Uml«d SUt«s      Olfta* 
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                                               EPA-SAB/CASAC-89-001
           UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

                       WASHINGTON. D.C. 20460
                         October 6,  1988
                                                        OFFICE OF

                                                     THE ADMINISTRATOR
Dr. Roger McClellan, Chairman
Clean Air Scientific Advisory Committee
Science Advisory Board (A-101F)
U.S. Environmental Protection Agency
Washington, DC 20460

Dear Dr. McClellan;

     This  letter  transmits the conclusions of  the  CASAC  Acid
Aerosol  Subcommittee  concerning  listing  acid  particles as  a
criteria pollutant.  The Subcommittee met on June 14-15,  1988  in
Washington,  DC to review the draft "Acid Aerosols  Issue  Paper"
(EPA/600/8-88/005A)  prepared  by EPA's Office  of  Research  and
Development.

     The Subcommittee concensus, although not unanimous,  was that
CASAC  recommend  to the Administrator that he  consider  listing
acid  particles under  Section  108 of the   Clean  Air  Act,  In
the Subcommittee's view, the cumulative  evidence provided by the
available  animal,  controlled human exposure,   and epidemiologic
studies  clearly suggests  possible   health   effects associated
with  exposure  to  acid   particles.   The  Subcommittee recognizes
that the  available data base is not  complete   but  is concerned
by  the  potential  health  risks resulting  from   exposures under
typical   ambient  conditions.  The  -Subcommittee   conculded that
the  weight of  the evidence  from the  disciplines   of   animal
toxicology,  controlled  clinical studies,  and   epidemiology   is
sufficient at  this time  t© recommend that  the Administrator
consider listing of acid particles as a criteria  pollutant.

     In  summary,  it should  be noted  that the majority  vote  was
cast  on the basis of the weight ©f the evidence  from  the  three
health  related  disciplines  rather  than on  any single  study.
A  more  detailed  discussion of  the Subcommittee  position   is
included in the attached report.
                              Sincerely,
                              Mark J. Utell, MD
                              Chairman
                              Acid Aerosol Subcommittee

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                  ACID AEROSOL SUBCOMMITTEE

                   RECOMMENDATIONS TO THE

           CLEAN AIR  SCIENTIFIC ADVISORY COMMITTEE


                              ON

POSSIBLE LISTING OF ACID AEROSOLS AS A CRITERIA AIR POLLUTANT
                   FINAL SUBCOMMITTEE REPORT
                        OCTOBER 6, 1988
             U.S. ENVIRONMENTAL PROTECTION AGENCY
                    SCIENCE ADVISORY BOARD
                        WASHINGTON, DC

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                           ABSTRACT
     Under  Section   109   of  the  Clean  Air  Act,  the  U.S.
Environmental Protection Agency  (EPA) is required to periodically
review  national  ambient  air  quality  standards  (NAAQS)  and  the
criteria on  which  they are  based.   The  Act  also requires  the
Clean  Air Scientific Advisory Committee  (CASAC)  to  provide
scientific advice on  any additional knowledge that is required to
evaluate existing,  or setting new or revised NAAQS.   To  evaluate
the health effects of the  class  of  air  pollutants  known as  acid
aerosols,  the Committee  requested  that EPA prepare an "Acid
Aerosol Issue Paper".  This Issue Paper was  reviewed by  the  Acid
Aerosol Subcommittee  of CASAC in June 1988.  This report presents
the conclusions and recommendations  of that  Subcommittee as
transmitted to the  CASAC.
Key. Wordsj_  acid aerosols,  acid particles, NAAQS

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              U.S. Environmental Protection Agency

                             NOTICE
     This report  has  been written as part  of "he  activities  of
the  Science  Advisory  Board,  a  public  advisory group  providing
extramural scientific Information and advice to the Administrator
and other officials of the Environmental Protection Agency.   The
Board Is  structured to provide  a balanced  expert  assessment  of
scientific matters  related to  problems  facing the Agency.   This
report has  not been  reviewed  for approval  by the Agency;  and,
hence, the contents  of this  report do not  necessarily  represent
the views and  policies of the  Environmental  Protection  Agency  or
other agencies in the Federal Government.  Mention of trade names
or  commercial  products do  not  constitute  a  recommendation  for
use.

