort. And when and 

21 
 where will it be published is partly at the 

22 discretion of NIOSH. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

57 

1 
 DR. NETON: In the TBD. 

2 
 MEMBER ZIEMER: But you're funding 

3 
 the pulling together of the information, the 

4 
 research itself. 

5 
 DR. HOFFMAN: Yes, but we recognize, 

6 
 I mean, we have the pleasure and honor of 

7 
 being charged with doing this work and it's 

8 
 put us at the forefront of the group. 

9 
 MEMBER ROESSLER: This is a huge 

10 
 contribution that is being made to this 

11 
 program. 

12 
 I think one of the early ones was 

13 
 David's work on REF. It was published. 

14 
 There's a lot that's been published. 

15 
 This is something very 

16 
 scientifically important to be doing this. 

17 
 MEMBER MUNN: It is. 

18 
 DR. TRABALKA: Ready to move on? 

19 
 GROUP RESPONSE: Yes. 

20 
 DR. TRABALKA: Okay. I just want to 

21 
 briefly touch on information on DDREFs that we 

22 
 can obtain from the genetic and cytogenetic 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

58 

1 
 endpoints like cell transformation, chromosome 

2 
 aberrations or point mutations. 

3 
 The range of values is quite large, 

4 
 typically in the one to 12 range, but also 

5 
 values much less than one of infinity are out 

6 
 there from threshold or potential hormetic 

7 
 responses that are shown in the literature. 

8 
 The central estimates are around two to six. 

9 
 These dose responses are complex, 

10 
 often difficult to interpret, and they 

11 
 represent only one of the many steps that is 

12 
 required to take a radiation-induced lesion up 

13 
 to a cancer. So, you have to interpret these 

14 with a grain of salt. 

15 
 There was some information early on 

16 
 suggesting that the DDREFs might be LET17 
 dependent for endpoints like chromosome 

18 
 aberrations and cell transformation suggesting 

19 
 that they might decrease with decreasing 

20 
 photon energy, for example, but more recent 

21 
 information suggests that that probably is not 

22 an issue. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

59 

1 
 It is, however, still an issue for 

2 
 RBEs and radiation effectiveness factors. In 

3 
 fact, this is still, in other words, the 

4 
 suggestion that for photon energy you might 

5 
 have - when it decreases, you might have an 

6 
 increase in RBE. 

7 
 That is the subject of a current 

8 
 NCRP Committee effort that David is involved 

9 
 in. And so, whatever results from that 

10 
 committee effort, assuming it comes out before 

11 
 our report gets out, we will factor into our 

12 report at some future date. 

13 Okay. Shall we move on? 

14 
 This rather busy slide is a summary 

15 
 of the animal data. Most of it is animal 

16 
 cancer data. 

17 There is one data point at the 

18 
 bottom for mice for life shortening. And the 

19 
 reason there's only one is that life 

20 
 shortening typically doesn't - data don't 

21 
 typically distinguish between leukemias and 

22 lymphomas and solid cancers. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

60 

1 
 This particular set of data on mice 

2 
 does that, and you get a DREF of about one 

3 
 from that data set. 

4 
 The other data come from - in one 

5 
 case, there are combined malignancies, mammary 

6 
 cancer in mice and rats, lung cancer in mice, 

7 
 beagle dogs, non-melanoma skin cancer in mice. 

8 
 A number of these endpoints have 

9 
 infinity either as the best estimate or the 

10 
 upper bound, because they represent potential 

11 threshold data. 

12 
 These show up typically when you 

13 
 get exposures to single organs like the lung 

14 or the bone. 

15 
 A lot of the bone data comes from 

16 
 exposures to animals from strontium-90, for 

17 example. 

18 
 There are also some data on 

19 
 pituitary tumors. Harderian gland, for some 

20 
 reason harderian gland DDREFs have been 

21 fascinating for some of the radiologists. 

22 
 But for us, they're not 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

61 

1 
 particularly useful because they only occur in 

2 
 animals with a third eyelid. And since none 

3 
 of us seem to have third eyelids, they're not 

4 
 typically useful. 

5 
 If you look at the data, most of 

6 
 the values, most of the point estimates range 

7 
 from about one to ten. Actually, most of them 

8 
 fall between one and six, except for the 

9 
 threshold data. 

10 
 And we've attempted to estimate 

11 
 what the lower bounds for DDREF might be on 

12 
 some of this threshold data, and we typically 

13 get values between ten and 20. 

14 
 And other investigators who have 

15 
 used alternate models for that same data, come 

16 
 out with values on the order of, say, 20 or 

17 
 more. So, we think we're in the right 

18 ballpark. 

19 
 In other words, despite the fact 

20 
 that there are what appear to be apparent 

21 
 thresholds in this data, there could very well 

22 
 be concealed linear quadratic responses in 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

62 

1 
 these data that still have a finite, but quite 

2 
 large DDREF. 

3 
 And what it really suggests is that 

4 
 for bone cancer, the linear risk coefficient 

5 
 could be much lower than it is for carcinomas 

6 
 and other cancers. 

7 
 Okay. Any questions on this before 

8 
 we go on? 

9 
 MEMBER ROESSLER: What are Long10 Evans rats? 

11 
 DR. TRABALKA: Just a strain of rat 

12 that's favored in some research. 

13 
 MEMBER ROESSLER: They just kind of 

14 fall out of the picture here. 

15 
 DR. TRABALKA: Well, these were used 

16 
 in a study comparing the effects of x-rays, 

17 localized x-rays and iodine-131. 

18 
 And if you assume that there is no 

19 
 higher effectiveness for x-rays, the value 

20 moves up to about double, about 1.2. 

21 
 If you use the information that 

22 
 suggests that the radiation effectiveness - or 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

63 

1 
 the RBE for x-rays should be about twice that 

2 
 for iodine-131 beta and gamma radiation, you 

3 
 get a value of 0.6, but the uncertainties are 

4 
 great enough in that information that still 

5 
 overlaps one and the upper bound is close to 

6 
 two. 

7 
 These are mostly 95 percent 

8 
 confidence intervals, but some represent 

9 
 ranges of data. 

10 
 Where there are bars on the end of 

11 
 the lines, those represent confidence 

12 
 intervals. The rest of them are ranges. For 

13 
 example, data in mice and rats on mammary 

14 
 cancer typically fall between two and three. 

15 Something like that. 

16 Should we move on? 

17 
 MEMBER ZIEMER: The life shortening 

18 
 on this particular one, there's no bars there. 

19 DR. TRABALKA: No. 

20 
 MEMBER ZIEMER: What did you say 

21 about that? 

22 
 DR. TRABALKA: The information to 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

64 

1 
 provide uncertainties in that data isn't 

2 
 available. 

3 
 This is based on work that was done 

4 
 at Argonne National Laboratory in the pre5 
 JANUS studies over a significant period of 

6 
 time. 

7 
 The dose rates in this set of 

8 
 studies extend down to 0.002 milligray per 

9 
 minute, which is 50 times lower than the dose 

10 
 rate at which a chronic DDREF is applied in 

11 
 IREP, and significant life shortening was 

12 being observed even at that lowest dose rate. 

13 
 And of course it didn't go any 

14 
 further, but still it was linear down to that 

15 range. 

16 
 MEMBER ZIEMER: Significant life 

17 
 shortening at low dose rates but high total 

18 doses? 

19 
 DR. TRABALKA: Well, at 0.002, it 

20 
 would be over the entire life of the mouse. 

21 
 So, we're talking probably several hundred 

22 days in this case. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

65 

1 
 We have to convert that to per day 

2 
 and -

3 
 MEMBER ZIEMER: In my memory bank 

4 
 somewhere, there are some mice studies where 

5 
 you actually get lifespan increases -

6 
 DR. TRABALKA: Oh, yes. 

7 
 MEMBER ZIEMER: -- because of the 

8 
 fact that the mother mice have, at higher 

9 
 doses, have smaller litters. And that's less 

10 
 wear and tear on the mice and they live 

11 longer. 

12 
 DR. TRABALKA: That issue is 

13 
 discussed in Section 4.3 of our report. You 

14 
 have to be kind of careful about how you 

15 interpret these apparent beneficial effects. 

16 MEMBER ZIEMER: Exactly. 

17 
 DR. TRABALKA: If you look at the 

18 
 one case that you mentioned, the study by 

19 
 Storer and his colleagues at Oak Ridge 

20 
 National Laboratory, it used the largest 

21 
 number of mice in any study on life 

22 shortening. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

66 

1 
 And they still saw between two sets 

2 
 of controls, a 30-day difference in lifespan, 

3 
 which is on the order of what's typically 

4 
 observed in these studies that show apparent 

5 
 lifespan increases, and that's just in 

6 
 controlled. 

7 
 It simply shows that in animal 

8 
 studies or any kind of research, you can have 

9 
 variations in your controls that are hard to 

10 explain. 

11 MEMBER ZIEMER: Yes. 

12 
 DR. TRABALKA: You've got to be very 

13 
 cautious about how you interpret that data as, 

14 
 for example, representing a real effect on 

15 lifespan increases or something like that. 

16 Shall we proceed? 

17 
 MEMBER ZIEMER: And that's just an 

18 
 animals where you - they're all alike. Can't 

19 go to humans. 

20 
 DR. KOCHER: John, is this kind of 

21 
 information that UNSCEAR used to come up with 

22 their two to ten range back in the day? 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

67 

1 
 DR. TRABALKA: The NCRP. Most of it 

2 
 is what NCRP used. Not all of it, because not 

3 
 all of it was available. 

4 
 NCRP came up with the two to ten 

5 
 range, but ICRP came up with their DDREF of 

6 
 two. 

7 
 They used the lower end of the 

8 
 range of animal data, because it was more 

9 
 consistent with what they thought the A-bomb 

10 survivor dose-rate response represented. 

11 
 CHAIRMAN RICHARDSON: I have a 

12 couple questions, if I could. 

13 DR. TRABALKA: Sure. Yes. 

14 
 CHAIRMAN RICHARDSON: The first one 

15 
 was just an issue of understanding the 

16 presentation of the data. 

17 
 The scale on - the X scale. I was 

18 
 imagining, if you would move to the right from 

19 one, that that next line represents two. 

20 DR. TRABALKA: That's correct. 

21 
 CHAIRMAN RICHARDSON: And that if 

22 
 you move to the left from one, you're moving 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

68 

1 
 to 0.9; is that correct? 

2 
 DR. TRABALKA: That's correct. It's 

3 
 a log scale. 

4 
 DR. HOFFMAN: So, you have 

5 
 arithmetic numbers on log scale. 

6 
 DR. KOCHER: I think his point is 

7 
 there's a few ticks missing. 

8 
 CHAIRMAN RICHARDSON: I'm trying to 

9 
 find what's balanced. Where would you get -

10 
 MEMBER ZIEMER: I think the nine is 

11 at the edge of the green. 

12 MEMBER ROESSLER: The blue line. 

13 (Simultaneous speaking.) 

14 
 CHAIRMAN RICHARDSON: Okay. So, I'm 

15 
 sort of understanding it. Just maybe there's 

16 - it's not easy to see. Is that the -

17 
 DR. TRABALKA: A very complicated 

18 data set. 

19 
 DR. HOFFMAN: Yes, but it's a log 

20 scale and so all the ticks should be there. 

21 
 CHAIRMAN RICHARDSON: Okay. But the 

22 
 experimental design for the - there's one 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

69 

1 
 circle - well, there's two circles. 

2 
 I'm trying to imagine an 

3 
 experimental dosing design that conforms to 

4 
 DDREF as opposed to the other two categories 

5 
 you have there. 

6 
 I can imagine an experiment in 

7 
 which we apply an acute dose to animals of 

8 
 different magnitudes and we study the shape of 

9 
 the dose response with an acute exposure. 

10 
 And I can imagine a dosing 

11 
 experiment in which we aim to deliver to the 

12 
 animal the same total dose, but under 

13 different periods of protraction. 

14 
 What's the experimental design that 

15 conforms to the DDREF? 

16 
 DR. TRABALKA: Actually, I think 

17 
 that symbol should be a square, because these 

18 
 were continuous exposures at varying dose 

19 
 rates. We just have the wrong symbol up 

20 there. 

21 
 MEMBER ROESSLER: So, you switch the 

22 DDREF and the DREF? 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

70 

1 
 DR. TRABALKA: No, no. On the life 

2 
 shortening data point for the square. 

3 
 MEMBER ROESSLER: Well, within the 

4 
 figure there's around -

5 
 DR. TRABALKA: Oh, okay. The reason 

6 
 why the DDREF is shown for lung is that when 

7 
 they - this particular data set they were able 

8 
 to fit to a linear quadratic model and to show 

9 
 that you got the same answer as you would get 

10 
 if you were giving individual acute exposures. 

11 
 So, it is both a DREF and an LDEF. 

12 
 So, that's why it's called a DDREF in this 

13 case. 

14 
 So, they were able to show that the 

15 
 data, a theoretic linear quadratic model and 

16 
 what you got from extrapolations down to low 

17 doses and dose rates was the same. 

18 
 CHAIRMAN RICHARDSON: I would frame 

19 
 that as interpretation of experimental 

20 
 evidence as opposed to an experiment which 

21 estimates DDREF. 

22 DR. TRABALKA: That's reasonable. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

71 

1 
 CHAIRMAN RICHARDSON: I guess for 

2 
 me, it gets to a fundamental issue of 

3 
 typically in, for me, I would like to be able 

4 
 to imagine the experiment in which I could 

5 
 test the question. 

6 
 And I can imagine the experiment in 

7 
 which I can understand differences in response 

8 
 under different magnitudes of exposure and the 

9 
 experimental design that conforms to that. 

10 
 And I can imagine the experiment 

11 
 that conforms to understanding the effect of 

12 
 protraction of the exposure over time and 

13 
 answering the question given the same 

14 
 magnitude of exposure when it's protracted, 

15 does the effect vary. 

16 
 The DDREF, I believe, is a - kind 

17 
 of a concept that was put forward for 

18 
 administrative purposes. To me, it's 

19 
 conflating those two thought experiments and, 

20 you know, for better or worse. 

21 
 So, I was just curious as to 

22 
 whether there existed an experiment like that. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

72 

1 
 DR. TRABALKA: Unfortunately, data 

2 
 are limited even for all the animal studies 

3 
 that have been done. And the Department of 

4 
 Energy terminated their animal studies before 

5 
 all such questions could be addressed. 

6 
 I would agree with you that it 

7 
 would be great to have that set of 

8 
 comparisons, but they simply don't exist. And 

9 
 so, we're left with trying to represent the 

10 data we have as best we can. 

11 
 And as I pointed out for that set 

12 
 of data for lung cancer in BALB/c mice, we 

13 
 have both acute exposure information and 

14 
 chronic exposure information. And the linear 

15 
 risk coefficient obtained from comparisons 

16 
 between the risk coefficient from the linear 

17 
 quadratic model and that from the low dose18 
 rate information agreed with one another. 

19 
 Hence, this term "DDREF" can be applied to 

20 that data set. It's both a DREF and an LDEF. 

21 
 CHAIRMAN RICHARDSON: It's an 

22 experiment that conforms to a -

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

73 

1 
 DR. TRABALKA: A hypothetical linear 

2 
 quadratic representation of the data. 

3 
 CHAIRMAN RICHARDSON: Yes. 

4 
 DR. TRABALKA: Right. 

5 
 CHAIRMAN RICHARDSON: But there's 

6 
 not an experiment that proves that it -

7 
 DR. TRABALKA: No, no. No, no. I 

8 
 would be the first to say that the animal data 

9 
 don't prove the existence of a linear 

10 quadratic dose response. 

11 CHAIRMAN RICHARDSON: Yes. 

12 
 DR. TRABALKA: I would also say the 

13 
 animal data for leukemia don't prove the 

14 
 incidence or the existence of a linear 

15 quadratic dose response. 

16 
 And if you read that section of our 

17 
 report, you'll see that that is in fact what 

18 we said. 

19 
 CHAIRMAN RICHARDSON: Very good. 

20 Thank you. 

21 
 DR. TRABALKA: Okay. Should we move 

22 on? 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

74 

1 
 Okay. Prior to 2009, some of the 

2 
 conclusions we had reached were first and 

3 
 foremost that the DDREFs in IREP didn't 

4 
 represent the uncertainties in the data, a lot 

5 
 of new information that was much greater than 

6 
 is represented in any current distribution at 

7 
 the time, including BEIR VII, and based on the 

8 
 limited information available, we suggested 

9 
 that both the LDEF and DREF data should be 

10 combined simply because of limitations. 

11 
 And at that time, we were leaning 

12 
 toward using both human and animal data and 

13 
 quantifying DDREF distributions, but things 

14 have changed since 2009. 

15 
 One of the things that's happened 

16 
 is that we've gotten the updated 

17 
 epidemiological studies of worker - nuclear 

18 
 workers in the UK, a study published by Colin 

19 Muirhead and his colleagues. 

20 
 We now have results for cancer 

21 
 incidence and mortality. We have ERRs for 

22 
 combined solid cancers, in this case, all 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

75 

1 
 cancers other than leukemia that are now 

2 
 statistically significant. 

3 
 We have the first comprehensive 

4 
 results of cancer incidence, and this adds to 

5 
 the results that came from the 15-country 

6 
 study of nuclear workers, which, despite some 

7 
 of the criticisms, is still valid, we think, 

8 
 if you include the entire Canadian cohort as 

9 
 we have done in your deliberations. 

10 
 That study suggested that the risk 

11 
 to workers exposed to low doses and dose rates 

12 
 was at least comparable to those in the A-bomb 

13 
 survivors and could, in fact, be somewhat 

14 higher. 

15 
 And the UK study suggests that 

16 
 risks in workers are comparable to those in 

17 
 the LSS cohort. And we talk about that in the 

18 
 next slide. 

19 No, no, you missed a slide. Oh, I 

20 
 guess you - we have a slide out of sequence 

21 
 here - no, we're missing a slide. What 

22 
 happened to the slide on DRFs for solid 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

76 

1 
 tumors? 

2 
 MEMBER ROESSLER: We have it in -

3 
 DR. TRABALKA: You have it in your 

4 
 handout, but I guess it went missing from 

5 
 here. 

6 
 Anyway, if you look at the page, 

7 
 the following page in your handout, if you 

8 
 look at - try to estimate a dose rate - there 

9 
 it is. That's it. 

10 
 Okay. If you estimate a dose-rate 

11 
 effectiveness factor for the UK workers 

12 
 compared to those in the LSS cohort, values 

13 
 are on the order of 1.0 to 1.4. 1.0 for the 

14 
 cancer mortality endpoint, and 1.4 for the 

15 
 cancer incidence endpoint. And of course 

16 
 there's considerable uncertainty in these data 

17 because of their origin. 

18 
 If you look at the 15-country study 

19 
 and try to do the same thing for cancer 

20 
 mortality, again emphasizing that we included 

21 
 the entire Canadian cohort, you get a DDREF 

22 
 estimate - point estimate of about 0.55 with 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

77 

1 
 considerable uncertainty. 

2 
 If you look at the data for some of 

3 
 the Chernobyl remediation workers papered by 

4 
 Ivanov and his colleagues in 2006, there's 

5 
 also cancer incidence data available from this 

6 
 cohort. 

7 
 In cancer mortality, you get a 

8 
 DDREF of 0.15 for the point estimate, which 

9 
 suggests that the risks for these people are 

10 much, much higher than the A-bomb survivors. 

