EPA/SAB/81/Q01
Review of
"Teclffiical Support OociMent for Segulatory Action Against
Friable Asbestos -Containing: Materials in Scliool Buildings"
(Draft dated September 1980)
A Report- o£ th& Toxic Substances Subcommittee
February 19 81
Scisnca'--Advisory Board
U.S.- Environneiaital Protection Agency
Washington,, D,C.
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EPA NOTICE
This report- has-, been: written as- part o£ the activities: o€
the- Science 'Advisory- Board., a: public: advisory" group providing
extramural scientific information, to- the? Administrator and
other officials of the Environmental Protection; Agency. The
Board, is structured-- to- provide.- a. balanced, expert; assessment: of
the scientific matters related to problems facing the Agency-
This report has;* not been reviewed for approval by the Agency,
hence- its contents do; not necessarily represent, the views and.
po.licies- of the Environmental Protection. Agency r nor does
mention, of" trade names1' or commercial products constitute
endorsement or recoiamenda,tion!- for 'use;'*
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Bi.e Science Advisory Board's Toxic Substances Subcommittee met
on .December 2-3, 1980 to consider the "Technical Support Document for
Regulatory- Action. Against Friable: Asbestos-Containing' Materials in
School Buildings" (Draft dated September 1§80). The- Subcommittee
reviewed and commented on the- scientific merits of the document and
responded to specific questions, relating to. the. document,, posed, by
the Office of Toxic Substances-* It should be- noted, here' that the
Subcommittee is; a- general scientific advisory committee-,, not a. panel
of" experts, on' asbestos*
Copies:- of the- Agenda, the* Subcommittee-, roster r and. a listing of.
SAB- and EPA, participants in the meeting are appended (Appendices A,. B>
and' C) » & rough transcript of the- meeting, was. prepared' and has been
submitted to. the Agency ••
The meeting wa# open to. the? public*- The.- Asbestos; Information
Association: provided.-' the Subcommittee with, their: extensive comments
on: the document^ the same> comments previously filed! with. SPA.
Eepresentativ-es!- of. the- Association, made ant. oral presentation and
submitted": a-, brief, written-, statement,,, a-, copy o£ which: is. appended;
(Appendix D) •.
Briefly;,- the Subcommittee* found' the- document to be
scientifically credible but i'tt need: of some8 revisions and; generally
endorsed it. with: the; understanding;: that necessary revisions will, be
made*.
\
Major points which the- Subcommittee- felt need to- be addressed
are as, foTTowsi
1,. 2i e< problems; associated1 with, thet extrapolation;' of available-
asbestos: exposure data* to- long— termy- low-level effects were
notemr-'Ilie Subcommittee- recommends: that, these problems* be
discussed, more* fully in- the- document- Further,, case studies
OIL the: major- cisic of mesothelioraafi- following low- level
asbestos- exposure ' should, be? emphasized,.
2~ Ihe concept of using; only at linear" model to predict risJc was:
questioned.- The subcommittee recommends' that, in. addition
to the linear- model, two- other: models be included r the: one
hit model and' the Weibull model*
3v Hie role of smoking in connection with exposure- to. asbestos
should be clarified- It should be clearly noted, that, while
smoking: affects- mortality rates;- in patients with asbestosis.,
it is not an important, factor in.- increasing am individual's
susceptibility- to asbestosis,- and', all evidence: indicates
that, -smoking- does' not have an effect on\ the: incidence of
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4.. The differential effect, of asbestos exposure, on
children, as distinct from adults, should be reevaluated.
The- greatest risk,- in humans, to low-level. environmental
exposure is: that of mesothelioraa.,. The latency period for
mesothelioma appears to be approximately the.' same* whether ait
individual is- six: years--, old or thirty years- old.
5'.. There are a number of areas in- which, definitions shotild: be
clarified* e..gv/- * discussion of concentrations' and1 exactly
what is-, meant by, exposure and ""lifetime- risJe.,-** There-- are
also a; number of, inferential statements: which- should- be.
