EPA 560/5 -77-004
SAFETY OF
CHEMICAL SMOG SUPPRESSOR
FINAL TECHNICAL REPORT
August 1977
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF TOXIC SUBSTANCES
WASHINGTON, D.C 20460
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EPA 560/5 #-77-004
SAFETY OF CHEMICAL SMOG SUPPRESSORS
AUTHOR
Douglas L. Warf, NCSU
PREPARED BY
OFFICE OF TOXIC SUBSTANCES
ENVIRONMENTAL PROTECTION AGENCY
WANSHINGTON, D.C.
AUGUST 1977
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ABSTRACT
This paper describes information needed to evaluate the safety of chemicals
proposed as smog suppressors and means for obtaining this information.
Los Angeles and other large cities have frequent and severe smog conditions
that result from photochemical reactions on atmospheric pollutants.
Certain chemicals such as diethylhydroxylamine have been shown in the lab-
oratory to interfere with this photochemical process and should, if released at
the optimal time, place, and amount prior to or during smog conditions, signi-
ficantly reduce or eliminate smog. It has been further argued by those favoring
this approach to controlling smog that the cost of chemicals would be less than
the cost of fitting automobiles with catalytic converters now used to reduce
smog causing pollution.
It is agreed by all concerned that prior to any experimental use of these
chemicals that a thorough evaluation must be made of their safety. This refers
to long-term chronic effects to the environment or to persons likely to be
exposed and to acute effects from exposure from credible accidents in handling
and use of these chemicals.
The test protocols and the information obtained from models described in
this paper should provide adequate information needed to evaluate the safety of
these chemicals for the uses proposed.
Further information can be obtained by contacting Arthur M. Stern, Chemical
Testing Function, Office of Toxic Substances, Environmental Protection Agency.
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SAFETY OF CHEMICAL SMOG SUPPRESSORS
Introduction
Proposals have been made to use chemicals for delaying the formation of
photochemical smog. The scientific basis for this is their ability to react
with and remove the free hydroxyl radical that provides the essential link in
the photochemical smog chain reaction.
Diethyl hydroxylamine has been proposed by Heicklen as being particularly
useful in suppressing photochemical smog (1,3).
Questions pertaining to the merit and safety of using chemicals as smog
suppressors in urban environments have been raised by scientists in and out of
government. The purpose of this paper is to critically review these conflicting
claims and counter-claims for the benefits and risks of these proposed uses
for chemicals (2).
Any serious plans for employing chemicals as smog suppressors would require
evaluation of their advantages in terms of effectiveness, safety of use and
economics compared to the present approach for reduction of pollutants at their
emission source. The benefits to be derived by the source reduction of pollutants
from mobile and stationary emissions include abatement of photochemical smog and
alleviating other adverse effects from atmospheric pollutants. Adding another
chemical, however, to control photochemical smog will have no effect on lowering
the level of the hydrocarbons, nitrogen oxides, carbon monoxide, sulfur oxides
or any of the other pollutants in our urban atmospheres.
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It is not the purpose of this paper to assess the merits of various
alternative approaches to reducing the adverse effects of photochemical smog by
using chemicals but rather to suggest test protocols that, if adequately performed
should yield the data and information needed to evaluate their merits in terms
of effectiveness and safety.
Requirements for information outlined in this paper stem from proposals to
release quantities of smog-suppressing chemicals into the atmosphere of our major
cities where photochemical smog occurs. These urban areas have heterogenous
populations that can be assumed to represent a wide range of individual
sensitivities and responses to biologically active compounds present in the
environment. This becomes particularly important in view of recent estimates by
epidemiologists that up to 90% of the cancers reported in the U.S. are caused by
environmental factors.
Chemistry
The hydroxyl radical has been found to be the critical link in the formation
of photochemical smog. Several chemicals have the ability to scavenge off the
free hydroxyl radical. Among these are aniline, phenol, benzaldehyde,
naphthalene and diethyl hydroxylamine. All have an easily extractable hydrogen
with no hydrogen associated with the alpha-carbon atom. This hydrogen combines
with the hydroxyl radical to form water, thus inhibiting the photochemical re-
action and the formation of oxidants. If this delay is sufficiently long—then
it has been hypothesized that natural dispersive forces will dilute or remove
the pollutants and also reduce the sunlight hours available. This combined
effect provides a mechanism for preventing the oxidants formed in urban
atmosphere form reaching problem levels that originate primarily from auto
emissions (1,2,3).
