United States
Environmental Protection
Agency
Office of Water
Regulations and Standards
Criteria and Standards Division
Washington DC 20460
EPA 440/5-80-017
October 1980
Water Quality
Criteria for
Acrylonitrile
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AMBIENT WATER QUALITY CRITERIA FOR
ACRYLONITRILE
Prepared By
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Water Regulations and Standards
Criteria and Standards Division
Washington, D.C.
Office of Research and Development
Environmental Criteria and Assessment Office
Cincinnati, Ohio
Carcinogen Assessment Group
Washington, D.C.
Environmental Research Laboratories
Corvalis, Oregon
Duluth, Minnesota
Gulf Breeze, Florida
Narragansett, Rhode Island
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DISCLAIMER
This report has been reviewed by the Environmental Criteria and
Assessment Office, U.S. Environmental Protection Agency, and approved
for publication. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
AVAILABILITY NOTICE
This document is available to the public through the National
Technical Information Service, (NTIS), Springfield, Virginia 22161.
11
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FOREWORD
Section 304 (a)(l) of the Clean Water Act of 1977 (P.L. 95-217),
requires the Administrator of the Environmental Protection Agency to
publish criteria for water quality accurately reflecting the latest
scientific knowledge on the kind and extent of all identifiable effects
on health and welfare which may be expected from the presence of
pollutants in any body of water, including ground water. Proposed water
quality criteria for the 65 toxic pollutants listed under section 307
(a)(l) of the Clean Water Act were developed and a notice of their
availability was published for public comment on March 15, 1979 (44 FR
15926), July 25, 1979 (44 FR 43660), and October 1, 1979 (44 FR 56628).
This document is a revision of those proposed criteria based upon a
consideration of comments received from other Federal Agencies, State
agencies, special interest groups, and individual scientists. The
criteria contained in this document replace any previously published EPA
criteria for the 65 pollutants. This criterion document is also
published in satisifaction of paragraph 11 of the Settlement Agreement
in Natural Resources Defense Council, et. alI. vs. Train, 8 ERC 2120
(D.D.C. 1976), modified, 12 ERC 1833 (D.D.C. 1979).
The term "water quality criteria" is used in two sections of the
Clean Water Act, section 304 (a)(l) and section 303 (c)(2). The term has
a different program impact in each section. In section 304, the term
represents a non-regulatory, scientific assessment of ecological ef-
fects. The criteria presented in this publication are such scientific
assessments. Such water quality criteria associated with specific
stream uses when adopted as State water quality standards under section
303 become enforceable maximum acceptable levels of a pollutant in
ambient waters. The water quality criteria adopted in the State water
quality standards could have the same numerical limits as the criteria
developed under section 304. However, in many situations States may want
to adjust water quality criteria developed under section 304 to reflect
local environmental conditions and human exposure patterns before
incorporation into water quality standards. It is not until their
adoption as part of the State water quality standards that the criteria
become regulatory.
Guidelines to assist the States in the modification of criteria
presented in this document, in the development of water quality
standards, and in other water-related programs of this Agency, are being
developed by EPA.
STEVEN SCHATZOW
Deputy Assistant Administrator
Office of Water Regulations and Standards
111
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ACKNOWLEDGEMENTS
Aquatic Life Toxicology:
William A. Brungs, ERL-Narragansett
U.S. Environmental Protection Agency
David 0. Hansen, ERL-Qulf Breeze
U.S. Environmental Protection Agency
Mammalian Toxicology and Human Health Effect;:
Ahmed E. Ahmed (author)
University of Texas Medical Branch
Norman Trieff (author)
University of Texas Medical Branch
Terence M. Grady (doc. mgr.) ECAO-Cin
U.S. Environmental Protection Agency
Jerry F. Stara (doc. mgr.) ECAO-Cin
U.S. Environmental Protection Agency
Carl Gabriel
Medical College of Pennsylvania
Rolf Hartung
University of Michigan
Pat Hilgard, OTS
U.S. Environmental Protection Agency
Chandler Mehta
University of Texas
Cynthia Robinson
National Institute for Occupational
Safety and Health
Roy E. Albert*
Carcinogen Assessment Group
U.S. Environmental Protection Agency
J.P. Bercz, HERL
U.S. Environmental Protection Agency
Patrick Durkin
Syracuse Research Corporation
L. Fishbein
National Center for Toxicological
Research
Thomas Haley
National Center for Toxicclogical
Research
Steve Kedtke, ERL-Duluth
U.S. Environmental Protection Agency
Charles Hiremath, CAG
U.S. Environmental Protection Agency
Jean C. Parker, ECAO-RTP
U.S. Environmental Protection Agency
Carl C. Smith
University of Cincinnati
Technical Support Services Staff: D.J. Reisman, M.A. Garlough, B.L. Zwayer,
P.A. Daunt, K.S. Edwards, T.A. Scandura, A.T. Pressley, C.A. Cooper.
M.M. Denessen.
Clerical Staff: C.A. Haynes, S.J. Faehr, L.A. Wade, D. Jones, B.J. Bordicks,
B.J. Quesnell, P. Gray, R". Rubinstein.
*CAG Participating Members: Elizabeth L. Anderson, Larry Anderson, Dolp'n Arnicar,
Steven Bayard, David L. Bayliss, Chao W. Chen, John R. Fowle III. Bernard Haberman
Charalingayya Hiremath, Cnang S. Lao, Robert McGaughy, Jeffrey Rosenblatt,
Dharm V. Singh, and Todd W. Thorslund.
iv
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TABLE OF CONTENTS
Criteria Summary
Introduction A-l
Introduction B-l
Effects B-l
Acute Toxicity B-l
Chronic Toxicity B-2
Plant Effects B-2
Residues B-2
Miscellaneous B-2
Summary B-3
Criteria B-4
References B-9
Mammalian Toxicology and Human Health Effects C-l
Introduction C-l
Exposure C-7
Ingestion from Water C-7
Ingestion from Food C-ll
Inhalation C-13
Dermal C-17
Pharmacokinetics C-18
Absorption and Distribution C-18
Metabolism C-20
Excretion C-28
Effects C-28
Acute, Subacute, and Chronic Toxicity C-28
Synergism and/or Antagonism C-45
Teratogenicity C-47
Mutagenicity C-58
Carcinogenicity C-61
Criterion Formulation C-100
Existing Guidelines and Standards C-100
Current Levels of Exposure C-102
Special Groups at Risk C-104
Basis and Derivation of Criterion C-104
References C-107
Appendix C-132
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CRITERIA DOCUMENT
ACRYLONITRILE
CRITERIA
Aquatic Life
The available data for acrylonitrile indicate that acute toxicity to
freshwater aquatic life occurs at concentrations as low as 7,550 ug/1 and
would occur at lower concentrations among species that are more sensitive
than those tested. No definitive data are available concerning the chronic
toxicity of acrylonitrile to sensitive freshwater aquatic life but mortality
occurs at concentrations as low as 2,600 ug/1 with a fish species exposed
for 30 days.
Only one saltwater species has been tested with acrylonitrile and no
statement can be made concerning acute or chronic toxicity.
Human Health
For the maximum protection of human health from the potential carcino-
genic effects due to exposure of acrylonitrile through ingestion of contami-
nated water and contaminated aquatic organisms, the ambient water concentra-
tions should be zero based on the non-threshold assumption for this chemi-
cal. However, zero level may not be attainable at the present time. There-
fore, the levels which may result in incremental increase of cancer risk
over the lifetime are estimated at 10 , 10"6, and 10~7. The corres-
ponding recommended criteria are 0.58 ug/1, 0.058 ug/1, and 0.006 ug/1,
respectively. If the above estimates are made for consumption of aquatic
organisms only, excluding consumption of water, the levels are 6.5 ug/1,
0.65 ug/1, and 0.065 ug/1, respectively.
VI
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INTRODUCTION
Acrylonitri le is an explosive, flammable liquid having a normal boiling
point of 77°C and a vapor pressure of 80 torr (20°C). The toxic effects of
acrylonitrile are similar to cyanide poisoning although not identical. The
chemical structure of acrylonitrile, ChL = CHCN, resembles that of vinyl
chloride, a material known to cause human cancer.
At present 1.6 billion pounds of acrylonitrile per year are manufactured
in the United States. The major use of acrylonitrile is the manufacture of
copolymers for the production of acrylic and modacryclic fibers by copoly-
merization with methyl acrylate, methyl methacrylate, vinyl acetate, vinyl
chloride, or vinylidene chloride [National Institute for Occupational Safety
and Health (NIOSH), 1977]. Other major uses of acrylonitrile include the
manufacture of acrylonitrile-butadiene-styrene (ABS) and styrene-acryloni-
tn'le (SAN) resins (used to produce a variety of plastic products), nitrile
elastomers and latexes, and other chemicals (e.g., adiponitrile, acryla-
mide). Acrylonitrile has been used as a fumigant; however, all U.S. regis-
trations for this use were voluntarily withdrawn as of August 8, 1978 (43 FR
35099). The U.S. Food and Drug Administration has recently banned the use
of an acrylonitrile resin for soft drink bottles (Anonymous, 1977, 1978),
but its use is still allowed in other food packaging. NIOSH estimates that
125,000 persons are potentially exposed to acrylonitrile in the workplace
(NIOSH, 1977).
At present the body of evidence produced in both toxicity studies on
laboratory animals and occupational epidemiologic studies on man suggests
that acrylonitrile may be a human carcinogenic. Thus, NIOSH has recently
stated that "acrylonitrile must be handled in the workplace as a suspect hu-
man carcinogen" (NIOSH, 1978). This judgment of NIOSH is based primarily on
(1) a preliminary epidemiologic study of E.I. du Pont de Nemours and Co.,
A-l
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Inc. on acrylonitrile polymerization workers from one particular textile
fibers plant (Camden, S.C. ); in this study, it was ascertained that a sub-
stantial excess risk (twice that expected) of lung and colon cancers
occurred between 1969 and 1975 in a cohort exposed between 1950 and 1955
(O'Berg, 1979); (2) interim results from ongoing 2-year studies on labora-
tory rats performed by the Dow Chemical Co., and reported by the Manufactur-
ing Chemists Association (April, 1977) (43 FR 192 45764) in which, by either
drinking water (Quast, et al. 1980) or inhalation routes (Maltoni, et al.
1977) of acrylonitrile exposure, laboratory rats developed CNS tumors and
Zymbal's gland carcinomas, not evident in control animals.
Aside from suggestive evidence of carcinogenicity in man and the experi-
mental evidence in animals, numerous workers have reported on the other gen-
otoxic charactistics of acrylonitrile (embryotoxicity, mutagenicity, and
teratogenicity) in laboratory animals (Venitt, et al. 1977; Milvey and
Wolff, 1977; Murray, et al. 1976). Even though there is some controversy
over the chronic effects of acrylonitrile (Shaffer, 1975), the acute toxic-
ity of acrylonitrile is well known, and the compound appears to exert part
of its toxic effect through the release of inorganic cyanide (Fassett, 1963;
Wilson, 1944).
A-2
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REFERENCES
Anonymous. 1977. Chemical and Engineering News. Am. Chem. Soc.
Washington, D.C. Sept. 12, 1977.
Anonymous. 1978. Chemical and Engineering News. Am. Chem. Soc.
Washington, D.C. Jan. 23, 1978.
Fassett, D.W. 1963. Cyanides and Nitriles. ]!n: Industrial Hygiene and
Toxicology. Vol. II. Interscience Publishers, New York.
Maltoni, C., et al. 1977. Carcinogenicity bioassays on rats of acryloni-
trile administered by inhalation and by ingestion. Med. Lavoro. 68: 401.
Mi Ivy, P. and M. Wolff. 1977. Mutagenic studies with acrylonitrile.
Mutat. Res. 48: 271.
Murray, F.J., et al. 1976. Teratologic evaluation of acrylonitrile mono-
mer given to rats by gavage. Rep. Toxicol. Res. Lab. Dow Chemical Co.
Midland, Michigan.
National Institute for Occupational Safety and Health. 1977. Current In-
telligence Bulletin: Acrylonitrile. July 1. Dept. Health Edu. Welfare.
Rockville, Maryland.
A-3
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National Institute for Occupational Safety and Health. 1978. a recommended
standard for occupational exposure to acrylonitrile. DHEW Publ. No.
78-116. U.S. Gov. Printing Office. Washington, D.C.
O'Berg, M. 1979. Epidemiologic studies of workers exposed to acryloni-
ile; preliminary results. E.I. Dupont de Nemours & Co.
Ouast, J.F., et al. 1980. A two year toxicity and oncognicity study with
acrylonitrile incorporated in the drinking water of rats. Toxicol. Res.
Lab. Health Environ. Res. Dow Chemical Co.
Shaffer, C.B. 1975. Toxicology of Acrylonitrile. ln_: F.A. Ayer, (ed.),
Environmental Aspects of Chemical Use Rubber Process Operations. Conf. Proc.
Venitt, S., et al. 1977. Mutagenicity of acrylonitrile (cyanoethylane) in
Escherichia coli . Mutat. Res. 45: 283.
Wilson, R.H. 1944. Health hazards encountered in the manufacture of syn-
thetic rubber. Jour. Am. Med. Assoc. 124: 701.
A-4
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Aquatic Life Toxicology*
INTRODUCTION
Most of the toxicity data concerning the effects of acrylonitrile on
freshwater aauatic life has been determined using static test conditions
without measured concentrations. The 48-hour EC™ value for Daphnia magna
and the 96-hour LCcn values for three fish species range from 7,550 to
33,500 wg/1, indicating that the range of sensitivity among these species is
not great. However, it is not known whether other freshwater fish and in-
vertebrate species are more or less sensitive to acrylonitrile exposure.
Chronic lethal effects on one fish species were observed after 30 days with
an LC5Q value of 2,600 wg/1.
The only datum for saltwater organisms is a 24-hour IC™ for pinfish.
EFFECTS
Acute Toxicity
The only datum for freshwater invertebrate species is the 48-hour EC^Q
of 7,550 wg/1 for Daphnia magna (Table 1).
Three freshwater fish species representing three families have been
tested with acrylonitrile. In soft water static tests using unmeasured con-
centrations, the 96-hour LC50 values were 11,800 wg/1 for the bluegill,
18,100 wg/1 for the fathead minnow, and 33,500 wg/1 for the guppy (Table
1). In addition, Henderson, et al. (1961) measured the sensitivity of the
fathead minnow to acrylonitrile under different test conditions and water
auality. The 96-hour LCeQ value at a hardness of 380 mg/1 as CaCO., and
*The reader is referred to the Guidelines for Deriving Water Quality Cri-
teria for the Protection of Aauatic Life and Its Uses in order to better un-
derstand the following discussion and recommendation. The following tables
contain the appropriate data that were found in the literature, and at the
bottom of each table are calculations for deriving various measures of tox-
icity as described in the Guidelines.
8-1
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pH 8.2 was 14,300 ug/1 while that at a hardness of 20 mg/1 as CaC03 and pH
7.4 was 18,100 ug/1 (Table 1). Changes in water duality within the range
studied apparently did not affect the toxicity of acrylonitrile. Also,
flow-through and static test conditions were compared using unmeasured
concentrations, and the LCcg value for the fathead minnow was lower for
the flow-through test (10,100 ug/l) than for the static test (18,100 ug/1).
Chronic Toxicity
Daphnia magna has been exposed for its life cycle and the results indi-
cate no adverse effects at concentrations as high as 3,600 ug/1 (Table 2).
This concentration is only about one-half of the 48-hour EC5Q (7,550 ug/1)
for the same species under comparable conditions (U.S. EPA, 1978). This
small difference between acute and chronic effects for Daphnia magna is un-
like that relationship between acute and chronic effects for the fathead
minnow. Henderson, et al. (1961), using flow-through methods and unmeasured
concentrations, observed a 96-hour LCj-Q of 10,100 ug/1 (Table 1) and when
that test was continued the 30-day LC5Q was 2,600 ug/1 (Table 4).
Plant Effects
No freshwater or saltwater toxicity data are available for any plant
species.
Residues
The bluegill was exposed for 28 days to C-acrylonitrile with thin
layer chromatography being used to verify exposure and tissue concentrations
(U.S. EPA, 1978). The bioconcentration factor for whole body was 48 (Table
3) with a half-life in the tissues of between four and seven days.
Miscellaneous
As stated earlier, the 30-day LCcQ for fathead minnows under flow-
through conditions was 2,600 ug/1 (Table 4), a result that is about one-
fourth of the comparable 96-hour LC5Q of 10,100 ug/1. Intermediate LC5Q
B-2
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values were 6,900 ug/1 after 10 days and 4,200 ug/1 after 20 days. These
data suggest that mortality would continue to occur even after 30 days, fur-
ther depressing the LC^Q value. Henderson, et al. (1961) also exposed
adult bluegill to 5,000 ug/1 for 1 to 4 weeks and prepared the fish for a
taste study panel (Table 4). No flavor impairment was detected at that con-
centration, which was almost one-half of the 96-hour LCgQ value for the
bluegill as determined by the same investigators. It is therefore unlikely
that acrylonitrile will impair the flavor of freshwater fishes.
Summary
The data base for acrylonitrile is deficient in several important as-
pects. Acute toxicity data are lacking for planktonic or benthic crus-
taceans, benthic insects, detritivores, and salmonid fishes. Of the data
available, only one of the 96-hour LC,-n values for the fathead minnow was
generated in a flow-through test, the rest being static tests; all acute
tests used unmeasured concentrations. The ranoe of EC™ and LCcn values
is from 7,550 to 33,500 ug/1. The chronic data are limited to one inconclu-
sive test with Daphm'a magna and a 30-day LC5Q value for the fathead min-
now of 2,600 ug/1.
Despite these limitations, there is enough information available to in-
dicate that acrylonitrile merits some consideration of its possible toxico-
logical effects on freshwater aouatic life. In particular, these data sug-
gest that acrylonitrile has a definite chronic or cumulative effect and that
adverse effects can be expected to occur at concentrations below 2,600 ug/1
in fish exposed to this compound for more than 30 days.
The only datum on saltwater species is a 24-hour LC(-0 value of 24,500
ug/1 for the pinfish.
B-3
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CRITERIA
The available data for acrylonitrile indicate that acute toxicity to
freshwater aiuatic life occurs at concentrations as low as 7,550 yg/1 and
would occur at lower concentrations among species that are more sensitive
than those tested. No definitive data are available concerning the chronic
toxicity of acrylonitrile to sensitive freshwater aouatic life but mortality
occurs at concentrations as low as 2,600 ug/1 with a fish species exposed
for 30 days.
Only one saltwater species has been tested with acrylonitrile and no
statement can be made concerning acute or chronic toxicity.
3-4
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Table 1. Acute values for aery Ion ItrIle
LC50/EC50
Species Method* (ug/l)
Species Mean
Acute Value
(ug/l) Reference
FRESHWATER SPECIES
Cladoceran, S, U 7,550
Daphnla magna
Fathead minnow, S, U 14,300
Plmephales promelas
Fathead minnow, S, U 18,100
Plmephales promelas
Fathead minnow, FT, U 10,100
Plmephales promelas
Guppy, S, U 33,500
Poecilia reticulata
Bluegll 1, S, U 11,800
Lepomis macrochlrus
Bluegll 1, S, U 10,100
Lepomis macrochlrus
7,550 U.S. EPA, 1978
Henderson, et at.
1961
Henderson, et al.
1961
13,800 Henderson, et al.
1961
33,500 Henderson, et al.
1961
Henderson, et al.
1961
10,900 U.S. EPA, 1978
* S = static, FT = flow-through, U = unmeasured
No Final Acute Values are calculable since the minimum data base requirements are not met.