11 
 However, if you look at the data 

12 
 for cancer incidence, they're about an order 

13 
 of magnitude lower. So, you get a value 

14 
 that's very close or even - I mean, the 

15 
 estimated DDREF would be either equal to or 

16 
 slightly higher than - greater than or equal 

17 
 to one. Let's put it that way and I'll stop 

18 there. 

19 
 All right. However, there are 

20 
 problems with those data. And the reason why 

21 
 we say not to be used, is because there are 

22 
 serious issues of cancer ascertainment as is 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

78 

1 
 obvious when you compare the results for 

2 
 cancer incidence and mortality, and also 

3 
 uncertainties in the doses for these folks and 

4 
 a host of other problems. 

5 
 The paper by Ivanov that was 

6 
 published in Health Physics in 2004, goes into 

7 
 detail on some of these issues. I would 

8 
 recommend that you look at that paper if 

9 
 you're interested. 

10 
 MEMBER ROESSLER: It's in your 

11 report in -

12 
 DR. TRABALKA: We discuss it in our 

13 report, yes. 

14 MEMBER ROESSLER: That's a 2004 -

15 
 MEMBER ZIEMER: This is from the 

16 
 2006 -

17 
 MEMBER ROESSLER: Sure. 

18 
 DR. TRABALKA: Can we continue? 

19 
 If we look at the data for 

20 
 responses, dose responses in the Techa River 

21 
 cohort, and try and estimate a dose-rate 

22 
 effectiveness factor for both incidence and 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

79 

1 
 mortality, and these data don't include bone 

2 
 cancer, you get a value of about 0.6. 

3 
 However, both of these papers 

4 
 provide the caution that these are preliminary 

5 
 estimates, should be interpreted with caution. 

6 
 There are all kinds of uncertainties 

7 
 especially in dose reconstruction, releases, 

8 
 confounders. 

9 
 The population along the Techa 

10 
 River is a very difficult one to use in 

11 
 comparing with any Western or Japanese cohort. 

12 
 We're talking about people who 

13 
 lived in abject poverty, had no medical care 

14 
 prior to the releases that occurred in the 

15 
 early 1950s. Only half of the 27,000 or so 

16 
 people had medical checkups from the Ural 

17 
 Center for Radiation Medicine after that point 

18 
 until -- they really didn't get interested in 

19 this until about the 1980s to 1990s. 

20 
 The attempts to dose - the problems 

21 with dose reconstruction are quite difficult. 

22 
 I would commend reading Mira 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

80 

1 
 Kossenko's report, her DTRA report. It's 

2 
 referenced in our - it's in the bibliography 

3 
 that we provided. 

4 
 She goes into great detail on this. 

5 
 And she's been involved in this effort from 

6 
 day one. 

7 
 She and one of her colleagues 

8 
 visited Oak Ridge when we were there. They 

9 
 brought some members of the Techa River 

10 
 cohort. So, we had the opportunity to find 

11 
 out firsthand some of the problems that are 

12 involved. 

13 
 In 2008, I was asked to review the 

14 
 revision of their release - radiation release 

15 study and there were major problems with it. 

16 
 It was just published in Health 

17 
 Physics this year. It was not - it was 

18 
 published too late to be included in our 

19 report. 

20 
 But one of the things that they 

21 
 have noted is that there is an order of 

22 
 magnitude spike, increase, over previous 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

81 

1 
 estimates in the last quarter of 1951 in the 

2 
 releases. 

3 
 None of this has been factored into 

4 
 these studies thus far. So, we have to be 

5 
 very cautious about this data. 

6 
 Another problem is that in the 

7 
 cancer incidence study, they were able to fit 

8 
 the data with either a linear model or a 

9 
 quadratic model. They couldn't choose between 

10 
 the two. And at, say, doses of ten milligray, 

11 
 there's a factor of 34 difference in the risk 

12 estimates. 

13 
 So, again, the long-term study of 

14 
 this cohort may provide some useful 

15 
 information, but we prefer not to use it in 

16 our DDREF calculations at this point. 

17 
 MEMBER MUNN: You're not ever going 

18 to have a viable baseline though. 

19 
 DR. TRABALKA: Well, that's another 

20 issue. I agree with you. 

21 Shall we continue? 

22 MEMBER MUNN: Sure. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

82 

1 
 DR. TRABALKA: Okay. Now, also in 

2 
 2009, a rather influential paper appeared by 

3 
 Peter Jacob and his colleagues and it was a 

4 
 synthesis of 12 occupational environmental 

5 
 exposure studies. 

6 
 They compared risk with the LSS 

7 
 cohort attempting to match the ages at 

8 
 exposure and attained - they attempted to do 

9 
 this. It's rough, but I think they did a good 

10 
 job on that part of the study. And rather 

11 
 than calculate DDREFs, they calculated risk 

12 ratios. 

13 
 In other words, comparing risks in 

14 
 the worker cohort or the Techa River study, 

15 
 for example, with those in the A-bomb 

16 
 survivors, but flipping it using the inverse 

17 of DDREF. 

18 
 And what that does is helps you 

19 
 avoid infinities that occur in calculations, 

20 
 because you have dose responses where the 

21 
 ERRs, for example, are so wide that they go 

22 
 below zero on a lower bound of the confidence 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

83 

1 
 limits. They applied an inverse variance 

2 
 approach to weighting the values. The 

3 
 equivalent DDREFs in the 12 studies range from 

4 
 0.05 to infinity. 

5 
 But when they do their inverse 

6 
 variance weighting scheme, they come out with 

7 
 risk ratios of greater than one that convert 

8 
 to DDREFs of 0.5 to one. 0.5 to one. Inverse 

9 
 of one is one. 

10 So, anyway, what they did is they 

11 
 developed three groupings of occupational and 

12 
 environmental exposure data for either cancer 

13 mortality or incidence. 

14 
 They had one group where they had 

15 
 seven sets of data on cancer morality, another 

16 
 group where they had four - a different group 

17 
 with four sets of data on cancer mortality, 

18 
 and then one group that had three sets of 

19 information on cancer incidence only. 

20 
 The main result was based on the 

21 
 seven studies of cancer mortality and the risk 

22 
 ratio was 1.2. And then when you invert it, 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

84 

1 
 you come up with a DDREF of roughly 0.8 with 

2 
 confidence limits of 0.53 to two. 

3 
 Now, there are a number of issues 

4 
 with that study. And I won't go into all of 

5 
 them, because there's a whole section of our 

6 
 report that covers it. 

7 
 I found several more issues with it 

8 
 in getting ready for this meeting. So, those 

9 
 will have to be included at a later date. 

10 
 There are many who thought this was 

11 
 the answer when it came to DDREF, but then 

12 
 there were a lot of people who thought that 

13 
 the BEIR VII report was the answer, and there 

14 
 were a number of people who thought that the 

15 
 French National Academy study was the answer, 

16 
 and none of these studies agreed with one 

17 
 another. And certainly the DDREF estimates 

18 they produced would be very, very different. 

19 
 Before we move on, are there any 

20 questions about this? 

21 
 MEMBER ROESSLER: What section of 

22 your report is it in? 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

85 

1 
 DR. TRABALKA: I can't give you the 

2 
 exact section right now. It starts on Page 

3 
 149. 

4 
 MEMBER ROESSLER: That's good 

5 
 enough. It's such a big report. 

6 
 DR. TRABALKA: A mighty tome. 

7 
 MEMBER ROESSLER: Yes, it is. 

8 
 DR. TRABALKA: And as some of my 

9 
 colleagues would say, opaque. 

10 (Laughter.) 

11 MEMBER MUNN: Nicely done. 

12 
 DR. TRABALKA: Are we ready to 

13 continue? 

14 
 DR. KOCHER: Could you allude to 

15 some of the problems with that study, maybe? 

16 
 DR. TRABALKA: Well, one of the 

17 
 problems of course is that they used - despite 

18 
 the fact that most of these studies did not 

19 
 have normally distributed confidence limits 

20 
 and they assumed that they were normally 

21 
 distributed and estimated a standard error, 

22 
 and then they - so they have ratio - and this 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

86 

1 
 includes the A-bomb survivor data. 

2 
 So, they have ratios of two normal 

3 
 distributions, which produces a Cauchy 

4 
 distribution, which has an undefined mean and 

5 
 variance. 

6 
 The median is well-defined, but a 

7 
 Cauchy distribution has very long tails. 

8 
 Their results were given as 90 percent 

9 
 confidence intervals. 

10 
 And if you look at the results and 

11 
 you start looking at 95 percent and 99 percent 

12 
 confidence, you see that they've ballooned. 

13 So, there's some issues related to that. 

14 
 I'm not going to hit them over the 

15 
 head with that part because, you know, they 

16 
 were trying to come up with a better way of 

17 
 looking at the data to estimate what DDREFs or 

18 risk ratios might be. 

19 
 Data selection is a bigger issue. 

20 
 We think that more consideration should have 

21 
 been given to weighting the studies according 

22 
 to their value and their - as I pointed out, 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

87 

1 
 there are problems with the Chernobyl worker 

2 
 studies, the clean-up workers, the Techa River 

3 
 studies. 

4 
 They also were limited in some of 

5 
 the studies that they used. For example, they 

6 
 left out the nuclear power plant worker study 

7 
 by Howe and company, they left out the Cogema 

8 
 Nuclear Power Plant worker study by Rogel and 

9 
 company, and the Idaho National Laboratory 

10 
 study by Mary Schubauer-Berigan and her 

11 colleagues from NIOSH. 

12 
 In the 15-country study, all three 

13 
 of those cohorts were assigned a negative 

14 
 risk. Of course if you would put those back 

15 
 into this deliberation, I think you're going 

16 to change the results somewhat. 

17 
 Also, the - well, that's enough for 

18 
 now. I would rather that you read that 

19 
 section. And then if you have any questions, 

20 
 I'd be happy to answer them. Written 

21 responses, or just talk to you on the phone. 

22 
 DR. KOCHER: Yes, there have been a 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

88 

1 
 lot of studies of various kinds that have done 

2 
 this inverse variance weighting scheme. And 

3 
 that just always raises a red flag in my mind, 

4 
 that's a way to deflate uncertainty and -

5 
 DR. TRABALKA: I don't like to 

6 
 deflate uncertainty unless I have a really 

7 
 good reason for so doing. 

8 
 Should we move on? 

9 
 MR. KATZ: I thought David 

10 Richardson had some questions. 

11 
 David, did you have some questions 

12 or points? 

13 
 CHAIRMAN RICHARDSON: Yes. Well, 

14 there were two questions. 

15 
 Right now you're reviewing 

16 
 literature, if I'm correct, which is focusing 

17 
 on dose-rate effects. These are the Jacob and 

18 
 the workers compared to the LSS, and public 

19 
 and environmental exposures compared to the 

20 LSS. 

21 
 You're focused on investigations in 

22 
 which an estimate under a linear model for the 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

89 

1 
 magnitude of excess risk per unit dose is 

2 
 compared between populations where you're 

3 
 presuming the exposures are protracted over 

4 
 time, to populations in which there's an acute 

5 
 exposure. 

6 
 DR. TRABALKA: That's correct. And 

7 
 linear risk coefficients are being compared in 

8 
 both cases. 

9 
 CHAIRMAN RICHARDSON: Right. So, 

10 
 this is one - as I'm trying to map this out to 

11 
 my thought experiment and to - this is a focus 

12 
 on the category of solid cancer risk estimates 

13 
 when we have protraction over time and 

14 exposure. 

15 DR. TRABALKA: That's correct. 

16 
 CHAIRMAN RICHARDSON: And we're not 

17 
 looking at leukemia here, because the thought 

18 
 experiment is that the acute exposure response 

19 
 shape is - does not have a magnitude - the 

20 
 magnitude of that relationship is not affected 

21 
 by whether the dose rate is higher or lower. 

22 
 Which, to me, is an empirical question, but 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

90 

1 
 it's an assumption that's built into that. 

2 
 I would like to separate out the 

3 
 categories of the shape of the exposure 

4 
 response curve, where you can do a dosing 

5 
 experiment and for a given magnitude of dose 

6 
 we see that the response varies as a linear 

7 
 quadratic function, and then we protract that 

8 
 exposure over time and we might ask whether 

9 
 the response is insensitive to the protraction 

10 of exposure over time. 

11 DR. TRABALKA: Right. 

12 
 CHAIRMAN RICHARDSON: That's off the 

13 table here, right? 

14 
 DR. TRABALKA: Well, specifically 

15 
 for leukemia for chronic exposure, what is 

16 
 done is to take the linear risk coefficient 

17 from the linear quadratic model and apply -

18 
 CHAIRMAN RICHARDSON: I understand. 

19 I understand that. I'm pointing out that -

20 
 DR. TRABALKA: But the issue of 

21 
 whether or not there is also information that 

22 
 would suggest that you need to apply, let's 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

91 

1 
 say, a DDREF to that is still an issue. 

2 
 And I think at the moment, we 

3 
 simply don't have enough information to be 

4 
 able to answer that question. 

5 
 CHAIRMAN RICHARDSON: I think we 

6 
 have all exactly the same information, 

7 
 actually, as we do for the solid cancers. 

8 
 There are leukemias in the A-bomb data, and 

9 
 there are leukemias in all of these 

10 epidemiologic cohorts. 

11 
 DR. TRABALKA: But what we don't 

12 
 have is the latest iteration based on the DSO2 

13 
 dose response for leukemia in the A-bomb 

14 survivors. That has yet to be published. 

15 
 CHAIRMAN RICHARDSON: For what 

16 outcomes are you considering? 

17 
 DR. TRABALKA: Leukemia, multiple 

18 myeloma, lymphoma -

19 
 CHAIRMAN RICHARDSON: You mean for 

20 mortality? 

21 
 DR. TRABALKA: No, no, incidence. 

22 
 Remember, IREP is used to estimate cancer 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

92 

1 
 incidence. 

2 
 CHAIRMAN RICHARDSON: But we've just 

3 
 been reviewing a set of comparisons most of, 

4 
 for example, Jacob's work, I believe, is 

5 
 mortality data, right? 

6 
 DR. TRABALKA: Yes. And for cancer 

7 
 incidence, the DDREF is about one, for 

8 
 example, based on the three studies that they 

9 
 included. 

10 I think if you take out the data 

11 
 for the Techa River studies and then redo it, 

12 
 you get a DDREF that's close to one and a 

13 half, but that's for the future discussion. 

14 CHAIRMAN RICHARDSON: Yes. 

15 
 DR. TRABALKA: That's not covered in 

16 
 our report. 

17 CHAIRMAN RICHARDSON: And you said 

18 
 that the French Academy came to a different 

19 
 conclusion than the, what I would call a meta20 analysis by Jacob. 

21 
 Did they do their own meta-analysis 

22 
 of these empirical data, or did they derive 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

93 

1 
 their conclusions some other way? 

2 
 DR. TRABALKA: They weren't looking 

3 
 specifically at DDREF. They were looking at 

4 
 the - or reviewing dose response model 

5 
 information. 

6 
 So, they were reacting to the BEIR 

7 
 VII report that suggested there should be 

8 
 linearity in the low-dose response. And their 

9 
 conclusion was that phenomena such as hormesis 

10 
 and thresholds were very highly likely at low 

11 doses and dose rates. 

12 
 And so, the issue was on the dose 

13 
 response, of course that has a tremendous 

14 effect on potential DDREFs. 

15 
 CHAIRMAN RICHARDSON: So, it wasn't 

16 
 derived from, let's say, observational data 

17 from epidemiologic studies and -

18 
 DR. TRABALKA: They included 

19 
 epidemiological studies in their evaluation, 

20 
 yes. But it was mostly based on animal 

21 
 studies, laboratory studies and things like 

22 that. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

94 

1 
 CHAIRMAN RICHARDSON: Thanks. 

2 
 DR. TRABALKA: Okay. Ready to move 

3 
 on? 

4 
 So, anyway, as I said back around 

5 
 2009 we thought probably it would be best to 

6 
 combine human and animal data. But now, our 

7 
 current approach focuses on human 

8 
 epidemiological data for combined solid tumors 

9 
 to estimate a DDREF. 

10 
 We have attempted to estimate DDREF 

11 
 distributions for thyroid and breast cancer 

12 
 and we've compiled information on lung and 

13 bone cancers. 

14 
 And we're going to use animal data 

15 
 - or have used animal data as a check on our 

16 
 results, but not in quantitative derivation of 

17 the DDREF distribution. 

18 
 And we concluded from our review 

19 
 that separate distributions for thyroid and 

20 
 breast cancers are not warranted, because 

21 
 there's much more uncertainty in the dose 

22 responses than formerly considered. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

95 

1 
 The EPA in its 2011 revision of the 

2 
 blue book, basically came to the same 

3 
 conclusion. They're using common DDREF for 

4 
 all solid cancers. 

5 
 Now, there was another point I was 

6 
 going to make here, but it's flown away. So, 

7 
 I'll wait and respond to questions. 

8 
 (No response.) 

9 
 DR. TRABALKA: Oh, okay. That's 

10 good. Go on. Let's go on to the next slide. 

11 
 This slide summarizes some of the 

12 
 information, but the information that we did 

13 
 involves studies where we have combined solid 

14 
 cancer data available for estimation of DDREF. 

15 
 Comparing the results from the UK 

16 
 worker study, the updated worker study with 

17 
 the LSS cohort gives us a DDREF. And these 

18 
 are 90 percent confidence intervals shown on 

19 this slide, I should point out. 

20 
 The next two values are LDEFs that 

21 
 were obtained from the latest iteration of A22 
 bomb survivor data, basically the DSO2-based 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

96 

1 
 dose response information sets. 

2 
 BEIR VII and Preston and company in 

3 
 a 2007 paper, produced results that are very 

4 
 similar. The uncertainties are different, but 

5 
 the point estimates are identical of DDREFs -

6 
 or LDEFs at 1.3. 

7 
 Continue on. The next set of data 

8 
 are those on cancer mortality from a variety 

9 
 of studies. There's only one DS86-based data 

10 
 set there. That's the one from Linda Walsh 

11 and her colleagues published in 2004. 

12 
 A variety of estimates obtained 

13 
 from the RERF folks typically for mortality, 

14 
 the point estimates are between one - are 

15 closer to two than one. 

16 
 The linear quadratic exponential 

17 
 model that Little and his colleagues developed 

18 
 for the UNSCEAR report has very wide 

19 
 confidence limits. It was reported to fit the 

20 
 data better than linear quadratic model, but 

21 
 it has extremely wide confidence limits and 

22 
 its point estimates are slightly greater than 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

97 

1 
 two. 

2 
 If we look at the comparisons 

3 
 between the 15-country study including the 

4 
 entire Canadian cohort and that with the UK 

5 
 workers using mortality, you get values as I 

6 
 mentioned earlier from 0.55 to around one. 

7 
 Now, what we did is we assign a 

8 
 much higher weight to values based on cancer 

9 
 incidence, because IREP is -- the endpoint in 

10 IREP is cancer incidence. 

11 
 We assign essentially equal weights 

12 
 between the A-bomb survivor data and that 

13 
 obtained from comparisons between worker 

14 studies and the LSS cohort. 

15 
 That can be argued as, you know, it 

16 
 should be looked at, but we applied a wide 

17 
 range of sensitivity and uncertainty studies 

18 to our result. 

19 
 We even looked at assigning a 

20 
 higher weight to a fixed value of one. We 

21 assigned a 25 percent weight for that. 

22 
 In another case, we assigned a 25 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

98 

1 
 percent weight to a threshold which is the 

2 
 value of infinity and we did that in 

3 
 combination. And what you find in doing that 

4 
 is that the point estimates don't vary all 

5 
 that much. 

