EPA-600/6-75-001
March 1975
STAR Series
ASSESSMENT REPORT
ON PARTICIPATE POLYCYCLIC
ORGANIC MATTER (PPOM)
SSK
01
U.S. Environmental Protection Agency
^ffice of Research and Development
Washington, D.C. 20460
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EPA-600/6-74-001
March 1975
SCIENTIFIC AND TECHNICAL
ASSESSMENT REPORT
ON
PARTICULATE POLYCYCLIC
ORGANIC MATTER (PPOM)
(Program Element 1AA001)
Assembled by
National Environmental Research Center
Research Triangle Park, North Carolina
for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Office of Program Integration
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental Protection Agency, have
been grouped into series. These broad categories were established to facilitate further development and
application of environmental technology. Elimination of traditional grouping was consciously planned to
foster technology transfer and a maximum interface in related fields. These series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
9. Miscellaneous Reports
This report has been assigned to the SCIENTIFIC AND TECHNICAL ASSESSMENT REPORTS (STAR)
series. This series assesses the available scientific and technical knowledge on major pollutants that would be
helpful in possible EPA regulatory decision-making regarding the pollutant or assesses the state of
knowledge of a major area of completed study. The series endeavors to present an objective assessment of
existing knowledge, pointing out the extent to which it is definitive, the validity of the data on which it is
based, and uncertainties and gaps that may exist. Most of the reports will be multi-media in scope, focusing
on single media only to the extent warranted by the distribution of environmental insult.
EPA REVIEW NOTICE
This report has been reviewed by the Office of Research and Development, EPA, and approved for
publication. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
DISTRIBUTION STATEMENT
This report is available to the public from Superintendent of Documents, U.S. Government Printing Office,
Washington, D.C. 20402.
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PREFACE
Although this report is issued in the Scientific and Technical Assessment Report Series, it differs in several
respects from the comprehensive multi-media format that the Series will usually have because it was nearly
completed prior to the creation of the STAR series in August 1974.
This document was prepared by a Task Force convened at the direction of Dr. John F. Finklea, Director,
U.S. Environmental Protection Agency, National Environmental Research Center (NERC), Research Triangle
Park, N. C. Assembly, integration, and production was directed.by the Special Studies Staff, NERC-RTP.
The objective was to review and evaluate the current knowledge of particulate poly cyclic organic matter
(PPOM) in the environment, as related to possible deleterious effects upon human health and welfare. Infor-
mation from the literature and other sources has been considered generally through December 1972.
A report prepared by the National Academy of Sciences, Committee on Biologic Effects of Atmospheric
Pollutants, Panel on Particulate Polycyclic Organic Matter served as a primary reference for this report. The
National Academy of Sciences' report is based on one prepared under contract to the U. S. Environmental
Protection Agency.
The following members served on the NERC Task Force:
James R. Smith, Chairman Carl G. Hayes
Robert M. Bethea Fred H. Haynie
Harold A. Bond Justice Manning
Ronald L. Bradow Carl T. Ripberger
Robert S. Chapman Eugene S awicki
Jasper H. B. Garner John Sigsby
John J. Godleski Elbert Tabor
Thomas R Hauser Darryl J. Von Lehmden
Anthony Za\ adil, III
The substance of the document was reviewed by the National Air Quality Criteria Advisory Committee
(NAQCAC) in public sessions on January 18, 1973, March 15, 1973, and May 17, 1973. Members of
NAQCAC were:
Mary 0. Amdur - Harvard University
David M. Anderson - Bethlehem Steel Corporation
Anna M. Baetjer— Johns Hopkins University
SamuelS. Epstein - Case Western Reserve University
Arie D. Haagen-Smit - California Institute of Technology
John V. Krutilla - Resources for the Future, Inc.
Frank J. Massey, Jr. — University of California
James McCarrol - University of Washington
Eugene P. Odum — University of Georgia
Elmer P. Robinson - Washington State University
Morton Sterling - Wayne County Michigan Health Department
Arthur C. Stern — University of North Carolina
Raymond R. Suskind — University of Cincinnati
Elmer P. Wheeler - Monsanto Company
John T. Wilson — Howard University
iii
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NAQCAC members were generally in agreement with the conclusions in this report; however, there were
diverse opinions regarding the term carcinogenic as applied to the ambient atmosphere, the concept and
application of threshold values, and the adequacy of the Clean Air Act as amended relative to the problem
of PPOM in the ambient atmosphere. The differences of opinion centered largely upon a universally
acceptable definition of carcinogenic as related to the ambient atmosphere and the term "hazardous air
pollutant" as defined in the Clean Air Act. NAQCAC members generally agreed on the need to control the
level of PPOM exposure; however, there were diverse opinions concerning control options.
A final formal review of the report was conducted by a Task Force that initially convened on July 16,1973,
under the direction of Dr. Ronald E. Engel of the Office of Research and Development, EPA. Members of
the Task Force were:
J. Wesley Clayton, Jr., Chairman Arnold J. Goldberg
Kenneth L. Bridbord Robert E. McGaughey
Kenneth Cantor Robert B. Medz
A. F. Forziati Jeannie L. Parrish
Thomas L. Gleason James R. Smith
Review copies of this document also have been provided to other governmental agencies and to industrial
and public interest groups.
All comments and criticisms have been reviewed and incorporated in the document where deemed
appropriate.
IV
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CONTENTS
Page
LIST OF FIGURES vi
LIST OF TABLES ' ... vi
LIST OF ABBREVIATIONS AND SYMBOLS vii
ABSTRACT . . viii
]. INTRODUCTION 1-1
2. SUMMARY AND CONCLUSIONS 2-1
2.1 SUMMARY ... 2-1
2.2 CONCLUSIONS 2-2
3. EMISSIONS 3-1
3.1 INTRODUCTION ... .... . . . . 3-1
3.2 EMISSIONS FROM STATIONARY AND MOBILE SOURCES 3-1
3.3 STATIONARY AND MOBILE SOURCE EMISSION DATA LIMITATIONS 3-9
3.4 REFERENCES . 3-11
4. MEASUREMENT TECHNIQUES . . . . 4-1
4.1 INTRODUCTION . . 4-1
4.2 PROPERTIES AFFECTING THE MEASUREMENT OF POM . . 4-1
4.3 COLLECTION .... . . 4-2
4.4 INTERFACIAL TECHNIQUES . . . . . . 4-2
4.5 SEPARATION .... .4-3
4.6 ANALYSIS . . . . ... 4-5
4.7 REFERENCES . . 4-8
5. CONCENTRATIONS IN AMBIENT AIR . . . . 5-1
5.1 INTRODUCTION . ... 5-1
5.2 EARLY MEASUREMENTS OF AMBIENT PARTICULATE POLYCYCLIC AROMATIC
HYDROCARBONS 5-1
5.3 ROUTINE MEASUREMENTS OF BaP ON SUSPENDED PARTICULATE MATTER COL-
LECTED BY NASN .5-3
5.4 BIRMINGHAM, ALABAMA, STUDY .... . 5-14
5.5 AZA HETEROCYCLIC ORGANIC COMPOUNDS . ... 5-22
5.6 SIZE DISTRIBUTION OF BaP-CONTAINING PARTICULATE MATTER .. 5-22
5.7 SUMMARY ... . 5-23
5.8 REFERENCES ... . 5-23
6. EFFECTS ON HUMAN HEALTH 6-1
6.1 TOXICOLOGICAL APPRAISAL . .. .6-1
6.2 EPIDEMOLOGICAL APPRAISAL . . .... . . 6-9
6.3 REFERENCES . . . . 6-13
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7. OTHER (WELFARE) EFFECTS . . . - - 7-1
7.1 ECOLOGICAL 7-1
7.2 MATERIALS .... . . . . 7-2
7.3 REFERENCES . . . .7-2
8. CONTROL TECHNOLOGY ... .... . . 8-1
8.1 INTRODUCTION . . • • • 8-1
8.2 STATIONARY COMBUST!ON EMISSIONS •• 8-2
8.3 INCINERATION EMISSIONS .... - -8-3
8.4 OPEN-BURNING EMISSIONS - . - - 8-3
8.5 INDUSTRIAL PROCESS EMISSIONS . 8-4
8.6 MOBILE SOURCES • • • 8-5
8.7 REFERENCES . - - - • • - - 8-6
APPENDIX ~ • • A-J
LIST OF FIGURES
Number Title Page
3-1 Benzo [a] Pyrene Emissions from Coal, Oil, and Natural Gas Heat-generation Processes 3-2
5-1 Seasonal Variations of Benzo [a] Pyrene at Selected NASN Stations . . . . . 5-13
LIST OF TABLES
Table Title Page
3-1 Sources Surveyed for PPOM Emissions ... ... . . . . . 3-3
3-2 PPOM Emissions from Coal-fired Residential Furnaces . . .... 3-4
3-3 PPOM Emissions from Coal-fired Power Plants . 3-5
3-4 PPOM Emissions from Incineration and Open Burning . . . .... 3-6
3-5 PPOM Emissions from Petroleum Cracking Catalyst Regeneration . . .3-7
3-6 PPOM Emissions from Motor Vehicles .... . . . . . . 3-8
3-7 Estimated Benzo [a] Pyrene Emissions in United States .... 3-10
4-1 POM Identified in Collected Pollutants by means of Temperature Programming and Mass
Spectrometry . . . . 4-4
5-1 Polycyclic Compounds Found in Air, Cigarette Smoke, and Exhaust Gases 5-1
5-2 Benzo[a] Pyrene Content of the Air in Selected Cities . . . . 5-4
5-3 Polycylic Aromatic Compounds in the Air of Selected Cities .... . . . 5-5
5-4 Annual Average Ambient Benzo [a] Pyrene Concentrations at NASN Urban Stations 5-6
5-5 Annual Average Ambient Benzo [a] Pyrene Concentrations at NASN Nonurban Stations 5-11
5-6 Ratios of Benzo [a] Pyrene to Total Suspended Particulates and to Benzene-soluble Organics at
NASN Urban Stations ... .... .... 5-14
5-7 Ratios of Benzo [a] Pyrene to Total Suspended Particulates and to Benzene-soluble Organics at
NASN Nonurban Stations . . . .... ... 5-18
5-8 Annual Average Concentration of PAH Compounds in Air over Greater Birmingham, Alabama,
1964 and 1965 .... ... ... 5.19
5-9 Seasonal Average Concentrations of PAH Compounds in Air over Greater Birmingham, Alabama
1964 and 1965 . . ... . . 5.20
vi
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Table
Page
5-10 Interrelationships between PAH Compounds in Air over Greater Birmingham, Alabama, 1964
and 1965 . . 5-21
5-11 Approximate Concentrations of Aza Heterocyclic Compounds in Benzene-soluble Fraction of
Selected Urban Atmospheres . . 5-22
6-1 Relative Carcinogenicity and Mutagenicity of Selected Compounds 6-8
6-2 Lung Cancer Death Rates for Males and Females, Age 35-74, by Smoking Category and Air
Pollution Level . . . . . 6-10
6-3 Lung Cancer Death Rates from Mid-1952 to Mid-1954 by Age, Smoking Category, and
Population Area . 6-11
6-4 Standard Lung Cancer Mortality Ratios in White Males in Urban and Rural Areas, Adjusted for
Age and Smoking History ... . 6-12
A-l Estimated Benzo [a] Pyrene Emissions in United States, 1972 .. .... A-l
LIST OF ABBREVIATIONS AND SYMBOLS
A anthracene /^g
Anth anththrene jj\
BaA benz [a] anthracene /jm
BaP benzo [a] pyrene mg
BeP benzo [e] pyrene min
BghiP benzo [ghijperylene MS
BkF benzo[k] fluoranthene MT
BSO benzene soluble organics NAS
C Celsius (centigrade) NASN
cal calories NERC
Ch chrysene
CHESS Community Health and Environ- ng
mental Surveillance System nm
Cor Coronene NOX
o degree P
EPA U.S. Environmental Protection Agency PAA
Fluor fluoranthene PAH
g gram Per
GC gas chromatography pg
HPLC high pressure liquid chromatography Phen
hr hour POM
K Kelvin PPOM
kg kilogram TLC
km kilometer TSP
m3 cubic meter VPOM
Meal megacalories (106 calories) yr
microgram (10~6 gram)
microliter (10~6 liter)
micrometer (10"6 meter)
milligram (10~3 gram)
minute
mass spectrometry
metric ton
National Academy of Sciences
National Air Surveillance Networks, EPA
RTP National Environmental Research Cen-
ter, Research Triangle Park, N.C. (EPA)
nanogram (10"9 gram)
nanometer (10"9 meter)
nitrogen oxides
pyrene
polycyclic aza arenes
polycyclic aromatic hydrocarbons
perylene
picogram (10"n gram)
phenanthrene
polycyclic organic matter
particulate polycyclic organic matter
thin layer chromatography
total suspended particulate
vaporous polycyclic organic matter
year
Vll
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ABSTRACT
This report is a review and evaluation of the current knowledge of particulate polycyclic organic matter in
the environment as related to possible deleterious effects on human health and welfare. Sources,
distribution, measurement, and control technology are also considered. Results of an extensive literature
search are presented.
Experiments have shown a number of polycyclic organic compounds to be carcinogenic in animals.
Although these same compounds have not been proven to be carcinogenic in humans, evidence strongly
suggests that they may contribute to the "urban factor". In American males, the urban lung cancer death
rate is about twice the rural rate, even after adjustment for differences in smoking habits. Evidence suggests
significant differences between specific urban areas across the United States.
The bulk of the available data is in terms of benzofa] pyrene; so this compound has been used as an index
on particulate polycyclic organic matter. Average seasonal concentrations' of BaP in the ambient
atmosphere range from less than 1 ng/m3 in nonurban areas to a maximum of 50 ng/m3 in rural areas.
vm
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SCIENTIFIC AND TECHNICAL ASSESSMENT
REPORT ON PARTICULATE
POLYCYCLIC ORGANIC MATTER
1. INTRODUCTION
There is substantial evidence indicating a significant difference between the occurrence of lung cancer in
individuals living in urban and nonurban areas even after adjustment for differences in smoking habits. The
reasons for this "urban factor" are not known, but there is evidence that high concentrations of some
pollutants in urban air might be associated with an increased risk of human cancer. However, the specific
causal relationships have not been established. This lack of knowledge constitutes one of the most urgent
needs regarding the problem of the health effects of air pollution.
A polluted atmosphere is comprised of a complex mixture of gases and particles originating from both
natural and man-made sources. Currently, two classes of polycyclic organic compounds are proven
carcinogens in experimental animals, albeit not by the inhalation route. The two—the polycyclic aromatic
hydrocarbons and their nitrogen analogs, the aza arenes-are present in the particulate phase in polluted air.
Occupational exposure to mixtures containing these compounds has led to well documented cases of lung
cancer.
Polycyclic organic matter (POM) is defined as organic matter that contains two or more ring structures
which may or may not have substituted groups attached to one or more rings. POM can be separated into
two portions:
• Particulate polycyclic organic matter (PPOM) is in solid form at ambient temperatures and is defined
as material collected on a glass fiber filter as specified in the Federal Register (Vol. 36, No. 84, Part
II, pages 8191-8195, April 30, 1971).
• Vaporous polycyclic organic matter(WOM) is defined as that portion of POM that passes through the
filter; it will be covered in a separate document.
The aromatic compounds of POM found in the atmosphere can be subdivided into nine groups:
• Polycyclic aromatic hydrocarbons. The polycyclic aromatic hydrocarbons (PAH) usually collected in
the particulate form include chrysene, benz[a] anthracene, fluoranthene, the benzpyrenes, the
benzofluoranthenes, perylene, anthanthrene, dibenzanthracenes, benzfluorenes, the dibenzpyrenes,
indeno [1,2,3,-cd] pyrene, benzo[ghi] perylene, coronene, and alkyl derivatives of some of these. The
latter are usually methyl derivatives. This is of some importance since methylation of a PAH can
sometimes increase or confer carcinogenic activity on the molecule.
• Aza arenes, Arenes are aromatic hydrocarbons. Aza arenes (arenes containing a ring nitrogen) are
usually present in the atmosphere in approximately one order of magnitude lower concentration than
the PAH. Those identified in the fraction of airborne particulates extracted by an acidic solvent
include acridine, 3-methylacridine, benzquinolines, benzacridines, llH-ideno [1,2-b] quinoline,
1-1
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phenanthridine, indeno[l,2,3-ij]-isoquiniline, benzo[lmn]phenanthridine, dibenzacridines, pyridylan-
thracene, and a large assortment of alkyl derivatives of these compounds. However, the basic fraction
of some types of airborne participates and source samples contains a very large number of
unidentified polycyclic compounds.
• Imino arenes. Imino arenes contain a ring nitrogen with a hydrogen. Carbazole and some of its
methyl derivatives are imino arenes found in urban atmospheres. Both these and the benzocarbazoles
are found in air polluted with coal tar pitch. The presence of the carbazoles indicates possible
pollution by fumes of coal tar pitch.
• Carbonyl arenes. Carbonyl arenes contain one ring carbonyl group. Monocarbonyl compounds found
in airborne particulates include 9-acridanone, phenalen-1-one (PO), xanthen-9-one, 7H-benz[de] an-
thracen-7-one (BO). PO and BO can be readily and quickly separated from particulates and
determined.
• Dicarbonyl arenes. Dicarbonyl arenes (quinones) isolated from airborne particulate matter include
naphthoquinone, anthraquinone, anthanthrone, pyrenequinones, and benzpyrene quinones.
• Hydroxy carbonyl arenes. These are ring carbonyl arenes containing hydroxy groups and possibly
aikoxy or acyloxy groups. Hydroxy carbonyl compounds found in particulate matter include
scopoletin and a variety of flavonols. These are derived from biological material and probably would
be found wherever there is natural air pollution.
• Oxa arenes and thia arenes. Oxa arenes contain a ring oxygen atom, while thia arenes contain a ring
sulfur atom. A large assortment of oxygen-containing heterocyclic hydrocarbons are present in the
neutral fraction of airborne particulate matter. Dibenzofuran and dibenzothiophene are examples of
oxa and thia arenes, respectively; both are found in airborne particulate matter, although they are
more common in the vapor phase.
• Polychloro compounds. Among the polychloro compounds found in polluted atmospheres are
polychlorobiphenyls, polychloro-p-terphenyls, chlorodibenzofurans, and chlorodibenzo-p-dioxins.
• Pesticides. A large variety of pesticides are known. Among the few found in the atmosphere are
aldrin, chlordane, and DDT.
POM may be formed in any combustion process involving compounds containing carbon and hydrogen. The
amount formed in a given combustion process is dependent upon the "efficiency" of the process—that is,
completeness of the oxidation of carbon and hydrogen to carbon dioxide and water, respectively. POM is
probably formed in these processes by accretion of carbon-containing free radicals in the reducing
atmosphere existing in the center of the flame. Since POM is formed during combustion, it seems clear that
most POM in the urban atmospheres originates from man-made sources. There are, however, "natural"
sources such as fires set by "natural causes" and possibly decomposition of organic matter.
Much of the POM formed in the course of combustion processes is probably emitted as vapor from the
flame. Some vapor remains in the vaporous phase, but some cools and condenses on particles already
present in the atmosphere or forms small particles of pure condensate. The primary physical properties that
influence the behavior of POM-containing aerosols are particle size, surface area, shape, and density.
Current knowledge of each of these factors is limited.
Available data indicate that PPOM is largely associated with particles less than 5 micrometers (jum) in
diameter. This range includes the sizes that may affect visibility and cloud and precipitation processes, as
well as respiratory intake. One factor that may be important in limiting the size of the smallest particles of
PPOM is the Kelvin effect, which says that the equilibrium vapor pressure varies with the radius of
curvature of the particles and the surface energy of the volatile material.
1-2 PARTICULATE POLYCYCLIC ORGANIC MATTER
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PPOM is subject to the same atmospheric processes as olher types of airborne particles. It is dispersed in the
atmosphere by turbulence and transported by winds. Removal from the atmosphere occurs by
sedimentation, deposition by impaction (on rocks, buildings, and vegetation, for example), washout, and
rainout. The residence time in dry air varies from 4 to 40 days for particles less than 1 /urn in diameter, and
0.4 to 4 days for particles 1 to 10 jum in diameter. The chemical reactivity of PPOM may reduce its half-life
to less than 1 day. The primary reactions that shorten the atmospheric life span of PPOM are
photooxidation and reactions with oxidants or sulfur dioxide.
Most PPOM measurements are for benzo[a]pyrene (BaP). Concentrations recorded by the National Air
Surveillance Networks (NASN) normally are highest during the winter season, apparently because more fuel
is burned then. In areas where PPOM concentrations are high, the seasonal variation in concentration is
quite pronounced. A wide variation is also observed between different urban areas, suggesting a significant
difference in the characteristics of their polluted atmospheres. Early animal experiments carried out with
various organic fractions of airborne particles have shown apparent geographic differences in carcinogenic
activity, with the highest activity in material from Birmingham and the lowest in material from Los
Angeles.
To assess the potential hazards to human health resulting from PPOM in the atmosphere and to make
meaningful decisions regarding the necessity and strategies for control, it is necessary to identify the suspect
substances and their sources, evaluate the collection and measurement techniques, examine the biological
effects, and evaluate the control technology. This report addresses these aspects. A comprehensive review,
published by the National Academy of Sciences in 1972 and entitled "Particulate Polycyclic Organic
Matter," has provided the basis for much of the material presented here; other information gathered from
the literature, however, and results of U.S. Environmental Protection Agency (EPA) research have also
been incorporated.
Introduction 1-3
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2. SUMMARY AND CONCLUSIONS
2.1 SUMMARY
Evidence is now available confirming that a significant difference exists between urban and nonurban
residents in the occurrence of lung cancer and other chronic or latent diseases. The reason for this "urban
factor" is not known, but it is probably due to a number of factors. In American males, the urban lung
cancer death rate is about twice the rural rate, even after adjustment for differences in smoking habits. A
large series of animal experiments carried out with various extracts and fractions of airborne particulates
indicate apparent geographic differences in biological activity, with the highest incidence of cancer being
associated with material from Birmingham, Alabama, and the lowest with material from Los Angeles,
California. This evidence suggests that the pollutant characteristics, and hence the effect upon human
health, may be quite different between specific urban atmospheres.
Experiments have shown a number of polycyclic organic compounds to be carcinogenic in animals.
Although these same compounds have not been proven to be carcinogenic in humans, evidence strongly
suggests that they may contribute to the ''urban factor." There are no known data on teratogenicity of
PPOM, Work on mutagenicity in higher organisms has been limited, and the results are inconclusive.
Early studies on the biologic effects of environmental POM demonstrated its carcinogenicity and focused
subsequent toxicologic laboratory research in that direction. Many screening methods have been devised to
evaluate carcinogenicity. These methods have been applied to pure polycyclic compounds representative of
those found in the environment, as well as to fractions and mixtures of PPOM collected from urban
atmospheres. Inquiries have been made into many of the ramifications of how these compounds reach the
cells in which carcinogenesis occurs, what takes place in these cells at the molecular level, and how these
sequences may be altered. Little attention has been directed at development of methods to evaluate
dose-response relationships which could be applied as criteria for standards.
Polycyclic organic matter (POM) is organic matter that contains two or more ring structures that may or
may not have substituted groups attached to one or more rings. POM includes polycyclic aromatic
hydrocarbons, polycyclic heterocyclics, and various derivatives. POM can be separated in two portions.
Particulate polycyclic organic matter (PPOM) is in solid form at ambient temperatures and is defined as
material collected on a glass fiber filter as specified in the Federal Register (Vol. 36, No. 84, Part II, page
8191 to 8195, April 30, 1971). Vaporous polycyclic organic matter (VPOM), that portion of POM that
passes through the filter, will be covered in a separate document.
PPOM in the atmosphere is produced primarily by incomplete combustion and is thought to be emitted as a
vapor from the flame; when cooled, the vapor rapidly condenses on particles already present in the
atmosphere or it forms small particles of pure condensate. The bulk of PPOM found in the atmosphere is
associated with particles of less than 5 micrometers diameter and hence is respirable. This size range may
affect visibility as well as cloud and precipitation processes. Little is known about particle shape, particle
density, or number density.