B-5
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Table 2. Chronic values for aerylonltrlle (U.S. EPA, 1978)
Species Mean
Limits Chronic Value
Method* (ug/l) (ug/1)
FRESHWATER SPECIES
Cladoceran, LC >3,600
Daphnla magna
• LC = life cycle or partial life cycle
No acute-chronic ratio Is calculable.
B-6
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Table 3. Residues for aerylonltrlla (U.S. EPA, 1978)
Bloconcentratlon Duration
Species Tissue Factor (days)
FRESHWATER SPECIES
Blueglll, whole body 48 28
LapproIs macrochlrus
B-7
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Table 4. Other data for scrylonltrlle
Species
Fathead minnow,
Plmephales promelas
Bluegi I I,
Lepomls macrochlrus
Bluegi11 (fIngerlIng),
Lepomls macrochlrus
Duration Effect
FRESHWATER SPECIES
30 days LC50
1-4 wks No detectable
flavor Impair-
ment of tissues
96 hrs lOOJf survival
Result
(ug/l)
2,600
5,000
10,000
Reference
Henderson, et a I.
1961
Henderson, et al.
1961
Buzzel, et al. 1968
Plnflsh,
Lagodon rhomboldes
24 hrs
SALTWATER SPECIES
LC50
24,500 Oaugherty & Garrett,
1951
B-8
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REFERENCES
Buzzell, J.C., et al. 1968. Behavior of organic chemicals in the aouatic
environment. Part II. Behavior in dilute systems. Manufacturing Chemists
Assoc., Washington, D.C.
Daugherty, P.M., Jr. and J.T. Garrett. 1951. Toxicity levels of hydrocy-
anic acid and some industrial by-products. Texas Jour. Sc. 3: 391.
Henderson, C., et al. 1961. The effect of some organic cyanides (nitriles)
on fish. Eng. Bull. Ext. Ser. Purdue Univ. No. 106. p. 130.
U.S. EPA. 1978. In-depth studies on health and environmental impacts of
selected water pollutants. U.S. Environ. Prot. Agency, Contract No.
68-01-4646.
B-9
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Mammalian Toxicology and Human Health Effects
INTRODUCTION
Acrylonitrile is an explosive, flammable liquid having a nor-
mal boiling point of 77°C and a vapor pressure of 80 torr (20°C).
The toxic effects of acrylonitrile are similar to cyanide poisoning
although not identical. The chemical structure of acrylonitrile,
CH2=CHCN, resembles that of vinyl chloride, a material known to
cause human cancer. Synonyms for acrylonitrile include cyanoethy-
lene, 2-propenenitrile, VCN, and vinyl cyanide. Polymerization
grade acrylonitrile contains a number of impurities and additives,
namely, dimethylformamide, hydrogen peroxide, hydroxyanisole,
methyl acrylate, phenyl ether-biphenyl mixture, sodium metabisul-
fite, sulfur dioxide, sulfuric acid, and titanium dioxide (O'Berg,
1977b).
At the present time, 1.6 billion pounds of acrylonitrile per
year are manufactured in the United States by the reaction of pro-
pylene with ammonia and oxygen in the presence of a catalyst. (A
number of other processes are used outside the United States.) Cur-
rent domestic producers of acrylonitrile are American Cyanamid Com-
pany (New Orleans, Louisiana), E. I. du Pont de Nemours Company,
Inc. (Beaumont, Texas and Memphis, Tennessee), Monsanto Company
(Chocolate Bayou, Texas), and The Standard Oil Company (Lima,
Ohio).
The major use of acrylonitrile is in the manufacture of
copolymers for the production of acrylic and modacrylic fibers by
copolymerization with methyl acrylate, methyl methacrylate, vinyl
acetate, vinyl chloride, or vinylidene chloride. Acrylic fibers,
C-l
-------
marketed under tradenames including AcrilarV^, Creslarr^f Orlon^/, and
ZefrarWv are used in the manufacture of apparel, carpeting,
blankets, draperies, and upholstery. Some applications of mod-
acrylic fibers are synthetic furs and hair wigs; tradenames for
/rh /f?k _/R) ./R}
modacrylic fibers include Acrylarr-', Elura^, SEF-', and Verer^.
Acrylic and/or modacrylic fibers are manufactured from acryloni-
trile by American Cyanamid Company (Milton, Florida), Dow Badishe
Company (Williamsburg, Virginia), E. I. du Pont de Nemours and Com-
pany, Inc. (Camden, South Carolina and Waynesboro, Virginia), East-
man Kodak Company (Kingsport, Tennessee), and Monsanto Company (De-
catur, Alabama) [National Institute for Occupational Safety and
Health (NIOSH), 1977].
Other major uses of acrylonitrile include the manufacture of
acrylonitrile-butadiene-styrene (ABS) and styrene-acrylonitrile
(SAN) resins (used to produce a variety of plastic products),
nitrile elastomers and latexes, and other chemicals (e.g., adipo-
nitrile, acrylamide). Acrylonitrile has been used as a fumigant;
however, all U.S. registrations for this use were voluntarily with-
drawn as of August 8, 1978 (43 FR 35099). The U.S. Food and Drug
Administration (FDA) has recently banned the use of an acryloni-
trile resin for soft drink bottles (Anonymous, 1976, 1977b, 1978),
but its use is still allowed in other food packaging. NIOSH esti-
mates that 125,000 persons are potentially exposed to acrylonitrile
in the workplace (NIOSH, 1977).
At the present time, the body of evidence produced in both
toxicity studies on laboratory animals and occupational epidemio-
logic studies on man suggests that acrylonitr ile may be a human
C-2
-------
carcinogen. Thus, NIOSH has recently stated that "acrylonitrile
must be handled in the workplace as a suspect human carcinogen"
(NIOSH, 1978a). This judgment of NIOSH was based primarily on (1)
a preliminary epidemiologic study of E. I. du Pont de Nemours and
Company, Inc. of acrylonitrile polymerization workers from one
particular textile fiber plant (Camden, South Carolina); in this
study, it was ascertained that a substantial excess risk (twice
that expected) of lung and colon cancers occurred between 1969 and
1975 in a cohort exposed between 1950 and 1955 (O'Berg, 1979); (2)
interim results from ongoing 2-year studies on laboratory rats per-
formed by the Dow Chemical Company, and reported by the Manufactur-
ing Chemists Association (April, 1977) in which, by either drinking
water (Quast, et al. 1980) or inhalation routes (Maltoni, et al.
1977) of acrylonitrile exposure, laboratory rats developed CNS
tumors and Zymbal's gland carcinomas, not evident in control
animals.
Aside from suggestive evidence of carcinogenicity in man and
animals, other genotoxic characteristics of acrylonitrile (embryo-
toxicity, mutagenicity and teratogenicity) in laboratory animals
have been reported (Venitt, et al. 1977; Milvy and Wolff, 1977;
Murray, et al. 1976). Although there is some controversy over the
chronic effects of acrylonitrile (Shaffer, 1977), the acute toxi-
city of acrylonitrile is well known and the compound appears to
exert part of its toxic effect through the release of inorganic
cyanide (Fassett, 1963; Wilson, 1944).
In this compilation of the human health effects and hazard
evaluation of acrylonitrile, several reviews were consulted (Grahl,
C-3
-------
1970; Fassett, 1963; NIOSH, 1978a). Much of the literature relat-
ing to occupational exposure and epidemiology is either Russian or
East European in origin and, for the most part, only abstracts of
these works were consulted.
Most of the work available regarding contamination of water
supplies with acrylonitrile is in the foreign literature and deals
primarily with either the use of polyacrylonitrile for filtration
of industrial wastes or the biological treatment of waste effluents
from acrylonitrile plants (Verkhovykh, et al. 1975; Skakihara, et
al. 1976; Pradt and Meidl, 1976). Research regarding the monitor-
ing of acrylonitrile in drinking water was not available for con-
sideration. This is not unexpected because of the fact that only
recently have the possible genotoxic effects of acrylonitrile been
discovered.
Acrylonitrile is the most extensively produced aliphatic
nitrile and ranks 45th on the list of high volume chemicals pro-
duced in the United States (Anonymous, 1978a). The 1976 production
of acrylonitrile was 1.6 billion pounds (Anonymous, 1978b) which is
approximately 7 times the 1960 production volume.
Approximately 125,000 individuals in the United States are
exposed to acrylonitrile monomer during its manufacture and poly-
merization or during its molding to acrylonitrile-based polymers
including Dralong T, Barex 210, Lopac, butadiene-acrylonitrile, and
polyacrylonitrile (NIOSH, 1977). Disposal of acrylic polymers,
including polyacrylonitrile, by burning results in the release of
acrylonitrile monomer (Rumberg, 1971). Residual amounts of acrylo-
nitrile monomer are released from fabrics such as underwear made of
C-4
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polyacrylonitrile fiber (Rapoport, et al. 1974), and from furniture
and other items made of polyacrylonitrile plastics (Vol'skii, 1973).
The public may also be exposed to acrylonitrile by ingestion of
food products which have leached residual acrylonitrile monomer
from polyacrylonitrile packaging materials, such as commercial
plastic wraps for foods (Anonymous, 1977a).
Cigarette smoke has been shown by gas chromatographic analysis
to contain aliphatic nitriles including acrylonitrile, propioni-
trile, and methacrylonitrile (Izard and Testa, 1968). The presence
of aliphatic nitriles in cigarette smoke may explain why Mallette
(1943) found higher values of thiocyanate (a known metabolic prod-
uct of acrylonitrile) in the blood and urine of acrylonitrile works
who were smokers compared to nonsmokers.
In summary, besides occupational exposure of those involved in
the manufacture and processing of aliphatic nitriles, the public is
exposed to acrylonitrile from the burning of acrylonitrile-based
polymers, by release of residual monomer from acrylic fibers and
plastics, by leaching of monomer from food packaging, and from
cigarette smoke.
Some environmental monitoring for acrylonitrile has been
reported by the Midwest Research Institute (MRI, 1978). Limited
analyses of air, water, and soils at several sources and ambient
locations throughout the United States resulted in the occasional
detection of acrylonitrile. The values obtained are summarized in
Table 1.
C-5
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TABLE 1
Acrylonitrile Concentrations in Air, Soil, and Water
from Various Locations in the U.S.
Location
(source)
Fortier, Louisiana
(American Cyanamid)
Linden, New Jersey
(American Cyanamid)
Texas City, Texas
(Monsanto)
Decatur, Alabama
(Monsanto)
Camden, S. Carolina
(du Pont)
Waynesboro, Virginia
(du Pont)
Washington, West Virginia
(Borg-Warner)
Maximum
Acrylonitrile Concentrations*
Air., Water** Soil**
(ng/nT)
-------
EXPOSURE
Ingestion from Water
While no data on monitoring of water supplies for the presence
of acrylonitrile were found in the literature, potential problems
may exist. Because toxic manifestations in animals have been
elicited by this route of administration, this source of exposure
is potentially an important one.
There are limited data on the fate of acrylonitr ile in the
aqueous environment. It is known that acrylonitrile is water
soluble (Table 2) and is hydrated readily at 100°C by 84.5 percent
sulfuric acid to produce acrylamide sulfate (Kirk and Othmer,
1967) . Whether this reaction occurs in the natural environment is
unknown.
Acrylonitrile is known to undergo photodegradation to satu-
rated derivatives. When left standing, especially in the presence
of light, a yellow color may develop, possibly due to polymeriza-
tion (Kirk and Othmer, 1967). Acrylonitrile is also subject to
biodegradation (Kuchinskii, et al. 1977; Panova, et al. 1977; Anon,
1977; Schnee, et al. 1977; Kato and Yamamura, 1976; Mikami, et al.
1974) . Measurement of biochemical oxygen demand has shown 25 to 70
percent degradation within 10 days (Hann and Jensen, 1970). Zabe-
zhinskaya, et al. (1962) studied the persistence of acrylonitrile
in the water column, noting that at an initial concentration of 10
mg/1, only 46 percent remained after 24 hours, 19 percent after 48
hours, and 5 percent after 96 hours. This would tend to minimize
the ingestion of acrylonitrile in water. A study by Midwest Re-
search Institute (1977) investigated the stability of 10 ppm
C-7
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TABLE 2
Solubility of Acrylonitrile in Water as a
Function of Temperature*
Solubility of
Acrylonitrile in
Temperature, °C Water (grams/deciliter)
0 7.2
20 7.35
40 7.9
60 9.1
*Source: Kirk and Othmer, 1967.
C-8
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acrylonitrile in distilled water and Mississippi River water.
Little decomposition occurred after 23 days in distilled water. In
river water, however, total decomposition occurred by day 6.
Adjusting to a pH of 4 had a stabilizing effect in that 67 percent
of acrylonitrile was present at 23 days. Adjusting to a pH of 10
delayed decomposition up to six days but total decomposition
occurred by day 23.
Possible sources of acrylonitrile in the aqueous environment
(either surface water, ground water, or drinking water) are: (a)
dumping of chemical wastes; (b) leaching of wastes from industrial
landfills or holding lagoons; (c) leaching of monomers from poly-
meric acrylonitrile; (d) precipitation from atmospheric rain; and
(e) loss during transfer and transport (Hardy, et al. 1972). The
first four sources listed are worthy of additional comment, and are
discussed here.
Dumping of chemical wastes: Acrylonitrile monomer waste pro-
ducts are dumped by industrial companies directly into surface
waters or sewage. Acrylonitrile has been used as a fumigant for
stored foodstuffs either alone or in a mixture with carbon tetra-
chloride, (Fishbein, 1976), methylbromide (Dumas and Bond, 1977),
and other chemicals (Heuser and Scudamore, 1968). Though no longer
in use, stored quantities of these fumigants may be being dumped by
the former manufacturers or the users.
The question of biotransformations of acrylonitrile in waste
water, its effect on bacteria and particularly on biological sewage
treatment processes such as the activated sludge treatment process
are poorly understood. However, Chekhovskaya, et al. (1966) have
C-9
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observed the effects of acrylonitrile and related compounds on
saprophytic microorganisms and bacterial processes of ammonifica-
tion and nitrification. It was found that acrylonitrile at 150
rog/1 (ppni) was utilized by saprophytic microorganisms and that
acrylonitrile at 50 mg/1 inhibited nitrification. This suggests
that acrylonitrile, entering an activated sludge process in concen-
trations of 50 ppm or greater, may inhibit certain bacterial pro-
cesses such as nitrification. Cherry, et al. (1956) reported that
microbial activity could substantially reduce initial acryloni-
trile concentrations of 10, 25, and 50 ppm. They noted also that
while the two lower concentrations supported a mixed population of
microorganisms, the 50 ppm concentrations favored the growth of
fungi. This observation supports the findings of Chekhovskaya, et
al. (1966) on inhibition of nitrification at 50 ppm and above.
Other workers have shown similar reductions of acrylonitrile con-
tent in wastewater by microorganisms (Mikami, et al. 1974; Kato and
Yamamura, 1976).
Leaching of wastes from industrial landfills or holding la-
goons: Industrial chemical or pesticide wastes, placed in holding
tanks or lagoons, may spill over into surface waters as a result of
excessive rainfall. These same wastes may also be buried in indus-
trial landfills. If the buried containers are damaged, rainfall
may leach out the acrylonitrile, and providing that the soil is
permeable, permit its movement into proximal ground water.
Leaching of monomers from polymeric acrylonitrile: It is well
known that residual amounts of monomers are commonly retained in
polymers; for example, vinyl chloride is leached out of PVC pipes
C-10
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and into drinking water (Dressman and McFarren, 1978). Russian
investigators have reported that acrylonitrile and other monomers
in finished polymers were detected in the range of 30 to 3,000 ppm
(Klescheva, et al. 1970). Therefore, the acrylonitrile monomer can
also be leached from waste polymers buried in landfills in the man-
ner described above. Acrylonitrile is also leached by water from
polyacrylonitrile plastic bottles [Natural Resources Defense Coun-
cil (NRDC), 1976J.
Precipitation of acrylonitrile from atmospheric rain: Acrylo-
nitrile has a very high vapor pressure (112 torr at 25°C) (Kirk and
Othmer, 1967). Therefore, it will volatilize substantially from
various sources even at room temperature (see Inhalation section).
Being present in the atmophere either as vapor per se or adsorbed
to particulates, it is susceptible to precipitation from the atmos-
phere in rain or snow and eventually could be present in either
surface or ground waters.
Release of acrylonitrile from transfer and transport acci-
dents: Acrylonitrile may be spilled during the process of transfer
and/or transportation, resulting in air and/or water contamination.
Ingestion from Food
The likelihood of acrylonitrile residues existing on food is
high (Casarett and Doull, 1975; Fishbein, 1976; Dumas and Bond,
1977; Heuser and Scudamore, 1968). Dumas and Bond (1977) noted
that acrylonitrile was desorbed very slowly from foods depending on
the type of commodity and aeration conditions. Polyacrylonitrile
containers (margarine containers, wrapping material, etc.) retain
C-ll
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residual amounts of the monomer which may then be leached into the
food and subsequently ingested by the consumer (NRDC, 1976).
Although FDA has banned the use of polyacrylonitrile plastic
in soft drink bottles (Anonymous, 1976, 1977b, 1978), attempts to
lift this ban by the producing companies are in progress. The FDA
has restricted the monomer residue to about 80 ppm in the finished
products and a restriction to 11 ppm was pending as of 1976 (NRDC,
1976). The currently produced soft drink container includes about
20 ppm acrylonitrile of which as much as 0.3 ppm acrylonitrile and
0.2 ppm HCN are reported to leach into hot water (NRDC, 1976).
A bioconcentration factor (BCF) relates the concentration of a
chemical in aquatic animals to the concentration in the water in
which they live. The steady-state BCFs for a lipid-soluble com-
pound in the tissues of various aquatic animals seem to be propor-
tional to the percent lipid in the tissue. Thus, the per capita
ingestion of a lipid-soluble chemical can be estimated from the per
capita consumption of fish and shellfish, the weighted average per-
cent lipids of consumed fish and shellfish, and a steady-state BCF
for the chemical.
Data from a recent survey on fish and shellfish consumption in
the United States were analyzed by SRI International (U.S. EPA,
1980). These data were used to estimate that the per capita con-
sumption of freshwater and estuarine fish and shellfish in the
United States is 6.5 g/day (Stephan, 1980). In addition, these
data were used with data on the fat content of the edible portion of
the same species to estimate that the weighted average percent
C-12
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lipids for consumed freshwater and estuarine fish and shellfish is
3.0 percent.
A measured steady-state bioconcentration factor of 48 was
obtained for acrylonitrile using bluegills (U.S. EPA, 1978). Simi-
lar bluegills contained an average of 4.8 percent lipids (Johnson,
1980). An adjustment factor of 3.0/4.8 = 0.625 can be used to
adjust the measured BCF from the 4.8 percent lipids of the bluegill
to the 3.0 percent lipids that is the weighted average for consumed
fish and shellfish. Thus, the weighted average BCF for acryloni-
trile and the edible portion of all freshwater and estuarine
aquatic organisms consumed by Americans is calculated to be 48 x
0.625 = 30.
Inhalation
The current estimate in the U.S. for the number of individuals
involved in the manufacture and polymerization of acrylonitrile is
125,000 (NIOSH, 1978b). Therefore, a considerable population is at
high risk from occupational exposures, particularly through inhala-
tion. Analyses of atmospheric air from an acrylic fiber plant in
which a large fraction of the coworkers complained of symptoms of
illness revealed concentrations of acrylonitrile of 3 to 20 mg/m
(Orusev and Popovski, 1973).
