SERA
United States
Environmental Protection
Agency
Health Effects Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S1-81-009 Apr 1981
Project Summary
Investigation of Effects of
Prolonged Inhalation of
Nickel-Enriched Fly Ash in
Syrian Golden Hamsters
Alfred P. Wehner
Groups of 102 Male Syrian Golden
hamsters were chronically exposed to
~~70 /yg/l respirable Nickel Enriched
Fly Ash aerosol (high NEFA group),
—17 /jg/\ (low NEFA group), or —70
/jg/\ FA 6 hrs/day, 5 days/week for
up to 20 months. An identical control
group received sham exposures. The
NEFA particles of respirable size
contained approximately 6% nickel,
compared to about 0.3% for FA. Five
hamsters/group were sacrificed after
4,8,12, or 16 months of exposure. An
additional 5 hamsters/group were
withdrawn from exposure at the same
intervals for lifelong observations.
Exposures to NEFA had no
significant effect on the apparent
well-being, body weight and life span
of the animals although heavy
deposits of NEFA in the lungs were
demonstrated. The lung weights of
the high NEFA-and of the FA-exposed
animals, however, were significantly
(P<0.01) higher than those of low
NEFA controls. There was no
significant difference between the
mean body weights of the high NEFA
group and the FA group. The mean
'lung volumes were significantly
(P<0.01) larger for the high NEFA
group and the FA group than for the
low NEFA group and the controls.
There was a 100% incidence of dust
deposition, referred to in this report as
anthracosis, in the lungs of exposed
hamsters. Incidence and severity of
interstitial reaction and bronchioliza-
tion were significantly higher in the
dust-exposed groups than in the
sham-exposed controls. The severity
of anthracosis, interstitial reaction
and bronchiolization was significantly
lower (P<0.01) in the low NEFA group
than in the high NEFA and FA groups.
This dose-effect relationship reflects
the two different dose groups, namely
low NEFA versus high NEFA and FA.
While two malignant primary thorax
tumors were found in two hamsters of
the high NEFA group, no statistically
significant carcinogenesis was
observed. Of the exposure-related
changes, only anthracosis decreased
as a function of recovery time.
Comparison of pulmonary nickel
burdens after 20 months of exposure
with the aerosol concentration
suggests that the pulmonary
clearance rate was slower in the high
NEFA exposure group than in the low
NEFA exposure group.
The results of this study lead to the
conclusion that the addition of nickel
to fly ash under these experimental
conditions did not significantly
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(P<0.05) enhance the pathogenicity
(including carcinogenicity) of fly ash in
this animal model.
This Project Summary was
developed by EPA's Health Effects
Research Laboratory, Cincinnati, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information
at back).
Introduction
Clinical, epidemiological and
laboratory studies implicate nickel and
certain of its compounds as an
environmental health hazard. Exposure
of the general population to nickel
occurs mainly through the inhalation of
fly ash. Fly ash is a combustion product
of coal and fuel oil. It is discharged into
the atmosphere at an estimated rate of
several million metric tons per year in
the United States This quantity of fly
ash contains several thousand tons of
nickel. Because of its known toxicity
and presence in fly ash, it was desirable
to investigate whether nickel in fly ash
is an important etiological factor. This
was accomplished by enriching regular
fly ash with nickel and exposing
hamsters to nickel-enriched fly ash
(NEFA) or to regular fly ash (FA) and
comparing the findings to those in
sham-exposed controls. NEFA was
prepared by mixing nickel acetate into
pulverized coal before combustion in a
special fossil fuel furnace and collecting
the fly ash generated in the process.
A pulmonary deposition, transloca-
tion and clearance study with neutron-
activated fly ash to determine the fate of
the inhaled fly ash in the animals, and
an Ames assay to determine
mutagenicity complemented the
inhalation study.
Results and Conclusions
Exposure to NEFA had no significant
effect on the apparent well-being, body
weight and life span of the animals,
although heavy deposits of NEFA in the
lungs were demonstrated. The lung
weights of the high NEFA- and of the
FA-exposed animals, however, were
significantly (P<0.01) higher than those
of the low NEFA group and the controls.
There was no significant difference
between the MBWs of the high NEFA
group and the FA group. The mean lung
volumes were significantly (P<0.01)
larger for the high NEFA group and the
FA group than for the low NEFA group
and controls.
There was a 100% incidence of dust
deposition, referred to in this report as
anthracosis, in the lungs of exposed
hamsters. Incidence and severity of
interstitial reaction and bronchiolization
were significantly higher in the dust-
exposed groups than in the sham-
exposed controls. The severity of
anthracosis, interstitial reaction and
bronchiolization was significantly lower
(P<0.01) in the low NEFA group than in
the high NEFA and FA groups. This
dose-effect relationship reflects the two
different dose groups, namely low NEFA
versus high NEFA and FA. While two
malignant primary thorax tumors were
found in two hamsters of the high NEFA
group, no statistically significant
carcinogenesis was observed. Of the
exposure-related changes, only
anthracosis decreased as a function of
'recovery time.