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Unfortunately, this chemical approach to suppressing photochemical smog
will not reduce the level of hydrocarbons, nitrogen oxides or carbon monoxide
s*
in the urban atmosphere. If these pollutants are not reduced at the emission
source they will continue to further build-up the potential adverse effects.
Controlling precursors of photochemical smog at the emission source is
intended to provide more permanent benefits. Adding a chemical to those
already present in urban atmoshperes would at best have only a cosmetic effect
without reducing the total atmospheric pollutant load.
Proposed Techniques for Releasing Photochemical Smog Suppressors
Possible means for releasing suppressants to urban atmospheres are:
tEvaporation from elevated pots placed at intervals along heavily used
highways.
t Spraying chemicals vertically from moving automobiles.
• Spraying from aircraft, rockets, balloons.
There is a concern on the part of government scientists and others regarding the
effectiveness and safety of these chemicals when applied by these methods.
Means for dispensing chemicals need to be developed so they are uniformly
dispersed at an optimal rate and the concentration maintained over the entire
region to be treated during sunlight hours.
Perhaps the major logistics problem is in dispensing chemicals into the
polluted urban atmosphere instantly and uniformly. Non-uniform dispersion
presents several problems.
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In order to assure the presence of the requisite concentration of chemicals
to scavenge the free radicals, it would be necessary to use more chemicals than
theoretically needed to accomplish the objectives. Also, the concentrations at
the dispensing sites would, for a period of time, be much higher than the optimal
level needed at reaction sites with an attendant increase in the likelihood of
excessive exposure to motorists. Exposure of occupants in buildings down-wind
would be also a matter of concern.
In cities such as Los Angeles there may be up to 150 days per year that
could be treated with smog suppressing chemicals. If used this frequently the
possibility exists that these chemicals or their derivatives might deposit on
surfaces of vehicles, buildings or roads. There is also a potential run-off or
wash-off from soil and surfaces or from the atmosphere that could contaminate
streams and drinking water reservoirs. These problems are considered later in
this paper under Methods for Evaluating Effects - Aquatic Organisms.
The likelihood of one or more chemical plumes from the surface or elevated
dispensing pots combining to form a more concentrated plume or cloud should be
considered in evaluating safety. Inversions, downdrafts, wind, and precipitation
are micro-meterological factors that could result in the accumulation or
coalescing within the lower atmospheres or upon surfaces.
Possible spillage of chemicals during transport, filling or handling and
the consequences of resultant excessive environmental levels should also be
considered. Accidents between vehicles carrying or dispensing the potentially
hazardous chemicals and other unanticipated events, such as vandalism and
natural disasters, may also be problems.
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Spicer, et al,observed that certain free radical scavengers for inhibiting
photochemical smog reactions can cause large increases in light scattering
aerosols. They reported that this could result in a reduction of visibility
from 17 miles to 0.3 miles when 0.4 ppm aniline was released to the atmosphere
as an inhibitor. This type of information should be obtained in experimental
smog chambers for each chemical proposed (2).
The extent that the chemicals deplete the upper atmospheric ozone layer
with the attendant potential of short and long-term adverse health and climatic
effects should be evaluated.
Before any chemical is used in field experiments involving potential
environmental contamination a means for sampling and measuring its levels in
air, water, soil and crops should be available. A monitoring program should
be designed to obtain information on the current levels and trends of this
chemical which would permit a determination to be made of the build-up in the
environment and in the food chain.
An atmospheric dispersion model for chemicals need to be developed with
time, concentration and location (horizontal and vertical) as variables.
Parameters such as wind speed, inversions, downdrafts, and traffic density are
examples of other inputs that must be factored into a mathematical model.
Information and answers are needed on:
a) Time for effective release of chemicals
b) Places to release the chemicals
c) Amounts of chemicals to be release
d) Rate of release of chemicals
e) Time to discontinue release of the chemicals.
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The precision for determining each of the above parameters would affect
the amount of the chemical required to suppress smog. Since the inputs to,this
model change rapidly they must be available as needed.
The average large U.S. city has a rich supply of reactive pollutants in
its atmosphere. Any additional chemicals added must anticipate possible
atmospheric reactions between these atmospheric components and their effects.
