OAR Box 1113 

Prepped by Ryan Dugan 

Document Number: 

3) ll-F-3a 

Docket Number: 

A-83-22 

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U..ITED STATES ENVIRONMENTAL PROTECTION AGENCY 

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CLEAN AIR SCIENTIFIC ADVISORY COMMITTEE 

SCIENCE ADVISORY BOARD 

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U.S. E.P.A. 

Environmental Research 

Center 

Main Auditorium 

Alexander Drive and 

Route 54 

Research Triangle Park, 

North Carolina 

The above entitled matter came on for hearing 

pursuant to notice at 8:40 p.m.: 

PANEL MEMBERS PRESENT: 

DR. MORTON LIPPMANN Chairman 

MR. ROBERT FLAAK, Executive Secretary 

DR. CAROL R. ANGLE 

DR. J. JULIAN CHISOLM, JR. 

DR. BEN B. EWING 

DR. ROBERT FRANK 

PROFESSOR A. MYRICK FREEMAN III 

DR. ROBERT GOYER 

DR. PAUL B. HAMMOND 

DR. LLOYD G. HUMPHREYS 

DR. TIMOTHY LARSON 

DR. KATHRYN R. MAHAFFEY 

PROFESSOR M. GRANGER MORGAN 

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PANEL MEMBERS PRESENT: (CONT.) 

DR. TERRY YOSIE, DIRECTOR 

PROFESSOR ROIER G. NOLL 

DR. D. WARNER NORTH 

R. ROBERT D. ROWE 

DR. ELLEN K. SILBERGELD 

DR. JAMES H. WARE 

DR. JERRY WESOLOWSKI 

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AGEND A 

Statement of Richard Smith 

Questions and Remarks 

iStatement of Dr. Charles Pfeifer 

Questions and Remarks 

'Statements of Dr. Wallsten and Dr. Whitfield 

Questions and Remarks 

Committee Discussion 

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CHAIRMAN LIPPMANN: We thank you again for your 

willingness to come back today and help us spread the schedule 

There is a handout from Mr. Smith that we'll be discussing j 

some of the points we'll be talking about. j 

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MR. SMITH: The Mineral's Availability Field Office i 

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in Denver has been involved in the last few years in evaluating! 

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the technical and economics aspects of meeting more stringent j 

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air quality requirements on non ferrous metal smelters. ; 

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We have been involved in looking at the lead smelt- \ 

ing refining industry for a matter of two years now and have j 

a report which will be available very shortly and may be of j 

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interest to this Committee. Essentially, what is covered by the 

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report, we have taken a look at four of the six facilities in \ 

the United States. 

These include Glover, Buick and Herculaneum in 

Missouri and the East Helena Plant in Montana. We've considered 

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it from the point of view of what the lowest limit is technic- j 

ally feasible from these plants, without regard to any existing 

standard or proposed standard, based on current technology, 

how- low can emissions be gotten. 

We've not been able to compare them to ambient air 

reauirements because our facility at present does not have j 

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computer modeling capabilities. So our results are presented 

in the form of lead emissions on a per pound, pounds per day 

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I basis, 

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I The bases for the report uses publically available 

:data in the form of emission inventories from state implementation plans and. the annual reports that supplement those. 

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Contract studies performed for the EPA, plant visits and data i 

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collected at the plants, performance data on various emission j 

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^control devices from vendors, and personal experience on my j 

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part for the last 18 years and Mr. Kiehn, the co-author,' for : 

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a oeriod cf approximately 30 years. j 

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The method we selected as being the basis for the 

.design consideration would be dry collection, using bag houses,] 

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jar. enclosure of the existing buildings on the plant sites. j 

iThe reason for this was covered in two areas. j 

; First of all, point source emissions are being 

'collected presently at greater than 99 percent efficiency. 

Very little improvement can be expected in those areas. 

Process fugitives on the other hand, are being 

icollected in the realm of 70-90 percent efficiency, and do alio 

for improvement. The open fugitives only account for roughly 

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8 percent of the total emission of the plant and were deemed 

to be of little improvement for the amount of money that could 

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ibe expended. 

j Following our analysis — excuse me, one more point. 

W 

>7~e went to the dry collection because using other methods such j 

as wet scrubbers would create another environmental problem in 

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water pollution. And we felt that this was an unacceptable 

alternative. 

Our evaluation indicated that an overall plant i 

[efficiency for these four facilities which presently is around 

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j 98.1 percent, could be improved to approximately 99.4 percent, j 

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j This improvement would result in capital cost of approximately i 

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$100 million with an annual operating cost of $13.6 million. 

Certain assumptions were involved in this in considering that 15 air changes per hour for each building would be j 

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an acceptable figure. This is based, on information from the ; 

El Paso smelter which has enclosed one of their facilities. j 

The second consideration is at an air to cloth i 

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ratio in the bag houses of 3 to 1 would be acceptable. The i 

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industry, however, uses a 1 to 1 air to cloth ratio in most I 

cases. j 

Therefore, there is a discrepancy between vendor 

information and that used by the industry which we are presently 

studying to determine which is more correct. If "the industry's 

consideration is more correct, then we are looking closer to 

$300 million in installed capital costs and an appropriate 

increase in the operating cost as well since it would be 

primarily an electrical energy and maintenance manpower. 

Now, this basic number overlooks one important 

consideration. Enclosure in the building creates a problem 

from occupational health and safety perspective. 

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i :• To compensate for the increase in lead levels within 

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2 i'tr.e puildinqs, an additional sum of monev would be involved 

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3 |jin providing ventilation for specific unit processes within 

4 7 the plant and. special handling features for materials and col-

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5 i'lecte d wastes. 

. 5 j, Informatio n which I receive d yesterday , which unI; 

7 jj fortunately is not on the one page handout I have here, indicates 

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3 :; that to' additionally comply v/ith OSHA requirements, a minimum j 

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9 i cost total including our basic assumption, the capital cost j i

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 : -vouIf approach $250 million and an annual oceratinq cost of 

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i, ij$23.4 millio n pe r year. | 

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1 2 ji Acain, the air to cloth ratio needs to be adjusted 

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13 !, on the bag house configuration or other considerations need to ; 

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14 i: be taken into account, this figure could go considerably higher. 

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.- ij There's an overall view goinc back into the initial considera-

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'jtion, a minimum of 3 cents per pound of refined lead would be 

the added, cost for this type of an improvement. 

The result would be on the order of a 500 short ton 

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per year reduction in emissions from these four specific 

smelters. Again, that does not:.include the El Paso smelter, 

because it's presently shut down and it does not include the 

Omaha refinery which has specific problems unique to itself. 

The information which I've covered here will be 

!j available in an open file report in the very near future from 

the Bureau of Mines in considerably more detail. And we would 

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1 like to offer it to anyone who is interested to include in 

2 their analyses of the problem. As I say, we have not carried 

3 our numbers beyond an emission summary in terms of pounds per 

4 i day because of the computer modeling aspect 

5 However, because we are assigning the emissions 

5 specifically to point sources and fugitive sources, it should 

7 be a simple matter for any interested individual to apply this j 

8 to their computer model. 

9 That pretty much covers the extent of it. Are there 

10 any questions9 

n CHAIRMAN LIPPMANN: Thank you very much. I guess 

12 I could raise a couple of questions. 

13 QUESTIONS AND REMARKS: 

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CHAIRMAN LIPPMANN: I think it would be easier for 

us to grasp this material which is a bit outside the normal 

activity of many of the people here, if you would have presented 

the changes'in penetration values, rather than collection effi-j 

ciency values. 

When you say .8 to 1.6 percent greater collection, 

it doesn't mean much until you tell us like you did orally, 

that you're netting up to 99.4 percent total collection, 

and then we see the penetration value. We're interested in the 

inpact on the environment. 

MR. SMITH: I see. 

CHAIRMAN LIPPMANN: Penetration would have been an j 

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easier thina to grasp than efficiency. 

MR. SMITH: I'm looking at it from an engineer's 

3 jj point of view rather than what would, be appropriate here, I'm 

sure. 

5 ji DR. EWING: Could I interject at that point? If I 

;understand ir, you would change from 98.1 percent efficiency 

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i jnow to 99.4 percent? 

' MR. SMITH: Yes sir. 

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9 j, DR. EWING: That means however, that the part that 

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10 .is escaping is cut from 1.9 percent down to 0.6 percent which 

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n jj is a three-fold decrease in the amount cf emission. Is that --i 

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1 3 j! MR. SMITH: It would" be a reduction to about one > i ' ! 

14 il third. Just slightly less than one third. j 

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DR. EWING: That's what you're buying with the installation cost and operating cost that you've cited. 

MR.SMITH: Right. Based on the most recent information 

from'the state environmetnal agencies, the current total emissions on a pounds per day basis is around 4,067 pounds per day. 

By applying the controls which we envision, we're talking 

a reduction to 1,317. 

Now, this is not like I say, not considering what 

the regulation might require, it's also assuming that cost is 

no object. It's a technical limit'that could be approached. 

CHAIRMAN LIPPMAN: Just one further question then, 

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• i, a_.t:.ougn you haven't done the modeling yet, the so-called 

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2 '' fence line, would this kind of improvement in a collection 

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3 ;| efficiency reduction and penetration, is that intended to 

i i bring these units into compliance with the current standard 

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5 ' or do better than achieving the current air standard? 

s You must have some idea of whether this much expendii - i 

7 j, ture would enable the smelters to meet the current air quality I 

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o MR.SMITH: It's hard to say because of the nature j 

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-Q j of the emission sources in the computer models. I would say i 

yt ''it would be a mixed answer, in that possibly half of the facili-i 

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.- 7 ties could, make the current standard. I 

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13 | CHAIRMAN LIPPMAN: It would take a three fold reduc-

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,4 'tion assuming that things were that simple, then we would -- j 

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. ii..r.ov.'inc what the current air cualitv levels are, one could I 

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get a first approximation by reducing the levels by three?. 

MR. SMITH: That's an oversimplified approach, 

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•unfortunately. If we were to agree that there would be a linear 

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•relation, the chances would be very good, all accept for one 

of the smelters would comply. 

Realizing that it isn't a linear relation', my own 

personal opinion is, that we would approach the current standard, but I'm not sure that we would ever quite achieve it on a 

consistent basis. 

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!; CHAIRMAN LIPPMANN: Are ther e any othe r questions ? 

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DR. ANGLE: Are all of these smelters in OSHA 

;compliance? 

3 ji -MR. SMITH: Thev're having difficulty in that area. 

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c, j: OSHA requires ultimately that the facility be so designed that 

5 j. no artificial means on the personnel be used for compliance, 

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.5 ;• such as respirators. ! 

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7 |i All of the plants are usina respirators at present, j 

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8 I and. very effectively. But to achieve the requirement by clearly 

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.engineered methods is again, one of the major problems. j 

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This is where the jump from essentiallv $100 million 

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jfor environmental compliance, and then the addition of another • 

j $150 million to meet the OSHA compliance comes in, because ; 

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jit's looking at it from a clearly engineered point of view. j 

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14 j; BR. ANGLE: V7hat is the current range of air values j 

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at the standard air quality, the closest air quality monitoring? 

MR. SMITH: I've seen figures reported in the state 

reports, ranging anywhere as low as 1.2 8 micrograms per cubic 

meter to as high as 5.28. There's considerable variation. 

CHAIRMAN LIPPMANN: Paul? 

DR. HAMMOND: Most of these primary smelters, if not 

all of them, are located in rural areas. That's my impression. 

MR. SMITH: This is correct. The only -- two 

exceptions, partial exceptions. Herculaneum is adjacent to 

a town and the town is essentially richt on the west sice of 

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1 lithe street from'it. And El Paso is uowind from the Citv of 

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3 jl East Helena, Glover and Buick are essentially' in 

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4 !• rural areas. 

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5 i| DR. HAMMOND: Well, that leads to my next question, 

6 ;' as to whether you have any knowledge of the compliance characterij " 

7 !j istics of the secondary smelters, most of which, I believe, j 

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 !: are in close proximity to population density? 

g ji MR. SMITH: I have no information on that. I have '• 

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IQ ,: been working exclusively with primary smelters. 

11 DR. WESOLOWSKI: If you're having trouble meeting 

12 jj the OSHA standard now and aren't allowed to use in the future, ; 

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13 ; respirators, then one of the engineering solutions, is it simply 

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15 l air ? | 

MR. SMITH: Not really. The air flow characteristics 

that one would expect within the smelter buildings, is by nature 

rather unpredictable because of the shape and the location 

of the process equipment. 

And at some of the facilities, the buildings are' 

extremely old and have been added onto several times. And it 

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would be like comparing heating and air conditioning in an I 

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office building that's had several walls added and removed over 

a period of time and it's become very difficult to balance I 

and get uniform flow throughout the building. j 

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The tendency would be to short circuit and get very 

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clean ventilation in one area', very poor ventilation in another, 

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and. by simply increasing the flow rates out of the building 

j to a collector and then to the atmosphere, probably wouldn't 

j result in adequate solution. 

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j In addition to that, you're looking at either having 

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i to recirculate the air back in the cold climates to conserve i 

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! energy or add heating systems to it. 

j CHAIRMAN LIPPMANN: Thank you very much. Let's 1 

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move on to our last presentation on the public side from Dr. , 

i ; ! j Pfeifer of Du Pont. j 

Copies of his remarks have been distributed. ! 

STATEMENT OF DR. CHARLES PFEIFER, Du PONT 

1 DR. PFEIFER: They've been circulated to CASAC 

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by me this morning and I would like to go in the record for 

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this proceeding. 1 

The blue covered, report is our written comments to 

EPA cf March 7th and the other handout is basically a copy of 

the slides I'm going to use in my oral presentation. Our 

comments this morning are going to mainly focus on the results 

of the NHANES II epidemiological study results thatwere discussed somewhat yesterday morning. 

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In particular, we believe that those — that the 

results that are presented in the papers of Harlan et al and 

Pirkle et al, form the backbone of the entire section on 

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cardio vascular risk in the addendum. So we feel as though 

it's pertinent to review some of our findings in some detail 

here. 

4 i Just to review for the Committee and theaudience 

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a little backqround of some ofthe events that have taken place 

'j surrounding this issue. As I just mentioned in '85, two pub- j 

lished papers by Harlan and Pirkle came out which reported j 

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8 jsignificant blood lead blood pressure relationship, and in ourj 

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9 ;i comments on the corrigenda at EPA last year and some ensuing >. 

IQ .discussion at this meeting, Du Pont identified an methodological 

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yi ;: flaw in those analyses, the flaw of being the necessary adjust' 

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12 -j ment for side effects and properly assessing blood lead blood 

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13 ij pressure relationships. 

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And as a result of that, and. other comments that 

were made at that meeting, CASAC recommended the corrigenda 

be relegated to the addendum pending some of the resultions 

of the issues that were raised, and between the last meeting 

with CASAC and this meeting with CASAC, a review process 

ensued that mainly focused on the comments that Du Pont presented 

in writing to EPA. 

And just to highlight some of those correspondences! 

include Dr. Schwartz' response, not to DuPont in the sense 

that he sent it to me, but Dr. Schwartz' response on the 

DuPont analysis, memo of 6-26-85. Dr. Landis, one of the coauthors of the paper presented an analysis. 

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1 Dr. Ware and Dr. Royall on CASAC reviewed those 

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2 '•• analyses. Dr. Royall review was, I guess he indicated that the 

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3 ; results presented by Dr. Schwartz weren't satisfying and didn't 

4 ' answer the questions about which he was most concerned and 

5 another response was prepared by Dr. Schwartz and following that 

5 . v.-as Dr. Royall's final response. • 

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7 j, But that's just a chronology of the main parts of 

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 : the review process that did take place between the meetings. j 

9 Khat I would like to do is just'take a few minutes and go over; 

10 , two slides here that try to illustrate the importance of this 

n j issue that has been raised. 

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12 j For the purposes of illustrating this, what I've 

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13 ' got here are two variables on the vertical access, variable 1 • 

14 j and variable 2 and. the different scales and you can think of ! 

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15 ' those as blood lead and blood pressure, or whatever. And j 

16 j: in the Hanes II survey, what we have is these 64 sites or 

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17 j; PSU's were sequentially visited over the four year period. 

18 • So you can think of at site No". 1, you've got a 

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i mean value for variable 1. At site No. 2, at a later point in 

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i time, you've got a mean value for variable 1, and so forth. 

j • And also you could have the same kind of sets of 

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: out like that, it's very apparent that -- well, we've got 

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„, I; two declining trends and the next cuestion to ask in such a 

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-,_ I: situation is, is one trend for one variable impacting on or 

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i causing the trend in the other variable. Or are thev totall v 

2 unrelated to one another. 

3 | It's certainlv possible that you could have two 

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4 jcoincident trends that have no relationship to one another. j 

5 i'They are just observed to be present over a period of time j 

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fi 1'ior whatever reasons might enter into the assessment as to whv.' 

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7 I Now, in any one case, what I've got here is this j 

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8 jjmicht Pe an individual, of particular individual value, for ' 

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li : 9 variable 1 at sit e 1 and he might be a littl e bit below the I 

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TO mean, but when measured on the other variable, he might be a 

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n j| little bit above its mean. So the individuals within the sites j 

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might vary around the mean in a variety of ways. j 

Well, one could take the collection of these data I 

and plot variable 1 against variable 2. (pause) And here is 

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an illustration of such a plot. ! 

Now, if you could just focus attention for the 

moment on the dots that are plotted there, you could see that 

the collection of all the plotted points of variable 1 against 

variable 2 can, in fact present a relationship that might be 

summarized, by that line. That" kind of relationship in this 

case would be largely the result of what's referred to as 

between site correlation. That is the fact that this cloud is 

here and the mean for another site is over here, and the mean 

for another site is up here, when the data are looked at as 

a whole, one might very well find, a relationship such as that. 

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The important question, however, is what is the relationship when you adjust for site or what is the within 

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i site relationship. There's a cloud of points here for site 1-

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j and a cloud of points here "for site 2 and site 3, and what might 

|be the relationship within those sites. 

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It very veil could be a relationship that is summer-1 

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ized by horizontal lines or essentially no relationship. j 

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1 That's one possibility. ' 

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i It could, be that each of the relationships within j 

j the sites are very much mimic' this overall relationship, i 

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:which would suggest that the between site relationship is the ; 

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same as the within site relationship and the between site ' 

relationship, therefore, is not addinq any potential spurious i 

correlation to the strength of the relationship. | 

The important.point to note is that whatever ' 

relationship exists, should be seen within sites. That is, 

it's the within site relationship that's the only relationship 

that's the only relationship that is of any concern here whatsoever. And. this is particularly a problem with the HANES 

data because the two variables of interest here, blood lead 

and' blood pressure have coincident downward temporal trends 

during the course of the study. 

One may very well be a cause of another, but if 

that's the case, then that relationship should show up within 

sites. So that's the really heart of the issue surrounding 

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the discussions that have taken place in the last year. i 

2 DR. WESOLOWSKI: That wasn't pedagogical data there,' 

3 it wasn't factual data from the — 

DR. PFEIFER: That's right. That's just to make a 

5 point and by looking at this relationship, we could have nega-j 

6 tive relationships here in each case, but an overall positive ' 

7 relationship between sites. There's a whole variety of thingsj 

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8 that could happen, including results where this relationship, I 

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9 you have really no between site relationship, but you do have 

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10 a within site relationship. 

That's also possible. But the important thing to 

note is it's only the within site relationship that's of and 

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concern here and the between site relationship will" be the same 

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thing if it's really there. , 

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Results of the review process that our analyses j 

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and results were not refuted, new analyses of Dr. Schwartz and; 

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Dr. Landis were generally not comparable to the published 

results. They were narrow and selective analyses that only address a portion of all the results in different age, race and 

sex groups that were in the published papers. 

In some cases, there were different model terms 

used. There were different statistical approaches. There were 

a variety of differences that made a fair comparison between 

what was published opposite the issue that we raised very 

difficult to assess. 

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;i The reviewers, Dr. Royall and Dr . Ware, acknowledged 

t he importance of the site issue. In fact, that is no longer 

3 jj an issue. I think everyone agreed, except perhaps Dr . Schwartz, 

• j 

4 I: that sites are appropriate to control for, not onlv Drs. 

i! " " 

5 Royall and Ware but others as well. As I mentioned yesterday, i 

! 

.6 ';Dr. Little and Dr. Bradley assessed this review process i 

7 ij independently and came to thesame conclusion. j 

. | 

8 There were numerous questions that were not answered 

g that were raised in the reviews of Drs . Rovall'and Ware, ques-i 

!| ^ j 

10 ;• tions concerning in some cases an inconsistency of results 

n jj between the analyses of Dr. Schwartz and our analyses for those 

I'

 ! 

12 ;: analyses that were somewhat comparable. 

1 3

 !j Some questions as to what DuPont did in particular j 

jj 

14 '• cases. There were a variety of technical questions that were 

,j 

.jc N raised that they would have liked to have" known, what was the : 

j 

1C ij real situation here that would have helped them better assess 

[i 

.-, jj the results. 

il 

18 jj They responded that the available analyses of Dr. 

j 

Schwartz were consistent with the blood pressure blood lead 19 

20 

21 

22 

23 

24 

25 

association. That is of those analyses that were given, 

he presented adjustment site coefficients for selected groups 

that maintained statistical significance. 

B ut the reviewers acknowledged that the magnitude of 

li ! 

jj the coefficient was drastically reduced in the published papers, 

ij i 

!j whethe r the y were Dr. Schwartz ' analyse s o r DuPont's analyses. ! 