Workers involved in acrylonitrile synthesis or its polymeriza-
tion are not the only occupational groups subject to acrylonitrile
exposure; workers in plastic (polyacrylonitrile) molding factories
are similarly at risk (Scupakas, 1968). Scupakas (1968) studied
the working conditions in an old factory producing thermosetting
plastics by molding and noted various toxic manifestations in
C-13
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employees including dermatitis, disorders of CNS, chronic upper
respiratory tract irritation, and other symptomatology when the
acrylonitrile concentration in the in-plant environment was 1.4
mg/m . However, various other compounds were present in the in-
plant atmosphere including phenol, formaldehyde, ammonia, HC1,
butyl phthalate, and carbon monoxide. Timofievskaya (1968) and
Duvall and Rubey (1973) reported that various types of acryloni-
trile polymers underwent decomposition to various nitriles, NO ,
X
unsaturated hydrocarbons, etc. either under molding conditions (40
to 400°C) or heating (40 to 80°C) and/or burning (200 to 600°C) .
The nature of the products formed were highly dependent on combus-
tion conditions and contained significant amounts of highly toxic
compounds. Some of the polymers studied included Dramalon T; poly-
acrylonitrile fiber; Barex 210 (3:1 acrylonitrile-methylacrylate
copolymer); Lopac (9:1 methacrylonitrile-styrene copolymer); and
1,3 butadiene-nitrile rubber. It is clear that burning of acrylic
polymers, including polyacrylonitrile, represents a great poten-
tial occupational and/or environmental hazard due to the release of
high concentrations of acrylonitrile, other substituted vinyl com-
pounds, HCN, NO , and other undetermined compounds (Table 3) . In
A
addition, it is likely that various significant interactions be-
tween the compounds occur (Hilado, et al. 1976; LeMoan and Chaig-
neau, 1977).
Though data are unavailable on monitoring the ambient atmos-
phere for the presence of acrylonitrile, the stack gases from syn-
thesis and polymerization plants for acrylonitrile may well be dis-
charging significant amounts into the atmosphere. As noted above,
C-14
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TABLE 3
Pyrolysis of Lopac as a Function of Temperature
Using Porapak N Column*
Pyrolysis
Temperature(°C)
116
188
230
260
260
290
330
500
570
740
Pyrolysis Products
No compound observed
NH3 (trace)
NH3
NH,
NH3- HCN (trace); acrylonitrile
Air; CO; C02; C2H2; NH3, HCN;
acetonitrile, acrylonitrile,
propionitrile; pyrrole
Air* CO* CO • c H • c H • *JH
acetonitrile; acrylonitrile;
pyrrole
Air; CO;
C2H4
C2H2
NH
acetonitrile; acrylonitr ile;
pyrrole
HCN;
HCN;
*Source: Monsanto, 1973
C-15
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another potentially significant ambient source of acrylonitrile and
related compounds in air is the outside burning of acrylonitrile
polymers. While it is known that acrylonitrile reacts photochemic-
ally in the vapor phase (Kirk and Othmer, 1967), no detailed data
were available to the authors on the actual reactivity (ti ) of
acrylonitrile in the atmosphere in ppm or ppb concentrations.
Vol'skii, et al. (1973) have noted that the amount of plastic
and synthetic rubber furniture on boats must be limited to -^c.10.8
kg of LKF-2 plastic/m air to avoid an accumulation of monomers
such as acrylonitrile vaporizing under the influence of the unusual
combination of living conditions (humidity, heat, and light). The
authors recommend adequate ventilation. Undoubtedly, the same
findings apply to homes. In a recent report, Rapaport, et al.
(1974) have indicated that traces of acrylonitrile were detected in
the air surrounding underwear made from polyacrylonitrile fibers.
Acrylonitrile, and a variety of other nitriles, have been found by
gas chromatography to be components of cigarette smoke; the amounts
were not quantified (Izard and Testa, 1968).
Inhalation has been reported to be the major route of exposure
in lethal cases of acrylonitrile poisoning (Radimer, et al. 1974).
When man breathes air containing 20 yg acrylonitrile/1 (20,000
ug/m ) the average retention of acrylonitrile vapors was found to
be 46 percent (Rogaczewska and Piotrowsky, 1968) . A later study by
Young, et al. (1977) found with rats that retention was greater
than 90 percent (see Pharmacokinetics section).
C-16
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Dermal
Acrylonitrile has exhibited toxic effects on experimental ani-
mals by skin absorption (Hashimoto and Kanai, 1965; Egorov, et al.
1976). Anton'ev and Rogailin (1970) have reported that skin con-
tact is one of the most important routes for acrylonitrile absorp-
tion in plant workers and that the absorption of acrylonitrile
applied to the forearm skin averaged 0.6 mg/cm -hr. Egorov, et al.
(1976) have determined the threshold doses for dermal absorption of
acrylonitrile and other compounds in terms of a one-time applica-
tion to the skin as well as a 4-month long chronic application. The
value for acrylonitrile was estimated to be 0.11 mg/kg body weight.
The maximum permissible contamination level for the skin of the
hands of workers was determined to be 0.7 mg of acrylonitrile. It
is not clear from the abstract whether the experiment was done on
laboratory animals and extrapolated to man or performed directly on
man. Dermatologic conditions including contact allergic derma-
titis, occupational eczema, and toxodermia in acrylonitrile workers
have been discussed by Dovzhanskii (1976a), Balda (1975), Malten
(1973), and Anton'ev and Rogailin (1970) and show the importance of
the dermal route in occupational exposure. That there is a hyper-
sensitivity response to acrylonitrile has been discussed by Dov-
zhanskii (1976a), Balda (1975), and Khromov (1974).
Because of the paucity of data available on acrylonitrile, it
is difficult to assess quantitatively the contribution of each
route of exposure to the total dose in man; it is likely that the
greatest contribution comes via inhalation, particularly in an
occupational setting. The next most likely route is dermal and the
C-17
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least likely is ingestion. Figure 1 is a schematic representation
of the various modes of exposure of man to acrylonitrile.
PHARMACOKINETICS
Absorption and Distribution
Attempts were not made to separate these categories due to the
limited data available at the time of document preparation. Subse-
quently, a study on the pharmacokinetics of 1-14C labeled acrylo-
niltrile became available from the Manufacturing Chemists Associa-
tion. Details of this study are included at the end of this
chapter.
Blood concentrations of acrylonitrile and cyanide as a func-
tion of time after exposure have been studied in relation to toxi-
city (Hashimoto and Kanai, 1965). In the rabbit at a sublethal
dose (30 mg/kg, LD^g = 75 mg/kg) a typical blood concentration ver-
sus time curve was observed. Acrylonitrile rapidly disappeared
with 1 ppm of acrylonitrile remaining four hours after exposure.
Thiosulfate accelerated the urinary excretion of thiocyanate (SCN )
as a metabolite and somewhat reduced the toxicity of acrylonitrile;
however, the blood concentration versus time curve was not changed
(Hashimoto and Kanai, 1965). L-cysteine administered prior to
acrylonitrile resulted in 80 percent reduction of acrylonitrile
peak blood levels and 30 percent reduction of its toxicity. Un-
changed acrylonitrile was detected in the urine of the rabbit 72
hours after exposure and in expired air one hour after dosing. In
guinea pig urine, acrylonitrile was detected 24 hours after admin-
istration by gavage to 15 mg/kg. Urinary and expiratory excretion
of unchanged acrylonitrile accounted respectively for only 3 and 10
C-18
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PREDICTED SOURCES OF HUMAN EXPOSURE
TO ACRYLONITRILE
FOOD
(Pesticide residue
and monomer from
wrapping plus
bioaccumulation in
fish from water )
AMBIENT
AIR DRINKING WATER
(Acrylonitrile vapor (Dissolved Acrylonitrile)
plus adsorbed layer
on suspended
particulcte )
SMOKING •-
(Monomer and
other nitriles in
cigarette smoke)
EXPOSURE
TO
MAN
/ \
(
COMBUSTION OF
SYNTHETIC POLYMERS
(Acrylonitrile and other
toxic products in
vapors and particulate)
OCCUPATIONAL
(From ocrylonitrile,
polyaaylonitrile,
manufacturing plants,
fiber production,
molding, etc.)
OTHER SOURCES
(Acrylonitrile monomer from
clothing, furniture, dental
materials, etc. )
FIGURE 1
Predicted Sources of Human Exposure
C-19
-------
percent of the dose (15 mg/kg) while urinary thiocyanate accounted
for 14 percent of the dose (Hashimoto and Kanai, 1965). The re-
mainder was probably metabolized via direct enzymatic or nonenzy-
matic conjugation with nucleophilic compounds such as, cysteine,
glutathione, and free or conjugated basic amino acids. Alterna-
tively, the remainder may undergo enzymatic oxidation or reduction.
A detailed metabolic study is required to elucidate the toxico-
kinetics of acrylonitrile.
Fat tissue accumulation of acrylonitrile may also occur.
While the high solubility of acrylonitrile in water (7.35 percent
at 20°C, Kirk and Othmer, 1967) would permit the excretion of the
unchanged compound in the urine, the urinary detection 72 hours
after exposure in the rabbit strongly suggests either fat storage
or reversible protein binding. Czajkowska (1971) has studied the
excretion of metabolites after a single intraperitoneal (i.p.) dose
(60 to 70 mg/kg) of acrylonitrile in rats. The main urinary metab-
olite in rats was SCN~; its excretion within 72 hours amounted to
8.5 percent of acrylonitrile intake. The SCN~ excretion half-life
was 13 hours. No cyanide was detected in rat urine within 24 hours
following the single dose, while only traces of acrylonitrile were
observed.
Metabolism
Earlier reports (Giacosa, 1883; Meurice, 1900) indicated that
most aliphatic nitriles are metabolized to cyanide which is then
detoxified to thiocyanate. Levels of cyanide and thiocyanate were
elevated in the blood and present in the urine of acrylonitrile-
treated animals. Brieger, et al. (1952) observed elevated levels
C-20
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of cyanide, thiocyanate (SCN~), and cyanomethemoglobin in the blood
of animals treated with acrylonitrile. The author concluded that
acrylonitrile exerts its toxicity by the metabolic release of cya-
nide ion, and that the relative ability of various species to con-
vert CN~ to SCN~ determined their susceptibility to the toxic
action of acrylonitrile (Brieger, et al. 1952). A later study by
Boyland and Chasseaud (1967) indicates, however, that the toxicity
of acrylonitrile is due in part to the molecule itself. It was
found that the urinary excretion of thiocyanate after acrylonitrile
administration ranged from 4 to 25 percent of the administered dose
(Brieger, et al. 1952; Czajkowska, 1971; Gut, et al. 1975; Efremov,
1976; Paulet and Desnos, 1961; Benes and Cerna, 1959; Dudley and
Neal, 1942; Hashimoto and Kanai, 1965). Brieger, et al. (1952)
noted that in dogs (a species particularly susceptible to acrylo-
nitrile) , the relative concentration of cyanomethemoglobin in-
creased with length of exposure, with most of the available methe-
moglobin converted to cyanomethemoglobin by the end of the lethal
exposure period.
Using Wistar rats, albino mice, and Chinese hamsters, Gut, et
al. (1975) found that the extent of conversion of acrylonitrile to
cyanide was dependent on the route of administration, decreasing in
the following order: oral (>2Q%) >i.p. = s.c. (2 to 4%) >. i.v.
(1%) . Thus, the more slowly acrylonitrile enters the system, the
more extensively it is converted to cyanide. This suggests that
conversion of acrylonitrile to cyanide involves metabolic processes
competing with blood protein binding and nonenzymatic cyanoethyla-
tion. Pretreatment of rats with phenobarbital, SKF 525A, cysteine,
C-21
-------
or dimercaprol (BAL) did not significantly influence elimination of
SCN in the urine after acrylonitrile administration; however,
simultaneous administration of thiosulfate and acrylonitrile sig-
nificantly increased the metabolized portion (thiocyanate) of
acrylonitrile given to rats by twofold and mice by threefold. Pre-
treatment with Aroclor*^ 1254 was found to greatly enhance the tox-
icity of acrylonitrile, and to cause a threefold increase in the
cyanide level in the blood of treated rats; Gut, et al. (1975)
found acrylonitrile to be strongly bound in blood. Acrylonitrile
was metabolized to SCN~ more effectively by mice than by rats fol-
lowing oral, i.p., and intravenous (i.v.) administration. Possible
differences in the mechanism of acrylonitrile toxicity in rats and
mice are indicated by the greater metabolism of acrylonitrile to
SCN~ and the larger decrease in its acute toxicity by thiosulfate
in mice compared with rats. Gut, et al. (1975) concluded that cya-
nide may play a more important role in the toxicity of acryloni-
trile in mice than it does in rats.
In their study, Gut, et al. (1975) offered no explanation for
the role of cysteine on the acrylonitrile SCN~ balance, nor do they
explain cysteine's protective mechanism against acrylonitrile tox-
icity. If cysteine is protecting the animal by reaction with
acrylonitrile via formation of cyanoethylcysteine, thiocyanate
levels should decrease, and if it enhances cyanide metabolism,
thiocyanate levels should increase. However, pretreatment with
cysteine had no effect on thiocyante levels.
In vitro, it was implicated that acrylonitrile was conjugated
with glutathione (GSH) via a GSH transferase enzyme. The conjugate
C-22
-------
of this reaction was not detected; rather conjugation was measured
indirectly by disappearance of the GSH substrate (Boyland and Chas-
seaud, 1967). Although uptake of acrylonitrile gives rise to a
slight increase in cyanomethemoglobin, combined therapy with
nitrite and thiosulfate affords partial protection against its
toxic action. These facts suggest that acrylonitrile toxicity is
due in part to the acrylonitrile molecule itself or other unknown
metabolite(s) rather than just the cyanide functional group. Only
traces of unchanged acrylonitrile were detected in the urine of
acrylonitrile-treated rats (Czajkowska, 1971). This suggests that
the major portion of the compound is altered in the body to other
metabolites or conjugates such as indicated in the following scheme
proposed.
Proposed pathways for acrylonitrile biotransformation are
presented in Figure 2 (A. Ahmed, personal communication). Cyano-
ethylated products (top pathway) of cell macromolecules and of cir-
culating nucleophiles can be recovered in tissue fractions and in
biologic fluids. If the proposed pathway is correct cyanoethylated
glutathione conjugates should be recoverable in bile and urine.
One, in fact, has been found - cyanoethylated mercapturic acid (A.
Ahmed, personal communication). Oxidation by the mixed function
oxidases or another enzyme system could lead to an epoxide which
could be enzymically hydrated, could rearrange, or be acted upon by
glutathathione transferase. In either case, soluble oxidized prod-
ucts would be produced and cyanide would be liberated. Products of
the proposed oxidation pathways, including glyoxalic acid, oxalic
C-23
-------
LNucltic acids (NH, OH)
IProtaina (NHj, OH, SMI
. ISioiogical Nauroiranionittara • aiAdranaiin* and its analogs
* 01 Swatonin oY-AminoOutyrlc acid d) Hislomin*
4.otlwr nuclaooAilic co of tisauas
CH,-CH—en
SCMj-CHjCN
cyano«inylaiad
nwrcapluric acid
hydra* tnmtff CHj—CCN-w:H3COH *• HCN
cyiniO* trintltf CHj—C
CN NOH
cyanoacaiic acid
QSH trtmftnt*
\
OH
GS-CH-CM
CN
\
H
CH,
COOH
CHO
HCN
N-actiyiatkw
-n«rcaetu.'.c
acid
FIGURE 2
Proposed Pathways for Acrylonitrile Biotransformation
C-24
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acid, acetic acid, cyanoacetic acid, and cyanide are soluble and
should be detectable in blood or urine.
Most recently, Young, et al. (1977) published the results of a
comprehensive radiotracer study in which 1- C labeled acryloni-
trile was used in male Sprague-Dawley rats to determine dose and
route dependency of the pharmacokinetics of this compound. The
position of the radiotag allowed tracking of the three carbon chain
metabolites as well as the one carbon cyano moeity. Three major
routes of administration were used with the following dose varia-
tions:
Route Doses
Ingestion via single
oral dose of aqueous 0.1 mg/kg 10 mg/kg
solution.
Inhalation of 6 hours
duration from a
"nose only" 5 ppm 100 ppm
chamber Calc. mean dose = 0.7 mg/kg 10.2 mg/kg
Intravenous injection 10 mg/kg
The major conclusions of this study are highlighted in the fol-
lowing :
Absorption: When orally administered to rats, essentially all
of the acrylonitrile is absorbed and metabolized. Only 5 percent
of the dose is excreted with the feces in the form of metabolites.
Metabolism: Qualitatively, CO 2 and three unidentified metabo-
lites, A, C, and E were identified in the rat. These metabolites
(A, C, and E) were excreted primarily in the urine, while CC^ was
primarily exhaled with breath. Chemical identities of compounds A,
C, and E were not elucidated, but contrary to prior suspicion none
C-25
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of these were acrylamide. Metabolite C predominated at low doses
followed by compound A while molecule E was present in trace quan-
tities. This ratio changed at high dose when A drastically in-
creased. Recovery of total radioactivity in metabolites, A, C, E,
and CO- exceeded 94 percent.
Distribution: The metabolites of acrylonitrile were rapidly
distributed to all tissues. Plasma concentration of radioactivity
remained at similar levels without regard to route or dose. Metab-
olites E and C were reabsorbed from the small intestine and metabo-
lite E underwent enterohepatic circulation. The enterogastric and
enterohepatic phenomena could account for the retention of the
radioactivity in the body. Metabolite E was found in the erythro-
cytes, where its half-life was significantly longer than in other
storage sites. This latter observation suggests that metabolite E
forms adducts with red cell constituents. This in turn may imply
that the red cell serves as an accumulator of chronic acrylonitrile
insult in the body, and therefore may be used for biological mon-
itoring of exposure. Independently of dose or route of administra-
tion metabolite E was selectively accumulated in the stomach
(glandular and nonglandular portion of the stomach wall).
Even after the total body burden of C declined and after the
14
C concentration of stomach contents diminished, the stomach up-
take remained at a positive slope. This finding reinforces phe-
nomena previously observed in rats, namely the emergence of gastric
papillomas even though the route of exposure was other than oral.
In a similar fashion the skin accumulated acrylonitrile metab-
olites which rose to 2 to 3 times over plasma levels. Possible
C-26
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interfering effects of skin absorption from the exogeneous gas
phase must be discounted because the investigators used a "nose
only" type of inhalation chamber. While the mechanism of skin
absorption is unknown, it is plausible that the abundance of the
sulfhydryl groups in the skin protein matrix may be responsible for
the effects seen.
Dose dependency of metabolism: Metabolite C was found to be
the main liver metabolite, which after bile excretion was readily
re-absorbed from the small intestine and excreted in the urine.
Only a very small portion of the total dose-load appeared in the
form of compound A. After administration of high doses however,
compound A strikingly increased. The formation of metabolite E was
time dependent and did not occur significantly in the first eight
hours after administration. An iri vitro study using rat liver
homogenate (9,000xg) supernate indicated that the liver is not the
chief site for the formation of compound E. In addition, the very
early appearance of metabolite E in the red cells suggests extra-
hepatic sites (perhaps a red cell enzyme) for the formation of this
molecule.
C02 could arise as a product of cyanate metabolism. Although
thiocyanate was shown to be the main product of cyanide metabolism
(Boxer and Richards, 1952) these authors have shown that cyanide
can be metabolized to carbon dioxide via the cyanate ion. In fact,
this study demonstrated a strong dose dependence of cyanide metabo-
lism in dogs. It is plausible that the dose dependence of acrylo-
nitrile pharmacokinetics may result in part from differences in the
fate of the cyanide formed.
C-27
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Excretion
The dose and route dependent variations in the metabolic fate
of acrylonitrile are most likely due to shifts in metabolic path-
ways associated with hepatic and extrahepatic origin. Therefore
the authors conclude: "extrapolation of the results of toxico-
logical studies conducted by one route to expected toxicity at the
same dosage by another route (a common practice) may not be valid
for acrylonitrile because of its route dependent fate; likewise,
extrapolation from toxicological data at one dose level to a dif-
ferent, untested, dose level cannot be done with confidence because
of the dose dependent fate of acrylonitrile in the body".