reviewed- and revised*
£n The- four external reviews: from. Life Systems, Xnev were
reviewed by- the- Subcommittee- and; seen- as- objective and*
overall,, of very good, quality.. The Subcommittee-- feels, that
it: would' be- of value to have- these four reviews', examined:
once more by the? Agency>
7~ There: should, be? further:' detail on- the measurements
involved:' in asbestos studies-*
The measurement of: similar- siampies- of asbestos;
fiber in- different, laboratories- or evens in. the? same
• laboratory' shows considerable- variation- See* for:
example- Tables; O-l and C-Z (pages; C-*9: and C— 10}
in. "Asbestos-'-s. An Information- Resource," DEBIT
Publication Number (HIE) 79-1681, May 1978*
Variability- of asbestos concentration as a. result of
measurement seriously -flaws- estimates, of risfc from-
coneentration«?tis»e-risJc curves-. (See- discussion- on
p.-C-S,, "'Asbestos; in, Air,-*', in1, above* cited' DBS*
publication* }:
If Epat assumes that the nature;- of the asbestos.
fibers: in, schoolsi is; siitilar- ta that, in* an, exposed-
group-,, th-iss should: be clearly- articulated*.
conversion- number.- (30) ,. presumably derived' from
published^ data,, needs- to- be justified'*
The? use; of concentration, multiplied by durations
(cumulative, exposure) as: a measure- of exposure is of
dubious.- merit,. If possible, some- data-- in which
individuals are exposed, for fixed times: but at. ranging:
concentrations should: be- included.
SisJc. estimates-, may also1 be- seriously affected- by-
conversion- of old-' exposure- data- ta "new" asbestos
concentrations; with, the- 'use,- of fudge- numbers-. This.
should' be, avoided- even, if: some, of the data base is:
lost.. It would: be- better to- present two- sets of
untamp.ered- da-ta to- maintain-, impartiality.
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8. Finally, there- should be an, executive- stanmaryv attached to:
the final document, which clearly reflects the content of the
document.
In addition to these recommendations, the- Subcommittee also
responded to questions; by the Office of. loxic Substances
(OTS) sent to the Subcommittee prior to the meeting^ The O'ES
ejuestionsr the: Subcommittee responses, and: detailed written
comments on: the Technical. Support, Document provided by Dzr. Huth
are- appended (Appendices &„ Wf. and G)-
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tt.S* EHVTHOffllETOLL PBOTECTIOif AGENCY
SCIENCE' AD^rsoar SOAEO
TOXIC SUBSTANCES SOBCOMMITTIE
Conis-ntnee4- Hoom 50 3A
tt* luaptoir Buildia*
December 2-3:,
r Qeoaafa«r.2', 1380:
.2U tacroducciona. ind; Opening; Remarks
af ftaetc
"45: a;,-sr~
8iapp«aeatattves5 of
Odtfttt* o£ Eaforcameitt:
12:45- p-.a-.. C.CKCE'
10';3,0- a,4,ar*. Sta.temen.'c, 'oy teprsseata-tive-s- oi Sir*- Piss;
ASbasrCQ'g-} InforSft-tlOtl A330014.1:1 Off 5
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SCIS8CE aDVISORT 1OASO
TOXIC SOSST&NCES. SUBCOMMITTEE
Oecenber- 2-3:,. 1380
AGENDA
(Co zi tinned)
1980'
9: 00. a. .at.-
fr:l3- at.».
10 -.30 &*&*.
]£,Qrt *i?i5^ £;*&£*->
Opening:1
Chapter by Cn&p'ter Be via* of Technical
Support Oocuseat- far Besnlatorr Action,
Agsiastr. Friable* Asbestas-Carttaiisiag:
tie Seooal Buildings:
19SO) — ' - ^~
of'
Qsaptar* by diaptQZ"
Doc.iaa»irt: (
12:45} jr.ar.
L:30 a.a* General, Discussion: and Plans- for
of
Dr
Or.
Subcommi
Or-
Stali
Oir.
^ Teitaibannr
QT3
Dr.. flnoisa; Te-rub*!^,. Dean,. Sc-hool of Sublie Se&itb:,
Scut'ir. Carolina.
Dr.. fa-rrsa' H. Muir, Deputy- ^ssistaart Ad«inis.tra,to.r" for Toxic
Substancas., Office? at Pesticide's- and Toxic Substance-r, EPA.