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                   TABLE OF CONTENTS




1.0    BACKGROUND	1

2.0    OPTIONS FACING THE SUBCOMMITTEE  	  1

3.0    MAJOR RESEARCH FINDINGS THAT SUPPORT
       THE SUBCOMMITTEE RECOMMENDATIONS .....  2

4.0    REVIEW OF THE ISSUE PAPER	3

5.0    SUBCOMMITTEE RECOMMENDATIONS TO CASAC  .  .  3

       5.1  Recommendation to Defer Decision .  .   4
       5.2  Recommendation Not to List	4
       5,3  Majority Conclusions - Recommendation
            to List   	5

6,0    LITERATURE CITED 	  6


       APPENDICES

       A  -  Roster of  the  CASAC Acid  Aerosol
                    Subcommittee

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              U.S.  Environmental  Protection Agency
             Clean Air Scientific Advisory Committee
                    Acid Aerosol  Subcommittee

                 Recommendations  on  Listing Acid
               Particles as  a Criteria Pollutant
1-0  Background

     Under  section  109(d)   of the Clean  Air Act  the  EPA  must
periodically  review the national ambient  air   quality  standards
(NAAQS) and the air quality criteria on which they are based, and
must  revise such criteria and standards as  appropriate.   In  the
process  of  reviewing new scientific studies   concerning  health
effects  of  particulate  matter and sulfur  oxides   in  1986,   it
became apparent that researchers had identified acid aerosols   as
a constituent of the airborne mix of these pollutants that may  be
associated with  observed health effects.  As a result, the  Clean
Air  Scientific Advisory Committee (CASAC) recommended  that the
Agency  prepare  an  Acid Aerosols Issue Paper   to   evaluate the
emerging literature concerning health effects directly associated
with  acid aerosols.

     The  Agency completed this draft Issue  Paper  in early   1988
and presented  it  to the CASAC Acid Aerosol Subcommittee  on  June
14-15! 1988.  The Subcommittee    faced   three  primary  tasks.
First,   whether  available    scientific    information   provided
sufficient     and  compelling evidence  for a listing  of  acid
particles  as  a prelude to  development of a  separate  criteria
pollutant,  second,  to  assess the adequacy  of the   Issue Paper,
and    third,  to  identify and  prioritize  research needed    to
respond  to  the critical issues identified  in   the   draft  Issue
Paper  as  well  as  any  additional  issues  identified  by  the
Subcommittee  itself.  The first and second  issues are   addressed
in  this  report,  the third is discussed in  a   separate  research
recommendations report  (EPA-SAB/CASAC-89-002).

2.0  Options facing the Subcommittee

     In addressing the  listing issue, the Subcommittee considered
the three options presented by EPA in the draft Issue Paper:

          1)  Recommend that the Administrator  consider  listing
acid  aerosols  under  Section 108  of the Act.   This  implies a
judgment that the  available  health effects  information  is
compelling  enough to  require additional  protection beyond  the
current NAAQS,  Within  12  months of a listing  decision,  EPA must
issue air quality criteria and propose  standards.

          2)   Recommend  that   the  Administrator   not   consider
listing  acid  aerosols under  Section  108  of  the Act.     The
available health  effects  information as well  as any new  research
would  be considered  during  the  next  review   of  the particulate
matter standards.

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          3)    Recommend  that  the Administrator  defer  judgment
regarding action to list acid aerosols  pending further  research
on the critical needs identified in  Chapter  8 (Research Needs)
of the draft Acid Aerosols Issue Paper.

     In  its  discussion  of research   issues,  the  Subcommittee
considered  research needs identified by  the Agency in the  Issue
Paper,  research  needs  identified   by the members  of  the
Subcommittee, and    presentations from' the interested public at
the June  14-15, 1988 meeting.

3.0  Manor Research Findings that Supportjthe_Subcommittee
       Recommendations

     The  majority vote was based on the  weight of evidence   from
research  involving the three disciplines of   animal  toxicology,
controlled  clinical exposures, and epidemiologic  studies.   The
key findings from recent toxicology research include? in  chronic
daily  exposures of rabbits  (250 pg/m3 for 1-hr/day, 5 days/week
for one   year)   persistent   alterations of   mucociliary   and
alveolar  particle   clearance,   airway reactivity,   airway
secretory   cell density   and   characteristics,  and  airway
caliber  changes  were produced (Gearhart and  Schlesinger, 1988).
Such changes were  similar to those produced by chronic exposure
to  cigarette smoke,  suggesting that   chronic   bronchitis  could
result  from  more  prolonged  exposures.  Furthermore,  in single
3-hour and 5 days  of 3-hour daily exposures to  ultrafine   acid
coated  zinc  oxide particles  with sulfuric  acid concentrations
in  the range  of  20-30 |ig/B3,     guinea   pigs    developed
persistent   changes  in    vital capacity,    airway   compliance,
lung   permeability,   and   carbon-monoxide   diffusing   capacity
(Amdur and   Chen,   1988).    Similar results   were   obtained with
200 pg/m3 of ultrafine  droplets  of pure  sulfuric   acid.   These
findings  suggest  that  primary  and     secondary sulfuric   acid
occurring  as  coatings   on  ultrafiii®  fly    ash particles  may
be considerably more toxic  than secondary  acidic  aerosol  which
is found  in  the atmosphere in solution droplets.

