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A- £3-22, TH-^-S 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

SCIENCE ADVISORY BOARD 

CLEAN AIR SCIENTIFIC ADVISORY COMMITTEE 

LEAD EXPOSURE SUBCOMMITTEE 

Open Meeting 

United States Environmental Protection Agency 

Mall Level, Conference Room North 3 

401 M Street, Southwest 

Washington, D. C. 20460 

Tuesday, October 25, 1988 

9:30 a.m. 

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APPEARANCES 

DR. TIMOTHY LARSON, Chairman 

Environmental Engineering and Science Program 

Department of Civi1 Engineering 

University of Washington 

A. ROBERT FLAAK, Executive Secretary 

Environmental Scientist 

Science Advisory Board 

United States Environmental Protection Aqencv 

Members of the Subcommittee 

DR. J. JULIAN CHISOLM, JR. 

Associate Professor 

Johns Hopkins School of 

Medicine 

DR. SCOTT CLARK 

Professor of Environmental 

Health 

Department of Environmental 

Health 

University of Cincinnati 

Medical Center 

DR. IAN von LINDERN 

President 

Terragraphics Environmental 

Engineering 

DR. KATHRYN R. MAHAFFEY 

Science Advisor 

Office of the Director 

National Institute of 

Environmental Health , 

Sciences ^ 

DR. PAUL MUSHAK 

Consultant and Adjunct 

Professor 

University of North Carolina 

DR. MICHAEL B. RABINOWITZ 

Investigator 

Marine Biological Laboratory 

DR. ROBERT D. ROWE 

Senior Vice President 

RCG/Hagler, Reilly, Inc. 

P£r£i£jigants .from Environmental Protection Agency 

JEFF M. COHEN JOHN H. HAINES 

Office of Air Quality Planning Office of Air Quality Planning 

and Assessment and Assessment 

DR. ROBERT W. ELIAS 

Environmental Criteria and 

Assessment Office 

EXECUTIVE COURT REPORTERS 

DR. DAVID W. McLAMB 

Office of Air Quality Planning 

and Assessment 

(301) 565-0064 
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Others Present 

DR. ALLAN H. MARCUS 

Battelle Memorial Institute 

JAMES GILCHRIST, ESQUIRE 

Representing the American 

Mining Congress 

GALE HOFFNAGLE 

TRC Environmental Consultants 

EDWARD 5EEGER, ESQUIRE 

Representing Lead Industries 

Associati on 

JOHN YODER 

Lead Industries Association 

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"ABLE O^ CONTENTS 

WELCOME AND INTRODUCTION 

Dr. Timothy Cohen, Chairman 

OPENING REMARKS 

A. Robert Flaak, Executive Secretary 

OVERVIEW OF DRAFT DOCUMENT AND SUBCOMMITTEE COMMENTS 

Mr. John Haines 

Mr. Jeff M.•Cohen 

PUBLIC COMMENTS AND GENERAL DISCUSSION--

Public Comments: Gale Hoffnagle, TRC 

Environmental Con su11 an t s 

CASE STUDY RESULTS AND DISCUSSION 

Mr. Jeff M. Cohen 

Dr. David W. McLamb 

A. Robert Flaak 

CHAIRMAN'S SUMMARY 

GENERAL DISCUSSION 

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PROCEEDING S 

CHAIRMAN TIMOTHY LARSON: We will call the meeting 

to order. 

This is the Subcommittee of CASAC meeting on Lead 

Exposure. 

WELCOME AND INTRODUCTION 

CHAIRMAN LARSON: I would welcome everybody here. 

We are glad to have a distinguished group of people to be 

able to review the Exposure Draft document. 

I would like for everyone to introduce themselves 

briefly, including anybody in the audience who would like to. 

My name is Tim Larson. I am the Chairman of this 

Subcommittee. I am in the Environmental Engineering and 

Sciences Program at the University of Washington. I am also 

a member of CASAC. 

As the one leading the charge here, so to speak, I 

am relying on the particular expertise we have here on lead. 

So I am very interested in people's comments. 

DR. CHISOLM: I am Julian Chisolm. I am from 

Baltimore, interested in lead poisoning. 

DR. von LINDERN: I am Ian von Lindern from 

Moscow, Idaho. I have worked on lead smelters. 

DR. MAHAFFEY: I am Kate Mahaffey from National 

Institute of Environmental Health Sciences. 

DR. McLAMB: I am Dave McLamb with the 

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1 Environmental Protection Agency, Office of Air Quality 

2 Planning and Standards. I do related documents on lead 

3 NAAQS, for instance regulatory impact analyses and those 

4 analyses which build it. 

5 MR. HAINES: I am John Haines with the Office of 

6 Air Quality Planning and Standards. I work with Jeff with 

7 respect to the NAAQS review. 

8 MR. COHEN: I am Jeff Cohen. I work with John 

9 Haines. 

10 [Laughter] 

11 DR. MARCUS: Allen Marcus, Battelle, Research12 Triangle Park, North Carolina. I am consultant to Office of 

13 Air Quality Planning and Standards. 

14 DR. CLARK: Scott Clark, University of Cincinnati; 

15 involved in lead studies and soil abatement. 

16 DR. RABINOWITZ: I am Michael Rabinowitz. I am a 

17 geochemist at Children's Hospital in Boston. 

18 DR. MUSHAK: Paul Mushak, consultant, adjunct 

19 faculty at the University of North Carolina. 

20 DR. ROWE: I am Bob Rowe with RCQ/Hagler, Bailly; 

21 and I'm a chemist. 

22 MR. FLAAK: I am Bob Flaak. I am the Executive 

23 Secretary of CASAC. By training, I am a marine ecologist, 

24 but by inclination I have been doing this for a long time. 

25 Members of the audience, would you mind 

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introducing yourselves briefly?' 

DR. ELIAS: I'm Rob Elias, Environmental Criteria 

and Assessment Office at RTP. 

MR. YODER: I'm John Yoder from Lead Industries 

Association. 

MR. HOFFNAGLE: Gale Hoffnagle, TRC Environmental 

Consultants. 

MR. SEEGER: Ed Seeger, attorney for Lead 

Industries Association. 

MR. GILCHRIST: I am Jim Gilchrist, attorney for 

the American Mining Congress. 

OPENING REMARKS 

MR. FLAAK: I have a couple of opening remarks, 

briefly. 

The larger microphones in front of you are the 

ones for the speaker system; the smaller ones are the ones 

for the Court Reporter. If you have something to emphasise, 

don't pull up the Court Reporter's microphone up to you 

because she will jump right out of her chair. 

-Laughter] 

This particular Subcommittee is a Subcommittee of 

the Clean Air Scientific Advisory Committee. Normally, our 

subcommittees are chaired by a member of the full CASAC, 

which Dr. Larson is: one of the seven statutory members. 

The purpose of this Subcommittee review is to 

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review a draft document that was completed back in August on 

the Lead Exposure Analysis, Methodology and Validation. This 

document has been reviewed by the Committee. 

Comments have been submitted to the Agency and 

these comments are part of the discussion for a good part of 

this discussion for today. 

When Mr. Cohen gets into his remarks, he will 

explain a little further why we are doing this and what we 

hope to get out of it. 

For the purposes of those members on this panel 

who have not been with us before, we operate in the public 

eye under the Federal Advisory Committee Act. All of our 

meetings are held in the public. 

Most of the CASAC meetings are fully transcribed 

and copies of the transcription are available usually about 

two weeks after the meeting. 

For any handout material or other documents that 

you don't manage to get a copy of while you are here today, 

please advise me. I will see that you get a copy some time 

after the meeting. 

Tim, do you have anything else? 

CHAIRMAN LARSON: No, not at this time. 

MR. FLAAK: We will turn it over to John. 

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OVERVIEW OF DRAFT DOCUMENT AND SUBCOMMITTEE COMMENTS 

!__._. _!'_:_IQ tJaines 

MR. HAINES: I would like to begin by thanking the 

Subcommittee for their comments. They proved most helpful to 

us. I specially appreciate the time spent preparing them. 

As you are all aware, the Exposure Analysis is a 

key component of our ongoing review of the Lead NAAQS. You 

may recall, the Environmental Protection Agency first set the 

NAAQS for lead in 1978. 

Under the Clean Air Act, the Environmental 

Protection Agency is reguired to periodically review al.l. . 

National Air Quality Standards and the underlying health 

criteria on which they are based. 

As you know, in 1986 the Environmental Criteria 

and Assessment Office completed the update and revisions to 

the Air Quality Criteria for lead, and CASAC closed on that 

document in August 1986. 

In early 1986, we prepared a draft of our staff 

paper which went before CASAC. As part of that session, 

CASAC among other things recommended that the staff refine 

its lead exposure methodology and conduct appropriate 

validation. 

As the result of those recommendations, we have 

produced the draft report that is in front of you today for 

review and comment. 

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Also because we view this document as important we 

have asked Bob and the SAB and CASAC to put together a 

Subcommittee that could specifically focus in on the exposure 

methodology and validation work. We think it's important 

that this receive a very thorough review. 

This will hopefully place us in a position that we 

can move ahead and pull together the next draft of the staff 

paper, and be able to base our projections off the 

methodology set forth here. 

Just for the point of view of the audience, the 

comments submitted by the Subcommittee members have been 

placed in the Docket. So they are available to you folks if 

you would like to review them. 

To facilitate today's discussion, Jeff will 

provide a brief overview of how the exposure methodology 

relates to the NAAQS review. Then he will proceed to provide 

a review of the Subcommittee's comments. 

We have tried to group those comments into major 

categories and our responses to them. So you can see 

collectively what the group's comments were and how we place 

to address them. 

As shown on the agenda, this afternoon Jeff will 

present for the Subcommittee's information some initial 

results from two case studies we have done. There will be an 

opportunity to discuss those briefly. 

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At the end of the day after. Jeff and Dave McLamb, 

we will outline some of the related activities. Jeff will 

talk about some other potential applications for the model 

outside our immediate program; Dave will talk about how it 

will fit into our regulatory impact analysis and that work. 

Finally, I want to reiterate that Allan Marcus has 

been working very closely with Jeff and the staff on the 

development of the exposure model. Bob Elias has provided 

invaluable input to us as well. 

Are you ready to go, Jeff? 

MR. COHEN: Okay. y. . 

_!_._. 1-llL _!_. Qohen 

MR. COHEN: Again, I want to thank you all for the 

comments. We were hoping for the level of detail we actually 

received. It will be very useful to us in finalizing the 

report. 

I want to start out by looking at the Lead Air 

Standard review process. You can see where the lead exposure 

modeling fits in and where our report is today. You can also 

see the different points of CASAC review. 

For example, here at the criteria document 

assessment there is a review of the benefits analysis 

methodology about a year ago. We are planning on going to 

CASAC with a draft staff paper in early 1989. 

This paper will incorporate results of the lead 

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exposure modeling and also fold -in the? overall health risk 

assessment. The staff paper will then serve as a basis for 

the recommendations to the Administrator on alternative 

standards. 

There should be another arrow here, actually, from 

the case study blood-lead estimates to the benefits analysis. 

We will talk about that at the end of the day. 

Just to remind us all, unlike the other criteria 

air pollutants that we have to review, lead has established 

itself in many different pathways of exposure. So it is a 

unique exposure problem for us. 

We need to develop different kinds of exposure 

methodologies. 

This summarizes the different methods that we have 

developed, all accounting for air and well as non-air 

sources, especially rich in future trends in gasoline and 

diet. 

The disaggregate model combines separate 

relationships between blood lead and lead in diet, soil, dust 

as well as air lead from the literature. It is adopted from 

the criteria document. 

We made some changes to reflect newer data. Like 

the aggregate model, it assumes a blood-lead eguilibrium with 

historical exposures. 

While the disaggregate model has an air blood-lead 

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level that really reflects pretty much inhalation, the 

aggregate model slope includes effects of indirect air lead 

exposure: dust and soil. 

The uptake biokinetic model uses age-specific 

intakes on a daily basis from each pathway, as well as agespecific absorption factors. Blood-lead and tissue-lead 

levels are governed by a linear biokinetic model whose growth 

and metabolic factors change with age. 

One of the advantages we see in the model is that 

it can explicitly estimate the effects of relatively rapid 

changes. 

One of the features of the biokinetic uptake model 

is that it requires a large variety of assumptions in input 

data. This lists the parameters that we discuss in the 

report. 

We note, just as background, which ones appear to 

be strongly influential in predicting children's blood leads. 

Those are the ones on which we conducted various sensitivity 

analyses. 

Again, just to remind us, given the available data 

the models estimate average exposure conditions. We are 

concerned not only with the mean blood lead, but with upper 

percentiles of blood leads. 

Given a mean blood lead and the fact that blood 

leads are distributed lead normal, we can calculate 

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distributions using a geometric standard deviation in this 

case. 

The value that we are proposing to use is derived 

from a point-source standard. It is coincidentally identical 

to that which appeared in the criteria document from the NH2 

analysis. 

This list is for the different sub-populations. 

We got several comments on this. There was a little 

confusion which models are being used for what populations. 

For young children, we have three models we feel 

that are available. We are proposing that the uptake .. . 

biokinetic model is the one of choice. 

For adults, given the lack of data on biokinetics, 

for example during pregnancy, we feel that this model is the 

appropriate one to use. One of the reasons not to use the 

more detailed model for adults is that it would require large 

amounts of input data going back in history to account for 

their long-term exposure. 

As Bob mentioneed, the bulk of our talk today, 

this morning at least, will be trying to clarify the issues 

raised in the comments that we received from you. 

We are going to try to go through them quickly, 

but in enough detail that everyone understands not only our 

understanding of the comments, but our responses. 

We have comments on these issues here. We will 

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have discussion later in the day. If anyone wants to talk 

about one thing in particular, in detai'l later, we will be 

glad to put this slide back on. 

I think there is a number on each of the slides so 

we can readily find it. 

We have several comments on the organization and 

presentation of the report, especially on the need to clarify 

the overall plan and how this exposure analysis fits in to 

the review of the standard. We need to discuss a little bit 

more, as well, implications for regulatory actions: What 

models are being used for what populations and why? 

Both of those comments, I think, we will try to 

address with an expanded introduction where we clarify the 

uses of the various models. We are also going to have the 

Executive Summary which I think will help the reader focus in 

on what is important. 

How will differences in blood-lead results be 

resolved? We are planning on presenting results from all of 

the models. 

Again, we are proposing that only the mid-point 

results from the uptake biokinetic model for children and the 

disaggregate model for adults be used for further analyses. 

There was a comment for us to define the bloodlead end points, which we will be more specific on: not only 

the mean blood-lead, but percentage of levels above selected 

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i II blood-lead cutoffs. 

2 II We will talk about some levels later today as an 

3 || example when we present case-study results. 

4 CHAIRMAN LARSON: If any Subcommittee members have 

5 any responses or comments, please feel free to voice them. 

6 || MR. FLAAK: Yes. 

7 II Now, we will briefly go through the comments 

8 classified by the sections in the report, starting with air9 lead where we had some information on non-attainment areas. 

10 That is a good idea. We are going to add some more recent 

11 air quality data to that I will show in a minute. 

12 We can talk about non-attainment problems as well, 

13 then. 

14 There are several comments on the gasoline phase15 down. We will go through these sequentially. 

16 We should discuss that the data on automotive 

17 airborne lead is used interchangeably with data from point 

18 sources. I think Granger Morgan made that comment. He is 

19 | not here today. 

20 We will go back and check that we are clear on 

21 this, but all the data that we use for exposure estimates are 

22 point-source specific: for example respiratory deposition 

23 efficiencies, soil and dust level, and so forth. 

24 There are comments to illustrate the rapid decline 

25 in air lead because of the phase-down. Again, we have some 

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more recent data I will show you on the next slide. 

We discuss the impacts of the decline on exposure 

estimates. Again, we will go back and check on this. We 

note this in several places in the report. We will try to 

highlight that somewhere in the front. 

A comment that in estimating a future baseline 

blood-lead level, we used the gasoline blood-lead regression 

analyses that were done a few years ago and that were 

updated, actually, in the ATSDR Report. 

We should discuss the problems of extrapolating 

those results to point sources in rural areas and whether or 

not it is appropriate to assume the same shape of the bloodlead distribution before and after the phase-down. 

We found that although there is a different 

interset to the gasoline/lead relationship, the slope 

coefficient in the analysis was almost identical for both 

populat ions. 

We are using tests to make the distribution of 

PSD-directed point sources, although it turns out to be 

identical to the analyses result. 

Here is some of the data that we are going to be 

adding to the report. You can see the trends in air quality 

over the last seven years and the dramatic declines that have 

occurred in urban areas in these roadside-oriented monitors. 

This is especially evident looking at the 

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microscale sites which ^re specifically designed to pick up 

high impact lead emissions from busy roadways. We have some 

more recent data on nationwide monitoring that works as well. 

DR. CLARK: What is the middle there on that 

chart? What is that the middle of? 

MR. COHEN: It is called a middle-scale site and 

it has a further setback from, a somewhat less-traveled 

roadway than what the microscale monitor picks up. I am not 

sure of the exact traffic. 

The neighborhood scale site is a smaller roadway 

set back a little farther. .• 

We got several comments on our discussion of soil 

and dust lead and the problems in comparing different data 

from various studies; also, that differences in particle size 

may effect GI uptake lf leaded dust. 

We recognize those problems. One of the things we 

try to do is confine our use of data to those studies that 

collected the upper layer of soil: in other words, that layer 

that children are most exposed to. 

There are, of course, remaining variations in soil 

and dust levels among various locations and that is reflected 

in the uptake estimates, especially in the difference of 

blood-lead soil and dust-lead slits as talked about in the 

criteria document; but we agree that we should highlight that 

a little bit more. 

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There; was a question on why was the data from 

Silver Valley, Idaho. That was a closed facility. 

Nevertheless, there are data in there that we think are 

really useful, especially the soil and dust slit responses 

over time to negligible air lead. 

We are going to try to add some of that data as it 

is available. 

As far as the soil-lead/blood-lead relationship 

analyses that CBC presented, we are informed that it is not 

comparable to the other data that we site. We have asked CDC 

for further re-analyses. 

There was a comment that the Milkie Study 

attributed too much of the soil-leading in downtown Baltimore 

to automobile emissions given the prevalence of old homes 

with lead paint trim. 

We are going to clarify that. We are going to 

incorporate that comment and, also, add some supporting data 

from Chicago. 

These next two basically are suggesting that we 

add some supporting data from Cincinnati and Boston on soil, 

on street and house dust, and on soil/blood-lead 

relationships: add both the Q-HY and Mike's paper. 

There was a comment that the Dutch data of Clausen 

may be unrepresentative. In fact, the results are pretty 

much consistent with the Binder, et al findings from East 

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Helena. 

One thing we did was only use the Dutch data, the 

control data results from the hospitalized children. We 

thought it was necessary to correct the Binder data for 

elemental absorption from the diet of those trace elements. 

In fact, that is something that has been 

incorporated into the ongoing Environmental Protection Agency 

studies in Washington State and the U-Mass/Amhurst studies 

from Calabrese and Gilbert. 

We are going to add those data. Hopefully they 

will be available soon. 

There was a comment that we should reference some 

of the high-soil lead problems around facilities other than 

smelters, various manufacturing facilities. We tried to use 

all the data that we knew about from the literature. 

If anyone has anything in their files, we would be 

glad to add it. 

We need to,clarify, I think, the distinction 

between street dust and soil dust. That concept, I guess, 

appeared in the criteria document which we referred to. 

We can try to clarify that a little bit more. We 

really use that in any quantitative way. 

There were various comments on dietary lead: one, 

that the FDA estimates of lead intake are uncertain and can 

underestimate in a lot of cases. The report to Congress 

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points out a lot of those problems. 

I think we can refer back to that discussion in 

the report for that; but just to emphasize, the dietary 

estimates that we use and that are in that report to Congress 

really represent typical baseline levels. 

They are not intended to capture the high-level 

intakes that certainly exist. 

One of the things we hope to achieve by using the 

GSD is to capture that variability in exposure patterns. I 

think we can add some comparison between the estimates that 

we come up with through Robbs' model and the ATSDR estimates. 

They are actually very similar. 

That is interesting to point out: they are similar 

not only for years, but for specific age/sex categories. 

There was a comment that our water-lead 

projections, based on Office of Drinking Water's estimates 

from their August proposal, were a little optimistic. We 

agreed about the uncertainty in those projections resulting 

from not only the proposed revisions to the standard, but the 

recent solder ban. 

We are just not sure how any of that is going to 

fall out. We feel that, to be conservative, it is probably 

better to maintain future drinking-water levels at current 

concentrations. 

We got some revised input from ODW to support 

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that. 

Most of the data that we cite on dietary lead we;re 

based on post-1973 estimates. Mike pointed out that we 

should note the decline that occurred before 1973. 

DR. MAHAFFEY: Is it possible to get any more 

recent data in the last few years? 

MR. COHEN: On water-lead? 

DR. MAHAFFEY: On diet. 

MR. COHEN: I think we are using 1986. 

MR. HAINES: 1985 was the last that relates to 

that. 

MR. COHEN: 1985? 

MR. HAINES: It is just about time to get the next 

batch available. In fact, we will probably have them within 

the next three months. 

DR. MAHAFFEY: As I understand for the current 

month's data, the numbers are even lower. 

MR. HAINES: There has been a definite trend. 

MR. COHEN: If you know a way for us to get that, 

that would be very helpful. We will try to reference that 

pre-1978 data. 

In fact, that kind of data helped validate the 

total food-level criteria document. So it is a good point 

that we should have it. 

We should note that lipids in lactose may increase 

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lead absorption; and we should modify our statement about 

fasting adults. Their absorption rate is probably closer to 

that of children. 

In both of those we will make those changes. 

DR. MAHAFFEY: Another point in there is that I 

don't think there are many studies on fasting children so 

that that absorption rate could be even higher. 

MR. COHEN: Yes. 

We have several comments on how to improve our 

discussion in paint lead. All of them will be incorporated. 

There is a question on whether or not there is any 

more recent housing data. I don't know of any. If anyone 

knows of anything, again we will be happy to incorporate it. 

We are talking about the prevalence of leadpainted homes across the country. 

There was a general agreement with our approach to 

exclude from the analyses kids with high paint-lead 

exposures. That is an issue that we brought up with the full 

Committee in 1986. They endorsed that approach. 