This conclusion creates some uncertainty in the use of the
linear nonthreshold model for calculating the acceptable risk con-
centration in water for man exposed to acrylonitrile (see Carcino-
genicity section). However, the data presented by Young, et al.
(1977) did not indicate that the metabolites whose fate was dose-
dependent was necessarily the cancer inducing material. Therefore,
until these data are experimentally developed the linear model can
still be applied.
EFFECTS
Acute, Subacute, and Chronic Toxicity
Dudley and Neal (1942) reported that a 4-hour exposure by
inhalation to 635 ppm acrylonitrile was fatal to rats, while a
4-hour exposure to a lower level, 100 ppm, was fatal to dogs. Sub-
sequent animal experiments have shown that acrylonitrile is acutely
toxic by all routes of administration including inhalation, oral,
subcutaneous and cutaneous exposure (NIOSH, 1978b).
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Table 4 lists the toxic effect levels for different species
(NIOSH, 1977). Acrylonitrile toxicity varies between species (Wil-
son and McCormick, 1949). Mice are very sensitive to acrylonitrile
and suffer a severe decrease in body weight with a slight change in
blood picture (Hashimoto, 1962). Benes and Cerna (1959) observed
that rats have higher resistance to acrylonitrile exposure; they
developed delayed symptoms and high levels of thiocyanate in urine
and blood. Dudley, et al. (1942) reported that inhalation exposure
of rats to 56 ppm x 4 hours, 5 days a week, for 8 weeks resulted in
irritation of the respiratory mucous membrane with hyperemia, lung
edema, alveolar thickening, and hemosiderosis of the spleen. Cen-
tral nervous system disorders were also observed.
A 90-day toxicity study, conducted by Dow Chemical Company,
incorporating 200 and 300 ppm of acrylonitrile in the drinking
water of rats resulted in the animals' death before the end of the
study (NRDC, 1976). Knobloch, et al. (1972) observed a perceptible
change in peripheral blood pattern, functional disorders in the
respiratory and cardiovascular systems and the execretory nephron
system as well as signs of neuronal lesion in the CNS of rats and
rabbits breathing acrylonitrile (50 mg/m3 air) for six months. In
addition, they reported irritation of the mucosa when acrylonitrile
concentration in the air was increased to 250 mg/m . Graczyk and
Zwierzchowski (1973) reported that i.v. administration of 13 to 110
mg acrylonitrile decreased the pressor effects of epinephrine,
norepinephrine, and acetylcholine. When injected s.c. at 0.5
mg/rat/day for 10 days, acrylonitrile decreased the rate of 02 UP~
take and increased that of glycolysis in brain (Solov'ev, et al.
C-29
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TABLE 4
Toxic Levels of Acrylonitrile for Different Species*
Species
Rat
Mouse
Dog
Cat
Rabbit
Guinea Pig
Route
Oral
Inhalation
S.C.
Oral
Inhalation
I. P.
Inhalation
Inhalation
Oral
Inhalation
Skin
Oral
Inhalation
Effect
LD50
LCLO
LD50
LD50
LCLo
LDLO
LCLo
LCLO
LD50
LCLo
LD50
LD50
LC50
Dose
82
500
96
27
784
10
110
600
93
258
250
50
576
mg/kg
ppm/4 hr
mg/kg
mg/kg
ppm/1 hr
mg/kg
mg/kg/4 hr
ppm/4 hr
mg/kg
ppm/4 hr
mg/kg
mg/kg
ppm/4 hr
*Source: NIOSH, 1978b.
C-30
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1972) . Acrylonitrile did not effect the levels of ATP or cre-
atinine phosphate. Solov'ev, et al. (1972) also reported an in-
crease in the activity of phosphofructokinase and a decrease in the
glycogen level in cerebral tissue.
Knobloch and Szendzikowski (1971) reported that the LD^s of
acrylonitrile in rats were 80 and 100 mg/kg when given s.c. and
i.p., respectively, and 34 mg/kg when given s.c. to mice. When
inhaled with air over three weeks, the LC5Qs of acrylonitrile were
0.3, 0.47, and 0.99 mg/1 in mice, rats and guinea pigs, respec-
tively (Knobloch and Szendzikowski, 1971). They also reported that
acrylonitrile caused congestion and damage to the CNS, lungs,
liver, and kidneys. Intraperitoneal injections of 50 mg acryloni-
trile/kg daily for three weeks to adult rats resulted in body
weight loss, leukocytosis, functional disturbances in liver and
kidneys, slight damage to the neural cells of the brain stem and
cortex, and parenchymal degeneration of the liver and kidneys (Kno-
block and Szendzikowski, 1971). Krysiak and Knobloch (1971)
reported that acrylonitrile (20 mg/kg/day for six weeks or 40
mg/kg/day for four weeks) caused disturbances in the central ner-
vous system of rats as evidenced by misperformance in the labyrinth
test. In that test acrylonitrile caused marked impairment of food-
conditioned reflexes and learning ability. Babanov, et al. (1972)
reported that inhalation of acrylonitrile vapor (0.495 mg/m , 5
hours/day, 6 days/week) for six months resulted in CNS disorders
and an abnormal blood picture (increased erythrocyte count and
decreased leukocyte count) in rats. It also resulted in increased
total protein catalase and peroxidase content, decreased ascorbic
C-31
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acid content of blood serum and increased number of free sulfhydryl
groups in the liver and blood serum. Acrylonitrile given orally in
a dose of 80 mg/kg increased the content of several amino acids in
the brain (Movsumzade, 1970) . In the same study Movsumzade re-
ported that, in the liver, various pools of basic amino acids
levels were decreased to traces. He related these observations to
the damage of synthetic function of the liver and to damage of the
blood-brain barrier. Takagi, et al. (1968) studied the effect of
administration of vitamins B^ or 82 plus cysteine to rats exposed
to acrylonitrile vapor over a long period. They observed that uri-
nary excretion of thiocyanate decreased with this treatment. They
reported that exposure to acrylonitrile caused enlargement of
liver, kidney, heart, and spleen and a decline of alcohol dehydro-
genase activity in the liver; alleviation of these symptoms oc-
curred upon administration of vitamin B-, or B^ plus cysteine. A
single s.c. administration to rats of acrylonitrile at two times
the LD^Q dose decreased the liver and kidney glutathione level
greatly and increased levels of lactic acid (Dinu and Klein, 1976).
These authors also reported that catalase activity was slightly
increased but only in the liver. They concluded that the decrease
of reduced glutathione levels rendered the glutathione peroxidase
ineffective, and the increase of lactic acid concentration con-
comitantly inhibited a compensatory increase in catalase activity.
The resulting increase in the peroxide level damaged the tissue.
Dinu (1975) reported that similar doses of acrylonitrile admin-
istered orally to rats increased the hepatic levels of malonalde-
C-32
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hyde, glutathione peroxidase and catalase, which she concluded,
indicate lipid peroxidation.
Tissue protein and nonprotein sulfhydryl (reduced gluta-
thione) decreased in guinea pigs and rabbits following a single
dose of acrylonitrile (Hashimoto and Kanai, 1965; Szabo, et al.
1977; Dinu, 1975). Prior treatment with thiol compounds such as
cysteine, confers some protection against the toxic action of
acrylonitrile (Paulet, et al. 1966; Hashimoto and Kanai, 1965). An
increase in the number of free sulfhydryl groups was also observed
in the liver and serum of rats chronically treated with acryloni-
trile (Babanov, et al. 1972; Szabo, et al. 1977) . _In vitro inhi-
bition of potassium-stimulated respiration of brain cortex was
observed at a 10 M acrylonitrile concentration; little effect on
liver respiration was observed (Hashimoto and Kanai, 1965). Tar-
kowski (1968) reported that cytochrome oxidase was inhibited in
liver, kidney, and brain tissue taken from rats two hours after
i.p. administrations of 100 mg/kg acrylonitrile. In Tarkowski's _in
vitro experiments with similar tissues, inhibitions of 18 to 30
-4 -3
percent, 45 to 55 percent, and 75 to 85 percent with 10 ,10 , and
_2
10 M acrylonitrile, respectively, were obtained. Since acrylo-
nitrile did not change the spectrum of cytochrome oxidase in the
same manner as KCN, Tarkowski concluded that the toxic effect of
acrylonitrile could not be attributed to generation of cyanide.
Minami, et al. (1973) reached just the opposite conclusion. They
reported what they thought to be a high degree of similarity be-
tween the response of rabbits poisoned by acrylonitrile and rabbits
poisoned by cyanide; the blood p02/ pC02, pH, hemoglobin, and hemo-
C-33
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tocrit values were correlated with the concentration of cyanide and
thiocyanate.
Wilson and McCormick (1949) reported that acrylonitrile shows
large variations in toxicity among species. In rabbits, exten-
sive damage in the four phases of the brain nervous system was
observed. Other symptoms were shivering, tearing, redness of the
ears, and hyperemia (Benes and Cerna, 1959). Dudley, et al. (1942)
reported that guinea pigs treated with acrylonitrile (1.25 mg/1)
developed strong interstitial nephritis, bronchopneumonia, and
inflammatory lung irritation. Dogs were the most sensitive experi-
mental animals to acrylonitrile (Grahl, 1970). Thiocyanate levels
in serum and urine of dogs treated with 100 ppm acrylonitrile were
10 times higher than those of rats receiving the same dose (Lawton,
et al. 1943; Lindgren, et al. 1954). Liver and kidney damage was
less pronounced in the dogs than in rats (Brieger, et al. 1952) . In
monkeys, anoxia, brain damage, and death by suffocation were
observed upon administration of acrylonitrile (Grahl, 1970).
Acrylonitrile intoxication in cats resulted in the early onset of
liver injury (Dudley, et al. 1942) . Pathologic examination of ani-
mals following acute acrylonitrile exposure revealed all animals
had edema (Dudley and Neal, 1942; Szabo and Selye, 1971a); histo-
logic changes in the brain, particularly the cortex, characteristic
of anoxia (Brieger, et al. 1952); blood that was unusually dark red
and liquid (Dudley and Neal, 1942; Brieger, et al. 1952); and
liver and kidney damage (Knobloch, et al. 1972) . Pathologic exami-
nation following repeated acrylonitrile administration revealed
slight damage to the neural cells of the brain stem and cortex, and
C-34
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parenchymal cell degeneration of the liver (Knobloch and Szendzi-
kowski, 1971). Repeated acrylonitrile administration was also
associated with weight loss, leukocytosis, and functional distur-
bances of liver, kidney, and adrenal cortex (Knobloch and Szendzi-
kowski, 1971; Szabo, et al. 1976). Szabo and Selye (1971a,b)
reported that adrenal apoplexy and necrosis were produced in rats
by administration of a single oral dose of acrylonitrile (100 to
200 mg/kg); 100 percent mortality was observed. The adrenals of
the dead animals showed hemorrhages in the cortex and necrosis in
the inner cortical zones. Acrylonitrile induced-adrenal apoplexy,
and mortality in female rats were both prevented by pretreatment
with phenobarbital and adrencorticotrophic (ACTH) hormones (Szabo
and Selye, 1971b, 1972). Szabo and Selye (1972) also reported that
the adrenal lesion was abolished by potent glucocorticoids, especi-
ally dexametamethason and betamethason. Estradiol prevented adre-
nal apoplexy in approximately half the animals treated with a
single lethal dose of acrylonitrile (Szabo and Selye, 1972). The
mechanism by which these drugs interfered with the acrylonitrile
induced injury is not clear. Nevertheless, structure-activity
relationships exist between ACN and other nitriles and other alkyl
compounds which cause duodenal ulcers and/or adrenal necrosis
(Szabo and Reynolds, 1975).
A two year toxicity and carcinogenicity study with acrylo-
nitrile incorporated in drinking water of rats was conducted by
Quast, et al. (1980).
In this study, male and female Sprague-Dawley rats maintained
for two years on drinking water containing acrylonitrile at 35,
C-35
-------
100, or 300 ppm showed a variety of toxic effects. Increasing con-
centrations of acrylonitrile in the drinking water resulted in
decreased water consumption, decreased food consumption, and de-
creased weight gain, in a dose-related fashion in both male and
female rats.
Periodic hematologic determinations indicated that there was
no evidence of adverse hematologic effects caused by ingestion of
drinking water containing acrylonitrile at the concentration used
in this study.
Periodic urinalyses of male and female rats indicated a treat-
ment-related effect in the urine specific gravity in the 100 and
300 ppm groups. The increase in urine specific gravity indicates
that the kidneys were capable of concentrating the urine, and this
was considered to be an adaptation in physiological function to
compensate for the rats limited daily water consumption.
Clinical chemistry determinations used to evaluate kidney and
liver function revealed that neither organ system was adversely
affected in rats ingesting water containing acrylonitrile.
Clinical evidence of altered nervous system function was noted
in treated rats and usually correlated with the presence of a brain
tumor upon microscopic examination of the tissues. Furthermore,
clinical manifestations of irritability were more readily apparent
in the rats ingesting water containing acrylonitrile. Whether this
apparent irritability was a direct effect of acrylonitrile on the
CNS or a result of stress related to the decreased water and food
consumption could not be ascertained.
C-36
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The necropsy findings and subsequent histopathologic exami-
nations of tissues of male rats revealed a variety of pathologic
alterations which occur with greater or lesser frequency in acrylo-
nitrile-treated than in the respective control group of rats.
Changes of a nontumorous nature in the kidneys of male rats re-
vealed that advanced chronic renal disease, which normally occurs
with increasing frequency in aged rats, was less frequently seen in
the 100 and 300 ppm groups of rats, when compared to the control
group.
Many other organ systems showed a concurrent decrease in the
incidence of those pathologic changes which normally occur as a
result of the advanced chronic renal disease. In general, in the
300 ppm group and less frequently in the 100 and 35 ppm groups,
there was a decreased incidence of degenerative vascular changes in
most organs, decreased uremic mineralization of the stomach,
decreased uremic encephalopathy, decreased parathyroid gland
hyperplasia, decreased lung changes associated with renal disease,
decreased left atrial thrombosis of the heart, decreased severity
of focal myocardial degeneration and fibrosis, and decreased aortic
thickening and mineralization. The incidence of atrophy of the
mediastinal fat was increased in the 300 ppm group, and was due to
the decreased nutritional state of these rats. An increase in
splenic extramedullary hematopoiesis was also observed in the 300
ppm group of rats.
Microscopic lesions which were considered related to acrylo-
nitrile treatment were observed, with statistically significant
increased frequency, in the nonglandular gastric mucosa and the
C-37
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endocardium of the heart. Lesions in the nonglandular gastric
mucosa were characterized by hyperplasia and hyperkeratosis and
were observed more frequently and in a dose-related fashion in the
100 and 300 ppm group of male rats. In the endocardium there was
evidence of an increased incidence of endocardial disease in the
300 ppm group.
Few human studies, other than cancer epidemiology, were found
for U.S. workers. Therefore, the majority of studies cited are
from the foreign literature.
The human threshold of smell to acrylonitrile lies between 8
to 40 mg/m (3.7 to 18.5 ppm), and a quick tolerance is always
developed after repeated inhalation (Fairhall, 1957). A point of
unbearability was reached at 800 to 1,000 mg/m (370 to 460 ppm)
sometime after 70 seconds of exposure (Grahl, 1970). The high
threshold of smell and the high absorptive capacity of environ-
mental objects (such as textiles, wood, food, and grain) to acrylo-
nitrile acts to minimize the perception of acrylonitrile and so
intensify the degree of exposure, and consequently the toxicity.
Goncharova, et al. (1977) reported that examinations of 689
persons engaged in the production of acrylonitrile in the USSR evi-
denced effects of acrylonitrile upon the heart. In their studies
Shirshova, et al. (1975) indicated that workers with long service
records in the acrylonitrile polymer industry showed decreases in
hemoglobin level and a trend to leukopenia and relative lymphocy-
tosis. Stamov, et al. (1976) studied the working environment and
health state of workers involved in the production of polyacrylo-
nitrile fibers (Burgas, Bulgaria) where dimethylformamide was also
C-38
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present. Their studies indicated that in exposed workers there is
a tendency towards diseases of the peripheral nervous system/
stomach, duodenum, and skin.
In an epidemiologic study of health impairment among acrylo-
nitrile workers in Japan, Sakarai and Kusimoto (1972) studied 576
workers exposed over a 10-year period (from 1960 to 1970) to
acrylonitrile in concentrations of 5 to 20 ppm. The cohort was
studied with respect to: (a) age and length of exposure to acrylo-
nitrile, (b) subjective complaints, as well as (c) objective symp-
toms. They found increased incidences of subjective complaints
including headache, fatigue, nausea, and weakness; as well as
clinical symptoms of anemia, jaundice, conjunctivitis, and abnormal
values of specific gravity of whole blood, blood serum and cholin-
esterase values, urobilinogen, bilirubin, urinary protein, and
sugar. These clinical values were found to vary directly with
length of exposure to acrylonitrile and differences were signifi-
cantly different from normals. Sakarai and Kusimoto (1972) con-
cluded that acrylonitrile exposures at these levels caused mild
liver injury and probably a cumulative general toxic effect.
The working conditions and health status of operators engaged
in the production of acrylonitrile were studied by Ostrovskaya, et
al. (1976), where the working area atmosphere was polluted by
acrylonitrile as well as other chemicals. In those workers,
changes in the heart and circulation, blood methemoglobin content,
and increased excretion of glucuronic acid occurred during working
hours.
C-39
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Zotova (1975) in the USSR reported that the concentration of
acrylonitrile in the air of the plant he studied exceeded by 5- to
10-fold the "maximal permissible concentration" (i.e., hygienic
goal; 0.435 mg/m ), and he recommended the enforcement of lower
levels for the compound. He reported the blood of workers in con-
tact with acrylonitrile, when compared with control values, had a
lower content of erythrocytes, leukocytes, hemoglobin, and sulfhy-
dryl groups.
Shustov and Mavrina (1975) reported that medical examination
of 340 workers and clinical studies of the blood and other bio-
logical fluids of 50 workers in polyacrylonitrile production plant
showed symptoms of poisoning in the majority of the workers. They
found that workers complained of headaches, vertigo, fatigue,
insomnia, and skin itching. The clinical studies showed that the
majority of the workers had functional disorders of the central
nervous system, cardiovascular, and hemopoietic systems. The
degree of pathological change increased with years of service in
the plant (Shustov and Mavrina, 1975).
Dovzhanskii (1976a,b), Khromov (1974), and Balda (1975) re-
ported contact allergic dermatitis and changes in immunoglobulin
levels upon direct contact with acrylonitrile and other acrylate
components of synthetic fabrics. Mavrina and Il'ina (1974) re-
ported that students of an industrial training school who came in
contact with acrylates (mainly acrylonitrile) at atmospheric levels
of 0.8 to 1.8 mg/m showed disturbed immunological reactivity and
sensitization. The positive allergic reactions in persons not hav-
ing signs of allergic diseases indicated latent allergy (premorbid
C-40
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phase) developing at various times after contact with acrylo-
nitrile. Because of the considerable sensitivity of young people,
sensitization by these substances can develop within several days
after the start of the training (Mavrina and Il'ina, 1974).
