United States
                     Environmental Protection
                     Agency
Office of Health and
Environmental Assessment
Washington DC 20460
                     Research and Development
EPA/600/S8-87/002 Jan. 1 988
&ER&          Project Summary
                    Characteristics,  Deposition  and
                    Fate  of Inhaled  Paniculate
                    Matter
                     David Armentrout and Barbara Locke
                      Accurate estimates of deposition and
                    fate for particulate  matter in the
                    respiratory tract are difficult to make
                    because  of complexities in particle
                    composition and morphology. Several
                    deficiencies in information further
                    complicate the ability to make accurate
                    estimates. Available models for making
                    estimates range from simple models
                    based on assumed particle size distri-
                    bution to more complex models based
                    on a variety of parameters. Most work
                    in the area of estimating particle fate
                    following inhalation has been done on
                    aerosols of known composition. Addi-
                    tional work is needed to categorize
                    properties of inhalable particles with
                    respect to compositon in addition to
                    morphology. Additional  research  is
                    needed to define the effects of pulmo-
                    nary disease on particle clearance from
                    the lung.  Additional research also is
                    needed to better explain the mechanics
                    of clearance from the pulmonary region
                    of the lung.
                      This Project  Summary was devel-
                    oped by  EPA's Office of Health and
                    Environmental Assessment,  Washing-
                    ton. DC, to announce key findings of
                    the research project that is fully doc-
                    umented in a separate report of the
                    same title (see Project Report ordering
                    information at back).


                    Introduction
                      Site- and/or  situation-specific expo-
                    sure assessments often require incorpo-
                    ration of  new procedures  and new
                    information. One area where  additional
                    information is needed is that of exposure
                    assessments  dealing with the fate of
                    inhaled particulate matter. The purpose
of this report is to present information
available  for use in estimating the
fractions of  inhaled  particles that are
absorbed by the lung  and for estimating
the  fate of  these particles following
absorption.
 The final project report, summarized
herein,  includes the  following specific
areas of investigation:

• Summary of current information on
  types and characteristics of inhalable
  particulate matter. The  final report
  defines the commonly used terms for
  classes of particulate matter, and also
  summarizes size and chemical com-
  position of particulate matter from the
  most common broad categories of
  combustion  and process emissions
  sources.

• Summary of information that may be
  useful  in describing current  tech-
  niques  for estimating absorption of
  particulate matter. The  final report
  summarizes current information on
  deposition and clearance of particles
  developed from a  survey of studies
  identified through a literature search.

• Determination of  the influence of
  various physical  parameters  on
  regional distribution and retention of
  particles within the respiratory tract.
  Summary of information on breathing
  patterns,  age,  effects of  pulmonary
  disease, and the general  influence of
  physical and chemical particle char-
  acteristics relative to depositon of
  particulate matter.

• Description of lung  damage caused by
  particulate matter  and the relation-

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   ship of the damage to altered retention
   characteristics. A discussion  of the
   type of information available  is
   presented.

• Provision of information on the dis-
   tribution of paniculate matter to target
   organs of  the body following lung
   absorption or absorption through the
   gastrointestinal tract following elim-
   ination from the lung. A discussion of
   the  problems  associated  with the
   pollutant-specific nature  of the avail-
   able information is included.

  An  extensive  literature  search was
conducted to determine the availability
of data in  each subject area and the
applicability of the  data to  improving
current risk estimating techniques. The
literature search produced a list  of 405
references, the most pertinent of which
are included in the final report.
  Similarly, a large  volume of informa-
tion is  available for  use to  improve the
current method of estimating the fate of
inhaled particulate matter; unfortu-
nately, this information is  not in sum-
mary forms that can be readily applied.
Additional work is  needed to develop
adequate particulate matter  classifica-
tions and data  summaries. Because  of
the volumes of data  involved,  the devel-
opment of useful  summaries  would
require an effort beyond the scope of the
present effort.