Although in this report we probably should make it 

clear that we are under-estimating potential benefits to 

children with significant lead exposures, we did do a 

simplistic analysis in one of the appendices illustrating the 

potential impact of paint lead relative to these other 

exposures that we are talking about. We can highlight that 

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• up front a little bit more. 

We have comments on Section V, which is the 

section where we talk about the aggregate/disaggregate model. 

Th ings got a little clut t er ed. 

To make things really simple, we are going to 

remove the table that contains all the detailed data. We do 

want to keep the table after that where we summarize the 

slopes. It clearly distinguishes the disaggregate versus the 

aggregate slopes. 

We should include data on uncertainties associated 

with the slope. This is another comment that Granger made. 

DR. MAHAFFEY: I think there is a fundamental 

uncertainty, too, on the slopes. I think that virtually all 

the data on slopes was obtained from male subjects. 

Since the population that you are.very concerned 

about is pregnant women, it is important to note that this is 

unknown and missing data. 

MR. COHEN: Right. 

DR. MAHAFFEY: It is a major problem. 

MR. COHEN: Good point. Yes. 

There was a comment to compare the studies by 

Chamberlain, et al and Manton to see how their bone-lead 

resorption adjustment compares. Allan has done some work 

recently on thatd, and we can incorporate some of those 

results. 

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Both papers basically run to si milar cone 1u„ions 

by different methods: basically that a substantially fraction 

of adult lead is due to the release of endogenous bone lead. 

We will add more discussion on those two papers: maybe 

anything else that anyone can identify. 

There was a question about the biokinetic model. 

Does the fact that the model accounts for cumulative 

exposures mean that the correlation shows a lifetime average 

blood-lead? 

The cumulative aspect refers, to the long-term 

storage from prior exposure. New York University 

successfully validated the model against autopsy data. Agespecific intakes that we use are designed to allow, of 

course, blood-lead estimates at any age, though. 

We think that that is one of the main advantages, 

again, of the model: that it can capture relatively shortterm changes in exposures compared to the other approaches. 

There was a question where the RYU slope was used. 

It was used in a couple of places: one to 

illustrate, for infants, the relationship between blood-lead 

and uptake. It is also used in the criteria document 

disaggregate model. 

We also refer to it again when we try to estimate 

the impact of dietary lead changes on baseline blood-lead. 

The slope of the RYU data seem to support that. 

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of those data including the rat data. I will try to add some 

of that to the report. 

There is agreement on our approach to focus on 

absorbed lead data to support our absorption assumptions. 

These are relcttively good compared to most other data sets we 

have to deal with. 

We agreed that we should add more discussion on 

the importance of the various assumptions up front. 

There was a comment on the number of hours that 

children are estimated to spend outdoors. It may be 

misleading given winter/summer differences, for example. 

It is true that in trying to capture year-'round 

exposures we are smoothing out seasonal variations. It would 

be possible to distinguish cooler-month exposures. 

We would present those blood-lead estimates on a 

seasonal basis as peak exposure levels, for example. We 

don't anticipate that they would be different, however, from 

the upper bound estimates that we generate now. 

The end result at six years of age probably would 

not be much different. The two-year-old blood-lead certainly 

would be different because of the age-dependent. We are 

looking right now to see if the available data are sufficient 

to do some sensitivity analysis. 

If anyone has any age-specific, seasonal-specifie 

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data, it would be really useful on outdoor behavior patterns. 

Ther« is a related observation that the time? 

outdoors a.a.y be indicative not only of exposure period alone, 

but p1 ay habits. It is true t h at s&ver a1 pa r amet er s i n the 

model ar'B surrogates to summarize more complex variables. 

We should really highlight that point and some 

more recent references that we have. 

Again, smoothing of childhood absorption rates may 

be inappropriate. The reason we did that is that we had no 

data for a lot of the age groups. We thought smoothing was 

the most reasonable alternative. 

The data for children on time spent outdoors 

appears soft. We referred only to an informal parental 

survey. That was an error in our citations. Actually it 

comes from four different behavioral studies listed here. 

We tried to confirm it by some formal survey. 

We should also note that the East Helena Kellogg 

studies found a number of kids who spent more than the 

average hours outside during the summer. 

There was an observation that the predicted bloodleads had a less dispersed distribution than the observed 

blood-leads in the validation exercise at East Helena. 

Again, given the available data, we are predicting average 

exposures. 

We compared those two distributions only to 

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illustrate the quality of the consistency. I don't think the 

model is ever giving to be able, unless we have a Jot mo; e 

data, to account for all the variations in exposures and Uie 

sources that we don't measure now. 

An important point is that the mean blood-lead 

predicted was nearly identical to the observed mean in East 

Helena. 

There was a comment that the GST measured in East 

Helena was similar to that found in Bunker Hill Smelter. 

That is a nice thing for us to add to the report. I think we 

have the appropriate data to derive that. 

MR. HAINES: I think that was in the CDC 

in formation. 

MR. COHEN: Yes. 

There were two comments—again, I think Granger 

made these—that are related: no indication of the expected 

accuracy of the input data; and, are we over-explaining given 

the inherent inaccuracies? 

It was difficult for us to assign a statistical 

uncertainty to the model predictions given the limited data 

that we had to work with. The sensitivity of the predictions 

can be judged by the lower and upper bounds. 

Some key-model parameters that I flashed up 

briefly before were adjusted within the range that we felt 

plausible to better fit the observed limits. 

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29 

1 Did the validation include RUN C? I think, Mike, 

2 you were not clear on that. Actually, RUN C we thought was 

3 our ultimate test. It included all the variables, including 

4 air, dust and soil relationships, especially, that we have to 

5 estimate when we go out to do our case studies. 

6 So the answer is: Yes. But we probably should 

7 make that a little more clear. 

8 Again, we should clarify the discussion on our use 

9 of mid-point estimates in relation to the lower and upper 

10 bound estimates. We feel that the mid-point is a more 

11 plausible and more predictive statistic. .. . 

12 There was the comment that the findings from East 

13 Helena are consistent with other similar in Dallas and Bunker 

14 Hill with the model proved with more discrete exposure 

15 estimates: in other words, looking at block-by-block 

16 exposures as opposed to census track patterns, for example. 

17 I hope we can note that by referring to some of 

18 the results from Bunker Hill. I don't know if that is 

19 available yet. 

20 We had discussion on how air quality interpolation 

21 procedures will be used. In East Helena, we had a more dense 

22 monitoring network than we usually have. So we were able to 

23 compare interpolated smooth monitoring values versus model 

24 data from the ISE dispersion model, which of course is what 

25 we are limited to when we model future scenarios. 

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1 II It turns out that the results were fair 3 y similar. 

2 || When we do our ca^s studies, though, we are going to u;;e the 

3 || ISC dispersion modeling. 

4 || This is something we talked about earlier. We 

5 || will add more discussion—hopefully we will hear more today--

6 II on how the approaches that we talk about may be applied to 

7 || other lead exposure assessments. 

8 We are hearing a lot of interest from other 

9 programs, not only within the Agency but outside, on using 

10 these tools for soil-lead, for example, assessments. 

11 In East Helena, we looked at area one, which was 

12 within a mile, and area two, which was a little farther out. 

13 There appeared to be some differences in the slopes that were 

14 derived from the model. 

15 The comments probably related to unmeasured 

18 variables: demographic or nutritional factors, for example. 

17 We agreed that those variables should be considered. 

18 One finding in East Helena was that there was no 

19 significant improvement in predicting blood-lead after 

20 including dietary habits and income, for example. That was 

21 attributed to the low prevalence of detectable lead paint 

22 there, and the relative homogeneity in housing quality and 

23 social status. 

24 That is another reason why East Helena represented 

25 a good validation case. I think similar results were found 

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in Bunker Hi 11 . 

In other areas, these factors are potentially very 

power determinates of blood-lead; but we stre not going to 

have the data that is necessary to incorporate that. That is 

one of the reasons why we ar<s using the geometric standard 

deviation, for example, to estimate the complete distribution 

of blood-leads. 

We just can't capture all the variability with the 

modeling that is available at this time. 

There is a little confusion,, probably, about our 

baseline blood-lead projection in the aggregate model. _If. 

extrapolated, that level would suggest only 20,000 kids would 

have blood-leads above 10 in 1990 versus over five times" that 

now just living in inner city areas in the ATSDR Report. 

I guess we need to emphasize or be clear that the 

baseline blood-lead projects represent rural non-air exposure 

with minimal paint lead. 

DR. MUSHAK: The point of the comment I made there 

was the fact that part of it gives you some idea of how much 

of a population of children you are going to do something 

for. 

MR. COHEN: Right. 

DR. MUSHAK: What size of population you are not. 

MR. COHEN: Yes. We probably should add that. 

DR. MUSHAK: If you work through the thing as I 

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gav e i t t o you , you fin d tha t one-sevent h of al l th e childre n 

a r e goin g t o hi a v e b 1 o o d -1 e a d 1 e v e 1 s p r o b abl y a b o v e 10 

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A l l of thes e 1ow-SES inne r cit y children , stil l i n 

1990 , I would imagine , would hav e blood-lead s nea r 10 or 

above . 

MR. COHEN: Yes. 

DR. MUSHAK:: So the fact is that that you either 

choose to write them off complete and say, "That is HUD's 

problem" or "That is some hybrid problem of HUD," or you try 

to look at a separate scenario for them and say that even a 

small amount of air-lead adjustment will help them. 

MR. COHEN: Yes. The other thing that probably 

would help is, when we add the prevalence of children living 

in the vicinity of these sources,— 

DR. MUSHAK: We talked last night about the fact 

that many points sources are in urban areas which multiply 

impact these same children. 

MR. COHEN: Yes. 

DR. MUSHAK: You are only going to catch a part of 

it. 

MR. COHEN: Right. 

On Hispanic children, we would love to have that 

data. We were not able to get the summary data so far. We 

have been trying for a couple of years. 

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things on that. I don't know why. 

DR. MUSHAK: Let me interject our experience. 

We tried to get Hispanic data for a report to 

Congress. The super-perfectionists at National Center for 

Health Statistics were unhappy with how the data was 

avai1 able. 

Plus, I believe, there was some unfortunate early 

political capital that was made of that data base earlier. 

So they are very antsy about the quality of that. 

MR. COHEN: Yes. ; • . 

DR. RABINOWITZ: So because the quality of the 

data may not be good enough, it may not be available at all? 

DR. MUSHAK: That is their version. I am getting 

information second hand. We have not seen the run. 

That has been our experience, too, in this. 

MR. COHEN: There was the comment that older 

populations may not experience the projected declines that we 

are predicting because of their high historical exposures. 

We really need to emphasize that point up front, 

although the one opportunity we have, really, to make that 

adjustment is using the bone-lead resorption adjustment from 

Chamberlain; but we will add some more discussion on that. 

DR. MUSHAK: I am not sure Chamberlain does the 

osteopor ot i c women,— 

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MR. COHEN: No, he does not. 

DR. MUSHAK: —which would be a multiple of, like, 

2 or 2-1/2. 

DR. MAHAFFEY: I think you really have to make 

that point strongly. I did not go back to Chamberlain of 

1983, but I really don't believe that there is that much data 

on the t op i c. 

I am concerned that we are getting the type of 

model validation in here that does not deal with the fact 

that there is a lot of biological/physiological data that are 

absolutely missing. ., . 

DR. MUSHAK: Chamberlain's still in the 1.3 

factor. Didn't that still relate back to the isotopic? In 

other words, half went to the bone and then of that half came 

out: 25 percent. 

MR. COHEN: Yes. That was the trace. 

DR. MUSHAK: So that is not even good for us. 

That is still a short-term bone resorption response. 

MR. COHEN: Yes. 

DR. MARCUS: There was some more recent work that 

Chamberlain did in the 1985 paper. It was a synthesis of 

data from a variety of different sources: a compartmental 

kinetic-type model. 

It still came up with an estimate of 20-some 

percent for after some 50 years of exposure, pumping the lead 

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into the bone. 

DR. MUSHAK: Manton's data is probably the best 

for it, would you say? 

DR. MARCUS: Manton's data is extremely suggestive 

of the importance of this from a quantitative point of view. 

Manton had to make some assumptions about the 

contributions from concurrent, exposures. 

DR. MUSHAK: As did any modeling used by 

Chamber 1ain. 

DR. MARCUS: Well, Chamberlain had to make a 

different set of assumptions. I would say that either value 

has sort of been cast in marble; but they are both reasonably 

in concord that a substantial fraction, certainly upwards of 

20 percent in adult males who have had substantial historical 

exposure to lead, has created a bone pool or bone reservoir 

of lead that is going to be coming back out, and will be 

detectable in blood-lead. 

DR. RABINOWITZ: Another set of data that could 

bear on this is from occupationally-exposed people who have 

much higher blood-leads and much higher bone stores, and 

watching the very slow rate in decline of blood-lead in that 

population. 

It speaks a little bit about how available bonelead is for later blood-lead elevations. I don't know how 

applicable it is because they may be kind of pathological 

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cases in that their bone-leads ars so.high. I don't know if 

you want to use that to address the general population. 

But it says something about rates, anyhow. 

DR. MARCUS: Yes. They have a long-term half-life 

in blood from lead resorption in the bone of 5-pointsomething. 

MR. COHEN: We also looked at the Silver Valley 

study a little more superficially than East Helena, but the 

control areas there did not have measured air-lead levels and 

we will note that. 

We got comments on our estimated relationships, 

between air, soil and dust. It is difficult to quantify 

temporal changes in soil and dust, especially in some sites: 

for example, highly-contaminated areas where current air-lead 

effects are neglible, in closed facilities; or clean areas 

where soil dust accumulations may be non-linear. 

Then we used all the available data from a wide 

variety of point source areas that reported quality-assure 

protocols. 

Based on the limited longitudinal data, we have 

21 D some assurance that the relationships are, in general 

22 

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plausible. 

The uncertainties, however, regarding the temporal 

patterns of soil and dust changes are the reasons that we 

decided to use two different assumptions: one, where we keep 

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soil-lead constant over time; and the other where we vary 

soil-lead with a i r -1 _• a d. 

When we talk about the case study results, you 

will see how different the blood-lead estimates are under 

t h o s e two a s s u m p t i. o n s. 

The non-linear relationships that we looked at for 

the data sets that we examined were not any better than the 

linear models that were used. 

Yes, the soil and dust equations do include 

historical deposits of lead from prior deposition. "Are the 

equations in Appendix B intended to be used recursively?." . 

The answer is no, simply. 

Equation 3.3 for dust-lead is intended to be used 

if only air-lead is available; and 3.2 should be used for 

dust if both air-lead and soil-lead are available; and we 

will add discussion on that. 

There was a question about our discussion in 7.7: 

whether or not that implies that the air-quality standard 

should be established for certain incorporated soil- and 

dust-lead levels or that soil should be reduced to a 

particular level. 

That is an interesting policy issue that we might 

want to talk about later; but, analytically, our intent was 

to account for all pathways, including elevated soil and 

dust, that already exist around point sources. 

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The relationships were derived from areas 

excluding those closed facilities that we talked about: no 

negligible air-lead, but highly-contaminated soil and dust. 

Similarly, the air/blood-lead slopes that we had 

from children are derived from operating point sources. 

There was a question in air-lead monitoring: 

whether or not we plan on rearranging our monitoring network 

away from mobile sources and focus on stationary sources. 

The answer to that is: Yes. 

That is something that we will discuss when we 

actually propose the standard; but clearly there is a need to 

do that. 

There was a discussion on the height of monitors 

as it relates to the breathing height of children. It is 

important that we should note this in the report: that any of 

the data are from roof-top, real-world monitors. It is not 

available to get personalized monitoring for children. 

We can add further references from the criteria 

document on the vertical gradients, but most of that data is 

from mobile-source situations. 

That is about it for our summary on the comments. 

The next step for us is to finalize the exposure report by 

incorporating the comments. 

That will, in turn, become a source for the staff 

paper case-study analyses that we will get into in early 

J' EXECUTIVE COURT REPORTERS (301) 565-0064 
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1 1939; and also will become a reference for the regulatory 

2 impact analysis, as well as other regulatory analyses both 

3 inside and outside the Environmental Protection Agency. 

4 Hopefully, we will have time to discuss those 

5 other analyses at the end of the day. 

6 Thank you for bearing with us here. 

7 CHAIRMAN LARSON: Thank you, Jeff. 

8 We have not had a lot of back and forth 

9 discussion. So we seem to be breezing right along here. 

10 Perhaps we can take the time at this point to ask 

11 for general discussion. 

12 MR. FLAAK: We are running a little ahead of 

13 schedule. 

14 CHAIRMAN LARSON: Let's have the public comments 

15 now. Gale, are you prepared? 

16 MR. HOFFNAGLE: It is a little early, but we can 

17 talk about our comments. 

18 CHAIRMAN LARSON: All right. Would you, please? 

19 

P_}_>Ii£ ££_M__:Q_;_?i Gale HoJ.fnagie.,. JRC Environmenta l 

20 £2D5_}I_;_}0_;3 

21 MR. HOFFNAGLE: I am Gale Hoffnagle from TRC 

22 Environmental Consultants. I represent the Lead Industries 

23 Association. 

24 We have prepared a set of comments about the 

25 exposure assessment methodology. We have been working with 

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Jeff Cohen and John Haines since the last CASAC meeting. 

We reviewed the staff paper and provided what data 

we could, and analysis that we could to be helpful to theprocess. 

We have taken a look at this document. I am sorry 

I did not use the invitation to get comments in by September 

9, but we are a little behind the eight ball here. 

In recognition of your desire to have the public 

comments be different than what is in the written text, I 

think there are really only two major differences we have 

with the exposure assessment methodology at this point.** I 

would like to highlight those. 

We agree generally with the assessment 

methodology. We feel that it goes a long way toward 

overcoming some of the objections that we had before, and 

that it includes a lot better set of data and more realistic 

conclusions directed at sources rather than a lot more 

generalized problem. 

We also agree with Jeff's statement, and the 

conclusion here basically, that the uptake biokinetic model 

is the right way at this point to go after the problem: that 

it offers some real advantages in terms of dividing out among 

the source categories where the problems lies; that is it not 

available in the aggregate or the disaggregate model. 

Our concern has been primarily in two areas: those 

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are in the actual relationship between air-lead, and soiland dust-lead that has been generated here. 

I am concerned about it from the point of view of 

the selection afterwards, after the fact, of the data that is 

in Table A-3, the Appendix table which lists all kinds of 

sets of data, rather than going ahead and using the East 

Helena results. 

I think you developed a relationship at East 

Helena that is correct and it is accurate. It uses a larger 

data set to develop that relationship. 

So we would propose that you do that. ± . 

I have prepared to plots here that, I think, help 

us focus—you have copies of them—on the issue. I have 

taken the Table A-3 data, which represent all the sets of 

data that could be looked at, and looked at individual points 

on the Table A-3 data. 

I have taken out of that the ones that were-agreed 

to in the paper, and we had agreed that those should be taken 

out; but I have also taken out the ones that are not pointsource related. So all we have left is the point-sourcerelated ones. 

I took out the ones from Bartlett, the five small 

t 

copper-smelter type facilities. All of those air-lead 

concentrations are low so I don't think they add much to the 

slope. 

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But in their paper, they could not find any 

relationship between the air- and soil-leads at al1. If they 

.cannot find it in the paper itself, it is hard to use it in 

an extrapolation like this. 

Here is our air-lead/soi1-lead versus airlead/soi1-lead concentration basically in thousands of 

micrograms per gram ppm versus ambient air concentrations. 

We have a range from 2 to 4. I don't think that 

we should concern ourselves with the concentrations that are 

greater than 4, let's say. So I removed the ones that are 

high; and, also, the soi1-lead concentrations that are real 

high. 

I think these represent different kinds of 

c i r cumstane es. 

These are the different data sets for point 

sources. What is interesting about them is the Toronto data 

and the Brussels data. This is an Omaha data point, this is 

another Toronto data point, but all the ones that are up here 

on top represent urban point-source situations: Toronto and 

Brussels. 

The ones that are on the bottom represent rurals, 

in essence. This line is the line of blood-lead/soi1-lead of 

15 times 579 air-lead that was used in Table 4-1 and used, 

finally, in the analysis; and this line is the line from East 

Helena. 

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If I understand it correctly, Jeff, the line from 

East Helena includes a lot more data points than the data 

points that were on Table A-3. There are some East Helena 

data points here—this one, this one, this one, this one, and 

this one—but those are different data points than the one 

you used to develop this line or this slope. 

MR. COHEN: That is right. 

The summary data that we used from the literature, 

though, is home-specific. So, in fact, they do include more 

homes than is reflected. The individual data points from the 

different studies represent a large number of homes. 

MR. HOFFNAGLE: A large number of average sets of 

homes, right? 

MR. COHEN: Yes. 

MR. HOFFNAGLE: My point is that the slope of this 

line from East Helena is derived differently than just these 

five points. So if you tried to draw a line through the East 

Helena points up here, you would not get this one. 

We have a tendency to believe that most of the 

situations that we ought to be talking about, rural-area 

situations where we don't have automotive-lead input or 

paint-lead input and so forth, ought to consider this East 

Helena line: that it is better for them. 

I also dotted in the range of values that is used 

ono Table A-4 by plotting them in. What I don't know, and 

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what I would like to ask, is: How were the rarige of values 

set for soil and for household dust? 

On Table 4-1 you have a. range, but I don't 

understand from the document how the range was developed. 

MR. COHEN: In Table A-4. 

MR. HOFFNAGLE: Table 4-1 has a range. Appendix A 

gives us a mean value and a slope, but I don't know how the 

range was developed. 

Table. A-4 has a range of soil dust and household 

dust. 

MR. COHEN: Not Table 4. 

MR. HOFFNAGLE: 4-1. 

CPauseD 

MR. COHEN: Line 12? 

MR. HOFFNAGLE: Yes. Lines 12 and 13. I don't 

know how those ranges were developed. 

In the staff paper, we knew because it came from a 

table in the Appendix, how the ranges were developed. 

DR. MARCUS: I will have to go back and verify 

this, but I think these ranges represent the 95 percent 

confidence intervals that were derived from that. 

MR. HOFFNAGLE: Okay. That's fine. 

In order to reproduce it for this slope, which you 

have not done, I would like to reproduce the range for the 

East Helena slope. I did not have the methodology, but it is 

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95 percent confidence so I will have to have the data, too. 

It i. s' important bs:HUhr the range of values that 

result on Table A-4--1 are a substantially larger total range, 

although somewhat shifted down, from those in the OAQPS staff 

paper from two years ago. The ranges are larger'. 