Recently Radimer, et al. (1974) reported four cases in which
toxic epidermal necrosis developed 11 to 21 days after patients
returned to houses fumigated with a 2:1 mixture of carbon tetra-
chloride and acrylonitrile; this mixture was once widely used as a
pesticide in Florida homes (Radimer, et al. 1974). In these cases,
four patients were hospitalized with blisters covering almost the
entire skin surface and mucous membranes. Administration of anti-
biotics, corticosteroids, fluids, and electrolytes produced no
improvement in the three adult female patients. These three
patients died of septic shock and gastrointestinal hemorrhage 3 to
4 weeks after exposure (Radimer et al. 1974). They also reported
that the 10-year-old son of one of these patients developed wide-
spread pruritic eruptions, but survived with topical and parenteral
corticosteroid application. The possibility that carbon tetra-
chloride, rather than acrylonitrile, was the responsible agent for
the observed toxicity cannot be excluded absolutely (Radimer, et
al. 1974). Hardy, et al. (1972) reported an impaired pulmonary
function following a railroad accident in which a crew of four
railroad engineers suffered an intense single exposure to unknown
amounts of acrylonitrile. After the exposure, weakness was the
chief symptom followed by dyspnea on exertion when the workers
returned to normal activity. Pulmonary function testing done seven
C-41
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years after exposure indicated that lung damage was still present
in all four workers and had probably originated at the time of the
accident (Hardy, et al. 1972). Two additional cases of mortality
following acute acrylonitrile exposure have been reported. Both
involved children, one treated with acrylonitrile for scalp lice
and the other sleeping in a room fumigated with acrylonitrile
(Grunske, 1949).
Toxicological studies give no clear insight into the possible
mechanisms of acute and subacute acrylonitrile toxicity. Although
Tarkowski (1968) proposed some evidence favoring a cyanide-mediated
effect, there is also evidence against it (Paulet, et al. 1966).
Earlier reports indicated that cyanide liberation is responsible
for acrylonitrile toxicity (Desgrez, 1911; Wagner-Jauregg, et al.
1948). Mediation of acrylonitrile toxicity by cyanide was con-
sidered because of the following observations noted upon acrylo-
nitrile administration: (a) increased blood and urine thiocyanate
concentration (Mallette, 1943; Wilson, et al. 1948; Lawton, et al.
1943); (b) appearance of free cyanide and cyanomethemoglobin in
blood (Hashimoto and Kanai, 1965; Brieger, et al. 1952); (c) slight
similarities to the toxicity symptoms and histopathologic results
produced by administration of hydrocyanic acid and its salts; (d)
successful use of some cyanide antidotes in treatment of some toxic
symptoms resulting from acrylonitrile administration (Dudley, et
al. 1942; Hashimoto and Kanai, 1965; Levina, 1951; Yoshikawa,
1968) . Other hypotheses have attributed the toxicity of acrylo-
nitrile to the intact molecule (Schwanecke, 1966; Paulet, et al.
1966; Ghiringhelli, 1954; Desgrez, 1911; Graham, 1965; Magos, 1962;
C-42
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Benes and Cerna, 1959). Support for these hypotheses comes from
the following observations: (a) no correlation between acrylo-
nitrile toxicity in guinea pigs or rats with either blood levels of
cyanide ions and cyanomethemoglobin or the amount of thiocyanate
excreted in urine (Ghiringhelli, 1954, 1956; Magos, 1962); (b) no
free cyanide ions detected in the blood of guinea pigs exposed to
acrylonitrile (Dudley and Neal, 1942; Dudley, et al. 1942); (c)
histopathologic aberrations after acrylonitrile exposure not
explicable as cyanide action (Dudley, et al. 1942; Benes and Cerna,
1959); (d) controversial reports on the action of specific cyanide
antidotes, e.g., hydroxycobalamine, sodium nitrites, and sodium
thiosulfate in treatment of acrylonitrile poisoning (McOmie, 1943;
Ghiringhelli, 1954; Magos, 1962; Hashimoto and Kanai, 1965).
Benes and Cerna (1959) postulated that in acrylonitrile sensi-
tive animal species, quick decomposition of the entire acrylo-
nitrile molecule to cyanide ion takes place and a typical cyanide
toxicity is produced. However, Brieger, et al. (1952) reported
that high SCN/CN ratios were observed in acrylonitrile sensitive
animals.
Paulet, et al. (1966) reported that the toxic action of
acrylonitrile in rabbits and guinea pigs is only partially due to
cyanide liberation. It has been suggested that additional bio-
transformation may contribute partially to acrylonitrile's acute
toxicity (Paulet, et al. 1966; Benes and Cerna, 1959). Desgrez
(1911) in his earlier studies suggested a role for the conjugated
double bond in acrylonitrile toxicity.
C-43
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Szabo, et al. (1980) investigated the pathogenesis of experi-
mental adrenal hemorrhagic necrosis produced by acrylonitrile in
the rat. One dose of this chemical injected intravenously caused
100 percent incidence of adrenal hemorrhage and necrosis in 90 to
120 minutes. Electron microscopy, histochemistry, and light micro-
scopy combined with colloidal carbon labeling suggested an early
damage (30 minutes after administration of acrylonitrile) to the
vascular endothelium in the adrenal cortex, prominent at 60 min-
utes, when lesion to the parenchymal cells was not visible. The
use of extracellular diffusion tracer horseradish peroxidase fur-
ther indicated that parenchymal cell injury was a late event. Dam-
age to the vascular endothelium in the adrenal cortex was asso-
ciated with retrograde embolization of medullary cells and cell
fragments into the cortical capillaries. The ultrastructurally
demonstrated platelet aggregation and fibrin precipitation at the
sites of discontinuous vascular endothelium were accompanied by a
decrease in circulating platelets and fibrinogen as well as pro-
longation of prothrombin, partial thromboplastin, and thrombin
time. The concentration of dopamine, unlike that of noradrenaline,
in the adrenals but not in the brain of rats injected with acrylo-
nitrile showed a time-dependent elevation. Pretreatment with phe-
noxybenzamine (c^-adrenergic antagonist) or labetalol (ff<- andx*^~
adrenergic blocker) or metyrapone (11-^^-hydroxylase inhibitor)
and the depletion of catecholamines by reserpine or prior medul-
lectomy prevented the chemically induced adrenal necrosis. These
results indicate that the presence of a functional adrenal cortex
is necessary for the development of cortical damage which is asso-
C-44
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elated with early vascular lesions caused and/or modulated by vaso-
constrictive amines from the medulla and/or (metabolites of)
acrylonitrile.
A number of other hypotheses have been developed to describe
the mechanism of acrylonitrile toxicity (Hashimoto and Kanai, 1965;
Ghiringhelli, 1954; Magos, 1962). They suggest the blocking by
cyanoethylation of important sulfhydryl group containing enzymes.
This hypothesis was supported by the excellent antidotal action of
cysteine and glutathione in guinea pigs and mice (Paulet, 1966;
McLaughlin, et al. 1976). A general blocking effect upon cell
metabolism together with irreversible inhibition of the respiratory
enzymes have also been described as possible mechanisms of acrylo-
nitrile toxicity (Ghiringhelli, 1954, 1956). Acrylonitrile is
known to deplete hepatic glutathione (Szabo, 1977) . Dinu (1975)
suggested that a decrease in hepatic glutathione levels renders the
glutathione peroxidase ineffective, and the resulting increase in
the peroxide levels damages the hepatic cells.
Synergism and/or Antagonism
Standard antidotes against cyanide poisoning have been used in
attempts to abate the acute toxicity of acrylonitrile. Dudley and
Neal (1942) found that neither sodium thiosulfate nor methylene
blue afforded any protection against acrylonitrile lethality, while
injection of sodium nitrite had a protective and antidotal action
against the severity of symptoms (particularly the respiratory dis-
tress) and the lethality if given immediately before or after
acrylonitrile exposure. This protective and antidotal action was
C-45
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observed for dogs, rats, and rabbits but not for guinea pigs.
Ghiringhelli (1954) found that guinea pigs were not protected
against acrylonitrile toxicity by the anticyanide treatments
tested: glucose, sodium thiosulfate, and nitrite. Using another
antidote for cyanide poisoning, hydroxycobalamin, Graham (1965)
found that prior treatment of mice or dogs reduced the immediate
(two hours) lethality of acrylonitrile but increased the lethality
at 24 hours. McLaughlin, et al. (1976) found that the combination
of sodium nitrite with sodium thiosulfate was not effective against
acrylonitrile lethality for mice, dogs, and rats and only moder-
ately effective in rabbits, while sodium thiosulfate alone was very
effective rats and less effective for rabbits. Cysteine hydro
chloride was the most effective of all antidotes against acrylo-
nitrile lethality in all species tested by McLaughlin, et al.
(1976).
Other kinds of treatments have been reported to affect the
acute toxicity of acrylonitrile. Jaeger, et al. (1974) reported
that acrylonitrile1s LC^g for fasted rats was approximately three
times lower than that for fed rats (150 vs 425 ppm x 4 hours) .
Szabo and Selye (1972) reported phenobarbital pretreatment dimin-
ished the acute adrenal apoplexy caused by acrylonitrile, and
Paulet, et al. (1966) reported the same treatment delayed its
lethality. HCN and CO were found to enhance acrylonitrile toxicity
in experimental animals (Yamamoto, 1976) as well as in workers
engaged in the acrylonitrile production (Ostrovskaya, et al.
1976) .
C-46
-------
Teratogenicity
Murray, et al. (1976) reported that their studies on Sprague-
Dawley rats demonstrated a potential for acrylonitrile to cause
fetal malformation when it was given to pregnant rats by gavage at
high dose levels (65 mg/kg/day or approaching the LD^Q) on gesta-
tional days 6 to 15. Though sialodacryoadenovirus infection
(murine mumps) occurred in both experimental and control animals,
it is unlikely that this had an effect on the teratogenicity find-
ings. At administration of 65 mg acrylonitrile/kg/day Murray, et
al. (1976) found significant maternal toxicity and increased fetal
malformations, including acaudea, short-tail, short trunk, missing
vertebrae, and right-sided aortic arch (Tables 5 and 6) . Other
signs of embryo toxicity or fetotoxicity at this dose level were
decreased fetal body weight and crown-rump length and increased
incidences of minor skeletal variants. At the time of Cesarean
section, observations were made which are included in Table 7. The
apparent pregnancy rate, i.e., the proportion of bred rats with
visible implantation sites at the time of Cesarean section was
significantly lower among rats given 65 mg acrylonitrile/kg/day
than among the control rats. Administration of acrylonitrile had
no significant effect on the litter size, the fetal sex ratio or
the incidence or distribution of resorptions. At 65 mg/kg/day, the
fetal body and crown-rump length were significantly lower than con-
trol values. No statistically significant effect was observed at
the doses 10 and 25 mg/kg/day.
In Table 5 the incidence of external or soft tissue altera-
tions among litters of rats given various doses of acrylonitrile by
gavage is indicated. At 65 mg/kg/day the frequency of acaudate
C-47
-------
TABLE 5
Incidence of Petal Alterations Observed During the External or Soft Tissue Examination Among
Litters of Rats Receiving Acrylonitrile by Gavage*
Dose Level of Acryloni tr ile, mg/k.g/daya
External Examination
Soft Tissue Examination
External Examination
Acaudate
Acaudate or
short tail
Short trunk
Imperforate anus
Soft Tissue Examination
Right-sided aortic
arch
Ovaries, anteriorly
displaced
Hissing kidney,
unilateral
Dilated renal pelvis,
unilateral
Dilated ureter,
left
Fb
F
L
F
L
F
L
P
L
F
L
F
L
F
L
F
I.
0
443/38
154/38
0
0.2(1»
3(1)
0
0
0
0
0
0
0
0
1(1)
3(1)
0
0
0
0
10
No. Fetuses/No
388/35
135/35
t Affected
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
25
. Litters Examined
312/29
111/29
(no. affected)
0.6(2)
0.6(2)
7(2)
0
0
0
0
1(1)
3(1)
l(l)d
3d)
0
0
2(2)
7(2)
1(1)
3(1)
65
212/17
71/17
2(4)c
4(8)c
35(6)
l(3)c,d
18(3)
l(2)d
12(2)
l(Dd
6(1)
KDd
6(1)
KDd
6(1)
0
0
KDd
6(1)
C-48
-------
TABLE 5 (Continued)
•Source: Murrary. et al. 1976.
aActylonitrile was given by gavage on days 6-15 of gestation.
bF = fetuses; L = litters.
°Significantly different from control by a modified Wilcoxon test, p«c0.05.
This alteration occurred only in fetuses with a short or missing tail at this dose level.
C-49
-------
TABLE 6
Incidence of Skeletal Alterations Among Litters of Rats Receiving Actylonitrile by Gavage*
Dose Level of Actyloni tr ile, mg/kg/daya
Skeletal Examination
Skull Bone Examination
Skeletal Examination
Vertebrae - 12
thoracic and 5 Fb
lumbar (normal no. L
is 13 T and 6 L)
-missing vertebrae
other than 1 F
thoracic and lc L
lumbarc
-missing centra
of cervical F
vertebrae (other
than Cj and C2) L
Ribs -missing 13th
pair only F
L
-missing more
than 1 F
pair9 L
0
443/38
289/37
2(7)
3(1)
0.2(l)d
3(1)
5(23)
29(11)
2(7)
3d)
0
0
10
No. Fetuses/No
388/35
253/34
% Affected
0
0
0
0
8(30)
46(6)
0
0
0
0
25
. Litters Examined
312/29
201/24
(no. affected)
2(7)
7(2)
0.6(2)d
7(2)
10(31)
46(13)
2(7)
7(2)
K2)d
7(2)
65
212/17
141/17
0
0
4(8)d'e
35(6)
34(71)e
88(15)
0
0
2(4)d'e
24(4)
C-50
-------
TABLE 6 (Continued)
Sternebcae -
delated ossifi-
cation, 5th
-missing, Sth
-split, Sth
-split, 2nd
Skull Bone Examination
-delayed ossifi-
cation any skull
bone
F
L
F
L
F
L
F
L
F
L
2(9)
16(6)
0
0
1(4)
10(4)
0
0
7(21)
30(11)
3(13)
23(8)
0
0
1(3)
9(3)
0
0
6(15)
26(9)
4(13)
34(10)
1(2)
7(2)
1(3)
10(3)
0
0
6(12)
29(7)
15(31)e
59(10)
1(2)
12(2)
4(8)
30(5)
2(4)e
24(4)
4(5)
18(3)
*Source: Murrary, et al. 1976.
aAcrylonitrile was given by gavage on days 6-15 of gestation.
bF - fetuses; L - litters.
°The actual number of thoracic, lumbar and sacral vertebrae of each of the affected fetuses were as
follows (normal no. is 13 T, 6 L, 4 S): Control - 12T, 2L, OS; 25 mg/kg/day - 2T, OL, OS, 2T, 1L,
IS; 65 mg/kg/day -13T, 3L, OS; 3T, OL, )S; 13T,
OL, OS; 13T, 5L, 4S.
6L, 2S; 7T, 3L, OS; 13T, 3L, OS; 2T, OL, OS; 3T,
This alteration occurred only among fetuses with short or missing tail at this dose level.
eSignificantly different from control by a modified Hilcoxon test, p«c0.05.
This alteration occurred only among fetuses with 12 thoracic and 5 lumbar vertebrae.
9'1'he affected fetuses exhibited 0-7 pairs of ribs (normal no. is 13).
C-51
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TABLE 7
Observations Hade at the Time of Cesarean Section of Rats Receiving Actylonitrile by Gavage*
Number of bred females
Number of deaths/no, of females
Apparent pregnancy rate
Total pregnancy ratee
Proportion of pregnant animals
detected only byf
sulficie staining
Number of litters
Implantation sites/dam^'
Live fetuses/litter9'**
Resorptions/li tter9'h
% Implantations resorbed
Litters with resorptions
Litters totally resorbed"
Resorpt ions/li ttgrs
with resorptions
Sex ratio, M:F
n
Fetal body weight, g
Fetal crown-rump length, mm1
Dose
0
43
0/43
88% (38/43)
88% (38/43)
(0/38)
38
12 + 3
12 + 3
0 . 7+0 . 9
6% (26/469)
47% (18/38)
0
1.4(26/18)
49:51
5.68+0.28
44.4+1.0
Level of Acrylonitr
10
39
0/39
90% (35/39)
90% (35/39)
(0/35)
35
12 + 3
11 + 3
0.6+0.8
5% (21/409)
40% (14/35)
0
1.5(21/14)
49:51
5.78(0.25
44.5+1.3
lie, mg/kg/daya
25
33
0/33
89% (29/33)
89% (29/33)
(0/29)
29
11+4
11 + 4
0.4+0.6
3% (11/323)
34% (10/29)
0
1.1 (11/10)
48:52
5.80+0.33
45.0+1.2
65
29
1/29
69% (20/29)C>d
83% (24/29)
17% (4/24)d
18
12 + 3
12 + 3
0.6+0.7
4% (10/222)
44% (8/18)
1
1.2(10/8)
53:47
5. 26^0. 32^
43. 6+1. 2^
C-52
-------
TABLE 7 (Continued)
LEGEND
aActylonitrile was given by gavage on days 6-15 of gestation.
No. of females with visible implantation sites at the time of cesarean section or necropsy/total no. of bred
females.
CA female which delivered her litter on day 20 of gestation was included in the calculation of the pregnancy
rates. The litter was not examined for fetal alterations.
Significantly different from control by Fisher's exact probability test, p-<0.05.
eNo. of females with implantation sites as observed either visually at the time of cesarean section or after
staining the uterus with sodium sulfide stain/total no. of bred females.
No. of females with implantation sites detected only after staining the uterus with sodium sulfide stain/total
no. of females with implantation sites.
9Mean + S.D.
Data from the four females in which implantation sites were detected only after sodium sulfide staining of the
uterus were not included in these calculations.
'Mean of litter means + S.D.
'significantly different from control mean by Dunnett's test, p 0.05.
•Sources Hurrary, et al. 1976.
C-53
-------
fetuses among litters was significantly higher than the control
incidence. Also at this dose level, a statistically significant
increase in the combined incidence of acaudate and short-tailed
fetuses was observed. There were no statistically significant dif-
ferences in the frequency of either of these tail anomalies alone
or combined among litters of rats given the lower doses levels (10
or 25 mg/kg/day).
The soft tissue examination indicated right-side aortic arch
in single fetuses at both 25 and 65 mg/kg/day (see Table 5).
The incidence of skeletal alterations among litters of rats
given acrylonitrile by gavage is summarized in Table 6. The inci-
dence of skeletal alterations among litters of rats receiving 10 or
25 mg acrylonitrile/kg/day were not significantly different from
control litters. At 65 mg/kg/day, a significant increase was seen
in the frequency of fetuses missing vertebra(e) other than a single
thoracic and single lumbar vertebra. Also at this dose, each acau-
date or short-tailed fetus (and only these fetuses) had this de-
fect, ranging in severity from missing a single lumbar vertebra to
missing 12 thoracic, all lumbar, and all sacral vertebra. In addi-
tion, the incidence of fetuses missing more than one pair of ribs
was significantly higher than control litters (see Table 6).
An additional study by Murray, et al. (1978) concluded that
when Sprague-Dawley rats were exposed to 0, 40, or 80 ppm of
acrylonitrile by inhalation, teratogenic effects in the offspring
of pregnant rats were suggested at 80 ppm but not 40 ppm. Signifi-
cant maternal toxicity was found at both 80 and 40 ppm.
C-54
-------
A three-generation reproduction study of rats receiving
acrylonitrile in drinking water conducted by Litton Bionetics, Inc.
was conducted to evaluate the effect of acrylonitrile on the repro-
ductive capacity of rats (Beliles, et al. 1980).
The reproductive indices are summarized in Table 8. It should
be noted that the F3b viability index at 100 ppm, while statisti-
cally significant, was higher than the control. Further analysis
by the Mantel-Haenszel method combining Chi-square analysis showed
a significant decrease in both the viability and lactation indices
for the high dose group (500 ppm) . Upon review, the single in-
stance in which the viability index of the 100 ppm group was sig-
nificantly lower than the control, (Fib) was not judged to consti-
tute a meaningful effect.