6 
 The upper bounds on the DDREF 

7 
 distributions of course vary tremendously. If 

8 
 you put a value of infinity in there, your 

9 
 upper bound is going to be infinity, but the 

10 
 lower end of the confidence limits and the 

11 
 point estimates don't vary by much with a 

12 
 result that it's that region of the DDREF 

13 
 distribution that drives the 99th percentile 

14 of PC in IREP. 

15 
 So, you don't - in fact, most of 

16 
 the distributions we came up with would 

17 
 probably produce - will produce higher 

18 
 estimates of PC than in current distribution 

19 
 in IREP. 

20 
 Well, let's continue on. 

21 
 DR. NETON: I want to explore that a 

22 
 little bit. You're saying you did sensitivity 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

99 

1 
 analyses. 

2 
 DR. TRABALKA: Right. 

3 
 DR. NETON: Explain that a little 

4 
 more to me. 

5 
 DR. TRABALKA: We looked at 

6 
 different weights, the assignment of different 

7 
 weights, for example, to the incidence data 

8 
 versus the mortality data. 

9 
 We ran a case where the - all of 

10 
 our results were done using Monte Carlo 

11 simulations. 

12 DR. NETON: Right, yes. 

13 
 DR. TRABALKA: And we did - and we 

14 
 ran cases where we did attempt an inverse 

15 
 variance approach to the data to try and 

16 reduce uncertainty. 

17 
 But with all of the ones we ran, as 

18 
 I pointed out, we didn't have a big - the 

19 
 point estimates varied from 1.1 to 1.6, with a 

20 center probably around 1.3. 

21 
 DR. HOFFMAN: In an attempt to come 

22 
 up with a state of knowledge distribution 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

100 

1 
 representing uncertainty on DDREF, we looked 

2 
 at multiple approaches. This is what's called 

3 
 their sensitivity analysis. 

4 
 DR. NETON: Right. 

5 
 DR. HOFFMAN: So, we have our 

6 
 preferred approach, and then the report - I 

7 
 don't know if that section has been delivered 

8 
 or not. 

9 
 So, this is the section of the 

10 
 report that hasn't been delivered, which would 

11 
 show the outcome of the sensitivity analysis 

12 
 and how many different iterations were used to 

13 
 not only express our overall state of 

14 
 knowledge, but to look at the impact of these 

15 
 various distributions of DDREF on the upper 

16 
 99th percentile of the Probability of 

17 Causation for specific diseases. 

18 DR. NETON: In hypothetical cases? 

19 
 DR. HOFFMAN: In hypothetical cases. 

20 
 DR. NETON: See, my concern is that 

21 
 the central estimate really is what's going to 

22 
 drive a change in PC, because the 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

101 

1 
 distributions are so tight compared to the 

2 
 other uncertain distributions in IREP. 

3 
 Any incremental change in the 

4 
 central estimate of the DDREF will result in a 

5 
 corresponding incremental change in the PC 

6 
 calculation. 

7 
 So, the central estimate really - I 

8 
 don't care how much wider you make your 

9 
 uncertainty bounds on that distribution, it's 

10 
 not, I don't think, going to have much of an 

11 affect on the overall PC change. 

12 
 What will change is probably a 

13 change in central -

14 
 DR. HOFFMAN: But what we're saying 

15 
 is central estimates don't change much. Nor 

16 
 does the lower bound. But the upper bounds 

17 change dramatically. 

18 
 DR. TRABALKA: But what Iulian and 

19 
 Brian discovered in looking at what was 

20 
 driving PC from DDREF distributions, was that 

21 
 values between the fifth and the 40th 

22 
 percentile were driving the 99th percentile PC 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

 

 

102 

1 
 estimates. 

2 
 So, it is the lower end of the 

3 
 distribution. 

4 
 DR. NETON: I don't know if you 

5 
 tried it with real cases or not. 

6 
 DR. TRABALKA: Well, no. Obviously 

7 
 we couldn't. 

8 
 DR. NETON: You can only do so much 

9 
 in a hypothetical situation. 

10 DR. TRABALKA: That's correct. 

11 
 DR. NETON: I think if you try real 

12 cases, you might see something different. 

13 
 DR. TRABALKA: And you could argue 

14 
 that we need to do additional sensitivity 

15 analysis. That's a fair statement. 

16 
 CHAIRMAN RICHARDSON: So, have you 

17 ended up with a histogram? 

18 
 DR. TRABALKA: Actually, we have 

19 
 developed continuous distributions, not 

20 histograms. 

21 
 CHAIRMAN RICHARDSON: And when you 

22 
 were describing the upper tail, I'm imagining 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

103 

1 
 a distribution that has a long tail on the 

2 
 right. 

3 
 DR. TRABALKA: Well, for example, 

4 
 I'll give you an example of how it might look. 

5 
 A point estimate, let's say, of around 1.3, 

6 
 fifth percentile at 0.5, and 95th percentile 

7 
 at five. 

8 
 That's just one, you know, that 

9 
 might represent our preferred distribution at 

10 
 the moment. That could change with future 

11 analysis. 

12 
 You can compare that with what you 

13 
 get when comparing the studies - or the study 

14 
 of Jacob of the history cases and with the 

15 
 distribution that's currently in IREP for the 

16 
 combined solid cancers and that from the BEIR 

17 
 VII DDREF distribution. 

18 
 Both of those have tighter 

19 confidence limits. 

20 
 MEMBER ZIEMER: Could you clarify on 

21 
 the third -- or the second study by Little, 

22 what does that say at the low end of that? 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

104 

1 
 DR. TRABALKA: It means that the 

2 
 confidence limits were wide enough they would 

3 
 have extended below zero for a DDREF when you 

4 
 do a Monte Carlo simulation. 

5 
 MEMBER ZIEMER: Oh. 

6 
 DR. TRABALKA: They provided 

7 
 parameters for a linear quadratic exponential 

8 
 model with uncertainty. 

9 
 And when you run a Monte Carlo 

10 
 simulation, what that represents in terms of a 

11 DDREF, that's what you get. 

12 MEMBER ZIEMER: Is that a minus 13? 

13 
 DR. TRABALKA: Minus 13, that's 

14 correct. That's correct. 

15 MEMBER ZIEMER: All right. 

16 
 DR. MAURO: This is John. Quick 

17 question. 

18 
 When you get a minus, would that be 

19 interpreted as a hormetic effect? 

20 
 DR. TRABALKA: It could be, or it 

21 
 could just be representing noise because of 

22 the wide uncertainty. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

105 

1 
 DR. MAURO: Okay. 

2 
 DR. TRABALKA: I would interpret it 

3 
 as a hormetic effect. And of course in IREP 

4 
 since values less than zero are - or the risk 

5 
 distributions are truncated at zero, we 

6 
 probably should have truncated that right at 

7 
 zero ourselves, but we just wanted to show the 

8 
 entire data set. 

9 
 DR. MAURO: One follow-up question 

10 on that. 

11 
 In the 95 percent confidence 

12 
 intervals that you have been discussing, do 

13 
 any of those intervals include negative values 

14 
 if you propagated the distribution without 

15 truncating? 

16 
 DR. TRABALKA: Which distribution? 

17 
 These are all 90 percent confidence intervals. 

18 
 DR. HOFFMAN: He doesn't have 

19 
 slides. 

20 DR. TRABALKA: Oh, sorry. These are 

21 all -

22 
 DR. MAURO: Yes, unfortunately, I 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

106 

1 
 don't have slides. 

2 
 DR. TRABALKA: No, in our preferred 

3 
 distribution, we have no negative values. 

4 
 DR. MAURO: Okay. Thank you. 

5 
 MEMBER ROESSLER: Can I ask a 

6 
 question on this? 

7 
 CHAIRMAN RICHARDSON: It seems to me 

8 
 you'd be more concerned about values of zero 

9 
 than even negative values. 

10 
 You take the risk coefficient and 

11 divide it by zero and get infinity. 

12 DR. TRABALKA: Yes. 

13 
 DR. HOFFMAN: None of our 

14 distributions have zero. 

15 DR. TRABALKA: Go ahead. 

16 
 MEMBER ROESSLER: Yes, just looking 

17 
 at this figure and looking at your central 

18 
 estimates, I don't totally understand all your 

19 sensitivity analysis. 

20 
 But it seems like if you, for the 

21 
 time being, kind of set the Jacob studies 

22 
 aside, that you're putting a lot of emphasis 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

107 

1 
 on the Cardis or the 15-county data, you know, 

2 
 compared to all those other sets that appear 

3 
 in kind of a grouping there. 

4 
 DR. TRABALKA: Well, actually I 

5 
 should have given you some more details of how 

6 
 we did all this. 

7 
 DR. KOCHER: The answer isn't shown 

8 
 here. 

9 
 DR. TRABALKA: Well, I know. 

10 MEMBER ROESSLER: Okay. 

11 
 DR. TRABALKA: And of course there's 

12 a reason for that. 

13 
 But when we pooled the data, we 

14 
 first pooled all of the LDEF information from 

15 
 the A-bomb survivors, ran a Monte Carlo 

16 
 simulation that applied roughly equal weights 

17 
 to each one of those values that's represented 

18 
 by a solid triangle, slightly lower weight to 

19 
 the value for Walsh and company's value simply 

20 
 because they didn't provide a lower confidence 

21 limit and we had to estimate it. 

22 
 Once we got that answer, we pooled 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

108 

1 
 it with the information obtained from the 

2 
 comparison of the 15-country study and the UK 

3 
 study, but those two sets were given equal 

4 
 weight. 

5 
 So, the 15-country study is not 

6 
 dominating at this point. 

7 
 MEMBER ROESSLER: Okay. Then another 

8 
 question. The French Academy study, you 

9 
 mentioned that earlier. And you're not 

10 
 considering that, and can you give me some 

11 
 reasons why that was not part of your 

12 evaluation? 

13 
 DR. TRABALKA: Well, we evaluated 

14 
 that information. ICRP evaluated it in their 

15 
 2005 report, and we just don't think that 

16 
 there's enough credible information in that 

17 report to use. 

18 
 DR. NETON: That wasn't really a 

19 DDREF study. 

20 
 DR. TRABALKA: No, it wasn't a DDREF 

21 study. 

22 
 DR. NETON: It was really a 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

109 

1 
 commentary on LNT. That's my recollection. 

2 
 DR. TRABALKA: Exactly. Exactly. 

3 
 DR. KOCHER: And one of the things 

4 
 that I try to remember in this whole business 

5 
 is that we're starting with an LNT model. 

6 
 That's a given. 

7 
 And so, we're trying to estimate if 

8 
 DDREF would apply to that model, warts and 

9 
 all. 

10 MEMBER MUNN: And I think that we 

11 challenge that concept. 

12 
 DR. KOCHER: Yes, but that's not -

13 the rules of the game have been fixed. 

14 
 DR. TRABALKA: I should also point 

15 
 out that a brand new study of the A-bomb 

16 
 survivors, cancer mortality in the A-bomb 

17 survivors has just been published in 2012. 

18 
 And the DDREF estimate we've 

19 
 obtained from that set of information is 1.8. 

20 
 And so, it falls within the range of all 

21 these other values. 

22 
 However, there were some other 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

110 

1 
 interesting ramifications to that study that 

2 
 suggest that you have to be cautious in 

3 
 writing off super linearity at low doses. 

4 
 So, that's why values less than one 

5 
 cannot be eliminated from DDREF distributions. 

6 
 We have to be very, very cautious right now. 

7 
 We have plenty of indications of 

8 
 supralinearity in some of the human data. 

9 
 MEMBER ROESSLER: And this new study 

10 is by whom? 

11 
 DR. TRABALKA: Ozasa et al. I think 

12 
 it's the first one that I've seen where Donald 

13 
 Pierce and Dale Preston haven't been involved. 

14 
 MEMBER ROESSLER: And where was this 

15 published? 

16 
 DR. TRABALKA: In Radiation 

17 
 Research. 

18 MEMBER ROESSLER: Okay. Okay. 

19 
 DR. TRABALKA: I think it may be 

20 
 January. Somewhere in the January to March 

21 frame. 

22 DR. HOFFMAN: So, fairly recent. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

111 

1 
 DR. TRABALKA: Yes, well after the 

2 
 draft date of our report. 

3 
 MR. KATZ: Do folks want to break? 

4 
 We've been going at it for an hour and a half 

5 
 or more. 

6 
 DR. TRABALKA: There's one more 

7 
 slide, but it's just a quick wrap-up. 

8 
 MR. KATZ: That's fine. That's 

9 
 fine. Why don't we do that? That makes sense 

10 then. 

11 
 DR. TRABALKA: Well, basically our 

12 
 own conclusion is that we can develop a 

13 
 distribution of DDREF that represents the 

14 
 current state of knowledge, it has wider 

15 ranges, a central estimate closer to one. 

16 
 It contains also most of the point 

17 
 estimates from the animal data. It's just 

18 
 that they're not given the highest priority as 

19 
 they have been in the past in some of the 

20 estimates. 

21 
 However, our conclusions are 

22 
 preliminary until selection and interpretation 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

112 

1 
 of our data and our choices of alternative 

2 
 distributions have been vetted. That has not 

3 
 been done. 

4 
 We've tried to get some comments 

5 
 from the ICRP Committee on Section 5 and our 

6 
 approach to doing DDREF distribution 

7 
 estimates, but we have not been successful 

8 
 thus far except for the comments from Peter 

9 
 Jacob. 

10 However, one thing that Peter Jacob 

11 
 did that was very useful, was the idea of 

12 
 using risk ratios where you invert -- it's the 

13 
 inverse of DDREF to avoid infinities in 

14 calculation. 

15 
 So, in future it might be better to 

16 
 try and do calculations that way and it would 

17 
 simplify calculations. At least give 

18 
 consideration for doing that in the future. 

19 And that's it. 

20 
 MR. KATZ: David, before we go on 

21 
 break, David, Bill or Dick, do you have any 

22 questions you want to raise before we break? 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

113 

1 
 CHAIRMAN RICHARDSON: No, I suggest 

2 
 we take a break. 

3 
 MR. KATZ: Okay, good. So, we'll 

4 
 rejoin in 15 minutes, maybe, which will be 

5 
 about 11:00. 

6 
 (Whereupon, the proceedings went 

7 
 off the record at 10:48 a.m. and resumed at 

8 
 11:01 a.m.) 

9 
 MR. KATZ: Okay, everyone's back in 

10 
 the room, but let me check on the line. Do we 

11 have David and Bill and Dick? 

12 MEMBER FIELD: Bill is here. 

13 
 CHAIRMAN RICHARDSON: David 

14 Richardson, yes, I'm here. 

15 
 MR. KATZ: Okay. I don't hear Dick, 

16 but I think we can restart. So where are we? 

17 
 DR. TRABALKA: We're done with our 

18 
 component, except for questions that folks 

19 still want to ask. 

20 
 MR. KATZ: So, I don't know if you 

21 
 could hear John. He's offering up if there 

22 
 are questions people want to raise, they're 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

114 

1 
 finished presenting. 

2 
 CHAIRMAN RICHARDSON: Maybe we could 

3 
 start with a question about the timeline that 

4 
 NIOSH is imagining for kind of finalizing and 

5 
 releasing a draft of this report for the 

6 
 Committee on those final sections. 

7 
 DR. NETON: Good question, David. 

8 
 This is Jim. I think that we need - NIOSH 

9 
 would like to submit this report for external 

10 
 peer review very much like we did the 

11 
 radiation effectiveness factor work, or that 

12 SENES did. 

13 
 We would solicit at least three 

14 
 subject matter experts, up to five, to provide 

15 
 comment on the full report, including the 

16 conclusionary sections. 

17 
 We're willing to move forward with 

18 
 that very quickly as soon as, I think, John 

19 
 wants to make a couple changes to some errors 

20 that he's noticed in the report. 

21 
 But that process is not probably, 

22 
 from my experience, going to be real quick. I 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

115 

1 
 mean, we have to allow - we have to first 

2 
 identify the experts, get them to agree. It's 

3 
 a fairly lengthy report. I would envision 

4 
 that in the three to six-month time frame is 

5 
 where I would go. 

6 
 But I think at this point, 

7 
 sufficient information, it's been 

8 
 consolidated, put together, that it's got to 

9 
 go out for review. 

10 
 And until we get that input, I 

11 
 don't know that we can release the - I would 

12 not feel comfortable releasing a full report. 

13 
 CHAIRMAN RICHARDSON: No, sure. I 

14 was just wondering how -

15 
 DR. NETON: And once that occurs, 

16 
 though, I think then we would open this 

17 
 document up for -- essentially, I would think 

18 at that point. 

19 
 And I need to work this through the 

20 
 process, but I would assume that we would open 

21 
 it up for public comment, which would include 

22 
 the Working Group, and at some point the full 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

116 

1 
 Board as well, with our recommended path 

2 
 forward. 

3 
 We would take the subject matter 

4 
 experts, respond to their - working with 

5 
 SENES, respond to their comments, concerns, 

6 
 and then adopt a position. 

7 
 We're treading somewhat cautiously 

8 
 here, because this is a major, major change to 

9 
 IREP. We've done other changes in the past 

10 
 that were minor, in my opinion, compared to 

11 this. 

12 
 And I'm struggling with the idea of 

13 
 our charge to rely on consensus science for 

14 
 our scientific approaches. And at this point 

15 
 right now, we have our contractor's opinion as 

16 
 to where things are and we'll move forward 

17 
 with the subject matter expert reviews, and 

18 then full public comment. 

19 
 So, it will be three to six months, 

20 I guess, is the best I can -

21 
 MEMBER ROESSLER: So, you think you 

22 
 can get the subject matter reviewers 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

117 

1 
 accomplished in three to six months? 

2 
 DR. NETON: Well, probably closer to 

3 
 six months. 

4 
 MEMBER ROESSLER: Yes. 

5 
 DR. TRABALKA: With some arm 

6 
 twisting. 

7 
 MEMBER ZIEMER: That's at the 40 

8 
 percent confidence level. 

9 
 (Simultaneous speaking.) 

10 
 DR. NETON: I would say six months 

11 
 is doable. I mean, if we could identify 

12 
 folks, we have a fairly quick mechanism. We 

13 
 don't - we will essentially do this like we do 

14 other documents of this type. 

15 
 We would offer an honorarium. We 

16 
 don't hire people to do this. We offer an 

17 honorarium to review it and it goes quicker. 

18 
 And then it's just a matter of 

19 
 finding someone with the time to read almost a 

20 
 400-page report, which maybe six months is a 

21 little bit optimistic because it's a tome. 

22 
 MEMBER ROESSLER: So, you at NIOSH 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

118 

1 
 pick the reviewers. 

2 
 DR. NETON: Yes, that's the way 

3 
 we've worked it in the past. I think it's 

4 
 incumbent upon us to do that. 

5 
 We certainly accept input from 

6 
 anyone as to what potential reviewers would be 

7 
 available or might be appropriate because we 

8 
 would want to get a spectrum of reviews, not 

9 
 just one-sided. 

10 
 MEMBER ZIEMER: Is SENES done with 

11 those missing sections or close to done? 

12 DR. NETON: Oh, they're done. 

13 
 DR. HOFFMAN: The missing sections 

14 are complete. 

15 
 DR. NETON: Yes, I just - it's been 

16 
 my holdback or at my request that they be held 

17 
 back because I'm not comfortable releasing 

18 
 their conclusions given the document had not 

19 really been reviewed externally. 