For instance,, at 1.5 micrograms per cubic meter, 

the highest value that appears on the table is substantially 

larger than the highest value that appeared in the original 

OAQPS staff paper. 

So if one is to look at the top of the range and 

made one's decisions on the top of the range, it gives you a 

lot higher number than if you are just looking at the mean. 

I would suggest—and I think the suggestion was made before— 

that you put the mean value in this table so people can look 

at it, and then the ranges and standard deviations. 

MR. COHEN: Yes, we should make that a little more 

clear. 

Again, the equations in A-4 are the ones that we 

intend to use with the case study. 

MR. HOFFNAGLE: From the East Helena data? 

MR. COHEN: We are proposing to use what we call 

the SPTA, just the point-source data and include, as you did, 

all the urban-specific data. 

MR. HOFFNAGLE: I guess my point will be come more 

clear when you look at the second figure, which is the 

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household dust figure, to say that we 'think the East Helena 

data-—which you spent a lot of time developing and 

generating—is a better data set to use. 

This is household dust versus air-lead. Here is 

the one you picked. Here is the East Helena one which, 

again, was derived from, a different set of data, or in a 

different methodology, than the points that are on this 

cur ve on this line. 

As you can see, it goes substantially over at 

least the data sets that I picked from,Table A for you to 

look at; and the mean and range is substantially higher; -than 

the bulk of values that I have considered for using the data. 

This data point from El Paso, which is hardly the 

most accurate data set that we know about and, I think, is 

doubtful, I think weights this distribution if that is what 

has happened; and I am not sure that that is what happened. 

MR. COHEN: We tried to throw out this -outline. 

We tried to discuss it in the paper, I thought we did. We 

will go back and take a look at that. 

MR. HOFFNAGLE: Okay. Please take a look at this. 

I think, looking at it this way, I am concerned 

about it. What concerns me, of course, is that these 

household dust-lead numbers do drive the final answer. In 

other words, the household dust, because the children are 

inside more than they are outside, does tend to drive that 

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final answer quite substantially. 

MR. HAINES: If I follow your argument, are we 

focusing in on a rural situation? Keep in mind, we have? to 

be:: concerned not only with primary smelters located in rural 

settings such as in East Helena, but we also have to worry 

about stationary sources, secondary smelters oriented in 

urban areas. 

I am not quite sure in my own mind that we can 

exclude point-source urban data from the analysis as you are 

suggesting here and focus only on East,Helena because I am 

not sure that East Helena is representative of these other 

settings. 

MR. HOFFNAGLE: I agree with that; but if you are 

going to do a separate model for the urban area, then you 

need to include the other sources of lead in that urban area. 

You need to be much more specific about it. 

MR. HAINES: Are you suggesting, then, Gale, that 

for a rural-oriented source, we use East Helena for case 

studies, then use the total data set or segregate out the 

rural and only use urban point-source data or more urban 

locations? 

MR. HOFFNAGLE: I am saying that they are very 

different data sets and it might be more useful to look at an 

urban data set that was more convincing. 

I like to look at a case study like you have done 

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at East Helena and go through it and understand it 

completely. Rather than using the STPA data set, if you 

took, for instance, the Toronto data set, which I think is 

pretty good, and looked at Toronto specifically—you 

developed an urban model for Toronto as compared to the; rural 

model for East Helena—I think that would give us more 

information than the STPA data set. 

MR. COHEN: Actually, Gale, one thing that 

probably was not clear when we did derive the air/soi1/dust 

relationships in Appendix C, we excluded those data that were 

not collected around point sources in urban area. {. 

I think the data sets that we looked at were 

pretty similar to the ones we have here. You excluded the 

Bartesville, Oklahoma: that suite of data. 

MR. HOFFNAGLE: Right, but all of that data is 

right down in here, along this line. 

MR. COHEN: Right. 

MR. HOFFNAGLE: I think it was clear in the 

document that you threw out five sets of data. I went back 

through my Table A-3 and put an "X" next to the ones that you 

said you threw out. 

Did you eliminate other data sets from that table 

before you did the progressions? 

MR. COHEN: Yes. 

MR. HOFFNAGLE: We need to know that. 

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MR. COHEN: Those data were the ones that were 

just urban data. I thought we talked about all of them in 

our discussion after Table A-3, but I don't think we got all 

of them, like the? Janson table, for example, which was 

collected in Chicago. 

MR. HOFFNAGLE: Okay. 

MR. COHEN: So all these were the point-sourcespecific data. We did group primary lead smelters with 

secondary lead smelters and battery plants. 

MR. HOFFNAGLE: Okay. 

DR. RABINOWITZ: Could I ask a question? : . 

MR. COHEN: Sure. 

DR. RABINOWITZ: I am not even sure to ask this 

of, but in trying to get this relationship between soil-lead 

and air-lead, I have a bit of trouble understanding it 

because I imagine air-lead goes up and down, maybe hourly or 

daily or seasonally, where soil-leads, I imagine, just 

accumulate with time from fall-out and such. 

So I am kind of doubtful of the exercise of 

relating the two just because of the mechanism, I imagine. 

I am wondering: Has anyone tried relating soillead and air-lead where you look at the integrate air-lead in 

some way? Say, "Okay. We have had this air-lead for ten 

decades. We have had this air-lead for two years." 

Maybe this might explain why things are not all on 

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a perfec t s t r a i •- h t 1 i n e. 

MR. HOFFNAGLE: Jeff and I both have fa*en looking 

for a year and a half or two years, as well as others, to 

find an appropriate data set to do that with. 

I think we all understand—and I listed iri my 

comments there—the complexities that are involved. .In fact, 

I am very concerned about this complexity, especially the 

temporal changes. 

We know in the temporal process the deposition 

occurs over a long period of time in the soil: it builds up. 

What, exactly, are those? 

What is done here is to try to give us a quick 

methodology, a simplified methodology without the time -

dependency to make a relationship. It is very empirical. 

That is what has happened. We have done the best 

we can. 

I think there are lots of complexities to it. 

There are lots of reasons why we may be creating a problem, 

why we may be inappropriately effective at one location or 

another because of the empiricism that we are developing 

here. 

I think generally we would like to have more data. 

I believe more data is coming. 

We are still trying to obtain the data from Fort 

Peary in Australia where they have done a large study over a 

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long period of time and we may be able to get some more 

information. 

But t o say t h is is an i nst ant aneous r el ati on shi p 

is wrong. It is a lot more? complex. 

DR. MARCUS: I would like to add a few comments on 

t h is r e1 at ion shi p. 

It i s comp 1 ex. Some of tiie i n f or mati on we wou 1 d 

have liked to have provided was left out, otherwise we would 

have had a document four times longer than it is now. 

There was some discussion there, a search for an 

underlying theory, in which we pointed out that the 

relationship between air-lead concentrations and surface-soil 

and dust concentrations depends also on the amount of nonleaded particulate in the air; and even if you had exactly 

the same concentration of leaded particulates in the air in 

one location, but the amount of non-leaded particulates that 

was falling out was larger in one location than another one, 

you would have a lower surface-soil concentration. 

I don't suggest adding unleaded dirt to the air so 

as to dilute the soil-lead concentration; but that is one of 

the concerns. 

So a completely general universal relationship is 

obviously not one we are looking for. 

For technical reasons, the East Helena slope may 

be eventually less relevant because of what could be called a 

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measure.'me?nt erro r or errors-in-?variable s problem in fittin g 

regressio n oiOcitiO s; tha t is , th e air-lea d measurement for each 

househol d or for' each block tha t was tie d t o a soil - or dust -

iest! (iiecsur ement in East Helena at a particula r location . 

Even though the? network of monitors in East Helena 

was more dens e than iri any othe r location—whic h i s one of 

t h e reason s we selecte d thi s for a validatio n study—th e air -

lea d measurements could hardl y be sai d t o be so dens e a s t o 

provid e a very complet e imputatio n of an air-lea d for each 

bloc k in East Helena . Ther e just were not that many 

monitors. , . . 

In fittin g thos e relationships, I have a concern 

tha t th e air-lea d variable , the input or predicto r or 

regresso r variabl e in thos e relationships, had a considerabl e 

amount of uncertaint y in it . 

It is known that the technica l effec t of an 

uncertaint y and imputation i s t o attenuat e or flatte n th e 

regressio n slopes. 

There are about a thousand article s on thi s 

regressio n attenuatio n effect . It has also , I believe , been 

discusse d by Brumkreath and his author s in th e Am.e_.L_._t_. 

jjojarrjal o ! Epidemiology

 i n

 1987. 

We believe , for the East Helena data set , i t i s 

probably a not-trivia l factor in reducing th e estimated 

slope . 

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The mean values that were used in the 40-odc . — -. j : •: i-. 

data points are including, of course-, a range of locations. 

It is the usual concern about having one or two air-lead 

monitors representing a rtKiion or metropolitan area. 

What you have on the other side of that is an 

aggregate measure of soil or dust congregation, which is an 

average. In terms of the amount of proportionate amount of 

uncertainty in those numbers, taking into account the fact 

that there are a lot of reasons why there should be 

differences in those ratios from one location to another we 

believe that those probably provide a more valid relationship 

with the uncertainties there primarily representing 

differences from one urban or rural location to another urban 

or rural location. 

The analyses really are doing somewhat different 

things. The SPTA analysis, we believe, is more generalizable 

to more different kinds of conditions. 

MR. HOFFNAGLE: I have two comments. 

I disagree with that because I think East Helena 

is the best data set to use and it works better than anything 

else. 

The result is that your slope, wiht 50 parts per 

million as the constand and 579 multiplied by the ambient air 

quality, means that at 1.5 micrograms per cubic meter you are 

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lead concent r a t i o n is d e p e r. d e n t u p o n i m m e d i a t e d e p o s i t i o n. 

From that point of view, the slope that you have 

chosen says that the soil-lead concentration is determined 

directly by the air-lead concentration with only 50 parts per 

million being soil that was there. 

To me, that is the far most conservative way that 

you could go in that calculation. I guess it could be 1,000 

parts per million micrograms per cubic meter, but with a 

constant of only 50 ppm that says most ground is 50 ppm and 

everything else comes from the air, is deposited from ambient 

air. 

The second part of it is that as we move toward 

controls of smelters and all sorts of lead point sources we 

are changing the particle size distribution of those 

emissions radically. 

Any relationship we develop now, I think, changes 

the particle size distribution for a number of reasons: 

because the deposition footprint changes, where it is 

deposited changes, as well as the particle size distributions 

that are important. 

DR. MARCUS: The locations that were in the STPA 

were locations that had had fairly long histories of 

deposition at concentrations—I guess you would have to say 

historical integrated concentrations—that were not orders of 

magnitude different over the period of time that was felt to 

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be relevan t t o th e ...oil _ -i _ L.'t'U'.J sit ion 

Thc-'i" e ar „ . hterest ir;g questions abciut what 

would happen if the; _ were an abrupt change in air 

concentrations and a time scale over which a different soil 

and dust concentration would be achieved. 

W e h a v e a 11 b _ e n 3. o o k i n g f o r d a t a that might g i v e 

us an insight into this. There may be analyses for theoming 

from the Kellogg, Idaho area in which a smelter there has 

closed down to study the changes in these concentrations over 

time as a result of an abrupt change in an air-lead 

concentration. 

I am not aware of other data sets that are as 

useful in answering that question about the effects of these 

changes. Maybe you could answer that. 

CHAIRMAN LARSON: We will move ahead. Then 

perhaps, after the break, we can have a more wide-ranging 

discussion. 

MR. HOFFNAGLE: The other point is that we fail to 

see why you don't use the Clausen, et al number for dietary 

intake update: dirt, congestion and the like. It is 56 

milligrams per day. 

The second document that you have there is use of 

the uptake by the kinetic model at four different smelter 

sites where we have some data. It is the bound document. 

That document used the available data with the 

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update biokinetic mode?! to try to develop to see what the? 

relationship was around smelters for four smelters and we? did 

Toronto twice, before and after the quote/unquote clean us. 

The* most useful thing we got out of that is that 

be back-calculated a number that is vsry close to Clausen. 

Whether or not you believe in back-calculation, it seems that 

55, 60 milligrams per day represents something in the real 

world around these smelters as much as it did in Clausen's 

study, which has been discussed in other ways. 

I don't think using Binder, et al or subtracting 

Clausen from Binder, et al is the right way to go. We^ would 

urge that you go ahead and use the Clausen as the ingestion, 

rate supported by our study here. 

For both the leaded-soil issue and for this, the 

Lead and Soils Conference that was held back in May, we 

understand, is to be published in December. So we will have 

that data available in the journals at that time.-

CHAIRMAN LARSON: Thank you, Gale. 

Any questions? 

MR. COHEN: Yes. I just want to let Gale know 

that we made some changes to the uptake estim-ates since he 

did that earlier analysis a year or so ago. 

MR. HOFFNAGLE: Yes. Changes that are in your 

document here? 

MR. COHEN: Yes. 

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1 MR. HOFFNAGLE: Did I understand that you too!: the 

2 Binder, et al and subtracted Clausen, et al from it to come 

3 up with something like 100 milligrams per day and a range? 

4 MR. COKEN: Right. I am talki ng about other 

5 par a;net'_rsf though, as well that you might want to make those 

6 adjustments to based on this report and see if it still 

7 compares well. 

8 The other thing is that you don't have the 

9 biokinetic model itself, other than, I guess, the 

10 relationship between daily lead uptake, assuming constant 

11 uptake, and correlated with blood-lead. 

12 I think you might get a different result if you 

13 plug in different daily intakes as the kid ages and allow the 

14 dynamics of lead movement through the body be accounted for 

15 as the model does. 

16 You may get a different result. 

17 We did look at alternative soil ingestion rates, 

18 including going down to that range, in East Helena. We found 

19 that the numbers that we have actually arrived at here 

20 predict better. 

21 We under-predicted blood-lead in East Helena using 

22 that. 

23 MR. HOFFNAGLE: The uptake biokinetic model has a 

24 lot of variables in it. Which one you play with to have it 

25 match the blood-lead is a Hobson's Choic e most of the time. 

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that drives the tota 

What that comes from is the d^iv: 

model, though. That is thi. oi 

number. 

I would just like to add, I went back i"if .v;;h and 

in the results is a table that shows you two changes tha' I 

have: using the East Helena air-lead to soil- and dust-lead 

number; and the 56 milligrams per day ingestion number. 

These are the numbers that that update comes to, 

and they are very different. These ans close to the mean 

values. They are much smaller. 

I didn't know the methodology to get the ranges 

that we talked aboutm before, and we can do that. But we 

would opt that that is a better way to approach the 

situation. 

I also wanted to say, on ingestion rates, that the 

Office of Toxic Substances is looking at ingestion rates as 

well. I would just make sure that you are aware of that. I 

sent them a copy of our report on ingestion rates. 

CHAIRMAN LARSON: Okay, Gale. Thank you for that. 

Do you have any further questions? 

DR. RABINOWITZ: Maybe I should say this now in 

case I forget it later. 

About using smeltered data to establish the 

regression line between air-lead and soil-lead, I just want 

to get a sense from people. 

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Is there a problem using that type of data? In 

practice?, smelters don't always work nice and smoothly. 

Sometimes you have a fire in a bag house and sometimes things 

happtr'n and you suddenly get a whole bunch of lead coming out 

that may not show up in the air data, but it does show up in 

the soil data. 

I wonder if that is not another complicating 

factor. I don't know if that is a real problem or not. For 

me, it is an imaginary problem. 

If all of these problems are real enough, if you 

just throw out the idea of regressing soil-lead and air-lead, 

say you are not going to do it, can you still establish a 

standard? Can you still write an air-lead standard without 

correlating air-lead and soil-lead? 

Is there still some other approach to getting at 

what we are trying to do? 

MR. HOFFNAGLE: My answer to that is that 90 

percent of the changing in blood-lead that is being projected 

here is a change in soil-lead concentrations so that my 

answer is no. You cannot set it unless you have some 

understanding of what that is. 

I will respond that, yes, sometimes you blow a bag 

house and there are accidents, et cetera, that change the 

soil-lead concentration around the facility by a lot. 

I think to go back and put it a different way is: 

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'ind a relationshi p between ths- two 

If we cannot demortstrat e .-. relationship , which neithe r Jeff 

nor I can do,- between ai ; -lead s and depositio n tha t is , 

deposite d ] ead—-on th e ground where we have tha t kind of 

data , we cann c 

If we cannot find a relationshi p between air-lead s 

and deposite d lead , how can we assume tha t we wil l be abl e t o 

find a relationshi p between tha t and th e soi1-lea d 

c on c en t r a t i on ? 

You need more data . 

CHAIRMAN LARSON: I don' t want t o sto p th e flow of 

scientifi c thought , but I thin k with thi s food for additiona l 

discussio n prio r t o lunch why don' t we tak e a 15-minute break 

and furthe r tha t discussion . 

Thank you, Gale . 

MR. HOFFNAGLE: Thank you. 

[A brief recess was taken.] 

CHAIRMAN LARSON: I think we will pick up where we 

left off on the particular topic of the soil/air 

relationships. Ian ha- some comments he would like to share 

I with us at this time. 

DR. von LINDERN: I had basically two comments on 

the East Helena information that was presented, one just to 

echo Mike Rabinowitz' comment the soil levels are almost 

assuredly related to the history of the facility and not to 

the current measurements that we see. 

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.)' • 

Tf vou would go back and look either at cortrol 

equipment or at historical monitoring data in the vi •: I. r.i. ty of 

these smelters, there have been much, much higher 

concentrations in the past, the bulk of it prior to 1975 and 

it continues along at a lower pattern until about 1978 to 

19S0 until controls came in in response to the NAAQS. 

So it is a historical problem in relating it to 

current concentrations which is a special difficulty. 

As I understand how that soil information was 

collection, with the East Helena data I believed they used 

the same methodology we used in Bunker Hill. That -• 

concentration is the top inch of mineral soil. 

In most cases, that is at least an inch deep in 

the soil profile. What we call the litter layer or the 

vegetative layer of the sod is on top of that and we sample 

that separately. I believe East Helena did as well. 

What is measured there has a temporal factor with 

it, as well. It is material that is at least a couple of 

seasons old if not older, and the most recent material is 

probably related to the current air concentrations that are 

used and would be, more appropriately, in the litter layer. 

That was my comment about explaining soils dust 

versus soils street dust situations. In at least most of the 

smelter studies, that soil value is not a surface soil 

sample: is the top inch of the minerals. 

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DR. M AH AFFE Y: I ha ve some sor t o f b r oad gen er a 1 

comments and c.;uest:!. ons. would you want t o proceed wit h thos e 

! iO>'-'"' 

C H AI R M A N L A R 3 0 N: W e 11 , p _• r h a p s a n y c o n t i n u i ri g 

discussion on this particular point that was raised? 

.No response._ 

MR. COHEN: There is one other issue that Mike's 

question brings up. What do we assume for the future? 

In the paper, we identify two alternative 

scenarios: one where we assume that soil-lead responds to 

changes in air-lead, instantaneously; and then the other 

where we maintain soil-lead over time. 

We feel that over the next few years, no matter 

what we do with the air-lead situation, the soil-lead is not 

going to respond substantially. We think a more plausible 

scenario is maintaining soi1-lead at whatever baseline levels 

we can define based on these empirical observations. 

When we talk about the case studies a little 

later, I think it will be a little more clear; but we are 

keeping soil-lead in the proposed approach at constant levels 

over the next few years. 

It may be much different to go out 20 years from 

now, but I think that is beyond our scope. 

DR. RABINOWITZ: So you don't use the derived 

regression line between soil-lead and air-lead in your 

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forecast ing. 

MR. COHEN: Not in the scenario that ..,t, are 

proposing as more plausible. We do use it to establish a 

baseline concent rat i or- of soil-lead. Otherwise, we will have 

nothing to put in for soil-lead concentrations. 

We think that these are reasonable relationships 

for the equilibrated concentrations. 

MR. MAINE?: What we think we are capturing in 

that, since we ars using studies for the related air-quality 

soil-lead level, recognizing prior years to one that study 

collected the air-quality data, that there may have been 

higher things. 

But that is representative of what is accumulated 

up to that point and tagged for a given study area. 

So it is an air-quality marker associated with 

that and we have varying soil-lead levels with varying airquality levels. 

CHAIRMAN LARSON: Do you see any air-lead 

reasonably constant, historically, at those sites? 

MR. COHEN: Yes. We tried to use studies that did 

not have major tumultuous smelter conditions. • You can't be 

sure of that in any way. 

We did exclude the bag house fires and things like 

that. 

DR. MARCUS: In fact, at the East Helena site for 

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one of the monitor location- there was essentially fivet six 

years- of continuous- data that made it very clear that 

condition- had been reasonably constant over the le?ngth of 

time that the lead uptake histories of the children being 

simulated were up to five, six years old. 

So t hat was a p ar t i c u 1 ar 1 ocation at whi i c h we 

definitely had reason to believe that we were doing an 

essentially stable or constant environment. 

MR. HAINES: I have one other observation on a 

concern expressed by Mike. 

You have fluctuating emissions around a smelter. 

It is a process source. A secondary smelter is the same 

thing. 

Quarterly being l-in-6-day data is not the 

greatest, but the mean value tends to reflect, to a degree, 

peaks. You can see day-to-day variation where you have 

higher peaks, but the mean will move up in relation to those 

peaks. 

So the quarterly average is not devoid of some 

representation of that. It may not capture the true 

magnitude of them, but it is reflected in the mean value. 

So I think using this historical air-quality data 

gives us a reasonable basis to assume a baseline going-in 

point. 

CHAIRMAN LARSON: What do you do about historical 

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ic'-ing these background values in 

' -''.i.e. 3 i i vi nq lead in urban areas 

lead data when yi-ou are pr 

the presence of f i. ••• _• y&io:-rfrom other sources'"1 

'Are those changes r_-f 1 ec:ted? 

MR. COHEN: We are? not going to make any changes 

to soil-lead as a result of that decline. The areas we are 

looking at.are directly adjacent to the point sources, and 

the- soil-lead there is dominated by the emissions from that 

fac i1i ty. 

The gasoline contributions seem to be relatively 

small. We think we are capturing it by using the empirLcal 

data, but we are not going to make any adjustment for the 

declines. 