The histopathologic evaluation of the adult females revealed a
high frequency of unusual tumor types (Table 9). In conclusion,
the results of this three-generation study suggest that:
1. Acrylonitrile at 500 ppm reduced body weight gain and food
intake of the first generation parent rats (FO);
2. The pup survival at the 500 ppm treatment level for both
matings of the first generation was reduced. Further
analysis indicated the viability and lactation indices
were reduced at the 500 ppm level throughout the entire
study. Fostering the pups onto untreated mothers lessened
mortality of the pups, suggesting a maternal effect.
There was no remarkable change on the reproductive capac-
ity at 100 ppm;
C-55
-------
TABLE 8
Summary of Reproductive Indices*
Male Fertility
Mating
Fla
Fib
F2a
F2b
F3a
F3b
Treatment
0
100
500
0
100
500
0
100
500
0
100
500
0
100
500
0
100
500
Ratio
10/10
8/10
10/10
10/10
10/10
13/15
5/10
7/10
8/10
6/10
5/10
8/10
6/10
9/10
10/10
9/10
10/10
10/10
Percent
100
80
100
100
100
87
50
70
80
60
50
80
60
90
100
90
100
100
Female
Ratio
18/20
16/20
16/20
16/20
17/20
22/28
10/20
11/20
14/20
10/20
8/20
14/20
14/20
13/20
15/20
14/20
15/20
17/20
Fertility
Percent
90
90
80
80
85
79
50
55
70
50
40
70
70
65
75
70
75
85
Gestation
Ratio
18/18
16/16
16/16
16/16
17/17
22/22
10/10
11/11
14/14
10/10
8/8
14/14
14/14
13/13
15/15
14/14
13/13
17/17
Percent
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
100
Viability
Ratio
185/186
197/201
166/177**
186/186
182/202**
99/109**
107/109
116/124
133/140
101/101
93/97
138/138
161/161
157/158
157/166**
170/176
198/198**
170/180
Percen
94
98
94
100
90
91
98
94
95
100
96
100
100
99
95
97
100
94
Lact_at io>n
Ratio Percent
138/50
139/150
95/143**
137/150
132/139
87/99
91/91
95/104**
107/114**
82/82
70/73
123/123
128/131
124/124
134/135
106/108
117/119
115/125
92
93
66
91
95
88
100
91
94
100
96
100
98
100
99
98
98
92
*Source: Beliles, et al. 1980.
5 14).
C-56
-------
TABLE 9
Astrocytoma and Zymbal's Gland Incidence
Generation
FO
Fib
F2b
Total
Astrocytoma/Rat
Dose (ppm)
0/19
0/20
0/20
0/59
100
1/20
1/19
1/19
3/59
500
2/25
4/17*
1/20
7/62'
Generation
FO
Fib
F2b
Total
Zymbal's Gland Tumor/Rat
Dose (ppm)
0/19
0/20
0/20
0/59
100
0/20
2/19
0/20
2/59
500
1/25
4/17*
3/20
8/62'
*Source: Beliles, et al. 1980.
**p<.0.05.
C-57
-------
3. In all three generations, the body weights of the 500 ppm
treatment level were reduced on day 21 for both matings
(Table 10);
4. Upon gross and microscopic evaluation, no adverse findings
were observed in the tissues of third generation weanlings
(F3b);
5. No effect on the sciatic nerve was evident among the adult
female rats held for 20 weeks after weaning of the second
litter;
6. A dose-related tumorigenic effect of acrylonitrile in the
drinking water in female rats held 20 weeks after the
weaning of the second litter was suggested by the gross
observations; and
7. Histopathologic evaluation of these dams showed an in-
crease in astrocytomas and Zymbal's gland tumors
(Table 10).
Mutagenicity
The mutagenicity of acrylonitrile to various organisms has
been described by several investigators. Benes and Sram (1969)
noted only weak effects in Drosophila melanogaster and concluded
that acrylonitrile toxicity towards the species limited the test-
ing. Milvy and Wolff, (1977) reported that in various strains of
Salmonella typhimurium activated by mouse liver homogenate, acrylo-
nitrile is mutagenic in the TA 1535 tester strain that is sensitive
to base substitution, as well as strains TA 1538 and TA 1978, which
are sensitive to frameshift mutagens. No dose-response data were
obtained, however, and high reversion rates were seen in the
C-58
-------
TABLE 10
Effect of Acrylonitrile Treatment on Pup Weights
Generation
Fla
Fib
F2a
F2b
F3a
F3b
Dose Level
(ppm)
0
100
500
0
100
500
0
100
500
0
100
500
0
100
500
0
100
500
Mean
Day 4
11
10
9*
10
9
10
11
10
9*
11
10
9
10
9
8*
10
10
8*
Pup Weight (g)
Day 21
42
40
28*
38
35
34*
39
39
30*
51
46
30*
43
43
30*
49
46
32*
*Source: Beliles, et al. 1980
**p<0.05.
C-59
-------
controls. Milvy and Wolff reported that the presence of the acti-
vating system and NADPH cofactor is a prerequisite for acrylo-
nitrile-induced mutagenesis (Milvy and Wolff, 1977).
In a comprehensive study Venitt, et al. (1977) concluded that
acrylonitrile is a mutagen for Escherichia coli strains WP2, WP2
yvrA, and WP2 urvApolA. Acrylonitrile caused a slight dose-related
increase in the number of revertant colonies compared with un-
treated bacteria in 3 of the 4 strains. WP2 lexA was not detectably
reverted by acrylonitrile. Of the three strains showing a statis-
tically significant mutagenic response, WP2 was slightly more
sensitive to the mutagenic effect of acrylonitrile, showing a four-
fold increase over the spontaneous levels compared with a threefold
increase for WP2 uvrA and a twofold increase for WP2 uvrApolA.
Doses above 150 umol per plate caused a decline in mutagenic
response, concomitant with increasing toxicity as shown by a dose-
related reduction in the density of the bacterial lawn. An impor-
tant observation reported by Venitt, et al. (1977) was that the
addition of a metabolizing system in vitro (S-9 mixture prepared
from the liver of Arocloi® 1254-induced CB hooded male rats) had no
detectable effect on the mutagenic action of acrylonitrile. There-
fore, they concluded that acrylonitrile is a directly acting muta-
gen in these strains of E. coli.
The differential response of the tested strains to the muta-
genic action of acrylonitile suggests that acrylonitrile causes
nonexcisable DNA damage (Venitt, et al. 1977; Green, 1976).
Acrylonitrile has been shown to cyanoethylate ring nitrogen atoms
of certain minor tRNA nucleosides and ribothymidine and thymidine
C-60
-------
(Ofengand, 1967, 1971). Accordingly, Venitt, et al. (1977) sug-
gested that acrylonitrile might react with thymine residues in DNA.
Carcinogenicity
A 2-year toxicity and carcinogencity study with acrylonitrile
incorporated in drinking water of rats was conducted by Quast, et
al. (1980).
In this study, male and female Sprague-Dawley rats maintained
for two years on drinking water containing acrylonitrile at 35,
100, or 300 ppm showed a variety of toxic effects. Increasing con-
centrations of acrylonitrile in the drinking water resulted in
decreased water consumption, decreased food consumption, and de-
creased weight gain, in a dose-related fashion in both male and
female rats.
Monthly examination and palpation of the rats was performed to
evaluate the presence of detectable masses indicative of tumor for-
mation. Tumors found in these examinations suggested that after 12
months an increased number of rats in the high dose group had ear
canal gland (Zymbal's gland) tumors or subcutaneous tumors in the
mammary region. These observations were initially noted in rats
ingesting the highest dose level of acrylonitrile and were subse-
quently observed in the two lower dose groups also. The ear canal
gland tumors grew progressively larger, ulcerated, bled from their
surface, and caused deviation of the lower jaw.
The total number of primary tumors and number of rats with a
primary tumor found upon microscopic examination of tissues from
male and female rats maintained for two years on drinking water
containing acrylonitrile are summarized in Table 11.
C-61
-------
TABLE 11
Summary of Primary Tumor Incidence*
ppm AN
in Water
0
35
100
300
% of Rats with a Tumor
Male
67/80
37/47
47/48
46/48
= 83
= 78
= 97
= 97
.8
.7
.9
.9
Female
78/80
47/48
48/48
48/48
= 97.5
= 97.9
= 100
= 100
Number of Tumors per
Bearing a Tumor
Male
152/67 =
84/37 =
152/47 =
178/46 =
Rat
Female
2
2
3
3
.27
.27
.23
.87
250/78
191/47
217/48
217/48
= 3
= 4
= 4
= 4
.20
.06
.52
.52
*Source: Quast, et al. 1980.
C-62
-------
The data reveal that ingestion of water containing acryloni-
trile statistically significantly increased the incidence of total
tumors in male rats in the 100 and 300 ppm groups. The number of
tumors per rat bearing a tumor appears to be increased in all dose
groups in the females and at the middle and high dose groups in the
males.
Gross observations of tumorous changes which were statisti-
cally significant in treated male rats are presented in Table 12.
The ear canal gland (Zymbal's gland), tongue, nonglandular portion
of the stomach, and brain were recognized as tissues with signifi-
cantly increased number of tumors in the 300 ppm group. In the 100
ppm group the tongue and nonglandular portion of the stomach also
showed a significantly increased tumor incidence. In the 300 ppm
group the incidence of adrenal gland tumors was significantly
decreased.
Histopathologic observations of tumors in the central nervous
system (CNS), pituitary, thyroid, and adrenal glands which were
observed to be statistically significantly different in treated
male rats are summarized in Table 13. A significantly increased
incidence of a CNS tumor, characterized as an astrocytoma, was
observed in rats in all dose groups. In addition, a significantly
increased incidence of a focal or multifocal glial cell prolifera-
tion suggestive of an early tumor of the same cell type was ob-
served in the 35 and 300 ppm groups.
The proliferative process in the CNS was observed most fre-
quently in the cerebral cortex, followed by brain stem in the
region of the cerebellum, and less frequently in the cerebellum and
C-63
-------
TABLE 12
Gross Observations of Tumorous Changes Which Were
Statistically Significant in Male Rats Maintained
for 2 Years on Drinking Water Containing Acrylonitrile*
Dose Level (ppm)
Observation 35 100 300
Integument and Subcutaneous Tissue
Subcutaneous tumor - ear canal (Zymbal's gland) - - Inc.
Tumor or tumor-like proliferation of the tongue - Inc. Inc.
Gastrointestinal Tract
Gastric tumor - nonglandular region, focal papil-
loma <=^2 in tumor - Inc. Inc.
Gastric tumor - nonglandular region, focal papil-
loma >-2 in tumor - Inc. Inc.
Gastric tumor - total number of rats with a pri-
mary tumor involving any part of the stomach - Inc. Inc.
Adrenal Gland
Enlarged unilateral or bilateral, with or without
associated color changes, suggestive of tumor - - Dec.
Nervous System
Brain - focal changes in consistency or color sug-
gestive of primary tumor - - Inc.
*Source: Quast, et al. 1980.
Results are listed on the basis of whether the incidence rate for
each respective observation was statistically significanly in-
creased (Inc.) comparable to the control group (-), or apparently
decreased (Dec.).
Data were analyzed using Fisher's Exact Probability Test.
p<.0.05.
Individual values for these observations as well as those which
were not statistically significantly different are presented
elsewhere.
C-64
-------
TABLE 13
Histopathologic Observations
Summary of Tumors in the Central Nervous System, Pituitary,
Thyroid, and Adrenal Glands which were Statistically
Significant in Male Rats Maintained for 2 Years
on Drinking Water Containing Acrylonitrile*
Dose
ppm in H_o
Number of rats
the time per
necropsied during
iod indicated
0
35
100
300
ppm
ppm
ppm
ppm
Cumulative
Results
80
47
48
48
Nervous System
Number of rats with only a focal or 0 ppm
multifocal glial cell prolifera- 35 ppm
tion suggestive of early tumor in 100 ppm
the central nervous system 300 ppm
Number of rats with only a focal or 0 ppm
or multifocal glial cell tumor 35 ppm
(astrocytoma)/number of rats in 100 ppm
the group 300 ppm
Number of rats with either a focal or 0 ppm
multifocal glial cell proliferation 35 ppm
suggestive of early tumor in the 100 ppm
central nervous system and those 300 ppm
with a focal or multifocal glial
cell tumor (astrocytoma)/number of
rats in the group
Pituitary Gland
Number of rats with a pituitary tumor 0 ppm
(adenoma or carcinoma)/number of 35 ppm
rats in the group 100 ppm
300 ppm
Thyroid Gland
Number of rats with a C-cell tumor 0 ppm
(adenoma or carcinoma)/number of 35 ppm
rats in the group 100 ppm
Adrenal Gland
Number of rats with a pheochromo- 0 ppm
cytoma (benign or malignant)/ 35 ppm
number of rats in the group 300 ppm
0/80
4/47**
3/48
7/48**
1/80
8/47**
19/48**
23/48**
1/80
12/47**
22/48**
30/48**
24/80
6/47d
16/48
5/48d
15/80
4/47
2/48(
39/80
21/47
5/48c
C-65
-------
TABLE 13 (Continued)
*Source: Quast, et al. 1980.
**Statistically significant increase from control when analyzed
using Fisher's Exact Probability Test, p<.0.05. Individual
values for these observations as well as those which were not
statistically significantly are presented elsewhere.
^Apparent decrease from controls, not corrected for early mor-
tality.
C-66
-------
the thoracic spinal cord. In general, the changes of a prolifera-
tive type in the cerebral cortex sections were most frequently
observed in the section obtained from the middle of the cerebral
hemisphere.
The endocrine gland tumors involving the pituitary, thyroid,
and adrenals were all observed with significantly lower frequency
in the 300 ppm group than in the control groups. In addition, the
pituitary gland tumors in the 35 ppm group were also significantly
decreased.
Histopathologic observations of tumors in the tongue, stomach,
and pancreas which were observed to be statistically significant in
treated male rats are summarized in Table 14. There was a statis-
tically significantly increased incidence of squamous cell tumors
of the tongue in the 300 ppm group. In the nonglandular portion of
the stomach there was a statistically significant increase in the
number of rats with a squamous epithelial tumor in the 100 and 300
ppm groups. As was noted on gross examination, there were many
rats with multiple papillomas present in this region of the
stomach. Upon microscopic examination of these stomach tumors some
were found to be papillomas only, others were carcinomas only, and
yet other rats had both papillomas and carcinomas.
Stages of the lesion progressed from hyperplasia and hyper-
keratosis, to papilloma, and ultimately, carcinoma (papillary and
ulcerating) formation, with some overlap in the sequence of lesion
development. Tumors were not found in the stomach in the absence
of either gross or histopathologic changes characterized by hyper-
plasia and hyperkeratosis and mixed with other degenerative and
C-67
-------
TABLE 14
Histopathologic Observations
Summary of Tumors in the Tongue, Stomach, and Pancreas
which were Statistically Significant in Male Rats Maintained
for 2 Years on Drinking Water Containing Acrylonitrile*
Dose
ppm in H90
Cumulative
Results
Number of rats necropsied during the
the time period indicated
Tongue
Number of rats with a tumor of the
squamous epithelium (papilloma or
carcinoma)/number of rats in the
group
Stomach - Nonglandular Portion
Rats with only a squamous cell papil-
loma
Rats with only a squamous cell car-
cinoma
Rats with both a squamous cell papil-
loma and a squamous cell carinoma
in the same rat
Rats with either a squamous cell
papilloma, a squamous cell car-
cinoma or both tumor types present
(total number of rats with a tumor
in the nonglandular portion re-
gardless of type)
Pancreas - Acinar Portion
Pancreatic acinar adenoma (exocrine)
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
80
47
48
48
1/80
2/47
4/48
5/48**
0/0/80
2/2/47
16/13/48**
19/14/48**
0/0/80
0/0/47
8/6/48**
23/14/48**
0/0/80
0/0/47
10/4/48**
32/11/48**
0/0/80
2/2/47
34/23/48**
74/39/48**
0 ppm
35 ppm
100 ppm
300 ppm
13/13/80
4/4/47
8/8/48
1/1/48C
C-68
-------
TABLE 14 (Continued)
*Source: Quast, et al. 1980.
**Statistically significant increase from control when analyzed
using Fisher's Exact Probability Test. p<.0.05.
aData listed as number of this type of tumor/number of rats bear-
ing this type of tumor/number of rats in the group. Individual
values for these observations as well as those which were not
statistically significantly different are presented elsewhere.
Apparent decrease from control, not corrected for early mor-
tality.
C-69
-------
reactive changes. These observations were dose related in severity
at the 100 and 300 ppm groups. There were greater numbers of rats
with a carcinoma in the stomach at the highest dose level
(Table 14) , and they also showed a decreased latency period com-
pared to the lower dose groups. The carcinomas which were present
in the nonglandular stomach were predominantly papillary in type
with only a small proportion of the rats with a carcinoma having
the ulcerating type. Only a single ulcerating carcinoma of the
nonglandular stomach invaded through the wall of the stomach and
extended locally into the mesentery. Pancreatic exocrine adenomas
were significantly decreased in the 300 ppm group and may partially
be due to the earlier mortality of these rats.
Histopathologic observations of tumors in the ear canal gland
(Zymbal's gland) which were statistically significant in treated
rats and tumors in the subcutaneous region, mammary region, and
pinna of the ear which were not statistically significant are sum-
marized in Table 15. The incidence of Zymbal's gland tumors was
statistically significantly increased only at the 300 ppm level
when compared with the respective control group. The tumors in the
subcutaneous tissue, mammary region, and pinna of the ear were not
significantly different in treated and control rats and were sum-
marized in this table for comparative purposes with the female
rats.
Evaluation of the various tumor types present in the large
intestine of treated male rats does not indicate a statistically
significant increase in the incidence of any individual tumor type
when the tumors were evaluated collectively without regard to cell
070
-------
TABLE 15
Histopathologic Observations
Summary of Tumors in the Ear Canal, Subcutaneous Tissue, Mammary
Gland, and Pinna of the Ear which were Statistically
Significant in Male Rats Maintained for 2 Years
on Drinking Water Containing Acrylonitrile*
Dose Cumulative
ppm in 1^0 Results
Number
the
of rats necropsied during
time period indicated
0
35
100
300
ppm
ppm
ppm
ppm
80
47
48
48
Ear Canal Gland (Zymbal's Gland)
Number of rats with a Zymbal's gland
tumor (carcinoma)
Subcutaneous, Mammary, and Pinna
of the Eara/b
Rats with a tumor in the subcu-
taneous region, mammary gland
region, and pinna of the ear
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
3/3/80
4/4/47
3/3/48
16/16/48**
21/19/80
8/7/47
13/13/48
11/10/48
*Source: Quast, et al. 1980.
**Statistically significant increase from control when analyzed
using Fisher's Exact Probability Test. p<0.05.
aData listed as number of this type of tumor/number of rats bear-
ing this type of tumor/number of rats in the group. Individual
values for these observations as well as those which were not
statistically significantly different are presented elsewhere.
No statistically significant differences were noted in this group
of tumors.
C-71
-------
type of origin. The combined number of small intestine tumors of
epithelial type (carcinoma of glandular portion of stomach or du-
odenal junction and the small intestine) in the various groups was
as follows: Control - 3/80; 35 ppm - 7/47; 100 ppm - 2/48; and 300
ppm - 8/48. The values were statistically significant in the 35
and 300 ppm groups when compared to controls. The total number of
tumors, regardless of cell type of origin, in the glandular stomach
or duodenal junction, small intestine, and large intestine of male
rats was as follows: Control - 5/80; 35 ppm - 7/47; 100 ppm -
6/48; and 300 ppm - 9/48.