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j 20 

• , What I would like to just show here is a few graphs 

ij 

2 — I hope that shows up all right — they kind of summarize the 

i 

3 results between blood lead, blood pressure coefficients unadiustied 

': ' i 

4 for site and then adjusted, for site. Now, what I've got here, ; 

= just on this horizontal access down here, this just refers to 

.5 the magnitude of the estimated coefficient. 

7 j So this horizontal line is the referenced line of 

8 zero. The groups that I'm looking at in the left side here, 

9 are the various age, race and sex groups that were considered. 

• i 

,0 one vr ay or another in those papers of Harlan and Pirkle. 

n .; The bars that are not shaded here, the blocks that 

12 .are not shaded, represent the coefficients unadjusted for sites 

13

 ! The' shaded bars represent the magnitude of the coefficients i 

-l4 j adjusted for site. ' 

i 

These horizontal lines in here reflect a two ! 15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

.; standard deviation on certain intervals, like a 95 percent 

;confidence interval, and one can interpret statistical signii 

jficance at the L five level, that is if this horizontal line 

il 'i 

intersects this 0 vertical line at judgment of statistical 

significance at the .05 level would be made. 

j • MR. MORGAN: Why are'the length of those bars the 

i same when I treat the data this way, or when I do it in site 

i analyses? It strikes me that the amount of power that I have 

:to get a slope in any one of these, is less than the power I j 

have to get a slope — there are a set of them, so I'm confusjed. 

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. 6 

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19 

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25 

21 

DR. PFEIFER: Allright, there are two reasons for 

jl that. In this particular data set, it'turns out that there is 

ii 

il 

ji very little confounding of, when you insert the site terms in 

ij 

I, the model with the other terms that are already in'the model. 

jj 

Nov.7, the more confounding you have, the more in-

;' flated the standard errors would, be. There is very little 

| 

j confounding. 

ij The other point to make here is that although this 

j. i 

• • craoh was for illustrative purposes, in actual practice if you i 

'1 i 

.j were to plot the HANES data, these clouds are so big and they j 

i l : 

ij are so overlapping with one another, that you don't see this , 

ii I 

!i fine distinction here which would be consistent with your ob- ' 

li • ! 

.j > 

!j servation, thinking it to be more variability, associated with • 

i; ' I 

;: the between site coefficients. Right? The unadjusted coeffi- j 

cients. 

MR. MORGAN: I'll drop it here. But I — 

DR. PFEIFER: Let me just say that if you look at 

-- if this horizontal access was a blood lead access, okay, 

of the total variability in blood lead throughout the entire 

HANES study, 83 percent of it, and that is in the blue report, 

J83 percent of it is person-to-person variability within sites. 

Arid all the rest of it is accounted for inbetween I 

sites, between sites within strata and between strata. So what 

i 

•I'm saving that in actual practice in the HANES data, although 

i •• 

I 

'these average values here across sites are different and 

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ij ''2 2 

i j 

ij 

• :; oresent a colinear trend, the clouds of these points are grossly 

{ i 

2 i-overlapping. And that's the reason for the similarity in these 

ii 

3 j| standard errors. 

jj 

4 I; (Pause) 

li 

5 ,' Well , a fev; points to make here. That the analyses 

. 6 •; that we did were only intended to try to take the results that 

|i 

7 I; were in the published papers, take the models that they arrived 

: i 

8 : at eventually that identified all the terms that were signi9 ficantly related tc blood pressure, take those models of the j 

ii i 

!' I 

10 jj starting point and then we adjusted, those coefficients for siden Ij effects. j 

|| i 

1 2 jj The intent was to try to come up with as fair a ; 

: i ; 

13 II comparison as possible without introducing any other wrinkles j 

14 ;j in the problem that would kind of cloud the issue. So we're : 

ij I 

1C

 j; trying to replicate the analvses of the papers as best we can. | i^*.j-- / - - - -

i i 

16 We did it both unadjusted and adjusted so that what -

17 j ever differences might exist in our analysis from the other 

18 j analyses, we would, be looking at a fair comparison of the 

19 adjusted versus unadjusted situation. And that's wha t is most 

important here. 

If one were to look at the results of the diastolic 

blood pressure on whole , ancfyou're just looking at those re- j 

i 

suits that are shaded in red there, it's pretty apparent that j 

20 

21 

22 

23 

24 

25 

t he adjusted coefficients, that there's no statisticall signii ficant effect. There's not even a consistent pattern in those 

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P.24 

23 

I 

1 ij adjusted coefficients. 

I| 

2 Ij I think Dr. Humprheys yesterday morning raised the 

ij 

3 jj question about what happens to the females in the last three 

I' 

4 jj groups down here , the females, the unadjusted numerical coeffiji 

5 :' ciehts were all positive, but statistically insignificant. 

i 

5 j1 aut when you adjust for them, they "all become numerically 

i.' 

7 jj negative, bu t still statistically insignificant. 

8 l: There's one other peculiarity that I've noted in 

i; 

9 I thes e data tha t ar e somewhat troublesome and I don'tknow what 

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the answer is, if we look at the white males , age group 40-59, ; 

iyou see that numerically'in this set, we have the largest j 

i ~ • 

iblood lead blood pressure coefficient. j 

i 

j There are two groups that were looked, at that were > 

i ' I 

i 

j sort cf straddled this age group. One is white males 56-74, anci 

jthe other is white males 21-55. I 

In both of those cases, the adjusted coefficient 

i 

j is very much near zero and considerably different from the 

j; coefficient down here. Now, that is only a problem or an 

inconsistency of the data as I see it, because in each of these 

models, the age was corrected for — in other words, they not 

only looked at particular age subsets of the data, but age would 

i 

i 

idetermine the model as well. 

I 

j So age is adjusted within those analyses while we 

I 

j; are looking at different age groups at the same time. And 

ij 

iiit' s a littl e bi t troublesome tha t thes e coefficients - - you 

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24 

5 

. 6 

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22 

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24 

25 

woulo thinK tnat the nature of this coefficient woulc De some- ] 

i j 

where between the magnitude of these two. But it's somewhat of • 

I 

i 

an outlver for the diastolic results, at least. j 

'I 

I don't know what tie explanation for that is. j 

i 

Dr. Gartside, I think, last year in public comments to this j 

Committee had mentioned the fragility of the coefficients cf 

the blood lead, blood pressure relationship, depending on what 

i 

sort of age groups you're looking at. j 

ii And there's drastic chances as vou look at different 

|| j 

jjace croups. And maybe this is another indication of that. 

I; 

ji 

jj The other thing that I want to point out here is that 

ll 

I've got the unadjusted results here for comparison purposes 

only. Those results are really not valid results. 

There's no question that these coefficients have to 

be adjusted for sites, because it's very apparent from these 

results that sites, when you're adjusting for site, the magnitude and the strength of those coefficients change dramatically 

They would not change at all if site had no effect. 

But they are changing dramatically. So the unadjusted 

results are not appropriate results to draw any conclusions j 

from. j 

Now, here are the corresponding systolic blood j 

pressure results and those results are a little bit different ! 

than the diastolic. There's more of a consistent pattern, if yo'u 

will for males in the adjusted coefficients. 

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25 i 

1 •; There's still no pattern at all for females in the 

i I 

2 "adjusted coefficients. In our analyses, all of the adjusted 

ij 

0 I i 

i 

coefficients were not statistically different from zero, 

except for the male 12-74 where we've just achieved statistic; 

5 significance. 

.6 . In this case, alluding to the comment that I made 

7 7 about this ace group here opposite the white males up here 

8 and the white males over here, the magnitude of this coefficient 

i 

i 

9 does fall somewhere between those two which is more what you j 

.; i 

.! j 

10 ,: would expect to see. i 

:' ' i 

n j; DR. FRANK: When you use the term site, you are really 

12 ^referring to differences iri time, to sequence, is lhat correct? i 

1 3 ij DR. PFEIFER: Yes. I'm referring'to the PSU's in j 

14 -j particular. There were 64 PSU's and although a given site j 

• i • j 

! i 

15 :l may or given area may have been visited, again later on in the j 

; i ! 

Ij . j 

1C '! studv, it was a different PSU. So I'm talking about the 64 ! 

I D I - -

1

 , 

M i 

il i 

17 j| sequential visits that were made across the NHANES study. I 

ii 

18 ij DR. FRANK: What is the span of time involved? 

19 

20 II 

'I 

DR. PFEIFER: Four years. 

Given that the results that are shown here in red 

|| and here in red, were the first set of results that were arrived 

21 

Ij at in performing these analyses, I think most statisticians 

j! 

j would arrive at the conclusion that there's little, if any, 

| evidence, to support the blood pressure blood lead relation25 j!

 Shi ? -

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P.27 

26 

It's weak at best. Maybe there's a little bit of 

an indication in here, and maybe more work and more analyses 

are in order. But on the basis of these results alone, there 

is not a whole lot of support to say that one had the signifij cant bleed lead blood pressure relationship. 

Nov;, ' here is a comparison of the results that the 

reviewers, Dr. Ware and Dr. Royall, focused their attention on 

in comparing the analyses of Dr. Schwartz that were comparablej 

let's say, to the analyses that we did. i 

I 

And the DuPont results here were shown on a previous 

jchart and I've got Dr. Schwartz' results here and here in his 

reanalyses of the data when adjusting for sites as shown'in the 

i 

red. In the case of the diastolic blood pressure, the adjusted 

i 

i 

coefficient, as you can see here, is very non statistically 

significant, if you will.. 

Dr.-Schwartz found that coefficient, although reduced considerably in magnitude, marginally statistically sig- j 

nificant. In this case the same sort of thing happened although 

the coefficients were reduced in magnitude, Dr.Schwartz still 

achieved marginal statistical significance. 

The inconsistency of these results ' here were somewhat troublesome to the reviewers, and I frankly don't know 

i 

all the reasons why there are differences there. And that's j 

something that needs to be looked into if this issue is pur- J 

sued more completely. j 

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P.28 

27 

In this particular case here, Dr. Schwartz chose 

2 an age group of 21-74 which was an age group that was not used 

3 ! in either of the published results of Harlan and Schwartz --

Harlan and. Pirkle and that's why we didn't use that group 

at all. 

5 I don't know what would have turned out had we 

7 j done our analyses ofth e 21-74 age group. So that's one posil 

8 i! sible reason to account for the differences, but there were a 

9 

11 

12 

13 

14 

15 

16 

17 

18 

19 

few other possible reasons. There are differences in the 

10 jj analyses that might account for this, and. the reasons behind 

those differences were of concern to the reviewers and I think 

need to be investigated. 

Our concerns in this process is that the responses 

of Dr. Schwartz and Landis and the reviews were only based upon 

partial information. They didn't look at the broad scope of 

age, race sex group that were considered in the published 

papers, and when you look' at the total picture, we feel that 

the total weight of the evidence is somewhat different than 

focusing in on.one or two isolated cases. 

EPA has interpreted the review incorrectly as we see 

it,- as supporting the results of Harlan and Pirkle. The unadjusted coefficients are wrong. They are not the correct ones 

20 

21 

22 

23 

24 

25 

to use in developing any sort of policy decisions or risk assessj 

ment or anything else as they appear in those published papers] 

i 

The -- again, the CASAC revieweis are in support of j 

i 

i 

j 

EXECUTIVE COURT REPORTERS j 

(301) 565-0064 i 
P.29 

jthat as well as others, so I don't think'there's any question 

2 there. 

ii 

il 

3 j Also the reviewers only addressed "the statistical 

4 isignificance, or near statistical significance of the results 

i! 

5 . and Dr. Schwartz' analysis for the selected groups were at or 

ii 

5 ji maintained statistical significance, even when adjusting for 

li 

li 

7 jj sites. 

|| 

8 ;: There is also the other side of the issue, as to 

9 ji the maqnitud.e of those coefficients and it was discussed yester 

l! ' j 

TO jj day morning that that magnitude does impact on the cardio 

! 

I. 

n j, vascular risk assessment that is part of the addendum as it now 

ii ! 

ji 

12 jl stands. 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

The EPA made no attempt at follow-up to answer'the j 

i * i 

i • 

j questions raised, by the reviewers, questions that could have ! 

been answered, some of them could have been answered very | 

quickly with a- phone call. The EPA and reviewers have taken the 

point of view that the burden of proof as I'm demonstrating, no 

association. 

Tables 1 and 2 are just the tables that give the 

numerical results of the first two graphs that I've showed. 

That is those published papers purport to show that there is 

a significant blood lead blood pressure relationship. 

Given that those results are wrong, one is not in 

the mode, as I see it, in trying to dispell a significant 

relationship, the burden of proof is not on dispelling it. 

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TISb 

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29 

The burden of proof is on demonstrating it. 

So focusing on those two papers alone, it seems to 

me that the present state of understanding of whether there 

is a significant relationship or not, remains to be an open 

j. question. We've got some pretty strong results here that indi-, 

j 1 ( 

Ij 

cate that there is no relationship, at least among the 

i 

HANES data as we"see it. J 

More analyses have to be done, I think, to fully 

resolve that question though. The cardiovascular risk assess-I 

! 

i 

ment ^resumes causal effect of lead and based on incorrect estij: • | 

!; mates. I already said that. The relationship has not even ; 

I i 

; I 

I been established as yet. • 

| • ! 

j The final thing here that distressed me to some j 

i i 

extent was that we were not even included in tnis review pro- I 

j 

cess, and without a doubt, the review process would have been | 

far more productive had we been involved in the review and 

given the chance to answer questions of the reviewers and get 

to the heart of the issue. 

As I see it right now, I don't know as if anymore 

is understood about the blood lead, blood pressure relationship 

tod-ay than it was 10 months ago at the last CASAC meeting. 

There were a variety of technical issues that were raised in 

the reviewer's comments. 

I'll be happy to answer any questions afterwards. 

I don't really want to get into a lot of detail on that unless 

EXECUTIVE COURT REPORTERS 

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P.31 

ll 3 0 , 

I; j 

1 : vou want me to. But there's one thing that I do want to Point 

11 

2 i cut here is that this use of sites in adjustment of blood, lead, 

I j 

blood pressure coefficient, I said before that if a relationship is there, it should be present when adjusting for sites. 

And Table 4 in the handout, I racked up the results 

. 6 

7 

8 

9 

10 

11 

12 

13 

14 

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21 

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24 

25 

I 

of two blood, pressure correlates that from what I've read in the 

literature, apparently are well-established correlates, age j 

and body mass index. And these are taken from the analyses j 

that the blood, pressure, blood lead results were based upon and 

j 

shown earlier. 

And. I think what you're seeing here is remarkable j 

consistency, whether you're adjusting for sites or you're not 

I 

adjusting for sites, in a variety of age, race and sex groups ; 

i 

in these coefficients. Thev remain remarkably the same. . 

j 

Sites has little, if any, effect whatsoever on those coeffic- j 

i 

ients, as would be expected to be the case if you truly got a j 

_. _. . 

i 

strong correlate with blood pressure. j 

i 

i 

Let me wrap up then with just a few conclusions. ; 

A consistent robust and. statistically signfiicant blood lead 

blood pressure relationship has not been established. 

It's clear from the review process and. independent 

reviews by statisticians Dr. Little and Dr.Bradley that the 

coeffiicents unadjusted for site are wrong coefficients. The 

i 

cardiovascular risk analysis that is now presented in the addendum is without basis. They are using the wrong coefficients. ; 

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P.32 

31 

There are a variety of other concerns that have been 

2 documented with respect to other issues associated with that I 

3 particular risk analysis, but I'm just focusing here on the co-jefficient part of it. j 

i There is no basis in the addendum for inclusion j 

I 

of any reference to the Harlan et al and Pirkle et al, as I see 

i 

7 it. Those results are misleading unless properly qualified. j 

8 The practical impact o'f changes on blood pressure 

9 j| due to blood lead, chances, when assuming causality, are exceed^ 

li " | 

10 ii ingly small. Exceedingly small numerically. I'm not in a position to judge the medical or the practical effect, but let me j 

just "defer to Table 3 which is also in the handout to give one , 

an idea of what we're talking about with respect to the magni- \ 

tude of the change in blood pressure for a given "change in blood 

i 

lead. | 

i 

What I've get'here is a number of scenarios and here 

a variety of values of the blood pressure log blood lead coefficient that cover the _ange of values that have been shown in the i 

literature. Over here, we've got — suppose one starts out with 

a blood lead value of 15 micrograms per deciliter and that 

blood lead value drops X micrograms? Suppose it drops 5 micrograms? In other words, it goes down to 10. j 

If we're using a coefficient of 2, let's say, the 

impact on blood pressure is .81 milimeters of mercury. j 

That's the size of the numerical effect that we're dealing with 

11 

12 

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15 

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- T 

!•; i ' 

ii • j 

•, " here. And you can look over the table as well as I can and i 

I I 

2

 ; you can assess the relative importance of that. 

3

 ! It appears to me that these numbers are pretty small, j 

4 especially when there's so much uncertainty surrounding the 

i 

5 stability of the coefficient in the first place. But for the j 

c ranee That has been talked about here, it seems to me that a i 

j 

- 5 microgram per deciliter drop of blood lead from either 15 j 

i 

5 or frcm a starting point of 20, produces a drop in blood -

o pressure of something on the order of 1 milimeter of mercury. 

i 

DR. ROWE: Which model are those? , 

i 

DR. PFEIFER: This is only based upon the coefficient, 

it's the relationship that blood, pressure equals the coefficient 

' • i 

! 

times loc blood lead. Then the final statement is that CASAC 

10 

11 

12 

13 

14 

15 

16 

17 

18 

I 

must determine the scientific value cf the entire discussion j 

of lead effects, the cardiovascular function that's presently j 

I 

; in the addendum, without solid support from the reported results 

I of Harlan and. Pirkle. ! 

That question begs the point, is how critical are 

Q those results of Harlan and Pirkle in our present state of know-

•ledge? The way I see it right now, there is no support from 

.those papers without at least additional work to try to recon21 : • -

:cile some of the differences and some of the reasons for the 

22 

fraqilitv in these coefficients, depending uoon how you analyze 

23

 : 

the data, depending on what terms vou include in the model and ; 

24 - I 

i 

i 

so on and so forth. Thank vou for vour time. ! 

25 - i 

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1 .. QUESTIONS AND REMARKS 

i 

i 

2 MR. NOLL: I beat up on Dr. Schwartz yesterday. 

3 ii Tccay can I beat up on you a little bit? You said two things 

jl 

4 !: that I would like to quarrel with. 

5 ' "The first is that the results show that site has 

6 V n effect. And the second is that the instability of the co7 j; ef f icients, that necessarily undermines the idea of the causal 

8 ', relationship. 

a And it seems to me that both of those conclusions 

10 

ii 

12 

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'acain flow from exactly the same point I was making yesterday, : 

j which is the implicit presupposition of independence which is \ 

ji i 

I'not true. We know there's a strong correlation between site j 

! ! • 

i; and lead. And consequently, the estimates of the coefficient, 

j ; 

V-"hen ycu have both variables in the model, is going to be unil I 

l; Giased but inefficient, and the calculated standard deviations j 

of the coefficient are going to be overestimates of the true 

jstandard deviation. 

i 

i 

j We know that hypothesis tests of the kind you performed in a model in v.'hich the independent variables are highly 

correlated are not going to be particularly illuminating. And 

moreover, it seems to me that I'm sure that you just sort of 

misspoke. 

You don't really believe that moving from Dubuque 

to Keokok per se is the cause of the difference in mean blood 

^'pressure. It has to do with something else. 

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P..35 

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It has to do with the --

DR. PFEIFER: I'm not saying that at all. I'm say-I 

ing that that kind of move can add spurious correlation into 

the -- results. 

i 

j 

MR. NOLL: But it isn't really the site that's caus4 

inc. It's something else that's immeasurable. Site is an 

instrument for other variables. j 

i 

j 

DR. PFEIFER: That's right. Putting site effects ; 

15 

16 

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19 

20 

21 

22 

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24 

25 

in the model is onlv addressinq whatever differences exist

 ; 

I 

I between sites. So they can be time related or anything else. 

i j 

1 MR. NOLL: Right. But the core point is as follows: i 

•and that is that'there are these unmeasured variables out there 

i . I 

i i 

|for which site is an instrument. Essential core question, it j 

I ' ! 

4 J seem.s to me, is whether there is interaction effect between 

those variables and among themselves or between any one of them 

and lead. 

If indeed, there is interaction effect, that's --

then it's even a worse problem because any attempt to parcel 

out the blood pressure effect among these independent variables 

will be inherently impossible. In other words, the existence oi' 

interaction effects makes it impossible to proceed statistically solely on the basis of individual coefficient estiamtes 

as the indicator of what the true causal relationship is. 

What strikes me is that just like I said yesterday, j 

the basic modeling strategy here of testing specific coefficients 

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P.36 

I 

of•c specific variables'in a multi-variant regression, is just j 

j 

wrong. It's just not the right method. j 

DR. PFEIFER: I don't know where to start but let me| 

4 take a crack at some of it. First of all, you're starting from' 

I , 5 jj the presumption that there's a lot of correlation among the I 

j i 

I

 : 

5 jvariables that have been considered here in these analyses. 

i i 

7 i That has also been expressed, by a variety of other people . I 

7 , . .. . _ | 

8 I including, I think, it is even in the paper by Harlan et al. 

9 II And if indeed there is a high degree of correlation ' 

|i 

10 j| among the predicter variables including sites, then what you 

i! 

11 

12 

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25 

say is very true and it makes the interpretation of the results 

of multi-variable regression procedure very difficult indeed. 

But you're speaking to the quality of the data themselves. 