DR. McLAMB: Well, to some extent we have. What 

we do in our forecasting methodology is we use the IFC short 

term dispersion model to figure out the points of interest 

where people are generally located, what the ambient 

concentration is from the source, and then we add on assumed 

background. 

To some extent, if that background reflects 

whatever residual lead is in gasoline, then it will be 

captures to that extent. 

DR. MAHAFFEY: I have another question about what 

the ambient measurements are. 

In some of the occupational literature, the 

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problems of Ontario in revising their acceptable OCCUJ:,:' '-.::;,,; 

standards analysed data where there was both d'ubi ent air 

sampling plus the dust that accumulated in various plants. 

They really came to the. conclusion that they 

real 1y .could not rely on just ambient sampling to reflect 

blood-lead even in occupational exposures. 

So in the kind of ambient sample you would have 

outside a plant, would you be missing much of the heavier 

particulate that might never really show up in your ambient 

sampling even with relatively high-volume samplers? 

I guess I question the extent to which the ambient 

sampling—which has certainly, in time, been a relatively 

short sample—reflects what may be coming out of the plant. 

CHAIRMAN LARSON: There must be some relationship 

here. 

From our discussion, I am picking up an 

interpretation that these are relatively steady air levels 

over time and reflect the soil values that, therefore, 

reflect some longer-term exposure. 

There are sort of steady-state points, if you 

will, on a graph. There is not necessarily some immediate 

relationship. 

DR. von LINDERN: I think, again, it depends on 

where you look in the soil column to some extent. When we 

look at that top inch of mineral soil, which is again below 

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the litter, we* don't see much change over 15 years. 

Over that 15-year period, we have had a 100-fold 

decrease in airborne levels. So that particular layer stays 

fairly constant, if you want to assume* a constant for that. 

What is immediately on the surface, though, is 

more of -a dust problem. 

MR. HAINES: One of the issues that we don't have 

an answer to, which I think is part of this problem, is: 

Whath is the accessible soil level? 

DR. von LINDERN: To children. 

MR. HAINES: To children. 

I think, unfortunately, we don't have a good 

answer. We don't know how to characterize that: whether or 

not they are getting the top 1 to 5 centimeters. That, I 

think, is going to vary with the situation in which they are 

piaced. 

If they are on a dirt play yard in an urban area 

and they are chewing up, you have to be concerned with much 

deeper soil depths. Other situations may not be very 

accessible for a very long period of time. 

In grassy areas, it works its way down. If you 

cut off emissions, they may not have ready access to it; but 

this is something nobody has looked at that I am aware of. 

We don't know how to address it. 

This is one reason, I think, we have concluded 

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•i estimatin g wl-.^.t t ho f 1 o n ci '•.. \ u d i. r, a 1 n a t u 

/hat happen- t h e -JJ.-J 

from both problems w: 

We don't have any dc.-i 

W i t h • r e d u c t i o n s i ; -, a: 

that are accessible? 

So I thinh: our preferred path is to try to assume? 

what the baseline is in the area the best we can using as 

robust a data set, using all available data. Use what, lock 

in here the soil-lead as a constant and vary, with air 

quality, what we call the dust-lead, which we describe as 

that being immediately deposited on the; surface, which we 

think should be fairly contemporaneous with air-qualitylevels. 

We feel this would be the most reasoned approach 

around this part's total data gaps we have. 

DR. von LINDERN: I think that is correct, 

certainly. 

The other complicater—and maybe we have one of 

the few sites where this becomes a serious complicater—is 

that soil below the source itself, in addition to air. 

MR. HAINES: Yes. 

DR. von LINDERN: It also gets into the pathway. 

So what you are seeing in the home as house dust and so on 

has come from that as well as from the airborne. 

MR. HAINES: This is from re-entrainment sources. 

Hopefully, this is where your air quality comes in. As that 

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dust is re-suspended to se^ti 4 . 1 i i.. e

_ I o :u : r 7 in the homes, it .... _.-'.; . . u be 

reflected on the monitors. 

DR. von LINDERN: There are- a couple of other 

pathways that at least we deal with. 

One is actually tracking that material into the 

home, and another one is pets in bringing that material in. 

This is never seen in the air-quality monitors. 

DR. McLAMB: We captured that as much as we could 

in the analysis we did on soil, air, and lead dust. In the 

household dust equation, we do have an unexplanable variable 

of soil which can, I believe, capture what you are referring 

to. 

MR. COHEN: Katie raised an issue—I don't know if 

anybody has any data; we might as well ask while we are 

here—on core-size particles that would not be collected by a 

high-volume instrument. 

MR. HAINES: This is basically for distribution of 

core particles. 

MR. HOFFNAGLE: The dust-fall-bucket data includes 

something larger than the high-volume sampler, but you cannot 

get a particular size on it. It is certainly not done 

routinely. 

MR. HAINES: The best way to come up with a 

response to the issue is to take an amount of lead and look 

at the distribution of particles, per se, and assume that 

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lea d ha s t o behav e -Gn-et;-

di sir i but i on s be e aus e we 

we sr e aware of. 

We coul d not i 

that issue . 

MR. HOFFNAGLE: 

'sg like that from these generalized 

• ;•"' t have it for lead-specific that 

rd any when we attempted to address 

There are distributions, of 

c o u r s e, i n t h s e ITS i s s i o n s, a n d t h e y are m e a s u r e d . 

MR. HAINES: Unfortunately, from the point of view 

of the principal sources now being futured in the storage 

piles, I think we even have sparse data there in size of 

that. 

As we look at the world today, the stacks if the 

controls are operating are reasonably wel1-controlled and 

probably are not having a significant where we are seeing the 

high blood levels in the children, which are quite close. 

All we have is a fugitive dust problem: either 

process fugitives coming off or handling, yard contamination 

being re-entrained. 

I am unaware that those particles have ever been 

sized. 

CHAIRMAN LARSON: That is a challenging and 

difficult problem, more difficult than it seems. 

DR. MAHAFFEY: Could we turn general for a bit? 

CHAIRMAN LARSON: That is fine. I was just going 

to suggest that we go to each individual member, perhaps 

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starting with you, to give us your gene;al impressions of Ihe 

report. 

DR. MAHAFFEY: A long time ago when we started 

some of this, one of the concerns had been talking about ai; -

lead/blood-lead ratios because while there is something that 

traditionally, perhaps, has been done, there were some major 

reasons for doing just that. 

Included in these reasons were the fact that it 

seems simplistic to look only at air with the realization 

that the lead and air winds up in the street, and this was 

back when the streets were containing 3,000 and 4,000 parts 

per million lead because of lead in gasoline. 

So the need to phase down lead in gasoline was 

recognized. No one needs to hear that history again. 

But we still are dealing with trying to look at 

air-lead and dust-lead. One of the questions that stands out 

to me in this modeling exercise—and this is not really to 

speak harshly of the model, but to really ask where is this 

going—is you have to question what kind of generalizations 

can be drawn from this model: Where can it be applied? 

We live near, not too near, a plant that has had 

some problem with uranium discharges. If you are talking 

about particulate airborne whatever, there is a temptation to 

use this model that it may well not apply very directly. 

I think maybe some of this has happened a bit over 

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time. When we started worrying about where the lead in airgoes and it winds up in the street, we were really, at that 

time, more concerned with c.n urban environment and how much 

lead was winding up in the street from gasoline esmi ssions. 

I am making some assumptions here, but one of the 

reasons you were-using the smelter-site information on the 

towns in Montane* is because they are characterized, because 

there tends to be data to look at these and an absence of 

data is one of the major problems throughout. 

The kind of discussion was had on which layer of 

the soil and dust reflects long-term lead emissions that have 

wound up in soil. Contrasting these with the current air 

level is one kind of correlation ratio regression, whatever 

kinds of, analysis you do with it in trying to estimate 

exposure. 

You are relating this back to an internal marker 

of those blood-leads that only in part reflect current 

exposures. There is one sentence back in here that even with 

the best situation in terms of environment measurement you 

could explain 30 percent of the variation in blood-lead. 

This tells you there is an awful lot missing. 

This is even with the best situation. 

So I think in may ways what has been done with the 

model is close to as good as we know how to do right now: 

that there is a serious absence of information to work with. 

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That is on- kind of problem. I want to • under s ::o; e 

the fact that I don't thirl-: this model •: j:.r, be broadly 

extrapolated in terms of other kinds of environmental 

problems of, if it is, here has to be real recognition •:., f 

what parts ot J; can and cannot be. 

That is a point I really want to emphasise. 

I think another problem is that while we ar& 

interested in biokinetics you cannot forget the biology, the 

physiology that undermines the biopart in biokinetic 

modeling. They are difficult issues. 

You ars attempting to use information that came 

from adult males in trying to extrapolate these kinds of 

pattersn of exposure and the distribution of lead within 

physiological systems to women, in particular pregnant women, 

and transfer of lead from the mother to the fetus. 

We know that the lead is transferred. There are 

case reports that talk about congenital lead poisoning. We 

know a little bit about this, but we really don't know very 

much about it except that it happens and that, given the 

longitudinal studies on neuro-behavioral effects of low-level 

lead exposure, low blood-leads are quite important. 

We don't have much experience with trying to model 

exposure in different body compartments of lead at these low 

exposures. There just is not much there to work with, except 

that we know that it is very important. 

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So again I think that this has to be emphasized in 

the di r.c ussi on. 

I don't want to really go on with the 

general i „at ions. I realize that you are trying to solve a 

spec i fi c p r ob1em. 

But I want to caution strongly against trying to 

extrapolate this model more broadly than I expect will 

happen. 

CHAIRMAN LARSON: Why don't we go around the table 

and let people share their general impressions of the docket, 

chapter by chapter, member by member, I guess. 

Would you like to start, Dr. Chisolm? 

DR. CHISOLM: Well, I think an overall comment is 

that given all the unknowns and all of the variability, you 

probably did as well as you could. 

I think one of the biggest variability ih all of 

this is the relative amount of soil that children will eat 

and whether or not we compare Dutch children. 

I am reminded of a quote from Rudyard Kipling to 

the effect that those who consider cleanliness second only to 

godliness have a damn low opinion of godliness. 

CLaughterl 

I think the Dutch might place it a little higher 

than many segments of our society. 

To me, that is the biggest uncertainty because it 

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i_ b_-h.~vio'. al . You are talking about biology, but it is a 

behavioral di f f er £-.,~r.- .;-,nong children. 

You really have.' to give fairly broad leeway to 

that, I think. 

CHAIRMAN LARSON: Do you feel that the numbers 

that were presented there capture the range of uncertainty? 

DR. CHISOLM: I am not sure about that. Suppose 

we see the stair-step children in town. You can get a wide 

range on blood-lead concentrations given the same general 

c i r c umstane es. 

You may say that it is the two-year-old who has 

the highest blood-lead, but that is not always true. I 

sometimes wonder about why I say the five-year-old might be 

much higher in the same circumstances. 

I can think of all sorts of things. Maybe her 

father was not the same as her husband, you know, and this 

kind is rejected. 

I am just saying that there are a lot of 

behavioral differences that make for other massive 

di fferences. 

I recall a child we had in the hospital no more 

than about six weeks ago with a blood-lead in, I think, the 

middle 60s and yet her siblings were not over about 20. They 

lived in the same circumstances. 

So there has to be something about that particular 

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individual. Often we see a broad range. 

I don't think it is common to see children livino 

in the same abode with blood-leads ranging from GO to "i'J, Tt 

is not unusual at all. 

I am talking about children in old houses. It i •-:-. 

the same general exposure for 'everybody. So I don't know 

that it really was contrary. 

In East Helena, those are fairly well-to-do 

people. They are not poor people, I don't think. There are 

a lot of socioeconomic differences. 

There are differences, I think, in the degree to 

which mothers of different ethnic backgrounds will tolerate.a 

lot of excess hand-to-mouth activity. So I think if you were 

to go do this study in, say, several sections of Boston you 

might come up with quite different answers. 

That would be a reason for not extrapolating what 

has been found in North Holland or what has been found in 

East Helena to the whole population. 

I would also say, try to grow some grass in the 

back yard where you have young children. 

CLaughter _ 

CHAIRMAN LARSON: That is a challenge. 

DR. CHISOLM: It is. 

So I think your comment about the surface soil 

being constant is well taken. 

s 

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MR. HAINE-: Do you 'want u„ to interject any 

o b s e r v a t i o n s ? 

CHAIRMAN LARSON: Any questions? 

MR. HAINES: Two points. 

Going back to the variation, we have two stages 

here. Is the model recognizing there is going to be a wide 

degree? Have we captured well enough that we can predict a 

mean recognizing that we are going to apply the GSD on top of 

that mean to try to capture the variability in it and the 

fact that the GSD derived from the East Helena work is 

similar to what is derived from NHANES? 

It is independently arrived at. It may be a 

perfect tool, but at least we are trying to interject in that 

variability what you are seeing. 

DR. CHISOLM: I just wonder if you have enough in 

it. 

MR. HAINES: Yes. 

I am not sure how to approach it other than what 

we are doing. We are trying to get at that problem through, 

really, a two-stage approach. 

On the uptake side, on the use of the Dutch data 

it is my understanding the way Jess applied that is basically 

use those children they looked at in the hospital itself in 

conjunction with Binder to derive the true baseline. 

Is that the best way to say it, Jeff: for a better 

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!;-..].

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base'"' • 

MR. COHEN: Pinoer, then • 

absorption of tiros;, elvmer.-;^, 

MR. HAINES: Yes. 

MR. COHEN: That is a big chunk of the picture. 

The only data that we had that we thought we could easily 

apply to that was the Clausen data: children who were not 

r o 11 i ng ar oun d i n t he d i r t . 

Until the data from the ongoing studies are 

available, I don't think we can really address that in any 

other way. . • 

I don't think it would be appropriate for us to 

use the dirt ingestion rates that Clausen found for those 

children. I agree there is probably a whole different set of 

behaviors between the two kinds of populations. 

We have tried to use the Binder study, but using 

the Dutch data to adjust for the unmeasured trace element 

absorption. 

DR. MARCUS: One more comment on the variation and 

the cultural factors. 

Some of the Cincinnati studies, published in 

§Qv_J_2D_)_-__iiiI Research about three years ago, actually showed 

how various subscales of the Caldwell Home Index 

quantitatively mediated theh dust-lead to hend-lead to bloodlead pathways. 

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We ar& vsry much aware of that. That is the 

reason, as was said, that only 30 percent of the variance is 

explained. 

' As far as these mouels are concerned, this is tht: 

reason why we belierve thc-?y are reflective of typical values 

in populations of children. I believe we are aware of the 

limitations in using them as a tool for predicting individual 

children's blood-leads. 

There are a lot of sources of variation. 

DR. CHISOLM: I was not putting it that way. 

DR. MARCUS: Okay. 

DR. CHISOLM: I was putting it more on different 

social strata and different ethnic groups that take quite a 

different attitude on it. 

DR. MARCUS: Yes, sometimes even in the same 

location if this were to be applied to populations about 

which one had relatively little such baseline information. 

MR. COHEN: There is one other point that Katie 

brought up on the lack of biokinetic data during pregnancy. 

We are left with estimating blood-leads for that 

population using air blood-lead slopes derived from male 

studies, basically. There is a real problem with that. 

We are not using any biokinetic adjustments for 

that. 

DR. MUSHAK: In 1985, we had a joint conference. 

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Marco Zarech discussed data from a .•ill age in Yugoslavia. 

Tiiey had a set of women who were studied, serial, 

for blood-lead. T believe their leads are available for that 

period, and probably dust-leads, also. 

So that is a group which can probably be probed in 

much closer detail. VQ_I might want to check with Graziano 

from Columbia. He; probably has all of that program. 

MR. TLAAK: There was high lead in part of it? 

DR. MUSHAK: Reasonably. 

DR. MAHAFFEY: They had a couple different groups, 

didn't they? They had different environmental locations" of 

blood-lead exposure? 

DR. MUSHAK: Right. 

This is a subgroup in which pregnancies were 

followed and they were serial. There were something like 7 

or 3 points each month of their pregnancies. 

DR. MARCUS: There is also the Manton isotope 

data. 

DR. MAHAFFEY: That is only on two or three 

people, though, right? 

DR. MUSHAK: Right. That's what we are left with. 

MR. HAINES: Five female subjects in the Dutch 

study, but that was for a very short exposure. 

DR. MAHAFFEY: As I recall that data, did their 

blood-leads go up faster or they had a greater response for a 

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given blood-lead? 

There were definite differences between the m„; ?.-

and fe?male subjects. 

DR. MARCUS: Yes. 

MR. HAINES: This raises a sort of provocative 

question from our point of view. 

We recognize the limitations of trying to estimate 

maternal blood-leads. Part of our dilemma is we have 

identified the fetus and are trying to trigger back. 

When we try to make use of the data, it may be so 

inappropriate that maybe we should not be attempting to .use 

these models to predict that relationship between adult 

females' maternal blood-leads. 

CHAIRMAN LARSON: That is the sense of what I am 

hearing. 

MR. HAINES: What I don't want to do is attempt to 

take what very limited data we have, try to apply it, and 

then say, "No, we should not be doing it." The better 

response may be that we cannot make those estimates at this 

point in time and we ought to focus on children for whom we 

can do a reasonable job of estimating exposures. 

DR. MUSHAK: I don't think anybody is saying that 

the pregnancy tail should be wagging the exposure-analysis 

dog. If you have the information, use it; but keep what you 

have. 

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MR. HAINES: Okay, according to the caveat of thelimit at ions of what we are doing. Okay. 

I just want to be clear on that. 

DR. MAHAFFEY: I reviewed a lot of the lead-inpregnancy information for something that we are doing at NIH. 

It is clear that while the cord blood-leads are 

very close to the maternal blood-leads, there are a lot of 

additional compartments. You have to take into account the 

amniotic fluid, the membranes the placenta. 

There are different components here that may not 

really agree that well with the maternal and the cord bloodlead. That part is not wel1-studied. What we know may be 

really based on lead poisoning pathology cases. 

So I think Paul's point is well taken: that you 

don't ignore the issue; but that the other side of this is to 

recognize, and be very up front about, that these are just 

basically best estimates in the absence of data for the group 

of concern, recognizing the Manton data that shows that bonelead does contribute and whatever you can obtain from the 

Yugoslavian experience. 

DR. MUSHAK: I think you might also add the 

paradoxical effect that you get in the Australian subset 

where you find that fetuses apparently are serving as a sink: 

that is, with higher lead exposures. You get lower bloodlead levels in women. 

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That is written up in Mike Davis--' paper. That is 

going to be a further problem: why you cannot use an end. 

CHAIRMAN LARSON: Okay. 

Ian, would you like to summarize. I know you have 

already shared with us some of your thoughts. 

DR. von LINDERN: We? have heard this before. I 

think it is a good job and I think it is as comprehensive as 

it can be. 

I spent the last year trying to do this for one 

site and it has driven me nuts. They are trying to do it for 

the world. :" 

CLaughter] 

I have a couple of things to share. I think Dr. 

Chisolm's comment is very appropriate. On our side, we have 

developed a risk profile for children who are typical and 

those who are what we call high risk, and they are the ones 

that we have to worry about. 

We have done the back calculations on ingestion 

rates. By the way, Region 10 released that document on 

Friday so you guys can have copies of it. 

At our site, it looks to us like 50 milligrams per 

day soil ingestion might be appropriate for the typical 

child, but when you look at the high-risk child, the child 

that we are concerned with protecting, it runs up in the 100 

area. 

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Region 10's position on that that they are 

offering out at this time is that we are going to use the 100 

milligram per day value. So there is a wide variation and it 

depends on' the very factors that Dr. Chisolm is talking 

about. 

Other comments: The air-lead to soils and dust 

thing does bother me. I think that is a very difficult one 

to do. 

As I said, the relationship of the smelter 

situation is as to what has gone on at that smelter over the 

last 30 years and not what we are measuring today. 

The other thing I note in the smelter that I need 

to explain a little better, that was in my comments, was not 

only is lead uptake related to the soil concentrations that 

we see in children's yards, but there seems to be another 

factor as well that, for us, seems to be explained by just 

the general level of contamination near the smelter. 

Maybe the other soils that children can get in 

contact with in addition to the ones specifically measured in 

their own yard and dust conditions in streets, and so on I 

think are important factors. 

Carol Engel, I think, noted that in her papers. 

The community exposure ended up being more important than the 

individual's yard exposure. 

The other point I have not heard much on—and I 

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don't know if this is the appropriate place, but I think we 

should say it—has to c'o with the monitoring frequency of the 

NWAOS. 

I think the one that is in place now for a 

situation like ours is almost totally inadequate. That is a 

measure once Bvery 6 days when we probably have about 11 days 

a year in which transport of material into the homes and dust 

storms is our critical variable. 

We don't measure that. 

I think it also should be looked at in terms of 

upsets and malfunctions in smelter situations. Region.S did 

an analysis back in 1984 at the Teflus Smelter which you 

might want to take a look at, in which I think it was 45 

percent of the total exposure over a three-month period was 

associated with one upset at the complex, which was actually 

tied back to 5 minutes of a fan being off. 

A short-term event can end up causing quite a bit 

of the exposure that we see in the community. Those are the 

types of exposures where larger particles get out and get in 

the house dust. 

My other point was I think as much as we wish to 

say that this is an air-quality situation, I know there is at 

least one person sitting at this table and several in the 

audience, I think, who are probably as concerned with how 

this is applied to soil clean-ups in the country. 

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I think we should all recognize that this can be 

used for that and some of the assumptions that we make should 

bear that in mind. 

CHAIRMAN LARSON: Do you think it is appropriate 

for that application: soil clean-up? 

DR. von LINDERN: Absolutely. I think it is the 

best that there is, but you have to make assumptions. 

CHAIRMAN LARSON: Right. 

DR. von LINDERN: You need to evaluate those 

assumptions in terms of what the ultimate remedy is going to 

be applied here. 

CHAIRMAN LARSON: John, did you have some 

questions? A comment? 

MR. HAINES: I would just make the observation 

that we are concerned about the monitoring issue. We will be 

addressing that in the staff paper both with regard to 

monitoring siting requirements and to the frequency of the 

sampling. 

Early next year, we will be laying that out in 

staff-paper form and, later, looking at needed revisions to 

th» air-quality surveillance requirements. 

MR. COHEN: I have one more comment. 

The fact that community exposure, not necessarily 

home-to-home yard-to-yard soi1-lead levels, may be more 

predictive or a better surrogate for integrated exposures, do 

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you think that would tend to support our use of the pooled 

data that we identified from all sorts of situations in the 

appendix there as opposed to the East Helena data set where 

the soil collections were done for each house? 