Paaxeia-. Russell, Policy ajMt..a*ra,tagsr Sraucii, Office of
sCprcemen.*, EPA
1--.JT.. itgg;r. Executive- Director-/ Asbestos: raforaa-tioir
SU. Ha-rtij'^, is^w,,, sririslajid*- fta*. Silts?, FastrLngfon:, D.C*-
Or-.- iar-ry- Teitelbaun;,, Ptajec.* Iuias,s2r' for- llsfe Assessawat ,
DiTi,s±o'a=,. Of flea- of. Pesticide* aact Tosia. Subg-tancets ^ SP
of
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US~ SHYtHONMfNTAL PROTECTION AS5HCT
$Cte»C£ ADVISORY- 8QAR0
SUSSTAKCSS SU3'COMWITTc£
., '4"1r»a«4 YentOftrfr ETeaA-t fc»a«l af Pti&tie Kaa-Itfr, University of-
Carcrl 1 it*-,.. C&T'uaal*,. &titlr Cftttr-llAc ZS2Q5
.. Mfcitrtir ATextArtarv Fwfwsoi* of S4f T ft
4: H«IT
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j»;lt.iTary TaxfcaTogyi. U
,, Uttt* foefc^ ArtaAsa-s 722H
drv -I. C
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TOXIC SOBST MCSS'
Oftcenfaer 2,-3, LS80
PjirtA el Marcs*
(Actual)
Maisoa- Begogrg,
Drv
Or** J. Qsrence-
flzv Jajne<3: Douglas:
Or* Htatlx1 Lilis •
Or« Margaret: Ma^ttscsn;
* Gtrol tt- Sciitller
Dsr* diftau Brooks
Mr*
Mas* Bemle^ Dart*
Howaxtt
of Pgstleidegr.and tosic
Or*. facrr«tt BE*. SCoir1,. Depoi^" is^tsraat: Actniai strafe r *
.- Jds«p,lt JT* Bfce«ir, CSsemist,, Sxposur^s; S^ntluattloa
^ ?rmaics«: kcefcaastsiff* Sraoative As^iscaat:. tar Associate-
tar- To«±c Stta*tane*F
QienicaeX Bii.g±aeeary Ghanlcaci Cb-mrrols;" 01.7±six>a
Pod'le, Siidsi5i<3'log±*t» SealtlL aa- Eavlronmeat*!- SteasttraoentS' Cb«B±.tt««f, Science AdTlsorr
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w
Asaesros ^ FORMATION ASSOCIATION
jai*«raa
buildings. wi,t±L friabi«t ashes-sea, hav^r be«n. amnftaa±ga4- in
writttair cqri.tiffuesr.&y ffotur esner-ts:' eJsaaan- by S?A taf ss^laW' t=
«axi.y cliis. arammer^
'Cc \& Q£ tthtt? OSttbrtassity
Het-hnayr of
Beto. oi Oxfoed. Oitiimrsity
arlfaorfr a- caoarrl frtn
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failure- to reeogniza that; atucii friable
stam: in. sctoels will be- in aseac*- of
sctccls whera tsmeSwses and atBdaftes-
ara; qnlUeely to be- present for- any
apgrgciable portion, at t£a school day-
higbl? biased. tut* o£ asbestos: aeasuzs-
ccliacirad, by Sebastiext in
Altiiougii ttte: median; imtngtapeatetttg
by- S«J3ast:ieir were 'wall bttlot*
S?Jfe «o!fs • tb* tricsst IJJcaly
aahe-rtos. Iswl, isr. 270
gggttlte o^ th±sp biaged: and iacaa-
plata- aacnoatag- aaaagsmcgfte is tq-
ftfae- UJealy aaepoaurg
school ragjdantg. by g»re ttfrair arc
og
flaws iff. d^e* risjc asgessnent: over—
the^ likaly heahlttfr risjc f CJT
QIC Ssntr *. single spidisasriolo^ie
study far: detarmi'ningr h«aii±;.. effects:
tiiouch-
csndnctad and tae single study
onv by- EPA-., is. not aa»n^ tii* aoart
stndiea- far risk: assessment
p*xcpo*«*v ssartxcnlarly because oa dir«ct
in^onaation' {aitfter on. aa;
ndlyirlual qar e^r«i on
is. availatoia for:
f«£lar» ta- tito- iatet accatmt tarn-.
to, woicir smckintj accoian-ts: for- urucii
o£: tii*. disease in the epidemiology stsidy
«sed' to pcadiet. risks and, tiwa; gr.aat lik-a—
liiiaod: that, smoking pa.titenia' amtcng- school
rasideaty will. WQT gareatly front, tilsoae- at
that cohort..