20 MEMBER ZIEMER: Gotcha. 

21 
 DR. KOCHER: The business about 

22 
 consensus is tricky. I mean, I can't sit in 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

119 

1 
 your seat politically, but the REF work was 

2 
 certainly not any kind of consensus thing 

3 
 because it was new and a consensus -- consensi 

4 
 take time to develop after new stuff comes 

5 
 out. 

6 
 Now, this is not a new concept, but 

7 
 the approach to doing it is, in my judgment, 

8 
 pretty new. 

9 
 DR. NETON: Well, to the extent 

10 
 there are other consensus organizations out 

11 
 there that have a different opinion. I mean, 

12 
 the BEIR VII report, it differs from that. I 

13 
 guess what else is - does UNSCEAR have their 

14 own distribution? I think that they -

15 
 DR. TRABALKA: UNSCEAR uses a linear 

16 
 quadratic model for cancer mortality. So, 

17 
 they don't apply DDREF. It's inherent in the 

18 model. 

19 
 And for cancer incidence, they just 

20 
 said, hey, it's close enough to linearity, 

21 
 we're not going to worry about it, we're just 

22 
 going to use the value of one, just assume 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

120 

1 
 it's one. 

2 
 DR. NETON: So, to some extent, this 

3 
 is groundbreaking, I mean, what we're doing 

4 
 here. And I'm, like I said, we're moving 

5 
 cautiously. 

6 
 But I would be comfortable going 

7 
 out and getting three, hopefully up to five, 

8 
 independent reviews that we would solicit, get 

9 
 those reviews back, work to address the 

10 concerns. 

11 
 And then I'm reasonably certain 

12 
 that we would go out for public comment in 

13 
 some kind of a Federal Register Notice to say, 

14 
 here is our intent. Once we formulate and 

15 
 come to a conclusion based on the report, the 

16 revised report, this would be our intent. 

17 
 Or, I mean, that's presuming that 

18 
 we came to conclusion to revise the DDREF. I 

19 
 mean, I don't want to presume that all the 

20 
 comments that we see come back, you know, and 

21 
 say, yes, this is the greatest thing to do and 

22 proceed down this path. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

121 

1 
 It's also possible that a 

2 
 conclusion could be made that now is not the 

3 
 appropriate time. I don't know. I don't want 

4 
 to comment either way, I guess. 

5 
 MEMBER MUNN: Well, "consensus" is a 

6 
 dangerous word. 

7 
 DR. NETON: Yes, it is. 

8 
 MEMBER MUNN: And certainly human 

9 
 history has not shown it to be always the 

10 
 wisest choice with respect to scientific 

11 
 endeavors. So it would be wise to be cautious 

12 with that. 

13 
 MR. KATZ: Yes, I think just to 

14 
 clarify what we said up front in the 

15 
 regulations about new science was that as 

16 
 authoritative groups and so on, consensus 

17 
 groups produce new findings, recommendations, 

18 
 those would be taken into account and serve as 

19 
 drivers for the program to reconsider its 

20 
 science, but that doesn't limit the program to 

21 only awaiting, BEIR reports, etc. 

22 
 MEMBER ROESSLER: So, as a Work 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

122 

1 
 Group, what is our - I guess David maybe knows 

2 
 the answer to this. But as a Member of the 

3 
 Work Group, what is our responsibility at this 

4 
 point? 

5 
 Just to follow the development as 

6 
 it goes and be prepared to present to the 

7 
 Board what we've observed and -

8 
 MEMBER ZIEMER: I think we have to 

9 
 help the Board with whatever comments the 

10 Board is going to make. 

11 
 David actually had drafted some 

12 
 sort of straw men comments which I think will 

13 
 have to await the review of this, David, 

14 
 until, you know, but I think that's the nature 

15 
 of what we would do, because I think our 

16 
 Board, the full Board, is going to depend on 

17 
 us coming to them with a recommendation as to 

18 what the action should be. 

19 
 So, we can do the - we could 

20 
 develop the recommendation and wordsmith it 

21 
 and get it ready for eventual adoption, but it 

22 
 seems to me we're going to have to await the 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

123 

1 
 outside review. 

2 
 Because perception-wise for this to 

3 
 look like some sort of independent consensus 

4 
 in a sense, I mean, it would be different if 

5 
 an international group or NCRP had come out 

6 
 with some - that you guys are ahead of them on 

7 
 this, it appears to me, and there's even the 

8 
 possibility that they would end up adopting 

9 
 whatever the endpoint is here. 

10 
 But in any event, if we have good 

11 
 external reviewers that are seen by the public 

12 
 as not having a vested interest in the outcome 

13 would be very important. 

14 
 People of recognized stature, it's 

15 
 true you have to pay them a stipend. But I 

16 
 think even on the CLL thing, we had different 

17 
 views on that. And then we made a decision, 

18 
 but we want to get the pros and cons on this 

19 and then go from there. 

20 
 I mean, even SENES will be seen as 

21 
 having a vested interest here because you guys 

22 
 have a contract to do this and, you know. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

124 

1 
 People, their perceptions are you're getting 

2 
 paid to produce what the government wants. 

3 
 I mean, that's how people look at 

4 
 these things. We see that all the time. So, 

5 
 we get these independent reviews and we can go 

6 
 from there. 

7 
 David, I wasn't trying to preempt 

8 
 you, because you've done a straw man thing 

9 
 which I think is the sort of thing we need to 

10 
 provide for the Board in fleshing out the 

11 detail. 

12 
 This is much more complex than I 

13 
 anticipated it was going to be at the front 

14 end. 

15 
 CHAIRMAN RICHARDSON: Yes, the task 

16 
 that you suggested, I think we'll end up 

17 
 having to do of when NIOSH makes their - or 

18 
 puts forward something to be able to comment 

19 
 on. And I think it would be very useful to be 

20 
 able to comment on it and the reviewers' 

21 
 comments as well. 

22 
 That's sort of - it makes it 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

125 

1 
 somewhat unusual for the kind of list of 

2 
 issues that the Work Group has before it, 

3 
 because it's something that NIOSH is moving on 

4 
 independently and is relatively far ahead on. 

5 
 But the, you know, when we started 

6 
 out laying our scope of task, it was to 

7 
 identify issues that would be impacting the 

8 
 risk models and suggest or raise questions 

9 
 that would be kind of at least necessary to 

10 
 think about for moving forward on the issues 

11 
 and report just back the status of these 

12 scientific issues. 

13 
 It would be possible for us to do 

14 
 that in sort of a modest scope, or we can hold 

15 
 off and sort of table the issue and wait for 

16 
 NIOSH to put forward their opinion. So, that 

17 would be either. 

18 
 I mean, many of the issues that I 

19 
 think in the long run we'll be dealing with 

20 are not going to be like this. 

21 MEMBER MUNN: I should hope not. 

22 
 CHAIRMAN RICHARDSON: But like this 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

126 

1 
 in a sense that NIOSH may be considering or 

2 
 reacting on it while this Work Group is really 

3 
 not supposed to be - I don't think is supposed 

4 
 to be proposing distributions or something 

5 
 like that for parameters that NIOSH uses, but 

6 
 rather kind of looking at broader issues. 

7 
 MR. KATZ: Yes, I mean, David, I 

8 
 mean, I think the Work Group is free to 

9 
 comment as it will. I mean, it sounds like 

10 
 the comment on technical matters really needs 

11 to await the peer review and so on. 

12 
 But to the extent that there are 

13 
 already points of view or whatever that they 

14 
 should take into account before sending it off 

15 
 to the peer reviewers, I mean, I think that 

16 would be valuable. 

17 
 So, I don't think the Work Group is 

18 
 restrained or the Members from providing 

19 
 whatever kind of comments they might - or 

20 point of views they might have up front here. 

21 
 MEMBER MUNN: But by the same token, 

22 
 it's sometimes wise for groups especially like 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

127 

1 
 this Work Group, I think, to take a step back 

2 
 and reevaluate precisely what our 

3 
 responsibilities are in this regard. 

4 
 It's not our responsibility to 

5 
 identify the science, I think. I haven't seen 

6 
 any indication of that in our instructions. 

7 
 CHAIRMAN RICHARDSON: To identify 

8 
 the science, did you say? 

9 
 MEMBER MUNN: Yes. It is -- I 

10 
 believe our responsibility is to assure that 

11 
 the agency is performing the best science 

12 
 available in their activities, and our 

13 
 oversight role is one of oversight as I have 

14 interpreted it. 

15 
 Perhaps my interpretation is 

16 
 simplistic. But if that's the case, then the 

17 
 results of the developments in science that 

18 
 occur during the period of time that this 

19 
 program is operable may have results that a 

20 
 Work Group such as this one probably should 

21 
 consider in our deliberations before we go too 

22 
 far in our involvement in the development of 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

128 

1 
 the science itself. 

2 
 CHAIRMAN RICHARDSON: I guess I have 

3 
 a different view of that. I think the Science 

4 
 Issues Work Group has a responsibility for 

5 
 identifying scientific or technical issues 

6 
 that impact on the risk models. 

7 
 So we do, we should identify where 

8 
 we think there are either issues that relate 

9 
 to validity, clarity or the scientific basis 

10 
 for the compensation decisions that come 

11 through the program. 

12 
 MEMBER MUNN: Well, yes, I don't see 

13 that as conflict with what I said, David. 

14 
 CHAIRMAN RICHARDSON: Okay. Maybe I 

15 wasn't understanding you. 

16 
 MEMBER MUNN: No, no. I'm just 

17 saying -

18 
 DR. KOCHER: You're not wanting to 

19 
 tell NIOSH which data set they should use to 

20 solve a problem. 

21 
 MEMBER MUNN: Exactly. Exactly. 

22 
 But I certainly think that we are charged with 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

129 

1 
 the responsibility of taking a look at it and 

2 
 saying, yes, this is good science. 

3 
 CHAIRMAN RICHARDSON: Right. So, 

4 
 this is where kind of going back to the 

5 
 slides, the very early slides that showed 

6 
 what's currently done with IREP. There's a 

7 
 flow diagram, and then there's a set of 

8 
 histograms. 

9 
 And where I, you know, what's sort 

10 
 of been discussed right now relates to the 

11 histogram. 

12 
 I find the whole thing a little bit 

13 
 mind-boggling, the flow diagram and kind of 

14 
 the - I find that there's a level of 

15 
 complexity there and a set of varied 

16 
 assumptions. And then a lot of judgment that 

17 
 to me if I was going to point to NIOSH about 

18 
 places to think about this aspect of the 

19 
 compensation program, I would say this - I 

20 find this unsettling. 

21 
 I mean, it's not that it's unique. 

22 
 There are other organizations which have made 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

130 

1 
 a set of similar assumptions, but there - I 

2 
 mean, it's, you know, as the kind of 

3 
 justification, well, this histogram was drawn 

4 
 by Ethel Gilbert based on her judgment about 

5 
 those parameters, it's broken out for some 

6 
 disease entities and not others, you know, 

7 
 there's a whole series of things here which I, 

8 
 you know, I think we might want to think about 

9 
 as pointing out as technical issues. 

10 
 At least I would. I would lay on 

11 
 the table as a series of issues moving through 

12 the whole flow diagram. 

13 
 MEMBER MUNN: Certainly anytime we 

14 
 address something like as complex as IREP, we 

15 
 are going to be faced with innumerable 

16 
 technical conflicts both in terms of opinion 

17 and in terms of what data is reliable. 

18 
 That's one of the reasons why I 

19 
 said it is more of a burden than I believe 

20 
 could be intended for the Work Group or even 

21 for the Board to undertake to -

22 
 CHAIRMAN RICHARDSON: But IREP is, 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

131 

1 
 in fact, far less complicated than a lot of 

2 
 the dose reconstruction that's going on. I 

3 
 mean, it's the application of a set of risk 

4 
 coefficients and a few modifying parameters. 

5 
 I mean, we're working with lots of 

6 
 technical issues that are -- in which we 

7 
 evaluate uncertain scientists -- science with 

8 
 the reliance on subjectivity for, I mean, for 

9 
 lots and lots of aspects of the exposure 

10 
 reconstruction program that's going on. And 

11 this is another one of those. 

12 
 MEMBER ROESSLER: As a Work Group 

13 
 Member -- well, what David said about this 

14 being mind-boggling really hit home. 

15 
 But I think as a Work Group Member 

16 
 myself, I don't have the time and I don't have 

17 
 the expertise to go into all the details of 

18 
 this. But I think as Work Group Members, we 

19 
 can evaluate the experts that NIOSH selects 

20 and that's where I think we weigh in. 

21 
 If we have confidence in the 

22 
 experts who will put in the time and we know 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

132 

1 
 they have the expertise, I think that's a big 

2 
 factor. 

3 
 MEMBER MUNN: It would be. 

4 
 MEMBER ZIEMER: Dave, another 

5 
 comment. It seems - this is Ziemer. I think 

6 
 it would be appropriate for the Work Group to 

7 
 report to the Board some, in a preliminary 

8 
 way, number one, that we've reviewed the 

9 
 current use of the DDREF in the IREP model 

10 
 with the help of SENES and the NIOSH staff; 

11 
 number two, that we're aware that there's a 

12 
 lot of new biological data out there that 

13 
 SENES has been evaluating it and they are 

14 
 preparing a report for NIOSH and perhaps 

15 
 indicate that, and this could be a Work Group 

16 
 conclusion that, for example, that we agree 

17 
 that these parameters need an update - or not 

18 
 an update, but need a closer look for 

19 
 potential update and modification of the IREP 

20 
 model and that we agree with the direction 

21 
 being taken here. Which is to have the 

22 
 review, to have it independently evaluated, 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

133 

1 
 and then to have the opportunity to look at 

2 
 the potential changes. Something along those 

3 
 lines. 

4 
 I think we do owe the Board some 

5 
 sort of status information on what we're doing 

6 
 with this. 

7 
 CHAIRMAN RICHARDSON: Yes, I think 

8 
 that sounds reasonable. 

9 
 MEMBER ZIEMER: We don't have to 

10 
 reach any conclusion at this point other than 

11 
 to say we recognize that here's what's being 

12 
 done now, and there's a lot of new biology 

13 
 that could impact on this. Not that it 

14 
 necessarily will, but that it may or something 

15 along those lines. 

16 
 We can't reach a conclusion at this 

17 point in any event. 

18 
 CHAIRMAN RICHARDSON: I would like 

19 
 to reserve the -- kind of the option or the 

20 
 opportunity that this Work Group does -

21 
 expects at some point that it will tackle 

22 
 issues that are difficult that may require 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

134 

1 
 time or resources. 

2 
 I feel hesitant to say, well, these 

3 
 aspects of the program are complicated and 

4 
 technical and we can't be expected to dig into 

5 
 them. They're as technical and complicated, 

6 
 from my perspective at least, as much of the 

7 
 other exposure reconstruction and other 

8 
 aspects of the program. 

9 
 And I guess coming onto the Board, 

10 
 I felt like there were a number of technical 

11 
 issues that relate to this side of the program 

12 
 that are, you know, haven't been given nearly 

13 
 the attention that the exposure reconstruction 

14 
 aspects have, and yet, are part of the program 

15 
 and will take some time to get up to speed on, 

16 but are really important as well. 

17 
 MEMBER MUNN: David, I think you're 

18 
 amplifying what I was trying to say earlier 

19 
 and perhaps did not say in a very concise 

20 
 manner. 

21 Really, what I was trying to say 

22 
 is, first, my apologies for not having been on 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

135 

1 
 the teleconference when you were making an 

2 
 effort to set the Work Group up. I was 

3 
 traveling and was on airplanes at the time. 

4 
 But it - there's some question in 

5 
 my mind as to whether we as a Work Group have 

6 
 adequately defined our charge ourselves. And 

7 
 I didn't see just reading quickly through the 

8 
 transcript, I didn't see that the conversation 

9 
 that was had came to a logical conclusion in 

10 that regard. 

11 
 And I think perhaps you and I are 

12 
 saying very much the same kind of thing, 

13 
 except that I'm asking that the Work Group 

14 
 perhaps devote some time before we go too much 

15 
 further with very many of these scientific 

16 
 issues in better defining for ourselves 

17 
 exactly what our responsibility, what our 

18 
 charter is, and what our boundaries are going 

19 
 to be with respect to how we address these 

20 
 issues that have been placed before us as 

21 starting points. 

22 
 I don't know whether today is the 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

136 

1 
 appropriate day to do that, but it would be 

2 
 worthwhile from my point of view if we did 

3 
 spend some time trying to be very clear with 

4 
 each other about what our responsibilities are 

5 
 and how we're going to address those. 

6 
 CHAIRMAN RICHARDSON: Yes, we had 

7 
 some discussion of that the first time, and I 

8 
 think it would be worthwhile to kind of go 

9 
 back and review those. We had talked about 

10 
 some issues regarding scope and kind of 

11 
 process and deliverables and how that would 

12 happen. 

13 
 Maybe we should set some time at 

14 
 the start of our next meeting to revisit 

15 
 those, and maybe I can circulate something 

16 
 ahead of time as kind of a starting point for 

17 that discussion. 

18 
 MEMBER MUNN: I think that would be 

19 
 wise. It would be very helpful from my 

20 
 perspective to have the views of the other 

21 
 Members of this Working Group as to how they 

22 
 perceive their responsibility on this group to 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

137 

1 
 be. 

2 
 Yes, I would like very much if we 

3 
 would set aside some time at the beginning of 

4 
 our next session to do that and perhaps even 

5 
 have some exchanges by email and try to come 

6 
 to some general conclusion with respect to 

7 
 limitations of what our expectations are and 

8 
 what the Board's expectations are of us. 

9 
 MEMBER ZIEMER: One of the 

10 
 philosophical things I think might be worth 

11 
 discussing is the issue of use of current 

12 
 science and what happens when it changes. And 

13 this is a practical thing. 

14 
 For example, when we change a 

15 
 method of reconstructing dose, and there I'm 

16 
 talking about some usually modeling where 

17 
 NIOSH has some early models, and then there's 

18 
 - and we have some sites that are in this 

19 
 category now where the models get changed 

20 
 simply because we get new information about 

21 the site and that sort of thing. 

22 
 But here if the science changes, 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

138 

1 
 for example, a dose-rate factor changes this 

2 
 issue, and I'm not sure how the regs read or 

3 
 the legal ramifications, but does it mean you 

4 
 go all the way back to ten years or 15 years 

5 
 where you were using the best science at the 

6 
 time? Because science is always going to 

7 
 change. 

8 
 Ted, you might help us out, but one 

9 
 of the things that is sort of a concern is 

10 
 that do you go back and redo everything that 

11 
 you've done for a decade because the science 

12 has changed. 

13 
 MR. KATZ: And to speak on that 

14 
 point, and we wrote the regs with an eye to 

15 
 the fact that the science would change and to 

16 
 accommodate that by, whenever necessary, 

17 
 because the science dictates better methods, 

18 incorporating those new methods. 

19 
 And integral to that is that cases 

20 
 that were already completed that would be 

21 
 affected by those improvements, would take 

22 
 into account those improvements that would be 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

139 

1 
 affected. 

2 
 I mean, honestly for cases that are 

3 
 already compensated, it's a nonissue. But for 

4 
 cases that are not compensated -

5 
 MEMBER ROESSLER: Not to reverse -

6 
 MEMBER ZIEMER: Well, you can't 

7 
 reverse. 

8 
 MR. KATZ: No, there's no reversing 

9 
 cases that are compensated. But I'm saying 

10 for cases that are not compensated --

11 (Simultaneous speaking.) 

12 
 MR. KATZ: -- better science would 

13 
 be employed again if it would affect their 

14 results. 