One of the other studies that they went out to is 

a park or a playground, for example. 

DR. von LINDERN: I don't necessarily believe that 

it is a better one. I think it is an additional one. 

I think that in the pathways it would reflect 

that: that children are exposed in their own home yard and 

house, and they also get out around the neighborhood and get 

into the other sources. 

So I think they both should be used. In fact, we 

have made an attempt to use both of them in the Region 10 

analysis. 

CHAIRMAN LARSON: Okay. 

Dr. Clark? 

DR. CLARK: Most models show that it is the uptake 

from the soils and the dust that get to the children. So 

seeing that once the lead is in the dust or soil, most of the 

model is the same regardless of how the lead got into the 

dust. 

I think some data on relationships from other 

studies can be useful in the model to extend the range of it. 

We have done that by applying our model to data from 

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7 h e y b v > t!'; a p p 1;: •• v e r y w ell. Y o u. get different 

slopes, but the model sti-l works: that the model from the 

lead and the surface and the soil into the dust in the home 

on the child's hands, the?;; blood-lead. 

So we pr obab1y cou1d use other data in here on 

that portion of the pathway because the lead from the soil 

could be from 30 years of activity of the mill or the mine, 

or it could be from 30 years or 100 years of paint 

deposition, automobile exhaust over the past several decades. 

There is some problem with differences in the 

availability of the lead in the different forms, but we think 

probably more data could be used in the modeling. 

I think there is a major impact on what is going 

to happen on soil-lead criteria for clean-up. I think that 

is the' ultimate area where we are going to have an impact 

because the exposures directly from the air are not that 

great now. 

It is the past air exposures where the health 

effects are occuring. 

DR. MUSHAK: What if you are doing a before and 

after? 

DR. CLARK: But it is what happened in the past, 

in terms of the air, where most of the health effects are 

occurring. It is residuals of former air-lead levels or lead 

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from other sources. 

We have a measure that we pre?fer on soil. It is a 

surface scraping. Some folks think it is just a horrible 

method scientifically, but it works. 

It is a scraping off a hard-packed surface or 

paved area. That is where the child has access now. 

It is now down 1 or 2 inches. That could be 

important in the long term, I agree; but the current exposure 

is what is on the surface. 

We have had a hard time convincing Rob Eli as to 

let us use that in addition to the soil. We are going,to.do 

our soil cores, the top couple—the top 2-1/2 centimeters, 

then 15 centimeters—but, also, we are going to use. a. surface 

scraping, which can be used both for hard-packed or any kind 

of soil because the child still is on the top and the top is 

where the higher levels are. 

DR. CHISOLM: From your point of view, "as I 

understand it, if you are thinking in terms of the long range 

and if you keep scraping it off and you are boring into a 

layer where it does not change for X sonometers, you would 

not be placing quite so much emphasis on just the surface 

scraping, I would not think. 

If you come back and scrape 10 years from now you 

would get the same thing, I think. 

MR. HAINES: This is part of the dilemma of 

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finding what is accessible. As that penetrates down, does it 

really, in fact, stay there? 

I think in situations it may stay in place. In a 

dirt school yard it probably will not stay in place because? 

t he? c h i 1 dr en will c ont i nual ly e hur n i t up again. 

The?, quote, accessibility problem that I think we 

are dealing with is what truly is accessible or not. 

DR. CHISOLM: You have to think longitudinally, I 

think. 

vary. 

DR. McLAMB: Yes, that is what I mean. It will 

CHAIRMAN LARSON: Allan? 

DR. MARCUS: On this accessibility, I think for 

perhaps risk assessment purposes a conservative approach 

regards the soil in the core, at least for a few centimeters, 

as accessible, a potential reservoir of lead that can be 

brought to the surface. 

A lot of people both in rural and urban areas keep 

big dogs. They dig holes, our children dig holes in the 

yard. People put in cable TV. 

There are a lot of things that would make soils in 

habitations accessible to a depth of at least a few 

centimeters. This is the reason why the most conservative 

approach would regard even those sub-surface reservoirs as 

potentially mobile. 

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DR. CHISOLM: As on e measurement , r i'.'m _l_ - total 

measurement. 

DR. MARCUS: It is ji'St one measure, and these 

have different purposes. 

If you are trying to look at current blood-leads, 

the immediately-accessible part is the part right there at 

the surface. If you are looking ahead towards how this or 

any other model would be used for clean-up, I think ycu would 

have to regard the potential accessibility of the sub-surface 

soiIs as wel1. 

As I suspect this or related models will be used 

for risk assessment purposes, those differences in purpose do 

have to be clarified. The generic relationships that were 

developed may need to be refined for particular purposes for 

other applications. 

As you say, we are looking for areas primarily 

around point sources where there has been an historically 

high deposition. Other purposes will probably require other 

refinements. 

That is all I can say. 

CHAIRMAN LARSON: I have a question". 

The other pathway which you mentioned as included 

in your model, on which I was not clear, was the soil-tohouse dust route. You had a term in your regression for 

soil, but that was a total soil sample rather than a surface 

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soil number. 

MR. COHEN: That was surface. 

The measurements were? derived from outdoor soil. 

DR. CLARK; One of the tables, I think, was street 

dirt and soi1. 

MR. COHEN: Yes. 

It is really surface-to-surface layers that may be 

1, 2, or 3 centimeters, not going any farther than that. 

CHAIRMAN LARSON: Is that the same surface that 

you were referring to? 

DR. CLARK: Well, not really. 

Actually, our surface is really what we can scrape 

off with a spatula on a hard pack. It is surprising: you can 

get a really quantitative measure there. You don't dig down 

in. 

Most soils where children are are not loose. You 

are not going to find many school playgrounds where it is 

like a garden. It just is not. 

The house dust is also a critical component. It 

can be tracked in by children or pets, be brought in by wind, 

whatever. It does not have to be that child, it can be an 

adult. 

But the pathway appears to be very clearly from 

the outside surface, inside surface, to the hand. Regardless 

of how it got on the outside surface, that is almost 

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irrelevant to the method, except for availability. 

CHAIRMAN LARSON: I am trying to get a sense as to 

what extent does a relatively rapid change in an air level 

r e f 1 e >:. t o n y o u r c o m p a r t m e n t s. 

DR. CLARK: Probably very little, depending upon. 

If we were doing this 30 years ago, it would be different; 

but not now. 

You would not measure it in most cases. In any 

urban area you would not measure it, I don't think because 

the reservoir is so tremendous. 

MR. HAINES: What we are really talking about is 

what is a reasonable approximation: Tim's question of how 

much of this is. laid-down, quote, soil-lead that may be 

tracked in by the pets and children; how much of it is 

interior dust related to contemporary deposition and, by 

"contemporary", at least during that period of time. 

I guess we are taking the approach, absent anybody 

partitioning that.out, apportioning it, that the dust 

measurement inside is fairly contemporaneously related to the 

air-quality level. 

So we feel that is a reasonable assumption that as 

you bring down air-lead levels that dust will move with it in 

a simultaneous fashion. 

DR. CLARK: We have seen, I think, some remarkable 

decreases in the past 3 or 10 years in our surface 

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measurements inside and outside? the home. There is a 

definite lowering that has to be associated with something in 

the air or outside. 

Now, it is going to tail off. It is tailing off 

now. It is harder to see any more changes. 

There is a 50 percent in almost all of our areas. 

whether it is in the public housing areas or in the older 

housing areas. So something is happening besides changes in 

the house. 

MR. COHEN: Are those data summarized? 

DR. CLARK: No, they are not. 

Well, they are in some reports. We don't have 

them published yet. 

MR. COHEN: Okay. 

DR. CLARK: We are seeing the decline in bloodleads and all of our other measures. 

MR. HAINES: Can we compare that to reductions in 

gasoline lead? 

DR. CLARK: You could, sure. It is paralleling 

the change in the lead additives usage. That is the past 7 

years or so. 

DR. CHISOLM: Are they tailing off toward the soil 

concentrations? 

DR. CLARK: Oh, they are leveling off. The 

decrease has been less in the past year or so. 

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••"•rr 

DR. von LINDERN: Art- any of those sites near 

these point sources? 

DR. CLARK: No. Maybe-.- some very small points, but 

r i o t hi r i g ma j or. We hav e some 1_ad ind ust r i es. 

A year and a half ago, we had a smal1 foundry with 

about 100 employees that had almost every worker with 

clinical lead poisoning. 

They were making poor man's peuter: the old 92 

percent lead peuter. One of the local industries decided 

this was a nice gift to give their employees and retirees at 

Christmas time. : " 

So the orders from this foundry increased 50-fold. 

They had no controls in the plant, no showers, and people 

carried enormous amounts of lead. People are still being 

affected by that. 

There are some adults who are actually going up in 

blood-lead after a year and a half, just a very major source. 

That was in a suburb. I didn't have much impact on the city 

itself. 

DR. MUSHAK: You are looking at the children, too? 

DR. CLARK: Nobody has concertedly because it is 

all over the place. 

DR. MUSHAK: They are a perfect target. 

DR. CLARK: The health department was looking at a 

few, doing some screening, and we have screened and tested 

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some outsider of the? city and done some? oi 

measurements. 

D R. M U S H A K: J u d g i n g f r o m t hi e 1 a c k o f o c c: u p a 1 1 o rial 

hygiene, I would say that the homes of these workers would be 

most affected. 

D R. C L A R K: 0 h , yes. T h e r e w e r e s o m _• c h i 1 cl r e n w h o 

were affected. One mother in particular, I know, 'wa_-

pregnant working at the foundry for the whole pregnancy. The 

child is in the SOs or 90s and has developed mental problems. 

This was a person living in a mobile home 50 miles 

in the country. 

CHAIRMAN LARSON: I have my Chairman's hat on here 

looking at the agenda. Maybe we can get the discussion 

started in full gear again after lunch. Perhaps you can hold 

your comments until them. 

If we break for lunch now and return at 1:30, that 

will give us an hour to complete our discussion here and then 

have a chance to hear about the case study applications. 

Okay. Thank you. 

CAt 12:30 p.m., the meeting recessed to reconvene 

at 2:04 p.m., this same day.] 

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AFTERNOON SESSION 

CHAIRMAN LARSON: Why don't we reconvene. I think 

we are moving along adequately still trying to stay on target 

for 4:00. We will pick up where we left off, with additional 

comments on the general document. 

Dr. Rabinowitz? 

DR. RABINOWITZ: My fortune cookie said that "If 

you eat dirt, you should eat clean dirt." 

[Laughter3 

The document is commendable. It is a difficult 

task and I think the authors did as well as they could with 

the gaps in the information. 

I guess that is it by way of general comment. 

Just having the discussion now is helpful to me to 

kind of see where this is going. That is one thing I missed 

in reading it through the first time: Why are we doing these 

different models, and what is the purpose of all this? 

I am sure the next draft will have that all taken 

care of. 

CHAIRMAN LARSON: I think we have an opportunity, 

perhaps, to get a final set of comments after we hear the 

later presentations this afternoon. I am sure you will have 

some other reactions to share after you hear those. 

Dr. Mushak? 

DR. MUSHAK: I thought the report and the whole 

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exercise was a coumendable job. I think that it also 

reflects the growth of sophistication in how the 

Environmental Protection Agency is going about its business. 

About 11 years ago, I sat down with a group of 

OAQPS types to take a look at articulating a startegy for an 

air-le.'ad standard. Basically I guess you can encapsulate the 

gist of it in about two paragraphs: forget page after page of 

rigmaroles, just the essence of it was two paragraphs. 

Have something on frequency distribution, look at 

something about everything except air and get a PBA letter of 

about 2 and you get 1.5. 

We have come a long way since then. The report 

has probably taken the parameters as far as we can go with 

them, but I think we ought not to bash the uncertainty 

because I think that it has been said by public health types 

all the time that there is compelling evidence and then there 

is irrefutable evidence. 

That is, once evidence is compelling we ought not 

to insist that it be irrefutable from a public health 

protection stance. 

This is a stance which I think the Environmental 

Protection Agency is, both legally and morally, mandated to 

practice. 

Also, I think needs are both compelling and 

irrefutable. I think that a model like this is a compelling 

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need. 

About the popularity of the model for other 

application — i.e., a global or generic uptake b 1. o '••: :•. n e I .i. c 

model--! would see some utility in, say, these various .. 1«_._nups. I think the clean-ups are a good way to test the irod^I 

because apparently in Julian's case in Boston, and in 

Cincinnati, pre- and post-blood-leads ers being collect...'. 

Is that correct? 

DR. CHISOLM: That's correct. 

DR. MUSHAK: So you could validate the model's 

application with pre- and post-blood-leads to see how the. 

prediction worked. 

I would also caution that if one is to use a model 

for soil lead—Jeff Cohen and I spoke about this briefly 

before—if you do something like a rather broad traversal 

down a soil-lead/blood-lead slope you may be jumping from a 

non-linear part of that model's dominance to a linear. 

You might want to be careful. 

As I remember Ian's curves with the competence 

limits between blood-lead and soil-lead, you get extreme 

curvalinearity above, say, about 4,000 ppm. In other words, 

PPBs become quite curvalinear above about 4,000 ppm of soil. 

So one has to be careful what range of that 

hypothetical model curve you are speaking of. 

I think it is probably a good model for lead in 

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certain other contexts. I don't think it's generic model for 

fill-in blank A metal and then you can do it because lead, 

u n f o r t u r. a t e 1 y, i s 11 \ e o n 1 y m o d e 1 that is studied well e n o u. g h 

that I think you can do a model and base this on. 

Other applications of the model? I guess we 

talked briefly over lunch about the prospect of pregnantwomen at term: look at newborn blood-lead modeling, some 

hybrid of Mike's early modeling plus the KNIPE variation. 

That is something to consider. 

Or you could stick with the disaggregate model as 

you are doing now, but I think there is some virtue in-trying 

to model newborn bloods. You get at least one more 

developmental point. 

I think that in-utero exposure modeling is 

probably lost to you until there are some breakthroughs in 

non-hazardous in-vivo modeling of soft tissues. I don't see 

how that could work. 

The uncertainties have been considered. I think 

that 100 milligrams of dust/soil combined intake is certainly 

righteous. I don't think that numbers below this are really 

appropriate. 

There is much scatter in the dust and soil 

average, but I think 100 is — 

CHAIRMAN LARSON: As a mean value? 

DR. MUSHAK: As a mean value, understanding that 

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there i =_ a fair amount cf scat •__.-.• ...round it. 

WP h.ve to realise that around this m__an thei e are 

dusk intakes, soil intakes which can be quite huge. 

I recall that there were some studies based on 

mineral trace elements that had gotten levels above a gram. 

Whether or not those are out Iyer type levels because of 

problems, I am not sure. 

I would say if you look at the evidence in the 

aggregate, 100 is not too bad a number. 

That is it on that. 

CHAIRMAN LARSON: Bob? 

DR. ROWE: I don't really have a lot more to say 

in terms of all the comments that have been written and said 

here in terms of conducting a rural point-source-oriented 

NAAQS exposure assessment. 

It seems like that will be fine. My only comment 

is that in the ideal of ideal worlds it would sure be nice to 

know what even a small change in air would do in the urban 

areas because we would probably ultimately have more people 

affected. 

It may not be the most cost-effective strategy, 

but that would be nice. We are going to have just small 

people here compared to the urban-area problem, but that has 

been a previously-agreed-to decision and I don't have any 

problem with that decision. 

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So, no, I think we are on track. 

CHAIRMAN LARSON: I !• i a v e a c o u p 1 e c o m m e r 11 s m y s e 1 f. 

Just from somebody viewing this model from afar, 

it would be nice to see the predictions from the f.icility 

t I-i at you are concerned with of the concentrations of those 

environmental variables that are important in the ultimate 

determination of blood-lead. 

Specifically if you have an observed gradient 

within a few miles of a point source, can you also predict 

with your model the RUN C type of thinking, the air-lead and 

dust-lead now values that you see in the mean, perhaps,•that 

you are using ultimately in the prediction. 

The reason I say that is because it becomes easier 

for the not-so-familiar reader to distinguish between your 

model's ability to predict uptake versus exposure. You could 

potentially be right for the wrong reasons. 

I don't think you are, but it would be nice to 

have some of those intermediate mean values or median values 

in there as well. I think we heard some of that this morning 

in terms of those particular issues. 

That is one general comment. 

I agree, though, that you have come a long way in 

this particular process and that the observation of a 

gradient blood-lead, even in a limited area, and the ability 

to forecast it with some, at least, gradient or relative 

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gradient is an impressive ability. 

What I am hearing is that we are only talking here 

about forecasting mean values. I get some sense that if we 

played around with soil-lead averages or whatever, we may or 

may not be as good in agreement with these case studies as 

y o u .. _-:• e i n t h i s p a r t i c u 1 a r re p o r t. 

But, still, some notion—and I don't know how you 

do it-—of whether or not your predicted versus your observed 

mean values at different points away from the source are 

different from each other. 

I don't have a good feeling for how to appro.ach 

that since you have an range of uncertainties and not a lot 

of information on the shape of the points in between and the 

range, but it would be nice to make an attempt to see, even 

if the model and the predicted observed lead gradients are 

not quite the same, that there is some overlap there given 

all the uncertainties. 

Just sort of stepping back, it would be nice to 

see the intermediate prediction of, now, I guess we are 

talking dust-lead and air-lead in the mean, and then the 

resulting forecasts for blood-lead and their uncertainties 

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compared to the mean observed values, which takes us to the 

next point. 

Given some ability to predict that mean gradient, 

is it reasonable to take the next step, which is then to take 

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that mean, or mean prediction, from the model and apply ,. 

geometric standard deviation as is proposed here _ n terns :..f 

forecasting the number of children, in this case, that are ._; -; 

excess of X blood? 

I would be interested in hearing other Commit.ee 

members' reactions to that particular approach to this 

variability issue. We have heard a lot about all the 

potential sources of variability in the actual data. 

DR. MAHAFFEY: I think what is puss ling to me is a 

concern about whether or not these geometric standard 

deviations would apply at extremely low blood-leads, tal-king 

perhaps blood-leads under 10. 

There is a little bit of information suggesting 

that you have a different slope in the relationship between 

environmental lead exposure and indicators of blood-lead, and 

that that slope will differ depending on the level of 

exposure. 

So whether or not you have that same standard 

geometric deviation across a wide range I think is 

questionable. 

That is just an opinion. 

CHAIRMAN LARSON: Would you expect it to be harder 

to characterise what the variability is? Is it that given 

the perfect ability to characterise it you would expect it to 

be different in terms of measurement, just approaching 

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1 measurement limits? 

2 I don't expect an answer. I just throw that out. 

3 It is striking to me. I .on't know enough about 

4 the NHANES data set, but I am reading in here that across the 

5 whole spectrum of blood-lead levels in that survey things 

6 seem to be log-normally distributed with a reasonably 

7 constant geometrically standard deviation. 

8 DR. MAHAFFEY: We did not have such low leads in 

9 that. 

10 CHAIRMAN LARSON: That is right. 

11 DR. MUSHAK: That is a key point: that the low end 

12 of the table by 1390 in the rural case adds maybe .25 or .5 . 

13 per cubic meter. You would still be looking at something. 

14 I think the analytical varying problem remains 

15 severe. Okay. There is no reason to expect that good leads 

16 would perform any better than they can; they already are. 

17 And I don't think that poor leads are going to get religion 

18 any time soon. 

19 You have the analytical factor that is driven by 

20 that particular configuration. 

21 I think there is something about the 

22 pharmacokinetics of lead that may compel a log-normal 

23 distribution with a lingering tail upwards. You see this, 

24 for example. 

25 You look at food stuffs, anything that has a 

_ 

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biologically—interactive :i nt e> 'lace., and it has a 1 og—r.ordial 

distribution. The concerv. r ...t ! ons av_, 3. i !•-..:-, parts per 

bi11ion. 

When you look at sit, what kind of distribution 

would you se. in ai<? 

CHAIRMAN LAF'30!'-.'L It is log-normal, for the most 

part. The variance is in proportion to the mean level. 

DR. MUSHAK: I mean at the level we are talking 

about, .1, .2. 

CHAIRMAN LARSON: I think at any level. I think 

you can slice it up how you want and it comes out to be.lognormal, perhaps for a different set of reasons. 

MR. HAINES: It could be. 

CHAIRMAN LARSON: I would expect if you have a 

log-normal distribution that you would expect the absolute 

variance to shrink as the mean goes down in a proportional 

way. 

It is hard to think in log terms. I guess we can 

see in log terms. 

DR. MARCUS: Actually, I think that is it. The 

variability in absolute terms does get smaller as the levels 

get smaller, but in relative terms for a lot of different 

populations over a very wide range of mean levels of bloodlead. 

If you don't like talking about geometric standard 

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deviations, you can convert it into a coefficient of 

variation, which is a ratio of a standard deviation to a 

mean. It is a familiar percentage measure of variability for 

blood—leads where you have a variety of sources, no one of 

which is really overwhelming. 

Thi5 is the situation we are looking at more and 

more in urban and rural areas where lead in diet contributes 

something and water-lead contributes something and then the 

ambient air, dust and soil levels also contribute their bit 

so none of them is totally dominant. 

If you have several contributions to blood-lead, 

then you would be running into variations from one individual 

to another even with almost exactly the same exposure, almost 

the same location: be running into typical variations in 

blood-lead which would be plus or minus 40 percent for GSTs 

of 1.42 scaled back, 

35, 40 percent would be a typical kind of 

proportionate variability. This is because there is a 

diversity of sources. 

You have biological variability. People differ in 

the amount that they can absorb through the duct, through 

the lungs, where they have a higher ventilation rate. There 

are lots of differences from one individual to another, 

biological differences, then differences in exposure. 

Some people eat more dirt than other people and 

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all these contribute tc- that variability. 

So a typical measure of variability seems to be 

reasonably proportional to the mean even down to fairly low 

levels. 

There is something that does not seem to shrink at 

low levels. As mentioned, that is the analytical 

vari abi1..1 y. 

You cannot knock that down lower than a couple of 

micrograms per deciliter. 

CHAIRMAN LARSON: That is a constant on top of 

things that are continually shrinking. • 

DR. MARCUS: There have not been any efforts made 

in this incident to correct these GSDs for the variations in 

the analytical variability because any standards that are set 

are going to have to take the fact that this is a built-in 

measurement. 