These may include sulfur and nitrogen compounds and aldehydes.
To date there is no convincing evidence that the toxic and carcinogenic
diethylnitrosamines are formed in the polluted urban atmosphere in measureable
quantities(5). The addition of a chemical such as diethylhydroxylamine in
the quantities proposed would raise the possibility that diethylnitrosamines
could be formed (a chemical or metabolic derivative) at night. This compound
would be expected to decompose during sunlight hours, since it is photosensitive.
Photochemical reaction rates and products should be determined quantitatively
using a simulated polluted atmosphere with added chemical suppressors in an
experiment which exactly reproduces an atmospheric reaction that may occur in
an urban atmosphere. This should provide clues and indicators of physico-chemical
activity and other side effects(2).
Photochemical reactions also may occur on surfaces, such as, foliage, soil,
glass, and in water. Although of less concern than atmospheric reactions any
large scale use of a chemical would need to evaluate reaction products and the
ultimate fate and transport after being released uncontrolled into the urban
environment.
Toxicology of Photochemical Smog Suppressors
For chemicals that have a potential for mutagenic or carcinogenic activity
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serious questions exist as to whether it is possible to assign a safe threshold
exposure level. Evidence of mutagenic or carcinogenic activity observed in
animal experiments may restrict any potential environmental use, such as in
suppressing photochemical smog in populated urban environments(6).
In the following paragraphs the concerns expressed by government officials
and others regarding the potential short-term and delayed toxic manifestations
of chemicals released to populated areas are noted and the tests needed to make
an assessment of these questions are outlined with references to more complete
test protocols.
The feasibility or nonfeasibility of establishing a threshold, a tolerance
level or a no-effect level for a chemical released to the environment where there
is evidence of irreversible biological effects is presently under debate. Simi-
larily there are environmental health scientists who question whether benefits
should be weighed with risks in cases where the risks may involve adverse health
effects to a segment of the population that may be sensitive to low-level chronic
exposures(6).
Enormous resources would be required to assure that a chemical to be released
to the atmosphere or any of its reactants would not result in abrupt or long-term
effects to man or to the environment.
For a city with a large heterogeneous population such as Los Angeles it may
be assumed that a certain percentage of the peculation will be sensitive and
react adversely if exposed to a biologically active chemical. This sensitivity
may not be easily detectable. However, the skin patch test on humans could be
used to estimate the percentage of peculation sensitive to the epidermal exposure
of diethylhydroxylamine.
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Man's physiological make-up and his response to environmental stresses are
highly variable. The onset of abnormalities such as cancer, chronic lung
diseases, brain, kidney, and liver degeneration may be delayed or only be evident
through accelerated aging or later show up in inherited characteristics. Increasing
evidence indicates that environmental agents may be causitive factors for many
degenerative diseases.
Irreversible Biological Effects
The most critical information to evaluate is that concerning irreversible
adverse biological effects on humans. This refers primarily to mutagenesis,
carcinogenesis and teratogenesis. The various possible routes of exposure, i.e.,
inhalation, oral ingestion and skin absorption should be simulated and evaluated
in the laboratory.
Effects of acute, subacute and repeated low-level chronic exposures need
to be evaluated for the chemical and any of its derivatives that may be formed in the
urban environment.
The transport and fate of the chemical after discharging into the
atmosphere are important considerations in evaluating toxic effects. Methods for
measuring levels and trends in air, water and food must be known or developed.
This includes intermediates, metabolites and degradation products. Possible
synergistic effects from two or more atmospheric chemicals or other environmental
stress would be a factor in establishing a margin of safety in estimating safe
levels of exposure.
Indications that a chemical proposed for release in populated areas has been
demonstrated to be a carcinogen, mutagen or a teratogen in animals test would be
reason to remove it from further consideration. Where resources are limited
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for testing the toxic nature of this chemical and its derivatives, it would be
prudent to evaluate these chemicals in a manner that would be acceptable to
Federal, State, and local authorities responsible for approving safety and
efficency of use.
A battery of test methods have been developed by various laboratories for
evaluating the mutagenic, carcinogenic and teratogenic activity of a chemical.
References are provided for these protocols.