15 
 DR. NETON: And since DDREF is in 

16 every single case -

17 
 MEMBER ZIEMER: Well, that's exactly 

18 
 my point. And then ten years from now you'll 

19 have something else -

20 
 MR. KATZ: That's an argument for 

21 
 taking due diligence in revising the science, 

22 
 I think. It's not a question of whether the 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

140 

1 
 science should be revised when it should be, 

2 
 but it just is an argument for doing this in a 

3 
 very deliberate, diligent way. 

4 
 DR. MAURO: This is John Mauro. I 

5 
 also have an observation that I'd like to put 

6 
 out. The DDREF operates off the excess 

7 
 relative risk, which is really the rock that 

8 
 IREP stands on. And I realize SC&A does not 

9 
 get involved in reviewing any IREP work, but 

10 
 I'm on the phone and I'm listening and I'm 

11 
 very interested with a strong background in 

12 radiobiology. 

13 
 If the day comes when a judgment is 

14 
 made that some change will be made to the 

15 
 distribution for the DDREF and incorporate it 

16 
 into IREP, I would say the only caution I 

17 
 would advise is that that be done in concert 

18 
 with any consideration on the excess relative 

19 
 risk, which is even more fundamental and which 

20 
 is also a subject undergoing considerable 

21 reevaluation. 

22 
 They sort of go hand in hand and 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

141 

1 
 you really wouldn't do one without the other. 

2 
 DR. NETON: You raise a good point, 

3 
 John. This is Jim. But there's a continuing 

4 
 dilemma as to where you draw the line in the 

5 
 sand and move forward. 

6 
 I mean, we've talked about this in 

7 
 the past and -

8 
 MEMBER ZIEMER: Or do you wait for 

9 
 something to -

10 DR. NETON: Do you wait for 

11 
 something else to catch up? And then all of a 

12 
 sudden, as you saw, the change between our 

13 
 2009 concept that SENES has outlined versus 

14 the one today is even different. 

15 
 So I don't know how you 

16 
 realistically do it all at one time. It just 

17 
 would be very difficult because the data 

18 
 aren't available all at the same time. But 

19 you raise a very - that's a very good point. 

20 
 MEMBER MUNN: Well, since we have no 

21 
 sunset clause for the operations that we're 

22 
 involved in here, one can question how long we 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

142 

1 
 wait for the science to mature and change. 

2 
 I'm not sure science ever matures, 

3 
 but as it changes as we go -

4 
 DR. NETON: It's a little different 

5 
 with this particular issue because it was sort 

6 
 of an in-house developed science -

7 
 MEMBER MUNN: Yes, it is. 

8 
 DR. NETON: -- that is commenting 

9 
 on the change versus something that's, in my 

10 
 mind, a little more clear-cut if you have a 

11 
 new ICRP lung model that came out, for 

12 example. 

13 
 And we would probably adopt that 

14 
 fairly readily because it's consensus science 

15 
 and it's put out there for general use. This 

16 is a little different. 

17 
 MEMBER MUNN: It is. 

18 
 DR. NETON: That's why we're moving 

19 
 cautiously, but I think the plan is valid to 

20 
 move forward with a review by experts and see 

21 where they land. 

22 
 But I don't disagree with David 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

143 

1 
 Richardson though. We would welcome any 

2 
 general comments on the DDREF itself and its 

3 
 employment in the program. I mean, that's 

4 
 certainly fair game for, I think, the Working 

5 
 Group. 

6 
 CHAIRMAN RICHARDSON: Well, thank 

7 
 you very much for the presentation. I didn't 

8 
 say that at the start, but it was really very 

9 
 useful for me in understanding both what's 

10 
 been done and to kind of hear about the review 

11 that you've undertaken. 

12 
 And I think a lot of the points in 

13 
 your conclusion correspond to some of the 

14 
 streamlining that I was imagining and hoping 

15 
 that NIOSH will take both in kind of trying to 

16 
 lean more on an empirical basis for the 

17 
 distribution for this factor - I think the 

18 
 idea of stepping away from separate 

19 
 distributions for different tissues is 

20 probably a sensible one. 

21 
 I appreciated the way that you 

22 
 handled a number of the points as I tried to 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

144 

1 
 in my own thinking, kind of separate out low2 
 LET from high-LET radiation. 

3 
 It's still not quite clear to me 

4 
 what I - the point that you made, I believe, 

5 
 is that the inverse exposure rate effect, 

6 
 which in my world would be a dose-rate 

7 
 effectiveness factor, is, in fact, 

8 
 incorporated into IREP someplace else; is that 

9 
 correct? 

10 DR. TRABALKA: Within the radiation 

11 effectiveness factor, yes. 

12 
 CHAIRMAN RICHARDSON: Which is 

13 
 interesting why that's the way it is, I guess, 

14 
 but it is there. Because there's right at -

15 
 if I look at this flow chart, you're implying 

16 
 full certainty about the dose-rate 

17 
 effectiveness of high-LET radiation. But what 

18 
 you're saying is that there's a distribution 

19 someplace else capturing that side of the -

20 
 DR. HOFFMAN: Yes, there is quite an 

21 
 important distribution associated with the 

22 
 uncertainty and what's called the radiation 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

145 

1 
 effectiveness factor. 

2 
 And especially as that is applied 

3 
 to high-LET radiation, namely neutrons and 

4 
 alpha radiation, both neutrons and alpha 

5 
 radiation have this inverse dose-rate 

6 
 adjustment. 

7 
 CHAIRMAN RICHARDSON: Which is a 

8 
 DDREF less than one. 

9 
 DR. HOFFMAN: Yes. 

10 
 DR. NETON: At what point does that 

11 kick in though? It's pretty high. The dose? 

12 
 DR. KOCHER: No, it's always there. 

13 
 Certainly for alpha particles it's always 

14 
 there. For neutrons, I have to go back and 

15 think about it. 

16 
 DR. NETON: Even for very small 

17 alpha doses? 

18 
 DR. KOCHER: Yes, see, I argued that 

19 it shouldn't be in there, but I lost. 

20 
 DR. NETON: I don't remember that 

21 
 argument. 

22 DR. KOCHER: Yes, I do. You and I 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

146 

1 
 had at it. 

2 
 CHAIRMAN RICHARDSON: As long as 

3 
 this is a topic, at some point it may be 

4 
 something that I guess I would suggest again 

5 
 the Work Group may want to think about. 

6 
 Because it would fall - for me, it falls under 

7 
 the rubric of a dose-rate effectiveness 

8 
 factor, and it's fine for us to start by 

9 
 looking at low-LET radiation. 

10 
 But if there's been apparent 

11 
 disagreement among the people in the room 

12 
 about how it's implemented for high-LET 

13 
 radiation, then I think this is where there is 

14 
 probably, I don't know, BEIR VI, for example, 

15 
 has a strong opinion about high-LET radiation 

16 
 and inverse exposure rate effects. So it 

17 might be worth us at least -

18 
 DR. KOCHER: Let me clarify the 

19 
 situation for neutrons since we raised it. 

20 
 This inverse dose-rate effect is applied only 

21 
 in cases of chronic exposure to neutrons. The 

22 
 acute dose response is assumed to be linear at 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

147 

1 
 any dose. So that's how it differs from the 

2 
 low-LET. 

3 
 For alpha particles, the inverse 

4 
 dose-rate effect is always applied because all 

5 
 the internal exposures, the alpha emitters, 

6 
 are assumed to be chronic, reasonably enough. 

7 
 So it's always in there. 

8 
 And you and I had an argument about 

9 
 whether it should be in there, and I lost. 

10 
 DR. NETON: I completely forgot 

11 that. 

12 
 DR. KOCHER: Well, over lunch or at 

13 a meeting this afternoon we can revisit that. 

14 
 DR. NETON: That's fine. Because my 

15 
 thinking was as long as we're talking on this 

16 
 subject, the DDREF is built into the 

17 
 calculation for excess relative risk for 

18 alphas. 

19 
 DR. KOCHER: That's to adjust the 

20 photon risk. 

21 
 DR. NETON: Right, adjust the photon 

22 
 risk. Because we have gone - it was my 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

148 

1 
 thinking early on that the change in DDREF 

2 
 would not affect many of our cases because we 

3 
 don't have very high external exposures, as we 

4 
 talked about when the meeting started, except 

5 
 in the very early years. 

6 
 But what happened since that DDREF 

7 
 is built into the adjustment of the photon 

8 
 dose when you have an REF for alphas, we have 

9 
 - as a major effect, we've done some analyses 

10 
 internally that will majorly affect people 

11 
 with exposures to alpha, which is probably the 

12 
 majority - a large majority of our cases have 

13 
 exposures to plutonium, uranium. Those are 

14 
 the cases that have high PC values, and it's 

15 going to affect those. 

16 
 And it was a surprise to me to find 

17 
 that out that this DDREF embedded in the 

18 
 adjustment factor because of the way the REF 

19 
 was developed. So it's not really accurate to 

20 
 say that the DDREF does not affect high-LET 

21 radiation, especially alpha - it does. 

22 
 DR. KOCHER: It affects alpha 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

149 

1 
 particles but not -

2 
 DR. NETON: As much. At least from 

3 
 our analysis, that's true. 

4 
 MEMBER ROESSLER: Perhaps the Work 

5 
 Group needs a little review of the REF. 

6 
 Because I'm thinking back to that, and what 

7 
 you've just said, yes, that's an impact and I 

8 
 think we need to look at that. 

9 
 DR. NETON: That would be an 

10 
 interesting - I don't think we've ever gone 

11 over it with the - actually, we have. 

12 
 MEMBER ROESSLER: He did a 

13 presentation. 

14 
 DR. KOCHER: There were two 

15 presentations to the Board -

16 DR. NETON: Early on. 

17 
 MEMBER ROESSLER: But we weren't 

18 thinking -

19 DR. KOCHER: Well, it was all new. 

20 
 MEMBER ROESSLER: Yes, yes. And we 

21 weren't thinking of the impact that -

22 (Simultaneous speaking.) 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

 

150 

1 
 DR. KOCHER: - snowstorm. 

2 
 MEMBER ZIEMER: Well, as a minimum 

3 
 I'm wondering if we could revisit that and 

4 
 just update our own memories on that. I don't 

5 
 recall the details of it at all. 

6 
 MEMBER ROESSLER: I mean, that's a 

7 
 publication, but it's pretty hard to get 

8 
 through. It's pretty heavy stuff. 

9 
 MEMBER MUNN: Yes. 

10 DR. TRABALKA: Well, if I -

11 (Simultaneous speaking.) 

12 
 DR. TRABALKA: -- longer and less 

13 dense. 

14 
 MEMBER ROESSLER: It was easier to 

15 understand when he presented it in person. 

16 
 MEMBER MUNN: A man after my own 

17 heart. 

18 
 DR. NETON: Well, we certainly would 

19 
 not be against having a presentation in the 

20 future as long as we can get SENES -

21 
 DR. TRABALKA: That's something we 

22 can talk about this afternoon, if you want. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

151 

1 
 DR. NETON: Yes. And it is, in my 

2 
 opinion, integral to the DDREF issue because 

3 
 of this incorporation of it into the 

4 
 adjustment of the photon risk model -

5 
 (Simultaneous speaking.) 

6 
 MEMBER ROESSLER: It appears to be. 

7 
 DR. NETON: Well, yes. I mean, this 

8 
 equation -

9 
 MEMBER ROESSLER: How can you -

10 
 DR. NETON: To prepare for the 

11 
 meeting, Daniel and I were going over the 

12 
 Health Physics publication. Which, by the 

13 
 way, if anybody doesn't have a copy of this 

14 
 special edition that we put out, we have about 

15 300 in the closet back at work. 

16 
 DR. KOCHER: Please take one. 

17 
 DR. NETON: Please take several. 

18 
 But specifically Equation 26 in that article 

19 
 is the one I'm talking about with the 

20 
 adjustment. And it's pretty clear. And 

21 
 that's why we ended up testing, Daniel with 

22 Iulian and -

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

152 

1 
 CHAIRMAN RICHARDSON: Now, for alpha 

2 
 particles and neutrons, let's set this aside 

3 
 and say for neutrons, the DDREF for neutrons 

4 
 applies to both acute and chronic neutron 

5 
 exposures? Was that what you said? But at 

6 
 different threshold levels? 

7 
 DR. KOCHER: No, the dose response 

8 
 for acute exposure to neutrons is assumed to 

9 
 be linear with no adjustment at any dose. The 

10 
 inverse dose-rate effect is applied to neutron 

11 exposures only in case of chronic exposure. 

12 
 DR. HOFFMAN: And DDREF is not 

13 applied at all for neutrons. 

14 
 DR. KOCHER: The way this separation 

15 
 that you pointed out has been made, there's no 

16 
 DDREF anywhere for neutrons. But there is 

17 
 this inverse dose-rate effect that's embedded 

18 
 in the REF for neutrons that's applied to 

19 
 chronic exposure only. And for alpha 

20 
 particles, the inverse - there is no DDREF for 

21 alpha particles, per se. 

22 
 CHAIRMAN RICHARDSON: So there 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

153 

1 
 you've made a distinction between the shape of 

2 
 the exposure response relationship for 

3 
 neutrons and the effect of inverse exposure 

4 
 rate effects, the protraction effect of the 

5 
 exposure. 

6 
 And you've said that the energy 

7 
 deposition for neutrons results in cancer 

8 
 risks which are proportional to dose and 

9 
 they're linear on an excess relative risk 

10 scale. 

11 
 But when there's protraction, the 

12 effect varies; is that right? 

13 
 DR. KOCHER: When it's protracted, 

14 
 it basically changes the slope of the entire 

15 
 dose response for chronic exposure. It just 

16 
 shifts the slope because it's applied 

17 independent of dose for chronic exposure. 

18 
 The same distribution applies at 

19 
 any dose. It's a little different than this 

20 
 phasing in of the DDREF for the low-LET. It's 

21 
 just a single correction that's applied to any 

22 
 dose as long as the exposure is chronic or 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

154 

1 
 protracted. So you're just changing the slope 

2 
 of the linear dose response, basically. 

3 
 CHAIRMAN RICHARDSON: And someone 

4 
 characterized what the recent UNSCEAR report 

5 
 did for solid cancers with exposure to low-LET 

6 
 radiation, which was they said, well, with the 

7 
 cancer incidence data the effect looks 

8 
 proportional to dose. The shape of the 

9 
 exposure response is well-modeled by a linear 

10 model. 

11 
 And that, I mean, I don't want to 

12 
 go too far there except to say it remains for 

13 
 my thinking that what's been done, for 

14 
 example, in modeling the effects of inhalation 

15 
 of radon and other places, is to separate out 

16 
 the question of the shape of the exposure 

17 
 response function from the effect of 

18 protraction or the exposure rate effect. 

19 
 And that's - there's a lot of 

20 clarity to be gained there. 

21 
 DR. KOCHER: You can't do that for 

22 
 radon because there's no such thing as an 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

155 

1 
 acute exposure. 

2 
 CHAIRMAN RICHARDSON: They've 

3 
 modeled the shape of the exposure response 

4 
 function and the exposure rate effect. 

5 
 DR. KOCHER: Yes, based on an 

6 
 observation in some studies that the risk was 

7 
 higher the lower the dose rate at the same 

8 
 dose. 

9 
 CHAIRMAN RICHARDSON: Yes, exactly. 

10 
 DR. KOCHER: But the difference 

11 
 between radon and gamma rays is you don't have 

12 acute exposure to radon. 

13 
 CHAIRMAN RICHARDSON: I mean, we 

14 
 talked through the experimental setups in 

15 
 which you could consider the effect of 

16 different types of dosing experiments, right? 

17 
 And all of those thought 

18 
 experiments involved separating out the shape 

19 
 of the exposure response function from 

20 
 separating out questions about the effect of 

21 protraction. 

22 
 We're all aware of the effects of 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

156 

1 
 priming exposures, for example in 

2 
 radiotherapy, in which the response is 

3 
 mitigated by fractionating the exposure and 

4 
 giving the priming dose. 

5 
 That would be an example where even 

6 
 if we're talking about leukemia, as I read it, 

7 
 the shape of the exposure response may be 

8 
 linear quadratic. And yet, a priming dose, 

9 
 fractionation or delivering the same total 

10 
 dose over periods, is going to yield a 

11 different response. 

12 
 The argument that they're somehow 

13 
 intimately embedded by the linear quadratic 

14 
 shape of an exposure response function for a 

15 
 single exposure doesn't conform to 

16 experimental evidence in medical practice. 

17 
 So I'm sort of looking at like a 

18 
 lot of complexity laid out in this flow 

19 
 diagram for scenarios where I would think we 

20 
 could question a series of these decision 

21 
 points. And I think what's been done has 

22 started to simplify them, but it's -

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

157 

1 
 DR. KOCHER: Yes, my reaction to 

2 
 your comment about the flow diagrams is that I 

3 
 suspect it's fairly transparent what has been 

4 
 done if you stare at the flow diagram for a 

5 
 little while because there's not that many 

6 
 decision points. But what you're raising is 

7 
 certainly something that we would be 

8 
 interested in knowing more about, and that is 

9 
 problems that you have with these decision 

10 points and how they're made. 

11 
 That's a whole other area that if 

12 
 you have different thoughts about the validity 

13 
 of these decision points, I suspect NIOSH 

14 would like to hear about that. 

15 
 MEMBER ZIEMER: All you're saying is 

16 this is what you're doing now. 

17 DR. KOCHER: Yes. 

18 
 MEMBER ZIEMER: So the interesting 

19 
 question is what would the decision points 

20 
 look like in your new proposal, and are they 

21 the right ones? 

22 
 CHAIRMAN RICHARDSON: Right, yes. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

158 

1 
 No, I - yes, I agree. So it's great to know. 

2 
 I mean, as I said, there have been a series 

3 
 of these questions about what was currently 

4 
 being done that weren't as clear in my mind as 

5 
 they are now after your presentation. And I 

6 
 really appreciate that. And I'm still, I 

7 
 guess -

8 
 DR. KOCHER: Your comment about 

9 
 leukemia I thought was also well-taken. My 

10 
 sense is that, okay, we have a linear 

11 
 quadratic model in IREP for acute exposure. 

12 
 And the assumption that only the linear term 

13 
 applies in cases of chronic exposure, that's 

14 
 probably a judgment. 

15 
 I doubt that that's written in 

16 
 concrete somewhere. Charles might disagree 

17 
 with me, but I suspect that falls in the 

18 
 rubric of an assumption. 

19 
 MEMBER ZIEMER: Have you thought 

20 
 about a similar diagram for the new things 

21 
 you're proposing or -

22 
 DR. APOSTOAEI: This is Iulian 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

159 

1 
 speaking. One point that will change in the 

2 
 flow diagram is that we will have the same 

3 
 distribution and be applicable for all solid 

4 
 tumors. So that decision point to separate 

5 
 thyroid and breast will go away. So, that's 

6 
 one example and -

7 
 DR. NETON: The histogram goes away. 

8 
 I mean, it's a continuous function, right? 

9 
 DR. APOSTOAEI: Right. So, but we 

10 
 have two distributions; now we're going to 

11 have just one. 

12 
 DR. HOFFMAN: We'll have one 

13 
 distribution also where we are proposing 

14 
 different ranges for the definition of what 

15 
 should be considered a lower bound for the 

16 
 acute dose. That would determine when a DDREF 

17 needs to be considered for acute exposures. 

18 
 DR. KOCHER: Other than that change, 

19 
 it really - I don't think we've thought about 

20 any changes in the decision diagram, per se. 