Compliance tests have that analytical variability 

built in. So we did not make any adjustments for analytical 

variability in these calculations. 

DR. MUSHAK: But the early NHANES analyses did. 

MR. COHEN: Yes. I guess the decision was not to 

take that into account because of all the health studies they 

were going to be relating to. 

CHAIRMAN LARSON: If we are uncertain, 

collectively or individually, about what the geometric 

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standard deviations would do around these site- in . a.icv_r.y 

the source, is there any sense of if they would be ip'eaie. or 

less t \. a n they currently a r <•_ ? 

'Or can we not ±.&y that? 

DR. RABINOWITZ: We could just venture a guess. 

I get the sense that contained within this lognormal distribution of blood-leads that we see ar& reallymany sub-populations. Even if you plot them all together and 

add them up, it all looks like some log-normal straight line. 

There are really many different populations. By 

changing exposure to, say, airborne lead and leaving these 

other factors constant, many people will decrease their lead 

levels and blood-leads. Everybody will take a step to the 

left, as it were. 

But many people, some sub-populations, are still 

getting lead from some other non-air source. These people 

will not track where the others track. 

You are going to see a broadening of the 

distribution. The magnitude of that broadening? Gee, I 

don't know, but it would be surprised if everybody uniformly 

kept the same variance and decreased the mean. 

Is it possible to think in terms of keeping the 

variance as large as it is and just decreasing the mean as 

one extreme set of possibilities? Then you wind up with 

having some tail, some high-exposure tail which, even though 

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you have sero lead in the air, .you ars still going to h..v_ 

these children getting lead from other sources. 

DR. MUSHAK: But t hen we ar e g e11 i ng b ac k t o t h i s 

paint and non-paint, arid rural. We went through that once 

before. 

Presumably you are going to be fairly well rid of 

paint exposures, or even the idiosyncratic exposure, cultural 

exposure. 

So that should be minimum. 

DR. MARCUS: These are all plausible ways of 

dealing with it, but short of actually looking at a situation 

in which there is going to be a substantial change in 

exposure and looking at children before and after, and 

tracking which ones had their blood-leads drop a lot and 

which ones did not have their blood-leads drops so much 

because they were not getting it from that kind of exposure 

anyway. 

Short of actually doing these studies where you do 

manipulate the lead exposure in the environment, I don't; 

think we have, quote, the right, end quote, answer to this. 

So the attempt, at least, to estimate the fraction 

of high-lead children by assuming a constant proportional 

variability seemed like a reasonable approach. We are 

certainly agreeable to looking at other alternatives that are 

suggested. 

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CHAIRMAN !. ARSON: Semant 5 c sl 1 y, don't we really 

have two different ft,ode-Is, though, here? We have an uptake 

biokinetic model which predicts the means, and then we have 

another model which predicts the variability within the 

population that should not be confused with the uptake 

b i oki net i c model. 

So we could make that distinction. I think it 

would be useful, at least, for people to know that they are 

really two different models coming from two different places. 

MR. COHEN: There was one data set, the NHANES II, 

where we did have the opportunity to play with the shape of 

the distribution. Joel Schwartz looked at different cut-offs 

and moved children down, moving down the mean associated with 

that from 40, let's say, or 30 micrograms per deciliter. 

In other words, he would take all the children 

above 40 and move them down somewhere else. 

We found that the GSD really did not change 

significantly when he did that. 

DR. RABINOWITZ: How did he move them down? You 

mean down by selecting sub-groups with lower exposure? 

MR. COHEN: He took the sub-groups with higher 

exposure and tailed them. It really boiled down to the fact 

there just were not that many children up there; but if you 

use 40 as a cut-off, I think the GSD changed from 1.43 to 

1.42. 

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DR. RABINOWITZ; Very small difference. 

MR. COHEN: Yes. 

I think we talked about doing that kind of thing 

with the East Helena data to see what effect it would have on 

the overall GSD, anticipating that a lot of these children 

would have lower exposures in the future. 

We have not done that, but we could. 

DR. RABINOWITZ: Are you satisfied with the 

biokinetic modeling that the variability that you see with 

all these different terms finds its way into the end of the 

model? ... 

This model is used to generate distribution at the 

end and it is based on certain of these variables. Each of 

these variables has uncertainties associated with it. 

When you put them all together in the model, all 

these uncertainties should add or compound in some way. I 

don't know if you feel that that is being taken into account. 

DR. MARCUS: What you could do in the extremely 

ideal universe is take all these 20 or so input parameters, 

convene a panel of experts to tell you what the distribution 

of parameters is in the biological or exposure population, 

and do humongous simulation with a distribution of every one 

of those parameters. 

This would give you some way of propogating the 

uncertainties through the model. This is not a feasible 

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program right at the moment, I think. 

We have done sensitivity analyses with a couple of 

the parameters that were, a priori, thought to be the most 

sensitive, including the absorption rates, which had actually 

some empirical support. We are going to look at the East 

HeI en a. 

But short of a systematic exploration of the 

sensitivity of the model to plausible distributions over all 

those inputs, in many cases we would be dealing with an 

almost non-existent empirical data base to do that. 

Yes, I would like to be able to do that and then 

say, "If you propogate all these uncertainties through, here 

is the real uncertainty"; but it looks like a lot of work 

right now. 

I suspect we would end up creating a version of 

the central limit there which says that if you add up a bunch 

of things, it turns out to be about normally distributed. 

Here we are going- to end up with sort of multiplicative 

factors because uncertainty in absorption rate multiplies to 

uncertainty in the amount of dirt that is eaten which 

multiplies into something else and you will end up with a 

log-normal distribution, pretty near, because of the large 

number of things that multiply each other. 

Yes, it is possible; but I don't think that we are 

going to have grossly different results even if we could 

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carry out that program and if we knew.what kinds of 

uncertainties in some :••' these input parameters we would be 

dealing with. 

'DR. RABINOWITZ: My concern, maybe echoing Dr. 

Marcus said, was that when you ar(.i all done you don't want to 

have too much faith that your answer is finally right', that 

somehow you have to have, ail the caveats and the 

uncertainties in the final results. 

I don't know how you do that carefully. 

DR. MARCUS: I think our concern is particular 

with those who are most highly at risk; and that we are-not 

going to be greatly underestimating the high-risk subpopulation. 

That is why we are tending towards the use of a 

larger GSD than in some studies. 

DR. MUSHAK: Yes. 

MR. HAINES: The other point I wanted to make is 

our purpose of the model is to look at relative differences 

between alternative strategies eventually. I am trying to 

say we could be off in the absolute number, but if we show 

ths deltas between standard A and standard B, even though we 

may be low in both cases or too high in both cases, it is the 

relative additional protection one alternative has over 

another that is what we are seeking. 

I feel that the model behaves itself reasonably 

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well. W e ma y b e r, o t q u i t e f i n d i n g p r o of in o u. r p r e d i c t i v e 

power, but if we can get a reasonable benchmark snd help the 

deci si or.-maker decide between two alternatives, we may be 

somewhere. 

DR. RABINOWITZ: As long as people don't, then, 

use it for something else, it will be all right. That is a 

hazard. 

MR. HAINES: We will worry about mis-application 

of models later. 

[Laughter] 

DR. von LINDERN: I can tell you what our 

experience has been back in the days when it really used to 

rain lead in our community and our blood-lead levels were 20, 

30, 40, SO, 100 and above. 

We saw that standard deviation collapse somewhere 

down toward 1.3. I think that is probably reflective of a 

biological and analytical variance. 

Nowadays we see it pushed beyond 1.42 and it is up 

about 1.5 now. I think that is because we are dealing with 

more than one pathway or exposure route. 

When you have two or three exposure routes that 

are competing, that adds to that variance. 

I would expect, as we get toward lower blood-lead 

levels when different routes can have more equal influence, 

you are going to have to go to a larger number. 

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*•:.'.:•••/. rrjr y T i i i •: o c ar r y !..!•-• i s guess, si n::. e we 

are guessing, slightly 'ai i'ler, when y:.u are going to 

pathways where there is not such a cI ear domination of one 

over another, you may have some real differences in the bioavailability of the different sources. 

Seme of what we see as a fairly increase in intake 

of blood —lead-- I am thinking of .he studies with the infants 

where there was water used for making infant formula and it 

looked like there? was a fairly rapid increase in blood-lead — 

that may be age, it may be a difference in previous body 

stories of lead. It could be a lot of things. 

It could be bio-availability. 

I think with blood-leads other circumstances 

applying standard deviations obtained from other data sets is 

something that is chancy to do. In a way it is supporting 

what Ian and Mike have been saying. 

I am not sure I am expressing it clearly. 

CHAIRMAN LARSON: Would you be more comfortable 

with a range of GSDs? 

If you leave them without the option of Model 2, 

which is this GSD application to the mean, then they are back 

to square zero in terms of predicting the levels of those 

children. 

DR. von LINDERN: I think it is the way to do it. 

When you see our document, you will see we did it that way, 

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too. 

-Laughter] 

DR. RABINOWITZ: Which was are you referring to 

now':-' 

DR. von LINDERN: It is, but I am sure everyone 

here is aware that that becomes a very, very sensitive 

parameter, though, when you are talking about the percentage 

of children that exceed the blood-lead level and we are 

talking about protecting in the 2, 3, 5 percent level or 

whatever they select. 

The.t is an important value. I think we shoul.d 

recognise that. 

DR. MARCUS: Maybe I should address this to the 

Committee as a whole. 

Would you, then, to compare the sensitivity of 

these estimates to a population with more variability to see 

whether or not that makes a difference? 

DR. von LINDERN: Certainly. I think probably the 

way to express that is in percent exceedances, where we end 

up. 

DR. MARCUS: Okay. 

DR. von LINDERN: The question is what are the 

blood-lead values; but that is not here to be decided. 

CHAIRMAN LARSON: I guess we are saying that that 

is an important parameter. It should not be defended, if you 

> . 

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will , f r om th e pu r e 1 y up t ak e b i o k i ne t i c app r oa.h . 

I t coul d b e defended , bu t i t i s obviousl y a -rsry 

sensitiv e paramete r i n th e whol e result . 

A r e ther e an y othe r comment s fro m th e Conin.itte e 

members'" 

r 1.1 .. ... ... ... __ . _ -i 

_r.o f tipoii.- , J 

We can now hear from you fellow about the case 

st udi es. 

MR. COHEN: Okay. 

Before we leave this, before the break Ian talked 

about typical soil ingestion rates that they derived in 

Bunker Hill. 

I guess one thing that we should note in that 

population is there was a long history of severe lead 

poisoning problems. There was a lot of publicity and a very 

aggressive intervention program that may have resulted in a 

higher consciousness about sanitaryn habits on the part of 

parents. 

I tend to not use the typical Bunker Hill child as 

compared to the quote/unquote high-risk case for 

extrapolating from the model to the places and not presume 

that these other places would have the same kinds of 

education or public health awareness. 

CHAIRMAN LARSON: Is this getting back to the 

issue of how many milligrams of dirt we eat per day? 

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MR. COHEN: Right . 

CHAIRMAN LARSON: It seems 

few numbers getting passed around. 

DP. MUSHAK: This business of education _\r.d 

parental apprehension in driving down tliat numbe 

know of a case—it has not been written up in any formal 

way—in eastern Pennsylvania where after there had been a lot 

of community publicity the parents literally chased the 

children into their own houses. 

It was that kind of culture to begin with: bluecollar, very stringent attention on kids. Those kids were 

literally harassed. 

Some of the psychological problems may be worse 

than the problem. 

[Laughter 3 

The fact remaining is I think once you have a 

pervasive community awareness, parentally, of the. problems in 

that issue you are going to turn up with less and less of a 

problem. We can see it anecdotally in the Bunker Hill 

situation. 

So it may not be appropriate. In other words, the 

ideal case is if there were no awareness and everybody was 

doing the same old thing, what would be the average? 

DR. von LINDERN: For those who want to punish 

yourselves, this is the report. It was just sent out Friday. 

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I am sure there are copies available for 

to review it. 

It is a proposal and it is subject to change based 

on all the comments that come in over the next month; but, on 

Jeff's point, the position that has been laid out at this 

time is that we expect those values are depressed as a result 

of years of attention being paid to this problem up there. 

I think that is particularly true with the typical 

child, perhaps not so true with the high-risk child. Maybe 

one of the reasons why it is a high-risk child is because it 

has not worked with the high-risk child. 

So the recommendation at this point is to use 100 

milligrams per day to represent a two-year-old, and it is 

based on the recommendation of— I cannot remember out of 

which office of Environmental Protection Agency it came—a 

symposium on soil ingestion rates. 

DR. MARCUS: I believe that was the Exposure 

Assessment Group. I am not real sure. 

DR. von LINDERN: At this point, we think the 100 

milligrams per day is appropriate. We don't see any reason, 

at least in our data, to use any other number. 

CHAIRMAN LARSON: And you apply a GSD on that mean 

prediction? 

MR. COHEN: Around that, that's right: around the 

end result. 

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CHAIRMAN LARS0N: I am somewhat c on f used by t he 

notion of a high-risk person versus the average person. 

DR. von LINDERN: I hope I anticipate this answer. 

Yo1.1. carinot thi nk of a hi gh-r i sk child in the 

Bunker Hill situation in terms of pi us-two standard 

deviations, that type of thing. There is a fairly 

substantial percentage of our children who are at high risk 

because they are living in an environment at a high 

concentration. 

That does not apply that, statistically, it is a 

plus or minus standard two deviation type of thing. It.is a 

profile that we use. 

I don't know what the exact percentage is, but it 

is quite a bit higher than that. 

CHAIRMAN LARSON: Would that type of information 

be available for these other places where you are planning to 

this extrapolation sort of thing? 

MR. COHEN: Not that I know of. 

MR. HAINES: East Helena is probably the onlyother data set. 

MR. COHEN: And East Helena was the study location 

for the Binder and all study action, the source of our 

estimate. 

DR. RABINOWITZ: Are you in touch with Chuck 

Gilbert? 

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1 MR. COHEN: Yes. 

2 DR. RABINOWITZ: He had numbers. 

3 MR. COHEN: I have not talked to him in three 

4 months, but I have been keeping in touch with Paul White who 

5 is also doing a similar study out in Washington State. We 

6 are anticipating those results. 

7 Hopefully we will be able to incorporate those 

8 into our final set of parameters. 

9 CHAIRMAN LARSON: Okay, Jeff. 

10 MR. COHEN: In our handouts, it is the second 

11 table. 

12 DR. von LINDERN: I have that reference if you are 

13 interested in it: £2____oguiem 2J_ Oil i-Q__ ___._--_-_I _f__E2-l--____' £.2 

14 _-2i__ __Q__ D___-__JL Ei_____-A_2_-_?<5-2_D_§Q__ Form. That was ORD, March. 

15 MR. COHEN: March 1988? 

16 CASE STUDY RESULTS AND DISCUSSION 

17 MR. COHEN: I am going to show you some 

18 preliminary results actually running this model, where we 

19 have been debating about this model. These are in 

20 populations of children living near East Helena and a 

21 secondary population in Dallas. 

22 We looked at various alternative scenarios, 

23 including a quarterly average standard, which is equivalent 

24 to the current level, 1.5, and then five alternative monthly 

25 average standards between .5 and 1.5. 

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We also estimated •_ h i. 1 d r en " s b 1 ood -1 ead w i t h t h e 

aggregate model and adults' using the disaggregate approach, 

as described in the report. This is obviously taken up in 

the recommendations we have been hearing today. 

Again, we have assumed two alternative soil-lead 

scenarios: one where soil-lead is maintained at baseline 

levels regardless of what air-lead changes occurred after 

1990; and the other alternative is assuming that, for 

whatever reason, soil-lead does respond instantaneously. 

We were uncertain what the right call is there. 

We just wanted to balance what might be plausible. 

DR. RABINOWITZ: Baseline. You don't mean 

background. 

MR. COHEN: Baseline air quality as it exists 

today. 

DR. RABINOWITZ: Okay. 

MR. COHEN: This is Scenario 2, which we feel is 

the more plausible scenario, keeping soil at constant over 

the new few years. Dallas and East Helena are listed: 241 

children in Dallas, 217 in East Helena. 

Mean blood-leads are shown for the-different 

scenarios and using the GSD of 1.42 we calculated percentages 

above selected blood-leads. They are just shown as examples. 

The 25 is, I think, still currently CBC's 

definition of toxicity. It probably will change in the near 

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DR. MARCUS: The betting is it will drop. 

MR. COHEN: Right. 

DR. von LINDERN: What is your soil assumption 

there? 

MR. COHEN: The soil assumption is that it is set 

at whatever air quality is in 1990, except for the baseline 

case. In other words, air-lead has been fairly constant over 

the previous years and the soil-lead is estimated based on 

that air quality. 

After the new standard.is set, it remains fiyed. 

DR. von LINDERN: So it came from that formula you 

discussed before? 

MR. COHEN: Yes. That is an equilibrated soil, 

and based on that progression model. 

Just to read across the top line to give you an 

idea of what is going on, for the 1988 baseline in Dallas we 

have a mean blood-lead of 7.5. 20 percent or so of the 

children would be about 10 and 2.3 percent would be about 15 

and .03 above 25. 

DR. MUSHAK: That is for certain air-leads and 

certian soil-leads. 

MR. COHEN: Yes. It is actually a certain airlead standard and the associated air-quality impacts around 

the source given that standard. 

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DR. von LINDERN: Do you know what that number is 

of the lead equilibrated? 

MR. COHEN: We estimate air quality at the highest 

receptor point, dust at that standard, whatever standard that 

we are looking at. 

DR. von LINDERN: So when we are looking at 1.5, 

we are saying 1.5 is the maximum receptor point. 

MR. COHEN: Then the air quality would be 

dispersed in the model around that. Soil-lead would be 

predicted for each receptor point and spread out on a block— 

by-block basis in this case based on the regression model, of 

the equilibrated soil air-lead relationships. 

I don't have it here, but I was going to show you 

the results that we got from the aggregate model for 

children. That is where we use the air/blood/soil-level 

slope similar to what was done in 1978. 

I think it is in the hand-out. It is a plot of 

the results looking at only percentages above 10 micrograms 

per decimeter. You can see the sensitivity of the results 

and see what soil scenario you look at. 

Scenario 1, again, is assuming that air-lead 

produces an instantaneous change in soil-lead levels. You 

can also see that there are some differences between 

locations: Dallas, in one scenario having lower blood-leads; 

in the other slightly higher for the lower standards. 

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are lisJed ov^r there. I think I do have a plot of the 

results for the aggregate model, obviously on one scenario 

just loo I: ing at the ai. r-1 ead/b 1 ood-1 e. ad relationship directly 

without going through soil-lead assumptions. 

DR. von LINDERN: There is a difference in that 

because of the geographic lay-out of the area? 

MR. COHEN: Yes, and because of the air-quality 

impacts. 

DR. von LINDERN: The modeling impacts where the 

receptors are? 

DR. McLAMB: And the distribution of people. 

MR. HAINES: How close they are to the site. 

DR. McLAMB: Exactly. Are they coincident with 

the high receptor values for the modeling exercise? 

MR. COHEN: We have done the same kinds of things 

for middle-age men, in this case whites, using the 

disaggregate model. Again, you could see the mean bloodleads, percentages above various selected cut-offs. 

In this case, we went down to 8, 10 at 15. In 

Dallas, for example, we predict 18-1/2 percent would be above 

8, 5.4 percent would be above 10 in 1988 baseline. 

From what we heard today, I think we need to reexamine the methodology we use to estimate blood-leads for 

women; but using what is described in the report as it stands 

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now, we have some results for them, too. 

Again, you can see the small incremental 

improvements as you go to lower and lower standards in the 

mean: not _\s sensitive as children are at the higher end. 

Once we arrive at case study results that we. are 

comfortable with, we would like to incorporate them into the 

draft staff paper in early 1939. The staff paper will 

contain recommendations on alternative standards. 

The focus will be blood-lead levels of concern 

based on the criteria document assessment, whatever updated 

assessment that ECAO will wind up doing. We will also have 

recommendations on the aggregate time of the standard, 

monitoring frequency. 

Case study results will also be incorporated into 

the benefits analysis. That methodology was reviewed by a 

subcommittee last year. Those results will be incorporated 

into the overall regulatory impact analyses. 

Dave McLamb will talk about this by the end of the 

day. 

That is all I wanted to show you for now. 

DR. RABINOWITZ: On the hand-outs, on page 44 

where we have the results of the disaggregate model for women 

of child-bearing age, there is an asterisk and it refers to 

children. 

That is the end of it? 

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MR. COHEN: No. 

DR. RABINOWITZ: Maybe tha t i s fro m a differen t 

MR. COHEN: Yes . 

DR. RABINOWITZ: Okay. 

MR. COHEN: It should read "Women, 15 to 44 years 

of age." 

DR. MUSHAK: What do those refer to? 

MR. COHEN: The actual number of people that were 

within those areas. That is based on Census data. 

DR. MUSHAK: So we are talking about 20 people? 

MR. COHEN: 20 women in that age group: a really, 

small population, a lot more children. 

DR. MUSHAK: This is the City of Dallas? 

MR. COHEN: Yes. 

DR. MUSHAK: Intuitively, that seems like a low 

number. I don't know. 

MR. COHEN: 3 kilometers. 

DR. MUSHAK: Still, 20 pregnant women in 3 

kilometers in a big city— 

DR. RABINOWITZ: So for each of these 20 women, 

there is a certain air-lead, a certain soil-lead and then 

they do the mathematics? 

MR. COHEN: Yes. 

DR. RABINOWITZ: They get a distribution for each 

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129 

o f thos e 20 women and tha t .',;•: what i s shown her.--? 

MR. COHEN; Yes , 

DR. RABINOWITZ: So of the 20, there will be 

different air-leads, different soil-leads depending on — 

MR. COHEN: Depending on what block they live on. 

DR. RABINOWITZ: Okay. 

CHAIRMAN LARSON: You mentioned that you had 

predictions based on where people lived relative to the 

impact of air quality. 

DR. McLAMB: Precisely, we look at the Census 

data, the most detailed data that.we can get when we apply 

this to other places to see the impact of alternative 

standards. 

We pretend that it is like a geographic weighted 

average of where people are located within a Census tract. 

We use an ISC model to predict ambient concentrations under 

alternative standards. 

If there are people that are block-group-centroid 

for one receptor, then they will get whatever concentration 

the'model predicted for that receptor. Typically, we find 

several block-group-centroids within so many kilometers of 

these sources. 