The primary man-made sources of PPOM, measured as benzo[a] pyrene, in the atmosphere over the United
States are heat generation—430 metric tons (MT) per year—and open burning of refuse (primarily coal
wastes}—500 MT per year. Emissions from coke production may be as high as 150 MT per year, but coke
emissions estimates are very uncertain. The highest emission factors are for small and intermediate
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liand-stoked coal furnaces. Emissions from mobile sources comprise only a small fraction of the total
nationwide emissions.
The mechanisms for removing PPOM from the atmosphere include dry deposition and precipitation. The
half-life—that is, the time required for half the material to be removed or destroyed—is estimated at
approximately 100 hours under dry conditions, but it may be much shorter. There is evidence that some of
the highly reactive compounds are degraded in the atmosphere by reactions with oxidants and by
photooxidation.
PPOM is commonly measured in total suspended particulates, benzene-solution organics, and as
benzofajpyrene (BaP). Ratios of the three vary widely both in urban and nonurban areas. The bulk of the
available data is in terms of BaP, so this compound has been used as an index of PPOM pollution. Because it
is also known to be extremely carcinogenic to animals, BaP has been used extensively in experimental work.
Average seasonal concentrations of BaP in the ambient atmosphere range from less than 1 nanogram per
cubic meter (ng/m3) in nonurban areas to a maximum of 50 ng/m3 in urban areas. Local, or short period,
concentrations may reach 100 ng/m3. Average annual or seasonal concentrations higher than about 2
ng/m3 are generally confined to urban areas using coal as the primary fuel. There is large variation among
urban areas.
The total suspended particulate (TSP) concentrations in urban atmospheres (measured by High Volume
Sampler) range from 100 to 200 micrograms per cubic meter (/ng/m3). Benzene-soluble organic particles
comprise approximately 8 to 14 percent of the TSP, and BaP approximately 0.01 to 0.2 percent of the
benzene solubles.
Although some work has been done on every level of PPOM interaction with biologic materials, much
remains to be accomplished. In animal experiments using a number of screening methods, many of the
polycyclic aromatic hydrocarbons found in urban atmospheres have been shown to be carcinogenic in
varying degrees. Both pure compounds, as weir as mixtures of POM with inorganic particulates, have been
used. In some cases, the mixtures have been found to be more potent carcinogens than single
compounds—for example, BaP and hematite. Little attention has been given to development of methods to
evaluate dose-response relationships applicable to ambient air.
POM is a natural component of many plants and plant products and is also produced by many plants and
plant products. Evidence indicates that some of the compounds may behave as plant hormones. POM of all
types can be metabolized by soil microorganisms and aquatic forms, particularly those associated with
polluted water. The incidence of human gastric cancer may correlate with ingestion of plants containing
POM.
Since POM is produced primarily by incomplete combustion, control of emissions would logically include
improvement in combustion efficiency, removal at the source, and local ordinances. A considerable effort is
currently under way to develop control techniques and procedures for the control of particulate matter in
the size range less than 2 micrometers. It is expected, although not yet demonstrated, that control of
particulates will significantly reduce PPOM emissions if the control device is uniformly effective throughout
its collection range.
2.2 CONCLUSIONS
The areas of uncertainty about PPOM are often greater than the areas of knowledge-which attests to the
tremendous complexity of the problem. In such an analysis, one quickly becomes keenly aware of the fact
that the polluted atmosphere encompasses an aggregate of constituents that individually or in
combinations, and in varying degrees, may have a deleterious effect on human health and welfare. When the
possible number of combinations is considered, the simple logistics of investigating all individual elements
or compounds make the task essentially insurmountable. In a practical sense, one is constrained to use some
type of parameter or index to make the problem reasonably tractable; however, such an approach
inherently involves a level of risk. In fact, conclusions based upon limited knowledge and data should be
2-2 PARTICULATE POLYCYCLIC ORGANIC MATTER
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considered tentative. In spite of the uncertainties, a number of specific conclusions related to PPOM in the
atmosphere can be drawn with some confidence. These are:
1. There is a significant difference in the occurrence of lung cancer in urban and nonurban residents even
after the contribution of smoking has been factored out. The available evidence indicates, although it has
not yet been quantified, that PPOM contributes to this increase in cancer among individuals living in urban
areas. There also appear to be significant differences between urban areas.
2. Polycyclic aromatic hydrocarbons and heterocyclic compounds constitute a group of known animal
carcinogens that are present in the particulate form in the atmosphere.
3. The carcinogenicity of a mixture of compounds may be greater than the sum of that of the individual
compounds.
4. Compounds present in the atmosphere may act as tumor-inhibitory or anticarcinogenic agents, although
their role is poorly understood at this time.
5. No teratogenic or mutagenic effects have been found in animals, but studies in this area have not been
extensive. One might postulate that urban susceptibility to carcinogens may have been induced by
mutagenic mechanisms over several generations.
6. The evidence clearly shows that occupational exposure to higher-than-urban concentrations of some
polycyclic compounds will increase the incidence of human lung cancer.
7. There is no conclusive evidence that a reduction of benzo[a] pyrene concentration in the ambient
atmosphere would necessarily reduce the occurrence of human lung cancer.
8. Dose-response relationships or threshold values have not been established for PPOM in the ambient
atmosphere.
9. To date, epidemiologic findings implicate POM in the production of skin and lung cancers. Although
most authors cite BaP as the primary human carcinogen, a great deal of work remains in defining the roles
of specific polycyclic compounds in producing human disease.
10. Studies to date have suffered from the inability to characterize local air pollution. A sign of this
inability has been the tendency to ascribe the total carcinogenic air pollution effect to BaP alone. It is
reasonable in many ways to use BaP as an index to air pollution, but PPOM has never been shown to cause
human lung cancer and has never even been associated with skin cancers of any kind. For the present, the
epidemiologist is not justified in making broad generalizations about local findings.
11. The problem of defining the role of PPOM is complicated by the phenomenon of cocarcinogenesis. It
has often been found that even a potent carcinogen is relatively inactive unless coupled with one or more
other substances, or cocarinogens. Furthermore, cocarcinogens can greatly shorten the latent period of
carcinogenesis. Known cocarcinogens include ultraviolet radiation, epoxides, lactones, asbestos, and
aromatic hydrocarbons. Suspected ones include sulfur dioxide, nitrogen oxides, and ozone. Present data do
not warrant intelligent long-range conclusions.
12. There is no documented evidence of deleterious effects of PPOM on materials at ambient levels.
13. The incidence of gastric cancer has been correlated with the ingestion of plant or plant parts containing
POM.
14. POM of all types can be metabolized by soil microorganisms and aquatic forms, particularly those
associated with polluted water.
Summary and Conclusions 2-3
-------
15. PPOM is emitted into the atmosphere primarily from incomplete combustion of fuels. The principal
sources are heat generation, refuse burning, and uncontrolled coke production. All emission factors are
poorly quantified.
16. Few studies have been made on natural emissions of POM. There is some evidence that POM is
produced in the decay of organic matter, although the contribution to ambient concentrations is thought to
be small.
17. Organic matter in the atmosphere is primarily associated with particulars matter.
18. Rapid and reliable techniques are not available for measurement of PPOM at sources and in the
ambient air. Although the use of BaP as an index of PPOM is desirable for some activities, it is not a
universally acceptable approach,
19. Adequate PPOM control techniques are not available currently. It is a general consensus of the Task
Force Panel that control of particulate emissions from combustion sources will significantly reduce the
levels of PPOM in the atmosphere.
2-4 PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
3. EMISSIONS
3.1 INTRODUCTION
Discussions of PPOM emissions invariably center on BaP. This compound is singled out for several reasons:
• Considerable emission data are available from a multitude of sources, and emission data for other
PPOM compounds are sparse by comparison.
• Since PPOM primarily results from incomplete combustion, a control strategy to improve combustion
efficiency will reduce BaP emissions, as well as that of many other PPOM compounds.
• Ambient air data for BaP have been available for several years fromNASN.
• Many publications, particularly during the 1960's, describe biological effects of BaP in animals.
Concern about the potential carcinogenic effect of BaP has stimulated development of a data bank on
the sources of emissions and the ambient air concentrations.
The importance of combustion efficiency on PPOM emissions is illustrated by plotting BaP emission rates
against gross heat input for various coal-fired units (Figure 3-1).1 Because of the many variables affecting
formation of BaP, a wide range of concentrations can be expected from a given size unit. Emissions from
units operating with relatively efficient combustion conditions would be expected to fall near the lower
boundary of the range, whereas emissions from less efficient combustion processes would fall near the
upper boundary. The lower emission rates from the large coal-fired units used by electric power plants can
be attributed to the more efficient combustion of fuel obtainable with closely regulated air-fuel ratios and
uniformly high combustion-chamber temperatures. The highest emission-rate sources are hand-stoked and
underfeed-stoked residential coal-fired heating units.
Comparisons of POM emissions with other products of incomplete combustion indicate that POM emission
rates are generally high when carbon monoxide and total gaseous hydrocarbons are high.2 The correlations
are not consistent enough, however, to warrant their use as a measurement parameter for POM.
In addition to inefficient combustion, another mechanism for the emission of PPOM is vaporization and
aeration of substances that contain PPOM. Examples are coal-tar-pitch waterproofing, asphalt hot-road-mix
production, and asphalt air-blowing operations. In comparison to incomplete combustion, vaporization and
aeration are generally minor sources of PPOM.
3.2 EMISSIONS FROM STATIONARY AND MOBILE SOURCES
Numerous sources were tested for PPOM in the early 1960's as part of a screening program of stationary
and mobile sources by the Federal air pollution control program.1 Ten samples from a variety of source
categories thought to emit PPOM were analyzed for: BaP; pyrene (P)\ benzo [e] pyrene (BeP); perylene
(Per); benzo[ghi] perylene (BghiP); anthanthrene (Anth); coronene (Cor); anthracene (A); phenanthrene
(Phen); and fluoranthene (Fluor). Table 3-1 summarizes the sources.
The largest sources of PPOM emissions for heat generation were coal-fired residential furnaces. Table 3-2
shows that low emissions of BaP were associated with low emissions of other PPOM compounds. The lowest
3-1
-------
O COAL
D OIL
A GAS
< EMISSION LESS
•x THAN VALUE PLOTTED
)TESTS ON SAME
J UNIT
106
107
108 109
GROSS HEAT INPUT TO FURNACE, cal/hr
Figure 3-1. Benzo[a] pyrene emissions from coal, oil, and natural gas heat-generation processes.^
3-2
PARTICIPATE POLYCYCLIC ORGANIC MATTER
-------
emissions in this category were from coal-fired power plants as shown in Table 3-3. BaP emissions from
coal-fired power plants were generally less than 1.6 micrograms per million calories (jug/Meal) compared to
over 1,600 ^g/Mcal for hand-stoked residential furnaces.
Emissions of PPOM from oil- and gas-fired sources were low in comparison to emissions from all coal-fired
sources, as shown in Figure 3-1. Detectable concentrations of BaP were found in only two of the six
oil-fired units tested. The highest concentration was 3.6 jug/Meal. Of the five gas-fired sources tested, BaP
was detected in two. The highest concentration was 1.1 (Ug/McaL The two gas-fired sources where BaP was
detected produced more PPOM than the other three sources, apparently because of improper adjustment of
the air-fuel ratio as evidenced by high concentrations of carbon monoxide and total gaseous hydrocarbons.2
PPOM emissions from commercial and municipal incineration and from open-burning of municipal refuse,
grass clippings, and automobiles are summarized in Table 3-4. Those from petroleum cracking catalyst
regeneration are summarized in Table 3-5. Eight automobiles and four trucks, without emission control
devices, representing two popular vehicle makes, were also tested for PPOM. Results are reported in Table
3-6.
Table 3-1. SOURCES SURVEYED FOR PPOM EMISSIONS1
Source category
Source
Heat generation
Refuse burning
Miscellaneous industrial processes
Petroleum catalytic cracking
catalyst regeneration
Asphalt air-blowing
Asphalt hot-road-mix manufacture
Coke manufacture
Motor vehicle exhaust
Furnaces burning coal, oil, and gas
Municipal and commercial incinerators
Open burning dumps
Fluid catalytic crackers
Thermofor catalytic crackers
Houdriflow catalytic crackers
Gasoline-burning automobiles and trucks
Emissions
3-3
-------
Table 3-2. PPOM EMISSIONS FROM COAL-FIRED RESIDENTIAL FURNACES1
n
C
>
tn
"d
O
f
o
o
H- I
O
O
2
l—^
n
H
tfl
73
Source
1
2
3
4
Firing
method
Under
feed
stokers
Hand-
stoked
Fuel
rate,
kg/hr
2.2
1.9
1.7
2.3
2.0
3.6
2.9
2.5
Gross
heat
input.
Mcal/hr
25
25
25
25
25
25
25
25
Emissions,
jug/Meal heat input
Group 1a
BaP
15
258
321
266
34
1,587
6,746
13,095
Pb ,
31
1,190
754
635
179
2,381
10,714
36,111
BeP
21
155
234
218
31
397
3,452
5,952
Per
31
19
22
2
238
873
1,389
BghiP
2
242
230
234
25
1,190
5,556
8,730
Anth
24
12
5
357
1,071
1,944
Cor
5
16
13
119
194
385
Group 2a
U
Ab
278
190
56
5
2,587
4,365
1 1 ,508
u
PhenD
115
2,421
1,389
675
202
3,968
9,127
29,762
h
Fluor0
187
1,310
595
1,270
302
3,968
17,063
43,651
A blank indicates that the compound was not detected in the sample.
aAnalytical results are more accurate for Group 1 than Group 2.
'-'Minimal values, especially for A and Phen.
-------
Table 3-3. PPOM EMISSIONS FROM COAL-FIRED POWER PLANTS1
Source
1
2
3
4
5
6
Type of unit
Pulverized coal
(vertically fired
dry-bottom furnace)
Pulverized coal
(front-wall-fired.
dry-bottom furnace)
Pulverized coal
(tangentially fired.
dry- bottom furnace)
Pulverized coal
=uel
rate,
MT/hr
59
60
43
41
47
45
57
8
(opposed-, downward- 10
inclined burners;
wet-bottom furnace)
Crushed coal
(cyclone-fired.
wet-bottom furnace)
Spreader stoker
(traveling grate)
8
53
60
8
8
8
Gross
heat
input,
Mcal/hr
388,000
399,000
286,000
275,000
331,000
338,000
344,000
58,000
72,000
60,000
415,000
469,000
59,000
58,000
58,000
Emissions,
jug/Meal heat input
Group 1a
BaP
0.12
0.12
0.25
0.56
0.09
0.11
0.76
0.13
0.02
0.02
2.41
0.56
0.02
<0.01
<0.01
pb
1.16
0.76
1.04
0.32
1.04
0.85
0.76
0.12
0.06
0.04
10.97
1.84
0.06
0.03
0.02
BeP
0.19
0.34
0.29
0.46
0.38
0.12
0.06
4.44
0.81
0.06
Per
0.10
0.38
0.22
BghiP
0.36
0.07
0.81
1.01
0.21
0.14
2.15
0.27
Group 2a
Anth
0.03
Cor
0.04
0.09
0.02
0.01
0.01
0.09
Ab
Phenb
1.04
0.19
Fluorb
1.29
1.19
1.85
0.37
0.83
0.07
2.11
0.19
0.08
0.05
0.72
3.25
0.06
0.03
0.01
o
A blank indicates that the compound was not detected in the sample.
aAnalytical results are more accurate for Group 1 than Group 2.
'-'Minimal values, especially for A and Phen.
-------
OJ
ON
Table 3-4. PPOM EMISSIONS FROM INCINERATION AND OPEN BURNING1
n
c
r
H
W
O
r
n
n
n
O
O
z
h—<
O
2
1
m
Type of unit
Municipal incineration
225 MT/day
multiple chamber
45 MT/day
multiple chamber
Commercial incineration
4. 8 MT/day
single chamber
2.7 MT/day
multiple chamber
Open burning
Municipal refuse
Grass clippings,
leaves, branches
Automobiles
Emissions,
^g/kg of refuse charged
Group 1a
BaP
0.2
0.2
116.7
572.7
330.4
352.4
28,634.4
pb
17.6
4.6
704.8
9,251.1
1,762.1
1,762.1
74,889.9
BeP
0.8
1.3
99.1
572.7
242.3
154.2
14,537.4
Per
6.8
132.2
37.4
2,643.2
BghiP
1.4
198.2
1,916.3
154.2
160.8
19,603.5
Group 2r
Anth
14.5
174.0
26.4
2,202.6
Cor
6.5
1.4
46.3
462.6
2,422.9
Ab
103.5
189.4
3,083.7
Phenb
308.4
130.0
21,365.6
Fluor
21.6
7.3
484.6
8,590.3
1,607.9
1,101.3
52,863.4
A blank indicates that the compound was not detected in the sample.
Analytical results are more accurate for Group 1 than Group 2.
Minimal values, especially for A and Phen.
-------
Table 3.5. PPOM EMISSIONS FROM PETROLEUM CRACKING CATALYST REGENERATION1
Source
1
2
3
4
5
6
I
Type of
unitb
FCC
FCC
HCC
TCC
(Air lift)
TCC
(Air lift)
TCC
(Bucket
lift)
Sampling
point
Regenerator
outlet
CO boiler
outlet
Regenerator
outlet
CO boiler
outlet
Regenerator
outlet
CO boiler
outlet
Regenerator
outlets
Regenerator
outlets
Regenerator
outlets
Process
rate.
m3 /stream
day
3,212
7,354
5,915
3,116
3,625
3,784
2,099
Emissions, /ig/m3 of oil charged3
Group 1C
BaP
277
69
2,893
138
1,289,308
283
754,717
352,201
389,937
195
pd
1,069
547
176,101
1,069
823,899
245
817,610
1,572,327
1,635,220
1,761
BeP
333
132
22,641
113
1,949,685
610
754,717
352,201
471,698
516
Per
213,836
30
62,893
55,346
34,591
BghiP
94
2,642
346
1,886,792
818
452,830
276,730
339,623
Anth
94,340
20
27,673
8,176
11,321
Cor
69,182
50
2,264
Group 2C
Ad
13,208
5,786
50
150,943
62,893
69,182
Phend
2,515,723
1 32,075
522
490,566
2,213,836
2,075,472
j
Fluor"
1,006
453
125,786
535
52,201
145
182,390
69,182
371
o
A blank indicates that the compound was not detected in the sample.
aFresh feed plus recycle.
DFCC: fluid catalytic crackers; TCC: Thermofor catalytic crackers; HCC: Houdriflow catalytic crackers.
"Analytical results are more accurate for Grc
^j Minimal values, especially for A and Phen.
°Analytical results are more accurate for Group 1 than Group 2.
d.
-------
OJ
00
Table 3-6. PPOM EMISSIONS FROM MOTOR VEHICLES1
Vehicle year
Automobiles
Make A 1962
1962
1959
1956
4-car average
Make B 1964
1962
1959
1957
4-car average
Trucks
Make A 1963
1956
2-truck average
Make B 1964
1963
2-truck average
Mileage,
km
30,400
41,600
78,400
92,800
22,400
30,400
84,800
107,200
27,200
80,000
9,600
27,200
Emissions, ,ug/km traveled
Group 1a
BaP
3.8
2.5
1.9
2.5
13.8
5.0
2.5
2.5
6.9
3.1
2.5
6.9
21.3
10.0
>1.6
81.3
>41.3
12.0
7.9
9.0
pb
50.1
43.8
8.1
16.9
74.4
41.9
47.5
41.9
88.8
78.1
36.3
64.4
213.1
97.5
256.3
937.5
600.0
275.0
400.0
331.3
BeP
6.3
5.0
3.1
5.6
15.0
8.1
8.8
6.3
3.8
11.3
20.0
>2.5
65.6
>33.8
24.4
30.0
26.3
Per
<0.3
<0.1
<0.3
<0.6
<0.6
<0.6
1.3
0.6
0.6
1.3
2.5
1.3
0.6
12.5
6.3
1.9
0.6
1.3
BghiP
16.3
21.9
21.3
8.8
48.1
23.8
4.4
5.6
40.6
30.6
17.5
25.6
90.0
37.5
58.8
300.0
181.3
57.5
95.6
67.5
Anth
1.3
0.6
<0.3
<0.3
1.9
0.6
<0.3
<0.3
0.6
3.1
1.3
73.8
36.9
Cor
Group 2a
A"
6.3 j 3.8
6.9
10.6
2.5
20.0
9.4
4.4
5.0
12.5
11.9
5.6
6.9
40.0
16.9
38.1
150
93.8
23.8
63.8
37.5
2.5
2.5
1.3
0.6
0.6
5.0
3.8
2.5
6.9
8.1
4.4
6.3
168.8
87.5
14.4
8.8
10.4
Phenb
16.9
28.8
2.5
6.3
33.1
22.5
57.5
20.0
5.6
30.6
46.9
33.1
162.5
643.8
406.3
212.5
181.3
200.0
Fluorb
24.4
24.4
4.4
24.4
63.8
31.9
26.3
20.0
41.9
40.6
20.0
47.5
139.4
61.3
137.5
612.5
375.0
193.8
275.0
218.8
H
O
H
tfl
"0
O
r
o
h— ^
O
O
&
O
>
HH
O
A blank indicates that the compound was not detected in the sample.
aAnalytical results are more accurate for Group 1 than Group 2.
Minimal values, especially for A and Phen.
-------
The PPOM emissions from an asphalt air-blowing process showed no BaP but did show large concentrations
of lower-molecular-weight PPOM, including 3100 micrograms per cubic meter (jug/m3) of pyrene and 220
/ug/m3 of anthracene.3 The source surveyed operated at a rate of 22 metric tons (MT) of asphalt per hour
with a stack effluent of 521 cubic meters per minute (m3/min) at the point of testing.
An asphalt hot-road-mix plant was tested for PPOM. BaP was detected on the inlet of a water spray tower
but was not detected on the outlet of this control device. Pyrene, anthracene, and fluoranthene were the
only measurable PPOM on the outlet side of the control device. The concentrations were 3, 1.4, and 2.5
/jg/m3 respectively.3 These are minimal concentrations, especially anthracene, since these compounds also
are present in the atmosphere as VPOM. The plant was operated at 120 MT/hr of finished mix with a stack
effluent of 1158 m3/min at the point of testing.
Recently, qualitative test results have been reported for the effluent of 20 coke ovens.4 Because no source
test data were available in the publication, emission rates cannot be determined. The following compounds
were found: fluoranthene, pyrene, benzfa] anthracene, chrysene, benzanthrone, BaP, and benzo[e]
pyrene. Two investigators have measured BaP at various positions in coke oven operations,5 '6 These studies
were not designed specifically to determine emission factors for coke ovens, but the values obtained were
used to estimate emissions from coke ovens. The estimates ranged from 0.05 to 153 MT of BaP per year.
No reliable emissions estimates can be derived from these data.
3.3 STATIONARY AND MOBILE SOURCE EMISSION DATA LIMITATIONS
Table 3-7 reports a BaP emission inventory made by the National Academy of Sciences (NAS). (A more
up-to-date inventory became available as this document went to press. It is presented in the Appendix.)
NAS estimated that 90 percent of the annual nationwide BaP emissions came from three stationary
combustion sources—coal-fired and wood-fired residential furnaces, coal refuse burning, and coke
production.
Residential coal furnaces were the major source of BaP emitting 380 MT/yr. However, the emission factors
used by NAS were based on studies which tested only two hand-stoked and two underfeed-stoked
residential furnaces.1
Coal-fired steam power plants were estimated to emit only 1 MT per year of BaP. All tests, however, were
conducted on conventional type boilers (30 to 40 percent excess combustion air) available during the early
1960's.1'8 To meet EPA's nitrogen oxides standard for new fossil-fuel-fired steam generation plants,
two-stage combustion boilers are viewed as a most promising replacement to conventional type boilers. In
two-stage combustion, the first stage operates below the stoichiometric air requirements for complete
combustion of the fuel. This condition, incomplete combustion, favors formation of POM. In addition,
overall excess combustion air is normally around 10 percent for two-stage combustion of coal. This lower
excess combustion air may result in reduced oxidation of POM in the second stage if this material is formed
in the first stage. No test results are reported in the literature for BaP or other POM from two-stage
combustion.
Wood-burning home fireplaces were estimated by NAS to contribute 36 MT/yr of BaP. This estimate,
however, is speculative, since no firm data were available in the literature.