And if the quality of the data do not lend themselves to properly separating out these effects, then it's I 

i i 

going to be very difficult indeed to do any analysis to separate 

them out. Now, let me come back to your -- i 

MR. NOLL: It's not a data problem. 

DR. PFEIFER: Oh, yes it is. 

MR. NOLL: Look, if there's a joint cause, if the 

independent effect of A plus the independent effect of B, are 

just because the way the world works, less than the sum of the 

i 

i 

two, then there is no data solution. It's a modeling solution, j 

There is no -- if it really is true there are causal 

interaction effects among independent variables, we already 

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i '.know -- we already know there's significant correlation among 

2 • the independent variables because that is, in fact, what 

ij 

3 j| tne regression results show by having the coefficients be 

ji 

i! 

4 .: unstable with respect to specification. 

ii 

5 That's what it shows. We know there's correlation. 

5 •, We don't know whether it's causal. We don't know whether --

ii 

7 jj that's the problem. 

8 '•' DR. PFEIFER: I'm not disputing what you're saying, 

9 but we are in a data mode here , and we have got to deal with 

i i 

10 jthe data in an impirical analysis. No impirical analysis 

i ; 

11 j. addresses the causal issue. 

ii 

n il That has to be addressed externallv rather than 

ii 

ij 

13

 :j medically, biologically and so forth concerns. Okay? Let me 

14

 :j come back to this correlation, because I think you're leaving 

' j ij 

1C the wronq imoression. 

ID 

16 

17 

The- correlation among the various predicter variables 

in the model , even when you put side effects in there, is very 

1D !! verv small, much smaller than even I would have believed civen 

10 i -- -" 

19 

20 

21 

22 ii 

the size of this data set and the number of covariants that 

are in there. 

Now, I made some comments from the back "of the room 

I vesterdav addressing this issue. These are what are called 

variance inflation factors and they are statistical measures 

23 ji

 J 

I of the multi-collinearity present. 

24 v ~ 

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j The values of these factors should be one under a 

i 

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i situation where all the data are independent. All the predictor 

2 I variables are independent of one another. 

I 

3 j The degree of multi-colliriearity is measured by how 

i 

j 

much above one those numbers are. Now, we are looking at num- j 

5 jj bers . comparing the regressions that were shown earlier without 

i i 

i - i 

site effects and with site effects for four key variables, i 

7 ' blood lead included. 

8 i. The impact of putting site terms in there has very 

9 

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: very small confounding impact on any of the other variables. j 

l j 

I MR. NOLL: All that savs is that the interdependence 

i .. _ . 

j that exists is between lead and site. First of all, -- • 

i

 l 

j ! 

• DR. PFEIFER: No, it does not say that. That's the I 

! wrong conclusion. j 

j . | 

j MR. NOLL: The right way to present this information 

is to present the whole covariance matrix. Not to present this 

I 

in single statistics. j 

I mean, I --

DR. PFEIFER: This is a statistic from the whole 

variance, covariance matrix. 

MR. NOLL: But what one would like to see is the 

whole covariance matrix. But the point I'm making is not inconsistent with what you're saying. 

What it says is, we know that there'is -- what 

you have demonstrated convincingly is that there's a strong 

correlation between the site and the lead. That's what you've 

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cemonsT-rateo:. j 

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j 

DR.PFEIFER: I think we're maybe using the term I 

correlation in different ways and that's where our problem is 

M.R. NOLL: It' s not -- j 

i 

DR. PFEIFER: What I have demonstrated is, that the! 

i 

between site relationship impacts greatly on the resulting j 

j blood pressure, blood lead relationship. j 

MR. NOLL: If you were to run a regression which was| 

! 

to predict a person's lead content of blood, with the independent variable being the sites, you would find that you would be 

able to predict it with — the F test on that equation would 

say that the equation explained something. 

It would be that the equation itself "had statistical 

I 

explanatory powers. That's really what you're showinct. 

If you were to run that regression, you would find • 

i 

i 

that vou could predict lead in blood beyond the level of ; 

I 

randomness by simply running a regressionon the 64 site | 

dummy, or 63 plus an intercept. 

DR. PFEIFER: Sure. 

MR. NOLL: All right, and that's what causes the 

problem. That — then the next step has to be to figure out 

why causally that's so, and it could be because the lead co- j 

efficient in a regression without the sites, is picking up j 

site-specific effects other than lead, or it could be that 

the non-linearity in the relationship between blood pressure 

EXECUTIVE COURT REPORTERS 

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i 

i 

1 

i 

2 j 

3J 1 

4 1 

• " 3 9 , ' 

| 

lead is causing the site variables to express part of that j 

i 

non-linearity and therefore, destroy the linear coefficient on ' 

lead, in the blood pressure equation. 

And. either one of those is equally plausible and with -

5 cu~ any further'information. You're absolutely right, in order j 

i 

i 

_& 'to decide which of those two is true, you have to have some sort 

• i . I 

7 ;jcf idea about causality, and you can't prove causality one way j 

ii • 

8 V r the other. 

o i. Ycu don't know whether the reason that the site 

ji 

^variables destroy the lead coefficient in the regression is beIj 

:; cause of the non-linearity effect, the interaction effect or 

ii 

^because the site is in fact, the true cause and lead isn't. 

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lit could, beany of those and it's all equallv likely without 

i _• _. _. 

ii 

iv , . _, ' 

•'-urther information. 

i 

DR. PFEIFER: Your point is well taken. There I 

i 

i 

could be some reasons in here as to why that occurs. But it j 

i l 

Ijalso could, be the case that whatever the reasons for difference's 

| ' | 

jbetween lead, they could be mainly summarized just by the fact j 

that these measurements were taken sequentially over time. 

My judgment is that the kinds of explanations that 

they're looking for, that I think are appropriate to investijjcate by the way, I'm not denying that, are going to have very 

ij" 

i r.ir.or effects on the coefficient if any at all. And the big 

;j 

I! effect is just the sequential nature of the sampling. 

ii 

i! 

ij M.R. MORGAN: What's tha t judgment base d on? 

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DR. PFEIFER: My impirical experience, in dealing j 

.with these kinds of large data sets. When you see such a j 

i 

[dramatic temporal trend in both variables that you're correiaI 

itinc here, le t me just turn the clock back. i j 

j When I read those papers for the very first time, a 

j 

jlittle over a year aqo, I looked through there and I tried to 

i 

i i 

jfind where they have accounted, for the'temporal trend. In the 

j 

iKarlan paper, they alluded to it as a problem and looked at it 

il 

|lin four individual vear groups. 

ij I said well, as a first step, i'm just going to see 

ii 

jjif there's a blood pressure trend. I already know that there's , 

iiblood lead trend in the data, and there was. : 

i ' 

jj 

jl And with that then, I went into the analysis to see i 

how much when adjusting for sites, changes that coefficient. 

And it changed, it dramatically. 

MR. NOLL: On the table you showed us regarding the 

result for systolic blood pressure, the -- one of the things 

that isn't done is the test of the hypothesis that accounting 

for the sites, statistically significantly changes the value of 

the coefficient which is a different hypothesis test than wheth 

they're different from zero. 

Unfortunately, you can't tell from eyeballing, what 

that test is, because it requires taking a count of covariance j 

j 

terms. But my rough order guess would be whereas the corrected 

i 

coefficients are usuallv not statisticallv sianificantlv | 

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different from zero, they're also not statistically significantly 

different from what they were before the -- in the other esti-j 

j 

mate. 

It would be nice to know what the facts were in that 

5

 :j case and the second point is, I'm intrigued by the fact that i 

ii " I 

li 

• 6 Ij ~~ what corrections were undertaken or what attempts were made j 

7 to correct .for the fact that the T statistic in an equation j 

8 j v/ith multi-collinearity is inefficient to begin v/ith. 

9 ji DR. PFEIFER: All rioht, let me address the first l 

" I ii 

10 jj question. The hypothesis that the change in the coefficient 

n jvalue from unadjusted to adjusted, was certainly not done. j 

ii ! 

12 j| Certainly, there are statistical techniques that could do that. 

13 I 

14 I 

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My point of view is it's irrelevant. It doesn't I 

make any difference. Unadjusted coefficients are not of any , 

value. They are not useful. They are just numbers. I 

i 

We've demonstrated, here that by adjusting for sites,1 

you are dramatically changing the coefficients. That's the only 

j 

thing that is important right now, as a first step until further 

analyses are done to try to address some of the causal --

MR. NOLL: I would say that the issue, did they 

i I 

dramatically change the coefficient is something that's susceptible to statistical test. You assert they dramatically change 

them, but the way to back up that assertion is to show that • 

they were in fact, statistically significantly different from j 

jeach other. 

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. . ] , 

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4 ... . 

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i I 

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DR. PFEIFER: Doinc that presumes that there's some ! 

i 

va_ue m the unadjusted coefficients to begin with. i 

; ; 

; 1 

MR. NOLL: No. • i 

i | 

! I 

i ; 

.DR. PFEIFER: Yes, it does. j 

; j 

MR.NOLL: You have asserted that they're different • 

frcm each other. That is statistical hypothesis which you fail 

"CO LSSL . i 

DR. PFEIFER: We can certainly do that. I have not 

• cone that as you can see. All that I tried to do is to look 

! j 

j ar the published results and. try to do those analyses as

 ; 

: closely as possible so we can compare apples to apples, but 

i '• 

1 adjust to sites. ; 

j1 • i 

1 ME,. NOLL: I think we've probably exhausted the issues 

* • i 

, u. n ^. -

 T-' o c n a o.. 

CHAIRMAN LIPPMANN: Are there any other members of | 

the panel that have questions for Dr. Pfeifer? '! 

I 

DR. HUMPHREYS: It does look as if there isn't very 

much overlap in the competence interval for the males and females in something -- in several cases. (pause) 

CHAIRMAN LIPPMAN: Dr. Schwartz, a short comment? 

DR. SCHWARTZ: Yes, I have a comment. First of all, 

in response to your question about site predicting blood lead,j 

i 

that's something that -- but gasoline lead which also has j 

time trend durinc the period, happens to be the same time trend 

" j 

as blood lead, has an F value of about 122 on predicted blood j 

l 1 

1 

I 

EXECUTIVE COURT REPORTERS j 

(i.l) 565-0064 j 
P.44 

43 i 

j 

:• lead. But when you, put 64 sites into the equation, 64 pseudo- j 

2 sampling which are not sites, which did not do in their rejected 

j 

3 ' analysis of the cas lead blood lead issue, tii at explains what 

- gasoline lead did if you took out all of the time trends. I 

i 

5 And. sq I haven't done that testing yet on those 

5 sites and it will be something on the order of 120. My basic 

-, point is that there is a difference between site and time. i 

i 

c I think it's a very important question to say, -look

 : 

9 within site and. see whether you got the same coefficient 

.' i 

•iG and Z shewed stuff yesterday where using more precise measures 

y of site, actually going out and seeking out the urban areas, 

12 then pseudosampling unit, there was very little chanqe in the 

13 'coefficient . In fact in the most precise one where I had 64 

i 

14 urban areas plus a bunch of rural areas, the coefficient went j 

I i 

:up a little. j 

l6 •' What's going on here is that pseudosampling is a 

j 

1? ;very good proxy for time if there are 64 of them. Now, the 

1J: j time structure of the NHANES, again, which -- a long time ago 

jj 

19 but you didn't get the opportunity to see, is there is about 

'i 

:l 

a 40 percent drop in blood lead over the four year period. 

T he drop had the following moderately complex 

contact — which is that there v/as an even variation super20 I 

i 

21 '' 

22 ; 

' I 

„„ imposed on top of a trend has a distinct kink at a place where \ 

23 ^ i 

i 

'there is a reculatorv chance in the gasoline lead. I 

„ New, the tests that I did to look at time and blood ! 

25 i 

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lead, biocd pressure, showed that when you tried to test the 

significant difference in the blood lead, blood pressure coefficient, between those two periods, there was nc -- .75. 

That is to say when the drop in blood, lead accelerated the 

I drop in blood pressure accelerated. , 

i i 

I Similarly, and this is in the published stuff from 

| the -- analysis and. from our paper — , when you looked at j 

' seasons, seasons are statistically insignificant when lead is 

in the picture. So what we have'is, indeed after you control 

I 

for site, not much effect in the coefficient of lead, but 

, because there's a large variation in lead both across the four, 

year period and seasonally within it, and since that coefficient is correlated, with blood pressure, if you take away all • 

of that content, you will be impacting the efficiency of 

i 

estimating the blood pressure relationship. j 

But of course, precisely what CASAC wants to know ist 

i blood lead goes down, will blood pressure go dov/n and that's j 

j 

precisely what the tim.e series stuff shows you. And I do not j 

agree that one should take tim.e out of all these things, that 

that's completely irrelevant. 

There is lots of time series data that's not. 

You want to make sure that there's not some other covariant j 

i 

i 

that was changing over time, and the stuff I provided, I showed 

that in the health examination survey in the '60's and in the

 : 

Framingham study in the '50's, blood pressure was almost . 

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HD I 

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identical to mean blood, pressure in HANES II. It was only in j 

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HANES II where this trend started downward, and the stuff "I

 j 

i 

did looking at the detailed time structure and showing it was. i 

not just a general time trend, but the fact that blood lead ' 

|, and blood pressure varied very well over a complex time pressure 

il " i 

li . ! 

|i that I think is pretty convincing that what's going cn is two I 

H - i 

ll 

j coincident time frames that are so detailed and coincident with 

i 

j each other, that that indeed indicates that one is likely and 

ji 

ji that's all ycu can ever say in epidemiology, to be a causal 

jj 

i' related to the other. 

I 

i And the use of pseudosampling does not indicate site 

j i 

|effects. It indicates time which should not be removed. 

! 

j CHAIRMAN LIPPMAN: Thank you Joe. I think you j 

i * | 

ihave reemphasized the points you're making yesterday and in j 

I * | 

j previous meetings and. I think this Committee has some idea now! 

i 

i j 

j of what the issues are and. we appreciate DuPont's analysis and j 

| j 

j the others which have raised these questions and the responsesj 

in the discussion. 

i 

I would, like, if I could, to invite Dr. Grant and j 

I 

Jordan back to the table to consider with the Committee what | 

I 

implications of all this are and the use.of this data. j 

I 

Thank you very much. j 

i 

We had a proposal vesterday from Dr. Ware. I don'tj 

I 

know if it's a proposal, but he raised, a possibility at least,} 

that some further analysis might be beneficial if the planning! 

j 

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(iCl) 565-..64 j 
P.47 

j 46 

1 i of the analysis were done with all this input and so it wasn't 

a matter of disagreement between data sets based on some dif-

! • 

Ij 

3 jj ferent assumptions and different model perameters which is 

|i 

4 |: part of our difficultv in reconciling this. 

II ' 

i; 

5 j Is EPA prepared to go that one step further to ' 

• i 

\ i 

5 j; resolve the technical uncertainties that have come out of these 

r 

7 j. discussions? 

DR. GRANT: Well, let me just note a couple of things 

that leave us in a bit of a difficult position. j 

! I 

i 

, First of all, I think I do need to respond to points 

j made here that essentially said, that we ignored or excluded j 

DuPont from participating in the review or whatever. Quite j 

i 

i; j 

I' clearly, this issue was discussed very openly here at the last' 

ii ' I 

jj meeting, and DuPont certainly had the opportunity at that time 

li to provide input and they did. 

We had a quite extensive change of information and 

the comments from them that were in the public record and so 

"2 

•3 

*5 

16 

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*8 

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24 

25 

on, even prior to that meeting. We did provide all of the 

comm.unications as noted there to Dr. Royall and Dr. Ware who 

were designated as the individuals here on the Committee to 

help sort this out further. 

And I thought we had. made it pretty clear that in 

terms of ECAO's role in this process that we were available to 

jhelp facilitate and would assist in an oral exchange of informa 

i i 

tion and so on, and we assumed that"if "further information wasj 

i 

i 

j 

i 

EXECUTIVE COURT REPORTERS j 

(30!) 565-0064 j 
P.48 

| 

1 needed, that certainly the CASAC reviewers could contact us 

2 reauest our assistance in qettinc that issue information, or 

i 

3 ij that they certainly were quite able to contact Dr. Schwartz 

ii 

Ij 

4 I' or DuPont directlv to cet more information. ; 

ii " i 

ii i 

5 7 And in the public comments, the blue book or whatever, 

•jl ' I 

5 ii that's just been mentioned, in fact, DuPont notes that they j 

I; j 

7 jj after the meeting contacted Dr. Ware or excuse me, Dr. Royall, i 

I. " I 

I ; 

8 j: or spoke with him and indicated, their willingness to provide 

j more information on their analyses, to answer Questions about 

l! " ; 

jj them, clarify what's going on in terms of their analyses. 

j, Eut that they were not contacted later. Our impres- . 

i • 

i 

i sion after all the exchange of communications that were listed 

r. J ; 

i!

 her e i n DuPont's comments o r presentation , was and base d on j 

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ithe last letters from Dr. Ware and Dr. Rovall, our impression j 

: i 

i j 

I was that although some questions remained, that they were satisi i 

i I 

jfied that the Schwartz reanalyses, taking into account the site 

i i 

i j 

i adjustments and so forth, did. demonstrate a significiant asso- I 

i ' 

i 

jciation and so on between blood lead and blood pressure. 

There were still some questions about why are there 

differences between the specific coefficients and so forth 

derived, by DuPont versus Schwartz. But it did not seem to us 

that that represented what seems now to be a major stumbling 

point or whatever. 

We did proceed on the basis of their last letter 

which essentially we read as saying that they were satisfied 

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... 

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1 8 '• 

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• 21 ' 

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23 | 

;

 4S i 

j 

I with even taking site into account, significant associations j 

I i 

: were demonstrated. And we went with that in the addendum. I 

Now, I may have misunderstood what they were indica-f 

.' ting, but let's do go back over and review what I think we've i 

I j 

heard here. First, as far as the results, even after adjust- i 

i 

•ments for site, when these are taken into account in terms of 

i the NHANES data, certainly the ones presented, by Schwartz, i 

there are still significant associations shown at least for 

j 

the adult male group which has been the major focus of this

 ! 

i 1 

i 

discussion and so on. 

i 

'. And. that's at least for any diastolic blood pressure 

j that still is notable after the site adjustments. And I think -. 

; . i 

1 i 

• even the DuPont reanalyses that they did on one of the slides 

: shown there, the second one or whatever, with the bar graphs, ; 

j still shows a pretty sizable coefficient after adjusting for j 

site in their analyses for that group amount. j 

I . j 

j The next point is, what we did not hear anything i 

j about in terms of the DuPont comments here, were any comments: 

on a second major study which ic also highlighted in the addendum. And. that is the study of Pocock et al, using much larger 

jnumbers of subjects, and so forth, were written quite clearly 

i i 

j the Pocock study reports significant statistically significantj 

i | 

1 j 

.associations between blood pressure, blood lead and blood j 

i: pressure and those associations are strongest or stronger whenj 

i 

i 

2 5 j 

j 

j 

thev include adjustments for site. 1 

\ - -a I 

1 

• 

EXECUTIVE COURT REPORTERS j 

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P.50 

Furthermore, the coefficients that come out of those 

j 

analyses when you adjust for site in Pocock, are very much in j 

the ballpark of the analyses or the coefficients that come outj 

'l 

of the anlayses when adjusted for site as reported by Schwartz.' 

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5 j This is noted'in the appendices or the addendum. I noted it 

yesterday in my comments and tried to focus attention very 

stronglv. 

ii 

h 

|l I have not vet heard anv discussion or criticism 

|l 

jl brought forth that ouroorts to undermine or to destrov if vou 

jv/ill, the credibility of the results obtained by Pocock et al. . 

! 

; So let's be clear. Not basing our judgment in the addendum, 

j ; 

j with regard, to'this issue, only on the NHANES data. 

We are also taking into account the second, set of 

i 

j analyses, Pocock et al, which in our view "very substantially,

 ! 

i 

very consistently, comes out when adjusted for site, pretty \ 

much in the same direction of Schwartz' analyses when adjustedj 

i j 

for site. j 

I i 

We also did not hear mentioned here in any of these 

comments, any of the other number of studies. Those by Moreau 

and so forth, several other ones that are mentioned here. 

Yesterday I brought forth and provided to you information that we have yet another study about to appear from 

Harvard which reports significant association and as Jim Warej 

indicated, they are in the same direction as those reported by; 

i 

Schwartz and so forth. 

EXECUTIVE COURT REPORTERS 

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" i i 

I! 50 

So let's be clear on this point. We are not relying 

only on the NHANES data. That is not only the only backbone, 

|i 

3 jshall we say in quote s here . 

ii 

i 

4 i: There are now several different studies, some thi no 

II 

5 j like at least five,'if I can recall correctly, that are pur - j 

£

 : porting the same kind of results, same kind of direction and '' 

f ' \ 

7 'iso forth. And I haven' t heard any attempt or any indication tq> 

ii ! 

11 . . i 

8 ; undermine or call into question the credibility of the analyses 

9 'of all the other studies. I 

li

 ! 

10 ii So we'r e faced wit h a bi t of a difficul t situatio n 

ii . 

ii '• 

y jj here in the sense that we're looking at what we think is a j 

i: ! 

• 2 |: prettv consistent bodv of information that from the epidemiology 

i i " ! 

i. I| literature that has come out within the last few years , that 

14 Ij consistently shows statistically significant association s be - i 

i' ! 

jj tween blood lead and blood, pressure increases. j 

There are arauments , there are points in her e tha t I 

j 

do need to be resolved further. One of them is indeed, what 

are the blood lead levels at which these associations or these 

increases occur, and the magnitude of those increases and all. 