We will have end groups of people with the same 

ambient concentration which, depending on the scenario we 

look at, will dictate the soil and dust levels. 

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Does tiat answer your question? 

MR. HAINES: We come up with a mean and then we 

predict the GSD from the mean. 

DR. McLAMB: Yes. 

CHAIRMAN LARSON: You have a variance predicted by 

the model which you use to just collectively use that 

information to compute a mean. 

DR. McLAMB: That is correct. 

CHAIRMAN LARSON: Then you predict a different 

various from the second step. 

DR. McLAMB: The second variance is given that we 

discuss earlier here. 

CHAIRMAN LARSON: We don't feel that the variance 

predicted by the model is going to capture all the variables. 

We are fortunate that we have data on this 

measurement. 

MR. COHEN: Are there any other questions on that? 

[No response.] 

Okay. Do we want to go to the next phase? 

CHAIRMAN LARSON: I think it would be useful to 

keep going here, if possible. Page 48. 

MR. COHEN: We have been talking about other 

applications of these methodologies. There are a lot of 

analyses within the agency and outside relating to lead. 

Naturally there has been a lot of interest in what 

) • ' EXECUTIVE COURT REPORTERS (301) 565-0064 

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has been going on in developing these models. We thought it 

would be useful to wet some feedback from the Subcommittee on 

the potential usefulness of extrapolatinc these methodologies 

t o o t h e r s i t u a t i o n s. 

Again, I don't have the slide but it is in your 

hand-out. There are a couple of other applications that have 

b een i d en t ifi ed . 

For example, we talk about Super Fund sites, leadcontaminated-soil problems. The Office of Drinking Water was 

interested in how to assess high-level peak intermittent 

exposures from school drinking fountains, for example. 

They thought the biokinetic model was an 

appropriate tool to measure the rapid changes associated with 

that. Land application of sewage sludge is another potential 

interested assessment. 

Similarly, municipal waste incinerators produce 

some lead from the stacks. There might be some relevance for 

some of these models. It may not be the biokinetic model, it 

may be the aggregate model. 

Relative ranking of different pollutants based on 

daily intake estimates. A lot of risk assessments in the 

Environmental Protection Agency are based on average daily or 

acceptable daily intake, and the uptake model produces those 

kinds of estimates for lead. 

The benefits analysis for the regulator impact 

EXECUTIVE COURT REPORTERS (301) 565-0064 
P.34 

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analysis is part of the lead NAAQS review. 

Dave will give you some background. 

D_!__ ______!__ Wj. McLamb 

'DR. McLAMB: The.reason we have been making a big 

point about this last item is because it is tied to the lead 

NAAQS. There are at least three people on this Subcommittee 

who reviewed the benefit analysis. 

I just want to remind those guys: we are using the 

outputs of the blood-lead modeling exercise we have seen 

today to generate the benefit estimates. 

A little more background. 

A primary motivation for doing the benefit 

estimates at least started in the Environmental Protection 

Agency from Executive Order 12-291 which requires us to do 

benefit and cost estimates for alternative standards we 

consider. 

Hence, we have, in the past, gotten some peer 

review on how we .might go about doing benefits. 

Equally important, we want to make sure it is 

fairly consistent with the scientific literature as it is 

graded, if you will, by CASAC. 

Basically, our benefit analysis for lead focuses 

on three different health end points, the first being on the 

chart up here: elevations in erythrocyte, protoporphin and 

blood-lead. 

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P.35 

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Basically CDC has designed protocols which define' 

how and when children are treated for lead toxicity based on 

these two parameter values. 

In our benefits analysis, we basically, for 

alternative standards, looked at how costs of screening and 

treatment vary as you lower ambient exposure to lead. 

The second benefit category we look at is 

intelligent quotient, or 10 decrements. As you reduce any 

kind of lead exposure—in our case ambient lead—there are a 

number of studies that show that 10, at least the average 10, 

will change for large groups of children. ' ... 

In our valuation methodology, we basically look at 

how the productivity of society changes as IQ improves 

marginally, and we measure that by looking at basically 

changes in expected lifetime earnings and stuff like that. 

There is a second sub-category of this IQ stuff. 

That has to do with cost of treating children who are 

severely retarded. 

If you change ambient lead by some amount, you 

will change blood-lead exposure which gives you the marginal 

change in 10, which again shifts the distribution: there will 

be slightly fewer children designated as being severely 

retarded and they will get less remedial education and 

treatment. 

The third benefit category we have been able to 

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evaluate has to do with elevations in blood pressure: quite a 

controversial category, I think, over the past few years. At 

least to date, we still plan to pursue that, only for adult 

rnales, though, I would 1i ke to ment i on. 

Basically here, when we estimate benefits, we look 

at the reductions in the costs of treating hypertensive 

males. 

Secondly, we look at the reduced cost.of treating 

cardiovascular and cerebral-vascular consequences of elevated 

blood pressure. 

I would like to make several comments in regard to 

qualification of the limitations and the benefits we have 

been able to estimate. 

We know there are a lot of other significant 

health effects that, at least currently, we don't feel we can 

quantify. Furthermore, the benefit categories we are 

estimating benefits for are for those categories we felt 

comfortable identifying as of early 1987. 

As far as we are concerned, the jury is out right 

now as to whether or not we can expand our benefit analysis 

any at all. We will wait to see what happens in the next 

full CASAC meeting. 

It is my understanding there are quite a few 

studies still out. 

In March 1987, we convened a Subcommittee very 

4 

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i. v. w 

much like this one. There were about two additional 

economists on it as well as members from the Health 

C o m m i 11 e e, fro m the f u 11 0 A S A C. 

We asked for comments. We responded to the 

comments at the meeting. We got closure letter from both 

Mort Lippman, co-signed by Bob Rowe who was the Subcommittee 

co-chairman, back in June 1937 I believe. 

We have incorporated those comments into the 

document with the exception of some comments I believe we got 

from either Dr. Mahaffey or Dr. Chi solm who said that our EP 

blood-lead relationships should be disaggregated by ARNstatus. 

We are currently modifying those physical effects 

functions that give us those benefit categories. Allan 

Marcus has been working with us on that. 

So we pretty much incorporate all the benefits we 

got except for the final change. 

We have yet to do any benefit estimation for these 

preliminary blood-lead numbers you have seen today because 

they were just available a couple of weeks ago. Again, we 

have not finished up the blood-lead EPA stuff on ARN status. 

Just to give you an idea how all this fits into 

the RIA, you will see a little block. On the top, it says 

"blood-lead exposure". That is what we have been talking 

about today. 

EXECUTIVE COURT REPORTERS (301) 565-0064 
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In the RIA, there are a number of analyses going 

on and they feed into one another in various ways. Ther--.. ..r. 

really other links that kind of feed on one another in s 

general equilibrium sense, but I don't want to cloud the 

discussion with that. 

In any event, the top row describes our benefit 

estimates. We look at baseline ambient concentrations and, 

using dispersion modelings, we estimate ambient baseline 

concentrations. Then we see how we add controls and how lead 

concentrations will change as we add controls to our ambient 

impacts- measure, which again drives blood-lead as we haye 

seen today. 

Changes in blood-lead will yield changes in health 

effects, and the health effects are valued as I just 

described. 

At the same time, the ambient impacts are driving 

blood-lead exposure all the way down to benefits. We are 

estimating engineering costs as we add controls. 

Then through a lot of simple-minded economic 

models, we estimate social costs. You put the benefits and 

the costs together and you come up with a benefit/cost 

analysis pretty much as the mandate in Executive Order 12-

291. 

That concludes my presentation. 

DR. MUSHAK: Let me understand. 

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The Clean Air Act says you will not consider-— 

DR. McLAMB: Absolutely. 

DR. MUSHAK: But you do this anyway. 

DR. McLAMB: Well, the President told us to. 

CLaughter1 

DR. MUSHAK: 01: ay. 

DR. RABINOWITZ: So you sort of closed in terms of 

health effects you want to consider for the purposes of this 

cost/benefit analysis? 

DR. McLAMB: We are closed to date until the full 

CASAC convenes again and looks at the new literature. .1 . 

believe we can quantify fetal effects, for instance. 

So right now it is fixed in time, but we pretty 

much have to take the lead until the scientific community 

comes to some sort of general agreement that we can actually 

value on. 

MR. HAINES: Isn't it true there are other 

effects identified in the literature that are well-accepted 

within the scientific community that you have problems 

evaluating? 

DR. McLAMB: And there are some nori-effects on 

which we don't have the physical functions, also: a subcategory of the ones we cannot quantify. 

MR. HAINESs So it is an interactive type. Before 

he can come up with benefits, there are several conditions 

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that ha ve t o be s a.i s f ie d. 

DR. RAEINOWITZ: So you don't warit just one paper 

that reported something. You want some kind of consensus 

t h a t t h is is a s i m i 1 a r p h e n o m e n o n ? 

MR. COHEN: No. We need to make the distinction 

clear between the benefits analysis arid the health-risk 

assessment that goes to tlie staff. We recommend a blood-lead 

level of concern will incorporate health effects whether or 

not they can be monetised. 

We are not ignoring those other health effects in 

setting the standard. In doing the benefits analysis, we 

have to draw the line that those effects that can be 

quantified in monetary terms. 

MR. HAINES: That is the point I was trying to 

make. 

David has two conditions on what does the science 

say about a health effect. We are going to use the total 

date set, a portion of which he may not be able to monetise 

and come with a monetary value on. 

DR. McLAMB: A good example is what is the value 

of improving forced expiratory volume? We had a tough time, 

as an economist, evaluating those kinds of health effects, at 

least to date. 

CHAIRMAN LARSON: Prior to some discussion among 

us here, I wanted to turn it over briefly to Bob for some 

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additional comments on the process we are involved with here. 

A_. _--_.-__.___L F*Laak 

MR. FLAAK: Before the Subcommittee gets into its 

final wrap-up today and some of the general consensus points 

that the Subcommittee wants to bring to the Committee's 

attention get gelled and finalised, I wanted to talk a little 

bit about the process whereby the Committee operations; and 

here I say the full CASAC, the seven-member Committee. 

For those individuals who are new to the CASAC 

process—Paul and Scott and Ian—this is primarily for you so 

you have an understanding of how we do business. For the. 

rest of you who have been involved in this before, it is a 

rearrangement of something you probably know a little bit 

abouit. 

This is a Subcommittee of CASAC. As such, its 

recommendations pass through the full Committee. 

CASAC is the only Committee within the Science 

Advisory Board whose recommendations go directly to the 

Administrator without passing through the Science Advisory 

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20 || Board's Executive Committee or Steering Committee. 

That is because CASAC is mandated as a separate 

committee by separate legislation and is merely housed within 

the Science Advisory Board for administrative purposes. 

As far as a Subcommittee is concerned—and all of 

our subcommittees are chaired by either a member of the full 

EXECUTIVE COURT REPORTERS (301) 565-0064 
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1 || CA3AC or by anot her member o f the Sc i enc e Advi sor y Boar d — 

2 || whatever deliberations and results come out of this mee-ting 

3 || today will be put in some kind of a concise, clear, toTMthe4 || point written form by Tim and I, at some point in the next 

5 || couple weeks after this meeting, and forwarded around to the 

6 other members of the Subcommittee for concurrence. 

7 Once the Subcommittee members are satisfied with 

8 tlie document, it will be passed on to the full CASAC seven 

9 members for their final sign-off at that point. 

10 There will be a lead meeting of the full Committee 

11 some time in the early part of 1989, perhaps in February or 

12 so. We don't have a firm date on that yet. 

13 At that time or perhaps earlier, certainly at that 

14 meeting, Dr. Larson will make a presentation which will 

15 summarise the discussions here, essentially laying to rest 

16 this document as far as that meeting coming up in February is 

17 concerned, which is the purpose of having this meeting today. 

18 There may be an opportunity to present this to the 

19 full seven-member Committee at an earlier meeting to get a 

20 sign-off on it or we may do it via the mail, which we often 

21 do when an issue is particularly controversial. 

22 There is an osone meeting scheduled in the middle 

23 of December, which may be an appropriate time to bring this 

24 report to the full Committee's attention for a few minutes. 

25 With that in mind, whatever final comments we have 

> EXECUTIVE COURT REPORTERS (301) 565-0064 
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J 

this afternoon we wiil look over with a great d..a 

interests. We will fold them together into what 

consensus p o s i t i on o f e ver yon e here. 

Thank you. 

CHAIRMAN LARSON: Prior to my task to trying to 

summarise—partly verbally here; but also hopefully, with 

some more considered thought, I will write something down, 

pass it around and we will all take a shot at it—I would 

like to get some sense from the Subcommittee members on their 

views on a few of the questions. 

CHAIRMAN'S SUMMARY 

CHAIRMAN LARSON: First of all, were the comments 

that you submitted and which were addressed earlier today 

address adequately? That is to say, are you satisfied? 

Given the fact that they might respond in the way that they 

did, do you consider that an adequate addressing of the 

comments that you have heard today? 

Will that be sufficient or are there additional 

comments or issues that were raised today that were not in 

any of those comments that we heard this morning? 

I have made a list here of some of my own that may 

be addressed directly or indirectly in some of the earlier 

comments. 

Are the modeling approaches reasonably structured? 

That is to say, are we in agreement with the types of 

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exposure models that we have seen, at least in their 

structural form is not necessarily the input numbers? 

Can we get some sense on this? There seemed to be 

a general agreement about the approach of biokinetic uptake 

for the children and some discussions pro and con about the 

aggregate/disaggregate models. 

Kate? 

GENERAL DISCUSSION 

DR. MAHAFFEY: I had an easier time with the 

biokinetic approach recognising it is missing huge amounts of 

information. 

CHAIRMAN LARSON: I guess that is the second 

question. Given that we are comfortable with that approach, 

are the available data to be used there used appropriately? 

I had a number of points that were possibly at 

least under some discussion: the number of milligrams a day 

eaten by young children; the issues of the constancy of soillead after rapid reduction in air-lead versus some 

correlation between the two. 

My feeling was there was some consensus that we 

should keep that soil-lead value constant, but- that the dust 

values perhaps are more responsive to the air values. 

The question of smoothing of the data for the 

intermediate-age children, I was not quite sure how we came 

down as a Subcommittee on that issue. 

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DR. MUSHAK: I gue:;--s in th e absence , of information -

eithe r way, probabl y th e rathe r abrup t approach i s if you ar e 

ears old , you have a...:., bed a lot ; if you are •• w . 

•z •-..• n s i u._ r ai. I y o 1 d e r ,V \ O. Li S tart lookiinq like adults. 

DR. CHISOLM; J would guess it would slow down 

from, say, six to ten and then you get in the adolescent 

growth spurt. 

DR 

DR. CHISOLM: It probably does grow with the 

growth rate. 

MR. COHEN: That is where we draw the line, . 

St. 

really, at six years old. 

DR. CHISOLM: Forget the terrible adolescence, 

right? 

ZLaughter 3 

CHAIRMAN LARSON: Another issue which was raised: 

Given the assumption of a relatively constant lead source, 

how do you estimate what that is in the absence of soil 

information when you go out and take this model elsewhere? 

There was some discussion about the differences in 

that steady-state air-lead/soil-lead relationship. Maybe we 

can take a look at how the results look. We can vary that 

over the range that we were discussing. 

DR. von LINDERN: Can I ask a question and get a 

little bit of clarification on that point? 

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It looks like one of those ends up hinging on th__ 

predictions of the air-quality model. I think all of it 

c o m e s b a c k t o t h a t. 

It seems it could be appropriate to me to go out 

and evaluate sites w here you don't have i nfor n. a t i on t o 

evaluate the impact of proposed standards. 

Are we thinking in terms of implementation that 

way as well? When we get to implementation, will we look at 

actual soil values in these locations'? 

Has anybody given that any thought? 

MR. HAINES: I think this got back to your 

question of the policy call. Our mandate is essentially to 

set an appropriate air quality standard. 

We are estimating taking into account soil/dustlead, food, total lead exposure; but we will be implementing 

an air standard, as the Administrator judges, providing 

protection with an adequate margin of safety. 

Separate and apart, you have the parallel issue of 

what do you do in the soil clean-up. So there is 

clarification in the legislative mandates between our best 

estimates of soil/dust-lead levels and trying to arrive at an 

appropriate standard, but when it comes around to 

implementation we will be implementing the air aspect of it. 

Super Fund and other people will be making an independent 

determination, to some extent, whether or not that soil needs 

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t o be cleane d up. 

There is not the jointness that your comments 

suggested at this point. 

Tliat may be a question we will have to discuss 

ourselves. It is B.n interesting thing you have laid out: 

whether or not it should be. 

DR. von LINDERN: Where we are at here is to 

evaluate— 

MR. HAINES: The air portion. Under the Clean Air 

Act, that is what we are here about. 

CHAIRMAN LARSON: One of the other inputs, perhaps 

which is mentioned but I did not get a sense of where we were 

with it, is this sort of community exposure issue versus the 

block or site-specific exposure. 

Is that or is that not something important that is 

important; and is it taken into account in your analysis? 

Ian, you mentioned that earlier. 

DR. von LINDERN: Again, I think that sort of ties 

in to the same thing we just talked about. There are 

situations around these point sources where we know a lot 

more than making a model estimate. 

In most cases, we could probably develop a better 

model; but as I understand it that is not something to do 

here. 

MR. HAINES: I think there are two issues here. 

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v.-Iter situation «t e.:t!;..r „_,,.-.t 

Helena or what you are seeing in your location. In >••.,_..•'..:, iri 

effect one source is dominating the .... oinmuni ty. "!"!••: -.:•: • •. fii ...t:-,.- 7 v 

is impacted by that source-. 

By the same token, when we did our evaluation in 

East Helena we were basically impacting just about all lhe 

kids in that. Where we transfer this to an urban area, say 

Dallas, that source is affecting a relatively small area 

around there. 

I guess I am trying to differentiate is that a 

community in East Helena, which I know better than Silver. 

Valley, is probably the whole town influenced by the smelter 

or at least a good portion of it as opposed to a Dallas 

situation where it is only a small geographic area of the 

city. 

I am not sure if we are far apart on what we are 

doing here. I think we are using different words to say 

basically we should be looked at the sone of influence of 

that stationary source. 

CHAIRMAN LARSON: This gets to the question of 

given that we have a structure that we are comfortable with, 

available data, there was some discussion of various 

uncertainties that need to be looked at in terms of the final 

output, as inputs. 

Are the proposed applications of these approaches 

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P.49 

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reasonable? That is to say, in this case, the biokinetic 

uptake model applied to tlie children and perhaps, or perhaps 

not, some disaggregate model applied to the adults or some 

set of adults. 

I get a consensus that the application of the 

first model to the children is most appropriate, but I am 

still not quite sure about what we do with the disaggregate 

model and the pregnant women or not, or whether or not there 

was some consensus about that. 

It seems certain that there was not much 

information at all on the fetus, and we should probably make 

sure we stay clear of that. 

DR. MUSHAK: I suppose they could have equal 

billing. 

Jeff and I were talking a little bit at lunch 

about using this as a data point for the newborn, at point of 

birth with some assumptions, and using an adult model hybrid 

of this plus what Mike had published to try to come up with 

something for women and do an adjustment for the women's 

lead. 

That is, to an adjustment for the resorption: try 

to be as generous with that as possible. 

After that, there is an option. That is, you are 

not really looking at a quote/unquote in-utero span. You are 

ginning another data point that is not available, and it is 

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probabl y 

model 

_.. _. .r . i '-... ._: i O U q r 1 t o _>t--,

_. "•'.. e 

-••er the other is .he question, 

CHAIRMAN LARSC..: I think we can certainly express 

the fact that these are important groups to consider, and 

that we sure wish we had more data tlian we do to be able to 

perhaps do it better. 

DR. MAHAFFEY: I find this hard to really say what 

to do with. I don't think anybody wants to create a 

situation where it looks as though looking at pregnant women 

and the fetus is not something to do because, in terrnsrof the 

health research, that is a group that is extremely important 

to consi der. 

The other side of it becomes: How do you do this 

and do it with some degree of sense in the process? 

We are kind of hard put to come up with an answer. 

It sounds as though if there is something in Yugoslavian data 

where you can get some blood-leads over time during 

pregnancy, you might have some information to work with. 

There is always a temptation to say, "Sure, go 

ahead and make this model, see how it looks."' The difficulty 

is after we have done that, we sit and say, "Well, we are 

glad you did that. It was a good thing to do." 

We have this model now. There is always a chance 

someone will pick it up with a few more sets of assumptions 

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in it. 

I keep wondering what are we creating in the 

process of doing this. 

DR. MUSHAK: That would be the inherent risk with 

the Environmental Protection Agency running amuk with the 

generic realisation. 

MR. HAINES: Realistically, this brings me back to 

ths question I posed before. 

If, in the collectively judgment of the 

Subcommittee, we don't think we are in a position to 

appropriately model and assess this risk in a quantitative 

way, because we don't have the tools and don't have the 

data— 

I want to make sure we don't go down a pathway and 

do something that nobody has any confidence in because of the 

absence of data. If that is the case, maybe we ought to so 

state and say, "We are not in a position to estimate these 

exposures at this point in time. This is the research that 

will have to be carried out over the next several years so we 

can answer that question." 

What I am trying to avoid is we could take the 

approach laid out in the paper,—you know, the alternates— 

put in that caveat, indicate they were developed for adult 

males, have applicability to pregnant females. That is up in 

the air. 

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We know very little about the biokinetics taking 

place, but we will produce an answer. 

What I guess I am saying is that if, in the wisdom 

of people here, if that answer is not wort I'i the paper it is 

written on, why take the time to produce it? 

CHAIRMAN LARSON: We simply are not telling you to 

completely ignore the subject because we feel it is an 

important target group. While it is an important- target 

group, there are other ways we talk about it in a qualitative 

sense; but we cannot predict what is happening in the future 

on this. 

DR. MAHAFFEY: It is my experience with caveats 

that this is like doing tables and somebody picks out a 

couple of numbers and says, "Yes, this is what you said." 

It is a very important group, but in terms of the 

biokinetics, unless there is a lot more in this Yugoslavian 

data than perhaps others have been aware of, I think we out 

where we don't want to make high the house of cards. 

MR. HAINES: The bottom line, as I interpret it, 

is that we proceed to try to quantitate those exposures. 

Then we will rely on the biokinetic model to estimate 

children's blood-leads. 