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failure te predict riste en .&<•
of taadal^- o-tHer tfaan a linear dose
fe£, dasfit*1- the absence of data, indicat-
tJiis; to-- bet- the only appref riata*
ttta- gggtilt: of these glawg la SgAff use o£
;
haarlftte- «videpg» to- gradlctr rialcg.
jsagjdants: is- ta-
rlsJc and, jgdectt to:
HJcellhood that ta fact; amefe
raartdairesc face aer rljir a-t alX, or atr
SB- ..da? acLnifflrt.-'?: and' b
,. a -
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Questions for the' Science; advisory Board, (S&B) by the- Of f Ace-
of Toxic .Substances (QTS) Relating to tne:''Technical Support
Document for Regulatory Action Against Friable Asbestos*Containig
Materials in Softool Buildings" (Draft dated September 1980H
1.. When, smokinf--3pecific data become available from
underlying; study of: asfeestos insulation workers.
^.
to, estimate lung cancer- risks1 separately fear sehoo IT occupants
whet da and- do- not smoke*. Uhe interaction {i.e»* greater
than* additive, effects) between smoking1 and- asbestosTTiads. to
greatly increased risks: for exposed smokers. Tne
of artod'ents who-, smoke can be' estimated; frtanr recent
of smokiag: habits, in: toe tr..S.
QfES tentatively plans tot- conduct: twa- long; cancer^ _Lj ...... -
when: the? data arrive^ one asstsning-' the imteraction:
takes;-- place lit as-besta&j-exposed: students: who.- smokre ..and_ .. ____
one assuming- no interaction-. We would; advise^ decision--makairs;
the prudent course would: be to adont tii& first
Cart.- tae. S&B; detessiriner a. more appropriate: way ta inake use
of tte smoklng.-specif ic: datai for: Ittng- cancer; wnen: they becomes
2* The hazard assessment, contends that, the-: assumption anon Id'- '- -
be; re-examined, tftat gmokars-, exposed, to asbestos.' are. at no- graatez
risk of. planraX tnesothe-licnn^ than, sijnilarlv- exposed nonsmoJcers^
file primarY1 source- of data for questioning; thisras'stffliptiQii' is?
the insulation: workarm study,, thoug-ii- the: evidence is not
persuas'lve on» way or; 'the.- otnes- at. •ais- tiae-- Given this state-
of the evidence^ waat factors'- wculdi the. SJUS. recommend- that
OTS- eonsid'err • in, deciding: whether to. calculate smokii^-specif ie
risk:. est£»a;tesv. foxr p-le-urai' otesotheliomai. when: tfae? data arriire?
1.. The. current, asseasment maJcas no: attempt, to estimate risks
of" morbidity or mortality front- asbestosis:, even for custodians'.
Can-, the.: SAB- suggest a- way to • make- such • estimates , perhaps by
use of- the morbidity data- of Berry et.. al* for British asbestos-
textile workers?'
4,.. The.- current' assessment makes: no.- attempt: to estimate- risks.
of aonf atal Ci..e* t- success'.fully treated) cancer for exposed
school, occupants. Forr some: types1: • of cancer (e.g*,. cancer of
the larynx,! r sole dependence- upon-: mortality data undoubtedly
create*- underestimates of. overa.ll- risk... To- date. OTS has. not
-SI-
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_fQund"~case~fataIity ratios ti.e..,, the- proportion of easel"
"that die- from, 'the- cancers) that would easily '^Hffile""aftidfi"
"estimates to be made* The? only relevant data thatT appear1"' ~
'to" be "available are; 3 -year- aod. 5-year' survival, rates, from
the* Third, national Cancer Survey. Can the SAB identify
case-fatality- ratios- or develop a- method- to the use-
survival rates tor- estimate- increased risks of" eancasr
morbidity?
" ST. The preamble; tot the proposed; rule snows, that. & custociiair
could, easily; double hist or- her "prevailing; "' asbestos. exposure
lay sweeping; foar only S minutes * day> Other reasonable^
sceaariosf of this- type; are not presented,, nor" arer risk. es*imates-
for such. *' typical, individuals^* yet. these are the axpcstire!*
eacpectad ta'b an. apparent, inconsistency and not. a. real one* We
would appreciate,- • the' .advice- of the-. 335" on how to make- this-
judgment clear' to- readers,..