There are variations across these different studies 

in terms of those particular aspects of the findings. But I 

think at this stage, it would be extremely difficult for anyone' 

jto stand up and say that there does not exist a rather substantial body of literature, epidemiology literature that points 

15 

16 | 

j 

i 

17 I 

i 18 

19 

20 

21 

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^ V in the direction that there are associations between blood lead 

2D 

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1 i and blood pressure increases. we very much do appreciate the 

2 i! importance again, as I mentioned yesterday, of trying to get 

3 jj a resolution as to what are the appropriate coefficients that 

4 

i 

5 

might be useful. 

I think that pretty much from what all I have beared 

5 ;• and. the 'kinds of inputs that we have received, both from CASACJ 

I- "" i 

7 jj frem the public comments, from the reanalyses done by Schwartz! 

ji j 

8 ;• and. all, that probably the consensus is sort of closing together 

I . j 

g that one does need to use those coefficients which include | 

i 

j j 

TQ jadjustments for site. 

11 

12 

13 H 

li 

I think that's something that pretty consistently j 

cores out. Perhaps Joel disagrees for some reason and. so forth, 

i 

but overall the various people that I have been listening to, I 

15 

16 

17 

18 

19 

14 :j statisticians and others, I think that comes out. And when you 

i I 

i I 

;do use tnose, you then find a pretty consistent, pretty much j 

j " j 

jin the same ballpark kind of set of coefficients, comparing j 

| j 

ihis stucv with those or his reanalvses with those of Pocock et 

i 

i 

' ai. 

We do "have as far as the matter of causality and 

so forth, I think again in this case, quite a substantial body 

of literature, and experimental literature and toxicology literature that leaves no question at all, that lead can't cause 

increases in blood pressure. It's there. I haven't heard, anyi 

body come in and really dispute that or undermine the credibility 

i 

i or tnose stucies. i 

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Again, we come to a point, what are the levels at 

which lead, can do that, and what is the shape or form of the 

relationship and so forth. And again, there is room for debate 

and so on. There are some indications that we may be dealing 

with indeed, a complex relationship that maybe a U-shaped func4 

tion that is certainly nonlinear from all appearances and so 

i 

on. j 

i 

i 

11 

12 

13 

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But at the very least, if you will put moderate I 

| 

blood, lead levels in the animal studies, something in the 30-40 

I 

10 | or 50 range, at least'in those areas, it's well established, ! 

i 

perhaps at lower levels, we're not sure. | 

j 

Again, we now come to what needs to be done next to; 

try to resolve this further. And I did yesterday raise that 

cuesticn as to just how close we have to get this if — unless 

somebody can bring them forth to me, data or information or 

evidence or whatever, that contradicts what I just outlined, 

I am left with having to say in a revised addendum that the 

association has been demonstrated, an epidemiology level that 

there are rather convicing animal toxicology results that" help 

confirm that. That there are plausible mechanisms that have 

also been outlined. 

Now, how far do we need to go in narrowing down just 

i 

what the appropriate coefficients are from the epidemiology data! 

I 

And I'm not sure how much data we need to get. 

I 

CHAIRMAN LIPPMANN: I think if I can paraphrase whati 

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7 

i j; Les has just told us, he wants us to close on the criteria 

• ! 

2 jj document addendum and leave the remaining uncertainty in Bruce 

3 :; Jordan's ballpark. I 

I: ' j 

4 i: DR. GRANT: No, I didn't mean to imply that. I 

; | 

5 (laughter) I'm willing to go the next step to try to resolve j 

i 

5 it further, if that is truly necessary. I guess where I'm at 

and I did try some alternative theory yesterday and that was, j 

i 

8 for example, to take the available coefficients that come out I 

9 : of Pocock study, for example, the Schwartz study, adjust it ! 

-t0 for site and make use of those coefficients. j 

; i 

y j There is pretty good agreement. j 

i ; 

12 '' CHAIRMAN LIPPMANN: I think we hear your message. 

i 

i] 

13 One brief comment, Dr. Cole is very anxious to say something, j 

,' • i 

:! I 

14 .And then v/e'11 get some Committee discussion. ! 

' I 

MR. LYNAM: I'm Don Lynam. I just heard Les say that 

there was no opposition, no comments negative to the papers 

|l that were sianed in the addendum and I would, sure like to cori 

jrect that statement. 

I think perhaps if Dr. Grant had read our comments 

that we had chosen not to comment verbally at this meeting, but 

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ii i 

j! to submit written comments to EPA which we did., and we had these 

i 

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; comments express mailed, to Dr. Grant's house on Saturday at 

i " • 

i 

I his recuest, so that he would have an opportunity to look at 

I

I " i 

ii . ' 

;: them over the weekend, prior to the CASAC meeting. j 

j| j 

| Nov.?, obviousy he hasn't had time to take a look at j 

j: I 

i-

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EXECUTIVE COURT REPORTERS , 
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T2Sa 

I! 5 4 

il 

ij 

1 7 those comments because I think if he would look and he is 

!| 

2 \ ci'ing Pocock and. that there has been no opposition to what 

; i 

3 jl Pocock says, that may be true. 

li 

n 

4 j Tne thing is, he has not really cited what Pocock 

I. i 

5 says. And we pointed this out twice in our comments and I would 

I I 

i' 

I. -o 

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; like to just read that quote and this is a direct quote from 

i 

ocock "The association is very weak. The study is observational and it is difficult to adjust for all relevant comfounders. 

Therefore, it is premature to conclude that an elevated body 

i 

lead burden has a causal influence on blood, pressure." 

Now, that's from the article itself, Les, and I canj 

not understand why you say that there's.no opposition. I 

DR. GRANT: I did indicate Pocock's conclusions that 

i. • | 

;, he interprets them in the direction or in the manner that you 

i' " I 

i | 

i'just described. And that's a true fact, that he does inter-

 ; 

I 

prety them that way. 

Nevertheless, his papers do show statistically 

significant associations adjusting for site and. those coefficients are in line with what comes out of the NHANES adjustment. 

j for site. 

I ' CHAIRMAN LIPPMANN: I think the Committee has to 

j 

imove on to his discussion. The question I think the Committee 

i 

j 

jshould try to work toward is whether, in fact, what Les has 

'proposed, that is he feels that the addendum is a statement 

ithat has its uncertainties because these data alwavs have their 

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- T , 

DD 

i j. uncertainty. My impression is that we don't, previously with 

I 

2

 ; the children's effects, and. we obviously were not completely 

3 i satisfied. We had all the data we would like to see. 

4 j' But the question is, is the addendum an adequate 

5 statement of the literature and further refinements of the co6 ] efficient probably does relate to the risk assessments that 

i 

7 ,' OAQPS has to do. But is the addendum an adequate statement of 

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: the literature, such that it can be closed on? j 

' i 

i I think Ellen is verv anxious to say something. I 

; i 

i: i 

j DR. SILBERGELD: Well, I think you really said the 

j i 

j. key phrase Mort, v/hich is that we would really like to have ; 

! i 

l. more data. And I would agree with Les, but I think that qiven 

i 

i 

i the data we have, that the addendum is an appropriate expres- • 

i 

•: I 

I- ' 

I sion cf those data. j 

j; 

I; I have to say that I think further torture of the 

i 

j data, v/hich'is what we're verging on, I don't think resolves 

; these issues. It's going to take more data from different 

j 

, studies v/hich will start to accumulate the information on such 

J things as the proper coefficients and how one takes into account 

I "' ' I 

i j 

site. I 

i 

I'm not sure we gain anything by redirecting Les j 

I 

i 

and his staff and Joel to do yet again another data analysis i 

i 

of this same data set. We think it's been incredibly thor- j 

oughly analyzed. 

Appropriate things have been stated about it, and 

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1 '• I T • 

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•what's stated in terms of the state of knowledge richt now is 

j I 

:appropriate. The field, is going to move on and we can make 

j recommiendations for further research, but I don't think we get 

i 

i 

any further by using the same data sets. 

DR. HAMMOND: I'm not quite sure that is true. And 

imv... specifi.c ^ question to Les is whether they have attempted, any 

1 

i 

!segmental analvsis in the search for a threshhold for these 

i 

j 

:effects on any set of data that you have. 

Just to know that there's a relationship, and not to 

i I 

i . i !be clear as to where the interaction basis to be significant, ; 

I i 

i i 

jis not providing us, I guess, with anything that we can trans- | 

• late into regulation or a threshhold. level of acceptable blood; 

i 

,leaded people. 

i 

i 

i 

So I'm only asking you whether you've really taken 

into account the very important aspects that you come to in the 

i 

end of tryingto find the threshhold for things. 

• 

DR. GRANT: Okay, the question is whether my office 

• 

has attempted to carry on analyses or have either other parts 

of the Agency and so on looking for a threshhold. in regard to 

these effects, no. I don't know to what extent Joel may have 

tried, but I'd say — 

DR. SCHWARTZ: Hidden in one of the back paragraphs, 

we mention that we do try to fit functions to blood lead, blooc 

pressure relationships. And we did not find any threshhold 

within that — any lower threshhold within the range of the 

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D / 

1 :. data. There may be an upper threshhold, but we don't have 

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2

 ! people with blood, levels that high as we discussed earlier. 

ji 

3 ii And as I said, vesterdav when we subdivide blood lead 

I ' ' ' 

4 .-ranee under 10, 10-20, greater than 20, the relationship was

 ! 

ll j 

5 ' stronger, both in coefficient size and significant levels for I 

6 -under 10 micrograms. So if there is a threshhold, it's going 

7 7 tc be fairly low. 

8 Now, on the other hand, we have very few people 

9 -whose blood lead levels are under 5, so I'don't want to say 

10 , that anything much is going on below that . But we did do those, 

CHAIRMAN LIPPMANN: Dr. Humphreys? 

DR. HUMPHREYS: I think that Les misstated the pre13 ; sent nature of the data, in that he talked about the relation-, 

li ' I 

14

 ,: ship between lead and hvpertension as if it existed across j 

![ ^' | 

15 :! both sexes. And it looks to me as if there is in several cases 

11 

ii 

12 ll 

:| 

16 statistically significant difference between the regression j 

17 .! weights for males and females and I have seen no attempt on 

18 •! the part of either anyone involved here to analyze this in 

ii 

ig j the slightest degree, and I am bothered by differences in data 

20 

21 

:cr which no one has an explanation. 

DR. GRANT: I didn't hear Les say it applied 

„_ i| tc females. If I gave that impression, I apologize. That is 11 ;i ~ " 

2 3 

2 4 I 

i 

i 

25 | 

net the case. , 

Clearly, what we're talking about here are across 

several studies, significant associations, blood pressure, lead 

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i i in adult men, middle aged men. 

ii 

2 :' CHAIRMAN LIPPMANN: Anybody else on the panel have 

jl 

3 jj a question or comment here? Dr. Noll? 

i jl 

4 :! DR. NOLL: This is a general point or a specific 

il 

5 ,. question. I do have a point about the agenda today. j 

o ; 

li 

.5

 :i CHAIRMAN LIPPMAN: We're trvinc to come to grips : 

il ""-"' , 

7 ':'• with the addendum at the moment. I 

i: j 

5 ' DR. NOLL: I think the problem I have is as follows: 

I. * : 

9 !j I have an internal conflict here. Part 1, it seems to me that • 

il i 

10 J: the state of statistical modeling doesn't really match the 

ll ' I 

n jj theory. I 

12 I mean, it seems to me the right way to approach j 

13

 l; analyzing the data is when — particularly when you know that j 

14 ij there is multiple causes and that thev're correlated, is to i 

i! " ' 

15 Ij work out a theoretical Qualitatively theoretical understanding! 

IS i 

16 of how you think those interactions ought to work and then to 

17 j test that statistically. 

II 

ig : So I would state that I think that if we were at 

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2 3 j 

j 

2 4 i 

i 

25 I 

the beginning of a process, there wouTd be a way to model the 

statistical work better from the standpoint of producing more 

robust tests of whether there is this correlation and if there 

is one, what it's magnitude is. 

On the other hand, from a decision theoretic point 

of view, it strikes me that the value of that information is 

diminimous. I'm not -- it's not clear to me that actually 

i 

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undertaking that modeling effort at this time has any signifi- ' 

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cant payoff, in part because the real variables that underlv i 

j 

the differences, only to PSU, are basically unavailable in the! 

data set, and hence, you're still stuck with doing nothing but' 

j! ' 

5 ;j this silliness on time trends and dummv variables, which are 

i: "" I 

I! 

I 

6 ji just extremely crude instruments for other things. 

|| - i 

7 |j So I doubt that there's much further ' inf ormation to i 

8 '| be gained 'from a decision theoretic point of view. And I guess 

9 ii what that leads to is a conclusion that some sort of statement' 

j; j 

10 ,| somewhere in the addendum about the nature of statistical 

n j'testing as it's proceeded with regard to lead, I think that 

ii ' 

12 il the conclusions are being drawn that basicallv the clinical 

ll 

13 ;j evidence has to be taken into account, that's absolutely corl! 

14 jjrect . j 

ii ' 

Unfortunately, what hints have been derived form i 

t 

that information have basically not, in a very sophisticated j 

j 

way been reflected, in the statistical modeling by anybody. 

i 

18 jAnd I think that's a liability but I don't think it's worth ; 

curing. j 

CHAIRMAN LIPPMANN: Is there anybody on this panel 

who-feels that the addendum subject to cleaning up which Les 

i 

would do anyway, based on comments of this transcript, is not 

i 

I 

acceptable as a statement of tie scientific literature on this 

i 

issue? Tim, did you want to say something? 

•' i 

DR. LARSON: Well, I would probabl y just cavea t what 

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I! 601 

is I 

1 \t vcu just said, but the way it reads is that your summary says i I ! 

2 j thar there's evidence for strong associations. And in fact, 

;l 

3 ,j Pccock results, among others, produce similar conclusions. 

• i 

il 

' I 

4 What we just heard this before this was that the j 

ii ! 

5 associations may be there, but they're not necessarily strong.; 

.5 j DR. HUMPHREYS: They're clearly not strong. 

i ; | 

7 I; DR. LARSON: But that's what it says on page 6, and j 

• i 

8 • in the review of that middle paragraph, it summarizes all -- I 

9 i: DR. HUMPHREYS: There's frequently conflusion between 

jj i 

;. i 

10 i; strength and statistical significance. And the two are not j n |j identical. 

jl 

12 ;j DR. LARSON: By convincing evidence for strong asso-

'i 

13 'ciations, further their results are consistent with similar 

14 '; findings. So that wording is — doesn't seem to be too --

15 1 . DR. GRANT: Just to be sure, strong association in 

16 "•'. regard to the Pirkle Schwartz thing results, not necessarily 

i

! 

i ; 

yj ". profile, but when you say similar, analogous, no t necessarily 

ii 

18 jj in strength. Although with the adjusted sites, they are in the 

19 jj same ballpark as I said, and in that case, if you're using 

• ii 

Ij those, then it's not as strong in the Pirkle Schwartz. 

ij 

21 ji I agree, there needs to be adjustment in this 

j 

-,_ j| terminolooy here. 

ji 

!: DR. LARSON: The other part of that sentence says, 

2 4 || "and possibly down to as low as 7 micrograms per deciliter." 

ii oc ill haven't heard any discussion of that. 

2 5 I] 

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i ij DR. GRANT: Well, jus t t o clarif y v/hv tha t i s there , 

|| 

2 |; the analyses, the NHANES analyses included individuals mainly 

;i 

3 ;| v/ith blood lead below 30, 40, whatever, in that ballpark, and • 

4 j1 as I recall, the lower end of the range was down to 7, with no 

5 .indication of threshhold. 

6 And that's why they are possibly down to that level 

7 jj DR. WESOLOWSKI: Also the 7 is a detection limit 

8 for most laboratories. 

DR. GRANT: About 2 or 3. | 

DR. WESOLOWSKI: Some have a detection limit of 4, 

i ., so you have to be -- that's one thing you might want to correct. , 

i Because you give the impression that the data'is -- j 

". • i 

1 DR. GRANT: CDC, this study, the detection limit was 

•i • i 

i 

7 what, about 2? 

:i

 DR. MAHAFFEY: About 2 or 3 . 

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jl DR. LARSON: Again, tha t wording , what doe s tha t mean? 

ii 

il Does it mean that you're summarizing by saying that this possibly 

ii 

•j is strong association down to that level? It's possibly association down to that level? 

Or it's possibly the same as the same weak associaj tion that you're"dicussing? 

DR. GRANT: Maybe what it needs to say is essentially 

jthat when adjusting the site, there's evidence for an asso-

'l 

i 

j ciation, statistically significant association for data across 

i 

i 

|the range of 7-30, or in that analysis when carried out across 

jthe ranee of 7-30 micrograms per deciliter. 

i 

i 

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CHAIRMAN LIPPMANN: Clarify your wording. I 

I 

i 

DR. GRANT: Yeah, I d.o intend by the way, to take I 

the recommendations and comments of the Committee and for that! 

' I 

I 

matter, the comment really m terms of the need for much more ; 

| 

I detailed clarification of what these findings are and so on, j 

and to bring them into play. 

And the same thing goes for expanding in relation ' 

to the statute discussion as well. And for example, bringing 

into play the vitamin D calcium mechanism as a possible under- . 

lying mechanism for effects on the low stature and other 

sections. 

CHAIRMAN LIPPMANN: Bob, comment? 

DR. FRANK: I just wanted to add that in view of the: 

reservations that have been expressed about the coefficients | 

i 

on the statistics that underly these coefficients, I would suggest that the predicted clinical consequences which are expli- j 

cit in their numbers on the bottom of page 5, are probably not 

warranted. 

DR. GRANT: Yeah, I think that this is an accurate 

statement of what came out of that, but we need to clarify 

and 

CHAIRMAN LIPPMANN: And make it a completely hypothetical case, based solely on those assumptions and state the 

assumptions and that's the only way that that fits. 

I think, unless I hear otherwise, I ask for a 

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" departure from a consensus that we will be able to come to a 

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| letter of closure on the conclusion of the addendum as modified 

.6 

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:j and complete the criteria document process. Is there a conij 

ij sensus among the Committee for that view? 

ij 

II 

;• MR. MORGAN: : Subiect to proper incorporation of the 

i! 

:j letter of Dr. Noll and Dr. Larson. 

il 

li 

'! DR. SILBERGELD: Some of us would like to see 

ii 

jj seme expanded mention, now that we're going to be on the issue 

j' 

' cf hvpertension blood pressure, of the issue of prenatal effects 

I

1 "* " i 

which we feel has been an increase in information again, since: 

ji : 

jj we discussed this last, and very very directly on the issues of j 

|| | 

ji levels of lead since these are not centering on blood leads : 

li • ; 

j'in women in the range of 8-10. 

ll • I 

I! i 

ji And I think some of us feel it is appropriate to add 

, i • 

11 ; 

ij something to the addendum which recocnizes other area of effect. 

i! ~ I 

CHAIRMAN LIPPMANN: Les, any reaction? 

DR. GRANT: To be sure, we are tying in the information merging from the Binder and Needleman work in Boston. 

Also the Cincinnati work and so forth. 

And there's I think, two kinds of effects coming 

out.- One is the effect on the birth weight in 5, which may 

appropriately fit under the stature, whatever growth and stature section. And the other kind of result v/hich is on early

 ! 

neuropsychologic or whatever development in deficits in Bailey' 

-- or whatever. EXECUTIVE COURT REPORTERS 

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64 

That might more appropriately expand or whatever to 

some extent back in the criteria document, the sections that 

j deal with that aspect. And mv inclination would be to do it 

i 

i in that way. i I 

Or we could put them all in here. [ 

i DR. SILBERGELD: My only concern is that by adding

 ; 

! '• 

.' it into chapters of the criteria document, we lose the concept, 

i i 

i 

. that we are now -- you know, we've had this traditional focus • 

i, 

!' 

j on the young child as the population at risk and I think the 

i 

blood pressure data is saying to us, we have to look at the 

adult male. ; 

These other data are saving we better look at blood' 

levels in adult females. 

DR. GRANT: Well, I certainly could create a section 

I 

another section, if you will, or an appropriate thing in this j 

I 

jaddendum, to highlight the fetal effects. 

CHAIRMAN LIPPMANN: I think we beat Les as far into 

the ground as we can. Before -- we'll take a break and come 

back and resume our discussions with OAQPS and try to think 

about the questions we'll be raising, during the break, about 

vhat you're going to do about the use of coefficients in any 

risk estimation, and whether you need, to call for any further i 

analysis of any of the old data or not in order to feel comfort-

. . . I 

able enough coefficients that you will use in your risk assess: 

i 

ments. 

i 

j 

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oreak. 

P.66 

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65 

So let's think about that, and take a 10 minute 

3 (Whereupon, a brief recess was taken.) 

4 CHAIRMAN LIPPMANN: We are runninc a bit later than i 

i 

I 

5 I thcuoht we'd, be, and. we'll resume the "discussion we put aside 

.5 yesterday in interest of time and I've asked Donna to bear with 

7 us and simply go to her concluding slide and to acknowledge 

8 that some of the conclusions haven't been fully discussed* I 

i 

9 But if we as a panel, have any questions about the i 

i 

10 conclusions, we'll take the time to amplify how she got that 

11 way and perhaps pull back those slides which supported, it, if the 

i 

i 

12 questions come up. But we don't want to spend as much time as . 

13 it would take to go through it in the w7ay it was planned, •-

I 

14 considering the time schedule, and also some basic problems j 

j 

that we'll be discussing about the staff paper v/hich render | 

i 

i 

j 

some of this analysis somewhat moot anyway. j 

So with apologies to Donna for not letting her to | 

Ig !ie heri -.iixii thingy , we ask if she could, come to a resolution of the 

discussion. 