Enclosed incineration contributes 31 MT/yr and open burning of domestic and municipal wastes 22 MT/yr.
Extensive testing has been conducted on these source types.
NAS listed coal refuse fires at 308 MT/yr. The information was from personal communication, however,
with no reference to published data.7
Emissions 3-9
-------
Table 3-7. ESTIMATED BENZO[a] PYRENE EMISSIONS IN UNITED STATES, 19687'3
Source type
Emissions,
MT/yr
Stationary sources
Coal, hand-stoked and underfeed-stoked
residential furnaces
Coal, intermediate-size furnaces
Coal, steam power plants
Oil, residential through steam power type
Gas, residential through steam power type
Wood, home fireplaces
Enclosed incineration, apartment through
municipal type
Open burning, domestic and municipal
waste
Open burning, coal refuse
Open burning, vehicle disposal
Open burning, forest and agriculture
Petroleum catalytic cracking
Coke production
Asphalt air-blowing
Asphalt hot-road-mix plant
Mobile sources
Gasoline-powered, automobiles and trucks
Diesel-powered, trucks and buses
Rubber tire degradation
Aircraft
Lawn mowers and motorcycles
380
9
1
2
2
36
31
22
308
45
127
5.
0.05 to 153b
20
No estimate
No estimate
Estimated BaP emissions for 1972 are given in the Appendix at the end of the document.
Range of values based upon figures obtained from three separate studies not designed specifically to determine emission
factors from coke ovens.5'6 Original value reported in Reference 7 was 180 MT.
NAS suggested that open burning of vehicles emitted 45 MT/yr of BaP. This level appears high in view of
the fact that States now ban open burning. Furthermore, use of enclosed auto incineration and auto
crushers for preparation and disposal of vehicles should result in lower BaP emissions than suggested by
NAS.
Forest fires and agricultural burning were estimated by NAS to emit 127 MT/yr.7 Using new data from the
US. Forest Service on the extent of forest and agricultural burning, EPA calculated that 9.5 MT per year of
BaP are emitted from these sources.
PPOM emissions from fast service restaurants specializing in charcoal broiling have not been evaluated but
may be significant because broiling results in incomplete combustion (as is apparent from the dense smoke
emissions), the transport distance between the source and receptor is minimal, and a rapid growth has
occurred in the fast-service restaurant business.
3-10
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
Gasoline-powered automobiles and trucks were reported by NAS to emit an estimated 20 MT/yr. This
estimate is based on studies for uncontrolled motor vehicles surveyed before 1964.'>9 NAS indicated
emission control devices on automobiles since 1968 models have reduced BaP emissions by 85 percent,
compared with uncontrolled vehicles surveyed before 1964. Furthermore, large reductions in BaP emissions
should result from control measures instituted to meet hydrocarbon and carbon monoxide standards
scheduled for mid-1970's. Emissions from uncontrolled automobiles (prior to 1964) were 45 /jg per liter of
fuel, versus 5 to 8 for 1968 emission-controlled cars and less than 3 for the advanced systems of the
mid-1970's.
NAS reported no BaP emission data for aircraft. Recent Russian studies on a modern aircraft engine showed
releases into the atmosphere of from 2,000 to 10,000 jug of BaP per minute.10
NAS did not estimate emissions from lawn mowers and motorcycles. NAS data for a two-cycle engine,
however, suggest large BaP emissions-2900 yug per liter of fuel. This source should not be ignored since the
transport distance between source and receptor is short and the emission rate is potentially high.
3.4 REFERENCES
1. Hangebrauck, R. P., D. J. von Lehmden, and J. E. Meeker. Sources of Polynuclear Hydrocarbons in
the Atmosphere. National Air Pollution Control Administration. Durham, N. C. Publication Number
999-AP-33, 1967. 44 p.
2. Hangebrauck, R. P., D. J. von Lehmden, and J. E. Meeker. Emissions of Polynuclear Hydrocarbons and
Other Pollutants from Heat-Generation and Incineration Processes. J. Air Pollut. Contr. Ass. 14:261,
July 1964.
3. von Lehmden, D. J., R- P. Hangebrauck, and J. E. Meeker. Polynuclear Hydrocarbon Emissions from
Selected Industrial Processes. J. Air Pollut. Contr. Ass. 75:306, July 1965.
4. Searl, T. D., F. J. Cassidy, W. H. King, and R. A. Brown. An Analytical Method for Polynuclear
Aromatic Compounds in Coke Oven Effluents by Combined Use of Gas Chromatography and
Ultraviolet Absorption Spectrometry. Anal. Chem. 42:954, August 1970.
5. Smith, W. M. Evaluation of Coke Oven Emissions. (Presented to the 78th General Meeting of the
American Iron and Steel Institute, New York City. May 28-29, 1970.)
6. Masek, V. The Composition of Dusts from Work Sites of Coke Ovens. Staub-Reinhalt. Luft.
50(5):34-37, May 1970. (English translation.)
7. Particulate Fob/cyclic Organic Matter. National Academy of Sciences, Washington, D. C., 1972. 361 p.
8. Cuffe, S. T., R. W. Gerstle, A. A. Orning, and C. H. Schwartz. Air Pollution Emissions from Coal-Fired
Power Plants. (Presented at the Annual Meeting of the Air Pollution Control Association, June 1963.)
9. Begeman, C. R., and J. M. Colucci. Polynuclear Aromatic Hydrocarbon Emissions from Automotive
Engines. Society of Automotive Engineers. New York. Paper 700469. 1970.
10. Shabad, L. M., and G. A. Smimov. Aircraft Engines as a Source of Carcinogenic Pollution of the
Environment - Benzo[a] pyrene Studies. Atmos. Environ. 6:153, 1972.
Emissions 3-11
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4. MEASUREMENT TECHNIQUES
41 INTRODUCTION
This chapter is concerned primarily with measurement of aromatic hydrocarbons (arenes) and their
heterocyclic analogues containing 2 or more rings. Some discussion of polycyclic aza arenes (PAA) as well
as a few other types of PPOM and VPOM is included. This chapter reviews and comments on methods from
the viewpoint of an EPA scientist experienced in the field. More detailed information is provided by the
National Academy of Sciences' review and a selected list of references.2"6
4.2 PROPERTIES AFFECTING THE MEASUREMENT OF POM
42.1 Boiling Point
The organic material in the atmosphere can be subdivided into gases, vapors, and particles mainly on the
basis of volatility. Thus, material that is a liquid or solid on the laboratory shelf at room temperature and
pressure but a gas in the atmosphere is classified as a vapor. PPOM is collected on filters, while VPOM is
collected by methods more suitable for lower boiling materials. On this basis, some material is part vapor
and part particulate; the equilibrium is affected by temperature and the collection media. Airborne
particulate matter is by definition the material collected on standard glass fiber filters with a standard High
Volume sampler as specified in the Federal Register (Vol. 36, No. 84, Part II, pages 8191-8195, April 30,
1971).
Separation is another factor affected by the volatility of POM. In gas chromatography, for example,
separation of compounds of similar polarity is based mainly on differences in their volatility. Consequently,
compounds that have similar boiling or sublimation points are hard to separate—for example, chrysene from
benzfa] anthracene and benzo[a]pyrene from benzo[e] pyrene. In addition, some spots on thin layer
chromatography chromatograms can volatilize if left too long—pyrene, for example.
4.2.2 Solubility
Differences in solubility of the POM family from other types of compounds in various solvents can be used
to concentrate the POM. This property is also used in selectively extracting POM from particulates.
4.2.3 Reactivity to Oxidants in the Presence of Light
Polycyclic aromatic hydrocarbon (PAH) compounds containing a linear structure are more readily oxidized
than those without such a structure. Therefore, hydrocarbons such as tetracene and pentacene are usually
not found in the atmosphere, although angular compounds such as benzfa] anthracene and chrysene are.
The stability of PAH suspended in the atmosphere depends on molecular structure, the amount of available
light, and the presence of oxidizing pollutants. For example, half-lives of less than a day to several days
have been given for BaP on soot in sunlight. However, BaP within the soot particle would probably have a
much longer half-life. The smaller PAH would disappear from soot in sunlight at a more rapid rate than the
larger ones. Summer temperatures would accelerate this loss.
4-1
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42.4 Stability
The stability of PAH collected on a glass fiber filter has been studied. No tetracyclic and larger PAH were
lost with 2 hours of collection at 1.2 cubic meters per minute (m3/min) followed by 2 hours of filtered air
at 1.2 m3/min drawn through the sample. Some tetracyclic PAH, but no larger PAH, were lost with 24
hours of collection followed by 24 hours of treatment with filtered air. Even when air was pulled through
the filter for 3 weeks, the pentacyclic and larger PAH showed little, if any, loss.
PAH collected on glass fiber filter paper are stable for at least 3 weeks if they are pentacyclic or larger. The
concentrations of tricyclic and tetracyclic PAH decrease under these conditions. Periods of filter storage
longer than 3 weeks are not advisable.
The residue obtained from extraction of the filter and careful evaporation to dryness is stable for at least 6
years if kept at 5°C and in the dark.
The stability of PAH on an adsorbent is strongly affected by the type of adsorbent and by the length of
exposure to light Ultraviolet light can accelerate the decomposition. On some adsorbents, some PAH can
decompose within a few minutes under ultraviolet light; with other adsorbents much longer exposure is
necessary. For this reason, yellow plastic sheeting, which filters out light less than 400 nanometers in
wavelength, is used over any source of light during thin layer chiomatographic analysis of PAH.
43 COLLECTION
High-volume filtration samplers are used routinely to collect atmospheric particulate matter on fiber glass
filters for periods of 24 hours or more. This type of sampling is adequate for determining the concentration
of PPOM and of individual polycyclic compounds. The collection and retention of some compounds of
POM in this manner will be affected by temperature, air flow rate, and particulate composition.
44 INTERFACIAL TECHNIQUES
44.1 Extraction
Extraction of the PAH from particulates is usually accomplished by a 5- to 8-hour Soxhlet extraction with
benzene or cyclohexane at the boiling point. A more efficient and simpler procedure is to extract the filter
ultrasonically at room temperature for about 15 minutes; in this procedure, polycyclic aromatic
compounds can decompose. If care is not used in the evaporation of the solvent, extensive decomposition
can occur.
4.4.2 Sublimation
PAH can be sublimed off the filters, collected, and analyzed; or it can be sublimed into a gas
chromatograph, separated, and analyzed. A piece of the filter can be used or it can be shredded into fine
particles ultrasonically or with a Wiley mill.
44.3 Direct Assay
An effluent in the vapor form can be separated on a gas chromatograph (without a collection step) and
assayed in the gas phase using a fluorescence detector and/or a mass spectrometer-computer system.
Fluorescence detectors are available for gas phase and liquid phase, but the interfacings need to be
developed and improved. Another problem to be resolved is the incomplete separation of some of the PAH.
4-2 PARTICULATE POLYCYCLIC ORGANIC MATTER
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45 SEPARATION
Because of the large quantity of POM compounds present in urban airborne particles, separation methods
are necessary. In the evolution of methods, the survival of any separation technique is dependent on ease of
handling, separation time, improved recovery, and reliability of the procedure. Cost factors require the
investigation of inexpensive separation methodology.
45.1 Liquid-Liquid Extraction
45.7.7./M//-Liquid-liquid extraction has been used to concentrate the PAH and separate them from
interfering groups. Pure solvents and hydrocarbon standards must be used. The PAH can be separated from
the aliphatic hydrocarbons by distribution of the organic particulates between cyclohexane and
nitromethane (or dimethylsulfoxide or dimethylformamide), hexane and dimethylformamide (or dimethyl-
sulfoxide), acetonitrile and hexane, or nitromethane and carbon disulfide. PAH can be separated from
aliphatic hydrocarbons and the polar molecules by distribution of the organic extract between cyclohexane
and dimethylformamide (or dimethylsulfoxide) and back-extraction from the latter layer with cyclohexane
after addition of water.
4.5.1.2 Aza Arctics—The basic fraction containing a number of aza arenes is obtained by extracting an
ether solution of the organic particulates with 20 percent aqueous sulfuric acid, neutralizing this latter
solution with solid sodium carbonate, and extracting this mixture with chloroform.
45.2 Column Chromatography
4.5.2.1 PAH— Column chromatography is probably the best preliminary method for separating an unknown
mixture so as to ascertain its composition in terms of PAH. The method has been in use for the past 20
years. Unfortunately, 12 to 24 hours are necessary for a separation. With the help of thin layer
chromatography, absorption spectrophotometry, and spectrophotofluorimetry, a large number of arenes
can be characterized. The weaknesses lie in the extended period of time necessary for such an investigation
and the difficulty of identifying the alkyl derivatives.
4.5.2.2 Aza Arenes-Molecular characteristics of aza arenes useful in their separation are: (1) the size,
shape, and steric property of the molecule, and (2) the polar effect of the structure on the capability of the
ring nitrogen to bind to the adsorbent and to the eluting solvents. Thus, isomers such as the
benzoquinolines, the benzacridines, and the dibenzacridines are readily separated from each other.
45.3 Paper Chromatography
Paper chromatography has been used in the past, but because it takes many hours for a separation, it is
rarely used in routine assay of POM.
45.4 Instant Thin Layer Chromatography
Instant thin layer chromatography, a form of paper chromatography that permits fast separations, is
primarily used in the analysis of benzanthrone and phenalenone. In 18 minutes, these compounds are
readily separated from the many thousands of pollutants in organic particulates on glass fiber paper
impregnated with silica gel. If necessary, a crude estimation of these compounds can be accomplished by
visual comparision with standards. Otherwise, assay involves elution and fluorimetric estimation.
45.5 Thin Layer Chromatography
A large number of separations of POM are possible with thin layer chromatography (TLC).7 With the help
of spectrophotometric and fluorometric techniques, a large variety of POM assays are available. With two
different types of adsorbents on a plate, two widely differing types of separation are possible. Thus, it is
Measurement Techniques 4-3
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possible with such a plate to separate BaP and other penta- and hexa-cyclic arenas from each other. As yet
gas chromatography cannot do this. The problem is that good technique is necessary, and routine assays of
a large number of samples for PAH would be difficult. Direct examination of the spots with fluorescence
scanners might solve the problem, however.
45.6 High Pressure Liquid Chromatography
Much better separation of pentacyclic and large PAH is obtained with the high pressure liquid
chromotography than with gas chromatography. Separation can be completed in 15 to 30 minutes.
Although standard PAH have been separated, the technique has not yet been applied successfully to
ambient air particulates. This type of separation should be possible for the proper cleanup of the sample.
The method has also been used successfully to separate standard mixtures of aza arenes.
4.5.7 Gas Chromatography
4.5.7.1 PAH-The gas chromatography (GC) system is superior for separating VPOM and, when allied with
ultraviolet absorption spectrophotometry or some form of mass spectrometry, could evolve into one of the
better state-of-the-art separation methods for the PPOM. Although some fine GC separations have been
reported, difficulties have arisen in attempting to use these procedures routinely. Thus far, no satisfactorily
proven method is available to separate benzo[a]pyrene from benzo[e]pyrene and chrysene from
benz [a] anthracene.
For the near future, the best system for routine separation consists of column chromatographic cleanup of
the organic particulates and then GC followed by ultraviolet spectrophotometric assay.
4.5.7.2 Aza Arenes—A. few methods are available for the separation of standard aza arenes. Some work has
been done with programmed temperature and coated high resolution glass capillary columns. About a
dozen aza arenes were identified in ambient air particles by this technique.
45.8 Temperature Programming
Using a gas chromatograph with temperature programming from 20 to 400°C and a high resolution mass
spectrometer interfaced with a digital computer, qualitative and quantitative results (in /ug/m3) can be
obtained for a large number of pollutants in a short period of time. The VPOM and PPOM identified by this
method in atmospheric aerosols are listed in Table 4-1. Although this is a good beginning, no data are
available on the reliability of the identification and quantitative results.
Table 4-1. POM IDENTIFIED IN COLLECTED POLLUTANTS BY MEANS
OF TEMPERATURE PROGRAMMING AND MASS SPECTROMETRY
Naphthalene
Methyl naphthalene
2,3-Dimethylnaphthalene
Tri me thy (naphthalene
Acenaphthene
Anthracene
Phenanthrene
Fluoranthene
Pyrene
Benzo [c] phenanthrene
Benz[a] anthracene
Chrysene
Benzo [a] pyrene
Perylene
Benzo[ghi] perylene
Dibenz[a,h] anthracene
Coronene
Acridine
Benzo [fjquinoline
Carbazole
2,6-Naphthoquinone
9,10-Anthraquinone
9-Xanthenone
4-4 PARTICULATE POLYCYCLIC ORGANIC MATTER
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46 ANALYSIS
A decrease in the total analysis time and an improvement in sensitivity and accuracy have been the criteria
in the evolution of the methodology and instrumentation for the determination of POM. Cost also plays an
important role, however. The objective has been to develop simple, inexpensive methods of estimation as
well as sophisticated, more accurate methods. The various types of separation methods described previously
have been used by themselves or in combinations and with individual measuring methods described in this
section. Many of the methods discussed below are reviewed in a paper by Sawicki.8
Pure standards of POM are needed for all analytical methods. For calibration, it is necessary to run recovery
experiments and/or use an internal standard. In recovery experiments, the pure-standard compound is
added to the mixture as close to the first stage as possible. Internal standard compounds that do not
interfere in the analysis are added to the mixture and assayed with the POM. For PAH analysis, s-triphenyl
benzene or a PAH containing carbon-14 can be used as an internal standard, especially in gas
chromatography.
4.6.1 Polynuclear Aromatic Hydrocarbons
4.6.1.1 Ultraviolet Spectrophotometry—Tbe method that has been used most frequently in the routine
analysis for PAH consists of column chromatography followed by ultraviolet-visible absorption spectro-
scopic scanning of the fractions to permit characterization and assay. This procedure, accompanied by thin
layer chromatography and spectrophotofluorimetry, is probably the best way to initiate a study of
unknown mixtures for PAH. Although this method takes too much time for routine analysis, it can be used
following GC separation to analyze the GC fractions for the individual PAH. The best separations can
probably be achieved by column chromatography with long columns; however, the time of separation is
increased.
4.6.1.2 Spectrophotofluorimetry—This method can be used after column chromatographic, gas chroma-
tographic, and two-dimensional thin layer chromatographic separations.9 Care must be exercised to
minimize quenching phenomena, intensity enhancement, and excimer formation-especially on dry
chromatograms.
The Shopl'skii procedure, which has been used extensively in the USSR, consists of column chroma-
tography followed by fluorescence analysis at low temperatures. Internal reference standards are used for
the determination of individual PAH's. The present method is long and tedious and could be improved.
Another method that has been used consists of two-dimensional TLC followed by direct fluorimetric
scanning. This procedure can be automated.
4.6.1.3 Direct Fluorimetry-This procedure involves drawing the air samples through a liquid bubbler
followed by fluorescence assay of the liquid in terms of anthracene. The main problem in using this crude
method is the effect of the various components of the mixture on the intensity and wavelength positions of
the characteristic emission bands. A fluorescence detector can be used in the gas or liquid phase to obtain
total PAH values. A wide range of sensitivities for different PAH is also available. Such a detector has been
used in the direct gas phase analysis of automotive exhaust for total PAH.
4.6.1.4 High Pressure Liquid Chromatography-High pressure liquid chromatography (HPLC) has high
potential, especially with cleanup of the sample followed by HPLC using an ultraviolet or fluorescence
detector. With automated procedures for spectral scanning and assay of the fractions, HPLC could be
developed into a fast routine method.
4.6.1.5 Gas Chromatography-Probably the best state-of-the-art routine technique, which could be
developed within 6 months, would involve sample cleanup, followed by GC and ultraviolet spectral assay of
Measurement Techniques 4-5
-------
the GC fractions. The simplest method would be temperature programming, or controlled sublimation of
the particulate fraction into a gas chromatograph for direct assay.
Several available methods employ procedures for extracting the organic material from the particles followed
by a preliminary cleanup of this material and GC analysis. Because of the conflicting claims made by
various investigators, these methods need to be evaluated impartially before they are adopted as routine
techniques.
4.6.1.6 Mass Spectrometry—Many variations of mass spectrometry (MS) are used in the analysis of PAH. A
large amount of data can be obtained.10 The GC-MS method has been used in the analysis of VPOM and
PPOM in cigarette smoke and in airborne particles. Many POM compounds have been characterized in the
fractions from the column chromatographic analysis of extracts of organic particulates with the help of
hjgh resolution mass spectrometry.
One procedure involves TLC followed by MS. Using internal standards and an integrated ion current
technique, the detection limit was reported to be 0.05 picogram (pg) of BaP, 0.01 pg of benzo[ghi]-
perylene, and 0.01 pgof coronene.
With the help of internal standards and a controlled evaparation rate, an organic particulate fraction can be
analyzed directly for the PAH content. With this procedure, the PAH in a sample can be determined within
10 minutes with sensitivity as low as 0.5 ng.
The various types of mass spectrometric techniques should be evaluated in the analysis of VPOM and PPOM
— for example, chemical ionization MS, field ionization MS, and field desorption MS.
4.6.1.7 Flame Ionization Defector—When properly used, the flame ionization technique should produce
accurate total PAH values; however, the sensitivity may vary for different compounds.
4.6.1.8 Discussion—Liquid chromatography, gas chromatography, and mass spectrometry are evolving
rapidly. They are the hope of the future in terms of sophisticated automated measurements. It is possible
that with mass spectrometry, in particular, a large amount of data can be made available. EPA has access to
mass spectral signatures of about 15,000 organic compounds, several of which are in the PPOM group.
4.6.2 Behzo[a]pyrene
Some form of separation is necessary before BaP can be determined. Some of the measuring techniques are
discussed here.
4.6.2.1 Ultraviolet Spectrophotometry-Probably the best characterization method for BaP consists of
alumina column chromatographic separation of the pentane-ether extracts followed by an absorption
spectral scan of its ultraviolet spectrum in pentane. In this solvent, BaP shows a highly distinctive triplet at
377, 379, and 382 nm. No other hydrocarbon gives this triplet in pentane.
Separation by sublimation, column chromatography, thin layer chromatography, or gas chromatography
can be used preliminary to analysis. With proper cleanup, a high pressure liquid chromatographic procedure
for BaP could be developed.
4.6.2.2 Room Temperature Fluorimetry-Th\s method of analysis is approximately 100 to 1000 times
more sensitive than the ultraviolet spectral method and provides a high order of selectivity for BaP. One
disadvantage is that invalid results from unrecognized quenching effects could be obtained. This could
affect the position and intensity of fluorescence emission bands used in characterization and assay.
Separation procedures used preliminary to analysis include liquid-liquid extraction, column chroma-
tography, TLC sublimation, and GC. One of the most sensitive methods consists of TLC followed by
4-6 PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
elution and fluorimetric analysis of a sulfuric acid solution of the benzpyrene fraction. Probably the best
separation method for BaP consists of two-dimensional TLC on alumina-cellulose acetate. BaP is separated
from all other hydrocarbons and can be eluted and analyzed fluorimetrically as the neutral compound or as
the cationic salt. At least 20 ;ug of a benzene-soluble fraction would be necessary; the lower limit of
detection would be about 10 ng of BaP.
4.6.2.3 Low Temperature Fluorimetry-Following any of the separation methods described previously,
BaP could be analyzed by low temperature fluorimetry. Since the bands would be much more intense and
much narrower, the analysis would be much more sensitive and highly selective. A disadvantage is that the
liquid nitrogen is required.
4.6.2.4 Shopl'skii Effects-ln Shopl'skii procedure, quasilinear spectra are obtained from frozen crystalline
solutions wherein the dimension of the solute molecule is approximately equal to that of the solvent
molecule. BaP with a molecular length of 1.0 nm gives its sharpest spectrum in n-heptane (1.0 nm). For
example, pyrene in methylcyclopentane has several bands at room temperature - 70 lines at 88° and 120
lines at 9°K. An internal standard must be used in the method, and only the best separation techniques
should be used. Increased sensitivity and selectivity are obtained with the method, but very low
temperatures are required.
4.6.2.5 Direct Spectrophotofluorimetry-A.ftet one- or two-dimensional TLC, BaP can be assayed directly
on the plate by direct spectrophotofluorimetry. This is a convenient method of characterization and assay.