We will look at adult males from the point of view 

of hypertension effects and have to discuss, in exposure 

terms, the change in female/fetal very much in a qualitative 

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P.53 

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sense in not being able to predict in the future what change:;: 

the air-quality levels nay have. 

DR. MUSHAK: Katie, if no one is advancing *ny 

Yugoslavian data as important> if they are elevating it to 

the status of a useful data set, all that has t.appened is 

that some mention was made about there ar e se-r-rial measures. 

They p r o b a b 1 y have s o m e i d e a o f a i. r -lead 1 e v els. 

DR. MAHAFFEY: Where I think we are, apparently 

there are a few results on pregnant women in the work that 

Bill Manton did—which is, what, maybe on three subjects—and 

there is some other anecdotal kind of information that is 

suggesting that blood-leads may go up in pregnancy or may go 

down in pregnancy. 

If we are not sure, because of prior exposure 

histories in mobilisation probably of blood-lead, whether or 

not the blood-lead is going to go up or down, trying to 

relate that to a current air level strikes me as extremely 

chancy. 

DR. RABINOWITZ: It is hard for me to understand 

what the significance is of sequential blood-leads during 

pregnancy, whether they go up or down. I can'imagine a 

situation where blood-leads go down. That means lead goes 

into the fetus. 

I can imagine a situation where the blood-lead 

goes up. It still goes into the fetus. 

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So it is hard for me to know what to make of the 

health effects of whether the blood-leads go up or down in 

pregnancy. 

DR. MUSHAK: Blood-lead going up or down does not 

necessarily mean the fetus becomes a sink. Other things 

hap pen to lead. 

DR. RABINOWITZ: That's right. 

DR. MUSHAK: It gets excreted. 

DR. RABINOWITZ: It could be excreted or it could 

go to the fetus. I just don't know which it is. 

DR. MUSHAK: Oh, I think it goes to the fetus, but 

not exclusively. Let's quality it. 

DR. RABINOWITZ: I have heard the placenta called 

the third kidney. Maybe the placenta is a sink for this 

lead. 

So whether or not the blood-lead go up or down, I 

don't know what to make of that. I have enough faith, for 

some reason, in biokinetic modeling that if you somewhat 

diddle with the model and you do the right things, you might 

approach what is going on. 

I like all the caveats you said about maybe it is 

not worth doing if you cannot do it right. I agree with 

that. 

I would like to draw just one possibility to maybe 

fine tune it a little bit, that might be helpful. 

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Can we take a leaf •

from the calcium- story in 

pregnancy and say, "Okay, if you are pregnant the FDA, in 

their wisdom, tells us we need this many more grams of 

calcium per month or something," and then say, "Well, iri the 

human body tire ratio of lead to calcium is some certain 

number, depending on if you are high in lead or low in lead." 

Then we can say, "Okay, for every gram of calcium 

you require, that is equivalent to how much skeleton you are 

losing," and get an idea of how many micrograms of lead are 

entering circulation from the skeleton from that. 

DR. MUSHAK: But you still need' a subject variable 

bone-lead burden, and you can easily get it. 

DR. MAHAFFEY: The question are: Is the skeleton 

equally labeled? Is it equally available? 

This is where the data is so limited that we did 

not know what to write except that it seems reasonable, for 

whatever reason,—"reasonable" used in a strange way here: 

for lack of anything else to say about it—that there are 

probably physiologically many small pools of skeletal calcium 

in lead levels that are resorbed at different times. 

CHAIRMAN LARSON: The lead in the Calcium? 

DR. MAHAFFEY: Yes. I don't think we know. 

CHAIRMAN LARSON: This has served a useful purpose 

in the discussion highlighting the fact that there is a 

paucity of data in that area. 

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DR. MAHAFFEY: We have something in Envj.^onm_;nt-___ 

Research that is out in a month or two that is showing some 

increase in blood-lead. There was one question in NHANES 

about menopausal status: that post-menopausal women have a 

slight increase in blood-lead. I think it is about 15 or 20 

percent. 

That is not dealing with people who are 

specifically osteoporotic. If you had this specific 

osteoporotic group, it would seem reasonable that the 

increase is substantially greater. 

DR. MUSHAK: I don't know that Tyrol had broke out 

a physiologically discernible osteoporotic. I believe it was 

an age-found analysis. 

When you analyse the same data, you better come up 

with the same answers. 

DR. MAHAFFEY: We hope so. 

CLaughter] 

DR. RABINOWITZ: Does it depend on whether or not 

they take estrogen? Do you have that information? 

DR. MAHAFFEY: I don't think that was in it. 

CHAIRMAN LARSON: I guess we will leave it at 

that. 

Another issue, the second one I would like to 

discuss, is sort of a second model, which is the proposed 

approach to estimating the variance in blood-lead using the 

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geometr i c st andar d deviati on. 

Is that approac h acc.eptab 1 e to the Subco .imi 11ee? 

We heard from Ian some comments about possible examination of 

the range of values. That might be a useful part of the 

exerci se. 

Do you think it is necessary to look at a range of 

GSDs in this? First of all, are we comfortable with this 

approach? 

You saw it used here in the case study where there 

was a mean computed and then a variance about that mean that 

was computed for those plots based upon the GSDs. 

DR. MAHAFFEY: I think there are two problems, at 

least. 

One is that the coefficient of variation just due 

to analytical as the blood-leads go down becomes bigger: that 

they have to somehow deal with that. 

I think that we are talking about blood-leads of 

under 10 and definitely under 5. This is a range that, given 

the NHANES was used for that data set, we did not have very 

many blood-leads under 5. 

So there is a lower boundary on that that is 

unclear what happens there. 

CHAIRMAN LARSON: Are you looking at levels in 

your NAAQS alternative assessment if you are thinking about 

this at those levels? 

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MR. COHEN: Yes. There will be s whole lob of 

children at lower levels tK-.n what we are dealing with now 

no matter what we do with the air standard. 

'We presented a range of GSDs in the report. We 

decided to pick one just to simplify things. Otherwise on 

every table we can come up with we would have four more. 

We need to sort of focus the analyses down to a 

manageable level. We could look at the higher end of the GSD 

range as presented as the conservative choice. 

We decided to pick a mid-point because we are not 

sure what is going to happen in the future. It is a really a 

tough cal1. 

MR. HAINES: The analytical variation, I think, of 

the lower blood-lead levels are a serious problem. We have 

the problem with the underlying health studies, too, which 

had the same problem associated with them. 

I think our feeling is, A, if you can correct for 

it, B, is it appropriate to? You correct it on one side of 

the equation and it is uncorrected on the other side of the 

equation doing that. 

That, to me, is a perplexing problem how to 

address: A, what would you do in the first instance to fix 

it, if we could; but, B, do you fix part of it and then you 

still rely on the health effect studies for which it was not 

corrected. 

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MR. C0HEN: There is a pre11y substantial 

discussion in the criteria document on correcting for 

analytical variation and the effect on the GSDs from NHANES. 

We did find a smaller variance after correcting for the 

analytical variance. 

For adults I remember it was 1.37 for urban whites 

versus 1.33 if you do make the adjustment. We thought it 

was, like John said, inappropriate though because we would be 

correcting on one side and not the other. 

DR. MAHAFFEY: Again, those were for blood-leads 

in, what, 15, 20, 25? 

MR. COHEN: Well, these were adults. They were 

10, 15. 

DR. MAHAFFEY: I don't have the answer. 

MR. HAINES: I think the only approach is to make 

it clear in our report that we have made the correction.- I 

think you have to proceed. 

I don't know how we could do it and whether or not 

it would be appropriate without making an adjustment across 

all the data bases. I am not sure we can do that. 

I think sometimes it introduces a degree of 

uncertainty in the results, but all we can do is point out 

that this exists, unless Jeff or Allan, or somebody, has a 

solution for the problem. 

I think it is one of recognition and you have to 

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1 move or,. 

2 CHAIRMAN LARSON: Mathematically speaking, it i. s 

3 presumably a more sensitive parameter than a simple 

4 multiplicative factor that you might be changing by a certain 

5 value. 

6 My only perspective is it is a sensitive parameter 

7 to the final outcome. So you don't have to necessarily run 

8 all the detailed numbers, but give some sense of how 

9 sensitive that sensitive parameter is. 

10 DR. RABINOWITZ: On this sensitive parameter, we 

11 don't have any sense for the range it could acquire. 

12 MR. HAINES: That is the problem I see. 

13 We know it probably exists, but we don't have any 

14 notion of what it is or what the magnitude of it is. 

15 DR. RABINOWITZ: The GSD itself?-

16 MR. COHEN: Of the ratio between that and the 

17 mean. 

18 DR. RABINOWITZ: There is a table in the document 

19 showing a whole bunch of different numbers. Then we heard 

20 about the same set, perhaps even a more limited range, that 

21 Ian mentioned in his study. 

22 I am quoting numbers 1.3, 1.4, 1.5 and 1.6. 

23 MR. HAINES: I think we were talking more of the 

24 analytical variation that impacts at this level — 

25 DR. RABINOWITZ: Oh, I'm sorry. I misunderstood 

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MR. HAINES: —vis-a-vis GSDs that Jeffrey 

discussed in the report. 

DR. MUSHAK: As an aside, I guess, the analytical 

variance you see in the NHANES data set is not a v&ry good 

analysis. You recall that was one of the arguments a the 

time that were used to argue counterpoint. 

One could show that by the good quality of the 

NHANES data-gathering analysis. I am not sure you could get 

as much with any other data set, and certainly not with it as 

it shifted the mean for the analytical challenge you have.. 

It is just not going to do it. 

DR. von LINDERN: I remember I prefaced what I 

said.with a guess. It was not quite a guess, but I think 

you have done a good job in creating this subject. 

I think your point is well taken: it is a very 

sensitive parameter. That is really what I felt is the gist 

to indicate that. 

DR. RABINOWITZ: This shows up again when you 

actually try to see if these standards are being met. By 

looking at blood-lead, you can see false positives or false 

negatives. 

It is the same problem showing up there also, I 

guess, basically. 

CHAIRMAN LARSON: Finally, on page 48, the 

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1 question: Can these modeling approaches we have discussed be 

2 applied t o o t he r e x p os u re set s ? 

3 This may not be an all-inclusive list, but it 

4 gives some examples of what — 

5 DR. MUSHAK: We would want to go down the list, 

6 would we? 

7 This model has a high potential for mischief if 

8 the Environmental Protection Agency and other offices get 

9 their hands on it. I mean that. 

10 MR. COHEN: Yes , please. 

11 DR. RABINOWITZ: Is it worth making a list of 

12 places where it should not be used? 

13 MR. COHEN: Yes. 

14 DR. MUSHAK: I think that is almost an infinite 

15 list. The thing is let's go with what they have . 

16 I think on the Super Fund sites, I think there is 

17 the caution indicated earlier. If one has some idea where on 

18 is, fine: that is, if you can assume that the pre - and post19 differential is at least in a linear segment of the overall 

20 curve. 

21 The high-level intermittent drinking-water 

22 exposures . I think that is less troublesome. In other 

23 words, the only variable that you need concern yourself with 

24 is how much lead was taken in: that is, if you have a child 

25 consumption rate during the day—30 0 mills is one number 

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coming out of the Minnesota sch-oo.1 survey , I not.! ced—arid i f 

you , say , hav e __:00 microgram s |;:-_-r lite r wit h standin g w.-ter f 

you get an amount of lead i n wati-r and you coul d pump i t int o 

... i.. .: _ .....t. i C h i __ I (I O'.it. J. . 

I think that, again, based on the Scotish data— 

and I think that is the main caveat here—unless you are way 

off those levels, again you are in that non-linear portion. 

You may want to add c omments to t hat. 

But I think for even 100 to 200 micrograms per 

liter excursions for water lead, it is probably okay. 

CHAIRMAN LARSON: I had some comments on the . 

drinking water, which were that even though I don't doubt 

that it is probably a reasonable thing to do it is not clear 

to me that this particular document lends credence to that. 

I guess it does. The validation exercises assumed 

a constant drinking water lead level across all the different 

areas. So it really did not test it. 

DR. MUSHAK: But the original validation of the 

model was dietary lead. Those were feeding studies. Those 

were not air chambers. 

CHAIRMAN LARSON: So find support for it in one of 

the sub-modules here. 

DR. MUSHAK: I think you could probably make a 

good case. 

CHAIRMAN LARSON: It is implicit you have to 

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accept that particular study in order to accept this larger 

attempted model. In that sense, this does validate that. 

DR. MUSHAK: I think the over all restrict:on on 

the model is that it stay in some linear range. 

Consequently, all of your- inputs and uptakes from different 

sources of pathways should give you some indication that you 

are going for that medium in the linear range. 

You are barring empirical data to do that. 

MR. COHEN: Okay. 

DR. RABINOWITZ: Are there any caveats besides 

1inearity? 

DR. MUSHAK: Of course. I mean, by definition, if 

you have a bolus of exposures from drinking water or anything 

else given and if you have your typical, say, suburban brand 

new plumbing lead-soldered drinking fountain and otherwise 

the child is wel1-nourished, et cetera, unless you test that 

blood-lead level and have it persist, then I am not sure what 

the toxicological point it. 

That is, you can go through an exercise and say 

the child's blood-lead would have been that high, but I don't 

know what to do with it in terms of regulating it. 

DR. MAHAFFEY: To me, there are lot of things to 

be considered here in terms of the patterns of exposure. If 

you have a short-term high exposure of lead in something like 

drinking water, at least for children, I am not sure we 

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reall y have th e experienc e of understandin g what th e 

physiologica l response i s going t o be: i f thi s absorbed . 

Is i t mor'-- likel y simpl y t o be excrete d or are you 

goin g t o ha-^e a transien t hig h blood-lead ? 

I don't think we know. 

MR. COHEN: We don't, but I guess the Office of 

Drinking Water, nevertheless, wanted to know something. 

Anything that, I think, we would export to other 

programs we would try our best to couch it in all the 

appropriate uncertainties and try to make necessary 

adjustments. . 

I don't think we would use the same exact input 

parameters for all other applications. 

DR. MAHAFFEY: Again, as you said, it is explained 

in the set of circumstances you note: 30 percent of the 

var i ati on. 

If somebody wants to take this without having as 

much information as you have and say, "Okay, we can do this," 

and "Gee, this time we will explain 20 percent," I don'*_ find 

that encouraging. 

MR. COHEN: If you try to predict individual 

blood-leads, it is right. 

DR. MUSHAK: What exactly are you objecting to? 

Are you objecting to the notion that if a child drank 100 

micrograms of lead in water in a given day, nothing would 

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t tha t th;.- model i :•. .-nor 

for a chr oni -.. dai 1 y 

happen? 

Is that the point, or i: 

useful vis-a-vis similar calcuiati. 

c h i 1 d e x p o s u r e ? 

DR. MAHAFFEY: I guess my reaction—an d this is 

being kind of blunt about it — is that if we take pec.pl e who 

are going to drink water that is high in lead, it is 

reasonable to think the blood-lead is going to go up. 

How much do we really have to prove that it only 

goes, up 5 percent, 3 percent? 

DR. MUSHAK: But I think the Office of Drinking 

Water is not in the business of saying, "Well, obviously it 

goes up." I think they would like to hang a number off of 

that. 

The question is: Can the model be used to relate 

X micrograms in a single-shot exposure with a child to 

micrograms per deciliter? That is the issue. 

On the face of it, I would say that given that box 

you could put around it, yes. I think you have less of a 

problem with this than in the prior case: the Super Fund 

sites and so on. 

Whether or not you have anything useful out of 

that I think is the more relevant question. If you could 

convince the Office of Drinking Water that, "Well, yes, we 

can give you a number; but what is its meat and potatoes in 

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terms of regulation?", that is another thing. 

CHAIRMAN LARSON: That component is a part of our 

model and our model validation, but it is certainly not 

individually tested as a component in and of itself. 

Certainly there is evidence and part of the review 

process here gives us support for the fact that you can use 

that approach, but it would be misleading to say that this 

review committee gave a calibrated model to the Office of 

Drinking Water. 

MR. HAINES: I think what I am hearing you say is 

that any time a model is exported, this one in particular, 

anybody using it has to approach it in a very cautious manner 

and make sure, in fact, the model produces plausible results 

for the application for which it is being used. 

DR. MAHAFFEY: If one wanted to study lead in 

drinking water, there are studies that have been carried out 

in Scotland that have looked at lead in drinking water. 

MR. COHEN: Yes. 

DR. MAHAFFEY: Why not do that? 

MR. COHEN: They use that where they can. 

DR. MUSHAK: You can pose that in relation to this 

model. You have the smelter studies. You have East Helena, 

et cetera. 

Why do it in aggregate/disaggregate models? Why 

do it biokinetically? 

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16C 

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very high intense peaks. The Scottish data really don't 

pr ovi de t he n _••>:: _.••- sar y rel at: on ..h i ps. 

'DR. MUSHAK: That is quite fixed, high but 

c o r "i c s n t r a tec'. 

CHAIRMAN LARSON: Are any of. these lists or other 

items blinking out at you as being particularly dangerous 

applicat ions? 

DR. MAHAFFEY: What about relative ranking of 

different pollutants based on daily intake estimates? 

DR. MUSHAK: I would think that that is somewhere 

between 40,000 and 50,000 feet high up there. 

[Laughter 1 

DR. MUSHAK: And rising, yes. 

MR. HAINES: As far as modeling is concerned, 

there is no way we can produce a model that can have an 

idiot-proof cap on it. 

CLaughter_ 

MR. HAINES: What happens is that if the models 

are used by offices within the agency, the use of those 

models and the appropriateness of the input parameters will 

be examined by advisory committees as this use has been, and 

the Office of Drinking Water's use of the model will be 

reviewed by SAB. 

So I think the appropriateness of the model for 

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the air-lead standards is what we probably can appropriately 

focus on right now and let other people worry about the other 

applicat ions. 

I think we tried to provide a clear statement of 

our own r eser vat i on s about t he app1i c abi1i t y and t he 

appropriateness of the parameters, and we have been 

responsible in our use of those. That is. as much as we can 

do for anybody. 

CHAIRMAN LARSON: I think there is also some 

pressure to get reservations on the record early. It may 

well turn out that some subsequent committee using this, data 

can come up with something. 

MR. COHEN: It is like anything else in the 

scientific literature. 

CHAIRMAN LARSON: It is relative to the point in 

time. 

DR. RABINOWITZ: Is there somewhere in there that 

you say this should not be used for other pollutants? 

[Laughter D 

DR. MAHAFFEY: I would say that the Clean Air 

Science Advisory Board appears to have a lot more lead 

consultants to it than some of the others. So I think the 

amount of lead review in the air part is based on 

observation, it seems, more than some others have. 

So while we cannot defend this model against other 

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incursions or other inappropriate uses, we do need to bear inmind that the air part Iras been very much reviewed. 

MR. HAINES: My guess on this topic, from'my 

perspective from what I am hearing us trying to say, is the 

Subcommittee would go forth as far as, quote, exporting the 

model: that your view is it should be undertaken with caution 

by other programs and appropriately reviewed as to its 

applicability across the board. 

I think you folks can put the cautionary note on 

this and make it clear that it should not be endorsement for 

purposes it within the air standards. That should not.be. 

construed as a blanket endorsement to all other applications. 

I think that is the point you are trying to get 

across. I think that is a reasonable prospectus. 

CHAIRMAN LARSON: I have made up-my own list, but 

are there any other points that you would like to raise that 

you think impact the question of whether or not this becomes 

an adequate supplement, if you will, to looking at the 

alternate air-quality standards, given all the caveats of 

this written summary? 

I am not sure everybody is pi eased with it, but 

are there any points I have missed? 

Go ahead. 

DR. RABINOWITZ: I just had a wish that when the 

results of the calculations of these models are presented 

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only two significant figures are displayed. 

[Laughter 1 

MR. COHEN: I needed tliat, too. I kept the m-.arblood-lead to that, but the percentages T agree on, given ••'••e 

history of how some of our standards have been set: the .005 

percent of the population, for example. 

CHAIRMAN LARSON: Do you have anything else? 

MR. HAINES: I just want to make sure that I am 

understanding what I am hearing in summation. 

Going down your list of questions, as far as our 

response to comments posed by the Subcommittee, I think.I.am 

reading you as saying what Jeff has laid out: The way in 

which we plan to approach these is appropriate and adequate. 

With respect to the models, I am reading the 

Subcommittee as saying the application of the biokinetic 

model for children has a reasonable approach for estimating 

child blood-lead. 

When it comes to females, there is a great concern 

over the appropriateness of the approach. We should make 

this clear and try to explore any other ways we can address 

that in a better fashion. 

Where I am drawing the line is—and this is why I 

am coming down to the point—that one interpretation is: Do 

what we laid out; see if we have augmented the Yugoslavian 

data or any other sources; but make it very clear that, based 

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on adult males, not females, et cetera, or altevnati•ely only 

discuss exposure to qualitative sets and don't try to 

quantitate because we don't h.-e appropriate tools. 

CHAIRMAN LARSON: I could get wrong, but I got the 

latter as the sense of the Subcommittee. 

MR. HAINES: Okay. That is why I am posing it. 

DR. MAHAFFEY*. And strike the word "female" and 

use "pregnant woman" because it is not females, per se. 

MR. HAINES: I recognise that. 

DR. MAHAFFEY: The occupational people have a 

whole lot of trouble with that. 

MR. HAINES: Okay. 

CLaughter3 

MR. HAINES: In use of DSDs and that, I think we 

have laid out a range. I think the approach is agreed to by 

ther Subcommittee. 

CHAIRMAN LARSON: We had some discussion about a 

couple of those key parameters that go with the biokinetic 

model, just looking at the sensitivity analysis on the 

predicted soil-lead. 

I guess those are the two issues that were brought 

up and discussed. 

Anybody else? 

DR. McLAMB: I was not being facetious about 

estimating blood-leads in adult males. I would like to know 

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CHAIRMAN LARSON: We have not discussed that 

fully. I guess we were comfortable that there was adeuquate 

data for going ahead with that approach. 

DR. McLAMB: Okay. 

CHAIRMAN LARSON: We will draft something, 

hopefully, to the point that we can pass around here by way 

of summarising what we just discussed, some guidance. 

Thank you all for patiently meeting here this 

afternoon. 

MR. HAINES: I want to thank the Subcommittee 

members for working hard on this. 

CHAIRMAN LARSON: With that, we call the meeting 

adjourned. 

CAt 4:05 p.m., the meeting was concluded.] 

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