Methods for Evaluating Mutagenicity
There is evidence that chemicals known to be carcinogenic are also likely
to be mutagenic(7,8,9).
The primary objective of mutagen testing is to determine whether a chemical
has the potential of causing heritable alterations in the gene pool of man.
Where chemicals are released uncontrolled to the populated urban environments the
need to determine potential mutagenic activity becomes critical to the assessment
of its safety for use. Direct methods for this determination in man do not exist.
In recent years, a wide variety of in vitro mammalian systems have been developed
that do provide useful information for determinig whether a chemical has mutagenic
properties.
Test protocols for evaluating mutagenicity and carcinogenicity potential of
chemicals have been described by various laboratories and investigators.
A similar program is being developed to test the mutagenic activity of
pesticides by EPA, Office of Pesticide Programs in support of its Substitute
Chemical Program (2) iji vitro and i£ vivo procedures are being used by several
laboratories including the Litton Bionetics and Stanford Research Institute to
determine mutagenic potential of chemicals (1,16,20&21).
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The Litton Bionetic scheme describes a series of mutagenic assay procedures
for detecting mutagenic chemicals. This hierarchical or Tier Approach bioassays
chemicals in a stepwise fashion beginning with the most rapid and inexpensive
assays and continuing through the more time-consuming and costlier tests until
a definite assessment appropriate to the compound in question has been determined.
A chemical shown to have mutagenic properties in microorganisms would be eliminated
from further consideration. At this in vitro test phase of the evaluation the
costs in time and effort are relatively minor. Nonhierarchical approaches
utilize a matrix of rn_ vitro and ijr^ vivo tests all initiated simultaneously. The
purpose of this approach is to obtain a multifacted data-base on a chemical. This
is generally the recommended approach where only a single chemical is to be
evaluated and there is a need for extensive test data in a short time frame. The
matrix approach consists of two to five assays (1). A list of references includes
contributions from scientists and laboratories in evaluating chemicals for their
mutagenic characteristic are given in literature cited(7-21).
Methods for Evaluating Carcinogenicity
Man-made chemicals released to the environment make up part of the
environmental agents believed to cause up to 90 percent of the cancers being
reported in the U.S. The role of chemicals as a causitive agent in carcinogenesis
is receiving increasing emphasis in the scientific community and Federal agencies,
the National Institutes of Health (NCI), EPA and FDA.
In vivo animal bioassays are the only strigent proof of neoplastic activity
of a chemical. This approach to evaluating carcinogenesis is expensive and may
take 2 or 3 years of chronic exposures to obtain the information needed.
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Considerable progress has been reported in recent years in developing rapid
in vitro assays that are useful in predicting the potential of a chemical to
initiate cancers in humans.
In vitro mutagenicity assays using microbial indicator cells coupled with
mammalian microsomal activation system, (7,16,20) and in vitro malignant trans-
formation assays using rodent cells (24,25,26) appear to meet the requirements
of EPA in evaluating chemicals for carcinogenic potential.
A third series of assays using measures for the induction of unscheduled
DNA synthesis in cultured humans cells, also correlates with known carcinogens
(25,26).
Methods for Study of Reproductive and Teratogenic Toxicity
Of the principle irreversible biological diseases; cancer, mutants and
teratomas, the latter concerning reproductive abnormalities is generally of
lower priority when dealing with large populations for this proposed use of
a chemical. The placental barrier, metabolism and diluting factors reduce the
hazards to the developing embryo. The sensitivity of the embryo in various
stages of development to toxic substances is also a factor that must be considered.
The previous tests described for mutagenesis and carcinogenesis would, if positive,
strongly suggest that the compound is also a teratogen.
Although of less priority in the evaluation scheme it would be essential to
know whether a chemical had any effects on the reproductive systems of mammals
if a decision was made for its large scale use to suppress photochemical smog
in our large cities.
Teratologic studies have shown that the rat and mouse provides more consistent
and reliable data than the rabbit or hamster. It should be noted, however,
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that interspecies variation, in response to chemical dose and the difficulty of
finding any correlation with human experience raises doubt as to the significance
of teratologic tests(28,29).
The following references cover basic principles and procedure employed.
They also include detailed protocols recommended for regulatory purposes by the
FDA and the World Health Organization(29,30). Protocols for testing carcinogenic
activity of chemicals are described in the literature cited(22-31). Test
protocols for evaluating reproductive and teratogenic toxicity of one described
in references(19-20).