4.6.2.6 High Pressure Liquid Chromatography-This method could be used as a fast survey method for BaP
after proper cleanup.
4.6.2.7 Gas Chromatography—A method of assay involving either sublimation or ultrasonic extraction
followed by gas chromatography should be developed.
4.6.2.8 Mass Spectrometry-Tlus method of assay could be used following any of the methods of
separation previously described, but it would be too expensive to be used for the analysis of BaP.
4.6.2.9 Colorimetry-The method employs a piperonal test on the nonpolar organic fraction of airborne
particles. A fairly good correlation has been obtained between the piperonal value and the BaP
concentration in a large number of samples. The main disadvantage of the method is the use of highly
corrosive trifluoroacetic acid.
4.6.3 PolycycHc Aza Arenes
Probably the best way to examine an unknown mixture for polycyclic aza arenes (PAA) is to isolate the
basic fraction, chromatograph it through an alumina column, scan each fraction spectrally from 200 to 500
nm, quantitate by the base-line method, separate each fraction by TLC, and scan each spot fluorimetrically
before and after elution and before and after addition of acid.
Estimation of PAA is by alumina column chromatography UV-visible absorption spectrophotometry, or
by gas chromatography. Pure standards have to be used throughout these procedures. When standards are
not available, analysis is impossible.
Some of the individual PAA are readily assayed by TLC-fluorimetry using fluorescence-quenching methods
to eliminate the fluorescence of interferences.
46.4 Monocarbonyl Arenes
Both TLC and instant TLC methods have been used to analyze monocarbonyl arenes fluorimetrically. At
least 15 ng of the organic particulate fraction is necessary for the analysis of phenalenone and
benzanthrone; the detection limit is about 20 ng phenalenone and 10 ng benzanthrone.
Measurement Techniques 4-7
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46.5 Residue Analysis
In all analytical methods, blanks should be run routinely. Benzene should be reagent grade and redistilled.
PAH is not normally found in the routinely purified solvents, however, in fluorescence methods of analysis,
impurities will affect results. Therefore, glass distilled solvents must be used in this type of analysis.
46.6 Precision and Accuracy
No universally acceptable quantitative values are available for the precision and accuracy of measurement
techniques for POM. A limited discussion of the precision and accuracy of some of the methods treated
here is given in the Intersociety Committee Manual.11 For example, based upon 11 determinations using
560 ^tg BaP/g extract, the relative standard deviation was calculated to be ±7 percent. The elution of pure
BaP from activated alumina was 95 percent (±5 percent) efficient based upon more than 20 determinations.
Unfortunately these limited data do not provide a realistic basis for conclusions regarding the accuracy of
ambient atmospheric measurements. Accuracy data reported in the literature are usually based upon the
recovery of added material or the recovery of an added radioactive standard. However, this is no guarantee
that what is found in the test mixture is representative of what was in the ambient atmosphere. The
accuracy of ambient air measurements is highly dependent upon collection techniques and instrument
efficiency as well as analytical methodology. Accuracy of measurement also may vary with different POM
compounds. Consequently, it is not necessarily meaningful to talk about the accuracy of ambient air data.
It is perhaps more meaningful to view the program in terms of relative precision and sensitivity, although
this also has not been well established. It seems to be a rather general consensus among those actively
engaged in ambient measurements that a sensitivity of ±0.1 ng/m3 and a relative precision within ±25
percent are reasonable values for concentrations well within the range of detectability. One may be
reasonably confident in using published ambient air data on POM in categorizing the concentration values
as high, medium, or low. In a practical sense, this is the way the data are used. It is questionable, however,
whether one would be justified in using the data to evaluate second order terms in sophisticated
mathematical models involving kinetics or atmospheric transport.
47 REFERENCES
1. Particulate Polycyclic Organic Matter. National Academy of Sciences. Washington, D.C. 1972. Chapters
2-5 and Appendix A-C.
2. Tentative Method of Analysis for Polynuclear Aromatic Hydrocarbon Content of Atmospheric
Particulate Matter. Health Lab. Sci. 7(Suppl.):31-44, 1970.
3. Tentative Method of Analysis for Suspended Particulate Matter in the Atmosphere (High-Volume
Method). Health Lab. Sci. 7:279-286, 1970.
4. Tentative Method of Chromatographic Analysis for Benzo [a] pyrene and Benzo [k] fluoranthene in
Atmospheric Particulate Matter. Health Lab. Sci. 7(Suppl.):60-67, 1970.
5. Tentative Method of Microanalysis for Benzo [a] pyrene in Airborne Particulates and Source Effluents.
Health Lab. Sci. 7(SuppL):56-59, 1970.
6. Tentative Method of Routine Analysis for Polynuclear Aromatic Hydrocarbon Content of Atmospheric
Particulate Matter. Health Lab. Sci. 7(Suppl.):45-55, 1970.
7. Sawicki, C. R., and E. Sawicki. Thin-Layer Chromatography in Air Pollution Research, Vol. 3. In:
Progress in Tliin-Layer Chromatography and Related Methods. A. Niederineser and G. Pataki (ed.).
Ann Arbor, Mich., Ann Arbor Science Publishers, Inc., 1972. p. 233-293.
4-8 PARTICULATE POLYCYCLIC ORGANIC MATTER
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8. Sawicki, E. Analysis for Aerotoxicants. CRC Critical Reviews in Analytical Chemistry. November
1970. p. 275-333.
9. Sawicki, E. Fluorescence Analysis in Air Pollution Research. Talanta. 16:1231-1266, 1969.
10. Safe, N. S., and 0. Hutzinger. Mass Spectrometry of Pesticides and Pollutants. Cleveland, CRC Press,
1973. p. 77-86.
11. Methods of Air Sampling and Analysis. Washington, B.C., American Public Health Association, 1972.
Measurement Techniques 4-9
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5. CONCENTRATIONS IN AMBIENT AIR
5.1 INTRODUCTION
In 1961 Sawicki and co-workers compiled a list of some 60 polycyclic organic compounds identified as
either being present in the air or as emitted to the air from a few familiar sources. This list, partially
updated during preparation of this document by the addition of several aza heterocyclics and other
compounds, is presented in Table 5-1. The potential carcinogenicity of a compound is indicated if so
reported in the Public Health Service survey of organic compounds for carcinogenicity.2 A thorough search
of recent literature would probably provide sufficient newly identified compounds to double the length of
the list. As presented, this list of almost 100 compounds is adequate to illustrate the complexity of PPOM
and define the enormous effort required to bring order out of the existing state of chaos. The problems of
accuracy in measurement as discussed in section 4.6.6 are a further complication that must be considered.
5.2 EARLY MEASUREMENTS OF AMBIENT PARTICULATE POLYCYCLIC ARO-
MATIC HYDROCARBONS
The first large-scale attempt to measure ambient air concentrations of PAH was made by Sawicki and
co-workers3 who conducted two studies of BaP content. One involved the analysis of samples collected
from January through March 1959 at 94 urban and 28 nonurban NASN sampling stations. None of its
results is presented here because of its preliminary nature and short period covered.
Table 5-1. POLYCYCLIC COMPOUNDS FOUND IN AIR, CIGARETTE SMOKE, AND
EXHAUST GASES1'2
Compound
Naphthalene
2-Methylnaphthalene
Alkylnaphthalenes
Azulene
Acenaphthene
Acenaphthylene
Dibenzofuran
Carbazole
Dibenzothiophene
Fluorene
Anthracene (A)
Phenanthrene
2-Methy (anthracene
11H-Benzo[b]fluorene
11H-Benzo[a] fluorene
7H-Benzo[c] fluorene
Fluoranthene (Fluor)
8-Methylfluoranthene
Alkyl fluoranthene
Occurrence3
A T
A T
A
A T
A T
A T
A
A
A
A T
A T
A T
T
A
A T
A
A T
T
T
5-1
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Table 5-1. (continued). POLYCYCLIC COMPOUNDS FOUND IN AIR, CIGARETTE SMOKE, AND
EXHAUST GASES1-2
Compound
Naphthacene
Benz[ a] anthracene (BaA)b'c
Chrysene (Ch)b'°
Alkyl chrysene
Benzofc] phenanthrene0
Pyrene (P)b
1-Methylpyrene
4-Methylpyrene
2, 7-Dimethylpyrene
Naphtho[2,1,8,7-klmn]xanthene
10, 11-Dihydro-9 H-benzo [a] cyclopent[i] anthracene
2, 3-Dihydro-1-H-benzo[a] cyclopent[h] anthracene
7H-Dibenzo[c,g]carbazolec
Benzo[b] fluoranthenec
Benzo[ghi] fluoranthene
Benzo[j] fluoranthene0
Benzo[k] fluoranthene (BkF)b
2-Methylfluoranthenec
Methylfluoranthene
Benzo[a] naphthacene
Dibenzo[b,h] phenanthrene
Dibenz[a,h] anthracene0
Benzo[a] pyrene (BaP)b>c
Methylbenzo[a] pyrene
Hydroxybenzo[a] pyrene
Benzo[a] pyrenequinone
Benzo[e] pyrene (BeP)b'c
Perylene (Per)
Dibenzo[a,1] naphthacene
Dibenzo[a,j] naphthacene
Naphtho[2,1,8-qra] naphthacene (Naphtho[2,3-a] pyrene)b
Phenalen-1-one
Dibenzo[a,i] pyrenec
Dibenzo[a,e] pyrene
Dibenzo[cd,jk] pyrene (anthanthrene)
Dibenzo[cd,jk] pyrene-6, 12-dione (anthanthrone)
Benzotghi] perylene (BghiP)b
Dibenzo[b,pqr] perylene
Coronene (Cor)
Dibenzo[a,h] pyrenec
Tribenzo[a,i] fluorene
13H-Dibenzo[a,i]fluorene
Dibenzo[a,c] naphthacene
Benzo[h] quinoline
Ra-Benzo[h] quinoline
Rb-Benzo[h] quinoline
Benz[c]acridine
Ra-Benz[c] acridine
Rb-Benz[c] acridine
Dibenz[a,h] acridine0
Occurrence3
G
A T
A T
T
T
A T G D
A T
T
A
T
T
T
T
A T G D
A T
A T
A T G D
T
T
T
T G D
T.
A T G D
T
T
A
A T
A T
A G D
T
T
A
A T
T G D
A T G D
A
A T G D
G
A T
A T
T
T
T
A
A
A
A G
A
A
A T
5-2
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
Table 5-1. (continued). POLYCYCLIC COMPOUNDS FOUND IN AIR, CIGARETTE SMOKE, AND
EXHAUST GASES1'2
Compound
Occurrence3
ldeno[1,2,3-ij] isoquinoline
Phenanthridine
11H-lndeno[1,2-b]quinoline
Acridine
Benzoff] quinoline
Ra-Benzo[f] quinoline
Rt>Benzo[f] quinoline
Benz[a] acridine
Rb-Benz[a] acridine
Dibenz [a,j] acridine0
Rb-Dibenz[a,j] acridine
7H-Benz[de] anthracen-7-one
lndeno[1,2,3,-cd] pyrenec
Dibenz[e,1] pyrene0
Xanthene-9-one
Dibenz[a,i] acridine
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A
A: air; T: tobacco smoke; G: gasoline exhaust; D: diesel exhaust.
Abbreviations used for most common compounds in ( ).
Reported by PHS to have carcinogenic activity.
R-alkyl groups: substituted alkyl groups; Ra and Rb: various substitutes.
The other study was more intensive; monthly composite samples from several different sites in nine cities
collected from July 1958 through June 1959 were analyzed in detail.
The monthly average BaP concentration for each city for the 12-month period is shown in Table 5-2.
Except for New Orleans, the highest concentrations of BaP were found during the colder months. The
greatest ranges in concentrations from winter to summer occurred in the coal-burning or heavily
industrialized cities of Birmingham and Nashville.
Data for ambient concentrations of eight different PAH compounds for the winter (January and February)
and summer (July) for seven of the nine cities are given in Table 5-3. There was a distinct contrast between
winter and summer concentrations, with summer concentrations generally considerably lower. The New
Orleans data appeared anomalous for some of the compounds, although at best only rough comparisons can
be made on the basis of a single month's data for each season.
5.3 ROUTINE MEASUREMENTS OF BaP ON SUSPENDED PARTICULATE MATTER
COLLECTED BY NASN
For several years, the benzene-soluble organics (BSO) of quarterly composite samples of suspended
particulate matter collected by the approximately 250 NASN stations have been analyzed for BaP. Data for
urban stations are listed in Table 5-4 and for nonurban stations in Table 5-5.4'5 The data, in the form of
annual arithmetric averages, are listed only for years with four quarters of valid data. Thus the values are as
representative as possible of the entire year.
Concentrations in Ambient Air 5-3
-------
Table 5-2. BENZO [a] PYRENE CONTENT OF THE AIR OF SELECTED CITIES3
(ng/m3)
H
o
C
>
W
T3
O
•<
o
o
r
o
O
I
2
3
w
City
Atlanta
Birmingham
Cincinnati
Detroit
Los Angeles
Nashville
New Orleans
Philadelphia
San Francisco
1958
July
1.6
6.4
3.9
6.0
0.5
1.4
2.0
3.5
0.25
Aug
4.0
6.1
1.3
4.1
0.4
-
4.1
1.9a
0.38
Sept
4.0
10
2.5
-
1.2
6.6
4.1
3.6
1.1
Oct
-
20
15
18
1.2
30
3.9
7.1
Nov
15
34
14
19
4.1
55
3.6
12
3.0
Dec
12
74
18
20
13
40
3.9
12
7.5
1959
Jan
9.9
34
18
28
6.6
25
6.0
8.8
2.3
Feb
7.4
25
18
31
5.3
-
4.1
6.4
2.4
Mar
2.1
23
26
16
1.1
-
2.6
6.4
1.3
Apr
2.1
18
-
12
0.5
9.0
3.3
-
0.8
May
-
5.9
2.0
7.4
0.8
3.4
5.6
3.4
0.8
June
3.6
6.3
2.1
3.4
0.8
2.1
2.6
2.5
0.9
Corrected value based on Figure 3 of reference 3 and comments by the senior author of reference 3.
-------
Table 5-3. POLYCYCLIC AROMATIC COMPOUNDS IN THE AIR OF SELECTED CITIES1
(ng/m3)
City
Winter 1959
Atlanta
Birmingham
Detroit
Los Angeles
Nashville
New Orleans
San Francisco
Summer 1958
Atlanta
Birmingham
Detroit
Los Angeles
Nashville
New Orleans
San Francisco
BghiP
8.9
18
33
18
17
7.3
7.5
5.1
as
9.5
2.3
3.4
4.6
26
BaP
7.4
25
31
5.3
25
4.1
23
1.6
6.4
6.0
0.5
1.4
20
0.3
BeP
4.7
10
23
8.1
14
6.4
2.9
1.5
5.9
5.3
0.6
1.2
3.1
0.5
BkF
6.0
13
20
5.7
15
3.9
1.7
1.3
4.6
4.9
0.5
1.0
1.8
0.2
P
6.0
17
36
6.0
30
23
1.9
0.7
2.1
2.8
0.3
0.6
0.3
0.1
Cor
4.3
3.5
6.4
12
4.6
27
4.9
25
2.4
1.8
2.2
1.3
2.5
1.6
Per
1.1
5.5
6.0
1.6
4.4
0.8
0.3
0.4
2.1
1.7
0.03
0.2
0.4
<0.1
A
• 0.5
2.2
2.0
0.2
1.8
0.1
0.1
0.2
0.3
0.4
0.0
0.1
0.1
0.02
Total
38.9
94.2
146.4
56.9
111.8
27.6
21.6
13.3
32.1
32.4
6.4
9.2
14.8
5.4
Concentrations in Ambient Air
5-5
-------
Table 5-4. ANNUAL AVERAGE AMBIENT BENZO [a] PYRENE CONCENTRATIONS
AT NASN URBAN STATIONS4'5
(ng/m3)
Station
Alabama
Birmingham
Gadsden
Huntsville
Mobile
Montgomery
Alaska
Anchorage
Arizona
Phoenix
Tucson
Arkansas
Little Rock
West Memphis
California
Burbank
Glendale
Long Beach
Los Angeles
Oakland
Ontario
Pasadena
Riverside
Sacramento
San Bernardino
San Diego
San Francisco
Colorado
Denver
Connecticut
Hartford
New Haven
Delaware
Newark
Wilmington
District of
Columbia
Florida
Jacksonville
Tampa
1966
18.5
3.5
6.5
2.3
1.7
0.6
1.2
1.1
2.5
2.1
2.7
1.8
1.7
1.1
2.3
2.3
3.5
1.0
2.2
2.4
1967
3.1
2.3
1.9
2.5
0.7
0.9
2.2
1.0
2.1
1.3
1.7
1.6
1.5
2.4
2.1
1.9
1.4
2.7
1.9
1968
2.4
2.7
4.2
2.9
1.7
2.1
0.7
0.9
2.2
1.6
2.1
1.8
1.6
0.9
2.3
1.3
1.4
1.0
1.2
1.8
2.3
1.4
1.4
0.9
1.9
1.9
2.9
1.5
1969
1.8
1.8
2.6
2.0
1.3
2.2
0.5
1.1
2.4
2.9
1.6
2.3
1.9
1.6
0.6
0.8
1.8
0.9
1.4
1.2
2.5
2.0
2.1
1.7
4.3
2.3
1.0
1970
2.5
1.6
1.3
0.8
0.4
0.7
0.6
1.9
1.0
1.0
1.2
1.0
0.6
0.7
0.7
0.7
0.8
0.7
0.6
2.2
1.4
1.2
0.4
1.1
1.4
0.5
5-6
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
Table 5-4 (continued). ANNUAL AVERAGE AMBIENT BENZO [a] PYRENE
CONCENTRATIONS AT NASN URBAN STATIONS4'5
(ng/nr1)
Station
Georgia
Atlanta
Hawaii
Honolulu
Idaho
Boise City
Illinois
Chicago
Springfield
Indiana
East Chicago
Hammond
Indianapolis
Muncie
New Albany
South Bend
Terre Haute
Iowa
Davenport
Des Moines
Cedar Rapids
Kansas
Kansas City
Topeka
Wichita
Kentucky
Ashland
Covington
Lexington
Louisville
Louisiana
New Orleans
Maine
Portland
Maryland
Baltimore
1966
1.4
0.2
3.5
3.3
6.8
3.9
10.4
Z4
5.4
2.2
3.2
2.5
1.2
0.8
10.5
3.1
2.5
Z3
2.8
1967
3.0
0.5
2.4
3.0
5.7
2.5
5.7
1.6
2.6
3.7
2.7
0.8
0.5
0.5
1.9
1.8
2.1
1.8
3.8
1968
1.8
0.6
2.0
3.1
1.1
1.9
2.1
4.1
3.7
1.1
0.7
1.2
0.7
1.0
9.3
3.6
3.0
2.7
1.6
2.3
2.3
1969
1.9
0.6
6.0
3.9
1.3
6.8
3.3
5.2
4.3
3.7
4.0
1.7
0.9
1.1
0.4
0.7
10.9
4.1
1.9
1.5
2.8
1970
0.9
0.2
1.1
2.0
0.9
5.3
1.7
2.3
3.7
2.4
2.8
0.9
0.7
0.3
2.4
0.3
0.5
6.7
4.4
1.6
1.1
1.1
2.1
Concentrations in Ambient Air
5-7
-------
Table 5-4 (continued). ANNUAL AVERAGE AMBIENT BENZO [a] PYRENE
CONCENTRATIONS AT NASN URBAN STATIONS4'5
(ng/m3)
Station
Massachusetts
Worchester
Michigan
Detroit
Flint
Grand Rapids
Trenton
Minnesota
Duluth
Minneapolis
Moorhead
St. Paul
Missouri
Kansas City
St. Louis
Montana
Helena
Nebraska
Omaha
Nevada
Las Vegas
Reno
New Hampshire
Concord
New Jersey
Camden
Glassboro
Jersey City
Marlton
Newark
Patterson
Perth Amboy
Trenton
New Mexico
Albuquerque
New York
New York City
1966
4.7
2.2
1.6
0.7
1.8
2.7
1.3
0.6
3.0
0.7
4.2
1.2
2.1
2.1
2.2
2.0
4.1
1967
5.4
1.4
2.8
1.3
2.3
2.3
0.8
1.3
1.1
4.6
1.5
0.8
3.5
1.6
3.3
1.9
2.1
1.9
3.9
1968
1.7
5.1
0.8
3.4
1.4
2.7
1.1
0.9
1.8
1.8
0.9
1.9
1.4
3.1
1.0
1.6
1.2
2.3
1.3
2.1
2.0
1.2
1.0
1.8
1969
1.5
3.9
1.7
1.7
1.6
2.1
1.4
1.0
1.8
1.6
3.3
0.5
1.6
0.7
2.4
1.1
2.7
1.8
1.2
1.2
1.5
1.1
3.6
1970
1.6
2.6
1.5
0.9
0.8
1.1
0.6
1.6
1.0
1.1
1.0
0.6
1.9
1.2
4.7
1.4
1.5
1.2
1.0
1.1
1.1
3.0
5-8
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
Table 5-4 (continued). ANNUAL AVERAGE AMBIENT BENZO [a] PYRENE
CONCENTRATIONS AT NASN URBAN STATIONS4'5
(ng/m3)
Station
North Carolina
Charlotte
Durham
North Dakota
Bismarck
Ohio
Akron
Cincinnati
Cleveland
Columbus
Dayton
Toledo
Youngstown
Oklahoma
Oklahoma City
Tulsa
Oregon
Eugene
Medford
Portland
Pennsylvania
Allentown
Altoona
Bethlehem
Harrisburg
Lancaster
Philadelphia
Pittsburgh
Reading
Scranton
Warminster
West Chester
Wilkes Barre
York
Rhode Island
East Providence
Providence
South Carolina
Columbia
Greenville
1966
5.7
4.1
3.6
3.1
2.9
2.7
1.8
7.3
1.5
0.7
3.3
2.3
3.8
4.9
2.3
0.9
3.6
5.0
1967
6.3
3.7
1.9
2.9
1.7
3.7
1.9
8.2
0.7
0.6
2.4
4.8
3.5
1.8
29.5
2.9
5.9
7.0
2.9
5.2
2.2
1.1
1.8
1.6
2.8
4.2
1968
5.6
8.0
0.9
3.0
1.8
3.0
2.2
2.4
1.8
5.6
0.7
0.8
8.2
4.1
1.2
18.0
2.1
1.3
2.9
6.3
2.4
6.1
0.9
1.0
1.6
1.9
1.2
2.0
6.2
18.6
1969
4.9
3.4
1.0
2.9
3.8
2.7
1.9
1.5
9.9
0.7
0.5
4.1
2.6
1.9
22.3
2.0
1.5
4.0
13.8
1.8
7.7
1.0
1.3
1.5
2.0
1.2
2.2
1.3
7.0
1970
1.9
3.9
0.4
2.6
2.8
1.6
1.5
1.4
7.1
0.9
0.8
2.3
2.4
19.3
2.7
1.5
2.4
5.9
1.6
2.9
1.3
1.2
1.2
2.1
3.4
Concentrations in Ambient Air
5-9
-------
Table 5-4 (continued). ANNUAL AVERAGE AMBIENT BENZO [a] PYRENE
CONCENTRATIONS AT NASN URBAN STATIONS4'5
(ng/m3)
Station
Tennessee
Chattanooga
Knoxville
Memphis
Nashville
Texas
Dallas
Houston
San Antonio
Utah
Ogden
Salt Lake City
Vermont
Burlington
Virginia
Danville
Hampton
Lynchburg
Norfolk
Portsmouth
Richmond
Roanoke
Washington
Seattle
West Virginia
Charleston
Wisconsin
Kenosha
Madison
Milwaukee
Superior
Wyoming
Casper
Cheyenne
1966
8.4
1.7
5.5
1.4
0.9
0.6
0.5
1.2
0.8
3.2
2.8
2.7
3.4
4.1
0.5
1967
22.9
7.0
1.6
7.0
1.4
0.7
2.2
9.2
3.5
7.7
5.2
7.5
1.8
1968
7.4
9.8
1.3
6.0
0.9
0.8
1.0
0.7
2.5
1.5
8.7
4.9
10.2
7.7
2.0
4.6
1.4
1.3
4.7
3.3
0.9
0.6
1969
4.2
4.7
0.7
2.8
2.0
0.6
0.7
0.7
0.5
1.8
0.9
6.3
3.9
3.4
2.2
5.3
1.6
2.6
1.7
4.0
1.6
0.6
0.5
1970
5.5
1.4
3.6
1.9
1.2
1.0
2.5
1.4
0.7
2.7
1.1
4.5
1.8
4.9
2.1
6.2
1.5
2.1
1.3
1.1
2.5
1.5
0.4
0.4
5-10
PARTICIPATE POLYCYCLIC ORGANIC MATTER
-------
Table 5-5. ANNUAL AVERAGE AMBIENT BENZO [a] PYRENE
CONCENTRATIONS AT NASN NONURBAN STATIONS4'5
(ng/m3)
Station
Arizona
Grand Canyon
Maricopa County
Arkansas
Montgomery County
California
Humboldt County
Idaho
Butte County
Indiana
Monroe County
Parks County
Maine
Acadia Natl Park
Missouri
Shannon County
Montana
Glacier Natl Park
Nebraska
Thomas County
Nevada
White Pine County
New Hampshire
Coos County
New York
Jefferson County
North Carolina
Cape Hatteras
Oklahoma
Cherokee County
Oregon
Curry County
Pennsylvania
Clarion County
1966
0.3
0.3
0.4
0.5
0.9
0.2
0.2
0.1
0.2
0.2
0.2
0.2
0.1
1.5
1967
0.2
0.2
0.1
0.4
0.2
0.3
0.2
0.2
1.1
2.1
1968
0.2
0.5
0.2
0.3
0.2
0.5
0.4
0.3
0.2
0.4
0.2
0.1
0.2
0.2
0.2
0.2
0.1
1.0
1969
0.2
0.3
0.2
0.5
0.1
0.3
0.3
0.1
0.2
0.4
0.1
0.1
0.1
0.3
0.1
0.2
0.1
1.2
1970
0.1
0.3
0.1
0.1
0.1
0.2
0.4
0.2
0.2
0.1
0.1
0.1
0.2
0.2
0.2
0.1
1.2
Concentrations in Ambient Air
5-11
-------
Table 5-5 (continued). ANNUAL AVERAGE AMBIENT BENZO [a] PYRENE
CONCENTRATIONS AT NASIM NONURBAN STATIONS4 -5
(ng/m3)
Station
Texas
Matagorda County
Vermont
Orange County
Virginia
Shenandoah Natl Park
1966
0.3
0.9
0.9
1967
0.1
0.3
1968
0.2
0.3
0.3
1969
0.1
0.3
0.3
1970
0.3
0.2
0.2
With only an occasional exception, the annual averages for the urban sites were remarkably consistent from
year to year for the period covered. Study of the data uncovers a number of facts: ambient levels are not
necessarily related to city size; cities like Los Angeles with high BSO levels generally attributed to auto
exhaust emissions and subsequent photochemical reactions do not necessarily have high ambient
concentrations of BaP; high concentrations are usually associated with heavily industrialized coal-burning
cities (Birmingham, Ashland, Pittsburgh); highest concentrations are exhibited in Altoona, which relies on
coal for heating purposes, and because of meteorological and geographical factors, is subject to frequent
fumigations from this source during the winter months. Many urban areas enjoy low ambient levels because
of the lack of contributing sources.