The necropsy findings and subsequent histopathologic examina-
tion of tissues of female rats revealed a variety of pathologic
alterations which were considered treatment-related, and they were
observed to occur with greater or lesser frequency than in the
respective control group of rats. The frequency of microscopic
findings of nontumorous changes was generally decreased in most
organs at the higher dose levels, and was most probably because of
the early mortality and the less severe degree of chronic renal
disease noted in these rats. Tissues in female rats from the
higher dose levels which were less frequently affected with non-
tumorous pathologic alterations were mammary gland, uterus, kid-
neys, pancreas, liver, adrenal glands, parathyroid glands, cardio-
vascular system, nervous system, and adipose tissue. An increased
incidence of splenic extramedullary hematopoiesis secondary to
hemorrhage associated with ulcerating tumors and increased hepatic
atrophy as a result of the decreased nutritional state was observed
in the 300 ppm group.
C-72
-------
Organ systems in female rats showing a significantly increased
incidence of nontumorous microscopic changes that were interpreted
to be primary effects of ingesting water containing acrylonitrile
were found in the nonglandular gastric mucosa and the CNS. In the
stomach these changes were characterized by hyperplasia and hyper-
keratosis in the nonglandular gastric mucosa and were observed to
be significantly increased in the 100 and 300 ppm groups. In the
brain of the 35 and 100 ppm groups of female rats there was a sig-
nificantly increased incidence of focal gliosis and perivascular
cuffing observed.
Gross pathologic observations of tumorous changes which were
observed to be statistically significant in treated female rats are
presented in Table 16. Based upon the gross observations, a sig-
nificantly increased tumor incidence was observed in the ear canal
gland (Zymbal's gland) at all levels, tongue at 300 ppm, stomach at
100 and 300 ppm, small intestine at 100 ppm, and brain at 300 ppm.
A significant decrease in the tumor incidence of uterine endo-
metrium was observed at 100 and 300 ppm and in the pituitary gland
at all dose levels of acrylonitrile.
Histopathologic observations of tumors in the CNS, pituitary,
thyroid, and adrenal glands which were statistically significant in
treated female rats are presented in Table 17. A significantly
increased incidence of a CNS tumor, characterized as an astrocy-
toma, was observed in rats at all dose levels. In addition, a sig-
nificantly increased incidence of a focal or multifocal glial cell
proliferation suggestive of an early tumor of the same cell type
was observed in the 300 ppm group. The incidence of the CNS tumor
C-73
-------
TABLE 16
Gross Observations of Tumorous Changes which were
Statistically Significant in Female Rats Maintained
for 2 Years on Drinking Water Containing Acrylonitrile*
Dose Level (ppm)
Observation 35 100 300
Integument and Subcutaneous Tissue
Subcutaneous tumor - ear canal (Zymbal's gland) Inc. Inc. Inc.
Tongue
Tumor or tumor - like proliferation of the tongue - - Inc.
Uterus
Endometrial polyp (s) - Dec. Dec.
Gastrointestinal Tract
Gastric tumor - nonglandular region, focal papil-
loma < 2 in tumor - Inc. Inc.
Gastric tumor - nonglandular region, focal papil-
loma >- 2 in tumor - - Inc.
Gastric tumor - total number of rats with a pri-
mary tumor involving any part of the stomach - Inc. Inc.
Small intestine - tumor (s) or diverticulum - Inc.
Nervous System
Pituitary enlarged, suggestive of a tumor Dec. Dec. Dec.
Brain - focal changes in consistency or color sug-
gestive of primary tumor - - Inc.
*Source: Quast, et al. 1980.
Results are listed on the basis of whether the incidence rate for
each respective observation was statistically significantly in-
creased (Inc.) comparable to the control group (-) , or apparently
decreased (Dec. ) .
Data were analyzed using Fisher's Exact Probability Test.
Individual values for these observations as well as those which
were not statistically significantly different are presented
elsewhere.
C-74
-------
TABLE 17
Histopathologic Observations
Summary of Tumors in the Central Nervous System, Pituitary,
Thyroid, and Adrenal Glands which were Statistically
Significant in Female Rats Maintained for 2 Years
on Drinking Water Containing Acrylonitrile*
Dose
ppm in H2O
Cumulative
Results
Number of rats necropsied during
the time period indicated
Nervous System
Number of rats with only a focal or
multifocal glial cell prolifera-
tion suggestive of early tumor in
the central nervous system
Number of rats with only a focal or
or multifocal glial cell tumor
(astrocytoma)/number of rats in
the group
Number of rats with either a focal or
multifocal glial cell proliferation
suggestive of early tumor in the
central nervous system and those
with a focal or multifocal glial
cell tumor (astrocytoma)/number of
rats in the group
Pituitary Gland
Number of rats with a pituitary tumor
(adenoma or carcinoma)/number of
rats in the group
Thyroid Gland
Number of rats with a C-cell tumor
(adenoma or carcinoma)/number of
rats in the group
Adrenal Gland
Number of rats with a pheochromo-
cytoma (benign or malignant)/
number of rats in the group
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
0 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
80
48
48
48
0/80
3/48
3/48
7/48**
1/80
18/48**
22/48**
24/48**
1/80
21/48**
25/48**
31/48**
44/80,
13/48°
12/48°
l/48d
22/80
7/48,
4/48
l/48(
17/80
3/48,
1/48
0/48C
C-75
-------
TABLE 17 (Continued)
*Source: Quast, et al. 1980.
**Statistically significant increase from control when analyzed
using Fisher's Exact Probability Test, p<.0.05. Individual
values for these observations as well as those which were not
statistically significantly are presented elsewhere.
Apparent decrease from controls, not corrected for early mor-
tality.
C-76
-------
was higher in female rats (Table 17) than in male rats (see
Table 13) in each of the treatment groups. This observation was
not inconsistent with that anticipated in view of the higher level
of exposure (mg acrylonitrile/kg/day) of females than males.
The endocrine gland tumors involving the pituitary, thyroid,
and adrenal glands were all observed at significantly lower fre-
quency in the 100 and 300 ppm groups, as well as in the pituitary
gland in the 35 ppm group. The decreased incidence of pituitary
tumors in all dose groups was anticipated based on the gross obser-
vations.
Histopathologic observations of tumors in the tongue, stomach,
small intestine and ear canal gland which were observed to be sta-
tistically significant in treated female rats are presented in
Table 18. All of these organ systems showed a significantly
increased tumor incidence in the 300 ppm groups. In addition,
tumors were significantly increased in the nonglandular portion of
the stomach in the 100 ppm group and in the ear canal gland (Zym-
bal's gland) in the 35 and 100 ppm groups. These tumors were
identical to those previously indicated in the male rats.
Tumors involving mammary glands, subcutaneous tissue, skin,
and pinna of the ear which were statistically significant in
treated female rats are summarized in Table 19. In the evaluation
of the female mammary gland tumors it was noted that 10/48 rats in
the 300 ppm group had only a malignant tumor present (excludes rats
with a benign mammary tumor only, as well as those rats which had
C-77
-------
TABLE 18
Histopathologic Observations
Summary of Tumors in the Tongue, Stomach, Small Intestine,
and Ear Canal which were Statistically Significant in Female Rats
Maintained for 2 Years on Drinking Water Containing Acrylonitrile*
Dose
ppm in H-O
Cumulative
Results
Number of rats necropsied during the
the time period indicated
Tongue
Number of rats with a tumor of the
quamous epithelium (papilloma or
carcinoma)/number of rats in the
group
Stomach - Nonglandular Portion3
Rats with only a squamous cell papil-
loma
Rats with only a squamous cell car-
cinoma
Rats with both a squamous cell papil-
loma and a squamous cell carinoma
in the same rat
Rats with either a squamous cell
papilloma, a squamous cell car-
cinoma or both tumor types present
(total number of rats with a tumor
in the nonglandular portion re-
gardless of type)
Small Intestine
Mucinous cystadenocarcinoma of small
intestine without metastasis (adeno-
matus diverticulum type)
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
80
48
48
48
0/80
1/48
2/48
12/48**
1/1/80
1/1/48
12/12/48**
25/18/48**
0/0/80
0/0/48
0/0/48**
1/1/48**
0/0/80
0/0/48
0/0/48**
30/11/48**
1/1/80
1/1/48
12/12/48**
56/30/48**
0 ppm
35 ppm
100 ppm
300 ppm
0/0/80
1/1/48
4/4/48c
4/4/48**
C-78
-------
TABLE 18 (Continued)
Dose
ppm in H-O
Cumulative
Results
Ear Canal Gland (Zymbal's Gland)
Number of rats with a Zymbal's gland
tumor (carcinoma)
0 ppm
35 ppm
100 ppm
300 ppm
1/1/80
5/5/48**
9/8/48**
18/18/48**
*Source: Quast, et al. 1980.
**Statistically significant increase from control when analyzed
using Fisher's Exact Probability Test. p-cO.05.
aData listed as number of this type of tumor/number of rats bear-
ing this type of tumor/number of rats in the group. Individual
values for these observations as well as those which were not
statistically significantly different are presented elsewhere.
°Data not statistically analyzed because fewer sections of small
intestine were examined at this dose level.
C-79
-------
TABLE 19
Summary of Tumors in the Mammary Gland, Subcutaneous Tissue,
Skin, and Pinna of the Ear which were Statistically
Significant in Female Rats Maintained for 2 Years
on Drinking Water Containing Acrylonitrile*
Dose
ppm in H20
Number
the
of rats necropsied during
time period indicated
0
35
100
300
ppm
ppm
ppm
ppm
Cumulative
Results
80
48
48
48
Mammary Gland
Number of rats with only a benign mam-
mary gland tumor (fibroademona/adeno-
fibroma or adenoma)
Number of rats with only a malignant
mammary gland tumor (carcinoma with
or without metastasis)
Number of rats with a benign and a
malignant gland tumor in the same
rat
Number of rats with a mammary gland
tumor (benign only, malignant only,
and both benign and malignant)
Subcutaneous, Skin, or Pinna of the
Eara'b
Rats with a tumor in the subcutaneous
region (other than mammary gland),
skin, and pinna of the ear
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
0 ppm
35 ppm
100 ppm
300 ppm
91/52/80
96/35/48
85/33/48,
48/22/48°
1/1/80
2/1/48
3/3/48
11/10/48**
15/5/80
18/6/48
25/6/48
8/3/48
107/58/80
116/42/48**
113/42/48**
67/35/48
6/6/80
2/2/48
3/3/48
2/2/48
C-80
-------
TABLE 19 (Continued)
*Source: Quast, et al. 1980.
**Statistically significant increase from control when analyzed
using Fisher's Exact Probability Test. p<.0.05.
aData listed as number of this type of tumor/number of rats bear-
ing this type of tumor/number of rats in the group. Individual
values for these observations as well as those which were not
statistically significantly different are presented elsewhere.
No statistically significant differences were noted in this group
of tumors.
Apparent decrease from control, not corrected for early mor-
tality.
C-81
-------
both a benign and a malignant mammary tumor). This increased inci-
dence in the 300 ppm group was statistically significant when com-
pared to controls.
From Table 19, if the number of rats observed in each of the
groups bearing a malignant mammary gland tumor is totaled, whether
it was the only mammary tumor present or was also present with a
benign tumor, the following results are obtained: Control - 6/80;
35 ppm - 7/48; 100 ppm - 9/48; and at 300 ppm - 13/48. The inci-
dence of the rats bearing a malignant mammary gland tumor (when
combined in this fashion) was also statistically significantly
increased at the 300 ppm level. The mammary tumor incidence in the
300 ppm group was significantly decreased if only those rats with a
benign mammary tumor were considered. The total number of female
rats with a mammary tumor present, regardless of type, was signifi-
cantly increased in the 35 and 100 ppm groups, and not different in
the 300 ppm group, when compared to controls. Even though more
rats in the treated groups contained a malignant mammary gland
tumor, and even though they occurred earlier when compared with the
controls, there was no evidence of increased metastatic activity as
an expression of their malignancy.
In general, the occurence of the benign and the malignant mam-
mary tumors in the treated female rats showed a dose-related de-
crease in latency period with increasing concentrations of acrylo-
nitrile in the water. Other tumors of nonmammary origin in the
subcutaneous region of the skin and involving the pinna of the ear
did not show a tumorigenic response in the female rats. It was
interesting to note that male rats also did not show a tumorigenic
C-82
-------
effect in the subcutaneous tissue, pinna of the ear, and the mam-
mary gland (see Table 15). Therefore, the oncogenic response of
mammary tissue in females was biologically quite different than
that observed in males. The findings in female rat mammary tissue
suggest that the response of this hormonally sensitive organ may
have been significantly modified by the presence of acrylonitrile
in the water acting through altered responses of the various endo-
crine glands.
The tumors of the reproductive tract involving uterus, cervix,
or vagina are summarized in Table 20. There was a statistically
significant decreased incidence in the uterine endometrial polyp(s)
at the 300 ppm level. There was no evidence for a significant
increase in any tumor type seen in the female reproductive tract at
any treatment level.
Evaluation of the tumor data for the large intestine of female
rats reveals that no primary tumors were present in the control or
any treated groups. In the small intestine there was the following
combined total number of tumors without regard to cell type of
origin: Control - 1/80; 35 ppm - 1/48; 100 ppm - 4/48; and at 300
ppm - 5/48. The incidence of this tumor was statistically in-
creased only in the 300 ppm group.
The total number of primary tumors and the number of rats with
a primary tumor found upon microscopic examination of tissues from
male and female rats maintained for two years on drinking water
containing acrylonitrile are presented in Table 21.
During the first 18 months of the study, the percent of male
rats with a tumor was considerably increased in the 300 ppm group
C-83
-------
TABLE 20
Histopathologic Observations
Summary of Tumors in the Reproductive System which were
Statistically Significant in Female Rats Maintained for
2 Years on Drinking Water Containing Acrylonitrile*
Dose
ppm in Rj0
Number of rats necropsied during
the time period indicated
Reproductive System
Number of rats with a uterine carcinoma
without metastasis/number of rats in
the group
Number of rats with a uterine carcinoma
with metastasis/number of rats in the
group
Number of rats with a uterine carcinoma
(with or without metastasis) /number
of rats in the group
Number of rats with a uterine sarcoma
(leiomyosarcoma, stromal/ or neuro-
f ibrosarcoma) without metastasis/
number of rats in the group
Number of rats with a uterine sarcoma
(leiomyosarcoma or nuerof ibrosarcoma)
with metastasis/number of rats in the
group
Number of rats with a uterine sarcoma
(leiomyosarcoma, stromal, or neuro-
f ibrosarcoma) with or without metas-
tasis/number of rats in the group
0
35
100
300
0
35
100
300
0
35
100
300
0
35
100
300
0
35
100
300
0
35
100
300
0
35
100
300
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
ppm
Cumulative
Results
80
48
48
48
2/80
0/48
3/48
1/48
1/80
0/48
2/48
0/48
3/80
0/48
5/48
1/48
3/80
2/48
3/48
4/48
0/80
1/48
1/48
2/48
3/80
3/48
4/48
6/48
C-84
-------
TABLE 20 (Continued)
Number of rats with a uterine endo-
metrial polyp
Dose
ppm in 1^0
0 ppm
35 ppm
100 ppm
300 ppm
Cumulative
Results
25/24/80
6/6/48
3/3/48
6/6/48°
*Source: Quast, et al. 1980.
aData listed as number of this type of tumor/number of rats bear-
ing this type of tumor/number of rats in the group. Individual
values for these observations as well as those which were not
statistically significantly different are presented elsewhere.
Apparent decrease from control, not corrected for early mor-
tality.
C-85
-------
TABLE 21
Total Number of Primary Tumors Found Upon Microscopic
Examination of Tissues from Male and Female Rats Maintained
for 2 Years on Drinking Water Containing Acrylonitrile*
i.a
Dose Level and Time Period
Males
Females
Controls
0 to 6 Months
7 to 12 Months
13 to 18 Months
19 to 24 Months
Terminal Kill
Cumulative
0/1/1
6/4/6
39/18/23
80/37/43
27/7/7
152/67/80
0/0/0
1/1/1
18/10/11
159/48/48
72/19/20
250/78/80
35 ppm
0 to 6 Months
7 to 12 Months
13 to 18 Months
19 to 24 Months
Terminal Kill
Cumulative
0/0/0
2/2/2
13/7/14
52/23/26
17/5/5
84/37/47
0/0/0
2/1/1
39/13/13
131/29/30
19/4/4
191/47/48
100 ppm
0 to 6 Months
7 to 12 Months
13 to 18 Months
19 to 24 Months
Terminal Kill
Cumulative
1/1/1
0/0/0
35/15/16
90/26/26
26/5/5
152/47/48
0/0/0
5/3/3
78/20/20
129/24/24
5/1/1
217/48/48
300 ppm
0 to 6 Months
7 to 12 Months
13 to 18 Months
19 to 24 Months
Terminal Kill
Cumulative
0/0/0
4/2/4
84/26/26
90/18/18
0/0/0
178/46/48
1/1/1
30/13/13
118/23/23
68/11/11
0/0/0
217/48/48
*Source: Quast, et al. 1980.
aData listed as number of tumors/number of rats with tumors/number
of rats dying during that time period.
C-86
-------
when compared to the controls. The tumor incidence of male rats in
the 35 ppm and the 100 ppm groups were comparable to the controls
during this period. However, the number of tumors per male rat
bearing a tumor during the first 18 months of the study was in-
creased in rats of the 100 and 300 ppm groups compared to both the
control and the 35 ppm groups.
In the female rats during the first 18 months of the study
there was an increase in the percent of rats with a tumor and in the
number of tumors per rat with a tumor at all treatment levels when
compared to controls. The data indicate that female rats at all
treatment levels showed a greater tumorigenic response and a
shorter latency period for tumor development than did the males
during the first 18 months of the study.
In conclusion, the development of tumors in various organ
systems of male and female rats ingesting water containing acrylo-
nitrile for two years has been demonstrated in this study.
In the intestinal tract of male and female rats, the total
number of tumors in locations other than the nonglandular gastric
mucosa was statistically significantly elevated only in the 300 ppm
group. A carcinoma of the small intestine was the most frequently
observed tumor in the male and female treated rats with an intes-
tinal tumor. There were no tumors in the large intestine of female
rats and those present in males did not show a statistically sig-
nificantly increased incidence.
Tumors of endocrine glands involving the pituitary, thyroid,
and adrenals were usually decreased in both male and female rats at
all treatment levels. In addition, the pancreatic exocrine adeno-
C-87
-------
mas in males at the 300 ppm level and the uterine endometrial polyp
in females at all treatment levels were also decreased in inci-
dence.
In general, the rats ingesting the highest dose level of
acrylonitrile showed the earliest onset and greatest number of
tumors with a larger number of malignant tumors which infrequently
metastasized. Female rats did exhibit a slightly greater toxic and
tumorigenic response than males, and this was concluded to be a
result of the higer dose of acrylonitrile (mg/kg/day) consumed by
the females than the males.
Manifestations of toxicity and tumorigenicity were produced in
this 2-year rat study using high dose levels of acrylonitrile in
the drinking water. A lifetime study conducted in rats using dose
levels of acrylonitrile in their drinking water which they no
longer voluntarily reject would be most useful in placing some
relevant perspective to the toxic and tumorigenic response observed
in rats of this 2-year study. For assessing risk, additional data
are needed for rats receiving lower levels of acrylonitrile in
their drinking water.
It should be noted that Zymbal's gland tumors were also re-
ported in rats during a 3-year reproduction study in rats (Beliles,
et al. 1980; Murray, et al. 1976) (see Teratogenicity section).
In further support of the above data, a letter transmitted by
the Manufacturing Chemists Association dated February 22, 1978
includes a summary of preliminary findings of a study by Dow Chemi-
cal U.S.A. indicating a higher incidence of brain tumors at 80 and
20 ppm in drinking water when compared to historic control data.