21 
 MEMBER ZIEMER: You're proposing ten 

22 
 millisieverts when you lower the bar. And 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

160 

1 
 it's currently 30, okay. 

2 
 CHAIRMAN RICHARDSON: You know, as 

3 
 the histogram you're imagining becomes - has 

4 
 more mass at one -

5 
 DR. HOFFMAN: Yes, and it becomes 

6 
 essentially a piece-wise uniform distribution, 

7 
 continuous. And the reason for this is that 

8 
 numerous data sets that are then weighted in 

9 
 terms of degrees of plausibility are then 

10 combined. 

11 
 And so the final state of knowledge 

12 
 of distribution that we are recommending that 

13 
 replace these histograms, is a continuous 

14 
 distribution, but it can only be approximated 

15 
 by the - it is not exactly - does it conform 

16 to a named statistical distribution. 

17 
 CHAIRMAN RICHARDSON: Right. I'm 

18 
 imagining though -- so we've got a decision 

19 
 point here with - you've got on the left and 

20 
 right-hand side of this figure - on the right21 
 hand side of the flow diagram, there's a 

22 
 complicated function which moves you from one 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

161 

1 
 to a distribution which you're imagining which 

2 
 has mass - the majority of its mass around 

3 
 one. 

4 
 And as you get to this threshold, 

5 
 you're smoothing the transition between a 

6 
 value of one and a value which has its modal 

7 
 value around one. So you're moving from 

8 
 certainty about the shape of the acute 

9 
 exposure response relationship -

10 DR. HOFFMAN: To uncertainty. 

11 
 CHAIRMAN RICHARDSON: -- to one 

12 where there is uncertainty about it. 

13 DR. HOFFMAN: Right. 

14 
 DR. KOCHER: Which increases as the 

15 dose goes down. 

16 
 CHAIRMAN RICHARDSON: Yes, but it's 

17 
 - it does that as a function of the magnitude 

18 of the acute dose. 

19 
 DR. HOFFMAN: Yes. 

20 
 CHAIRMAN RICHARDSON: So it's saying 

21 
 that's the - as you get into the low-dose 

22 
 range, there is greater uncertainty about the 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

162 

1 
 shape of the exposure response function. 

2 
 DR. HOFFMAN: Yes. 

3 
 CHAIRMAN RICHARDSON: Is that what 

4 
 you - maybe that is what you think of as the 

5 
 DDREF. 

6 
 DR. HOFFMAN: Well, the way you said 

7 
 it in plain English is exactly what's 

8 
 happening. As the acute dose decreases, the 

9 
 amount of uncertainty in the risk associated 

10 
 with that dose increases. But the central 

11 
 value, given our proposed revisions, would be 

12 
 closer to straight linearity or closer to a 

13 DDREF of 1.0 than it was previously. 

14 
 CHAIRMAN RICHARDSON: Right. I 

15 
 mean, previously as it got down there, you 

16 
 divided the linear excess relative rate model 

17 
 by a factor which had its modal value around 

18 1.5? 

19 DR. HOFFMAN: That's right. 

20 
 CHAIRMAN RICHARDSON: Which to me, 

21 
 was sort of, you know, it's surprising if you 

22 
 would say that to most people when they would 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

163 

1 
 be thinking about, you know, saying we're 

2 
 starting off with the assumption of a linear 

3 
 no-threshold model. And yet, implicit in this 

4 
 is that there's non-linearity. There's a 

5 
 curvature to the exposure response function as 

6 
 you get to lower doses. 

7 
 I guess one of the questions is we 

8 
 know there's uncertainty about the exposure 

9 
 response function as you get to lower doses. 

10 
 And why isn't that captured already by the 

11 variance of the risk estimates? 

12 
 Why are we adding another factor in 

13 
 to say that there's uncertainty of our 

14 essential estimates -

15 
 DR. KOCHER: The uncertainty in the 

16 
 ERR per sievert is independent of dose, is the 

17 
 reason why. If there were no DDREF, the 

18 
 uncertainty would - in the ERR would be 

19 independent of dose. 

20 
 CHAIRMAN RICHARDSON: So if you just 

21 
 wanted to answer that question, the best way 

22 
 to do it, the most logically coherent way to 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

164 

1 
 do it would be to derive point-wise confidence 

2 
 bounds using the lifespan data for the risk, 

3 
 for all the risk models. 

4 
 You already have - you have 

5 
 preferred data sets you want to use to derive 

6 
 the dose response coefficient, you've fitted a 

7 
 model to it, and now you want to reflect the 

8 
 fact that there's variance in a point-wise 

9 
 fashion as you're moving along in the model. 

10 
 So this would be like a very 

11 
 complicated exercise to get around to 

12 
 something - I'm not saying our best estimate 

13 
 is from the fitted model, but the uncertainty 

14 increases as you get to move along the datas. 

15 
 DR. KOCHER: The DDREF is really 

16 kind of an artificial construct that -

17 CHAIRMAN RICHARDSON: Absolutely. 

18 
 DR. KOCHER: -- attempts to make 

19 
 things a little easier, but of course it's a 

20 complicated problem. 

21 
 CHAIRMAN RICHARDSON: No, but if you 

22 
 would show this to somebody and they've got 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

165 

1 
 this weird assumption about a very complicated 

2 
 function smoothing in an uncertainty 

3 
 distribution that's going to move from one to 

4 
 a bound around one with a distribution that's 

5 
 going to be around modal and it's to capture 

6 
 uncertainty in the exposure response function 

7 
 at the lower doses where we've extrapolated to 

8 
 where all the exposure is occurring for the 

9 
 workers, then maybe what you just want to do 

10 
 is just take the point-wise confidence bounds 

11 
 from the data sets that the risk estimates are 

12 coming from. 

13 
 DR. KOCHER: So you would say that 

14 
 the ERR per sievert should have an uncertainty 

15 that's a function of dose? 

16 
 CHAIRMAN RICHARDSON: Well, you 

17 
 would use the empirical confidence bounds for 

18 
 the risk estimates. You're already doing 

19 
 that. I mean, you've already got one. You're 

20 just - it's not point-wise right now. 

21 
 I mean, I'm still, you know, I'm 

22 
 trying to work through what all is wrapped up 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

166 

1 
 in this. And there's a lot of things wrapped 

2 
 up in it. 

3 
 One of them is the shape of the 

4 
 exposure response function. One is the kind 

5 
 of confidence you have in the estimates in the 

6 
 low-dose range. And it's, I mean, I guess -

7 
 DR. HOFFMAN: Yes, I mean, if we 

8 
 were to think about a major revision to IREP, 

9 
 then there are several ways one could proceed. 

10 
 One is a revision update of DDREF and how it 

11 
 is applied to linear risk coefficients that 

12 
 have been published. Another is to forget the 

13 
 DDREF and apply confidence bounds to the 

14 
 epidemiological data as they are extrapolated 

15 
 down below limits of epidemiological 

16 detection. 

17 
 DR. TRABALKA: There's some 

18 
 extremely large uncertainties on low-dose 

19 data. 

20 
 CHAIRMAN RICHARDSON: Right. Well, 

21 
 I mean, that's - I'm just not - introducing a 

22 
 shape parameter as - which appears ad hoc, a 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

167 

1 
 dose limit which is some transition value, a 

2 
 complicated kind of logistic function, I 

3 
 guess, sort of shaped thing to smooth - to 

4 
 transition into that to capture the fact that 

5 
 we're uncertain about the low-dose risk 

6 
 coefficients. 

7 
 I mean, it seems to me like lots of 

8 
 parameters and decisions about parametric 

9 
 forms introduced - I mean, there's already - I 

10 
 mean, from my point of view the risk estimates 

11 
 are already highly imprecise. I'm not sure 

12 there's actually any value in any of it. 

13 
 You could just say, I mean, if you 

14 
 wanted to do that, you would say these risk 

15 
 estimates are - these are our best empirical 

16 
 risk estimates. We have a linear model that 

17 
 we fit to solid cancer data. It has an 

18 
 estimated variance around it which captures 

19 
 uncertainty, and it leverages some form of 

20 
 precision through the parametric assumption 

21 
 that as exposure increases, cancer risk 

22 increases. And that's the best we can do. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

168 

1 
 I think, I mean, from my point of 

2 
 view, that's what's done in epidemiology right 

3 
 now. 

4 
 DR. KOCHER: But yet all the 

5 
 published risk coefficients using a linear 

6 
 model are dose independent. 

7 
 CHAIRMAN RICHARDSON: No, what's 

8 
 done - exactly. What's done right now is you 

9 
 say the best we can do is to make a parametric 

10 
 assumption that cancer risk varies as a linear 

11 function of dose and we estimate it. 

12 
 And that's where we're leveraging 

13 
 our confidence. That's where we're leveraging 

14 
 the precision about the low-dose range is by 

15 
 the parametric assumption that there's a 

16 linear exposure response function. 

17 
 And that's, you know, so that's the 

18 
 best estimate. That's one simple parametric 

19 
 assumption. And what's being - if my 

20 
 characterization that moving from the left21 
 hand side to the right-hand side of this flow 

22 
 diagram is when we're going to - if we're 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

169 

1 
 going to have modal values centered around 

2 
 one, it's just adding in greater uncertainty 

3 
 about the low-dose range where you've just 

4 
 stepped away from the kind of, you know, the 

5 
 foundational kind of parametric assumption 

6 
 that we had that, well, we can get some sort 

7 
 of best estimate by just saying the risk - the 

8 
 average risk changes apportioned to the dose 

9 
 like we do with almost all risk assessments. 

10 
 DR. KOCHER: Well, it would be a way 

11 
 of representing greater uncertainty at the low 

12 doses where you really can't see anything. 

13 
 DR. TRABALKA: It would make 

14 
 adjustments based on DDREF look like pikers. 

15 
 Because, remember, the A-bomb survivor data 

16 
 and the risk coefficients in IREP, these are 

17 driven by doses between 0.5 and 4 gray. 

18 
 The question then becomes how does 

19 
 the risk change from the risk estimates made 

20 
 derived by the - apparently these higher 

21 doses, down at very low doses? 

22 
 And the only theoretical way to do 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

170 

1 
 that is to assume a linear quadratic model 

2 
 could be there in the data. It's just 

3 
 submerged in the uncertainty. 

4 
 It really should be a linear 

5 
 quadratic exponential model that covers the 

6 
 whole dose range, which adds even more 

7 
 uncertainty in the three parameters to deal 

8 
 with. Everything blows up. 

9 
 Right now the DDREF is probably the 

10 
 best we can do, and we simply don't have 

11 
 enough information to separate data on LDEFs 

12 
 and DREFs to do what you're suggesting, which 

13 
 would be excellent, you know, in your 

14 hypothetical approach here. 

15 
 But it's a compromise approach and 

16 
 there's no getting away from it, but that's 

17 just the state of our knowledge. 

18 
 MEMBER MUNN: The question is is it 

19 
 the best approach? That seems to me to be our 

20 
 responsibility as a Work Group. Is it the 

21 
 best we can do? Our only responsibility, as I 

22 
 see it, is to judge whether or not this is the 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

171 

1 
 best science available. 

2 
 DR. TRABALKA: And speaking for the 

3 
 SENES group, we would welcome any input on 

4 
 that topic and any specific comments you have 

5 
 on the report recognizing that people like 

6 
 professors are very, very busy and they don't 

7 
 have time to do all this, and others. 

8 
 MEMBER ROESSLER: Can I make a 

9 
 comment - two comments, actually. 

10 
 Jim Neton mentioned Equation 26 in 

11 
 the publication by NIOSH. And I just found it 

12 
 and I think everybody should look it up, 

13 because it very clearly -

14 DR. KOCHER: Also in the REF paper. 

15 
 MEMBER ROESSLER: That is the REF 

16 paper, I think. 

17 
 DR. KOCHER: No, that's the IREP 

18 
 paper. 

19 MEMBER ROESSLER: Yes, it very 

20 
 clearly shows the relationship between ERR, 

21 
 REF and DDREF in dose, weighting factors. 

22 It's just right there. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

172 

1 
 Now we know what the real impact is 

2 
 going to be, even on high-LET, which is - I'm 

3 
 glad David brought it up. 

4 
 The other thing I noticed when I 

5 
 was looking at that issue -

6 
 DR. KOCHER: The key is that 

7 
 Equation 26 applies to alpha particles as well 

8 
 as low-LET. So, you end up saying, I thought 

9 
 there was no DDREF for alpha particles, but 

10 this is a DDREF for photons. 

11 
 MEMBER ROESSLER: The other thing in 

12 
 that same issue and I haven't looked it up, is 

13 
 a paper by Paul Ziemer. And I haven't 

14 
 reviewed it, but maybe we should look at that 

15 on the responsibilities of the Board. 

16 
 And so, Wanda, you brought that up 

17 and we should maybe reread that. 

18 DR. NETON: Which paper, I'm sorry? 

19 
 MEMBER ROESSLER: The issue of the 

20 
 journal that you have there. There's a paper 

21 by Paul Ziemer talking about -

22 
 MEMBER ZIEMER: I don't remember it 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

173 

1 
 myself. 

2 
 DR. NETON: I remember it being in 

3 
 there. I haven't read it in a while -- oh, 

4 
 the responsibilities of the Advisory Board. 

5 
 MEMBER ROESSLER: Yes. 

6 
 DR. KOCHER: You make good points, 

7 
 David, but we're basically playing by the 

8 
 rules of the game as conventionally accepted 

9 
 today realizing that DDREF is an artificial 

10 
 construct that covers all kinds of sins. If 

11 you had the right -

12 
 MEMBER ZIEMER: Well, David may be 

13 
 saying, go and sin no more, I think is what he 

14 -

15 (Laughter.) 

16 
 DR. KOCHER: I mean, if you knew the 

17 
 correct dose response down to zero dose, you 

18 wouldn't use it. 

19 
 CHAIRMAN RICHARDSON: Well, one of 

20 
 my concerns is suppose we take the empirical 

21 
 data for solid cancers. We take the empirical 

22 
 data for the leukemia, we fit a model, we have 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

174 

1 
 a parametric model and we stop there. 

2 
 We take the empirical data for the 

3 
 solid cancers, we have a model which fits 

4 
 reasonably well, and we say, but under 

5 
 different exposure conditions, we think the 

6 
 data should look - should have curvature to 

7 
 it, and it doesn't. 

8 
 Then you were sort of, you know, 

9 
 I'm at a loss as to why we don't look at 

10 
 protraction effects for the exposure response 

11 for leukemia or vice-versa. 

12 
 Why are we - why would we divide 

13 
 the risk coefficient by DDREF that has an X 

14 
 percent probability of being as large as four 

15 
 saying that there's a real nonlinearity below 

16 
 something as large as 200 millisieverts - and 

17 
 are either of those consistent with a 

18 
 reasonable model for the observed data? 

19 
 DR. KOCHER: Well, that was kind of 

20 
 the BEIR VII's conclusion that they just can't 

21 
 - you just can't find much curvature in that 

22 dose response. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

175 

1 
 So they came up with a small DDREF 

2 
 with low uncertainty bounds. 

3 
 CHAIRMAN RICHARDSON: Yes. 

4 
 DR. KOCHER: But that's a different 

5 
 data set than what Ethel Gilbert would have 

6 
 based her judgments on. 

7 
 CHAIRMAN RICHARDSON: So I kind of 

8 
 fall back on Occam's razor here of saying 

9 
 we're positing factors to describe departures 

10 
 from a simple model and that I find hard to be 

11 consistent with the empirical data. 

12 
 DR. KOCHER: They're not in the data 

13 
 at high doses, but you don't know, you know, 

14 the uncertainties are so big at the -

15 
 CHAIRMAN RICHARDSON: Below 200 

16 
 millisieverts, it's possible in the LSS data 

17 
 for solid cancers to describe - it's 

18 
 consistent with a DDREF of five? 

19 
 That's not my recollection of those 

20 data. 

21 
 DR. TRABALKA: The problem is that 

22 
 the risk coefficients are based on doses from 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

176 

1 
 zero to four gray. 

2 
 CHAIRMAN RICHARDSON: No, but 

3 
 there's a whole series of papers on restricted 

4 
 analyses. You get like 80 percent of the LSS 

5 
 cohorts below 200 millisieverts, I think. 

6 
 DR. TRABALKA: But a DDREF has to 

7 
 account for differences in risk at high doses 

8 
 above 0.5 gray to 4 gray, and doses below 0.5 

9 
 gray. 

10 
 CHAIRMAN RICHARDSON: But the simple 

11 
 model for solid cancers fits the line across 

12 
 the entire range of observed data. 

13 
 DR. TRABALKA: Right. 

14 
 CHAIRMAN RICHARDSON: A reduced 

15 
 model fits the slope over, let's say, a range 

16 
 of zero to 200 millisieverts. And we're 

17 
 saying there is X percent probability that the 

18 
 slope over that restricted range is five-fold 

19 
 lower than it is over the full range. 

20 
 My question is is that at all 

21 
 compatible with the observed data for the 

22 
 lifespan study? 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

 

177 

1 
 DR. TRABALKA: It is. 

2 
 CHAIRMAN RICHARDSON: My 

3 
 recollection is that that -

4 
 DR. TRABALKA: It is for skin 

5 
 cancer. 

6 
 CHAIRMAN RICHARDSON: Yes, but -

7 
 DR. TRABALKA: Look at the figure 

8 
 for skin cancer. 

9 
 CHAIRMAN RICHARDSON: -- this is not 

10 a model primarily for skin cancer, is it? 

11 
 I'm talking about, I mean, I would 

12 
 use if I was going to make a judgment, I would 

13 look at solid cancers as a group. 

14 
 DR. HOFFMAN: I think your question 

15 
 is a good one. And it's certainly something 

16 
 as we move forward into this next phase of 

17 
 peer review and revising our report we need to 

18 
 keep in mind. Because one avenue of attack is 

19 
 to look at various values in our distribution 

20 
 and say are these values even plausible given 

21 the epidemiological data at low doses. 

22 
 And if the answer is, is that 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

178 

1 
 they're not plausible, well, then that speaks 

2 
 towards a revision of our proposed 

3 
 distribution. 

4 
 DR. KOCHER: I think BEIR VII kind 

5 
 of faced the same dilemma. And they ended up, 

6 
 if I remember it correctly, they ended up 

7 
 inflating their uncertainty to account for 

8 
 animal studies. And you may be able to argue 

9 
 that their bounds of uncertainty don't fit the 

10 LSS data. 

11 
 DR. TRABALKA: Just the opposite, 

12 
 David. They used animal data to reduce the 

13 
 uncertainty in the DDREF. The epidemiologists 

14 
 then inflated it back so that the uncertainty 

15 
 represented that and the A-bomb survivor data. 

16 
 Because they said it was just - the 

17 exercise was just too uncertain. 

18 
 DR. HOFFMAN: And to find all that 

19 
 out, you need to read the fine print in the 

20 report. It's not easy to find. 

21 
 DR. TRABALKA: I'd like to make two 

22 final points, and then I'm going to shut up. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

179 

1 
 I like your idea of looking at 

2 
 parametric models. I think the whole exercise 

3 
 of looking at alternate models of the dose 

4 
 response is a very good one. It's something 

5 
 that really hasn't been done up till now and 

6 
 needs to be done. 

7 
 It's being done in conjunction with 

8 
 the development of the German IREP, for 

9 
 example. 