Methods for Study of Inhalation Toxicity
Accidents involving processing, transport, storage, filling, or disposal
of a chemical may result in acute levels in the breathing atmosphere of workers,
motorists or others in close proximity. Also high levels may result close to
a source of discharge of a chemical through evaporation or spraying from ground
base sources or aircraft.
Airborne chemicals may be inhaled in either the vapor phase or as an
aerosol, i.e., dust or mist. Studies designed to evaluate the potential hazard
to humans must, therefore, relate to the nature of the physico-chemical forms
in which the chemical exists and may be inhaled into the lungs.
Inhalation exposure is often a more difficult experimental procedure than
administration by any other route. Since exposure of animals via the inhalation
route is a specialized area, scientists experienced the use of inhalation chambers,
vapor and aerosol dispersion, should be consulted(32-36).
Inhalation, as a route of entry, results in the potential for toxic effects at
the site of entry, i.e., the lungs, as well as the same systemic toxic effects that
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may occur from entry of the chemical into the body via other routes. Changes
in pulmonary function may be the most sensitive measurement of effect when the
chemical has its primary action on the lung itself. Systemic effects of a
chemical including carcinogenic, mutagenic and teratogenic are measured by the
same techniques utilized in studies with oral administration.
Acceptable protocols and methods for evaluating the effects, if any, of
diethyl hydroxylamine and any other suppressor when inhaled are listed in
references(32-36).
Methods of Evaluating Skin and Eye Toxicity
The accidental exposure to diethylhydroxylamine during processing, storage,
transport, disposal or during the handling and use of a chemical for suppressing
photochemical smog could result in an acute or subacute exposure to the skin
or eyes.
Percutaneous absorption may be similar to oral ingestion or inhalation.
Such contacts may also result in dermatitis from exposure to the primary
irritant or delayed hypersensitivity. Several protocols for the study of acute
and chronic percutaneous absorption and irritation type are available for use
with a limited number of animal species. The human patch tests are available
to determine the potential for skin sensitization chemical and to screen those
susceptable to low level exposure. These tests should be conducted by a
physician,and legal, ethical and medical aspects considered. Such tests may
cause sensitization to a chemical. Acute exposures to potentailly hazardous
chemicals are generally accidental. Subacute could result from exposures during
spraying of the chemical from vehicles or evaporation from pots placed alongside
a heavily travelled highway.
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Acute eye contact studies can be made following one of several protocols;
most employ the rabbit as the test animal. Acceptable protocols for evaluating
toxic effects are described in the listed references (37-41).
Methods for Evaluating Effects on Aquatic Organisms
With over one-third of the days in Los Angeles having annoying levels of
photochemical smog the repeated use of chemicals could result in an accumulation
on roads, soil and buildings. Photochemical degradation and reactions with
other chemical components in the atmosphere, i.e., SO^, NO-, etc.,could also
result in the accumulation and run-off of the chemicals and their reaction
products into aquatic systems. Contamination of drinking water, fish and shell-
fish is also possible.
Estimates of amounts of chemicals that through run-off, fall-out, and
ultimately reaching water resources should be evaluated. A transoort model
based on information available on the movement, reaction rates, fall-out rates,
soil absorption and run-off must be developed.
Toxicity studies should include acute tests to determine the concentration
in water which causes a defined effect on 50 percent of an exposed aquatic
population in some short interval of time, typically, 48 to 96 hours. Chronic
toxicity tests should include exposure to levels of an order of magnitude less
than that where effects are observed in the acute exposure tests. These exposures
involve the presence of the chemical over the life cycle of the organisms. This
is from one stage in the life cycle to the same stage in the next generation.
Various parameters, including survival growth rate, locomotor activity, behavioral
changes, metabolities and reproductive effects should be observed, analysed and
measured.
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Toxicology studies in the aquatic environment are essential before full
scale use of a chemical smog suppressor is undertaken. Several varieties
organisms should be studied, i.e., daphnids, fish and shellfish, for potential
toxic effects.
Laboratory studies using synthetic sea water and fresh water are described
along with protocols for testing aquatic organisms in a synthetic or real marine
and fresh water environments.
It should be possible to design a laboratory testing program providing
information needed to evaluate the toxicity of a chemical to aquatic organisms
that can be completed in one year or less.