Concentrations at the nonurban stations were quite low, with the more remote stations (Idaho, Nevada,
Oregon) approaching minimum detectable levels. The higher levels occurring at the Clarion County,
Pennsylvania, station were no doubt due partly to its location downwind from the
Pittsburgh-Youngstown-Akron-Cleveland industrial complex. Domestic heating systems in the area may also
contribute, although these sources were probably minor as this station exhibits no pronounced seasonal
pattern, as Figure 5-1 shows.
Seasonal variations at three urban and two nonurban NASN sites over a 2-year period are graphically shown
in Figure 5-1. The graph not only shows the difference between sites but dramatically demonstrates the
influence of community parameters on the seasonal pattern as well.
The ratios of BaP concentrations to total suspended particulate (TSP) and BSO concentrations have been
computed for each of 3 years for approximately 100 urban and 19 nonurban NASN stations. These ratios
are shown in Table 5-6 and 5-7. To provide whole numbers for easier comparisons, the BaP/TSP ratio has
been multiplied by 100,000 and the BaP/BSO ratio by 10,000. Although many differences can be
detected by comparison of Tables 5-4 and 5-5 to 5-6 and 5-7, there are certain similarities. For Altoona and
Ashland, which have high BaP concentrations, both ratios for each city were high also. Pittsburgh and
Youngslown, with fairly high BaP levels, showed high BaP/BSO ratios, indicating the high BaP content of
the BSO fraction. Tucson, with low BaP levels, showed low ratios. Los Angeles had unusually low BaP/BSO
ratios because of the low levels of BaP and the high concentrations of BSO characteristic of that city. Most
of the nonurban stations appeared to follow the same general pattern, with Clarion County, Pennsylvania,
again having unusually high ratios in both cases.
5-12
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
40
30
20
10
9
8
7
6
5
et
CC
LU
O
O
O
cc
D-
O
M
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
\
\
\
\
— \
— \
CLARION COUNTY, PA. X
V
URBAN SITE
----- NONURBANSITE
CURRY COUNTY, ORE.
\
\
\
NOT DETECTABLE
\
2 3
1969
1
2 3
1970
TIME, quarter of year
Figure 5-1. Seasonal variations of benzo[a] pyrene at selected NASN stations.
Concentrations in Ambient Air
5-13
-------
5.4 BIRMINGHAM, ALABAMA, STUDY
During 1964 and 1965, Hauser and coworkers6 carried out a detailed study of POM from samples collected
at 10 different sites in Birmingham and suburbs. Seasonal composites comprised of 30 to 50 individual
samples were obtained for each of the 10 sites, extracted with benzene, and the benzene soluble fraction
was analyzed for 10 different PAH compounds. Annual average concentrations for each compound for each
site are shown in Table 5-8; the seasonal average of each hydrocarbon for the Greater Birmingham area is
given in Table 5-9; and interrelationships between the different polycyclics, the particulate sample, and the
benzene soluble fraction are shown in Table 5-10. Table 5-10 suggests that, in situations comparable to
those existing in Birmingham, measurement of any one of the polycyclic hydrocarbons would provide a
data base for use in computing concentrations of any of the others with some degree of accuracy. It must
be recognized, however, that extrapolation from one urban atmosphere to another is not possible because
of the variations in the emissions from different sources.
Table 5-6. RATIOS OF BENZO [a] PYRENE TO TOTAL SUSPENDED PARTICULATES
AND TO BENZENE-SOLUBLE ORGANICS AT NASN URBAN STATIONS4'5
Station
Alabama
Gadsden
Huntsville
Montgomery
Alaska
Anchorage
Arizona
Tucson
Arkansas
Little Rock
West Memphis
California
Glendale
Long Beach
Los Angeles
Oakland
Ontario
Riverside
Sacramento
San Bernardino
San Diego
San Francisco
Colorado
Denver
BaPATSP3
1968
2.6
4.3
3.6
2.2
0.9
1.2
2.5
1.6
1.6
1.4
1.8
0.7
1.0
2.0
0.9
1.8
2.0
ZO
1969
2.8
2.8
2.4
1.2
0.6
1.3
3.0
2.1
2.0
1.8
2.0
0.4
0.6
2.9
0.8
1.7
2.0
1.9
1970
3.1
2.4
1.4
0.9
0.4
0.9
0.7
1.1
1.0
0.9
1.4
0.4
0.4
0.5
1.0
0.6
1.2
1.7
BaP/BSOa
1968
2.9
4.7
2.8
3.1
1.9
1.6
3.7
1.3
1.6
1.2
2.4
1.2
1 4
2.0
1.5
2.1
1.6
2.9
1969
4.6
4.2
2.6
2.3
1.7
1.8
4.6
1.9
2.8
1 5
2.5
1.0
1 1
2 5
1.5
2 1
2.4
2.8
1970
6.4
4.0
2.1
1.8
1.2
1 7
1.7
1 4
1 9
1 4
2.3
0.9
1 0
1 9
0.9
1 8
2.0
2.7
5-14
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
Table 5-6 (continued). RATIOS OF BEIMZO [a] PYRENE TO TOTAL SUSPENDED PARTI-
CULATES AND TO BENZENE-SOLUBLE ORGANICS AT NASN URBAN STATIONS4'5
Station
Connecticut
Hartford
New Haven
Florida
Jacksonville
Tampa
Georgia
Atlanta
Hawaii
Honolulu
Idaho
Boise City
Illinois
Chicago
Springfield
Indiana
East Chicago
Hammond
Indianapolis
Iowa
Des Moines
Kansas
Topeka
Wichita
Kentucky
Ashland
Covington
Louisiana
New Orleans
Maryland
Baltimore
Massachusetts
Worchester
BaP/TSPa
1968
2.1
1.9
3.5
1.5
2.0
1.2
3.0
2.5
1.6
1.2
20
3.2
1.1
1.0
1.7
7.1
4.0
1.8
2.1
2.0
1969
2.8
22
2.8
1.3
22
1.4
5.7
2.7
1.6
3.6
2.6
4.4
0.9
0.7
1.0
6.0
4.1
2.0
2.3
1.5
1970
2.0
1.2
2.0
0.5
1.1
0.5
1.6
1.6
1.0
2.8
1.3
2.0
0.7
0.4
0.5
4.4
4.5
1.4
1.5
1.4
BaP/BSOa
1968
3.2
2.8
3.1
2.4
2.8
2.0
3.8
4.2
2.9
2.8
4.0
4.7
26
2.0
3.1
10.2
5.7
1.8
3.1
28
1969
4.5
3.8
3.4
2.4
2.9
2.5
7.6
5.3
3.1
9.6
5.3
6.2
2.1
1.3
1.9
10.6
6.2
2.2
3.8
2.5
1970
4.3
2.8
2.9
1.4
1.9
1.1
3.0
3.5
2.5
8.9
3.4
4.6
1.9
1.0
1.5
11.5
8.1
2.2
3.6
3.0
Concentrations in Ambient Air
5-15
-------
Table 5-6 (continued). RATIOS OF BENZO [a] PYRENE TO TOTAL SUSPENDED PARTI-
CULATES AND TO BENZENE-SOLUBLE ORGANICS AT NASN URBAN STATIONS4'5
Station
Michigan
Detroit
Flint
Grand Rapids
Trenton
Minnesota
Duluth
Minneapolis
Moorhead
St Paul
Nebraska
Omaha
New Hampshire
Concord
New Jersey
Camden
Glassboro
Jersey City
Newark
Patterson
Perth Amboy
Trenton
New Mexico
Albuquerque
North Carolina
Charlotte
Durham
North Dakota
Bismarck
Ohio
Cincinnati
Cleveland
Columbus
Dayton
Toledo
Youngstown
BaP/TSPa _J
1968
3.3
1.0
3.3
1.2
3.2
1.4
1.1
1.7
1.3
25
1.2
1.7
2.2
2.3
2.2
1.3
1.6
1.9
4.3
5.6
1.0
1.6
22
2.3
2.1
2.0
4.5
1969
3.0
1.9
1.7
1.6
2.6
1.9
1.5
2.4
1.4
1.9
1.9
1.6
3.0
2.5
1.6
1.5
1.9
1.4
4.5
4.0
1.2
25
2.9
2.6
1.9
2.0
7.5
1970
2.0
1.8
1.1
0.8
1.5
0.7
2.0
0.9
0.8
1.5
1.7
1.7
4.7
1.8
1.2
1.2
1.3
1.1
2.4
3.7
0.5
24
2.2
1.6
1.5
1.7
5.3
BaP/BSOa
1968
7.0
2.3
6.5
2.8
5.7
2.8
2.7
3.3
2.6
3.1
2.7
27
3.7
3.1
2.5
2.4
3.3
2.7
6.6
7.5
2.5
2.5
3.4
4.2
3.7
3.6
7.2
1969
6.6
4.6
4.1
3.8
4.8
24
2.9
3.4
2.9
2.3
3.4
27
4.3
3.1
2.4
27
2.8
2.4
7.0
5.2
2.4
3.3
6.3
5.4
4.0
3.7
16.2
1970
5.8
5.7
25
2.6
3.6
1.7
4.4
2.4
22
2.4
3.2
2.6
8.0
2.8
1.8
2.7
2.6
24
3.8
5.9
1.4
5.9
5.8
5.2
4.0
4.3
13.0
5-16
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
Table 5-6 (continued). RATIOS OF BENZO [a] PYRENE TO TOTAL SUSPENDED PARTI-
CULATES AND TO BENZENE-SOLUBLE ORGANICS AT NASN URBAN STATIONS4'5
Station
Oklahoma
Oklahoma City
Tulsa
Oregon
Portland
Pennsylvania
Allentown
Altoona
Bethlehem
Harris burg
Philadelphia
Pittsburgh
Reading
Scranton
Wilkes Barre
York
Rhode Island
East Providence
Providence
South Carolina
Greenville
Tennessee
Chattanooga
Memphis
Nashville
Texas
San Antonio
Utah
Ogden
Salt Lake City
Vermont
Burlington
Virginia
Danville
Hampton
Lynchburg
Norfolk
Portsmouth
Roanoke
BaP/TSPa
1968
1.4
1.4
5.2
1.3
19.5
2.1
2.0
2.3
3.5
1.8
2.5
1.3
1.7
1.8
2.1
16.0
4.8
1.7
5.1
1.4
1.3
1.3
1.6
2.5
2.3
7.1
4.9
8.3
8.3
1969
1.0
0.7
3.1
1.9
223
2.3
2.1
3.1
8.3
1.8
3.4
1.6
1.8
1.9
2.7
8.6
3.8
1.0
2.9
1.2
0.8
0.7
1.0
2.4
1.8
6.8
4.2
4.1
5.8
1970
1.2
1.3
2.2
20
8.8
2.5
1.7
1.7
4.3
1.3
1.5
1.3
1.2
2.1
2.3
3.8
4.4
1.6
3.6
1.6
2.5
1.6
1.1
2.8
1.8
3.6
2.0
5.0
6.3
BaP/BSOa
1968
2.1
2.4
6.7
2.7
15.9
4.8
2.9
3.4
6.9
3.4
3.3
2.6
3.0
2.3
2.8
12.8
6.8
2.9
6.4
1.9
2.3
2.6
2.8
3.3
3.6
8.2
8.8
12.1
9.0
1969
1.5
1.5
4.0
3.8
21.2
4.9
3.2
5.0
16.8
3.7
4.8
3.1
3.3
3.3
4.0
9.6
6.0
1.5
4.2
1.4
1.6
1.6
2.2
4.1
2.8
8.7
9.5
6.7
8.4
1970
2.8
2.6
3.1
4.2
11.2
6.4
3.3
2.9
9.8
3.1
2.4
2.9
2.8
3.4
4.6
4.1
6.7
3.4
5.6
3.0
3.6
3.4
2.9
5.3
3.7
5.9
4.9
9.9
9.4
i
Concentrations in Ambient Air
5-17
-------
Table 5-6 (continued). RATIOS OF BENZO [a] PYRENE TO TOTAL SUSPENDED PARTI-
CULATES AND TO BENZENE SOLUBLE ORGANICS AT NASN URBAN STATIONS4'5
Station
Washington
Seattle
West Virginia
Charleston
Wisconsin
Kenosha
Madison
Milwaukee
Superior
Wyoming
Casper
Cheyenne
BaP/TSPa
1968
2.9
1.5
2.0
1.8
2.8
3.9
1.5
1.9
1969
2.5
1.2
2.2
3.3
2.4
0.9
1.4
1970
2.2
1.2
1.8
1.4
2.3
1.9
0.7
1.2
1968
3.1
7.5
3.4
3.1
6.9
8.5
3.3
2.9
BaP/BSOa
1969
2.7
4.2
4.0
6.7
4.9
1.7
2.4
— i
1970
3.0
4.7
4.4
3.2
6.0
5.0
2.2
2.4
aTo provide whole numbers for easier comparison, the BaP/TSP ratio has been multiplied by 100,000 and the BaP/BSO
ratio by 10,000
Table 5-7. RATIOS OF BENZO [a] PYRENE TO TOTAL SUSPENDED PARTICULATES
AND TO BENZENE-SOLUBLE ORGANICS AT NASN NONURBAN STATIONS4'5
Station
Pennsylvania
Clarion County
Texas
Matagorda County
Vermont
Orange County
Virginia
Shenandoah Natl Park
BaP/TSP3
1968
2.6
0.6
1.0
1.0
1969
3.6
0.4
1.0
0.9
1970
2.6
0.9
0.5
0.6
BaP/BSO a
1968
3.6
1.1
1.5
1.7
1969
5.1
0.9
1.8
2.1
1970
7.2
2.7
1.5
1.9
°To provide whole numbers for easier comparisons, the BaP/TSP ratio has been multiplied by 100,000 and the BaP/BSO'
ratio by 10,000.
5-18
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
Table 5-8 provides a profile of the entire area with respect to each of the compounds. This example
demonstrates the effect of localized sources on the immediate surroundings. The differences between the
different neighborhoods were quite striking in many instances, but serve to illustrate source emission
variations over the area. The seasonal data in Table 5-9 are derived from a broad data base and consequently
were indicative of the types of sources contributing PPOM to Birmingham's air. The high degree of
correlation among the hydrocarbon compounds shown in Table 5-10 indicated a common source for most
of these pollutants and also showed that the level of one compound may be used as a fairly good index of
the concentrations of the others. Obviously this generalization holds only for a given metropolitan area over
a long period of time.
Table 5-a ANNUAL AVERAGE CONCENTRATION OF PAH COMPOUNDS IN THE
AIR OVER GREATER BIRMINGHAM, ALABAMA, 1964 and 19656
(ng/m3)
City
Bessemer
Birmingham
Fairfield
Irondale
Mt Brook
Tar rant
Vestavia
Site
1
3
4
5
7
1
1
1
1
1
Average
Fluor
7.0
4.9
11.2
10.8
2.6
10.0
3.4
1.0
3.4
1.0
5.5
P
7.6
4.6
10.8
9.1
2.5
8.1
2.8
1.0
3.6
1.0
5.1
BaA
7.8
5.3
21.2
14.5
3.4
13.3
4.2
1.0
3.9
1.0
7.6
Ch
13.1
8.1
27.9
14.2
4.4
11.3
5.7
2.2
7.6
2.0
9.6
BeP
10.5
7.6
26.1
15.0
5.6
13.3
6.3
3.0
7.6
2.9
9.8
BaP
13.5
9.0
35.8
20.5
6.0
18.2
7.6
2.6
7.4
2.4
12.3
Per
1.3
0.9
4.1
2.0
0.4
1.4
0.6
0.2
0.8
0.2
1.2
BghiP
14.1
9.5
22.4
15.3
7.9
11.8
7.0
3.7
8.2
3.5
10.3
A
1.2
0.7
2.2
1.2
0.3
1.1
0.4
0.1
0.2
0.1
0.8
Cor
2.6
2.7
3.8
3.5
2.7
2.1
1.9
1.4
2.2
1.2
2.4
Concentrations in Ambient Air
5-19
-------
Table 5-9. SEASONAL AVERAGE CONCENTRATIONS OF PAH COMPOUNDS
IN THE AIR OVER GREATER BIRMINGHAM, ALABAMA, 1964 and 1965s
(ng/m3)
Compound
Fluor
P
BaA
Ch
BeP
BaP
Per
BghiP
A
Cor
Spring
4.4
3.7
6.8
8.8
10.0
13.7
1.3
9.6
0.9
2.1
Summer
1.8
1.6
2.9
4.9
7.5
6.8
0.8
7.4
0.3
1.9
Fall
3.4
3.1
7.5
10.8
10.1
11.6
1.2
11.4
0.6
3.1
Winter
12.5
12.1
13.1
14.1
11.6
17.1
1.5
12.8
1.2
2.6
5-20
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
Table 5-10. INTERRELATIONSHIPS BETWEEN PAH COMPOUNDS IN THE AIR OVER
GREATER BIRMINGHAM, ALABAMA, 1964 and 19656
n
o
3
rt-
l-t
o
3
n
er
Compound
Fluor
P
BaA
Ch
BeP
BaP
Per
BghiP
A
Cor
TSP
BSO
Fluor
1.000
0.984a
0.959a
0.866
0.9023
0.916a
0.848
0.909a
0.91 3a
0.779
0.668
0.582
P
1.000
0.956a
0.91 9a
0.9273
0.935a
0.887a
0.9573
0.952a
0.816
0.730
0.684
BaA
1.000
0.944a
0.9803
0.9883
0.951a
0.9463
0.9553
0.802
0.742
0.597
Ch
1.000
0.9863
0.9803
0.9893
0.9813
0.9713
0.830
0.842
0.746
BeP
1.000
0.9983
0.9903
0.9683
0.96 33
0.823
0.823
0.677
BaP
1.000
0.9853
0.9663
0.9713
0.815
0.789
0.651
Per
1.000
0.9563
0.9533
0.817
0.830
0.689
BghiP
1.000
0.9743
0.895a
0.839
0.804
A
1.000
0.807
0.716
0.672
Cor
1.000
0.856
0.867
TSP
1.000
0.880
BSO
1.000
Denotes significance at p = 0.001 (r > 0.872). Dixon, W. J., and F. J. Massey, Jr. Introduction to Statistical Analysis (3rd edj.New
York, McGraw Hill, 1969. Table A-30a, p. 549.
-------
5.5 AZA HETEROCYCLIC ORGANIC COMPOUNDS
The aza heterocyclic organic compounds, which are characterized by the presence of nitrogen in place of
carbon in one or more of the aromatic rings, have been neglected until fairly recently. This was in part due
to the fact that these materials are found in the basic fraction, which constitutes a small portion of
benzene-soluble orgarucs. For many years, the emphasis centered on the aromatic hydrocarbon fraction.
The recognition by Sawicki and others that potential carcinogens could be found in the basic fraction led to
gatheringV considerable data on levels of these compounds in the atmosphere.7
The approximate concentrations of six aza heterocyclics in the benzene soluble organic fraction from six
large cities are given in Table 5-11. The values are only semiquantitative because at the time the work was
performed the methodology had not been fully perfected. In addition to these six compounds, 13 other aza
heterocyclics were qualitatively detected in the Nashville sample.
5.6 SIZE DISTRIBUTION OF BaP-CONTAINING PARTICULATE MATTER
In evaluating potential effects of PPOM, it is essential to have data relative to the particle size distribution.
As of this time, very little information is available. In a study of particulates in Pittsburgh, Pa., DeMario and
Corn concluded that more than 75 percent of the BaP and several other hydrocarbons was associated with
aerosols less than 2.5 /jm in radius.8 More recently Kertes-Saringer and co-workers reported that in
Bucharest from 70 to 90 percent of the total BaP was associated with aerosols with a radius of 1 ^m or
less.9
Table 5-11. APPROXIMATE CONCENTRATIONS OF AZA HETEROCYCLIC COMPOUNDS
IN BENZENE-SOLUBLE FRACTION OF SELECTED URBAN ATMOSPHERES6
Compound
Benzo[f] quinoline
Benzo[h] quinoline
Benz[a] acridine
Benz[c] acridine
11H-lndeno[1,2-b]
quinoline
Dibenz[a,j] acridine
Urban Area
»
Atlanta
200
20
200
30
30
8
Cincinnati
80
20
80
10
40
2
Los
Angeles
a
1
3
1
4
a
Nashville
100
30
70
8
20
6
New
Orleans
7
1
20
2
8
0.6
Philadelphia
20
7
30
6
10
6
Unable to detect in the amount of sample analyzed.
5-22 PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
5.7 SUMMARY
Man is surrounded by an air environment that contains a large assortment of complex organic compounds.
Many fit into the category of what is commonly called particulate polycyclics. Although the greatest
emphasis in the past has been placed on the polycyclic hydrocarbons- especially BaP - it must be
recognized that there are other constitutent groups such as the aza heterocyclics that, although found in
smaller amounts, may be of considerable significance because of their biological activity.