     Recent   data   from  controlled  clinical   studies   lends
additional   support for a relationship between exposure  to  near
ambient levels of acid aerosols and adverse respiratory  effects.
In  1983,  Koenig et al.,  (1983) identified  allergic  adolescent
asthmatics   as a subgroup responsive to  inhalation of  100  pg/nr
sulfuric  acid aerosols  (30 minutes at  rest followed by 10 minutes
of  exercise).   These researchers have   extended  further  their
observation  in allergic adolescent asthmatics linking exposure  to
near ambient levels of sulfuric acid at  68 jig/m3 with significant
alterations  in  lung function  (Koenig et al., 1988).   The  FEV^
decreased  6%  after  inhalation  of   sulfuric  acid  using   the
previously   described  exposure  protocol vs  1%  decrease   after
breathing air.  Furthermore, the most  recent  findings from   Bauer
et  al. (1988) support Koenig'a  findings  in that  adult  allergic
asthmatics showed  greater decrements in  FEY^  breathing 75   pg/m
sulfuric  acid vs.  NaCl  (control)  for  2 hours  in an environmental
chamber.   Based    on     our   understanding   of   the    current

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data    base,  extrapolation   to  longer exposures coupled   with
more  rigorous exercise could  serve to intensify the response.

     Data  linking   acid    aerosols   with  respiratory   health
effects  emerges   from  the   ongoing   field  studies.   Speizer
(1988)   showed  that  bronchitis  in  10-12  year  old  children   in
four  U.S.   cities varied  from  about  3-11%  from standardized
questionnaire  responses  in direct  relation  to  annual  average
concentration of aerosol H4", with the highest  prevalence in  the
community  with the  highest  annual  average  H+   concentration
which  was    1.8   ug/mj     (expressed    as    sulfuric    acid
equivalents).      Similar associations  were seen  for  other
respiratory symptom responses  in the same  population.   While the
prevalence  data  were  for  the  1981  school  year  and  the
concentration   data   were  for  1985-1988,   it    has    been
established  in other studies  from the six  cities group that  the
bronchitis    prevalence  in  these  cities   were   in  similar
proportion in   this   population in  other  years,  and that  there
was  little variation  in  annual average  pollution levels during
these  years.   There were occasional exceedences of the  current
NAAQS for PM and SO, in some of these  communities during some of
the  years  coverea  by   these studies,     nevertheless,  the
Subcommittee   is  concerned that the   current  MAAQS   may  not
provide adequate protection against  such health effects.

4.0  Review of Issue Paper

     The  draft Issue Paper was generally considered to  be  well
prepared and comprehensive. Most members   of   the  Subcommittee
provided  detailed   written comments  concerning  the draft to the
Agency  during  and   following the    June    14-15,  1988 meeting.
Extensive  discussion  occurred during the meeting which pointed
out the  need  to address certain issues further.   An example of
such an  issue  is  to define  the pollutant  indicator to  regulate,
its form, and measurement methodology.

5.0  Subcommittee Recommendations to CASAC

     Following a careful review of  the Issue Paper and  extensive
deliberations, members of the  Subcommittee  voted  and reached the
nearly  unanimous  conclusion1  that  the   Clean  Air   Scientific
Advisory  Committee  should  recommend that  the   Administrator
consider  listing  acid  particles  as  a   criteria  pollutant.
However, one   Subcommittee  member  was  in favor of  recommending
that  the Administrator not  consider listing acid particles,  and
one member  was in favor  of  recommending  that the  Administrator
defer such  a  decision  until  further research was   completed.
The  minority positions are presented first.
   The Subcommittee vote wass 9 in favor of recommending that the
     Administrator  consider listing, 1 in favor of  recommending
     that the Administrator not consider listing, and 1 in  favor
     of  recommending  that  the  Administrator  defer   judgment
     pending further research.