10 And the other is that even though 

11 
 we have a bias, let's say, to certain values 

12 
 of DDREF, if our data sets contain uncertainty 

13 
 such that we have a range, let's say, from 0.5 

14 
 to 5 and we have information that suggests we 

15 
 can have values less than 1, and we have other 

16 
 information that suggests we can have values 

17 
 as high as 5, in fact we have some data that 

18 
 suggests, for example, mortality from lung 

19 
 cancer in tuberculosis fluoroscopy patients 

20 
 that would suggest a threshold even though we 

21 
 all have questions about the meaning of that 

22 data. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

180 

1 
 The UNSCEAR used a quadratic model 

2 
 to fit the data for bone cancer in the A-bomb 

3 
 survivors. That's a very different one. It 

4 
 produces a risk at low doses that's very high. 

5 
 It produces a DDREF that's very great. 

6 
 And your point about, yes, if we 

7 
 lump all the solid cancers together and we get 

8 
 what looks like this interesting straight 

9 
 line, is that model representative of the data 

10 all over the entire four-sievert range. 

11 
 If we fit a model that had to 

12 
 accept all of the data from zero to four 

13 
 sieverts, would it have the same linearity as 

14 
 the data from zero to one and a half sieverts 

15 
 or two sieverts that's currently being 

16 modeled? 

17 
 No, because you'd have to have a 

18 
 cell-killing component that would affect the 

19 
 curvature at the low end and the low doses. 

20 It's going to change it. 

21 
 The A-bomb survivor data had not 

22 
 been adjusted for effects of smoking. What 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

181 

1 
 would happen if we took out lung cancers and 

2 
 related cancers? 

3 
 The data for the A-bomb survivors 

4 
 for digestive cancers are clearly different in 

5 
 terms of the incidence of those cancers from 

6 
 Western populations and other populations. 

7 
 What would happen if we took those 

8 
 out and then remodeled the data? Are we going 

9 
 to get such a perfect straight line? 

10 
 These kinds of uncertainties are 

11 
 still inherent in the A-bomb survivor data. 

12 
 It's the best data set we have, but it's not 

13 perfect. We have no perfect data sets. 

14 
 That's why I'm saying is we have to 

15 
 be very careful not to restrict uncertainty 

16 
 unnecessarily because of some preconceived 

17 assumptions that we have. I would rather -

18 
 CHAIRMAN RICHARDSON: I'm not 

19 talking about restraining uncertainty. 

20 
 DR. TRABALKA: No, I know you're 

21 
 not. 

22 CHAIRMAN RICHARDSON: There's 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

182 

1 
 actually been quite a bit done on assessment 

2 
 of confounding by smoking. 

3 
 DR. TRABALKA: That's not -

4 
 CHAIRMAN RICHARDSON: I'm saying if 

5 
 there's uncertainty in the risk coefficient 

6 
 and there's already been uncertainty factors 

7 
 added into the risk coefficients to deal with 

8 
 transporting risk coefficients from a Japanese 

9 
 population with different baseline rates to 

10 
 another one, there's uncertainty coefficients 

11 
 added in for dealing with potential 

12 
 confounders, but there's - if you want to add 

13 
 in more uncertainty, then just increase the 

14 uncertainty. 

15 
 The kind of - if that's what this 

16 
 is about, then just make it much simpler. 

17 
 Just take the risk coefficient and increase 

18 the uncertainty at the low-dose range. 

19 
 DR. HOFFMAN: And, in fact, that's 

20 exactly what's being done at this point. 

21 
 CHAIRMAN RICHARDSON: Okay, maybe 

22 that's it. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

183 

1 
 DR. HOFFMAN: I mean, it's not that 

2 
 there's something magical in this DDREF. The 

3 
 fact that the central value is moving closer 

4 
 towards one, but then as the dose goes down, 

5 
 we increase the uncertainty, but the overall 

6 
 functional effect is exactly as you say. 

7 
 CHAIRMAN RICHARDSON: Okay, that's 

8 
 great then. What I would suggest is we can 

9 
 say, you know, previously what was done was we 

10 
 divided the risk coefficient by a value that 

11 
 was not unity and we had an uncertainty 

12 
 distribution about it, which had lots of 

13 implications. 

14 
 What we're suggesting is 

15 
 extrapolation down to low doses implies 

16 
 uncertainty. So we're going to increase the 

17 uncertainty on the risk estimates. 

18 DR. HOFFMAN: Yes. 

19 
 CHAIRMAN RICHARDSON: That's a very 

20 
 straightforward story. I found that 400 pages 

21 
 of arguments about kind of biological 

22 processes really was obscuring something. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

184 

1 
 What you're talking about is 

2 
 uncertainty due to statistical and precision 

3 
 in risk assessments as you extrapolate the low 

4 
 doses. 

5 
 That's a one-paragraph -

6 
 MEMBER ZIEMER: But I don't think 

7 
 they're describing it that way. Maybe the -

8 
 DR. NETON: The distribution is 

9 
 closer to one, but it's not one in the central 

10 estimate. 

11 
 CHAIRMAN RICHARDSON: It's not, 

12 
 exactly. So we've introduced something more 

13 
 complicated. And I'm asking, you know, I'm 

14 
 still not satisfied with the description of 

15 the etiology of the complication. 

16 
 DR. TRABALKA: Well, if you have 

17 
 suggestions for alternate choices of data and 

18 approach, we certainly welcome them. 

19 
 DR. KOCHER: Yes, I have some 

20 
 misgivings about saying that the dose response 

21 
 for all solid cancers combined defines DDREF 

22 because that -

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

185 

1 
 CHAIRMAN RICHARDSON: Well, I do 

2 
 too. 

3 
 DR. KOCHER: That implies that every 

4 
 - IREP is interested in individual cancers. 

5 
 And you kind of have to bear that in mind. 

6 
 DR. TRABALKA: You know, and there's 

7 
 a page that has a set of figures from 

8 
 Preston's report, the dose responses for the 

9 
 individual cancers, and there's also another 

10 
 one that - another page that shows the dose 

11 
 response for skin cancer and those data are 

12 all over the map. 

13 
 CHAIRMAN RICHARDSON: You're talking 

14 
 about the estimate of the magnitude and shape 

15 
 of the site-specific cancer risk; is that 

16 right? 

17 DR. TRABALKA: Let's look at -

18 
 CHAIRMAN RICHARDSON: Yes, and again 

19 
 I would say as you get to site-specific cancer 

20 
 risk coefficients, they have larger 

21 
 uncertainties than the analyses in which you 

22 
 pool categories of either cause of death or 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

186 

1 
 types of cancers. 

2 
 DR. TRABALKA: That's right. 

3 
 CHAIRMAN RICHARDSON: I mean, again, 

4 
 this is by definition. 

5 
 DR. TRABALKA: Right. 

6 
 CHAIRMAN RICHARDSON: Statistical 

7 
 imprecision and uncertainty. 

8 
 DR. TRABALKA: The figures on Page 

9 
 136, for example, from Preston and Company's 

10 
 report, if you compare the parametric -

11 
 nonparametric fit, for example, with the 

12 
 linear extrapolation, you get to see some 

13 
 rather interesting variations that are, in 

14 
 part, statistical in nature and give you some 

15 idea of what the uncertainty might be. 

16 
 Looking at the one, the figure for 

17 
 thyroid cancer on Page 136, Preston and 

18 
 Company made the observation that doses below 

19 
 about half a gray or roughly in that region, 

20 
 that there appeared to be a pattern of perhaps 

21 super linearity in the response. 

22 
 So and you look at lung cancer, you 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

187 

1 
 can see something similar to that. So there 

2 
 are all kinds of ways you can interpret the 

3 
 low-dose response in these data. 

4 
 But I think looking at alternative 

5 
 models like you suggested is an interesting 

6 
 exercise that should be done. 

7 
 DR. HOFFMAN: And, in fact, in other 

8 
 work that we're involved with, with Dale 

9 
 Preston, Charles Land and Peter Jacob and his 

10 
 colleagues in Germany, they are developing 

11 
 approaches whereby the uncertainty on site12 
 specific cancer risks will include modeling 

13 
 uncertainty accounting for multiple models 

14 that plausibly fit the data. 

15 
 This is something that up until 

16 
 now, no international group has undertaken to 

17 
 include the effect of model uncertainty above 

18 
 and beyond the selection of one model and 

19 
 including simply statistical uncertainty on 

20 the fit to the epidemiological data. 

21 
 CHAIRMAN RICHARDSON: I certainly 

22 
 agree that as you move to risk coefficients 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

188 

1 
 for site-specific diseases, there's greater 

2 
 uncertainty in the risk estimations and there 

3 
 is greater sensitivity to model selection. 

4 
 I mean, that, you know, again 

5 
 you'll end up with a model best estimate and 

6 
 an estimate of the variance of the risk 

7 
 coefficient. 

8 
 So I think that the suggestion that 

9 
 we provide a brief report maybe talking about 

10 
 the awareness of new data, SENES' efforts to 

11 
 evaluate that and report to NIOSH, and I mean, 

12 
 I agree this is a really important and not 

13 straightforward issue. 

14 
 I would hope that the - as we move 

15 
 forward, I mean, maybe, I mean, NIOSH seems 

16 
 like they're going to have an important role 

17 
 in moving this report out to kind of a broader 

18 
 discussion in the scientific community about 

19 DDREF. 

20 
 And as they do that, I mean, maybe 

21 
 we could have some comments about the utility 

22 
 of kind of clarifying and hopefully 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

189 

1 
 streamlining what has the appearance of being 

2 
 in many cases, a very subjective kind of 

3 
 approach to handling this form of uncertainty. 

4 
 I think that there's probably more 

5 
 that can be done. I mean, what do other 

6 
 people in the Work Group think? Would you 

7 
 like, I mean, as a first step, that we follow 

8 
 something along a brief report to the Board 

9 
 along the lines that Dr. Ziemer suggested? 

10 
 MEMBER ZIEMER: Well, of course I 

11 
 like my own idea, but I would amend it a 

12 
 little bit. Some of the concerns that you 

13 
 raised, I think we can raise those as well 

14 that we hope that these issues are looked at. 

15 
 It's always appeared to me that to 

16 
 some extent we get driven into fiddling with 

17 
 these models because they have gotten accepted 

18 
 like the BEIR VII. And you end up with, okay, 

19 
 this is the accepted model. So, now how do we 

20 adjust this so it fits what we're doing here? 

21 
 If we go back to the logical 

22 
 simplest case, which is just a linear model, 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

190 

1 
 which from a physics point of view is what you 

2 
 can strive for, the simplest model is what 

3 
 you'd like, and then everything else 

4 
 particularly at the low end is uncertainty, 

5 
 even if it makes sense, it's going to be 

6 
 harder to sell simply because of the way these 

7 
 things have developed over years. 

8 
 And, in part, because of attacks on 

9 
 the linear model, which I suppose reflect some 

10 
 different worlds. One is the epid world, 

11 
 which is -- it certainly makes sense. And the 

12 
 other is the health physics world where we 

13 
 have, to some extent, run into problems with 

14 
 going as low as reasonably achievable and then 

15 
 saying, yes, but there's still risks there and 

16 
 arguments about the risk being greater at the 

17 
 low doses and all of those kinds of things 

18 
 we've gone through those gyrations over 

19 
 decades now. And we find ourselves in this 

20 
 kind of dilemma as to what does it look like, 

21 
 what's the model. 

22 
 So to some extent we end up - and 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

191 

1 
 I'm not arguing that we shouldn't do this, but 

2 
 you sort of end up fighting the scientific 

3 
 establishment for how you model dose. 

4 
 But I think it's worth raising the 

5 
 issues and maybe SENES goes back and can think 

6 
 about some alternatives to - well, you can 

7 
 accomplish the same thing by this in this 

8 
 simple way. That may be worth looking at too. 

9 
 I don't know. 

10 
 But I think David's raised some 

11 interesting points for us to think about. 

12 
 MR. KATZ: Just from a process 

13 
 standpoint, I'm just also wondering, I think 

14 
 raising these questions might be very useful 

15 for the peer review context as well. 

16 I mean, why not put those -

17 
 MEMBER ZIEMER: Yes, you can ask the 

18 
 reviewers to think in terms of as those 

19 
 questions even if you - even if they are not 

20 
 explicitly raised, maybe could you accomplish 

21 
 this just as easily in this other manner. I 

22 don't know. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

192 

1 
 DR. HOFFMAN: Well, I think we're 

2 
 going to take these seriously one way or 

3 
 another. And as we work through this report, 

4 
 I mean, if it turns out that for acute 

5 
 exposures there is a more transparent 

6 
 straightforward way of handling the increase 

7 
 in uncertainty in risk with decreasing dose, I 

8 
 would like to recommend that that be adopted. 

9 
 But right now, this is the best 

10 we've been able to do. 

11 MEMBER MUNN: From my perspective -

12 
 MEMBER FIELD: This is Bill. Can I 

13 just make a comment or two? 

14 MEMBER MUNN: Please. 

15 
 MEMBER FIELD: Yes, I've just been 

16 
 listening to this and I'll tell you my 

17 learning curve has been at a high rate here. 

18 MEMBER MUNN: Is it bent? 

19 
 MEMBER FIELD: I think I have 

20 
 previous knowledge about some of the aspects 

21 
 of the report. But, boy, the scope of the 

22 
 knowledge you need to understand the report in 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

193 

1 
 its totality with all the possible 

2 
 interactions with the topical areas has been a 

3 
 bit challenging for me. 

4 
 And this whole process I think 

5 
 would be a lot easier, obviously, if there was 

6 
 somebody else that had some sort of report 

7 
 that was considered a consensus. 

8 
 I think what we're running into is 

9 
 that the report as presented is very pushing 

10 
 the envelope as far as what's known. And we 

11 
 don't really know what the consensus will be 

12 
 on this report from content experts or the 

13 public or others. 

14 
 So I think at this point, I think 

15 
 content experts, to me it's very critical to 

16 
 really see where the points of agreement lie 

17 
 or where the points of disagreement lie that 

18 we can explore further. 

19 
 And I think considering that, it's 

20 
 going to be very important to figure out which 

21 
 five people you ask to review it. Because as 

22 
 you know, you can pick five people that you 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

194 

1 
 know a priori will probably consent on it or 

2 
 probably say, this is pretty good stuff. 

3 
 So I think getting a diverse group 

4 
 of reviewers would be good. And I would favor 

5 
 five as opposed to three. And I think once 

6 
 that process is done, then I think it would be 

7 
 interesting then to come back together and see 

8 
 if they found some of the similar problems 

9 
 that Dave has brought up or some of the 

10 
 similar concerns, to see if they also are 

11 sharing those concerns. 

12 
 MEMBER MUNN: Thank you, Bill. This 

13 
 is Wanda, and this - Bill's comments bring me 

14 
 back, I think, to my original question which 

15 
 may need to be deferred until after we've had 

16 
 our discussion that we mentioned earlier at 

17 our next meeting. 

18 
 And that is, is the purpose of this 

19 
 group to help define the science, or is the 

20 
 purpose of this group to report out that we 

21 
 feel that the agency is or is not pursuing the 

22 
 proper effort to assure that the best science 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

195 

1 
 is being used? 

2 
 It's a fairly basic question, I 

3 
 think, and one with which I think the Work 

4 
 Group needs to come to grips very clearly 

5 
 because there's an enormous difference in 

6 
 whether or not we will immerse ourselves in 

7 
 the science of this process as it goes 

8 
 forward, or whether we will make a judgment 

9 
 call as to whether or not the agency is 

10 
 pursuing the best science. Two entirely 

11 different questions. 

12 
 MR. KATZ: Can I say something to 

13 this? 

14 I mean, I think -

15 MEMBER MUNN: Can I stop you? 

16 
 MR. KATZ: You can if you want to, 

17 
 but I think the Board can do both in a sense. 

18 
 I mean, I think the Board is welcome 

19 
 particularly when the agency invites it, to 

20 
 provide counsel along the way, as well as at 

21 
 the end of the day provide advice, counsel on 

22 
 what it thinks about the results that the 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

196 

1 
 agency thinks it's going to take. 

2 
 So, I don't think there's really 

3 
 necessarily an either/or here. And the agency 

4 
 is clearly asking for advice along the way. 

5 
 And I think as deep as you are able to go on 

6 
 that question is being welcomed. 

7 
 So it's really more a matter of 

8 
 your capacity to provide such advice, but I 

9 
 don't think you're constrained. That's my 

10 point of view. 

11 
 MEMBER MUNN: Well, it's a point I 

12 
 think we need to come to some agreement on as 

13 a Work Group. 

14 
 CHAIRMAN RICHARDSON: Again, we did 

15 
 have a discussion about scope and process. 

16 
 And I think what I'll do is recirculate the 

17 
 discussion of the scope and the points that 

18 
 were laid out there, and then we can talk 

19 about that again. 

20 
 I would view the scope as something 

21 
 larger than saying is the process NIOSH is 

22 
 taking sufficient. I hope that we can talk 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

197 

1 
 about the substance of the issues as well. 

2 
 That's, I mean, the way that we talk about the 

3 
 substance of other technical issues, which is 

4 
 to provide some form of evaluation and comment 

5 
 on them. 

6 
 MEMBER MUNN: Well, it would be hard 

7 
 for us to take a position as to whether or not 

8 
 the process is appropriate without spending 

9 
 some time looking at the nitty-gritty. 

10 
 There's no question about that. We have to 

11 
 know what is going on and what the issues are 

12 
 if we're going to weigh in on whether or not 

13 it's appropriate. 

14 CHAIRMAN RICHARDSON: Yes. 

15 
 MEMBER ZIEMER: And I don't think we 

16 
 will, as a Work Group, come up with sort of 

17 
 the decision on whether a linear low-threshold 

18 
 model is the preferred one over - but we want 

19 
 to make sure the questions are asked and that 

20 
 the scope of what's being done is being fully 

21 
 considered in going - I mean, I'm going to 

22 
 rely on the experts because that, you know, we 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

198 

1 
 work, you know, some of us even teach about 

2 
 there being a no-threshold model, but we're 

3 
 not, you know, the experts on the biology or 

4 
 even the statistics of it. 

5 
 MEMBER ROESSLER: That's one whole 

6 
 lecture on the various models. 

7 
 MEMBER ZIEMER: Oh, I can stretch it 

8 
 into two if necessary. 

9 
 (Laughter.) 

10 
 CHAIRMAN RICHARDSON: I think 

11 
 there's - I get the sense that there's 

12 
 agreement that there's going to be a lot of 

13 
 value in seeing what Bill was calling the 

14 
 content experts, seeing what they come back 

15 with. And I think that makes a lot of sense. 

16 
 I think it would be worthwhile for 

17 
 us to maybe at the next meeting at least 

18 
 whether it's in written form or orally, at 

19 
 least, to update the Board on what we're 

20 doing. 

21 Does that make sense? 

22 MEMBER MUNN: Yes. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

199 

1 
 CHAIRMAN RICHARDSON: And then to 

2 
 kind of move forward with kind of keeping an 

3 
 eye on the process that NIOSH is going to take 

4 
 with their external review and hopefully have 

5 
 an opportunity to read over the comments that 

6 
 come back from the content experts. And 

7 
 expect that we'll take it upon ourselves to at 

8 
 that point, provide a follow-up discussion 

9 
 maybe in a little bit more formal sense based 

10 on their comments in the report. 

11 
 MEMBER ROESSLER: David, with regard 

12 
 to the selection of the content experts, and I 

13 
 think we're wanting to do it fairly soon, do 

14 
 you see that the Work Group would ask to be 

15 
 involved in the decision on that at some 

16 point, some soon date? 