Five years of BaP data collected by NASN indicate definite source/concentration relationships, with highest
levels occurring in those urban areas that use large amounts of coal or fuel oil both in their normal domestic
activities and in industrial processes. Annual average urban concentrations range from 0.48 ng/m3 for
Honolulu and 0.73 ng/m3 for Tucson to a maximum of 22.2 ng/m3 for Altoona. This represents a 1 to 50
range among urban areas. At the more remote locations, the levels are usually much lower, with a minimum
annual average of 0.10 ng/m3 for Curry County, Oregon, and a maximum of 1.7 for Clarion County,
Pennsylvania. The latter is an excellent example of the intrusion of urban pollutants into an otherwise
unpolluted environment.
There is some question as to whether, because of year to year variability, the 1966 to 1970 data are an
adequate base to determine trends. These fluctuations in annual averages could be the result of low
frequency of sampling and poor precision in analysis, climate variation, as well as day to day variation in
emissions. Consequently, any trend analysis would be of doubtful significance.
Typical seasonal fluctuations are shown quite clearly in Tables 5-2 and 5-9 and Figure 5-1. The Altoona
data illustrate the influence of emissions from inefficient coal-burning installations.
Measurable amounts of several aza heterocyclics have been found in a number of urban atmospheres.
Relatively little effort has been expanded on investigation of the particle size distribution of PPOM. The
small amount of data available indicates that 75 percent more of BaP is associated with particles with less
than 2.5 ,um radius, which would tend to emphasize the respirability of PPOM. This is an extremely
important point to consider when investigating the biological effects of PPOM.
5.8 REFERENCES
1. Sawicki, E., T. R. Mauser, W. C. Elbert, F. T. Fox, and J. E. Meeker. Polynuclear Aromatic
Hydrocarbon Composition of the Atmosphere in Some Large American Cities. Amer. Ind. Hyg. Ass. J.
23:131-144, 1962.
2. Hartwell, J. L, and P. Shubik. Survey of Compounds Which Have Been Tested for Carcinogenic Activity.
In five volumes: Through 1947, 1948-1953, 1954-1960, 1961-1967, 1968-1969. Public Health Service,
Washington, D. C. Publication Number 149.
3. Sawicki, E., W. C. Elbert, T. R, Hauser, F. T. Fox, and T. W. Stanley. Benzo[a] pyrene Content of the
Air of American Communities. Amer. Ind. Hyg. Ass. J. 27:443-451, 1960.
4. Air Quality Data for 1966. U. S. Environmental Protection Agency, Research Triangle Park, N. C. APTD
68-9, 1968.
5. NASN Ambient BaP Data, National Aerometric Data Bank. U. S. Environmental Protection Agency,
Research Triangle Park, N. C.
6. Hauser, T. R., J. J. Henderson, and F. B. Benson. The Polynuclear Hydrocarbon and Metal Concentra-
tion of the Air Over the Greater Birmingham Area. Unpublished Report. U. S. Environmental Protection
Agency, National Environmental Research Center, Research Triangle Park, N. C.
Concentrations in Ambient Air 5-23
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7. Sawicki, E., S. P. McPherson, T. W. Stanley, J. Meeker, and W. C. Elbert. Int. J. Air Water Pollut.
9:515-524, 1965.
8. DeMaio, L, and M. Corn. Polynuclear Aromatic Hydrocarbons Associated with Particulates in Pittsburgh
Air. J. Air Pollut. Contr. Ass. 16:67-71, 1966.
9. Kertesz-Saringer, M., E. Meszaros, and T. Varkonyi. On the Size Distribution of Benzo[a]pyrene
Containing Particles in Urban Air. Atmos. Environ. 5:429-431, 1971.
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6. EFFECTS ON HUMAN HEALTH
6.1 TO XICO LOGICAL APPRAISAL
6.1.1 Introduction
The association between development of cancer and excessive contact with an environmental contaminant
was first made in 1776 when the British physician Percival Pott noted the high incidence of cancer of the
scrotum in the chimney sweeps of London. He correctly attributed the disease to their continual contact
with soot.1 The earliest laboratory investigation based on this observation was by the Japanese investigators
Yamagiwa and Ichikawa in 1915.2 They painted coal tar on the skin of mice and found that tumors
developed after several months of repeated local applications. The first inquiry into the chemical basis of
"tar cancer" was that of Bloch and Drcifuss.3 Subsequent studies by Kennaway in 1925 identified the
tumorogenic material as a hydrocarbon.4 Chemical isolation of benzopyrenc, dibenz(a,i)-anthracene,
7,12-dimethylbenz[a] anthracene, and 3-methylcholanthrene was accomplished by Cook, Hewett, and
Keger in 1933.s Subsequent studies by Kennaway showed these substances to be actively carcinogenic to
animals.6 These early studies focused attention on the carcinogenicity of polycyclic aromatic hydrocarbons
and guided subsequent toxicology laboratory research in that direction.
Animal toxicologic studies have been done on many compounds that have been identified in the PPOM of
ambient air. The systemic acute LD50 (the lethal dose for 50 percent of animals tested) is usually so much
higher than doses shown to be carcinogenic in single or multiple doses that such data are rarely
mentioned.7'5 Recent in vitro toxicity studies have shown some PPOM compounds to be toxic to some
human cell types but do not result in malignancy.9 Studies designed to evaluate noncarcinogenic effects of
PPOM are rare, and studies that are designed as carcinogenesis experiments and that yield negative results
usually fail to use data on noncarcinogenic effects. Little or no work has been done on the possible
teratogenic or mutagenic effects of PPOM. Therefore, any appraisal of the toxicology of PPOM will be
almost entirely a discussion of carcinogenicity.
Research on the toxicology of PPOM can be grouped under four broad headings:
• Determination of carcinogenicity a
• Determination of biologic handling in vivo and in vitro
• Determination of a dose-response pattern in experimental animals that can be applied to setting an air
quality standard
• Determination of teratogenesis and mutagenesis
6.1.2 Determination of Carcinogenicity
Many screening methods have been devised to evaluate carcinogenicity. They have utilized pure samples of
organic compounds of the types found in the environment, as well as total PPOM and fractions collected
from urban atmospheres.
Carcinogenic potential of extracts of airborne material has been undertaken on various whole animals,
tissue cultures, organ cultures, and microorganisms. The methods employed on whole animals have been
skin painting, subcutaneous injection, systemic inoculation, oral intake, local implantation (in lung,
bladder, or other organs), intratracheal inoculation, and inhalation.
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6.1.2.1 Animal Cutaneous Bioassay-Much of the early work in experimental carcinogenesis was
accomplished by repeated painting of materials on the intact skin of mice. The carcinogenicity of chimney
soot,10 road dust,11 city airborne dust,12~18 and smoke13 was determined by skin painting. This method
was'also used in studies that suggested that the PAH fraction of urban air particulates may play an
important role in carcinogenicity.14'15'17'19'20 A large series of experiments carried out with various
extracts and fractions of airborne particulates from various sources in the United States indicated that there
were geographic differences in biological activity, with the highest incidence of tumors associated with
material from Birmingham and the lowest incidence with that from Los Angeles.15 Analysis of these data
indicates that tumorogenicity could not be entirely related to the BaP content of these extracts^ Another
study showed mat oxidation products of aliphatic hydrocarbons were also carcinogenic.^ Some
N-heterocyclic hydrocarbons identified in urban air have also been shown to be carcinogens.22 M The
technique of applying carcinogens to mouse skin has been refined so that effects can be seen in female
Ha/ICR/mil (Swiss random bred albino) mice with as little as 50 microliters (jul) of a 0.001 to 0.002 percent
acetone solution of BaP.25
6.1.2.2 Animal Subcutaneous Bioassay—Subcutaneous injection of suspected chemical carcinogens or
organic pollutants into mice, 26'27 rats ,28 and hamsters, 29>3° has been shown to be an effective bioassay
method. The inbred hamster line developed tumors after one 0.5 milligram (mg) injection of
7,12-dimethylbenz[a] anthracene with amean latency of 9 weeks.
6.1.2.3 Animal Oral Intake—Carcinogenesis has been reported following oral administration of PAH or
aromatic amines in oil to Sprague-Dawley rats.31'32 Oral administration, however, is felt to be a relatively
poor way of determining the carcinogenicity of PPOM, except possibly in the case of tumors of the
gastrointestinal tract.28
6.1.2.4 Animal Pellet Implantation Bioassay—Local implantation of pellets impregnated with carcinogen
lias been used in the lung33'34 and in the bladder.35"39 This is a technique for applying pure carcinogens
directly to the target tissue. It is not likely that local implantation will gain widespread use as a screening
method.28
6.1.2.5 Animal Neonate Injection Bioassay—The subcutaneous and systemic inoculation of newborn
animals has been shown to be a sensitive bioassay method for carcinogenicity.40"44 Cancer can be
produced in these animals with a higher incidence than it can using comparable doses in adult animals.40 A
single subcutaneous injection of 0.06 mg of dibenz[a,h] anthracene and 0.1 mg of 3-methylcholanthrene
into 1-day-old mice produced a high incidence of malignant tumors in 8 to 32 weeks.41 This method has
also been used to assay fractions of air particulates.43'44 Results were similar to the previously mentioned
study that used cutaneous and subcutaneous inoculation of adult animals, but with the advantage that
neonatal studies use much smaller amounts of material and shorter latent periods.15
6.1.2.6 Animal Intratracheal Inoculation Biossay-Although PPOM does come into contact with the skin,
the primary concern is its action when taken into the lung. The development of intratracheal inoculation
techniques allowed investigators to deposit high concentrations of potentially carcinogenic materials into
the lung by a simple, inexpensive technique. Many initial experiments with this technique did not result in
formation of malignant tumors in the lung.45"47 In 1949, Niskanen used repeated intratracheal injections of
a suspension of dibenz[a,h] anthracene in olive oil and induced squamous cell carcinomas in six of 25
rats.48 The intratracheal method was further refined by Delia Porta, Kolb, and Shubik who injected a
colloidal gelatin suspension of 7,12-dimethylbenz[a] anthracene into Syrian golden hamsters by repeated
endotracheal instillations.49 Squamous cell carcinomas of the larynx and trachea were seen in six of 17
hamsters. An appreciable incidence of lung tumors was produced by the intratracheal administration of
7,12-dimethylbenz[a] anthracene suspended in a balanced saline solution containing 4 percent casein and
India ink powder.50 In further investigations, other agents including BaP and purified carbon particles
instead of India ink were used.51"56 This method was very successful in producing malignancies of the
lung; a 67 percent incidence of squamous cell carcinoma was produced by BaP.
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The incorporation of BaP with hematite particles (Fe203) lias also been extremely productive of tumors
when equal parts arc physically ground together, suspended in saline, and injected via the trachea of Syrian
hamsters.57"64
Experimentation with the carcinogen-hematite-Syrian hamster model has been extremely successful in
inducing a large number of cancers of the trachcobronchial tree and lung parenchyma that mimic those
occurring naturally in human beings.63 The hamster is uniquely free of inflammation and spontaneous
tumors of the lung.65 In these experiments with BaP and hematite, cancer incidences as high as 100 percent
have been reported. The success of the intratracheal injection method appears to be related to addition of
some other physical factors. No tumors resulted from injection of BaP alone,33'47 whereas addition of a
cofactor such as carbon particles50"56 or hematite57"64 produced a striking effect.
In developing a model for intratracheal injection, pure compounds of known or suspected hydrocarbon
carcinogens from the air were used. This model has been applied in preliminary studies of crude air
particulates, organic fractions of air particulates, and combinations of these with equal amounts of BaP or
hematite.66 This model is also being widely used to screen other pure, suspected carcinogens. Sellakumar
and Shubik report an 89 percent incidence of respiratory tract tumors in hamsters given a total dose of 15
mg of 7H-dibenzo[c,g]-carbazole and hematite.67 Experiments that employ repeated intratracheal
injections must be accepted with caution.68 All such experiments are complicated by damage to the
ciliated mucosa, plugging of the finer airways, introduction of infectious agents, irritation from the
chemical and its carrier or solvent, and effects of repeated anesthesia (if used). In the case of rats
maintained for long periods, the usual rat lung pathology interferes with interpretation of the
experiment.68
6.1.2.7 Animal Inhalation Bioassay—Exposure of animals by inhalation techniques offers the most
physiologic approach to experimental carcinogenesis in the lung. Experiments of this type are most relevant
to the problem of air pollution and are cogent criteria for setting air quality standards.6 9"71 Some studies
using inhalation of pure polycyclic hydrocarbons, however, have yielded negative results.47 Only scattered
success has been reported in producing lung tumors with inhalation techniques. The incidence of
pulmonary adenomata in mice was reported to be increased by exposure to dust from tarred roads,' 2>72-73
chimney soot,74'75 and fractions of coal tars.76 A model consisting of exposure of mice to a mixture of
ozone and gasoline vapor has been employed with some success.77'78 Incorporation of exposure to
influenza virus in this model increased the number of tumors.79'80 A subsequent series of experiments by
other investigators employing this model produced increased evidence of pulmonary carcinomas and
adenomas in C.57 strain black mice by exposure to ozonized gasoline fumes. In these experiments,
however, inhibition of tumor growth resulted from influenza infection.81
A relative inhalation study was carried out using a combination of sulfur dioxide and particulate BaP.33
For these experiments, rates were exposed to 26.2 milligrams per cubic meter (mg/m3)S02 for 6 hours a
day, 5 days a week. For 1 hour a day, 10 mg/m3 BaP and 9.2 mg/m3 S02 were added to the atmosphere.
Exposure was for 98 weeks, and appropriate controls were used. Five of 21 rats developed lung tumors. The
BaP-hematite-Syrian hamster model has not been studied by inhalation. Recently, Clark and Schmoyer
developed methods to generate aerosols of respirable particles that have polycyclic organic carcinogens
associated with noncarcinogenic carriers, such as hematite and carbon.82 It is hoped that these
developments will lead to bioassay systems yielding data directly applicable as air quality criteria.
(Epidemiological data question the noncarcinogenicity of hematite. See: Boyd, J.T. and R. Doll. Cancer of
the Lung in Iron-Ore (Haematite) Miners. Brit. J. Prev. Med. p. 63, 1970.)
6.1.2.8 In Vitro PPOM Bioassay-ln 1963, Berwald and Sachs described characteristic morphologic
alterations in the growth patterns of hamsters and embryonic fibroblasts in culture with PAH.83 They later
demonstrated that these cells gave rise to tumors when the cells were transplanted to hamster cheek
pouches.84 A proportionality was shown between the number of transformed clones produced by a given
hydrocarbon and its known carcinogenic activity.85"87 Several investigators attempted to use cultures of
mouse ventral prostate for bioassay.88"92 These studies led to the development of a quantitative system
Effects on Human Health 6-3
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with prostate cells in which morphologically transformed colonies were easily identified in culture; all of
these colonies resulted in tumors upon transplantation to mice.93 The number of transformed colonies
correlated with known carcinogenic activity when nine polycyclic hydrocarbons were studied.
Huebner et al. also developed an in vitro screening technique for large numbers of possible
carcinogens.94'95 These studies employ rodent embryonic fibroblast cell lines that are not transformed by
either known carcinogens or nontransforming type-C RNA tumor virus individually. However, when these
cultures are infected with virus and then exposed to a carcinogen, transformation takes place.
Organ culture has also been used for bioassay. Respiratory96'97 and prostatic89'98 tissues undergo
morphologic changes in proportion to the established in iwo-animal activity of many known carcinogens.
Using suckling rat tracheas, Crocker and his associates established the similarity between early in vivo and in
vitro morphologic changes in this system with air particulate extracts and pure known carcino-
gens.96'99"101 In vitro methods for screening effects of PPOM have the advantage that dose-response
analysis of relative biologic activity can be easily accomplished, concentration and duration of exposure can
be better controlled, and human tissues can be exposed directly to compounds that could not be used
safely in vivo in human studies. One investigator102 has reported epithelial hype rplasia of human epithelial
tissue in vitro as a result of BaP activity, and one group9 has reported toxic effects at 1 jug per milliliter
levels of hydrocarbon in culture. The use of human cells in vitro should be further explored as a test system
for screening and determining relative carcinogenicity of PPOM.
6.1.2.9 Indirect Tests Used for PPOM Bioassay-The suppression of sebaceous glands of mouse
skin103"108 and the photodynamic assay of Paramedum caudatum109'11* have been found to correlate
with carcinogenicity of some substances. None of these tests have had goals of carcinogenicity, but because
they have shown a correlation in cases of known carcinogens, they may have some value as screening tests.
6.1.2.10 Testing for Carcinogenicity in Primates— Experimental carcinogenesis caused by PAH has been
achieved in prosimian primates.1! 5-11 9 Administering methylcholanthrene, dibenzanthracene, and BaP by
many routes, Pfeiffer and Allen failed to produce cancer in simians.120 This raised questions of resistance
due to metabolic or immune characteristics that may also be present in man. Primates of the suborder
Prosimii appear more susceptible to carcinogenesis by PAH.119 Pulmonary carcinoma in simians has been
produced by administration of particles of beryllium salt,1 21 and hepatic carcinoma has been produced by
oral administration of nitrosamines.122 Domestically bred simian primates should be tested with methods
identical to those which succeeded in prosimian primates and rodents in order to provide data on the
relative susceptibility to systemic, skin, and bronchial carcinogenesis by PAH in the primate suborder that
includes man.28
6.1.2.11 Discussion-Extensive research has been done on methods to be used in bioassay of carcinogens.
Most of these methods have used the same known carcinogens to ensure that the assay is accurate.
Similarly, methods have been applied to assay of chemical fractions of air particulates. In no case have all
the compounds in these fractions been characterized Nevertheless, these studies have identified many
carcinogens in the air as noted in Table 5-1 but others remain to be evaluated.
None of the toxicological data presented thus far can be extrapolated for the determination of an air
quality standard unless that standard attempts to completely eliminate all carcinogens from the
atmosphere.
6.1.3 Determination of Biologic Handling In Vivo and In Vitro
Much information has been gained on the interaction of PPOM and animal systems. Information is available
on: deposition of PPOM in the lung, the role of other factors in potentiating PPOM activity, clearance of
PPOM from the lung, metabolism and distribution of PPOM, enzyme systems that change these carcinogens
in vivo, chemical carcinogenesis at the molecular level in the cell, modification of PPOM interaction by
modification of host factors, and diagnosis of results of PPOM jnhalation. Although many of these factors
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do not appear to be directly involved in the task of establishing air quality criteria for PPOM, their
discussion is included here because all play an important role in understanding the biologic effects of these
compounds.
6.1.3.1 Deposition, Potentiation, and Clearance—Airborne particles range from 0.001 to 10,000 jum in
diameter, with the majority ranging from 0.1 to 10 jum in diameter.1 2 Particles 0.25 to 5 /jm in diameter
are retained in the lung, with a maximal retention of 80 percent of 1 jum particles and less than 5 percent
retention of particles smaller than 0.1 /urn or larger than 5 /urn.1 23 Particles greater than 5 jum are trapped in
the upper respiratory tract.123 PPOM in the air appears to be adsorbed on particles with a size range of 0.1
tolOjUm and should therefore be deposited throughout the respiratory tract.28 Falk and co-workers
demonstrated that BaP was present in soot samples of respirable particle size, but that when soot was
recovered from human lungs at autopsy, BaP could not be detected.' 24
The BaP-hematite-Syrian hamster model has been used to elucidate information on the role of carrier
particulate and on the elution of hydrocarbon carcinogens from the particle. Clearance studies have shown
that retention of intratracheally injected BaP is proportional to the amount of hematite employed and that
the rate of elimination is skewed with time, suggesting a prolonged retention due to the presence of the
particle.59 The elimination of BaP has also been related to the size of the particle to which it is adsorbed,
since it is eliminated more slowly from smaller particles.54 In experiments employing tritiated BaP in
hamsters, clearance of radioactivity from the lung after a 14-day period was significantly slower when the
BaP was incorporated on carbon or asbestos than when BaP was used alone.125 It appears that the carrier
particle prolongs the residence time of the carcinogen in the lung. It is not clear exactly how this is
accomplished, nor is it known to what degree this takes place in nature.
The role of macrophage, surfactant, mucus, cilia, blood, and lymphatic clearance mechanisms of the
carcinogen and particle should be clearly defined because it is possible that the level, or size distribution, of
total particulate in the atmosphere may be more important in carcinogenesis than the percentage of that
total that is carcinogenic hydrocarbon.
Hilding has proposed that changes in ciliary movement and mucus viscosity are caused by nonspecific
airborne irritants, and that these changes are most important in failure to clear carcinogens.1 26 Laskin's33
demonstration of enhanced tumor production with S02 and BaP may be an example of the nonspecific
irritant effects proposed by Hilding,1 26 or it may be due to another mechanism. Palmer and associates have
shown that ozone decreased the amount of BaP hydroxylase enzyme in lung12 7 and tracheal mucosa.12S
6.1.3.2 Distribution, Excretion, and Metabolism ofPAH—\n 1936, Peacock injected colloidal suspensions
of anthracene, dibenz[a,h] anthracene, and BaP intravenously into animals and found that the compounds
were rapidly cleared from the blood and excreted into the bile.129 The use of radioactive tracer techniques
has confirmed this observation130 and established that biliary excretion also follows intratracheal
injection.131 Maly has evaluated the content of dibenzo[a,lj pyrene (1,2-3,4-dibenzpyrene) in the urine of
smokers, nonsmokers forced to smoke, and nonsmokers.132 He found that levels of this metabolite were
0.0 Mg/hter in nonsmokers, 0.3 jug/liter in smoking nonsmokers, and 1.1 jug/liter in active smokers. The
identification of this metabolite in urine may lead to a useful screening test for hydrocarbon exposure. It
also indicates that higher metabolite levels are seen in people who have had repeated previous exposures and
probably have higher levels of an enzyme that converts contaminants in cigarette smoke to this metabolite.
Most work on POM metabolism has been done in animals or in vitro systems, but in no case have all the
metabolites of any hydrocarbon been identified.28 Sims has identified the following metabolites of BaP:
the monophenols (3- and 6-hydroxy), the diphenols (3,6- and 1,6-dihydroxy), quinones (1,3-dione and
1,6-dione), and-two dihydrodiols (1,2- and 9,10)133 None of these metabolites is carcinogenic. It is
postulated, however, that metabolic activation is probably necessary to induce cancer. It has been proposed
that epoxides are formed from hydrocarbons and that these are the carcinogenic form.134 Recently Sims
has synthesized benz[a] anthracene 8,9-oxide, an epoxide; when this was added to rat liver homogenates, a
dihydrodiol was formed, as when benz [a] anthracene was metabolized in this system.135 Similarly,
Effects on Human Health 5.5
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synthesized K-region epoxides are more active in malignant in vitro transformation than are the parent
hydrocarbon, its dihydrodiols, or its phenols.13 6
The primary enzyme system for metabolism of PAH is the microsomal aryl hydrocarbon hydroxy-
lase.137"139 It converts these compounds to the derivatives just discussed. This system is inducible with
PAH and with a variety of other materials.137"140 The level of enzyme and inducibility are genetically
determined,28 and can also be induced transplacentally.140"142 It has also been shown that tumorogenesis
is decreased by preinduction of this enzyme.143'144 This enzyme can be inhibited with 7,8-benz-
oflavone2 8 and with ozone.J 2 7>'2 8 Obviously, this enzyme system plays a very important role in biologic
handling of PPOM.
6.1.3.3 Chemical Carcinogenesis at Molecular Level-Chemical carcinogens transform normal cells into cancer
cells.145'146 Mondal and Heidelberger have very efficiently transformed individual normal cells into
malignant cells with 3-methylcholanthrene.147 It has also been postulated that all chemical carcinogens can
act through intermediary oncogenic viruses.148 Some examples of this have been found.94'95 When viruses
have not been detected, however, their participation is not definitely disproved. Nevertheless, whether
viruses are involved or not, it is still the chemical that triggers the process.
If chemical carcinogens themselves produce cancer directly, then the mechanism is by mutation or
nonmutation (derepression of genetic information already contained in the cell). Mutation requires
interaction with DNA, change in the primary sequence, and perpetuation of that change. Chemical
carcinogens (or derivatives of these carcinogens) have been found to bind covalently with DNA, RNA, and
protein of target tissues.149 Binding of PAH to mouse skin DNA and RNA has been studied, but the
chemistry of this binding is not yet known. lso"152 The binding of PAH to proteins also has been
studied.1 S3>1 S4 It is postulated that this binding may depress an oncogene which results in carcinogenesis
by a nonmutational mechanism.149 The finding of fetal antigens in several human tumors is evidence in
support of this theory;1 S5>1 s6 however, that theory is by no means universally accepted. Hydrocarbon-
induced tumors have been shown to acquire new transplantation antigens.1 S7)1 s9 The significance of these
antigens to the process of carcinogenesis remains unexplained.