Unfortunately, extrapolation from laboratory to field situations is not
always easy. Organisms in the field are often subject to multiple environmental
stresses that may involve synergistic effects. Open water sources, streams,
reservoirs and coastal waters are subject to receiving run-off, rain-out, and
fall-out of chemicals, both natural and man-caused.
It would be difficult to design a field study that would provide meaningful
information on the effect of a chemical used as a smog suppressor upon a community
of aquatic organisms, however,it is recommended that field tests of aquatic systems
be conducted when laboratory tests made under controlled conditions indicate the
need. This need could result from a finding of significant toxic effects at
plausible environmental levels that could be predicted if the chemical is released
into the environment in the manner proposed.
Protocols are available describing laboratory and field testing of the
effects of chemical on aquatic organisms(42-47).
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Contamination of Crops, Food and feed_
The proposed use of a chemical for suppressing photochemical smog is a
potential source of contamination of edible crops that are used as food for
humans and feed for domestic animals. Contamination of crops and feed stored in
open fields for domestic animals would be a likely source of contamination.
Produce from gardens, orchards and farms including leafy vegetable and fruit
could be contaminated as the result of discharges of chemicals to the atmosphere
Concern usually would be with the repetitive chronic dosage to humans from con-
sumption of food and feed that are consumed daily or periodically.
Contamination of foods such as lettuce, cabbage and broccoli should be
considered in food exposure pathways directly to humans, while hay, oats, and
grazing grass would be of concern through possible contamination of meat and
milk-producing domestic animals. Added to this exposure would be possible
contamination of drinking water.
Photochemical reactions of nitric oxide and nitrogen dioxide with unsat-
uarated hydrocarbons can produce phytotoxic peroxyacetyl nitrate (PAN).
Ethylene, olefins, and aromatic compounds are precursors of PAN. The use of
diethylhydroxylamine yields alcohol, as a photochemical product in a postulated
atmospheric reaction. Ethylene, one of the procusors of PAN, is a likely
intermediate. This possibility should be examined in experimental smog chambers
(48).
Ethylene has been found to be toxic to vegetation. The demise of the cut-
flower industry in Los Angeles and San Francisco was due, at least in part, to
ethylene(49).
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
FPA
R-77-nru
3. RECIPIENT'S ACCESSI Of* NO.
4. TITLE AND SUBTITLE
Safety of Chemical Smog Suppressors
5. REPORT DATE
August 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO
Douglas L. Warf, NCSU
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
University Coordinator for Environmental Studies
145 Harrelson Hall; Box 5971
Raleigh, N.C. 27607
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Toxic Substances
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Final Technical Report
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This paper describes information needed to evaluate the safety of chemicals
proposed as smog suppressors and means for obtaining this information.
Los Angeles and other large cities have frequent and severe smog conditions that
result from photochemical reactions on atmospheric pollutants.
Certain chemicals such as diethylhydroxylamine have been shown in the laboratory
to interfere with this photochemical process and should, if released at the optimal
time, place, and amount prior to or during smog conditions, significantly reduce or
eliminate smog. It has been further argued by those favoring this approach to control-
ling smog that the cost of chemicals would be less than the cost of fitting automobiles
with catalytic converters now used to reduce smog causing pollution.
It is agreed by all concerned that prior to any experimental use of these chemical
that a thorough evaluation must be made of their safety. This refers to long-term
chronic effects to the environment or to persons likely to be exposed and to acute
effects from exposure from credible accidents in handling and use of these chemicals.
The test protocols and the information obtained from models described in this
paper should provide adequate information needed to evaluate the safety of these
chemicals for the uses proposed.
KEY WORDS AND DOCUMENT ANALYSIS .
DESCRIPTORS
IvIDF-NTIFIERS/OPEN ENDFH TE^MS C COSATI I
air pollution biological effects
carcinogenicity dermal toxicity
environmental effects inhalation
nutagenicity ophtlialmic toxicity
photochemical reproductive effects
mog teratogenetic effects
toxicology
&. QlL inlliuTlONI STATEMENT
Unlimited
19. Sf PURITY CLASS (This l
21 NO OF
,f_i ed_ .
20 SE-CvjRiTY Cl ASS (Tlii* page)
Unclassified
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