17 
 CHAIRMAN RICHARDSON: I don't know. 

18 
 I think NIOSH usually has a fairly formal 

19 process laid out for that, don't they? 

20 
 MEMBER ROESSLER: NIOSH just went 

21 out for a minute. 

22 
 MR. KATZ: Jim Neton stepped out. I 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

200 

1 
 mean, they have a process for selection, but, 

2 
 I mean, I think they are open to suggestions. 

3 
 I mean, I think they start with a pool and a 

4 
 number of factors as to what they end up with, 

5 
 including willingness to perform. 

6 
 So, I would just say to all of you 

7 
 here, I mean, on the Work Group that certainly 

8 
 if you have people in mind that you think 

9 
 should be considered, NIOSH will be glad to 

10 hear that. 

11 
 MEMBER ZIEMER: Yes, I wouldn't want 

12 us to review names -

13 MR. KATZ: I'm not saying -

14 
 MEMBER ZIEMER: -- as a Work Group, 

15 but individually -

16 
 MR. KATZ: Yes, that's what I mean. 

17 
 And it's NIOSH's decision, but certainly any 

18 
 advice, suggestions you have I think will be 

19 helpful to NIOSH in this next step. 

20 
 MEMBER MUNN: We could always ask 

21 NIOSH about it after lunch. 

22 
 MR. KATZ: NIOSH being Jim Neton who 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

 

201 

1 
 stepped out, you mean, right? 

2 
 MEMBER MUNN: Lunch being -

3 
 MR. KATZ: I don't think he'll tell 

4 
 you anything much different. 

5 
 MEMBER MUNN: Lunch being the 

6 
 operative word. 

7 
 MR. KATZ: I understand that lunch 

8 
 is on your mind. 

9 
 MEMBER ZIEMER: David, do you plan 

10 
 to give sort of an interim report at our 

11 
 teleconference? At least report on this 

12 meeting. It's coming up in two weeks. 

13 
 CHAIRMAN RICHARDSON: That sounds 

14 like a good idea. 

15 
 MEMBER ROESSLER: What date is the 

16 
 teleconference? 

17 MR. KATZ: April 26th at 11:00 a.m. 

18 MEMBER MUNN: Correct. 

19 
 MR. KATZ: The question was, when 

20 
 was the Board teleconference, for those folks 

21 on the phone who -

22 MEMBER ZIEMER: April 26th. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

202 

1 
 MR. KATZ: Right. So do we have a -

2 
 Wanda is almost making the motion for lunch. 

3 
 MEMBER MUNN: Yes, I am. 

4 
 MR. KATZ: But let me just ask, 

5 
 because it's not clear to me, do we have an 

6 
 agenda for after lunch? 

7 
 MEMBER MUNN: Guess I thought we 

8 
 did. Don't we have several other items? 

9 
 CHAIRMAN RICHARDSON: My sense is 

10 
 that on this topic, we're at a stopping point 

11 
 with DDREF unless there are clear ways forward 

12 
 aside from providing kind of a report on our 

13 
 status and the status of NIOSH's activities 

14 
 and then holding this topic until we see back 

15 kind of the external review. 

16 
 MR. KATZ: So then the only question 

17 
 that I think I'd raise in an email - hope I 

18 
 didn't - maybe I didn't - was whether the Work 

19 
 Group wants to at this point, and you may not, 

20 
 to discuss the rest of the agenda other than 

21 
 this of this Work Group, whether you want to -

22 
 whether you need any discussion of what other 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

203 

1 
 items are on that agenda and their path 

2 
 forward, etc. 

3 
 MEMBER ZIEMER: Well, what were 

4 
 these other slides that were in our packet 

5 
 that you sent out? Were those from NIOSH path 

6 
 forward? 

7 
 DR. NETON: You mean the - there was 

8 
 an agenda that was sent out. 

9 
 MEMBER ZIEMER: No, there were two 

10 sets of slides you sent us. 

11 
 DR. HOFFMAN: That other thing, get 

12 
 rid of it because that's supposed to be an 

13 internal discussion between us and NIOSH. 

14 (Simultaneous speaking.) 

15 
 MR. KATZ: So everyone in the Work 

16 
 Group, just to be clear, what I sent forward 

17 
 this morning to the Work Group was what I 

18 received from SENES. 

19 
 MEMBER MUNN: Can someone please 

20 tell me what SENES stands for? Nobody knows? 

21 
 DR. HOFFMAN: Yes, to give you the 

22 story -

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

 

204 

1 
 DR. KOCHER: Just give them the 

2 
 answer. It's lunchtime, Owen. Define the 

3 
 acronym. 

4 
 DR. HOFFMAN: Yes, but I have to get 

5 
 warmed up into it. It's Scientists -

6 
 DR. KOCHER: No, it's not. 

7 
 DR. HOFFMAN: Specialist - okay, you 

8 
 name it. I can't remember. 

9 
 DR. KOCHER: Well, it's the 

10 
 specialist part. And then N is nuclear and S 

11 
 is sciences. And then the two Es are either 

12 energy and environmental or vice-versa. 

13 
 DR. APOSTOAEI: No, it stands for 

14 
 Specialists in Energy, Nuclear and 

15 Environmental Sciences. 

16 MEMBER MUNN: All right. 

17 
 DR. HOFFMAN: We get asked that 

18 question so seldom. 

19 
 DR. KOCHER: The N stands for 

20 
 nuclear. And the two Es stand for 

21 environmental and energy. 

22 (Simultaneous speaking.) 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

205 

1 
 DR. APOSTOAEI: Specialists in 

2 
 Energy, Nuclear and Environmental Sciences. 

3 
 DR. HOFFMAN: Specialists in Energy, 

4 
 Nuclear and Environmental Sciences. 

5 
 MEMBER MUNN: Thank you. 

6 
 DR. HOFFMAN: It goes way back to 

7 
 the Canadian firm in Toronto that wanted to 

8 
 name their firm Energy Nuclear and 

9 
 Environment, and someone else had ENE already 

10 
 coined. So, they put Ss on either side of it. 

11 
 And then later people said, what 

12 
 does SENES stand for? What does SENES stand 

13 
 for? Specialists in Energy, Nuclear and 

14 Environmental Studies. 

15 
 MR. KATZ: So let me just return to 

16 
 the question so that we can decide whether 

17 we're adjourning or we're breaking for lunch. 

18 
 David and the Work Group, do you 

19 
 have any discussion, do you want any 

20 
 discussion at this point about other agenda 

21 items of the Work Group? 

22 
 CHAIRMAN RICHARDSON: Well, I think 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

206 

1 
 at the next Work Group meeting we would return 

2 
 to the topic of scope and process. And then 

3 
 one of the suggestions as another topic was 

4 
 something that's going to parallel this very 

5 
 closely was issues of RBE. And I believe 

6 
 SENES has a report as well on that, which if 

7 
 it's available, we may want to ask for that 

8 
 and kind of follow a similar line. 

9 
 Is Jim back? 

10 DR. NETON: Yes, I'm back. Sorry. 

11 
 CHAIRMAN RICHARDSON: Does that -

12 would that be possible, and is that -

13 
 DR. NETON: Yes, I'm trying to 

14 
 remember if there is actually a standalone 

15 
 report, or is it just the Health Physics 

16 publication? I think there's a NIOSH report. 

17 
 DR. KOCHER: There's a huge paper on 

18 your website that was put up in 2002. 

19 
 DR. NETON: You're right. You're 

20 
 right. So, yes, that's out there available 

21 
 now. 

22 DR. KOCHER: And that represents 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

207 

1 
 what's in the program, what's in the code. 

2 
 There's nothing like this DDREF report about 

3 
 what might come next. 

4 
 DR. NETON: No, no. There's not 

5 
 been any additional work on our radiation 

6 
 effectiveness factors. The report that's out 

7 
 there is what we're using - intend to use, but 

8 
 it could be summarized on a presentation. 

9 
 Because as we pointed out or discussed, some 

10 
 of the high-LET distributions are affected by 

11 DDREF applications. 

12 
 MEMBER ZIEMER: We did have a list 

13 
 that we prioritized at our previous meeting of 

14 
 the issues that we'd look at. I don't recall 

15 the top five, but -

16 
 CHAIRMAN RICHARDSON: I believe RBE 

17 
 was number two. 

18 MEMBER ZIEMER: Okay. 

19 
 CHAIRMAN RICHARDSON: There was also 

20 
 issue - the third one on that list if I'm 

21 
 recalling correctly, it was the adjustment of 

22 
 Probability of Causation based on other 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

208 

1 
 factors. 

2 
 There was interest in reviewing 

3 
 smoking and radiation joint effects. 

4 
 MEMBER MUNN: Yes, there was that. 

5 
 CHAIRMAN RICHARDSON: And both of 

6 
 those would be, you know, again, meaty topics 

7 
 to get into and report back on. 

8 
 MEMBER ZIEMER: Well on RBE, is 

9 
 there anything active going on in the agency 

10 
 there? And I guess my question is are there 

11 
 particular issues that we would need to 

12 
 address on RBE versus smoking, which I know we 

13 
 adjust for smoking in part of the model for 

14 
 lung cancers, but is there additional smoking 

15 
 information that's available that should be 

16 looked at? Anything new there? 

17 
 CHAIRMAN RICHARDSON: There were 

18 
 some questions about how joint effects were 

19 
 being handled. And this has come up several 

20 
 times, I think, at the full Board meetings. 

21 
 And some interest in asking that there be some 

22 
 evaluation of kind of time friendliness of 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

209 

1 
 those -

2 
 DR. NETON: Yes, I think Dr. Lemen 

3 
 raised an issue some time ago. 

4 
 MR. KATZ: Yes, I think that's 

5 
 right. 

6 
 DR. NETON: That sort of was the 

7 
 genesis, I think, of the Science Work Group 

8 
 being put together, was a question that was 

9 
 raised on smoking and interaction, I believe. 

10 CHAIRMAN RICHARDSON: Right. 

11 MEMBER MUNN: Yes. 

12 
 DR. NETON: Susan Reutman, our 

13 
 epidemiologist, is working on that issue now 

14 
 doing some pretty extensive annotated --

15 
 searches and stuff to build up an annotated 

16 bibliography of -

17 
 MEMBER ZIEMER: Well, would it be of 

18 
 value just to have sort of an update on what -

19 
 DR. NETON: We could describe what 

20 
 we currently do and how it evolved and what's 

21 maybe out there. 

22 
 MEMBER ZIEMER: And what's out 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

210 

1 
 there, what the issues are. And we obviously 

2 
 aren't in a place where we would do anything 

3 
 to -

4 
 DR. NETON: Correct. Because, you 

5 
 know, we've always maintained as the science 

6 
 evolved, we may revisit that issue. 

7 
 CHAIRMAN RICHARDSON: Yes, there 

8 
 was, you know, RERF had a report either in 

9 
 2011 or very early 2012 on fitting some new 

10 
 joint models for smoking and radiation with 

11 
 lung cancer, which went a good ways beyond 

12 
 what had been done previously with those data. 

13 
 So that would be useful to kind of also 

14 consider. 

15 
 MEMBER MUNN: But also based on the 

16 
 notes from your last meeting before you go 

17 
 away from the idea of the RBE issues, even 

18 
 though that does not seem to be a burning 

19 
 issue or one that's of as much interest as the 

20 
 smoking and PoC questions, since SENES has 

21 
 done a recent update of where we are with 

22 
 that, it would seem only logical that we would 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

211 

1 
 want to at least hear about that. 

2 
 And as you suggested last time, 

3 
 David, report back to the Board on the status 

4 
 of the assumptions that are made in RBEs, our 

5 
 assertion that they are or are not good 

6 
 science. 

7 
 DR. NETON: Well, I'm a little 

8 
 confused, Wanda. There is no update by SENES 

9 
 on the radiation effectiveness factor. 

10 MEMBER MUNN: Oh. 

11 
 DR. NETON: It stands as it was, and 

12 we currently have no plans to revisit that. 

13 MEMBER MUNN: Okay. 

14 
 DR. TRABALKA: Wanda may have been 

15 
 referring to what I said that David's involved 

16 in an NCRP committee that's looking at those. 

17 
 MEMBER MUNN: No, I was just reading 

18 
 from that from the transcript from last time. 

19 
 Led me to believe that a study that SENES has 

20 
 recently done is an update of all the 

21 information on the RBEs. 

22 That's all right. Forget it. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

212 

1 
 CHAIRMAN RICHARDSON: And switching 

2 
 the order so that we deal with the PoC and 

3 
 then maybe come back to the RBE might also be 

4 
 useful because the NCRP is looking at this 

5 
 issue. They may be further along. Maybe they 

6 
 won't be. 

7 
 MR. KATZ: So just to remind you all 

8 
 as well because these - seems like these are 

9 
 all IREP-related matters, but there are some -

10 
 - these would have been termed differently, 

11 
 cross-cutting or whatever, science issues 

12 
 related to dose reconstruction that also have 

13 
 been suggested might be considered by this 

14 
 Work Group. They were in the lineup, I think, 

15 as I understand it. 

16 
 DR. NETON: I thought the decision 

17 
 was made early on not to include those because 

18 
 they're handled under a different format like 

19 
 the Procedures Work Group handles those cross20 cutting issues. 

21 
 MEMBER ZIEMER: You mean like the 

22 resuspension factor? 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

213 

1 
 DR. NETON: Resuspension factors and 

2 
 that sort of thing, yes. 

3 
 MR. KATZ: There have been a 

4 
 variety. And I've shared - I've sent, I 

5 
 think, to the whole Work Group, as well as to 

6 
 David, emails including some transcript 

7 
 material that was suggested by the Procedures. 

8 
 But the Procedures Subcommittee had sort of 

9 
 expressed -

10 DR. NETON: But I think if you go 

11 
 back and read, I think that was all sent out. 

12 
 And I think at some point when the Work Group 

13 
 developed their charter or mission statement, 

14 
 I thought that they agreed to focus primarily 

15 on risk model issues. I could be wrong. 

16 
 MR. KATZ: No, that was never 

17 explicitly discussed, I don't think. 

18 DR. NETON: Really? 

19 
 MR. KATZ: If it was, I missed that. 

20 
 DR. NETON: Well, David's the chair. 

21 
 He can -

22 MR. KATZ: David, what's -

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

214 

1 
 CHAIRMAN RICHARDSON: That was early 

2 
 on kind of in the discussion of scope, 

3 
 science-based issues impacting on risk models 

4 
 used by the program and that the group would 

5 
 focus on risk model issues. 

6 
 So are there - Ted, you're pushing 

7 
 for scope creep? 

8 
 MR. KATZ: I'm not pushing at all. 

9 
 So let me make that clear. But there were a 

10 
 number of items that were more dose 

11 
 reconstruction, but sort of fundamental - or 

12 
 cross-cutting dose reconstruction matters, 

13 
 more science than sort of particulars related 

14 
 to sites or what have you, things that have 

15 
 arisen that a number of sites and caused 

16 
 concern and never been really properly put to 

17 bed. 

18 
 And there certainly were at least 

19 
 suggestions on the Procedures Subcommittee 

20 
 that these might be matters best taken up by 

21 
 the Science Issues Work Group versus the 

22 Procedures Work Group. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

215 

1 
 So that's the discussion that 

2 
 arose. And some of these items were, I think, 

3 
 in the list that sort of was the -

4 
 DR. NETON: Well, there were two I 

5 
 think. 

6 
 MR. KATZ: Anyway, of this Work 

7 
 Group produced by Jim Neton. So those weren't 

8 
 - those items weren't prioritized when the 

9 
 Work Group first met, the Science Issues Work 

10 
 Group first met, but they were raised in an 

11 
 initial paper that I gave to the Issues Work 

12 Group. 

13 
 And then since then, I have, like I 

14 
 said, I think shared some transcripts and 

15 
 other materials with you, David, when the 

16 
 question arose in the Procedures Subcommittee. 

17 
 So it's clear that no one is ready 

18 
 to take that up right now, that issue. But I 

19 
 think maybe at the next meeting you might want 

20 
 to just consider those issues and whether they 

21 
 deserve to be addressed by this group or rest 

22 with other groups. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

216 

1 
 Procedures is the only sort of 

2 
 generic group there is to otherwise take them 

3 
 up, but it's constituted very differently than 

4 
 this group. I mean, you have a lot of 

5 
 scientists on this group that are good for 

6 
 some of these issues, I think. 

7 
 MEMBER MUNN: We perhaps can shine a 

8 
 little light on that by next time. 

9 
 CHAIRMAN RICHARDSON: That sounds 

10 good. 

11 MR. KATZ: Okay. 

12 
 CHAIRMAN RICHARDSON: Well if - I 

13 know Wanda is hungry. 

14 
 MEMBER MUNN: You bet your bottom 

15 dollar. 

16 
 CHAIRMAN RICHARDSON: So I would 

17 
 suggest adjourning at this point if that's 

18 acceptable. 

19 
 MEMBER MUNN: If we have nothing 

20 more to discuss, then -

21 MEMBER ZIEMER: I move we adjourn. 

22 MEMBER MUNN: Second. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

217 

1 
 MEMBER LEMEN: I'll second it. 

2 
 MR. KATZ: It's good to hear your 

3 
 voice, Dick. 

4 
 MEMBER LEMEN: Well, I'm still here. 

5 
 I've learned a lot today. 

6 
 DR. NETON: Just to clarify, I'm 

7 
 looking at the Science Issues Work Group 

8 
 mission statement on our website. 

9 
 (Simultaneous speaking.) 

10 
 DR. NETON: It says is responsible 

11 
 for reviewing the status and number of risk 

12 
 model issues that have been identified as 

13 
 important for the EEOICPA program. These 

14 
 include incorporation of epidemiologic 

15 
 studies, DDREF, cancer, age-at-exposure. the 

16 
 Work Group will review the status of the 

17 current work and report back to the Board. 

18 
 MR. KATZ: I'm familiar with that, 

19 
 but that was generated after the first meeting 

20 
 where we just came up with this initial 

21 
 priority list and some of the things just 

22 really weren't addressed in that discussion. 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

 

 

 

 

218 

1 
 DR. NETON: All right. I thought it 

2 
 was the other way around. 

3 
 MR. KATZ: No, it wasn't. We 

4 
 actually it took a while to clarify that 

5 
 charge. We started off thinking we knew the 

6 
 charge. And then we readdressed it and came 

7 
 back to the Board. 

8 
 DR. NETON: Okay. 

9 
 MR. KATZ: Anyway, it's -

10 DR. NETON: Okay. 

11 
 MR. KATZ: We can resolve it at the 

12 next meeting. 

13 
 MEMBER ZIEMER: Well, I think the 

14 
 Work Group can look at those overarching 

15 
 issues and see if there are science issues in 

16 
 there that we need to look at. 

17 
 MR. KATZ: Right. I mean, the scope 

18 
 can be changed. So the important issue is 

19 
 where is the best place to address those 

20 
 issues, not whatever scopes are specified 

21 currently for these different Work Groups. 

22 
 Okay. So I think we're -- thank 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 
 

 

 

219 

1 
 you, everyone. David, thank you. 

2 
 CHAIRMAN RICHARDSON: Sure. And I 

3 
 look forward to seeing you soon. 

4 
 MR. KATZ: Yes. Take care. 

5 
 (Whereupon, the meeting was 

6 
 adjourned at 12:52 p.m.) 

7 
 

8 
 

9 
 

10 

11 

12 

13 

14 

15 

16 

17 

NEAL R. GROSS 

COURT REPORTERS AND TRANSCRIBERS 

1323 RHODE ISLAND AVE., N.W. 

(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com