6.1.3.4 Modification of Host Factors in Relation to PPOM Exposure—The immune system may be involved
in two aspects of chemical carcinogenesis—immunity to chemical carcinogens and immunity to transformed
cells. Peck and Peck showed a tumor inhibition of over 50 percent when rats were first sensitized with a
carcinogen-protein conjugate and then given a chemical carcinogen.160 Earlier studies of this type were
done with similar but less spectacular results.1 6 l'' 62
The role of age in carcinogenesis testing has been investigated using screening studies in neonates, but few
studies have been done in aged animals. One study suggested that aged animals were more susceptible to
skin carcinogenesis.1 63 Others have seen no differences between young adult and aged animals,164 and still
another study showed a decline in carcinogenesis in aged animals.165 Neonates have been shown to be an
effective screening bioassay for carcinogens, and studies are needed into the mechanism of their increased
susceptibility.
The role of nutrition in chemical carcinogenesis has had some study especially with regard to the role of
vitamin A, which appears to have some protective effect on epithelial tissues.166 It has also been observed
that obesity may be coincident with greater susceptibility to develop cancer.167'165 Another association
of diet and chemical carcinogenesis involves the dietary induction of aryl hydrocarbon hydroxylase
enzyme.28 However, it does not appear that diet will be among the most significant factors involved in
chemical carcinogenesis.
The role of infection in respiratory carcinogenesis has been studied, with conflicting results. Campbell
found a reduction in the incidence of tar-induced lung tumors after viral infection, but the number of mice
in the study was small.169 Nettesheim et al found that influenza virus decreased the incidence of lung
tumors induced by gasoline.81 Steiner and Loosli found that the virus decreased the incidence of
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spontaneous lung tumors.170 In contrast, Kotin and co-workers found that viral infection increased the
incidence of lung tumors induced by gasoline fumes,79'80 and Imagawa et al. found the same to be true
with urethane.171 Despite the conflicting results, the possibility of infection playing a role in
carcinogenesis is an attractive hypothesis. The alteration of clearance mechanisms, the effects of infection
on the trachea-bronchial lining cells, and the interactions involved in the immune status during infection are
poorly understood in relationship to in vivo handling of PPOM.
The role of radiation in chemical carcinogenesis has been investigated experimentally and epidemiologically.
Epidemiologic studies on uranium miners have shown a higher incidence of cancer in miners who are
smokers; a synergistic effect between exposure to alpha radiation and components of cigarette smoke was
implied.172'173 However, experimental studies using BaP or 7,12-dimethylbenz[a] anthracene and either
external irradiation174'175 or polonium-21028'176 have shown additive effects of this combination.
Further studies on the interaction of alpha radiation particles and PAH compounds would provide data to
help assess any adverse health effects resulting from the exposure to a combination of these materials.
& 1.3.5 Summary of PPOM Interaction-Although some work has been done on every level of PPOM
interaction with biologic materials, definitive work remains to be accomplished in most of these areas. Safe
exposure levels in the presence of "inert" particles, irritants, metabolic inhibitors, infection, immunosup-
pression, and irradiation are not known.
6.1.4 Determination of Dose-Response Patterns in Animals
Saffiotti et al. have recently evaluated respiratory tract carcinogenesis induced in hamsters by different
numbers of administrations of BaP and hematite.177'178 A positive dose-response relationship was
demonstrated. A total dose of as low as 15 mg produced a 15 percent tumor incidence, with high doses
yielding higher incidences. On this basis, it was felt that valid results could be obtained with lower doses
and larger numbers of animals. However, the usefulness of such data is limited relative to problems of air
pollution, because intratracheal injections are not physiologic, and unequal distribution in the lung is
common.179 No attempts to equate dose and response have been carried out by inhalation studies which
would avoid distribution problems. Several investigators have attempted to extrapolate a conservative safe
dosage of an agent whether or not carcinogenic activity was found.180'181 This extrapolation based in
statistics is at best a poor guess of the actual situation, but at present is the best extrapolation available.
The question of whether a threshold concentration exists in the environment below which no adverse
health effects are produced is very important. The National Academy of Sciences document considered this
question only briefly since experimental approaches are at present very expensive and complex.28
However, the alternatives in setting air quality standards are: (1) recommending these standards on the basis
of epidemiologic studies alone, which will require extensive investigation; (2) recommending arbitrary
standards based on no biologic investigation; (3) recommending a level of zero for any carcinogen in the air,
based on screening studies; and (4) setting no standard at all until adequate information is available.
6.1.5 Teratogenesis and Mutagenesis
A very limited amount of work has been done on the teratogenic and mutagenic effects of pollutant
compounds found in the ambient atmosphere. The following material extracted from the NAS report28
reflects the current state of knowledge regarding these subjects.
There are no known data on teratogenicity testing, by any route, of air pollutant PPOM.
A method of detecting point mutations in mammalian somatic cells is to use in vitro tissue-culture systems.
The potential of using mammalian somatic cells in vitro for genetic studies has long been recognized, but
substantial progress was not made until improved and simplified techniques for mammalian cells were
Effects on Human Health 6-7
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developed by Puck and associates.182'183 These methods made possible quantitative analysis of genetic
variations in cell populations via the plating technique for mammalian cells.
It was demonstrated that gene mutations are induced by treatment of Chinese hamster cells in cultures with
alkylating agents184''85 In addition, physical agents (such as x-rays and ultraviolet radiation) and
chemical agents (such as carcinogens) have been shown to induce forward and back mutations at several
genetic loci in these cells.186'190 Thus, in vitro cell culture offers a new system for testing the
mutagenicity of chemicals in human environment. Whether somatic mutation may cause cancer can now be
reexamined more critically, because both carcinogenesis and mutagenesis have been shown to occur
experimentally in the same target cell system in vitro. Furthermore, human somatic cells from normal and
neoplastic tissues can also be tested directly.
Chu and co-workers have tested the mutagenicity in Chinese hamster cell cultures of a few selected groups
of chemical carcinogens and their related compounds and derivatives.189 Table 6-1 lists the compounds
tested and their relative carcinogenicity (based on animal studies) and mutagenicity. The genetic marker
assayed in the hamster cells was the change from 8-azaguanine sensitivity to resistance. The results obtained
thus far indicated that there was direct relation between the degree of carcinogenicity and mutagenicity and
that metabolically activated derivates of the test compounds often played important roles in mutagenic
action. It was recently demonstrated that epoxides of PAH are much more mutagenic to mammalian cells
than are the corresponding hydrocarbons, dihydrodiols, and phenols.1
Parallel results have been obtained in the induction of mutations with the same series of compounds at the
adenine-3 region of Neurospora.} 92 Similarly, N-acetoxy-2-acetylaminofluorene has been shown to be
mutagenic in T4 bacteriophage,1 93 Bacillus subtilis,1 94 and Escherichia coll] 9S
Clearly, these results are promising, but more data using more representative compounds and additional
genetic loci will be needed before a more definitive conclusion may be drawn. The use of mammalian cells
in vitro for a combined and coordinated test for chemical mutagenesis and carcinogenesis may be expected
to yield significant information on cellular mechanisms of cancer. However, data on mutagenesis derived
from somatic cells in vitro are limited by present inability to identify factors involved by conventional
genetic techniques. There are no published data on mutagenicity testing of air pollutants by inhalation.
Table 6-1. RELATIVE CARCINOGENICITY AND MUTAGENICITY
OF SELECTED COMPOUNDS28 '189
Test compound
Benzofe] pyrene
Benzo[a] pyrene (BaP)
3-Hydroxybenzo[a] pyrene
Dibenz[a,c] anthracene
Dibenz[a,h] anthracene
7,12-Dimethylbenz[a] anthracene
2-Acetylaminofluorene
N-Hydroxy-2-acetylaminofluorene
N-Acetoxy-2-acetylaminofluorene
Carcinogenicity8
i+
Mutagenicity
±
6-8
—: not carcinogenic (or mutagenic)
±: uncertain or weakly carcinogenic (or mutagenic)
+ : carcinogenic (or mutagenic)
+++: strongly carcinogenic (or mutagenic)
PARTICULATE POLYCYCLIC ORGANIC MATTER
59
-------
6.2 EP1DEMIOLOGICAL APPRAISAL
6.2.1 Introduction
Some components of PPOM can be deleterious to human health, but considerable doubt surrounds such
questions as: Which specific PPOM compounds are most harmful? What concentrations of PPOM are
harmful? How long must one be exposed to PPOM before his health is endangered? Can PPOM alone affect
health? Epidemiology is an essential instrument for answering these questions, but it alone cannot answer
them completely. Firm answers will be found only through the joint efforts of the epidemiologist, the
toxicologist, the clinician, and the environmental engineer.
6.2.2 Epidemiologic Findings
The illnesses usually related to exposure to PPOM are cancer of the skin and lung. Nearly all the findings
have been made in studies of occupational exposure to the combustion products of carboniferous material.
In all these studies, PPOM concentrations have been very high and exposures prolonged. In most cases, the
actual concentrations to which the subjects were exposed were not known, nor could the chemical
compounds of the occupational exposure environment be characterized with a high degree of certainty.
Of course, in occupational exposure, the dose of PPOM is far greater than in ambient air. In gas works, the
concentration of BaP has been estimated at 3 /jg/m3 ; above coke ovens, it may reach levels of 216 Mg/m3.
In even the most polluted ambient air, the annual average BaP concentration rarely exceeds 0.01 /ug/m3 •
PPOM is produced mainly by the combustion or volatilization of fossil fuels. Most of the industry-related
cancer experiences have been cases involving combustion or distillation of coal products. In gas-works retort
houses in England, BaP concentrations of 3 to 216 ng/m3 were measured. These concentrations were 100
to 10,000 times higher than the normal BaP level in London.28
In one study, British gas workers employed for at least 5 years were divided into a high-exposure and a
low-exposure group. The lung cancer incidence in the high-exposure group was 69 percent greater than in
the control group. Coke oven workers also have experienced an increase in the incidence of lung
cancer.196'198
For two centuries, it has been recognized that soot may cause scrotal cancer. Despite this knowledge,
chimney sweeps were shown to experience excess scrotal cancer as recently as 1964.199 Wax pressers with
prolonged exposure to crude wax have been shown to have increased scrotal cancer rates.200 Other
substances associated with excess skin cancer include tars, shale oil, and cutting oil.201 '203
In addition to cancer, other cutaneous disorders have been linked to PPOM. Among these are nonallergic
and allergic dermatitis, phototoxic inflammatory reactions, pilosebaceous responses, and pigmentation
disorders.204'206 No skin disorder has yet been demonstrated to result from exposure to PPOM in ambient
air.
A number of epidemiologic studies have linked PPOM to nonoccupational neoplastic-pulmonary disease.28
Most of them generally agree that, in American males, the urban lung cancer death rate is about twice the
rural rate, even after adjustment for differences in smoking habits. These studies have attributed at least
part of the excess mortality to urban air pollution. In the United Kingdom, Stocks found increasing
standardized mortality ratios for lung cancer with increasing density of dwelling units.207 In an area near
Osaka, Hitosugi made a detailed study of the differences in lung cancer death rates between people living in
high industrially polluted-sections and people living in relatively low-polluted sections.28 The results listed
in Table 6-2 indicate that lung cancer death rates among male smokers of comparable smoking habits were
higher in sections of high industrial pollution. The largest urban-rural difference in lung cancer deaths was
found among the lightest smokers.
Effects on Human Health 6-9
-------
Table 6-2. LUNG CANCER DEATH RATES FOR MALES AND FEMALES,
AGE 35-74, BY SMOKING CATEGORY AND AIR POLLUTION LEVEL
Smoking category
Males
Nonsmoker
Exsmoker
Smoker (ciga-
rettes/day)
1 to 14
1 5 to 24
>25
Females
Nonsmoker
Exsmoker
Smoker (ciga-
rettes/day)
1 to 14
1 5 to 24
Lung cancer death rate per 100,000 persons3
Low
pollution
11.5
(5)
26.2
(11)
10.6
(9)
14.7
(18)
36.3
(19)
4.6
(15)
12.4
(2)
19.7
(13)
12.4
(1)
(0)
Intermediate
pollution
30
.0
(1)
42.6
(7)
14.2
(10)
19.1
(17)
15.8
(4)
6.9
(12)
52.6
(2)
16.5
(6)
23.1
(2)
(0)
High
pollution
4.9
(1)
61.7
(7)
23.5
(14)
27.0
(17)
46.4
(6)
3.8
(6)
124.0
(3)
15.3
(5)
24.0
(1)
(0)
Total
7.9
(7)
36.0
(25)
15.3
(33)
19.1
(52)
44.0
(32)
4.9
(33)
13.3
(6)
17.6
(24)
19.7
(4)
(0)
Numbers in parentheses are numbers of deaths.
Stocks and Campbell performed a similar study in the Liverpool area. Table 6-3 lists their results The
conclusions from their study agreed with those reached by Hitosugi-that lung cancer death rates were
higher in the urban areas than in the rural areas for each smoking category. Stocks and Campbell, along
with Hitosugi, pointed out that the most prominent urban-rural difference in lung cancer death rates was in
the group of lightest smokers. The urban-rural difference among the heavier smokers was less pronounced.
6-10
PARTICULATE POLYCYCL1C ORGANIC MATTER
-------
Table 6-3. LUNG CANCER DEATH RATES FROM MID-1952 TO MID-1954 BY AGE,
SMOKING CATEGORY, AND POPULATION AREA3
Smoking
category
Nonsmoker
Pipe smoker
Cigarette smoker
Light
Moderate
Heavy
Number of
deaths
Lung cancer death rates per 100,000 persons
Age 45-54
Rural
0
0
69
90
117
16
Mixed
0
0
57
83
214
26
Urban
31
104
112
138
205
124
Age 55-64
Rural
0
30
70
205
626
26
Mixed
0
59
224
285
362
56
Urban
147
143
376
386
543
230
Age 65-74
Rural
70
145
154
362
506
27
Mixed
0
26
259
435
412
36
Urban
336
232
592
473
588
183
SDRb Age 14-74
Rural
14
41
87
183
363
68
Mixed
0
25
153
132
303
118
Urban
131
143
297
287
394
539
Percent
difference0
89.3
71.3
70.7
36.2
7.9
Percent
difference aer
BaP unitd
12.8
10.2
10.1
5.2
1.1
w
c
W
S
n
&3
Derived from Stocks and Campbell.28
Standardized death rate.
Cc , ,nn (urban SDR) - (rural SDR)
Equals 100x
Equals
urban SDR
Percent difference
7.0 (Mg BaP per 1000 m3)
-------
In a study of U S residents, Haenszel categorized subjects by similarities in smoking habits, age, sex,
location and duration of residence.28 His results (see Table 6-4) indicate that lung cancer death rates
among males adjusted for age and smoking habit, were higher in urban areas than in rural areas. In contrast
to previous studies, Haenszel pointed out that the greatest urban-rural difference in lung cancer death rates
in males was among the heaviest smokers. The controversy here is over the degrees of difference and not
over the fact that differences existed among comparable smokers located in different areas. Table 64 also
shows that lung cancer death rates for lifetime urban residents was twice that of lifetime rural residents-m
close agreement with conclusions from previous studies. Nevertheless, most urban-rural comparison surveys
have not carefully considered differences in smoking habits and other environmental covanates.
Occupational exposure is probably an extremely important factor. The necessity for caution against
overstating the effect of ambient pollution is exemplified by the Nashville study, which did not show a high
correlation between lung cancer and air pollution.208 In a study in Buffalo, Winkelstein et al also failed to
find a consistent relation between air pollution and lung cancer deaths.
Though urban air often contains PPOM, there is as yet no clear evidence that urban levels of PPOM are
carcinogenic to man. In many instances, BaP has been used as a practical index of air pollution because it:
(1) is a solid in air, and thus it can be adsorbed on particles and collected for assay; (2) can be correlated
with other polycyclic compounds; and (3) is a known carcinogen in animals and a suspected one in man.
However, one must be cautious in drawing conclusions about the health effects of BaP. It may be-shown
that a certain rise in BaP levels is associated with a certain rise in mortality. When BaP levels are high,
however, several other pollutants also tend to be abundant-notably hydrocarbons, total suspended
particulates, and sulfur dioxide. All of these substances are present in coal smoke.
Caution is further warranted by the fact that the correlation of BaP to other urban pollutants varies among
cities. BaP and other PPOM are formed in highest concentration in reducing atmospheres. Sulfur dioxide is
a combustion product of high-sulfur fossil fuels. Thus, the BaP/sulfur dioxide ratio will be very high with
combustion of low-sulfur coal and very low with complete combustion of high-sulfur coal. In either
situation, lung cancer mortality might be affected, but one cannot necessarily ascribe the excess mortality
to the same pollution components in both cases.
Several human cancers involving organs other than skin and lung have been associated with particulate air
pollution. In the Nashville study, some correlation was demonstrated between the soiling index and cancers
of the bladder, esophagus, and prostate. There was also a relationship between dustfall and stomach cancer.
It would be most premature to ascribe these tumors to a specific pollutant such as BaP or another
polycyclic compound.
Table 6-4. STANDARD LUNG CANCER MORTALITY RATIOS IN WHITE MALES IN URBAN
AND RURAL AREAS, ADJUSTED FOR AGE AND SMOKING HISTORY3
Standard mortality ratio by duration of residence
(years)
Current
residence
Urban
Rural
Al!
durations
113
79
Less than
1
166
154
1-9
107
88
10-39
117
83
Over
40
177
75
Lifetime
100
50
a 28
Derived from Haenzel eta/.
Lung cancer base death rate = 78.2.
6-12
PARTICULATE POLYCYCLIC ORGANIC MATTER
-------
Although little evidence relates to nonneoplastic diseases, some provocative findings have been made. For
example, English coal gas workers exposed to high levels of PPOM— especially BaP—had an even greater
excess of chronic bronchitis than of lung cancer.207 BaP did not appear to have much bearing on the
incidence of pneumonia, and it was concluded that BaP is not an important contributor to chronic
bronchitis mortality.
6.2.3 Discussion
To date, epidemiologic findings implicate PPOM in the production of skin and lung cancers. Although most
authors cite BaP as the primary human carcinogen, this conclusion is probably premature. A great deal of
work remains in defining more completely the roles of specific polycyclic compounds in producing human
disease. For example 7,12-dimethylbenzfa] anthracene has been implicated as an animal carcinogen, but its
role as a human carcinogen has not been determined.
Studies to date have suffered from the inability to define the individual components of local air pollution.
A symptom of this inability has been the tendency to ascribe the total air pollution effect to BaP alone. In
some cases, it may be reasonable to use BaP as an index of PPOM pollution, but it must be borne in mind
mat PPOM has never been shown to cause human lung cancer, per se, and has never even been associated
with skin cancers of any kind. Many current studies, such as those of EPA's CHESS program (The
Community Health and Environmental Surveillance Study) are making a concerted effort to characterize
local air pollution profiles. For the present, the epidemiologist is not justified in making broad
generalizations about local findings.
The problem of defining the role of PPOM is complicated by the phenomenon of cocarcinogenesis.210 It
has often been found that even a potent carcinogen is relatively inactive unless coupled with one or more
other substances (cocarcinogens). Furthermore, cocarcinogens can greatly shorten the latent period of
carcinogenesis. Known cocarcinogens include ultraviolet radiation, epoxides, lactones, asbestos, and
aromatic hydrocarbons; suspected cocarcinogens include sulfur dioxide or sulfates, nitrogen oxides, and
ozone. Clearly, present data do not warrant well-founded long-range conclusions. The whole spectrum of
airborne hydrocarbons has not been assessed for possible interactions with polycyclic hydrocarbons. The
degree to which a particular concentration ratio of sulfur dioxide (or other gaseous or particulate
pollutants) to PPOM is conducive to tumor formation is not known. It may be that an atmosphere with
fairly low concentrations of both PPOM and sulfur dioxide may result in adverse health effects.
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199. Annual Report of Her Majesty's Chief Investigator of Factories on Industrial Health, 1964. London,
H. M. Stationery Office, 1969. 31 p,
200. Hendricks, N. V.,etal. Cancer of the Scrotum in Wax Pressmen. 1. Epidemiology. A.M.A. Arch. Ind.
Health. 79:524-529, 1959.
201. Hueper, W. C. Occupational Tumors and Allied Diseases. Springfield, 111., Charles C. Thomas, 1942.
896 p.
202. Scott, A. Cancers in Mineral Oil Refineries. In: Report of the International Conference on Cancer,
London, 17-20 July, 1928. New York, William Wood and Company, 1928. p. 275-279.
203. Cruickshank, C. N. D., and J. R. Squire. Skin Cancer in the Engineering Industry from the Use of
Mineral Oil. Brit. J. Ind. Med. 7:1-11, 1950.
204. Schwartz, L., L, Tulipan, and D. J. Birmingham. Occupational Diseases of the Skin, 3rd Ed.
Philadelphia, Lea and Febiger, 1957. 981 p.
205. Dunn, J. E., and F. S. Bracket!. Photosensitizing Properties of Some Petroleum Solvents, Ind. Med.
77:303-308, 1948.
206. Suskind, R. R. Acne: Occupational. In: Traumatic Medicine and Surgery for the Attorney. Vol. 6.
Psychiatry. Skin and Its Appendages. Cantor, P. D. (ed.). Washington, D. C., Butterworth Inc., 1962,
p. 563-573.
207. Stocks, P. Cancer and Bronchitis Mortality in Relation to Atmospheric Deposit and Smoke. Brit.
Med. J. 7:74-79, 1959.
208. Hagstrom, R. M., H. A. Sprague, and E. Landau. The Nashville Air Pollution Study. VII. Mortality
from Cancer in Relation to Air Pollution. Arch. Environ. Health. 75:237-248, 1967.
209. Winkelstein, W., et al. The Relationship of Air Pollution and Economic Status to Total Mortality and
Selected Respiratory System Mortality in Men. I. Suspended Particulates. Arch. Environ. Health.
74:162-171, 1962.
210. Suskind, R. R., and A. W. Horton. Etiologic Factors and the Pathogenesis of Premalignant and
Malignant Lesions of the Skin. In: The Human Integument: Normal and Abnormal. Rothman, S.
(ed.). Washington, D. C., American Association for the Advancement of Science, 1959, p. 171-192.
Effects on Human Health 6-25
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7. OTHER (WELFARE) EFFECTS
7.1 ECOLOGICAL
Ecosystems are affected by higher concentrations of POM, such as occur near urban centers, petrochemical
industries, and fossil-fuel-utilizing sources. The effects of POM are evaluated in the general ecological
context, including the effects on soil, water, biological components, and their relationship within
environmental systems.
Naturally functioning ecosystems may contribute PPOM either as solids or liquid aerosols. Generally, the
contribution from natural sources enters the atmosphere in amounts that do not cause major air pollution
problems.1 However, the total POM produced by natural sources is unknown. Since POM may exist in
relatively pure form on particles, it can be readily absorbed-especially when animals may be
receptors—through ingestion, inhalation, or direct skin contact.
In whatever form POM reaches the soil, water, or the biological receptors, its deposition and eventual fate
will affect the receptor.
Synergistic reactions, the ramifications of which are virtually unknown, are possible between POM and
other agents. It has been shown in hamsters and other test animals that ionizing radiation along with some
chemical carcinogens will increase the incidence of lung cancer.2
There is voluminous literature on the fate of PAH in experimental animals. A large number of PAH
compounds are capable of being metabolized by animals.1 The majority of the carcinogens of the PAH type
are derivatives of phenanthrene, but not all derivatives of phenanthrene are carcinogenic.3
POM has not been shown to produce tumor-like reactions in plant tissues; however, it is a suspect in the
case of cultivated mushrooms.4
No information was found to indicate that carcinogenic PAH affect vegetation. Other PAH, however, are
produced by plants. Evidence suggests that some individual PAH compounds may behave as plant
hormones.5
POM has been reported in many plant and plant products such as tobacco smoke; snuff; peat; wood soot;
pulp mill stack gases; roasted coffee beans; plant tissues; pyrolyzed cellulose, lignin, and pectin;
wood-smoked foods; incinerator effluents; and marine flora and fauna.2 It may also be produced when
foods are heated during preparation.