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3. Of. the plausible: dose response curves that could not be-
dismissed. By providing? a poor, fit to available, dose-response
data, linear regression "usually" leads-- to the highest:.
predictions: of increased risk. This. was- thw rationale for
using linear regressie-a for- the- qtmntitativeririsk estimation-*'
Scientists at, the- Constaner- Product Safety Conmissioa informally
pointed out. that when, as- in, the- ease*. of the insulation workers
study,, respons.es exceeds:- 10%, the' one-bit nwSel yields, higher:
risk estimates than linear regression* _' • •
QTSt has, not yet. applied, th* one-hit model in. this ,
assessment , with the under s^tanding- that risk: estimates- "even
higher; than' those we- ofatmirxkl msing, linear regressiom wotrld: not
.alter- regiiiatory decision-majciag;. H«verthel^s> strict-
adherence to the?' decision criteria laid, outf in the doctment
would, raqulra Tiding: the one-hit model* Would; tha SAB. reconmend
applying- the- ona-»hit model- to ootadji the* highest risfc
that cannot, be- gaeudsntly roled out?
$•« at- th® siaggesitioit of1 one of the esttraims-mi revifflfars., CIS"
poc&usnacL the attached- csdcalatdtoov using* *atftr±batsblai risk*
Ctha di^'farence fcetwMit observed; and; expected; death' rates front
cancars).- instaad." of ther "Tifetwue? risk.*
oteasure. Aft. shown, in the Attachment, this, technique could ncrt
applied: completely' because of a limitation- in the- readily
available Il*s7~™fi£,etal3le? nevertheless/, it showed that the
result would; lie within 40%- Q±. the prediction', obtained by the ' *
"'lifetime risk1* metho'd,.. Does the SAB: keiieve* that the attached:
analysis wc^tM: maite the conclusions in, the. Technical Support: "
Docrumen-t elear:er'" and:' more
-S3-
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to-
17 in.
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on** *&*; otoerv«d; mortalitf roe* fisea. asto«ato*»e«l4Pttad
cattcmir among- tint aaa**ts». irmulacioa
octai.ied- rrm th* publiato-d r«cort_of.
.riale i*. 'Sis*- -iiffacaisefr b«t»e4n: tMa-
at la"*") — (l..f't ^ LOT*4} » T.as «. la"* ds*tt»/|»«3«3it ^«ar-* • Si*
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tie iw,1,T. dingasl r ami-, eacir atndenti samdft aa srera^e o£ 5:
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tliat: tie a.&teiteufrafal'» <5aa-ftit rmfie^ wiiX. aociy ta» tse? amrrivors:
tacfr 3oi2a«crami^ 2*s^C"'- ^«" CoJJ.cwi.iaT cyrlrtiilat'i.nff^ masf be- ^ace-
til* I^?f- T.S. li^sfiaM^ forr ^11 erne**: and, ae^es-, f T..S%
1Z ->w5ald: t* «s?«
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tii* group of dsildr^a
be Qsfeiaated by tbi* netted to' k
'cv asfc«*taA e*5>a3tte« in. sctoals
does, not? pessifi. aartandios tie
3Z
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onchanged lit
(««* Tabla 2i. ia
tiiai til* aradictad.
age 32., 58* o£
disd. groat cancgga:
th* obXutiMd life
ta
: ti:a- 32%
canncst;
a**
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Subcommittee Responses^ to Questions' by the. Off ice n of ..Toxic
Substances JOTS) Relating: to the_jvgechnical Support1' obctMtent for
Regulatory' Action Against Frilt?reirMMgstof-€oiitminincr' Materials in ,.
^ " Sept caber 1980)*.
1. When" smoking-specif ic data become- available from the underlying
study of asbestos; insulation workers, QTS-plans to estimate lung
'• cancer risks separately for school occupants- who- do' and- do not
smoke* The interaction (i.e., greater than additive' effects)
• -between- "smoking- and. asbestos- leads, to. greatly increased risks, fair
exposed, smokers. The percentage: of- students who-- -sucker can be
- — estimated from; recent surveys- of smoking- habits—in, the.- 0,S'* -
•". .... The1 Subcommittee' feels that data are • "~~
available: to- indicate- smoking patterns?
- ..... among? high school and; elementary, .school.
students; and; agreed: that there- should- be
v :., some:' evaluation* ---.:•. •-.. -
Z+- Th.e- hazard:. assessment, contends, that the assumption, that smokers' -
exposed to asbestos-: are- at no.- greater; risk of pieural--mesottieliama
than, similarly; exposed, nonsmoJeecp should be reexamined.. ike
primary source- of data? for questioning this; assumption i* the-
insulation: workers, study r though, the evidence is- not persuasive
one* way. or the other: at this- time1*. Given this- state of; the?
evidence-/ what factors-, would' the-- SAB recommend- that OTS consider-
in deciding, whether to. calculate* smoking-speci'fie risk estimates;.
for; pleural mesothe-Iioma when- the- data, arrive?