MS. SLEDGE: Okay, this is the second to the last 

pag'e'in your handout and it is our overall results for the j 

i 

various analvses that we've done for our exposure modeling. j 

I 

I 

I think I've already touched on some of the sensitivity analyses 

that we have done to evaluate how our blood, lead estimates | 

are influenced by various imput perameters in the uptake model. 

EXECUTIVE COURT REPORTERS 

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66 

The average daily dirt ingestion rate was the perameter that had the most impact on our estimated blood lead. 

We saw that when we doubled the rate, that the blood, lead 

increased, by approximately 65 percent. 

We also looked at another important component of ; 

our exposure model, which is the indoor dust and outdoor soil '• 

dust lead concentrations that children are exposed, to and these 

were also sicnificant imput oerameters influencinc our blood

 ; 

I 

lead estimate.; and we found that the indoor dust lead concent-; 

i 

ration had. a more significant effec. on our estimates than did, 

the outdoor dust lead. j 

And the reason for this is that in our exposure 

i 

modeling, we have a perameter for the number of hours the I 

i I 

child, spends outdoors, and typically a young child spends a • 

I 

greater majority of their time indoors and because our estimates 

j 

are time weighted average reflecting exposure to indoor dust i 

I 

lead, concentrations, this turned out to be the more important j i 

factor influencing our estimated blood, leads. j 

The third most important factor influencing our blood 

lead, estimates was the dietary component, in particular, the 

constitution of canned food lead. And we saw that if we showed 

or modeled no further reduction in the contribution of canned 

solder lead to the dietary intake in a child, that our blood 

leads increased by approximately 35 percent. 

For our base line scenario, we did have one 

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1 7 opportunity to try to validate the model", and that was us inc 

li - -

ii 

ii 

2 ' scr.e data that was collected in Dallas, Texas. 

3 il What we found was that our -- the upper bounds of 

4

 ;j our model predictions, more roughlv aproximated the actual 

ji 

5 'measured data tha t were collected in pre-school aged children 

. 6 

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j in Dallas during the summer of 1982. And an interesting findj 

i ing which we think is explained in part by the fact that our 

exposure model estimates were' based on air quality that we 

were predicting at the geographic centroids in contrast to the 

i 

imeasured blood leads that were collected in Dallas, that represent children living in the most highly impacted area, 

j We found that were were slightly underestimating 

i and that's why our upper bound model predictions that are 

j approximated and. measured blood leads in the pre-school aged . 

i ; 

i l 

j children. And an interesting finding from this is that the 

reference area in Dallas in each of the children sampled, was j 

i 

i 

similar to the point source areas in terms of the socio- i 

economic demographic and traffic peramters, and was different 

j from the point source areas in that the reference area was not 

impacted by a point source emission. 

|j We found that our exposure model "really had a better 

li I 

:i I 

i fit in comparing it to the measured blood leads that were j 

| i 

I collected in the reference area. And I think this suggests, j 

II i 

ii . i i! as we had concluded when we compared our base line estimate to; 

ji the NHANES data, that perhaps our exposure model estimates j 

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i; 6 8 i 

7 i 

ii ! 

1 , that are based on air aualitv predicted at the geographic I 

,. _ _. _ _• -J _ | 

2 '.' centrcic.s more closely represent exposures in a general urban, j 

3 Ij rather than a point source area. I 

4 ! Okay, one of our overall conclusions which is a 

l i 

I . ' 

5 [ point that v;as r.ade several times yesterday, is that we do feel 

c I that oredictinq impacts of children livino in and around the • w i . • • 

II * ; 

7 !: point source area, based on air quality at the geographic j 

ii ; 

8 | centrcic.s, does underestimate the exposures in the children! 

j ' 

g |; that were very near to the point source. ; 

ii i 

j : 

10 ;' And this is because of the fact tha t there's very 

i 

y \- steep grading in air lead concentration v/ith distance and by j 

,7 -basinc cur predictions on air cuality at the geographic cen- ! 

! ' * ; 

13 j trcids, we are not capturing this highly impacted area. i 

i' • 

14 Ij Another important point is that the populations of j 

II I 

children m these highly impacted areas is quite small. We saw' 

that in 198 0 for the two census tracks closest to source 2. [ 

There were only 252 children in one of the census I 

tracks and 161 in the other. So we are talking about a relatively small population of children. 

Tne point at which I stopped yesterday, was showing 

you-our results for our group point block group analysis, 

which is a refinement of our geographic centroid approach 

which attempts to more precisely estimate blood leads based on 

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!j exposures bf children of various ambient air lead concentra24 :; 

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iition s tha t we'v e modeled. 

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And we did see the base line case that when we 

looked at children living with the 1,000 meter radius of the 

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smelter, based on our blood lead estimates v/hich were based on 

air Quality that was predicted at very close distances to the 

source, such as 200-700 meters, the blood leads for these 

children significantly increased over our predictions based 

on the geographic centroid analyses. 

And again, the Dallas validation study seems to 

support this concept that in order to estimate exposure to 

children that live near ooint sources, we really need to look; 

1 

at a finer grain than predicting air quality at the geographic 

centers of census tracks. 

I know without having discussed a lot of this, 

it's hard to jump right to the conclusions, but if anyone has 

any questions or would like me to provide support for our 

conclusions, I'll be happy to do that. 

MS. MAHAFFEY: I'm sorry for the break inbetween, 

because I'm sure we've all lost some of what we may have under' 

stood. Is'it correct to say that the validation of the model in< 

that's been done is dealing with point source where the overwhelming expo'sures = re something other than airborne lead or 

lead that is currently airborne? 

MS. SLEDGE: Okay. The study that we used'to compan 

our baseline model predictions was conducted in Dallas and the 

purpose of that study was to determine the extent of elevated 

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blood, leads in "pre-school aged children living around two 

point source areas. And they looked at areas out to one mile 

for each point source. 

DR. MAHAFFEY: So would it be fair to say that 

some of the questions that were coming up yesterday, concerned 

whether the various models that had been shown, could be validated to fit known data where you have something other than 

a point source, has yet to be demonstrated? 

MS. SLEDGE: Well, I think our comparison of our 

model predictions to the Dallas lead study do show that our 

jmodel based on predicting air quality at geographic centroids, 

i 

does represent better exposures of children living in a genera!. 

urban, rather than a point source area. 

And that's again, because our model is basing, or 

estimating, blood leads based off of ambient lead concentrations 

that are predicted at relatively far distances from the source\ 

in comparison to an actual study that only evaluated the blood 

lead levels in children living near a point source. 

DR. MAHAFFEY: Eut some of the difficulties I was 

having yesterday in understanding something like why the adult 

male blood lead that v/e observed, in NHANES would be so "dramatically higher than your model for general population would 

predict. That kind of validation and that kind of comparison 

v/ouldn't be shown by the children in Dallas. 

MS. SLEDGE: No. I think your question reflected the 

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li 

l! 

1 j| fact that we were making projections into the future. And we 

i 

j 

2 i don't' have the capability of evaluating how well our model 

ji 

3 j| is predicting into the future. We can only compare actual 

j| 

4 jl data'that's been collected in the past. 

i . 

5 ,! DR. MAHAFFETY: Would it be possible to use your 

6 jj model v/ith the information that existed, say on airborne lead 

Ij * ; 

7 .,. dietar y lead, some genera l value for lead in v/ater, and the j 

•i I 

:• i 

8 i blood, lead data for adult males out of NHANES to make a compari9

 ;i son, say, 1976 to 1980? 

li 

10 il MS . SLEDGE: Oh yes. And just that we chose to 

ij j 

y j1 present the analysis that Jeff presented yesterday to represent 

12 

I' a.U e year 199 0. We could have similarly done that for any other 

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13 ;; year period, and we would have used values for the various contributions of lead, exposure that would, be representative 

15 I of that particular'time period. 

DR. MAHAFFEY: I at least would have felt much more 

comfortable with the validations of models, had that type of 

comparison been made first that demonstrated that the model 

could account for various sources of lead. Because I gathered 

that traditionally, this has been a model that has been developed for airborne "pollutants where there were relatively few 

contributions from non-air sources. 

M S . SLEDGE: Well, our model was accounting for 

exposures from all sources of lead. The air quality dispersion, which is the starting point of our whole modeling process, 

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that's representing ambient air lead concentrations.- But we 

then reflect all sources of exposure in the next steps that we 

go through by using the lead uptake model. 

CHAIRMAN LIPPMANN: Tim? 

DR. LARSON: The numbers yesterday that we're 

6 j| discussed by TRC were 15 or 20 percent of the children living 

near these sources, were typically above a certain blood lead 

level. Does your model, in any way, come up with some such 

estimates? Is it consistent with that? 

MS. SLEDGE: We did use our group point analysis 

under one post control scenario which was at the 1.5 standard 

level. And. I can show you" the results of those and we can 

get some feel for — again, these are population mean blood 

leads, but by applying a GSD we could, get some sense of what 

fraction of the individuals in a population of children would 

be above a certain blood lead level. 

DR.LARSON: I'm not asking you to do it now, but 

what I'm saying is that it seems to be an important "number in 

the other --

DR. SILBERGELD:Well, I think it might be worth showing 

quickly. I think once again the issue is how long it can predict a real situation. 

If you keep giving us projections and the fact is 

in the area of lead, we have an extraordinary amount of real 

world data, and what we keep trying to ask you, and I'm not 

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sure we.1 re getting our message through, is "use your models, no 

2 | for projections, but on a real world, situation, then take the 

real data and see how well they compare. I mean v/e have no 

way of knowing whether your projection for 1990 is going to 

be right. 

6 MS. SLEDGE: No, don't think I suggested that 

7 you try to do that or that anyone do that. We have had two 

8 j| opportunities to try to validate our model with real world 

i 

9 idata, the one being NHANES arid the second case being with the 

jl Jj 

10 || Dallas lead study that was conducted in 1S82. 

CHAIRMAN LIPP.MANN: I think that what Dr. Larson has 11 

12 |suggested is that you'try to see whether the data generated by 

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TP.C validates the model, or conflicts with the model or if not, 

to discuss where and why it doesn't because that's also real 

world data. 

And more specifically relates to an important class 

of point source pollutants. 

MS. SLEDGE: I can give one example of what our mode 

will predict in the future under one post control scenario 

level, that being the 1.5 and as I said, these are population 

mean levels so we could have hired GSD and tried to estimate 

what fraction of the population would exceed an individual 

blood level of concern from 15-20. 

CHAIRMAN LIPPMANN:I think that rather'than go try 

to do that now, by the seat of our pants, we suggest that the 

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ii 74 

il 

i ii staff paper discussion in the next draft presen t that kind of 

2 ji analysis to compar e the model predictions or the -- for the 

ii 

3 ii cases presented in terms of data by TRC and see the match be - • 

|i 

4 ' tween model predictions and the data. 

• I1 

5 •; DR. ANGLE: I think maybe more than that, it should 

6 ij include some snecific recommendatio n based on this data which 

ji 

n 

7 ij is eithe r to the placement of the monitorin g site, when you 

8

 :: have a Point source or interpretation of data from the monitbr9 7 m g sites. In effect, the model attempts to account for the 

l| 

10 •- concommitant increases in surface deposition and residual soil 

il 

n

 l\ lead which are not theoretically available or not actually 

|i 

12 j: measured, unde r air quality criteria. 

:j 

13 'j So that the criteria for the air lead have to be 

•I 

i! 

14 '•> modified, or hav e to be interpreted, relative to distance in 

ii 

1C

 ! the radial crid model from the point source. Is that correct? 

15 | 

16 || MS. SLEDGE: I had trouble hearing some of that. 

•:l 

•I 

17 ;j Sorry. We did look at the data that we have in Dallas 

ii 

•i 

18 j DR. ANGLE: Are you sayin g tha t v/ith a poin t source , 

19 

20 

that the acceptable levels of air lead must be lower? 

MS. SLEDGE: We really haven't made any judgments 

„, ; about criven a certain exposure, what the standard, level should 

21 ; - -

ij be . This whol e "discussion has more deal t with'th e methodolog y 2 2 *i 

;i 

23 ;j that w e used. 

i! 

j I can show you the results for one of our post conij 

oc 7 trol scenarios where we predicted the blood leads that would 

/ b ii 

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result from exposures of an ambient air lead concentration at 

the level of the current standard, 1.5. And in those cases, 

some of the most highly impacted children living within a 

few hundred meters of the sources, the mean blood leads that 

j were predicted, would exceed a mean value that applying a GST 

i 

jof"1.42, would give us an individual blood lead greater than 

i 

j 

j15 micrograms per deciliter. 

j 

j CHAIRMAN LIPPMANN: Okay, now I think in the next 

i go around, we'd, like to see the model verification opportunity, 

10 jj provided by the extensive data set from TRC taken advantage of,; 

and that will give us some greater confidence in the validity 

of the model for the point source impact prediction, which is 

really the issue we're coming to. 

Thank you very much. Now, again I ask the indulgence 

of Drs. Wallsten and Whitfield and ask them to come and discuss 

the lead risk assessment in a somewhat reduced time frame than | 

they had originally planned, covering the main points and not 

all the details, if that's possible. 

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STATEMENT OF DRS. WALLSTEIN AND WHITFIELD, 

LEAD RISK ASSESSMENT 

DR. WALLSTEN: We will be as quick as possible. Let 

me request that as we're talking, perhaps you only ask question 

of information regarding what we're presenting. 

Ron and I have divided this presentation up in such 

a way that we did plan to leave some time intermediate, as well 

as at the end, for questions. And it might help a bit if we 

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i adhere .to that 

2 ' There is a handout that I guess Jeff is passing 

3 around v/hich contains all the slides, but unfortunately the 

4 handout is only black and white. Now, this presentation, we're 

5 focusing again only in methodology and we will simply highlight 

the results. 

The full results, as well as complete documentation 

8 are contained in our report, or in our draft report, and 

9 exerots of the results in the staff paper. Now, the purpose of 

-l0 the risk assessment of lead health effects is to develop proby ' ability distributions over fractions of the population at risk, 

12 that would suffer certain well-defined health effects under 

13 alternative standards for lead. 

14 In reality, that can be considered the final goal 

15 

and one might think of an intermediate goal of the risk assess--

_ . ment is to represent the uncertainty regarding 'dose response 

7 . functions for specific health effects. So in fact, I'm going 

i 

18 j to talk about the first part of this and then stop for questions 

19 i|and then Ron will talk about the second part. 

Now, we feel that the risk assessment we've carried 

out is responsive tc the suggestions and recommendations of 

j William Ruckelshaus when he v/as EPA Administrator, and in 

particular, he said he doesn't want magic numbers, but he would 

like to have an idea of how much confidence should'be placed 

in estimates of risk and the risk calculation should be expressed 

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2 5 I, 

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II 

1 i as distributions of estimates. So we have tried to be responI 

2 sive to this request. 

I 

3 It's important to point out that there are two 

| 

i 

4 j sources of uncertainty associated with the health effect. One 

5 is the uncertainty associated with data. This is the uncertainty 

ll 

5 | that's normally handled with statistics. 

I 

7 j And the other is the uncertainty associated with 

I 

8 jj lack of data. Frequenty judgments have to' be made about health 

II i 

9 jeffects for which only indirect data exists and then it is 

i | 

10 j| necessary to extrapolate from this indirect data and there's a 

I 

li I 

y i; good deal of uncertainty involved here that is not handleable i 

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in the usual statistical sense, and where necessary, w;e did try 

i 

i 

to get some grasp on this. | 

I 

Now, OAQPS asked us if we would do risk assessment j 

for three different health effects, elevated EP levels, hemoglobin decrements arid IQ decrement and v/e will tell you a little 

about what we did in each one. Now, with regard to elevated 

EP level, there are very good data, based at least -- now this 

was not our judgment, but based on discussion with our consultants, they told us that they felt the data was complete as 

one could possibly hope for. 

So we did our risk assessment entirely using the 

data. In the case of hemoglobin and IQ decrement, the data are 

quite sparse, and it was necessary to attack the other sources 

of uncertainty which involve uncoding experts subjective 

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i 

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probabilities. Let me discuss the sample of the EP results. 

Now, the complete data come from a study by Piomelli 

et al, that people here know about, and it's based on some 

i 

18 or 19 — observations on some 1,800-1,900 children. 

And. Piomelli derived two dose response functions 

which v/e represent here. These are lines simply drawn to fit 

the points that they have. One for the percentage o'f children 

v/ith EP's above 33 micrograms per deciliter as a function of 

blood lead and the other as an EP as above 53. 

This represents 1 and 2 standard deviations above 

the normal or the base line. Let us just focus on the EP 

j 

equal to 33 for our illustration. I 

This represents the -- these lines represent the ! 

4 || data but of course, there's uncertainty associated with these 

,r ijdata. And simplv makmq use of the data and the number of 

l b ' - .. 

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children at each point, we essentially calculated for each 

blood lead level distributions of population proportion. And 

what we are trying here, the yellow curve isn't exactly accurate. It's been corrected on the handout. It should have the 

hockey stick look that the previous one had. 

What we s=how in this curve is basically the dose 

response function as well as 90 percent credible intervals 

above this dose response function. And what this — the way 

this should be read is that at any given blood lead'level, 

there's a .9 probability with the actual population response 

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i: 

j rate is.within the dashed lines and .05 probability above and 

•.05 probability below. 

j: This is a fairly standard way of looking at seme 

7 of these data. Our analysis was a basian rather than a classii 

cal analysis, but otherwise, it's the way'that most people are 

used to looking at data. 

i 

: 

! And we will be using curves of this sort. 

Subsequently, although based on judgmental probabilities 

rather than subjective probabilities. 

I am hurrying and this is discussed in more detail 

in our report. Let us turn now to hemoglobin detriments. 

We did present some of this at the last CASAC 

meeting. This is really a summary just tovork up to the IQ 

• 

'stuff, to kind of warm you up, so to speak. 

Now, in this case, the data are quite incomplete, 

1 

i 

; and so it was necessary to consult experts to do some subjecti 

i 

live probability coding. Let me first show you what is the 

, semi-bottom line of a probability coding and then I will tell 

| 1 

you how we got it. 

Now, we show here results from the judgments of 

i I 

jthree experts, C, D.and E, regarding lead induced response 

i 

i 

1 rates for hemoglobin, less than equal to 9.5 grams per decii 

jliter among children, ages 0-3. I hasten to point out to you 

i 

1 that the axis are not the same from one graph to another and 

j 

jand we will, in just a slide or two, have a more comparable 

I 

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i .graph. .This is just to give you an illustration of what v/e 

2 7 

3 :| The yellow curve on each of the three panels 

4 represents what we might consider to be each expert's best 

5 judgment about what the dose response function looks like, 

6 based on the analysis we did, given the subjective- probability 

7 jin coding, we would say that at any given response rate, the 

8 expert thought there was a 50 percent chance — sorry -- any 

9 given dose, there was a 50 percent chance that the response 

10 rate was above that line and 50 percent it was below that line.; 

i 

i 

,i The red line showed 90 percent credible intervals | 

i 

:. - I 

12 ,and this is read in exactly the same way as previous curve, 

13 : cf course it was obtained in a different fashion. Now7, let me 

14 ;go back and show you how v/e obtained it. 

15 . Again, we discussed this at the previous CASAC 

16 'meeting so I'm not going to go into a lot of detail, but 

17

 : v/e did visit each expert twice. The first probability includ18 ing the session generally lasted a full day, and we had a good 

: i 

ig 7deal of discussion recarding the literature, structure of the 

|j 

j'problem and so on and so on. 

Ij And when .v/e finally got the individual's probability 

l

; judgments, we did fit the functions to them. We sent all of 

n 

jithis material back to the expert along with a lot of explanai. 

;

:tory material. 

25 I 

We went back a second time and v/e discussed all this 

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1 with them and finally, when we not only had the judgments 

2 well represented in the goodness of fit sense, but the expert 

I; 

M 

3 ijalso agreed that they were well represented we then used the 

h 

4 j! functions that we fit to the expert's judgments. 

!i 

5 : New, be careful in reading this graph. This one 

6

 :I stooped us for 15 minutes at the last CASAC meeting. This is 

j| 

7 j; different from what is normally seen. 

8 '; We have on the X axis response rate. We have on the 

I 

i 

9 .; Y axis a judged probability that the actual response rate is 

jj 

10 -equal to that value or less, and for each curve, we have a 

n |, different blood level. So for example, to look at the red 

12 il curve on the right, L equals 55, that curve represents the 

i | 

13 ij expert's judgments about population response rate at a dose 

ii 

14 jl level of 55 micrograms per deciliter. 

T2Sb 

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So one can read across and get the expert's probability judgment that the response rate is less than or'equal 

to any given value on the X axis. Now, if one imagined a 

|horizontal line drawn from the Y value.of .5 across, that represents the 50 percent judgment. 

And so each point, each curve that's intersected by 

this horizontal line at .5 represents the 50 percent judgment 

that I showed you previously and so on. What I showed you 

previously with the judgments, we fit functions to those judgments as I've showed you. 

Now, we took the 50 percent slice across in these 

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curves and 25 percent slice across in this. And by taking 

those slices across, we created the curves I showed you before" 

i 

| So these can be read in'the same way as say the 

i 

I dose response functions for the- EP along with the confidence 

j 

intervals about what thev were obtained in terms of getting 

5 |; judgments 

jl 

8 7 Prepared another slide which now we think is a reasonably good 

7 |j Now, these are a bit hard to compare, and so we 

9 |i way to look at the range of judgments and uncertainty regarding 

P 

10 lithe lead induced, hemoglobin effects. Now, we have shown in here 

ij 

n li just for the hemoglobin level 9.5 and for children aged 0-3. 