Plants may also synthesize POM, thus contributing to biological intake through food chains.2 However,
uptake of polycyclic compounds from the soil is a greater source of POM. The incidence of human gastric
cancer and intestinal neoplastic disease correlates with ingestion of plants bearing POM.2 Most atmospheric
hydrocarbons from vegetation are thought to be terpenes.
Benzopyrenes have been found in remote rural soils, in tree leaves, and in roots and shoots of some cereal
crops. They also have been detected in decaying litter and other similar organic matter and have been
shown to be in soil solutions, where they are subject to uptake by plants.2
7-1
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In addition to the POM from industrial processes, pesticides and derivatives thereof applied to crops
contribute POM to the environment; the greatest impact is on food chains or on soil microbiota.
POM can have a direct effect upon soil microorganisms. It is well documented that the microbial
populations of soil can be altered by the deposition of hydrocarbons. The response from a particular soil
type, whether rural or urban, depends on the types of microorganisms present. Successional changes in
microbial populations occur over a period of time after the soil has been enriched with POM/ 'b
Many PAH compounds which are carcinogenic to man can be utilized by a variety of microorganisms
common in polluted soil and water.1 Both bacteria and yeasts may utilize BaP, and Shabad and coworkers
noted an enrichment effect in soils contaminated with BaP.7 Some strains of soil bacteria are capable of
absorbing and concentrating BaP, whereas others destroy it, i.e., transform it into derivatives. BaP in soil
may therefore be taken up by plants or utilized or transformed by microorganisms.
Similar types of problems have been found in aquatic ecosystems concerning sediment deposition and POM
distribution and actions within the biological components.8
It is possible that attenuation of light or visibility may either interfere with the normal photosynthetic
processes of vegetation or will affect other metabolic processes. The impact of PPOM will depend on
ambient atmospheric conditions, particle size, and the differential ability of receptors to accumulate this
matter. For example, Neuberger and coworkers suggest that conifers are better natural filters than deciduous
trees.9 It is also known that vegetation in general adsorbs more particles of 20 /urn or less in size than of
those above that size.10 The size range of PPOM is from a few tens of Angstroms to hundreds of
micrometers.2
7.2 MATERIALS
No evidence has been found of effects of ambient levels of PPOM on materials. Based on the nature of this
type of pollutant, two possible effects are suspected:
1. POM may cause inorganic particulate matter to adhere to material surfaces and so contribute to
soiling; or
2. Polymeric material such as vinyl paints may become susceptible to solvent-actions of POM.
Given ambient concentrations of PPOM, these are expected to be relatively minor effects.
7.3 REFERENCES
1. Garner, J. H. B. Hydrocarbon Emission Effects Determination: A Problem Analysis. National
Environmental Research Center, Research Triangle Park, N.C. 1972. 108 p.
2, Particulate Polycyclic Organic Matter. National Academy of Sciences, Washington, B.C., 1972. 361 p.
3. Badger, G. M. The Carcinogenic Hydrocarbons: Chemical Constitution and Carcinogenic Activity Brit
J. Cancer. 2:309-350, 1948.
4. Evans, H. J. The Effects of External Agents on Differentiation in the Cultivated Mushroom. Ph.D.
Thesis.-University College of Wales. 1955.
5. Andelman, J. B., and M. J. Suess. Polynuclear Aromatic Hydrocarbons in the Water Environment Bull
W.H.O. 4J:479-508, 1970.
7-2 PARTICULATE POLYCYCLIC ORGANIC MATTER
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6. Rasmussen, R. A. Personal communication. 1972.
7. Shabad, L. M., Y. L. Cohan, A. Ya. Khessina, H. P. Schubak, and G. A. Smirnov. The Carcinogenic
Hydrocarbon Benzo [a] pyrene in the Soil. J.Nat. Cancer Inst. 47:1179-1191, 1969.
8. Zobell, C. E. Sources and Biodegradation of Carcinogenic Hydrocarbons. Proceedings Joint Con-
ference on Prevention and Control of Oil Spills. New York, American Petroleum Institute, 1971.
9. Neuberger, H., C, L. Hosier, and W. C. Kocmond. Vegetation as Aerosol Filter. In: Biomeleorology.
Tromp, S. W., and W. H. Weihe (ed.). Oxford, Pergamon Press, Ltd., 1967. p. 693-702.
10. Witherspoon, J. P., and F. G. Taylor, Jr. Interception and Retention of a Simulated Fallout by
Agricultural Plants. Health Phys. 79:493-499, 1970.
Other (Welfare) Effects 7-3
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8. CONTROL TECHNOLOGY
8.1 INTRODUCTION
Very little specific test information is available on the effectiveness of techniques to control POM
emissions. Control techniques are based largely on considerations of the mode of formation and physical
and chemical characteristics of these materials.
Theoretical considerations suggest that much of the POM will be associated with particulates. Therefore,
the use of conventional particulate collection equipment may remove much of this pollutant. Because most
POM is thought to be associated with the submicron sized particles, however, preference should be given to
equipment capable of removing such particles—for example, electrostatic precipitators, high energy
scrubbers, or bag filters. Because of their relatively inefficient collection of particles smaller than 5 ^m,
cyclones do not appear to be highly applicable to removal of POM; they may have value upstream of an
electrostatic precipitator, however.
Electrostatic precipitators appear to offer considerable promise because of their ability to remove small
particles. Dry precipitators have difficulty handling sooty and tarry particulates. Wet precipitators,
however, have been developed to remove such particles and have been used extensively on larger utility
boilers. Considerable research is still needed to improve these devices so they will be uniformly effective in
the fine-particle range.
Wet scrubbers appear to offer considerable advantages in the removal of POM. Because of their relatively
long residence times, low-energy devices such as spray towers may be used as condensers for VPOM.
Following this with a high energy device such as a venturi scrubber should be highly efficient in removing
fine particulates.
Fabric filter bag collectors possess unequaled ability to remove submicron particles, but they may suffer
from binding problems when handling the sooty, tarry particulates often associated with high organic loads.
The efficiency of these devices for collecting PPOM will depend upon the particle size distribution of the
PPOM itself and/or the particle size distribution of other particles upon which the POM is adsorbed.
In the absence of adequate information on size distribution of PPOM, it can only be said that the more
efficient the gas-cleaning equipment is in removing the entire size range of all particulates, the more
efficient it will be in collecting PPOM. It is suspected, however, that PPOM is associated with incomplete
combustion. The size range for tobacco smoke, resin smoke, carbon black, and combustion nuclei is from
0.01 to 1 ;um. Thus, it is anticipated that the PPOM will be mainly in this size range.
In selecting a technique or combination of techniques for any given application, and in selecting the
equipment type within each technique, three broad factors must be considered:
• The characteristics of the cleaning equipment required to remove POM.
• The effects of tarry and viscous material on the gas-cleaning equipment.
• The effects of other components in the flue gas stream on the gas-cleaning equipment.
8-1
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In summary, POM associated with gross particulates may be removed by conventional participate removal
equipment designed in accord with conventional design procedures. The extent of this removal will depend
upon both the ratio of total POM to total particulates, and also upon the distribution of POM among the
size fractions of total particulate matter. At present, adequate control technology does not exist for fine
particulates. So, if as anticipated, PPOM lies mainly in the fine range, control technology has not been fully
developed.
8.2 STATIONARY COMBUSTION .EMISSIONS
Techniques that will control emissions of POM from stationary combustion sources may be broadly
categorized as follows:
• Good design • Clean fuels
• Good practice • Gas cleaning
• Process modification • Source shutdown
• Energy substitution • Energy conservation
Good design, good practice, process modification, and energy substitution are all techniques aimed at
improving combustion in stationary fuel combustion sources and thus preventing the formation of POM. In
evaluating possible control techniques for a particular combustion source or group of sources, these
techniques merit special consideration. Not only will they make the most economical use of fuel, but they
will also help reduce the emission of other pollutants such as carbon monoxide and gaseous hydrocarbons
that result from incomplete combustion. It must be borne in mind, however, that over-application of
techniques to promote good combustion—high flame temperatures and excessive amounts of air—may, for
example, result in increased emissions of nitrogen oxides.
Clean fuels offer a unique control possibility. Considerable interest has developed in the "hydrogen fuel
system" in which hydrogen would become a major substitute for presently used fossil fuels. Hydrogen
combustion yields only water. Carbon monoxide may also produce no particulate matter in combustion. If
so, "low-Btu gas',' a mixture of carbon monoxide and hydrogen, may have as much potential as natural gas
as a minimum-PPOM source of energy.
The sixth technique, gas cleaning, may find application where, for any reason, the first five techniques
cannot be applied or cannot achieve the reduction needed in PPOM. Gas-cleaning equipment will probably
be installed in conjunction with one or more of the first four techniques. Since gas-cleaning equipment will
also remove other pollutants, the benefits derived must be taken into consideration in evaluating gas
cleaning as a technique for the reduction of POM emissions.
The seventh technique, source shutdown, is a drastic control technique, but it should not be completely
disregarded. Source shutdown is useful for control of particulate emissions when air pollution levels
threaten the public health in emergency episodes and for control of emissions when lawful orders to abate
are ignored.
The eighth technique, energy conservation, limits POM emissions by reducing the amount of fuel burned
for a given energy output. It differs from the first technique, good design, in that it is concerned not with
the efficiency of the combustion process itself, but with the subsequent process steps used in converting the
heat released by the combustion process into the form of energy required. This technique does not appear
to have application in the reduction of emissions from a particular source at a particular time since, at
present, the technology of energy conversion is being improved only slowly.
8-2 PARTICULATE POLYCYCLIC ORGANIC MATTER
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8.3 INCINERATION EMISSIONS
As with fuel-burning installations, the proper design of incinerators has been the subject of a great deal of
study. It is not appropriate to deal with this complex subject in detail in this document. The publication,
Interim Guide of Good Practice for Incineration at Federal Facilities,^ provides guidance as to good
design practice. It must be emphasized again that although theoretical considerations indicate any design
technique that will improve combustion will reduce emissions of POM, no quantitative information has
been found to show the actual reduction to be expected by good combustion as now conventionally
defined.
In view of the heterogeneous nature of refuse and the often erratic feed rates, good operation is of the
utmost importance in ensuring good combustion. At present, there appear to be no automatic control
systems that can fully control all the important variables of an incinerator—grate speed, over-fire air,
under-fire air, and furnace draft-to avoid smoky operation. Almost always the skill and vigilance of the
operating crew must be relied upon. For example, if the crane operator mixes various kinds of refuse in the
bin to give a furnace feed reasonably uniform in calorific value and moisture content, then it will be much
easier for the furnace operators to maintain good combustion.
The use of conventional gas-cleaning equipment to remove POM from incinerator effluent streams may be
considered along the general lines discussed for fuel-burning equipment. As in that case, removal of
particulates and incineration of organic vapors by conventional gas-cleaning techniques will reduce POM
emissions. However, conventional criteria for selection and design of gas-cleaning equipment for incinerators
are not exactly the same as for fuel-burning equipment because incinerator effluent streams are subject to
wide fluctuations in flow-rate, temperature, physical and chemical composition, and corrosive properties.
8.4 OPEN-BURNING EMISSIONS
Vegetation such as forest debris, crop residues, scrub, brush, weeds, and grass are burned in controlled fires
to:
• Control vegetation, insects, and other organisms harmful to desired plant life.
• Reduce waste volume.
• Improve land.
• Minimize fire hazards.
The emissions from open burning cannot be controlled directly. It has been found that burning agricultural
wastes in single-chamber incinerators without employing special emission control techniques and equipment
will not significantly reduce emissions of POM below that for open burning.
Other alternatives to incineration are to abandon or bury the materials at the site, to dispose of them in
remote areas, or to use them.
Coal refuse is piled near mining operations and coal cleaning and preparation plants. It typically consists of
less than 25 percent combustible matter. The principal materials in coal refuse are coal, slate, shale, bone,
calcite, gypsum, clay, pyrite, or marcasite. These culm piles are more likely to ignite if they contain
extraneous organic material such as wood or garbage. Camp fires or brush fires often furnish the ignition.
Spontaneous firing occurs by slow oxidation of the coal. Water may contribute to ignition by the heat of
wetting, depending on the physical nature of the coal and on humidity and precipitation.
Extinguishing or preventing such fires are the techniques used to eliminate emissions from coal refuse fires.
These methods involve locating the piles away from brush and other sources of ignition, cooling and
Control Technology 8-3
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repiling the refuse, sealing refuse with impervious material, injecting slurries of noncombustibles into the
refuse, minimizing the quantity of combustiles in the refuse, and extinguishing fires by such techniques as
digging them out.
8.5 INDUSTRIAL PROCESS EMISSIONS
There have been a very limited number of studies on emissions of POM or individual compounds such as
BaP from industrial processes. In addition to the problems of sampling and analysis common to all sources
of POM, industrial processes tend to be highly variable, making representative sampling difficult and
increasing the error of extrapolation to other sources even in the same industrial category. Also, for many
important processes such as coke production and roofing operations, pollutants are not discharged from a
definable point or stack but occur sporadically and from diffuse surfaces. Two general situations have the
most potential for emission of POM. Processes that involve incomplete combustion of carbonaceous
material may produce large quantities of POM. In the handling, processing, and utilization of aromatic
compounds, a common raw material in the chemical and light metal industries, POM may also be formed
and released.
The most important process emissions result because coal can contain significant quantities of POM. Some
is released when coal is heated as in the manufacture of coke, and much POM remains in the coal chemicals.
POM may be released in subsequent heating and use of other coking by-products such as coal tar pitch or
carbon electrodes in aluminum plants. The other industrial operations of potential importance are the
partial combustion of carbon such as in catalyst regeneration, or quenching operations used in the
manufacture of carbon black.
From the wide range of potential sources of POM, the following industrial processes seem most important
based on the available test data: petroleum refineries, coke ovens, use of coal-tar pitch, and asphalt
hot-road-mix manufacture.
8.5.1 Refinery Emissions
Although nearly every process and piece of equipment in a refinery can emit hydrocarbons, only those that
handle or process the heavy fractions at elevated temperatures will be significant emitters of POM.
Typical refinery processes likely to emit POM include: catalytic cracking and catalyst regeneration,
air-blowing of asphalt or other heavy oils, waste gas disposal system, oil-water effluent system, and boilers
and process heaters.
Boilers and process heaters are simply combustion operations, not unique to refineries, and were covered in
the section on stationary combustion sources. Of the remaining sources, only catalytic regeneration and
air-blowing have been tested specifically for POM emissions. The others must be considered potential, but
as yet unproven, emission sources.
POM is produced in the catalyst bed and in the regeneration system, in both the fluid- and moving-bed
systems. The regenerators can be considered inefficient combustion systems utilizing petroleum coke as a
fuel. The emissions will be a function of a variety of design and operational factors, including type of
feedstock, temperature, excess air available, throughput time, and type of afterburner used.
8.5.2 Coke Oven Emissions
Control of particulates from coking-through modified charging or pushing or through continuous
coking-are being investigated. The efficiency of POM control is a part of those studies. Since, however,
particulate emissions are expected to be reduced by 90 percent by particulate air standards, it is anticipated
mat POM will also be significantly reduced.
8-4 PARTICULATE POLYCYCLIC ORGANIC MATTER
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8.5.3 By-Product Plant Emissions
A study of a coal tar pitch plant has resulted in some specific recommendations for controlling gas and
steam emissions. The major sources of emissions were leaks in the equipment and the venting of waste gases
into the atmosphere through a washer sprayed with liquor from the gas-cooling cycle. Burning the waste
gases in a special afterburner failed because it was difficult to provide a sufficiently large contact surface
area at the 1,250 to 1,350°C temperatures required to decompose POM.
The first source of emissions, leaks in the equipment, was controlled by installing airtight doors. The second
source, the waste gas outlet, was controlled by venting the waste gases into the gas pipe for raw coal tar
pitch. These gases were then either collected in special apparatus or burned in furnaces at elevated
temperatures after mixing with coke-oven gases. The pitch preparation flow sheet was greatly simplified by
excluding the afterburner, trap, air washers, fans, and pump. The liquor from the gas washer cycle was no
longer needed, and its removal improved the cooling and washing of the coke-oven gas.
There are no sources of information on emission control techniques specifically for POM from coal tar
pitch at point of use.
8.5.4 Emissions from Hot Asphalt Batching and Airblowing
Hot asphalt batching plants are potential sources of heavy participate emissions, and for this reason have
been subject to control procedures. Cyclones, scrubbers, and bag filters have all been used.
On the basis of the theoretical considerations, the gas-cleaning equipment installed for particulate removal
should be effective in reducing POM emissions, although a higher degree of performance may be required to
reduce them to acceptable levels.
Airblowing of asphalts generates oil and tar mists and malodorous gaseous pollutants. It is common practice
to scrub the oils and tars from the hot (150 to 200° C) gas stream. Sea water is sometimes used for this
purpose. In any case, separators are necessary to reclaim the oil and prevent contamination of effluent
water. Afterburners are used to incinerate the uncondensed gases and vapors, which are odorous.
8.6 MOBILE SOURCES
8.6.1 Mechanism of POM Emission
Detailed evidence is lacking for a single, dominant reaction mechanism for the formation of POM in
combustion systems. Nevertheless, it has long been recognized that their formation in rich flames parallels
carbon formation.2 Thus, a wide variety of POM can be formed in sooting flames when C2-CS
hydrocarbons are used as fuels3 There is strong evidence that soot forms in flames through polymerization
(or oligomerization) of C2H fragments in the post-flame gases, with subsequent cross-linking of
polyacetylene chains.4 It seems likely that POM is formed in a similar way.2
Soot (and probably POM as well) persist in postflame gases from rich flames because of a deficiency of OH
radicals, a necessary reactant for the principal carbon burnout mechanism.5 Alkaline earth oxides are
known to suppress carbon formation; their principal mode of action has recently been shown to be catalysis
of OH radical formation.6 Thus, POM formation may well be tied to these features of carbon formation,
and POM emission may be influenced by local fuel-air ratio in the combustion zone, by persistence of OH
radicals in the postflame gases, and by the use of smoke suppressant additives.
Pyrolysis of oil or diesel fuel droplets could occur in locally oxygen-poor patches of combustion gas,
producing the case discussed in the NAS document. It is believed, however, that gas phase formation of
carbon dominates in real systems.5 Therefore, this mechanism cannot be ignored in discussion of POM
formation.
8.6.2 Control Technology for Mobile Sources
There are no elements of control hardware directed principally at POM emissions from mobile sources.
Most investigators seem to-feel that hydrocarbon control devices and engine modifications will also control
POM. Thus, decreasing fuel-air ratios in passenger cars has resulted in decreased POM emissions. Given the
Control Technology 8-5
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85 percent reduction figure in the NAS report, the relative importance of diesel emissions has increased
considerably.7 Thus, diesel- and gasoline-powered trucks must now be the leading mobile source of POM.
Opinions conflict on the potentiality for control of POM from cars by control of gasoline composition.
Thus, the work of Colucci and Begeman indicates a dramatic effect of lubricating oil consumption on BaP
emissions.8 By analogy, it might be expected that higher-molecular-weight hydrocarbons in the fuel might
increase POM emissions as well. Yet, recent work suggests that gasoline end-point or aromatics content have
minimal influences on POM.9 All these conclusions are now clouded by uncertainties in analytical results.
Thus, in recent studies it is believed that at least half the BaP and benz [a] anthracene were lost in the
sample-trapping procedure.9 It now appears important to develop a reliable, quick POM analytical
procedure and to resurvey prototype and in-use vehicles if the current and future picture of passenger car
POM emissions are to be reliably assessed.
Thus far, there has been very little work on diesels. The NAS report indicates correctly that the POM
emissions from diesels are a function of load.7 Whether variation in diesel fuel molecular weight, physical
properties, or use of carbon suppressant additives influence POM emissions is not known.
8.7 REFERENCES
1. Interium Guide of Good Practice for Incineration at Federal Facilities. National Air Pollution Control
Administration. Raleigh, N. C. Publication Number AP-46. 1969. 100 p.
2. Arthur, J. R., and D. H. Napier. Formation of Carbon and Related Materials in Diffusion Flames. In:
Proceedings of 5th Symposium on Combustion. Pittsburgh, 1955. p. 303-316.
3. Street, J. C!, and A. Thomas. Carbon Formation in Premixed Flames. Fuel. 34:4-36, 1955.
4. Homann, K. H. Soot Formation in Premixed Hydrocarbon Flames. Angew. Chem. Int. Ed. Engl.
7:414-427, 1968. ;
5. Fenimore, C. P., and G. W. Jones. Oxidation of Soot by Hydroxyl Radicals. J. Phys. Chem. 77:593-597,
1967.
6., Cotton, D. H., N. J. Friswell, and D. R, Jenkins. The Suppression of Soot Emission from Flames by
Metal Additives. Combustion and Flame. 77:87-98, 1971.
7. Particulate Polycyclic Organic Matter. National Academy of Sciences, Washington, D.C., 1972. 361 p.
8. Colucci, J., and C. R. Begeman. Society of Automotive Engineers. Paper Number 700469. 1970.
9. CRC-APRAC. Status Reports. Coordinating Research Council, Inc. New York. Quarterly Reports
1973.
8-6 PARTICULATE POLYCYCLIC ORGANIC MATTER
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APPENDIX
The information presented below became available as this report went to press; therefore, it is not
considered in discussions in this report but the reader should consider these data in evaluating annual
emissions.
Table A-1 ESTIMATED BEIMZO[a] PYRENE EMISSIONS
IN UNITED STATES, 1972a
Source Type
Emissions,
MT/yr
Stationary sources
Coal, hand-stoked and underfeed-stoked
residual furnaces
Coal, intermediate-size furnaces
Coal, steam power plants
Oil, residential through steam power type
Gas, residential through steam power type
Wood, home fireplaces
Enclosed incineration, apartment through
municipal type
Open burning, coal refuse
Open burning, vehicle disposal
Open burning, forest and agriculture
Open burning, other
Petroleum catalytic cracking
Coke production
Asphalt air-blowing
270
2
2
23
3
281
5
10
9
6
0.05 to 153
Mobile sources
Gasoline-powered, automobiles and trucks
Diesel-powered, trucks and buses
Rubber tire degradation
10
<1
10
From: Preferred Standards Path Report for Polycyclic Organic Matter. U.S. Environmental Protection Agency. Office of
Air Quality Planning and Standards. Durham, N.C. October 1974. p. 27-36.
A-1
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/6-75-001
3. RECIPIENT'S ACCESSION"NO.
4. TITLE AND SUBTITLE
Scientific and Technical Assessment Report on
Particulate Polycyclic Organic Matter
5. REPORT DATE
March 1975
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Research and Development
Special Studies Staff
Research Triangle Park, N.C. 27711
10. PROGRAM ELEMENT NO.
1AA001
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAM-E AND ADDRESS.
U.S. Environmental Protection Agency
Office of Research and Development
Office of Program Integration
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
repoft is a review and evaluation of the current knowledge of particu-
late polycyclic organic matter in the environment as related to possible deleterious
effects on human health and welfare. Sources, distribution, measurement, and control
technology are also considered. Results of an extensive literature search are
presented.
Experiments have shown a number of polycyclic organic compounds to be carcinogenic in
animals. Although these same compounds have not been proven to be carcinogenic in
humans, evidence strongly suggests that they may contribute to the "urban factor." In
American males, the urban lung cancer death rate is about twice the rural rate, even
after adjustment for differences in smoking habits. Evidence suggests significant
differences between specific urban areas across the United States.
The bulk of the available data is in terms of Benzo[a]pyrene? so this compound has
been used as an index on particulate polycyclic organic matter. Average seasonal
concentrations of BaP in the ambient atmosphere range from less than 1 ng/m^ in
nonurban areas to a maximum of 50 ng/m^ in rural areas.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDEDTERMS
c. COSATI Field/Group
Pollutant effects
Particulate polycyclic organic matter
Benzo[a]pyrene
Control technology
13. DISTRIBUTION STATEMEN1
Release Unlimited
19. SECURITY CLASS (This Report)
SbCUHl I Y CLASS (,
Unclassified
21. NO. OF PAGES
96
20. SECURITY CLASS (Thispage)
Unclassified
EPA Form 2220-1 (9-73)
B-l
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