None
1*. Ifee- current- assessment makes no> attempt, to estimate riska of
morbidity/ or morta-lity from asfaestosis*,> even,' for custodians^. Can-
the SAB- suggest m way to. make sucfc estimates^ perhapsi by; use- o£
the-' morbidity datat o£ Berry &t al. for British asbestos-textile
workers?-
Cfely morbidity- dat* should be estimated;-
foe- both: custodians- and teachers*
4.- The current assessment makes--, no attempt to: estimate risks- of
nonfatal (i.e..,. successfully' treated) cancer for exposed school
occupants. Four some' types: of cancer (e..gv fl cancer of the larynx),
sole dependence upon mortality data; undoubtedly creates
underestimates of overall, risk, fo date. OTS' has not found ease.— -
fatality ratios (i-e^,, the proportion of cases, that die from the-
cancers) that, would easily enable- such, estimates- to- be iaa.de * The
only relevant data, 'that, appear to-- be-- available are 3-year and
5-year/' survival rates from- the- Third: national Cancer Survey.. Can:
the? SKB identify case- fatality ratios or- develop a- method- to use-
survival rates.- to; estimate increased; risks- of cancer morbidity?
Thee Subcommittee- suggests* that the-: Agency-
utilize data available, from the National
Cancer Institute,., Cancers of. the- colon:
and rectum- should be considered as well
as- cancer of. the larynx.
-Fl-
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5. • Use* preamble. to the proposed rule1 shows' tha!i_a custodian could
easily double his or her "prevailing* asSIsfcos exposure- by"" "
sweeping for only 5 minutes a day.. Other reasonable scenarios, of
this, type are not. presented, nor are- risk estimates, for- swca
"typical individuals'/""' yet these, are the exposures' expected to. be
affected most by the. notification provisions- -of1 the rule. Carc the;
SAB' recommend, methods for' developing- additional scenarios of peak,
exposures and estimating the resultant risks to be expected?
Peak, exposures are of very great importance
and must be" taken, into- account* The
Subcommittee;' suggests that the Agency
inquire--, whether data, from: MIOSH' are
available' and could' be used' to. estimate
risk of' asbestosisv lung; cancerv and' - - , -
mesotheliomav
S« The greater remaining life expectancy of children: exposed to
asbestos- places them: at. a greater risk, than- similarly exposed:
adults-*. Ca». the S&& direct, us to- studies dealing* with; the- possible
physiological reasons for: variation lit risic and/or- latency by age?
The- Subcommittee recommends- that Dr., Petals-
comments; be: considered! as well as; the
Turkish, studies on environmental exposure
of children..
7, The document uses, the- observed, number of deaths among the
insulation, workers- as recorded' on the 'death certificate for all
tvpes, of- cancer: other: than;' pleura! and peritoneal mesothelioma*
For the; Jiesotfaeliomasv the observed: numbers- based, on all available
evidence (e?,g>,~ autopsy reports^, review; off Histopathologic
material,, etc*); are?' used1,, at: the cecoramendation o-f the study's.
authors and one o£ the OTS extramural re-viewers^ The reason
that mesotheliomas- are1 often: misdiagnosed and, because the
expectation- o£ these rare cancers in the- general population is.-
virtually zero, comparison with expected deaths- would not. be
adversely affected, OTS- agrees that this, is- the appropriate-
course to- take..
Nevertheless:, it, is, true that individual deaths are. "doubly
counted" by this procedure, persons- whose death certificate
diagnoses of: lung, cancer- were changed by the researchers to
pleura! mesothelioma> in particular. QTS views- this "double
counting" as an- apparent: inconsistency and not a- real one. We
would, appreciate the' advice: of. the SAB. on how -to make- this
judgment clear to- readers*
The Subcommittee,' endorses- the procedure
that EPA,currently followsv
-F2-
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8. Of the- plausible dose response curves that could not. be dismissed
by providing a poor fit to available dose-response data, linear
regression "usually* leads to the highest predictions of
increased risk. This, was: the. rationale for using linear
regression for ttie quantitative risk estimation* Scientists at
the Consumer Product Safety Commission informally pointed out
that when, as in the case of the insulation workers study r
responses'- exceed- 10%r the one-hit model yields higher risk,
estimates than; linear regression*
OTS has not yet applied the one-hit model in this
assessment,, with the- understanding that, risk estimates even
higher than those we1 obtained, using: linear regression, would
not alter regulatory deeisionmakingv
Nevertheless, strict adherence, to the decision criteria
laid out in the document: would require using the one-hit
model » fltould; the SAB recommend-, applying: the? one-hit model.