12 

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Each — v/e have experts A, C, D and E, four of our 

five experts, the fifth one declined to provide probability 

judgments, as we described last time and we have shown at each 

lead level, a summary of each expert's judgments. So let's 

take, for example, for a lead level of 35 micrograms per deciliter, do you see that expert A believes that the percentage of 

kids having a lead induced hemoglobin rate less than 9.5 of 0, 

then the other three lines show both the expert's median judgment or the 50 percent judgment as well as 90 percent credible 

intervals above that value. 

So this shows some indication of the range of uncertainty for each expert as well as the level of agreement or 

disagreement of processes. And by and large, one might summar 

ize this by saying that experts C, D arid E have some degree of 

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r. 

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1 ' overlap.in their judgments. Expert A has a difference of opin2 ': ion with them and so on. I won't go into it. 

3 ij But there are a number of curves of this sort that • 

4 summarize the judgments that we got for the various, for the 

5 two levels of hemoglobin and the two papers. Now, this was more 

5 er less a review, although I think a little nicer presentation 

: ~ j 

7 I, than we had last time in terms of the graphics. j 

8 : Let me now turn to IQ decrement which is new. | 

i 

. i 

9 As you are all painfully aware, the data on IQ are controver- I 

i. 

10 sial, and so we could not work directly from the data to get 

i 

n I'judgments about IQ decrements. 

I 

12 !: When we began to develop our protocol for IQ, for 

13 •'encoding judgments about IQ decrement, it became clear early 

il 

14 :. on, it was a much more complicated problem than hemoglobin. 

16 

17 

18 

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._ iThe'IQ's influence or at least from one perspective, it's 

j influenced by long term lead exposure during the course of 

•behavioral in CNS development. At least that's the issue that 

is under "discussion. 

The long term lead exposures confounded with other 

jvariables that effect IQ, and therefore, some it's impossible 

j to observe IQ* decrements in iridividuals and attribute them to 

:sinqle causes. Simolv, it's a much more complicated problem i .... -

jand it required a slightly different protocol. 

In developing the protocol for doing the probability 

encoding, we used 14 consultants. We circulated many drafts 

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for the.protocol, 

We shifted our focus to a hypothetical experiment 

that I will describe momentarily and we did a considerable 

amount of pilot encoding until we finally felt we had the 

5 j problem well structured. Now, in the hypothetical experiment, 

jwe asked our experts to consider, to imagine that a large 

I 

i 

I number of children were randomly assigned to exposure groups. 

i 

j The exposure groups were defined by blood lead 

g j, on the third birthdav. The control group was sheltered from 

Ij 

10 jjlead. The experimental groups were exposed such that the blood 

lead, on the third, birthday was either 5, 15, 25, up through 

55 micrograms per deciliter. And on the seventh birthday, we 

administered the WISC-R to get their IQ source. 

So this was a hypothetical experiment. Now, the 

experts were given the opportunity to consider the experiments 

separately for lower arid higher SCS populations, were lower 

SCS populations defined as the lowest 15 percent of income. 

We did that as to as consistent with the NHANES group as we 

could. 

Five out of our six experts did that. Now, this 

hypothetical experinient has several advantages over what would 

have been the first blush in our straight forward protocol, 

namely the questions that we asked our experts were natural to 

think about. The hypothetical data are similar in form to 

actual data, but without the problems of the covariates. 

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These questions allowed us to calculate certain 

2 important indicators. One was subjective probability distribu3 I tions over dose effect functions, mean IQ decrement as a function of blood lead. 

5 i And the other was a subjective probability distribu6 tions ever dose response functions. A percent of children 

having a lead induced IQ below any particular level. 

We asked our experts to give us probability judgi ; 

9 |i ments "about three perameters, that is three parameters for the | 

P i 

10 | low SES group and three perameters for the high SES group. j 

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One was the mean of what they thought the mean IQ of the control 

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group would be and I'll come back to this in a minute. 

The second is what they felt the within group IQ 

i 

i 

standard deviation would be. And the third is what they feltj 

the mean IO decrement for each of the experimental groups relative to the control group would be. 

And we didn't ask it in this direct fasion. But 

there isn't time to talk of the details of how we did the 

probability encoding. 

Now, one would immediately think, well for points 

1 and 2, why "not just go to the standardized data? Well, we 

do know mean IQ's and we do know standard deviations and so on 

The point is, the standardized data includes kids 

with lead in their system. And we're talking here about 

control groups. 

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ii 

j 

' • .S o we did bring with us to these sessions- the best 

ii 

2 standardized data we could find in stratified according to the 

3 ; suitable variables here, and we asked our experts to consider4 I how these groups would be if only they didn't have the leaded 

=. kids in them. 

6 Now, this is not something we could calculate, and 

7 j again, there is not time to explain why that's true. I can 

8 .• answer any questions. 

i 

9 . But it was up to each expert to take the standardj 

10 j ized data as they were, adjust them as he or she wished to or | 

y j what have you. There was one expert who felt uncomfortable 

j 

12 | doing that, "and thought we should be able to calculate it best 

!3 | as v/e can. 

j; 

14 i So five of the six experts responded to all of the 

,r I1 three Questions and one of them pointed to a third cuestion. 

lb , " 

- jj Here are the people who participated in the encoding, they all 

ID ,; 

7 |i agreed to do it. 

18 v As I said there are six people. Five of the six did 

i9 jgive us probability judgments on all three of those perameters, 

; and one of them on only the third one. There was a good attempt. 

i 

I made to span the rarjge of opinions and judgments regarding the 

j 

jIQ effects of lead. 

j 

I Now, this is a representation, not a particularly 

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'ieasy one to read. And we will come to easier graph in just a 

2 4 ij 

25 |; second . But representatio n of each expert' s probabilit y 

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judgments regarding the mean IQ decrement as a function of 

blood lead. This is really just a representation of the third 

perameter that we encoded. 

Nov/, note in particular here that the ranges, the 

1 

1 

range of numbers on the X and Y axis, are not the same from expert 

to expert. These are not comparable graphs. 

But let's go onto the next one as it's easier to see. 

Here is the same representation v/e had for hemoglobin, looking 

only at the'judgments regarding mean IQ decrements to the lower 

I 

SES population. j 

Again, each point represents the median judgment anc 

the bars around the points represent their 90 percent credible 

'intervals. And you see for example, that there is a -- let me 

turn to my notes for a second here — there is a good deal of 

agreement throughout between experts G, H and J and a good" 

.deal of agreement throughout between experts I and K. 

B ut then by the blood lead level of 25, G, H, I, J 

and K all have overlapping judgments. Expert F considered the 

effects of lead to be much less and that personr s judgments 

begin to drift away from the others. 

Expert F.feels that there really is no effect up 

til 25 or 30 micrograms and then just a very tiny one. So 

• there is really a good deal of overlap in their judgments. 

For example, at blood lead of 25, not focusing on 

expert F, the lowest median judgment is that there's a mean 

jj 

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| . 88 | 

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iIQ decrement of 2 points and the highest is that there's a mean 

iIQ decrement of close to 5 points. So there's roughly a 3 

I 

jpoint difference between the median judgments. This is not 

I " i 

icoming up for five out of the six experts, and so on. 

ii 

5 So there really does appear to be a good deal of 

i' 

5 ii cer.eral agreement, considering the level of uncertaintv. We 

ji ' _ 

7 jj were also, now making use of all three perameters that we asked 

j; 

8 ; the experts about, to calculate subjective probability distfi-

- ' butions over the percentage of kids with lead induced IQ's bel i 

i 

10 jlow any particular level, and for illustration here, we took 

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an IQ of 85 which is base standard deviatio n below normal I 

| This is most analogous to a dose response function. 

1 

! 

iThe other functions we showed, you are analogous to dose effect 

jfunctions. This is analogous to dose response function. 

I 

i 

j And here is the graph that is easy to read, where 

again, you see a good deal of overlap among the implications of 

the judgments of now four of the five experts. One expert, 

expert I did not feel comfortable making the judgments regarding 

the control group and so on, so we couldn't do this calculation 

for that person. 

I think X set a new record. This was originally a 

4 0-minute talk. Let me do the summary. 

Let me make some observations about our methodology 

First, we did make use of statistical and judgmental uncertainty 

as appropriate. We used statistical uncertainty as far as it 

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it would take us and went beyond that with the judgmental uncertainty when necessarv. 

• _<• 

It's fair to claim that the participating experts • 

at least with some practice, and some -- after being in this 

situation £>r a little while, were comfortable with the process 

| It's important to realize that by carrying out thi's probability 

i 

encoding process, we focused on well-defined scientific issues, 

so that when there were judgmental disagreements, they were 

|! attributable to interpretations of evidence and not to differll 

fences or definitions or policy implications or what have,you. 

i i 

j Once we did that, it turns out there really was or 

i 

jis substantial overlap in the judcments, and it's worth point-

| 

jing out that our resulting probability estimates are obtained 

iri a systematic open, and defensible mariner. 

Each experts uncertainties represent itprobabilistiI 

cally. The range of uncertainty across experts is represented 

probabilistically. 

The implications of these uncertainties can be 

explicitly derived and we believe that these representations 

and implications should be useful to analysts and decision 

fmakers in considering maximum allowable blood lead levels. 

i 

i 

Now, this is a suitable place for me to stop to take some questions before v/e try to kind of tie this in with exposure 

analysis. 

So let me stop here and see if anybody has any 

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1 11 Questions. 

2 >\ CHAIRMAN LIPPMANN: Granger? 

3 ij MR. MORGAN: Mr. Chairman, I've been giving advice • 

i ; 

:i 

4 -i tc OAQPS on this general problem area now as a member of three 

5 . different SAB committees or subcommittees. And OAQPS, of 

5 ;| course, knows that many of my comments over the years have 

7 II been highly critical in this area. 

8 ': From everything I can tell from looking at the 

| 

9 7 documents supplied in this briefing, I think this is a first j 

ll I 

10 7 class piece of work. I think OAQPS is to be congratulated j 

7 i 

'• I 

11 ij for having persisted and. done it correctly and well. j 

|j " * i 

1 2 Ij I think it sets an excellent precedence for the 

ri 

:i 

13 'j use of these kinds of techniques. In the future, I would only 

il — 

14 l| urge you strongly as you begin to think about using similar 

15 j technicues in upcoming criteria reviews, that you apply the 

16 same quality of high level judgment on the quality control 

17

 !! that's displayed in this work, 

il 

CHAIRMAN LIPPMANN: Warner has also participated 

for a long time in this development. Do you have any additional 

comments? 

DR*. NORTH: I would like to echo Dr. Morgan's com2, !| ments. I would concur with him completely. 

i 

i 

23 |j I do feel, however, that v/ith respect to the draft 

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24 report on this, there is some polishing that's needed, and I 

25 |! will communicate that directly to the authors, 

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CHAIRMAN LIPPMANN: That's certainly true. Dr. 

Mahaffey? 

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3 || DR. MAHAFFEY: This is not critical of your method, 

li 

It 

4 |; but I think it's important to perhaps bring to your attention 

p 

5 . and the group m general, the data that relates to erythro6 i, cyte propoporphyrin to blood lead, represents one data set. 

7 j| There's another large data set which again is 

3 ;'NHANES. We know "that erythrocyte propoporphyrin is influenced 

g II verv much by iron status, as -well as by lead exposure. II 

10 j, Anc I'm very concerned that by using the data set 

I; 

y jof Piomelli only in which iron status is not measured and not 

I i 

12 I accounted for, that perhaps the kind of conclusions drawn are 

M 

i ; 

13 jj incomplete, not because of your method, but simply because the 

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14 idata sets, we have been working with, is not providing full 

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!,' - - ., ii mrormation . 

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And I don't know whether Dr. Chisolm and Dr. Angle 

or Dr. Hammond might care to also address this topic but 

I will be glad to provide a preprint of the paper as well as 

the NHANES publication in which this is dealt with. 

B ut there's first of all, an'interaction term between iron status, lead exposure and the EP response. And 

definitely in the data sets which you have heard to work with. 

I think your dose response information may not 

really reflect what happens with lead. 

DR. WALLSTEN: If I can say two things in response 

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1 •i to that, Your point there is very well taken, that just the j 

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2 I'-sct that the data set has a large number of observations, I 

3 i: doesn't necessarily mean vou should go v/ith that data set onlv,' 

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i' - - I 

4 '< Tnere are considerations of a sort that you mentioned. 

!' ' ! 

5 , And for better or for worse, we only went to that j 

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6 ; data set after some people told us that they felt there was a I 

i " : 

7 ' good representative data set. But certainly in general, the j 

, i 

I i 

8 I fact that it's a large data set doesn't mean it's a good one j 

i I 

9 ' tc use for this kind of purpose. | 

!

:

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10 j And that if there are factors of a sort that we're . 

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11 j; talking about, then one needs to be concerned with those, since 

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12 j. there are multiple data sets and one could handle them. I j 

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13 || agree with that. j 

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j i 

14 I -.Now, we were aware of a second data set that we : 

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15 •' did not use because of certain statistical nonindependencies 

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within that data set. It looked, crudely as if it was given the 

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' same results, but we couldn't do the same kind of analysis. 

i 

So that point is well taken in general. I agree 

I 

I what that point. The other thing let me just ask, I thought 

j 

that Piomelli and his group had taken out kids who were iron 

deficient. 

DR. MAHAFFEY: The thing that paper states when you 

get into it very carefully, is that they were selected to mini 

mize the number of iron deficient children by looking at 

children who, I think, were at least two years old. As I 

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i . understand that data set, there are no actual measurements 

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2 ;' of iron status. 

i3 jj DR. SILBERGELD: I would just like to register 

4 l again my misgivings about this process. And its use in the 

r i 

5 decision making of OAQPS and EPA. 

6 I. I think that it enshrines a tendency towards con7 jl sensus and majority opinion which is fundamentally opposed to 

8 ! the progress of science. And that by looking towards the 

9 I centraiity of judgments and opinions, about the effects of 

li 

10 '.toxic substances, it tends to discard outlyers which may in j 

j 

fact, in the course of further information and research", turnj 

i 

i 

o ut to be what is the case. And it's iust a "fundamental I 

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13 I; philosophic reservation about this process. I would just like 

14 to register it, 

15 I DR. WALLSTEN: Let me respond to that, since I dis -

| 

|agree with you strongly. But it's only a matter of opinion 

I 

,i jl of course. 

In any case, I would argue that rather than put 

t he scientific research in a secondary position, but to sometimes help to do, is it point out where research is most 

21 needed, by —* especially by looking to see where there are 

outlyers v/ith respect to the majority opinion. 

There's a distinction between having to make a 

policy judgment given available information and deciding where 

do put resources for future scientific research. I don't think 

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the two.should be confused. I think the process is useful for 

2 both, but for the one wants to look at the outlyers and then 

3 question why that person has those judgments. And for the 

other, wants to express as well as possible the weight of the 

5 current judgment. 

5 They are two different but related processes. 

CHAIRMAN LIPPMANN: Thank you. Why don't we move 

8 jj ahead. 

i; 

il 

9 | MR. MORGAN: May I have 3 0 seconds on this, Chairmanf" 

10 jj In the earlier work that OAQPS did exactly what you here exjj 

11 j! pressed and was reflected in that work. Namely, experts were 

I 

12 | essentially averaged across and one got a single composite 

i 

!3 j result . 

14 These results now as presented in this staff paper 

15 are displayed, expert by expert, so one can indeed see both 

16 —

 on e ca n se e t*ie r£n 9e

 of expert opinions. And if there 

17 are people who have clearly very different opinions, they are 

i8 i displayed, I certainly agree that an activity that involve 

19 averaging across experts when experts are not all telling you 

the same thing, is dangerous in this kind of environment. 

21 DR*. WALLSTEN: The plan that we had is that at this 

point, I will sit down and Ron would tell you how we usually 

-._ go in exposure analysis 

24 DR. WHITFIELD: This is where we picked up with 

25 the risk assessment. We used it in focusing encoded judgments 

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and the .published data appropriate to develop functional repre-} 

sentations for dose response relationships. 

We combined that infornation with blood lead distribution information to form the overall risk distributions. 

jThe blood lead distributions came from the exposure analysis 

i 

jthat Donna has so carefully described the last couple of days 

i 

j We have some statements to make about the exposure 

estimates. One and I'm reiterating what Donna just said, 

or would have said if she had a chance to go in all her details, 

one is that the estimated mean -- these are estimated mean 

blood lead levels and their average is over wide areas around 

the point sources. 

Second, these mean blood lead levels are based on 

i 

air quality estimates at geographic centroids. Both of those I 

things, both of those assumptions could lead to underestimating 

the getting -- lead to estimating lower blood lead levels, i.e 

overlooking the most sensitive children close in to the point 

sources. 

EPA is working on refining the analysis group to 

get a better idea of how high those blood leads may indeed be. 

The third point is that the blood lead levels are for 84 month 

cohorts of children. And the fourth point is an assumption on 

our part which seems to be very popular in the literature, one 

of assuming that the blood lead distributions are log normal 

and we used the best estimate for the geometric standard 

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[ 

Here are the mean blood lead values that we used 

1 ;, deviation we could find, that of 1.42 micrograms per- deciliter 

2 

3 j to do the erythrocyte propoporphyrin risk estimates to develop 

4 M them. The models were able to produce blood lead, mean blood 

I! 

5 |, lead, estimates for children aged 0-6. j 

ii i 

i 

6 j; And that most closely matched the ages of the children 

jj i 

7 jl that were in the Piommeli et al study and that's why we used 

li 

8 j; these numbers. What we have here are estimates around two 

9 li point sources, which we label 5 and 2. Five had the best I 

I" I 

10 '; air quality, if you will, and 2 had the worst air quality, andt 5 I 

n |j the other 3 were inbetween. j 

ii ' I 

I ! 

12 I Three scenarios, three groups of scenarios, were j 

jj ' I 

13 |l considered in developing mean blood lead estimates. One was 

14 | the baseline as Donna has discussed and the post control 

period, as Donna also discussed. 

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! 

A third period inbetween was the pre-control period 

For lack of time, we're not focusing on that right now. 

Post control period also considered five alternate 

ambient air quality standards for lead. 

DR. SILBERGELD: In considering the data that have 

been collecte'd around the world, do you seriously think that 

it is conceivable at any point in the foreseeable future that 

blood leads in the United States will be at that level? 

DR. WHITSTEIN: You're referring to the low levels 

out on the right side? 

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DR. SILBERGELD: Yes. I asked my fellow colleagues 

on this Committee whether they think that that's foreseeable. 

Katie, do you? 

DR. ANGLE: It's seems especially unlikely in that 

source too, where you have in ten years you propose complete 

irradication of surface residues. 

DR. WESOLOWSKI: We have to improve our detection 

limit quite a bit, won't we, to get down there? 

DR. SILBERGELD: Well, the thing cf the Nepalese j 

j 

j children were what, 2-4? : 

j 

DR. MAHAFFEY: The thing that concerns me, this take^ 

i 

I 

off from the projections that v/ere given in the earlier presentaf 

tion which I think the consensus of the group is those requirej 

some validation, and to then develop this from that, seems to 

be unrealistic. 

MR. HAINES: I think that -- let me clarify a couple 

of points. I think yesterday we tried to get the point across 

that we ourselves v/ere not satisfied with estimating geographic 

centroids. 

You raised other concerns. I don't think — so we 

know we have "concerns about the air quality projections. Under 

themselves for the purpose of Ron's presentation, I don't 

think they're very significant. 

What he's trying todo is show how you marry these 

two things. We come back with exposure estimates, everybody 

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ij 

i ,; agrees .to, and you think his methodology is appropriate, then 

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2 j: v/e are going to produce a viable result. So all I'm trying to 

ii 

3 ij suggest is those numbers themselves input, are ' immaterial for-

;i ij 

4 ii what he's trying to tell us right now. 

5 I think we should proceed. 

5

 : MR. JORDAN: I echo, don't get locked in at looking 

7 ;, at the numbers. He'is trying to show you methodology of how you 

i I 

• ; i 

8 wold rake the risk numbers that we've generated before and j 

i 

i 

9 .: assuming we haven't come up with the right exposure model, how 

jj 

10 you then go to estimating what the risk is going to be out 

n j, there in the population. 

12 jl DR. SILBERGELD: Well, with all due respect, I 

13 'I think we've spent a lot of time at this meeting talking about 

ji 

u 7 thing's that v/ere then told may have no reality. I would prefer 

15 7 that this Committee spend time focusing in one what we consider 

i 

j to be more closely to the real world situation. 

j I don't feel much interest in considering a scenario 

18 7 where the upper -- the range of blood leads in this country are 

II 

19 ;• going to be something below Nepal. Because I don't think it's 

ever going to happen. 

I think the transfer from maternal to fetal organism 

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jj is going to be in excess of that. We're dealing with risk 

i| 

jj assessment and then some implication for regulation. 

_, !, CHAIRMAN LIPPMANN: Warner? 

2 4 ii 

„ j| MR. NOLL: I wonder given the discussions that we've 

Z 0 I! 

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ij had and. the reservations that manv of us have had about the 

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ij exposure analysis, it's worth going through these numbers. 

ii 

:j It seems to me that going through these last slide in your i! 

:' presentation and discussing those conclusions would be useful 

i! • i 

; and appropriate. But the intervening graphs and so forth, I 

.: think are useful only in showing the form of an analysis that 

!i 

;; might be cone in the future. 

ij 

'i 

!