Comparison of pulmonary nickel
burdens after 20 months of exposure
with the aerosol concentration suggests
that the pulmonary clearance rate was
slower in the high NEFA exposure group
than in the low NEFA exposure group.
The results of this study lead to the
conclusion that the addition of nickel to
fly ash under our experimental
conditions did not significantly (P<0.05)
enhance the pathogenicity (including
carcinogenicity) of fly ash in our animal
model.
The fly ash burden estimates from the
pulmonary deposition, translocation
and clearance experiment, as
determined by the radionuclides 46Sc
and 59Fe, are in good agreement for the
majority of samples analyzed. Such
close agreement indicates fly ash
paniculate levels in the lungs, carcass,
head, pelt, Gl tract, and feces rather
than leached radionuclides. Relative to
the 46Sc and the 59Fe-based estimates,
fly ash deposition estimates obtained
with the isotope 60Co were appreciably
lower for the lungs and appreciably
higher for one or more sacrifice times
for carcass, liver, head, pelt and urine
samples. This indicates that 60Co (and
thus the element cobalt) was selectively
leached from fly ash deposited in the
deep lung, translocated to other sites,
and excreted in the urine.
An estimated average of 63 /JQ fly ash,
or 2 to 3% of the inhaled fly ash, was
initially retained in the respiratory tract.
The estimated biological half-times of
the fly ash were 2.6 and 34.5 days,
probably for the airways and for the
deep lung, respectively. After 99 days,
the mean lung burden had decreased to
about 10% of its initial value. Estimated
near-complete clearance of fly ash from
the lung would have been achieved
approximately 200 days postexposure.
In all Ames assays the responses
were negative. Thus, NEFA and FA did
not appear to be mutagenic in the
standard Ames assay. However, this
does not preclude the possibility of
demonstrating mutagenic activity by
altering the standard Ames test in some
way or by use of different extraction
procedures to remove potential
mutagens from the surface of NEFA and
FA
Materials and Methods
Based on the results of acute and
subacute toxicity studies described in
this report, groups of 102 male Syrian
golden hamsters were chronically
exposed to —70/yg/l respirable NEFA
aerosol (high NEFA group), ~17//g/l
(low NEFA group), or ~70,ug/l FA 6
hrs/day, 5 days/week, for up to 23
months. An identical control group
received sham exposures. The NEFA
particles of respirable size contained
approximately 6% nickel, compared to
about 0.3% for FA. Five hamsters/group
were sacrificed after 4, 8, 12, or 16
months of exposure. An additional 5
hamsters/group were withdrawn from
exposure at the same intervals foi
observation until 22 months of ag€
when all animals were sacrificed.
To determine pulmonary deposition
translocation and clearance of inhalec
fly ash, hamsters received a single 95
minute nose-only exposure to neutron
activated fly ash. The mean respirable
aerosol concentration was 470 /ug/l
Over a period of 99 days postexposure
the hamsters were sacrificed in group:
of six animals. Lungs, liver, kidneys
decapitated and skinned carcass, pell
head, gastrointestinal tract, urine, ani
feces were collected for analysis of th
radionuclide tracers 46Sc, 69Fe, an
60Co, by x-ray spectrometry.
Dimethylsulfoxide (DMSO) extracts c
NEFA and FA were tested fc
mutagenicity in the postmitc
chondrial/'S3/rtW7e//a (AMES) assa
with and without metabolic activation
using Aroclor-induced hepatic enzyrri
preparations as the source of activatir
enzymes. The total concentration of F
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and NEFA in the DMSO solvent was
about 50 mg per ml. The concentrations
used in the Ames assays of NEFA and
FA ranged from 10 to 5000 /ug per petri
plate.
The final report submitted to the
Project Officer also included numerous
computer data sheets dealing with: list
of observations on individual animals,
list of animals with lesions; list of inci-
dence of lesions; and list of incidence by
type of tumor. This data is on file in the
Health Effects Research Laboratory,
26 W. St. Clair Street, Cincinnati, OH
45268.
Alfred P Wehner is with Battelle Pacific Northwest Laboratories, Richland, WA
99352.
Wellington Moore, Jr. and William E. Pepelko are the EPA Project Officers (see
below)
The complete report, entitled "Investigation of Effects of Prolonged Inhalation of
Nickel-Enriched Fly A sh in Syrian Golden Hamsters," (Order No PB81-152514;
Cost: $14.00, subject to change) will be available only from.
National Technical Information Service
5285 Port Royal Road
Springfield, V'A 22161
Telephone. 703-487-4650
The EPA Project Officers can be contacted at:
Health Effects Research Laboratory
U.S. Environmental Protection Agency
Cincinnati. OH 45268
i US GOVERNMENT PRINTING OFFICE 1981-757-012/7047
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300
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