to obtain-, the highest risk estimates; that cannot be*
prudently ruled oat 7
Subcommittee recommends* us*- o£ three-
ntodels> all of which: will be base<£ upon.
qualitative epidemiologies!, data;, the
linear- model, the one-hit model,, and: the
WedbulX model*
At. the-' suggestion' of one.' of the extramural reviewers, OTS
performed calculations using "attributable risk." (the
<-.:;if f erence' between" observed and" expected death, rates, front'
asbestos-related: cancers) instead" of-, the- "'lifetime- risk1*"
j'v'easure* ISi-iS" technique could; not. be applied completely
•Because of a limitation:- ia the readily available O*.S'»
lifetable-f nevertheless'-/ it showed;- that the- result would'.
lie within^ 40%. of the prediction- obtained by the "'lifetime
risk*-- method* Does the SAB; believe that the attached
analysis would- make; the- conclusions* in4, the Technical.
Support Document clearer and? more- supportable?
; Subcommittee: believes, that: the
attached- analysis does- make the
conclusions in. the technical, support
document clearer and more-
supportable-.
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COMMENTS by 0r. Ruth Lilis m
"Technical Support Document for Regulatory Action
[TSCA.: Section 6(a-> 3 Against friable- Asbestos-
Containing Materials. 133: School Buildings"
(Draft, dated' September 1980)
g3g. AMD PEESlffCa Of FRIABLE ASBESTOS. CONTAINING MATERIALS IF SCHOOLS
Page; 7, It Is act: clear how the-EPA estimated- the' number- of public-
schools' with friable asbestos-containing materials* It
Is, indicated: that out of the 768 school districts* which
responded, to the. survey (these- represented SIS' of the
nation fs: total)» there: were> S422 (out af a total of
737S schools) built OT* renovated after* 1945, 5797
schools; were Inspected and 1.919 (or* 33% of these) were1
identified;' as- having; friable asbestos-containing;
mat aria-Is--.
Since 1016?. schools were- identified: out of a. sample-
representing: &%• of the nation's- schools-, it. Is. unclear
how the- final estimate- o£ 8545' was-- reached1* There- naiS-t
ha.ve> been, additional elements entering; this projection,
and! this is aa insrortant issue which should be fully
presented'.,
ASSESSMENT OF RISE F10M ASSggTPS'.^M,. SCHOOLS
a* , Hazard Assessment
Page 18-,, last paragraph-*
there is? no, convincing: evidence1 Indicating that smoking:
Increase.^' the risfc of" developing' asbestosls1*
b* Pleural and" Peritoneal Meso_thelioma
Pager 22.
In estimating- potential risk for asbestos-related
disease in school, children, teachers- and other
employee*; exposed', in. schools,, the major efflphasis. should
be- on mesotheliomav since this adverse effect has
clearly been."associated-with low levels of exposure,.
such as.' household, exposure- and; neighborhood exposure*
Another' body of information could be used In evaluating
the risk for' mesothe-lloma. Several reports from. Turkey
have Indicated the occurrence of numerous cases of
mesothelloraa with, environmental" exposure to asbestos,
present in'outcroppings- of rocks in various areas of
the country.... 'The- use>. of such mate.rials- for whitewash
of dwellings or-as construction m terial seeds to be
the major' source'' of exposure,- to- the general population.
Attached are copies'of relevant publications on endemic
mesothelioma in Turkey*
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cv Asbestos is
Page 32
The definition: of asbestosis does not include the
severity criterion*. Asbestosis- is the interstitial
pulmonary fibrosis due to inhalation of asbestos
fibers- The pathologic process- can-' progress from early
and slight, changes, to more marked:, abnormalities and
eventually to severe abnormal i ties-*, to restrict the
definition of asbestosis to the * severest- £orm!L is. ...... _.