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5.1  Recommendation to Defer Decision fDr.  Robert  Phalen^

          1)  -Although there is scientific evidence that   airborne
acidity at or near levels found in the environment is  capable  of
harming respiratory tract tissues, I recommend that the   decision
to  list  acid aerosols as a NAAQS be  deferred pending   further
research  directed at resolving several basic issues.  First,  it
is  not at all clear just what the relevant air contaminant   is.
Airborne acidity can be in vapor forms and in particulate  forms.
In  some  cases, the acid vapor exceeds the  particles  in total
mass.   The full combination - that is the total acid  present  in
all forms - is the logical agent to consider for listing   because
that  is what is inhaled*  This is also valid  scientifically  as
many of us believe that an aerosol consists of a two-phase system
of  particles and a surrounding gas.  However,  the  Subcommittee
did  not agree to include vapor phase acidity.  Further   research
will very likely show that "total available hydrogen ion per unit
volume  of  ambient air" is the entity that  relates  to  adverse
biological   effects.    Until   this  research   is   done   our
recommendation  to list will possibly ignore a major fraction   of
the  potentially  hazardous  agent  and  thus  may  under-protect
exposed populations.

          2)    Next,  the  presently  available  human   clinical
exposure  studies are for short periods - usually less  than  two
hours.   Because populations will be exposed for  very  prolonged
periods  additional  studies  are  desperately  needed.     Longer
exposures may show that effects increase upon longer exposure  or
alternatively that effects disappear upon longer exposure.   Such
studies  are critical to defining whether peak levels of  acidity
or  some  integrated measure of acid exposure should  be  listed.
Without  this clarification substantial over-protection or under™
protection could result.

          3)    Finally,  we do not presently have  enough  animal
toxicology data to identify the most sensitive sites  in the  body
with  respect to acid injury.  One must have  such  information  in
order to project what human sub-populations are at greatest  risk
and what the expected risks are.

          4)    Certainly  the acid aerosol  issue   should   not  be
dropped.  The available evidence  indicates  the  real potential for
airborne  acidity  contributing   to  adverse   effects in  human
populations.   However, until the above basic issues  are better
understood   it  is difficult to envision  the   establishing of  a
proper NAAQS,

5-2  Recommendation Not to  List  fDr. Georoe Wolff)

          1)   Health  effects  due  to   acid  aerosols  have   been
demonstrated  in controlled exposures  but only at  concentrations
which  are  much greater than an  order of magnitude  higher  than
typical  ambient  levels.   Even the highest  concentration  ever
reported  in  the  ambient  air is significantly  lower   than   the

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lowest   documented   concentration  ever   associated   with   a
physiological response.

          2)    The  assumption  that the threshold  dose  for  an
adverse health effect is 100 jug/m3-hr  (i.e., 100 /ig/m3 x 1 hour =
10  pg/mj  x 10 hours)  is not supported by any of the  data.   In
fact,   it  is contrary to conventional wisdom  because  the  body
produces  ammonia which will neutralize a certain amount  of  the
acidity.

          3)    I  question the accuracy  of  the  ambient  data,
particularly  the  extreme values, since there  is  no  standard
procedure  for  measuring acid aerosols and the  techniques  used
have not been subjected to rigorous quality assurance protocols.

5.3  Majority Conclusions - Recommendation to List2

     Based  on  its assessment of the  technical  and   scientific
information  presented  in the   Issue Paper,  the  Subcommittee
reached  a  nearly  unanimous  conclusion  that  the  Clean   Air
Scientific   Advisory   Committee  should  recommend    that   the
Administrator   consider  listing   acid   particles    as    a
criteria pollutant.   In  the Subcommittee's view* the  cumulative
evidence provided by the available animal,  controlled human
exposure,  and epidemiologic   studies clearly suggests  possible
health   effects associated  with  exposure  t©  acid   particles.
The  Subcommittee recognizes   that the available data base is  not
complete  but   is concerned  by  the potential health risks
resulting  from   exposures under  typical   ambient conditions.
The   Subcommittee   concluded that   the weight  of the  evidence
from  the  disciplines    of    animal  toxicology,    controlled
clinical studies,   and   epidemiology  is sufficient at this  time
to  recommend  that  the  Administrator  consider  listing  of  acid
particles as a criteria pollutant.