: DR. WHITFIELD: I would like to say one thing before 

:. we skip to the end. If Ellen, for example, the answer is on I 

ii ! 

;the righthand side and turn cut to be closer to 10, would that; 

ij i 

j| be more believable to you? ' 

!:' i 

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j| DR. SILBERGELD: I just want to say, I have a plane 

''that leaves at 1:30 and I think that this Committee's time 

i! 

jj would be better spent dealing with what we anticipate to be 

the residual effects of lead and the controllability of significance sources. / 

DR. WHITFIELD: Okay, tut I want to tell you that the 

risk estimates that we derive sort of bottom out if you will, 

and they bottom up above 10. And the fact that we show numbers 

here — 

DR". SILBERGELD: Well, that's what I think we need 

to talk about with respect to some of the fetal effects, 

exactly, instead of talking about poor. 

MR. NOLL: Ron, ,1 think many of us have very serious 

reservations about the data from which these numbers came. 

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DR. WHITFIELD: Yes, I appreciate that. 

CHAIRMAN LIPPMANN: Can you push through a little 

faster than and not (laughter) --

j DR. WHITFIELD: We understand the growing concern 

i 

I 

; about the risk estimates. And so we do want to caveat the -- j 

i i 

j j 

• exposure estimates -- so we want to caveat the risk estimates \ 

\ that we have produced. 

i 

; Our main points now are the following: we have 

ii 

9 li demonstrated that dose response and dose effect relationships 

i! 

10 j: can be combined with exposure estimates to calculate risk j 

i i 

estimates. And of course, the whole is no help here than the j 

sum of the parts, and we'renot questioning the sum of the partSecond point is that specific risk estimates are 

j 

open to questions due to the preliminary nature of the exposure 

i 

estimates which are under further evaluation. The third point) 

is that an improved risk assessment would incorporate the 

distribution on geometric mean blood lead levels, rather than 

lowering upper boundsWe found, however, that the difference between lower 

and upper bound estimates was not that great in this case. 

That's notto'say that that wouldn't be true in other risk 

assessments, say involving ozone, as is the case here. 

CHAIRMAN LIPPMANN: Dr. Noll? 

DR. NOLL: I have two questions. The first is, 

I'd like to hear your response to the issue about over 

20 

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confident in the following sense. It's one thing to get expert 

predictions about what day expect to be state of the maximum 

likelihood, estimate of an effect. It's another thing to get 

their subjective estimates about the distrubution function. 

5 \: And I think here in terms of the work of Lichensteiifi 

!! 

6 ji and Ishoff and Slovic who sav that experts svstematically under ll * 

7 ij estimate the variants in their own estimates. And that so 

8 

9 

that if you translate this into a risk assessment, you're going 

to get an underestimate of the degree of variants in the true 

10 i, state of the world bv taking the expert's estimates of variants 

I ' I 

i at the base. j 

The second question I have has to do with the dif- ! 

ference in a basian sense, between expert differences of opinion that differ on different states of information, as opposed 

to differences in interpretation of the same information. And 

in particular, what extent have you or can you imagine collecting information that would enable us to separate those effects 

That is to say, expert responses that differ because they read 

different literature and did different experiments and looked 

at different data, versus expert differences that basically ar£ 

routed in sort of fundamental differences of interpretation of 

the same information. 

DR. WHITFIELD: Well, I think we've addressed" all 

of those issues in the care that we've taken in preparing 

the protocols. For example, I would invite Tom to add to my 

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comments, he's better qualified than I. But I will attempt to 

answer your questions. 

The first, regarding the behavioral work that's come 

out of Oregon Research Institute, I hesitate to call them 

ji colleagues, as I've never worked with them, but we're aware of I 

i their work. It is very important issue. 

i: 

I; 

jl In fact, in the protocol, we address all of the con-

;• cerns that they have raised "in the their literature, concerning 

l

; 

j, over confidence and bias and so forth and so on. And to the 

jj 

|j best of our ability, we've attempted, to point out these pit- j 

i i 

falls in providing expert judgments to the people up front and 

i 

jmade them aware of it, and reminded them of it and I don't 

i 

I know what humanly could be done bevond that to overcome hope-

| 

I fully the effects of people having different information. 

In the protocol, it did point out matters of research that we thought were important to be considered. And 

we tried to be as complete as possible. We brought information 

that we felt was recent and they may not have been aware of, 

to make sure that people had all the same information there. 

Now, in the final analysis, as you saw from the 

judgments that were .put up there, there were differences in 

judgments, and in some cases, they were dramatic. That's just 

the way — 

MR. NOLL: I wasn't criticizing what you've done, and 

you answered the question in a different way — I mean I know 

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i 

j 

i jwhat you've done . I was asking it in a sort of different way , 

| 

2 |'which is that first of all, to tell me that my subjective 

3 jj probabilit y estimates are likely to be over confident isn't --

ji 

4 !' I mean that's not really the problem. A H right? 

I 

5 j I mean, the problem is that it's a behavioral 

i; 

6 : phenomenon that people subject to probability estimates have 

over confidence. And one could, in fact, take historical 

8 ! information about the extent of over confidence and — 

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DR. WALLSTEN: I would like to respond to that. 

i 

j I think that this summary of Slovic, Lichenstein's analysis 

i that you're talking about, it is the common summary of the rej suits, but I think it's a little bit overgeneralized. Much of 

i 

! the research on which this is based concerns asking different 

I i 

people almanac questions, which city is larger, Raleigh or 

Durham or what have you, and how confident are you in your 

answer. 

And the overwhelming result of that kind of research 

is exactly as you described. But the overconfidence is less 

true when you ask experts questions carefully about the areas 

of their expertise. And the most extreme example of that is 

when one look's at probability estimates of weather forecasters 

and one compares — one looks at the so-called calibration 

curves or possibility estimates of weather forecasters and 

they're extremely good. 

.So I think the statement regarding the literature 

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that you're saying is true, but when one asks the right kinds 

! of questions and structures the problem in the right way, 

I 

j it becomes less of a problem. I don't want to say it's no 

| problem, but I believe it's less of a problem. 

i " • 

I 

I MR. NOLL: One comment and then I'll keep quiet. 

I 

i so we can move on. I mean, I don't regard an answer that says 

I don't understand Slovic and Lichtenstein as well as you havel 

it's ridiculous. That's why I framed it in terms of variant 

probability estimates. 

The result that I'm talking about is asking experts] 

about areas of expertise where you basically minimize the 

bias and the probability estimate but you still have a significant effect in terms of the estimate of the variance in the 

subjective probability estimates. That's all I was talking 

about. 

DR. WALLSTEN: I'm sorry. 

DR. MORGAN: How did. you deal with the issue of 

insufficient adjustment having gotten the correct --

DR. WALLSTEN: Well, as much as possible, we tried 

to question people's judgments by posing hypothetical outcomes that would be.inconsistent with the probability judgment^ 

and asking them to consider whether they could imagine scenarios 

that would lead to this. 

And. in general, we tried to stretch their -- I 

don't know whether the term is imaginaticn, but we tried to 

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i j challenge their probability distribution that they gave us to 

li 

2 j- see v.'hether or not they could envision any scenarios that would 

ij . 

3 j| give rise to results that would be surprising, given the probji 

4 !' ability of distributions. 

i. 

11 

5

 :, So it's in that fashion. 

6 :j DR. MORGAN: Upper and lower bounds on these distri7 [[ butions were selected at what stage in the solicitation process? 

i , 

8 ': DR. WALLSTEN: . They were selected initially very 

9

 ; early, but occasionaly had to Le modified because as we went 

10 

i 

1 1 j 

i 

12 j 

13 j 

j 

14 ! 

through the process, we discovered that the upper and lower 

bounds were too close together, and they had to be stretched 

out. 

I apologize for — I didn't mean to misinterpret. 

CHAIRMAN LIPPMANN: I think we'll move on. Thank you 

15 | very much. 

16 DR. ROWE: I have a question, and some of them are 

17 jj — and a mop up . But what I'm trying to understand is, I don't 

j! 

18 ;j understand these graphs tha t have pre-control and post-control 

19 

20 

21 

22 

23 

and at the same time, when we're comparing alternative control 

levels in the post control period. And that just kind of lea 

me comparing "two different time periods with two different 

i 

j lead and soil, lead and diet bases. 

This doesn't seem to be the questionthat i am faced 

24 li 

ii 

25 

with on the panel. I don't understand the second half of this 

analysis coming to those graphs at the end, ignoring the 

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numbers, that are in the graphs. It seems the graphs- should 

; have post control scenario, .5, .75, 1, 1.5 or whatever, and 

j 

j I know in your report, you suggest that the results are not 

l 

I 

| much different. 

i 

; So let's see that or whatever. But we know that 

I 

j the exposures are going down through time and for other factors 

i 

j And that sort of being associated with this lead standard, it 

I seems odd to me. I just don't understand it. 

i I 

I CHAIRMAN LIPPMANN: I think it was difficult to find 

jj the definition of those terms, pre-control and post-control 

anywhere, and it made it hard to read it. And I think the 

I explicit statements need to go along with those scenarios. 

i 

j And if in fact, it doesn't matter what the air lead 

level turns out to be on "what the blood lead level is, that's 

an important conclusion and raises some concern about the 

validity of ambient air quality level at those levels. 

I think perhaps we want to get back to a more genera!, 

discussion of where we stand with the staff paper and what kind 

of recommendations this Committee can provide to OAQPS to brincr 

the staff paper to some final resolution. We clearly have 

focused a lot"of our concerns on the exposure estimation as a 

critical component of the risk estimation which drives the 

concern about setting a standard. 

And it may be unnecessary for us to go into too much 

detail until some very basic changes are made in the discussion 

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107 

1 and the.manner of treatment of data, enabling us to grapple 

2 with what vou really feel confident about, as exposure to 

populations and likely effects. 

So I would like to get some Committee discussion 

going on that and then we have at least from one member of the 

5 ji Committee, a set of recommendations that we'll raise and disj 

j cuss. Just some general comment first. Ellen? 

DR. SILBERGELD: The only general comment I would 

l! 

9 i. like to make is something wc haven't noted, before, and that is 

•' i 

TO jj much of our discussion has fortunately been blessed by the large 

i amount of data available on lead, and we've been able to focus 

down on specific blood lead levels that seem to be associated 

with the appearance of adverse effects. 

We have not discussed the issue as providing any 

kind of margin cf safety below those levels. And I'just want 

to remind us that we heed to consider that if we're focusing 

'in at levels, let's say, we're talking about the earlier 

recommendation of this Committee of looking at children's blood 

maximally in the range of — what did we say -- 15 to 20, 

we're now looking at male blood pressure data in the range of 

10 to 15. We're looking at possible prenatal effects slightly 

below that level. 

I think we need to remind ourselves that we are 

dealing with a certain unusual setting now.of actual focusing 

in on data that show significant effects at those levels, and 

n 

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 10 8 

1 :. we have, not incorporated any concept of providing a protection j. 

ii 

II 

2 !• DR. MAHAFFEY: I think in the areas where we have 

3 ;• some numbers, where this so-called, margin of safety issue 

4 ; would emerge a bit, I think it's absolutely critical to look 

5 at E? as a function of those iron and lead, the data exists to 

5 • do it. I would make that a real strong recommendation. 

7 ; CHAIRMAN LIPPMANN: Any other comments? 

8 . DR. ROWE: These are general comments. I'm kind of 

9 j curious about one thing that seems never to have been discussed 

10 j throughout here, and that is this geometric GSD of 1.4 2 seems 

., j; to be pretty well accepted. And while I was reading that, I 

i12 j-accepted that quite readily as well, based upon the work that 

13 I' was there. 

14 '•' But the more these'two days have progressed, the 

,_ l'more that number seems to be a general population number, and 

15 

,_ lithe more we seem to be talking about point sources for people 

16 1! ~ 

|| 

j!within one to two kilometers of the point source. And I wonder 

1 7 I! 

18 

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jif we couldn't go back to some of the validation data and 

i 

ilook at a GSD for some of those populations closer to the sourc 

i 

jand get one that might be a little more appropriate. 

i 

j CHAIRMAN .LIPPMANN: I think that this is a good time, 

jin light of that comment, to ask Dr. Morgan to share with us 

i 

i 

jhis idea of what's needed and use that as a basis for a 

'committee discussion of our recommendations. 

i DR. MORGAN: Thanks. I've written this as though it 

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i i. it is mv own views, onlv. Althouch I have consulted- with a 

i! 

i! 

2 " number of others and would argue tha.t it become the basis for 

3 .; some text that we collectively work up. 

i • 

4 ;' These are suggestions for undertaking modifications 

5 to the staff paper. There are five of them. The first is to 

6 

7 

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. write a new introduction which provides a more systematic 

catalogue of the air and non-air sources or exposure and their 

relative contributions up front, so that one gets initially 

calibrated on what the problem is and where it's coming from. I 

And then more clearly explains that because of the ! 

; | 

; phase-out of lead in gasoline, EPA's part of the lead problem 

; which was originally a distributed, source problem like other 

1 ambient Pollutants, is becoming increasingly a problem of the 

; control of specific localized sources, 

i 

• One needs to note that other parts of the lead prob-

| 

' lem like the paint problem, for example, over which EPA doesn't 

j have authority, are still very clearly distributed source 

jproblems. And one needs to make it clear that the primary 

mechanism of exposure, at least for that part of the problem, 

for which EPA has responsibility, tends to be as much for 

II 

ij much of it tends to. be via ingestion of dirt and dust and not 

ii 

ij via the direct air exposure channel or not by a direct air 

ii 

;! exposure, so that one has framed the problem up fairly clearly 

!! for the reader in the outset. 

!l 

j| 

ji Then I would argue that the material on health 

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j 

jeffects .needs to come out of the middle of the paper and be put 

uo front, so that the discussion of sources and exposure proi 

i 

jcesses can proceed without interruption. Currently, one has a 

big jumo when you go from Chapter 5 to Chapter 7, you have to 

:sort of carry along in your head a bunch cf stuff out of 5 and 

j 

have it back in your head by the time you come into-7. 

I would argue that one should rework the treatment 

of exposure, making it clearer that EPA's primary concern is 

individual sources. And in particular, I think there needs to 

jbe a critical discussion of the problems of using knowledge 

from area sources for studies of point sources and we heard a 

comment of one piece of that a minute ago. 

We need to focus more on and try to improve the 

material that's covered in Appendix B and especially Table B-2, 

since it drives the bulk of the calculation and also is the 

central contributor to the uncertainty. There needs to be a 

rethinking a considerable reworking of the point source exposure estimates. 

There needs to be greater discussion of deposition 

and size distribution issues, both in terms of deposition on 

and. resuspension from ground surfaces, and also in terms of 

deposition in the respiratory tract. And one needs to be more 

explicit about who is being protected, and what the level of 

protection is to be. 

I have concerns about the 29.9 X approach, 

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111 

particularly because as it's now written, it's ambiguous 

whether that's 9 9.9 percent of people living around these dis3 jj creet sources or 99.9 percent of all people -- or all children 

in the country. 

5 j; And that ambiguity, I think, gives rise to some 

6 || considerable potential difficulty. One needs to put the disi 

i 

•j j cussion of measurement at the back end of the report and let 

i 

8 ,. the proceeding arguments essentially motivate and drive the 

11 

i: 

o 'discussion of what ouaht to be measured. 

I 

! 

10 ii I think that there are really two needs for measure' 

II ! 

i ment. 1) You have to have area measurement to document thati 

i 

the decline of ambient problems dr to keep track of the ambient 

problems so that, in fact, they don't.decline as anticipated, 

one's aware of it, and. 2) one needs clearly measurement specifically to control problems associated with specific sources. 

And these present different data needs, the kinds of 

measurements that you're likely to want in those two situations 

may be different. Finally, I would argue that CASAC should 

recommend that the next time around, that EPA treat the lead 

problem more in terms of sources and less as an ambient standard. 

And in anticipating that recommendation, I think 

that there should be a discussion of the kinds of data that 

are going to be needed to do that right next time. I mean, 

I think we're stuck with roughly the kind of data we've seen 

1 1 

I! 

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1 today on soil, dust, fates and mass balances on children's 

,| , i 

2 uptake and things of that sort. But there's no reason that 

3 : some years down the road, faced with essentially reworking 

4 • this same problem, that we should be forced, to settle for 

5 comparably lousy data. 

6 CHAIRMAN LIPPMANN: Granger has discussed this with j 

7 j seme of us. Others are hearing these recommendations for the 

•t 

8 first time. So I would like those who need to hear him restate 

9 something or clarify something, to ask those questions. 

,1 

10 But before that, let me just amplify one thing, 

11 \ and which follows in part but wasn't specifically stated, 

12 .. that is, you have to justify, if you can, the use of the high 

13 volume sampler in light of these considerations, or any other 

14

 : sampling approach, in terms of frequency, et cetera. And how 

15 ' monitoring stations set up in the era when lead was the 

16 j ubiguitous pollutant. 

17 And really tell you whether you're solving the 

18 : point source lead exposure problem which is the future problem 

ij 

19 I and not th e past problem. 

2 0 jj Dr. Rowe? 

u 

21 ii DR'. ROWE; I have a couple of things I wanted to 

__ .'; either add or clarify. It seems as if, and this has to do with 

23 || the risk assessment integration of the exposure analysis, I 

24 :can understand the logic that seem to have.transpired before I 

25 ' joined, this Committee of not looking at children in lead 

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hemes for setting the standard, and ignoring them in the stand--

2 ard setting process of health effects. But I don't understand 

3 j ignoring them in the risk assessment in the fact that they 

| will face changes in their risk and it seems to be somethina 

i -

1 

i 

5 j. tc be considered, if in fact, you're doing a risk assessment. 

And from your own numbers on page 6.7, there are 

many more of those types of children. Now, I don't know near 

8 ji if they're near the point sources or not, but the magnitude 

ji 

9 of those people are a lot larqer. 

10 

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! 

I The second thing I am adding is Ellen's point before, 

\ the fetuses, the amount of fetuses is equal to or larger than 

I 

j the children near these point sources as well. So the risk 

! assessment seems to be narrow. 

i i 

i I don't know if you have the resources to deal 

with that. But it would be nice if that could be done. 

MR. JORDAN: Dr. Rowe, it isn't that we are ignoring 

these kids in doing the risk assessment. What we're trying to 

do is assess what you get by changing alternative levels of 

the ambient air quality standard. How you alter the risk to 

people. 

And based on what we concluded at the last meeting, 

was that you can change all the air standard all you want to 

change it, and you're not going to change the risk for those 

kids. The paint exposure they get from paint chips are so 

high, that what they get from lead, if it changes, it's going 

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; 114 

to be so small, it's going to be almost immeasurable. So 

i 

that's the reason they're not — 

DR.ROWE: That's because of the non-linearity 

function --

MR. JORDAN: It's because the amount of lead they 

get frcm eating paint chips is so much greater than what they 

would get from out of the ambient air. 

DR. ROWE: I understand that, but I guess it's stil. 

the increments of the children who are getting it from the air 

versus the increment to those children who are getting it --

it doesn't matter unless that curve is non-linear concave, 

so that the response function shows no change out there at 

those higher lead levels. 

If the response function goes like this, the incre-

• mental health effect is even greater for those children. 

i 

j Even though the incremental percent change in lead exposure is 

!verv small. 

i 

DR. HAMMOND: I would like to comment very briefly 

on what I consider to be the inadequacy of the summary of the 

acceptable blood lead based on health effects in children. 

i 

| And. I'm referring specifically to the bottom of page, 

i i 

jChapter 7-84 and onto Chapter 7-85. 

i 

That"is, I think, totally inadequate in terms of 

; indicating what is serious and what is not serious, by way of 

;an effect. And which, if any, of these effects you are 

i 

i 

i 

i 

i 

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1 :. taking into account in recommending this range of maximum lead 

ll 

2

 !! exposure of 15 to 20. 

ii 

3 ii All of that is very inadequately explained. And 

4 : it does not, and I can understand this, take into account two 

5 very important recently accepted for publication papers by 

6

 : Dietrich and by Bellinaer and I say I can understand it because 

!' 

7 j you presumably drew from the quality, QD, criteria document, 

j 

8 the CD and at that time, those papers were not included. 

So although that may, in fact, be the case, I thinkj 

10 that what these papers say is sufficiently important and has j 

!' ! 

11 j. a sufficient impact on your consideration of what is anacceptj , !2 Fable level of lead exposure that should be treated seriously. 

13 |j -And I agree, I think too, that this whole matter of blood presi! 

14 !; sure, you obviously aren't going to solve everybody's concerns 

ii 

15 ';. about blood pressure, blood lead relationship. 

But at least you can make a judgment as to whether 

17 .you are including it or using it as one of your considerations 

18 j: in establishing an acceptable maximum level of lead exposures. 

Ij 

19 CHAIRMAN LIPPMANN: That's an issue which I think 

i 

jneeds to be explicitly brought out. It's now in the criteria 

document addendum a? a significant body of literature which 

i 

i 

I relates to the standard-setting. And we, therefore, I guess 

i 

j • ' 

|I was expecting that itwould be treated'in the next revision of 

i the staff paper. 

! 

i 

; Your preliminary analysis suggested that it would 

16 

21 

22 

23 

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i jj not be a limiting factor, that is a level which protects 

I 

2 ; children, should also protect the adults against blood pressure 

Eut that needs to be more firmly established if that is the 

4 ; case, and clearly if you have two effects which produce a 

5 similar need for a standard, that strengthens the basis for a 

6 i numerical standard in that conceivably data could come out 

! i 

7 ; tomorrow which undermines the credibility of the kids effects.j 

8

 : And you would be left with no credible basis for 

9 i a standard if that were to happen. I'm not saying that it will 

i; 

10

 : DR. FRANK: Yes, two effects and two rather distinct i 

11 j'populations at risk. i 

j | 

12 j CHAIRMAN LIPPMANN: So I guess we encourage you j 

ii ' ' 

13 !; to follow through on the male adult blood pressure population j 

j; | 

14 | risk and come to some conclusion about the standard in that | 

15 j! regard as well as the neurobehavioral effects, fetal effects, 

16 and all the effects that have come up. 