Page 33. » end of* first paragraph,, to- be- changed:
IF
• «..». r, f.
individuals have- to- be examined for- radiologic
and clinical abnormalities*" The radiologic method- is
th^ single most, important one for the diagnosis of
pneumQCoaloses? ia geaera-1, and- fair asbestosis; Lit
particular*
Pag.e 34--, second, paragraphs
There: is; general agreement» at present,, that asbestos!?
is- not to, be-- restricted for "advanced stages? of- the
disease-" or for "certified,"" asbestos is*
Page 39.,
It is difficult to- understand why the highly
questionable definitions, fotr "possible asbestosis11 and,
"ceft.if.ied: asbestosis" (McTittie, 1965) are used*. The
atteop't to; construct dose—response relationships', for
three- different definitions of asbes-tosi.s. is- of little
relevances
Paga- 39", last paragrapii*.
With, asbestos exposure1- i* the lower rajts^»^-stich- .as-ia _.
household exposure, the- arast prevalent abnonaa-lities:
are pleural flbros.is and pleural calcifications,- Such-
abnormalities- occur often in the- absence of definite
parenchynjal changes (interstitial fibrosis), and they
can be- quite extensive* With environmental asbestos
exposure, such as that reported- from Turkey, pleura!
abnormalities'' (pleural fibrosis-, pleural calcifications
and pleural effusions) are to be found with a- higher
prevalence than radiogrsphically detectable-
interstitial pulmonary fibrosis,.
Page 42,. las-t. paragraph...
The conclusion should indicate that, based on the
available information on effects; of non-occupational
asbestos exposure, there is a, high, probability for
pleural abnormalities- to occur- asv a. result of exposure
in school buildings*
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d. Factors- that Modify the-Risk of sbestos-^-Inducad Disease
Page-'49*
While there is- no, doubt that smoking: affects mortality
rates of patients- with asbestosis, this, does- not
warrant the- statement "Smoking, may also.- be an important
factor in increasing an individual's susceptibility to
asbestosAs*." There is- no convincing evidence- to-- prove
this* '
page- 49v -
.... 'laer* is no effect, of smoking on- the- incidence' of
mesotheliomav The-
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4.
Is t ima te of Prevalent Exposures-.
Page* 65,, first paragraph.
The criteria- outlined, as reasons^ for accepting tiata
from Sebastien et al,. are understood aot to have- been
fulfilled: by U.S* studies oa schools.. It. would be-
appropriate to present more- detailed, comments on the
reasons, for which the U.S. studies did aot fulfill
these- criteria.
f * Risk Assessment
Selection of the- Underlying Study
Page. 73*.
Under the attributes that make- the- selected study ,
(Selikof£: et al.., Hammond et. al*)' suitable- to be taken
as a basis; for making; (juantitative- estimates- of risk
the following;- I* listed:
of" the disease* idea-titled as- hazards, of asbestos:
was; investigated; and1, was-- found to be- in
Tteis- isr ia itself',. no.t: necessa-pily an:
attribute making; the- study under consideration more1
appropriate- as, e basis for estimation- of risk of
exposure ia schools.,
Asbestos: Bgppsur_g-_. Among the Insulation Workers-
Page 77*
The concept of "wasted"" exposure is
not at. a-li. helpful* I suggest: the phrase ""asbestos;
exposure- not affecting: outcome'1' be used.
Increased HjLstfc.. Ataong: the Asbestos- Insula.tign^_¥orkers^
Page 81*
PA definition of "lifetime- risk11 is unclear
(as- presented-' in the text, this-- is "excess risk,1* but
not "lifetime -risk"')* , ---- ....... ---------
Asbestos_J|xpQgurQ- in- School's-
Page S3*
the assumption is. made that, the average student is
first -exposed' at age 1.2*.
Page 84, first paragraph..
It is- then - estimated that, for students-- the- prevalent
concentration has to be multiplied by "15 work years.11
It is: rather difficult to. understand how this- IS fears
figure- was chosen..
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The- paragraph on page 34, providing background
information on the- reasoning followed, is from a
biological, point of view, highly questionable.
3. Final Comments
extrapolation (or Intrapolation) from- a high
exposure1 group, to assess risks of low level exposure,
is fraught with inherent difficulties, especially when
the extrapolation, covers, exposure levels approximately
four orders of magnitude apart* The majott...rls3c.^jut --
lowest known asbestos exposure,, is mesothelioma.. The
numerous cases of mesotheliomas in family.._membejis^-a-f ___
asbestos workers, with neighborhood exposure and with
environmental exposure-, strongly, indicate that a risfc
of developing mesothelioim as: a result of exposure.- in
schools ist real.
I agree* with; most of" the* comments by Petov and witht
suggestions; for the- assessment of health hazards:- due- to
asbestos, exposure1 in1 schools..
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