United States
Environmental Protection
Agency
Health Effects Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S1-81-054 Sept. 1981
Project Summary
Respiratory Carcinogenicity of
Diesel Fuel Emissions
Alan M. Shefner
This program evaluated the possible
respiratory carcinogenic effects of
diesel fuel emission particles and
organic extracts of these particles in
suitable animal models. The Schreiber
method for localized tumor induction
was the model chosen to initiate this
study because of previous experience
in its use and its observed rapid
response time with certain known
direct acting carcinogens. Subse-
quently, studies were to be initiated
using the Saffiotti technique for intra-
tracheal instillation for evaluation of
life-time effects.
The program was initially planned
for a three-year period with the major
emphasis during the first year to be
placed on short-term studies with the
Schreiber model. Shortly after pro-
gram initiation a scientific review
meeting was held on the Diesel Emis-
sion Health Effects Research
Program. As a result of this meeting
and other program considerations
concerning risk assessment utility,
emphasis under this grant was gradu-
ally shifted to the utilization of the
Saffiotti intratracheal instillation
model. In addition, program plans
were modified to include the
assessment of coke oven extract,
roofing tar extract, and cigarette
smoke condensate on which a human
epidemiologic data base existed.
As a result of those considerations,
this grant was terminated after one
year and an extensive study utilizing
the Saffiotti technique was initiated
under EPA Grant No. R806929-01-0
on September 1, 1979.
This Project Summary was develop-
ed by EPA's Health Effects Research
Laboratory, Research Triangle Park.
NC, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction and Summary
This grant was initiated to provide
information relating to the potential
respiratory carcinogenicity of diesel
emission products. Emphasis was
placed on the Schreiber model for local-
ized tumor induction since it offered the
possibility of a more rapid deter mi nation
of adverse effects. Three initial experi-
ments were carried out using the
Schreiber technique in order to deter-
mine dose ranges of diesel extract
suitable for future experiments. A num-
ber of solvent mixtures including
dimethyl sulfoxide, propylene glycol,
ethanol and saline were investigated for
their ability to solubilize the extract at
desired concentrations.
Although it proved possible to prepare
and test extracts by this technique, it
was decided not to continue with
studies using this method of treatment
The localized treatment method cannot
be used with particle suspensions so no
direct comparison of the carcinogenic
potential of diesel fuel emission parti-
cles (DP) and diesel fuel emission
extract (DFE) can be carried out. In addi-
tion, this technique has not been widely
used and it has not been demonstrated
that the trachea is responsive to the
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classes of combustion products that are
present in DFE Furthermore, the total
dose of test material delivered to the
hamster cannot be readily determined
in this procedure. The concentration of
test material to which the test animals
are exposed is known, but how much of
the test material is retained by the
animal following the reabsorption
phase of the intubation cycle is uncer-
tain
Thus, it was concluded that while the
method is of potential interest as a
research tool, program emphasis was to
be placed on carcinogenicity trials using
the better established intratracheal
instillation method of Saffiotti.
An experiment was then carried out
to provide information for selection of
doses for the chronic study of diesel
particles by the Saffiotti method. Diesel
particles and DP-FeaOa mixtures were
prepared by bal.l milling. Hamsters were
treated at weekly doses of 1, 3, 5, and 10
mg. Animals at the 10 mg weekly level
were treated twice weekly with doses of
5 mg each. Hamsters were held for 5
weeks following the 15 weeks of treat-
ment, survivors were sacrificed, and
tissues were processed for histopatho-
logic examination. Twice weekly
treatments with 5 mg DP or with 5 mg
DP admixed with 5 mg of Fe203 led to a
decreased weight gain as compared to
control animals also receiving twice
weekly instillations.
Microscopic examination of histologic
sections of hamsters in this study
showed that a variety of lung lesions
occurred in treated animals that were
either absent in control hamsters or
present to a lesser extent. The degree of
severity and frequency of occurrence of
hyperplastic and metaplastic changes in
lung tissue of hamsters given twice
weekly treatments of 5 mg DP each plus
the decreased weight gain observed in
these treatment groups led to the con-
clusion that the high dose selected for
the chronic study would be 5 mg of
diesel particles, once weekly, for 15
weeks.
A limited study of lung clearance of
diesel particles was carried out on a
small group of hamsters. Each animal
was administered a single dose of 5 mg
DP by intratracheal instillation andpairs
of animals were killed at 1 hour, 8 days,
30 days and 60 days post treatment. The
lungs and trachea of one animal at each
time period were photographed and
lung and trachea from the second
animal were processed for histopatho-
logic examination.
Photographic reproductions of the
lungs and trachea of animals in this
study showed that the particles were
dispersed throughout the lung tissue as
well as the trachea at one hour post
instillation Eight days after the instilla-
tion the particles were still very
prevalent in the lungs, but appeared to
be mostly cleared from the trachea. At
30 days post instillation, the particles
remained heavily concentrated in the
lungs. Gross observation of a hamster
sacrificed 60 days post instillation
showed particles still remaining in the
lung but in apparently reduced
amounts.
The study demonstrated that the
Saffiotti method of intratracheal instil-
lation led to good dispersion of the
diesel particles throughout alveoli,
bronchioles, and bronchi. Although no
quantitative estimates of clearance
rates can be obtained, the photographic
representations and tissue sections
both showed that diesel particles were
still present in good number even 60
days after a single instillation of 5 mg of
DP.
Conclusions and
Recommendations
Following a presentation at a Diesel
Emission Health Effects Program
meeting in December of 1978 and sub-
sequent program discussions it was
decided to deemphasize work using the
Schreiber model and to initiate dose
range toxicity studies by the Saffiotti
intratracheal instillation technique.
This decision was reached for three
primary reasons.
1. The Saffiotti method offers a
proven and widely accepted model
for inhalation effects.
2. Total dose administered is known
with the Saffiotti technique but not
for the Schreiber method.
3. The Saffiotti method is ideal for the
evaluation of diesel emission par-
ticles which cannot be tested
using the Scheiber technique.
Since EPA's program for the evalua-
tion of the health effects of diesel fuel
emissions was aimed at developing a
series of potency comparisons between
diesel emissionsand other materialson
which there existed an epidemiologic
data base, itwasrecommendedthatthis
respiratory carcinogenesis study also
include an evaluation of these addi-
tional materials. Therefore, the
remainder of the first year of this grant
was devoted to initiating dose range
studies with diesel emission particles
using the Saffiotti method.
This grant was terminated after the
first year and the dose range studies I
were incorporated into and completed
under EPA Grant. No. R806929-01-0
which was entered into on September
1, 1979.
A/an M. Shefner is with 117Research Institute, Life Sciences Research Division.
10 West 35th Street, Chicago, IL 60616.
Donald E. Gardner is the EPA Project Officer (see below).
The complete report, entitled "Respiratory Carcinogenicity of Diesel Fuel
Emissions," (Order No. PB 81-230 955; Cost: $6.50, subject to change} will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Health Effects Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
US GOVERNMENT PRINTING OFFICE, 1981 757012'7356
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Environmental Protection
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Information
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