17 j; MR. JORDAN: We're certainly intending to do that. 

j, 

18 j CHAIRMAN LIPPMANN: How you deal with it, we know 

j 

19 jit' s difficul t and how you resolve what risk estimates to use 

20 

21 

22 

23 ji 

24 

I 

25 

in particular, what coefficients, if any, to extrapolate 

jfrom the human experience, which is less said, that comes from 

j 

j a number cf sources and how you evaluate it and use it, we 

i j 

!wish you well.(laughter) 

Members of this Committee may well be willing to 

help vou in dealing with that issue. So I think these are 

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issues that need to be resolved clearly. This is a staff paper 

2 which is still in a Preliminary stage and we're not ready to 

3 give even a conditional approval for it as a scientific basis 

for the standard setting, 

i 

j DR. HAMMOND: Could I ask one thing regarding what 

I ; 

i 

6 |I think is a very important table? And that's the one on page 

i I 

7 j 72 of Chapter 7, which provides the maximum'individual blood 

8 |j lead, level for 99.5 percent of children/ assuming three differji 

9 ji ent GSD' s. 

II . ! 

10 I That is all very nice, but I don't see anywhere, and i i 

maybe I didn't read this carefully enough, but I don't see the! 

basis for selecting one or another of these three GSD's 

as being the most legitimate. Did you do that? 

MR. COHEN: Yes, we state somewhere in this section 

that we — 

DR. HAMMOND: You've got a section in there where 

you document the basis for selecting one o f the three? 

MR. COHEN: Yes. 

DR. HAMMOND: Ok ay. 

CHAIRMAN LIPPMANN: I suggest you move the technica 

error of having uni.ts on GSD. GSD, by definition, has no units 

DR. NORTH: While we're commenting on tables, I would 

like to note that on page 7-71 preceding this, the assumptions 

on food and footnote 4, and the very strong disparity between 

the numbers here and the numbers that are in the exposure 

20 

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j' 11 8 

1 j analysis for the model that is prese:ntedto us. Now,. I underi, 

ii 

2 istand these are different models. This is the model out of 

h 

3 ;the criteria document information and very different in many 

4 i of its characteristics from the other, 

i. 

r 

5 j Nonetheless, the discussion that we've been having 

i6 rl think, notes the importance of food in terms of the backi> i 

7 j ground that may occur in the future. And this question of what. 

i 

8 j, is the persistence of lead in the soil and the way lead may 

9 ;• get into the food chain, as it may effect blood lead in the 

j 

10 ;' future, is a reasonably important issue to be illuminated in 

i , 

i 

n j this strong disparity between the two model calculations, 

ii 

12 !'which are of course, driven by the assumptions", this troubles 

i 

I' 

13 ^ e -

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

MR. COHEN: We try to take a count of those considerations in our outtake model. This is straight out of 

Chapter 13 of the criteria document. 

DR. NORTH: As I understand the assumptions in your 

uptake model, you have a discontinuity in the assumed lead 

in food from an order of magnitude that occurs between 1985 

and 1986. I'm not sure where you got that. 

It" would, seem like a very different judgment from 

what's reflected in footnote 4 in this table. 

MS. SLEDGE: The values that are on the table in 

Section 5 that represents uptake model, those are again for 

1990, the year 1990. So we have those, the contributions or 

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values for dietary -- future projections, 

DR. NORTH: The question is, where do these numbers 

ii 

3 jicome from? What evidence do they represent or what judgment? 

|! 

4 jj And that isn't being made clear. 

il 

5 j; MS. SLEDGE: They're based on this data that are 

i! 

6 j! presented in the criteria document for dietary consumption 

7 jj or dietary intake of lead in children. These are based on the 

I 

8 |; Pennington study which looked at it on food categories and 

jj 

9 I'also included looking at the lead content in foods. 

10 

11 

12 

13 

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And the current mean dietary lead intake in children 

;are presented'in Section 7 of the criteria document and those 

i 

'represent the years 1982-84. And that was our starting point 

I 

jin which we then made projections into the future. 

j The projections thatweremade were based on 

also data reported in the criteria document concerning the 

reductions in solder lead usage that have already occurred 

and that are anticipated to occur in the future. 

DE. NORTH: I don't want to belabor this point in the 

interest of time, but my concern is with page 6 and a variable 

called NA Diet. And the middle column of. Table 3 in the document by Johns'on and, Paul are enclosure 5, in which the number 

in 1985 is 4.5 and the number in 1986 is .55. 

And my request is, if you were going to use that 

judgment or anything like it, please explain why that 

judgmient is reasonable. 

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i 

1 |j . MS. SLEDGE: Okay, the NA Diet that is defined in 

the exposure report, represents the contribution of lead in 

the diet from direct atmosphere absorptions of lead. And those 

4 jl projections are based on our projection of the — source 

i l ' 

5 ij contribution to ambient lead "concentrations . 

CHAIRMAN LIPPMANN: January 1, 1986, lead dropped 

in gasoline. 

j MS. SLEDGE: Most food is grown in rural areas, and 

9 |l s o — | 

li I 

10 j! MR. HAINES: What's your auarrel? If I understand i 

i! 

i 

n j what you're questioning and it's very appropriate, is"we have 

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12 I a very kmr e edge drop, timed on gasoline phasedown and clearly 

n 'I retrospectively i t doesn't look riaht. 

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DR. NORTH: You have a knife edge in one model and 

you have essentially no change in another model and no explana 

tion. Nov/, it's not worth trying to dig this out and make 

sense cf it, and in this meeting, given our time limitations. 

Just put it on your agenda for the future. 

CHAIRMAN LIPPMANN: Paul? 

DR. HAMMOND: I have similar concerns. But I didn't 

say anything because, from our own data in Cincinnati, I though tj 

that the number looked reasonable. I'm talking about the 4.4 

is it, or 2. And I might just mention what that is. 

Oneway of trying to estimate what the background lead 

if you will, is, is to take the population of children of 

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1 i interest and in this case, I'm talking about a population of 

2 100 and some 18 month olds in our study, and assume that the 

3 i major problem so far as -- is concerned, the tantemount. 

| 

4 ij transfer of dust. And I believe that and I believe others 

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5 j'believe i t as well. 

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' And then to make a regression of hand lead and 

iblood lead and aet some idea as to where the intercept is. 

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' .And in this particular population of 18 month olds, it turns 

jout that the intercept on zero -- of blood lead is 6.6. 

i i 

| And if you allow maybe 1 or 2 micrograms per decii 

jliter from inhalation because the air lead in Cincinnati is 

i 

! 

.25, then you're up there in a reasonable range and you're only 

somewhat higher than your 4.2. I didn't raise any questions 

ii 

jj simply because I had some personal comfort with the numbers. 

MR. JORDAN: I don't think you're arguing with the 

j numbers. You're arguing with the explanation. We didn't explain 

where it came from and that's a valid argument. 

DR. SILBERGELD: Well, I think that this speaks 

to a continuing issue which is sort of a lack of historical 

consciousness about lead. And no matter what you do now, there 

is a huge amount of.environmental lead. 

And I think all our concerns about these predictions 

about blood leads of 1.3 and food leads falling to very small 

| levels, reflects some sense in your mind that things are going 

to change instantaneously through some imposition of one source 

EXECUTIVE COURT REPORTERS 

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P.24 

- , • , • , 

122 

the emissions into air. 

2 And I think what we're all trying to tell you is, 

3 that even if you were to remove all ongoing lead, sources right 

i now, there's going to be an environment contaminated with 

i . i i 

5 j lead and I think the NAS document speaks so eloquently to this[ 

i I 

the 1980 report, that you cannot ignore that. You can't pre7 'tend that's going to vanish as you do something about these |i 

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8 j! source s 

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DR. WESOLOWSKI: Another way to put it is that 

most, of the lead that is in the environment now will be in the 

environment even when you get done with your most stringent 

regulations. And perhaps the Committee should recommend that 

there be a separate section bold one, which states this and 

explains why, so that the reader'in context, realizes that 

your role now as regulators is not going to be in the future, 

a driving force to get rid of lead in the environment. 

So a separate section. 

DR. MORGAN: This is precisely what I had in 

mind when I argued there ought to be this introduction which 

essentially provides a systematic catalogue and ranking, not 

just of the air, but non-air and all the other sources. So 

one can put this particular piece of the problem in a broader 

integrated parameter. 

DR. WESOLOWSKI: So we're helping you write it here. 

DR. SILBERGELD: That gets back to the point that 

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1 ; Dr. P.owe. made, which is then the issue of the marginal increij 

2 j ment in contribution, becomes very important. 

3 j1 MR. JORDAN: I'm not arguing that the lead is going 

4 i to be around, and I don't mean to argue that away. But when 

ji 

5 you're trying to assess what the intake of lead is going to be 

5 ; in the human body in some future years, you have to break the 

7 j' problem down into the individual elements to which he's going 

8 i to be exposed to. 

9 !• As you look at those individual elements, as we have 

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-,0 ; in this analysis, you get the indication that those things are 

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'going to go down. For example, the dust in the house, the lead] 

content is going to go down as lead in gasoline goes down. I 

13 !• I don't want to get into a belabored point but--

|' 

K j[ CHAIRMAN LIPPMANN: Well, we' re asking you to take 

ji 

._ j; all these things into account and come up with your best 

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judgments on the future sources of exposure which will — the 

17 jj dif f erent proportions and past sources — 

|i 

18 ji DR. MORGAN: But you might think of it in terms of 

relative effort. I mean, the relative effort that is reflected 

on this staff paper on characterizing those contributions, 

and explaining how the projections were made and so on, or 

t he effort on the ingestion terms which are two very critical 

ingredients to the analysis, is much lower than the effort on 

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ia varietv of other things which I think the Committee is tell24 ;. 

Ij 

-_ ji ina vou probably are more second order in terms of the bottom 

2o Ij -

 J 

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n 

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ij EXECUTIVE COURT REPORTERS 

jj (30i) 365-0054 
P.26 

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line. 

124 

DR. WESOLOWSKI: And there are sections missing, for 

example, the number of children who use folk remedies which are 

4 | essentially pure lead. 

MR.JORDAN: I'm sorry, I didn't --

DR. WESOLOWSKI: Well, there's no mention at all 

about the population of Mexican children who live in this 

country who use folk medicine, which is -- and just at least a 

mention to alert people to this problem because it's so 

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deadly serious when a child does use it, even though we don't 

have a feeling for what the number is. 

It's not meager, and we find them every year. 

That could be in there. 

CHAIRMAN LIPPMANN: Tim? 

DR. LARSON: I have -- given that there's a consensus 

that there needs to be some focus on the sources that will 

continue to exist beyond some date in the near future, and 

!that there's concerns about how to characterize the exposure, 

is that the same or different from the general population exposure up to this point? 

We*'re operating on an assumption that a quarterly 

average or a monthly or something inbetween is an appropriate 

averaging time for a standard, given that we're going to have 

a standard regulated that way. But I heard Dr. Hammond make a 

istatement yesterday which intrigued me. I wish he would expand 

EXECUTIVE COURT REPORTERS 

(301) 505-0064 
P.27 

!! 125 

ji 

i •; brief Iv .on this, and. that is that near these smelter- sources, 

2 !i in his experience, the blood lead levels in the children and 

3 ,i perhaps the people there, do not change or there's a large 

• i 

£ '\ reequilibration time or lag time or something such that an 

i ' 

\1 

5 extreme view might be that the blood lead monthly fluctuations 

6 ''aren't going to make much difference. That there's a longer 

| i 

7 ij averaging time in this case, and that perhaps we ought to be 

8 j concerned about -- dare I say it -- a annual average or some 

9 i longer term average for a standard that reflects that "particui, 

10 :. lar phenomena near those sources which now may be "of more coni , 

n jj cern, and if that is the case, this may obviate some of the 

i : 

12 li problems that vou discussed about trving to get a stable 

li 

13

 l; mean predictor. 

: i 

l i i 

14 ji CHAIRMAN LIPPMANN: Dr. Angle ? 1 

DR. ANGLE: Certainly we've all been talking around 

the point that the air model for lead is not anymore appropriate 

than using the air model for radium, simply because you're 

j dealing with the question of high residue which does not disappear, even in ten years time. 

I would like to think that tho. error in the disaaaregate model for. 5.1 or might be corrected for Tables 

i 

j 5.1 and then as interpolated on 7.10, is to use the basic 

I uptake based on the previous standards. In other words, that 

j 

j you assume that the uptake under 1.5 represents the uptake 

from surface residue and that this will not be changed. 

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II 

EXECUTIVE COURT REPORTERS 

(301) 563-0064 
12C 

This is going to be relatively permanent for a long 

'period of time. And that the calculations should use a differjj 

3 -lent — use the uptake at the time of the regulation. 

sl 

4 j1 CHAIRMAN LIPPMANN: Considering the clock and some 

ii 

5 ; airline schedules, I would like to bring our main Committee 

ii 

6 ''recommendation to some sort of a closure as an interim step, 

ii 

Ij 

7 ;!at least. 

ji 

8 ji I ask for comments on Dr. Granger's proposal . I got 

ji 

9 |:some comment related to it and some comment related to other 

! 

10 jiissues . 

ii 

il 

is there anybody who disagrees in any particular 

important respect with the recommendations as formulated by 

Dr. Granger as a committee consensus? I'm sorry, Dr. Morgan. 

DR. MORGAN: I'll give you my copy of this and you 

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can --

CHAIRMAN LIPPMANN: If we do reach a consensus that 

this represents the major committee recommendations, obviously 

it will be transmitted to you word, for word, as edited with our 

— as a committee report. 

DR. FREEMAN: This is our -- perhaps a clarification 

or extension bf one.of Granger's points. He raised a concern 

about using a 99.5 or 99.9 percent level and whether that 

should, be applied to all children or specifically, the small 

group of children around the smelters. 

But I think that also raises the question and I 

EXECUTIVE COURT REPORTERS 

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P.29 

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127 

don't know whether he intended to or not, of whether that 

kind of safety factor is appropriate at all or is the right 

way to frame the question for standard setting, given the smal 

numbers involved and that it is a clearly identifiable group. 

And. if that's what you intend, I heartily second 

that. 

DR. MORGAN: It's not clear to me that it makes any 

sense to frame it that way. It is clear fo me from some discussion yesterday, that if one frames it that way and leaves 

it ambiguous, the argument will then be surfaced. There 

are only a few thousand kids involved here. That's clearly 

less than 99.9 percent of the children in the country, ergo, 

there's no problem. 

CHAIRMAN LIPPMANN: Hearing no descent, essentially 

what Dr. Morgan read, tc you will come to you as a committee 

recommendation and that then leaves us with a few cleanup 

details for us to settle before we can adjourn this meeting. 

CASAC has its own schedule needs and deliberate 

needs and we like to help the Agency take timely actions 

and have promised, in fact, to meet certain time tables. So 

a closure letter on. the criteria document will be forthcoming 

when your satisfied that you tell us that you've satisfied 

our objections. 

And we have a small subcommittee, who will prepare a 

closure letter to the Agency on the CD and Drs. Mahaffey, Frank 

EXECUTIVE COURT REPORTERS 

(301) 555-0064 
P.30 

128 

and Larson will be assisting me on that. I wonder, Les, if 

j you can tell us what your course of action is in making these 

changes that we have asked for, so that we can be satisfied 

7 I 

4 i; that the chanqes in our motion. 

|i 

5 .- Whether the ozone meeting is a good time frame bei, 

5 j. cause we happen to be all getting together again in a little 

over a month. 

j DR. GRANT: Let me just clarify. You're saying CD 

i and let's be clearly separated from addendum? 

ii 

jj MR. JORDAN: That's one package. 

j

1 DR. GRANT: Okay, that's what I mean. 

i 

jj CHAIRMAN LIPPMANN: We hope so. I mean, there's no 

jj 

i! point in closing on part of the criteria document if we' have 

II - . _ 

ii 

jj the whole thing available to us. 

i

: 

jj DR. GRANT: Okay, the-criteria document itself, 

; is basically as Dave Weil indicated yesterday, ready to go. 

I 

i 

!There's are very few minor --

I 

j CHAIRMAN LIPPMANN: I don't see any point in rushing 

to say that's closed and the addendum isn't when the addendum 

is not that far behind. So all you may still want to call it 

an addendum and stable it in the back instead of incorporating 

it into the body. 

What we want to close on is the ECAO effort on lead.j 

DR. GRANT: Okay, I'm not sure how long it will take 

to incorporate revisions, or whatever, into the addendum. 

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EXECUTIVE COURT REPORTERS 

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P.31 

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1 Given some other things, like preparing the PM — but I can 

li 

2 'give it a try to incorporate changes or whatever, into it. 

3 And I don't know if it can be done in time for your very next 

4 meetincf in April. 

I can give it a try and hope that we can do it. 

I would have to work very quickly to incorporate the kinds of 

changes you're talking about. And basically to clarify that, 

it's my understanding as far as the hypertension thing, for 

example, to characterize the state of the published literature 

and these unpublished analyses will come out through this 

review, state the uncertainties, characterize what they are, 

and many points of controvery, whatever, and leave it at that. 

And then review the other kinds of expansion in 

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certain areas that have been discussed, for example, like 

Ellen Silbergeld. I can give it a try to try to have it 

' turned around. 

CHAIRMAN LIPPMANN: We don't want to hold up the 

j publication of the CD, but I really don't see any point in 

ii 

• telling you to orint the CD without the addendum when the 

ji 

['• lead process is not over. OAQPS has a lot more work to do. 

\' DR*. GRANT.: Sure. 

i- CHAIRMAN LIPPMANN: So we would like to get back 

I from vou what you plan to do about finishing the addendum, and 

i 

' then we can respond in terms of coming'to closure. 

I DR. GRANT: Okay, we'll give it a shot and try to 

j: 

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i! EXECUTIVE COURT REPORTERS 

j ; 

j-! (501) *65-C'J64 
P.32 

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j 130 

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have it.back to you essentially within the next month so that 

you will be in a position to look at it. 

j CHAIRMAN LIPPMANN: At least Lf not the complete 

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! document, how your time schedule and plan to finish it up, okay' 

i 

DR. GRANT: Okay. 

CHAIRMAN LIPPMANN: It's not too early, as we are 

I 

i 

j closing on the criteria document, to begin to get busy on 

i 

i 

i another task that's a CASAC responsibility, and that is re-

> 

! search recommendations. And a subcommittee consisting of Drs.j 

; Weir, Hammond, Silbergeld, North, Larson and myself will j 

j attempt t'o come to grips with the research issues related to 

i 

j lead. 

| Whether not this is another five year round or not, 

j there are still research needs with respect to lead that EPA 

I 1 

has to grapple with and. since we've benefited from this review 

of the lead issues, we feel obligated to follow through on 

research recommendations on lead. 

I 

And so for your information, this subcommittee will 

be dealing with your office and others on formulating research 

recommendations on lead. 

DR'. GRAN?: Essentially using the same sort of 

approach that we did last time on the other ones? NOX, PM--

okay. 

DR. MORGAN: When is the right time for this 

Committee to hold a discussion on how this problem ought to be 

EXECUTIVE COURT REPORTERS 

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j 

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! 131 

approached, in a future itterat.ion? Should that be maybe held 

j for the next CASAC meeting on lead? 

i 

| CHAIRMAN LIPPMANN: Well — 

j 

i DR. MORGAN: It does strike me that this Committee 

ought to held such a conversation at some time, although I 

i 

i acree -- j 

i " i 

j CHAIRMAN LIPPMANN: We've already discussed it, and j 

1 ! 

! . . 

• since we do have to meet as a committee again with another j 

i 

• draft of the staff paper, we have -- we will try to come to j 

i • ' i 

! that recommendation, I think, at that next meeting in terms of ; 

' • i 

i j | 

i a formal recommendation. j 

|i ! i 

j DR. WESOLOWSKI: In light of the discussions we've j 

i 

had over the role of lead and air and other media, maybe it j 

would be really useful to change our name from Clean Air j 

i i 

Scientific Advisorv Committee to Multi-Media Scientific j 

i 

Advisory Committee (laughter) so I make that a point. 

CHAIRMAN LIPPMANN: One way to clean up our mission 

is to get rid of lead. I think in discussing it with staff, 

that the best thing to do would be to encourage you to utilize 

members of this Committee in whatever efforts you need to 

come to grips* with f-e risk assessment-issues. 

Any final words from anybody on the panel? If not, 

then I thank you all. It's been a very interesting meeting, 

I hope a productive meeting, and I appreciate your cooperation 

from EPA and all the contributions from the people on the 

EXECUTIVE COURT REPORTERS 

(301) 365-0064 
m, . 

132 

1 panel. . 

"JT/SH 2 jj (Whereupon, at 12:25 p.m., the meeting was concluded, 

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jl 

EXECUTIVE COURT REPORTERS 

(301) 565-0064 
TT ' 

ENVIRONMENTAL PROTECTION AGENCY 

CLEAN AIR SCIENTIFIC ADVISORY COMMITTEE 

SCIENCE ADVISORY BOARD 

P.35 

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March 24, 1986 

EXECUTIVE COURT REPORTERS 

".Ol': 5r^-v>"4