     In  arriving  at its recommendation*  the  Subcommittee  took
into  account  that research currently underway should   begin  to
provide  needed  supplemental  information in  the  next  several
years.    To   further  augment  these   ongoing   efforts,   the
Subcommittee  has  also identified key research  needs   that  the
Agency should begin t© address immediately through a balanced and
adequately  funded research program.   These are discussed in  the
separate report on acid aerosol research recommendations.
   These nine members weres Dr. Mary Aradur, Dr. D©ug Dockery, Dr.
     Robert  Frank, Dr, Timothy Larson, Dr. Morton Lippmann,  Dr.
     Gilbert Omenn, Dr, Marc Schenker, Dr. Jerome Wesol©wski, and
     Dr. Mark Utell.

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6.0  Literature Cited

Amdur,  M.O.-and  Chen,  L.C.  (1988)   Furnace generated  acid
     aerosols;   speciation   and  pulmonary   effects.     in:
     International  symposium on the  health  effects  of  acid
     aerosols?  addressing obstacles  in an  emerging  data base,*
     October 1987;  Research  Triangle  Park,  NC.    EHP  Environ.
     Health Perspect.i  In press.

Bauer  et  al.,  (1988)   Am.  Rev.  Respir. Dis.  137:167.

Gearhart,  J.M.  and  Schlesinger,  R.B.  (1988)   Response of ^he
     tracheobronchial  mucociliary clearance  system  to  repeated
     irritant  exposures    effect  of sulfuric   acid  mist   on
     structure and function.   Exp. Lung Res.: In press.

Koenig, J.Q., Pierson, W.E.,  and Horike,  M.  (1983)   The effects
     of inhaled sulfuric  acid  on  pulmonary function in adolescent
     asthmatics.   Am.  Rev. Respir. Dis. 128i221-225.

Koenig, J.Q., Covert,  D.S., and Pierson, W.E, (1988)   The effects
     of  inhalation  of acid compounds  on pulmonary  function  in
     allergic   adolescent  subjects.     EHP  Environ.  Health
     Perspect.s In press.

Spiezer, F,E.  (1988) Studies  of  acid aerosols  in  six cities  and
     in  a  new  multicity investigationi     design  issues.    In:
     International symposium on  the health  effects of  acid
     aerosols?  addressing  obstacles in  an emerging  data  base.
     October  1987;  Research  Triangle  Park, NC.   EHP Environ.
     Health Perspect.s In press.

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                 APPENDIX A



Roster of the CASAC Acid Aerosol Subcommittee

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                                                                  February 1933
                   U.S. Environmental  Protection Agency
                          Science  Advisory Board
                 Clean Air Scientific  Advisory Committee

                        Acid Aerosol Subcommittee
Chairman

Dr. Mark Utell, Co-Director, Pulmonary Disease Onit, Professor of Medicine
     and Toxicology, University of Rochester Medical Center, Box 692f
     Rochester, NY  14642
Members

Dr. Mary Amdur, Senior Research Scientist,  Energy Laboratorys MITS
     Room 16-339, Cambridge, MA  02139

Dr. Doug Dockerys Harvard University, School of  Public Health,
     Department of Environmental Science and Physiology, 665 Huntington
     Avenue, Boston, MA  02115
                                                                          :t
Dr. Robert Frank, Professor of Environmental Health Sciences, Johns
     Hopkins School of Hygiene and Public Health, 615 N. Wolfe  Street,
     Baltimore, MD  21205

Dr. Timothy Larson, Environmental Engineering aod Science  Program,
     Department of Civil Engineering FX-10, University  of  Washington,
     Seattle, WA  98195

Dr. Morton Lippmann, Professor, Institute of Environmental Medicine,
     NYU Medical Center, Tuxedo, NY  10987

Dr. Gilbert Omenn, Professor and Deans School of Public Health and
     Community Medicine SC-30, University of Washington,
     Seattle, WA  98195

Dr. Robert F. Phaleu, Community and  Enviroonental Medicine, College of
     Medicine, University of California-Irvine, Irvine, CA  92717

Dr. Marc Schenker, Director, Occupational and Environmental Health Unit,
     University of California, Davis, CA 95616

Dr. Jerry Wesolowski, Mr and  Industrial Hygiene Laboratory, California
     Department of Health,  2151 Berkeley Way, Berkeley, CA  94704

Dr. George Wolff, Senior Staff Research  Scientist,  General Motors
     Research Labs, Environmental  Science  Departaent, ¥arrens  MI  48090
Execu t ive_Secretary

Mr. A. Robert  FLaak,  Environmental  Scientist,  Science  Advisory Board
     (A-lOlr), U.S.  Environmental Protection Agency, Washington,  D.C,
     20460

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