Discussion
  Existing models can predict  particle
deposition and retention in  the respira-
tory tract. These  models are  based
primarily on  the behavior of particle
classifications  according  to  size and
solubility. Literature searches identified
several  of  those  models which  show
reasonable correlation with  predicted
results.
  More is known about deposition and
clearance mechanisms in the extratho-
racic and tracheobronchial  region than
in the  pulmonary region. More  studies
are needed to provide  better definition
of the mechanics of macrophage clear-
ance from the pulmonary region as well
as the mechanics of clearance through
the lymph system. This  research  is
critical to providing  accurate  estimates
of total dose,  including dose to target
organs resulting from absorption  of
inhaled particles.
  Summaries of gross classifications of
particles based on size distribution and
solubility characteristics are included in
the final report. These summaries were
taken primarily from two sources pub-
lished in 1982 and in  1967.  Expanded
summaries more adequately character-
izing common aerosols are probably now
available, and a new literature search
may reveal better data regarding aerosol
composition and physical and chemical
characteristics.   Existing   industry-
specific studies  provide more in-depth
characterization  of emissions  from
industrial processes. Compound-specific
aerosol  data may provide a better basis
for estimating probable particle  size
distribution in cases where the particle
size distribution is not known.
  Studies have shown the importance of
age, breathing patterns, physical  and
chemical  properties  of particles,  and
pulmonary disease on  particle  deposi-
tion. Relatively few studies have been
performed, however,  regarding the
effects of age and pulmonary disease,
and significantly more  research  is
needed in those two areas. With respect
to physical and  chemical  properties, a
number of studies  have been conducted
concerning the influence of electrostatic
charge, particle morphology, hygroscopic
properties, surface coating, and toxicity
on  absorption. For example,  numerous
studies  have attempted to characterize
the  effects of  inhalation of various
sulfates.  Data  are also  available  to
characterize the physical and chemical
properties of classes of organic and metal
compounds. These data are not consid-
ered in  available exposure models, but
they are  important for assessing the
clearance and distribution characteris-
tics  of metal  and  organic compounds.
Summaries of data useful for exposure
assessments are  not available  in the
present references; compilation of such
data is beyond the scope of this report.
Classification and summarization of data
on specific organic and  metal compound
classes  from the voluminous available
data should  significantly enhance the
capability  for   making    exposure
estimates.
  In conjunction with  classifying  and
summarizing available data  on the
chemical and physical  properties  of
inhalable particulate  matter,  a compar-
ison of the assumptions used in the most
commonly available  exposure  models
would be useful in assessing the state
of  the  art  for  estimating  exposure.
Literature sources discuss experimental
results related to specific models, but a
comparison of assumptions and param-
eters used in the various models has not
been documented.
  The most immediate needs for improv-
ing exposure assessment techniques are
the development of an improved classi-
fication system  for estimating particle
size  distribution  and  a compilation of
pollutant-specific or compound class-
specific chemical and physical character-
istics. These would improve the basis for
estimating  clearance  and distribution
over what is available from  current
summaries. The  basic data needed to
accomplish this  may be available from
existing sources.  Assembly of a usable
data base is needed.
  The needs for expanded information on
the  mechanics of clearance from  the
pulmonary  region and for information on
the  effects of pulmonary disease  are
equally critical to the development of an
improved risk-assessment  methodology.
These areas, however,  will  require
significant  resources and time, as they
would  involve extensive laboratory and
clinical testing.

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     David Armentrout and Barbara Locke are with PEI Associates Inc  Cincinnati
       OH 45246.
     Michael H. Shapiro is the EPA Pn iect Officer (see below)
     The complete report, entitled "Ch iractenstics.  Deposition and Fate of Inhaled
       Paniculate Matter." (Order No. PB 87-2J4 854/AS; Cost: $13.95. subject
       to change J will be available only from.
            National Technical Information Service
            5285 Port Royal Road
            Springfield. VA 22161
            Telephone: 703-487-4650
     The EPA Project Officer can be contacted at:
            Office of Health and Environmental Assessment
            U.S. Environmental Protection Agency
            Washington, DC 20460
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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Penalty for Private Use $300

EPA/600/S8-87/002
            0000329    PS
                                           60604

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