C-88
-------
Maltoni, et al. (1977) have recently reported the results of
long-term carcinogenicity bioassays of acrylonitrile, lasting more
than 130 weeks. The monomer has been tested in Sprague-Dawley rats
by inhalation (40, 20, 10, and 5 ppm, 4 hours daily, 5 times weekly
for 52 weeks) and by ingestion (5 mg/kg body weight in olive oil by
stomach tube, once daily, 3 times weekly for 52 weeks). A slight
enhancement of the incidence of some tumors has been reported,
i.e., mammary tumors, fore-stomach papillomas and acanthomas, skin
carcinomas, and encephalic tumors, particularly gliomas.
It should be noted that only one dose was used in the inges-
tion studies, so that no-dose response relationship could be ob-
tained. Data from the inhalation studies are presented on mammary
tumors and Zymbal's gland carcinomas and on encephalic tumors
(particularly gliomas), uterine carcinomas and others (Table 22).
As an additional note it should be pointed out that possible
impurities found in the acrylonitrile used by various investigators
might possibly affect the determination of carcinogenic effect.
The role of these impurities has not yet been determined.
A recent preliminary epidemiological study from E. I. du Pont
de Nemours and Company on its Camden, South Caroline textile fibers
plant showed that persons exposed to acrylonitrile at the plant are
at greater risk of developing cancer, as compared with company,
national and regional experience (O'Berg, 1979). This preliminary
retrospective study analyzes the cancer experience of the cohort of
1,343 workers who were exposed to acrylonitrile between 1950 and
1967. It considers no latency, 15-year latency and 20-year latency
C-89
-------
TABLE 22
Results of Inhalation Study by Maltoni, et al. 1977.
Moura
M.
1
II
III
IV
*
t«l«l
tHUnun
few
40 M*
M If*
10 ».
*.""
Nut
!C»«t»U)
u«» •!« »\
• urtl
•.
I
4
II
ll>
4
14
1
1
1
10
-
10
sss*
t
1
t
M
»l.
II.
1*.
11.
II.
II.
11.
1.
11.
il.J
-
li.i
i.J
10.0
i««r*«*
UUW«
n««
<-tHl
U)
1*.
lit.
IT.
101.
41.
M.
10 J.|
114.0
to 1.1
-
*4.0
lit.*
loo.i
!•••• II*.
•r
twMiin/
••iMl
1.4
1.0
(.)
1.0
.
.
.
.
-
1.0
1.0
1.0-
• Mtl*t|f»<«
NbrM4«M«» M* flfer****
•*.
\
1
1
t
1
II
T
t
-
4
4
« (k|
10.0
ll.l
10.0
(.«
K.I
>l.l
I.I
ll.l
-
ll.l
-
«.*
t**r«4«
U|4Mf
ll«
V
110.1
104.0
110.1
41.0
*l.|
101. 1
114.0
101.1
11.0
-
11.0
-
*I.O
«*»• M.
•1
twwn/
tciut
1.0
1.1
1.0
1.0
1.4
1.0
I.I
•
I.I
1.0
-
1.0
C*r••
««T,
il.O
N.l
11.0
4*.l
-'
»I.O
-
»I.O
H.o
IH.O
IU.1
•w« M*.
•r
ftx?
.0
.1
.0
1.0
-
1.*
.-
1.0
1.0
1.0
1.0
"***»•• f'.»M
ttrcixM**
N.
•
.
-
1
-
1
1
1
1
.
-
i •
•-
-
-
t M
*
.
-
1.1
-
i.<
I.J
I.I
1.1
-
"-
•
-
-
-
lv«n«
UIMi»
IIM
..J.J.I
-
-
-
11
-
n
101. 0
104. •
io).;
-
-
.-
•
-
-
(i) Alive oninulf (fior 2 weeks, wlicn tltc firti lunuHtr (o nummary cirdnonu) WM olucrvctl.
(b) 'llu: |>cici:nlJ0c» tie tcfcrrctt 10 ilw oirrccicd number.
(c) llu: Litmy lime fit mammary luinoiiri i> fiivcn it t,jc; ilic Ijieiicy ilinc of ilic oilter lunwuri it given M pcrM fruin ilic ilorl ot
-------
periods for cancer development. About 36 percent of the 1,343
employees are presently lost to follow-up.
In this study, mortality rates were analyzed for active
employees and retirees, and cancer diagnoses and deaths for active
employees were analyzed using company and national referent rates
to determine expected numbers. The most sensitive analysis, using
du Pont referent rates (correcting for the "healthy worker effect")
and a 20-year induction for cancer (which narrows down the cohort
to 470) indicated eight observed deaths compared with 4.0 expected.
The du Pont Registry data revealed 16 cases of cancer compared to
5.8 expected. The difference was found to be highly significant
(Tables 23 and 24) .
The author of the study notes that the results presented are
preliminary, and that additional follow-up of persons who quit or
were laid off is required. In the cohort, the losses to follow-up
represent a significant percentage (36 percent). About one-third
of the losses have had short-term exposure (less than six months).
The acrylonitrile exposure levels were only qualitatively reported
(on the basis of the job and its potential for exposure) as 3 (low-
est exposure), 2 (moderate exposure) or 1 (highest exposure).
Times at each level were estimated for each cancer mortality.
Excess cancer was observed when considering all sites; individual
sites with excess cancer mortality were lung, large intestine, and
possibly prostate (Tables 23 and 24). The excess cancer in the
cohort is distributed among many anatomical sites although lung and
intestinal cancer predominate. Significant excess overall cancer
mortality cannot be entirely attributable to these primary sites.
091
-------
TABLE 23
Observed and Expected Numbers of Cancer Deaths* for an Acrylonitrile Cohort
with Six Months or Greater Exposure, Based on du Pont Company Rates for 1969-1975,
20-Year Latency**
All sites
Lung
Large Intestine
Prostate
Observed
7
4
2
1
Male Wage
Expected
3.4
1.3
0.2
0.1
Male Salary
P-Value
0.06
0.04
0.02
Observed
1
0
0
0
Expected
0.6
0.2
0.1
.0
*Cancer Registry Entries (active employees only).
**Source: O'Berg, 1979.
C-92
-------
TABLE 24
Observed and Expected Numbers of Cancer Cases* for a Cohort with Six Months
or Greater Exposure, Based on du Pont Company Rates for 1969-1975,
20-Year Latency**
All sites
Lung
Large Intestine
Prostate
Observed
14
5
3
1
Male Wage
Expected
4.9
1.3
0.4
0.3
P-Value
0.0006
0.011
0.008
Male
Observed
2
1
0
0
Salary
Expected
0.9
0.2
0.1
0.1
*Cancer Registry Entries (active employees only).
**Source: Adapted from O'Berg, 1979.
C-93
-------
Because an excess of lung cancer occurs in this cohort, cigarette
smoking must be considered as a possible agent or cofactor; smoking
histories were not available for this interim report however
(O'Berg, 1979) . Another consideration should also be mentioned/-
the du Pont cohort had in common exposure to the following chemi-
cals besides acrylonitrile: dimethylformamide, hydrogen peroxide,
hydroxyanisole, methyl acrylate, phenylether-biphenyl mixture,
sodium metabisulfite, sulfur dioxide, sulfuric acid, and titanium
dioxide {O'Berg, 1977b). A tabulated list of all cancer cases
appear in Table 25 (O'Berg, 1977a).
Monson analyzed the cancer mortality (and morbidity) exper-
ience of 355 white male United Rubber Workers Union members who had
potential exposure to acrylonitrile in the polymerization recovery
and laboratory areas of B.F. Goodrich plant 13, Akron, Ohio
(Table 26) (43 FR 45762). The mortality experience of this cohort
between January 1, 1940 and July 1, 1976 was compared to that of the
U.S. general population. Person-years of follow-up were deter-
mined in 5-year age-time groupings, and expected numbers were cal-
culated by multiplying these person-years by age-time-cause spe-
cific mortality rates for U.S. white males. The cancer registries
for the four Akron area hospitals were reviewed between 1964 and
1974.
Determination was also made of any B]F] Goodrich employee who
developed cancer between these years. In addition, persons who had
cancer as the secondary cause of death on the death certificate
were identified. Based on these data, Monson compared cancer mor-
bidity rates in men who worked in departments with potential expo-
sure to acrylonitrile with unexposed male workers (43 FR 45762) .
C-94
-------
TABLE 25
Cohort Cancer Cases and/or Deaths,* 1969-1975, Duration of Exposure**
Date of Total Years of Exposure
Cancer Site
Lung
Lung
Lung
Lung
Lung
Lung
Large Intestine
Large Intestine
Large Intestine
Prostate
Prostate
Lymphosarcoma
llodgkins
Penis
Thyroid
Nasopharynx
Bladder
Pancreas
First
Exposure
1950
1950
1950
1950
1952
1952
1951
1951
1952
1950
1952
1951
1951
1952
1952
1950
1950
1952
Rounded to Nearest
Whole Year
26
20
7
4
5
4
13
5
5
14
5
1
13
12
14
7
3
6
Time at Severity
(
1 2
18
5
1
5
1
5
5
5
2
3
6
yr.
yr .
yr.
yr.
yr.
yr.
yr.
yr.
yr.
yr-
yr.
8 yr.
1 mo. 1 yr . 4 mo.
2 mo. 1 yr. 2 mo.
1 mo.
2 mo.
3 mo.
8 mo.
8 mo. 1 yr . 8 mo.
1 mo.
20
2
2
3
13
6
13
4
12
11
10
7
3
yt .
mo.
yr. i
yr . 4
yr. i
mo.
yr. 9
mo.
yr. 9
yr.
yr.
yr. 4
mo,
mo,
mo,
mo
mo
mo
*20-year latent period assumed
**Source: O'Berg, 1979.
C-95
-------
TABLE 26
Observed and Expected Deaths for 355 White Male
Union Members Who Ever Worked in Department 5570 - 5579*
ICD No.**
140-205
150-159
153
160-164
177-181
200-205
-
330-334
400-486
470-527
530-581
590-637
800-999
—
Cause of Death
All causes
Malignant neoplasms
Digestive
Large intestine
Respiratory
Genitourinary
Lymphatic & hematopoietic
Residual cancer
Cerebrovascular disease
Circulatory disease
Respiratory disease
Digestive disease
Genitourinary disease
External causes
Residual
Observed
64
20
4
1
9
2
3
2
5
22
5
2
1
5
4
Expected
83.1
15.6
4.6
1.3
5.2
1.7
1.6
2.2
5.1
37.5
4.3
4.5
1.3
8.8
10.5
SMR***
77
128
88
74
175
117
186
94
97
59
117
44
77
57
38
*Source: 43 FR 45762.
**International Classification of Diseases. 7th Revision.
***Standardized Mortality Ratio: 100 x observed/expected.
C-96
-------
According to this study Monson reported that among the male
cohort who had some exposure to acrylonitrile as well as other
chemical exposure in the cohort (such as butadrene), the most sig-
nificant finding was an excess of lung cancer (9 observed, 5.2
expected) (43 FR 45762) . Among lymphatic and hematopoietic cancers
there were 3 deaths where 1.6 were expected. Monson reported that
there were no excess deaths from cancer of the large intestine. He
also reported that the excess of mortality due to cancer from all
sites and of the lung was seen primarily in men who started working
after 1939 and died after 1959 (Table 27) (43 FR 45762). He re-
ported that there were six men identified through the Akron tumor
registries as having cancer; none of these men were known to be
dead as of July 1, 1976. The sites of the cancers of these six men
were; large intestine (1) , kidney (2) , bladder (1) , skin (1) , and
lymphoma (1) . He concluded that an excess of cancer as measured by
mortality or morbidity occurred among men who had exposure to
acrylonitrile. The excess was spread over a number of sites but
was greatest for lung cancer. He indicated that he is unable to
determine whether this excess represents a casual association with
work in those departments in which potential exposure to acryloni-
trile may occur. He also indicated that the study is confounded by
the fact that most of the acrylonitrile exposed workers developing
cancer had worked in other departments where they were potentially
exposed to other chemicals. Finally, Monson concluded that al-
though proof does not exist that the current levels of acryloni-
trile and other chemical exposures (such as butadien) are harmful,
it would be prudent to reduce further exposure to the chemical
C-97
-------
TABLE 27
Observed and Expected Deaths from all Cancers
and Lung Cancer According to Selected Characteristics*
Characteristic
Age started working**
Year started working
Age at death
Year of death
Category
(years)
35
35-44
45
1940
1940-49
1950
65
65
1960
1960-69
1970
All
Obs.
5
5
10
0
12
8
11
9
3
9
8
Cancers
Exp.
4.9
4.7
6.0
0.6
7.9
7.1
11.1
4.5
2.6
6.2
6.8
Lung
Obs.
2
1
6
0
3
6
5
4
0
4
5
Cancer
Exp.
1.2
1.8
1.8
0.2
2.3
2.3
3.5
1.3
0.6
1.9
2.3
*Source: 43 FR 45762.
**Age and year refer to entrance into 5570-5579
C-98
-------
(43 FR 45762) . No quantitative exposures of acrylonitrile are
listed in the report. Monson (43 FR 45762) notes that his data at
Goodrich conflicts with O'Berg's (1979) du Pont study in which an
excess of intestinal cancer was observed. Aside from differences
in other chemical exposures suffered by the two cohorts, Monson did
not assume a 20 year latency period (providing greater sensitivity)
(43 FR 45762), while O'Berg (1979) did.
C-99
-------
CRITERION FORMULATION
Existing Guidelines and Standards
The existing standards for acrylonitrile in various countries
and various years appear in Table 28.
It is evident that at this time, the Russian standard is sub-
stantially less (two orders of magnitude) than the American and
west European standards. The work of Scupakas (1968) indicates,
however, that the standard may be exceeded significantly. The
study of Orusev and Popovski (1973) of a Yugoslavian acrylic fiber
plant indicated that their in-plant concentrations of acrylonitrile
begin to approach the threshold limit value (TLV) in the U.S.
Other investigators have noted that the air standards are often
exceeded (Schwanecke, 1966; Thiede and Franzen, 1965; Babanov,
1960), although it is unlikely that higher concentrations occur
throughout the day.
Almost 20 years ago, it was advocated by Elkins (1959) in the
U.S. that the maximum allowable concentration (MAC) be reduced to
10 ppm (corresponding to that of HCN). According to Babanov (1960)
an acute danger exists even from 0.85 to 6.1 mg/m (0.4 to 2.8 ppm)
in working areas.
In January, 1978, the Occupational Safety and Health Adminis-
tration (OSHA) announced an emergency temporary standard to reduce
sharply worker exposure to acrylonitrile. OSHA director, Dr. Eula
Bingham, directed that, effective immediately, employee exposure to
acrylonitrile must be reduced to 2 ppm averaged over an 8-hour
period [time-weighted average (TWA)]. Dr. Bingham noted that the
Emergency Temporary Standard was necessary because of data from
C-100
-------
TABLE 28
Standards for Arcylonitrile Air Exposure Levels
in Various Countries (between 1970-1974)
Year Country
Air Standard
ppm mg/ro
Kind of
Standard
Reference
1970 USSR
1970 England
1974 U.S.
0.2
20.0
20.0
0.435
1970 Federal Republic 20.0 43.5
of Germany
43.5
43.5
MAC
("Hygenic goal")
MAK
MAC
TLV
Grahl, 1970;
Schwanecke, 1966;
Babanov, 1960;
Pokrokovsky, 1951;
Thiede and Franzen, 1965
Grahl, 1970;
Thiede and Franzen, 1965;
Lefaux, 1966
Grahl, 1970;
Thiede and Franzen, 1965;
Lefaux, 1966
ACGIH, 1974;
Grahl, 1970;
Mallette, 1943;
Dudley and Neal, 1942
C-101
-------
studies of workers previously exposed to acrylonitrile and labora-
tory tests, both of which established "exposure to acrylonitrile
poses a potential carcinogenic risk to humans." While OSHA's posi-
tion is that there is no way to determine a safe level of exposure
to a carcinogen, in this case "a level was chosen to immediately
minimize the hazard to the greatest extent possible within the con-
fines of feasibility" (Anonymous, 1978a).
Current Levels of Exposure
Indices of exposure, apart from very unspecific symptoms (such
as spirographic examination of the lung) in the case of. chronic
exposure (Possner, 1965), include the determination of increased
blood SCN~ level (Mallette, 1943; Wilson, et al. 1948; Lawton, et
al. 1943) and elevated urinary SCN~ level (Mallette, 1943; Sax,
1957; Elkins, 1959; Lawton, et al. 1943).
It must be recognized that smoking presents a problem in
ascertainment of occupational and other exposure because of the
presence of nitriles in cigarette smoke. Thus, smokers may have a
blood level of approximately 3 mg percent SCN~ in blood; the uri-
nary SCN~ level of heavy smokers may normally reach 9 mg KSCN/1 in
contrast to a normal urinary level for nonsmokers of 0.2 mg/1 and
for occasional smokers a normal urinary level of 1.2 mg KSCN/1
(Elkins, 1959). Consequently, in testing for occupational or other
exposure, if it is not known whether a person is a smoker, values of
urinary KSCN 10 mg/1 cannot be considered to result from occupa-
tional exposure. Sax (1957) suggests that it is advisable for the
purposes of screening for exposure to have liver function tests if
C-102
-------
urinary analysis proves to be negative. In addition, another sug-
gested method of screening is that of the spectrophotometric deter-
mination of cyanomethemoglobin in blood (Magos, 1962).
The existing occupational standards have already been men-
tioned. It has also been noted that these standards are often
exceeded in the USSR. The production of significant amounts of
acrylonitrile and HCN from thermal decomposition of polyacryloni-
trile products has already been noted. For example, from the over-
heating of 1 kg of a polyacrylonitrile plastic, about 15 g of HCN
can be formed. Thus, the amount of HCN formed in a 30 m room from
100 to 200 g of polyacrylonitrile fibers corresponds to 10 to 15
times the MAC values (Schwanecke, 1966; Thiede and Franzen, 1965;
Mallette, 1943), and this underlines a special hazard of poly-
acrylonitrile plants. The possible synergism of acrylonitrile and
HCN has already been alluded to.
There are few data on monitoring of ambient air and drinking
water levels of acrylonitrile. A notable exception is the analysis
of in-plant air emission from a propylene-based acrylonitrile manu-
facturing plant by Hughes and Horn (1977). This lack of data pre-
vents us from predicting most actual exposures of the public except
for certain groups at high risk such as occupational workers. At
the present Emergency Air Standard, 2 ppm of acrylonitrile = 4.35
mg/m /day, the acrylonitrile intake of a worker at threshold
level = 0.90 (4.35 mg/m3) (20 m3/day) = 78.3 mg/day, where 0.90 is
the average retention of acrylonitrile (Young, et al. 1977) . Thus,
depending on the half-life of acrylonitrile, a substantial body
burden in occupationally exposed individuals can result.
C-103
-------
As indicated in the Exposure section, some additional environ-
mental monitoring data is becoming available (Midwest Research
Institute, 1977, 1978). However, to date this information is pre-
liminary in nature and conclusions on possible human exposure can-
not be drawn.
Other groups at risk are listed in the next section. Due to a
lack of data, it is impossible to calculate the actual intakes of
acrylonitrile for these groups.
Special Groups at Risk
Shown in Tables 29 and 30 are various groups at varying
degrees of risk to acrylonitrile exposure with attached references
wherever feasible. It should be recalled that NIOSH has estimated
that at least 125,000 individuals are exposed occupationally
(NIOSH, 1977).
Basis and Derivation of Criterion
The animal carcinogenicity studies of Quast, et al. (1980) and
Maltoni, et al. (1977) and the epidemiological studies of O'Berg
(1979) and Monson (1977) were considered to be the most pertinent
data for the determination of a water quality criterion for the
protection of human health. Although the epidemiological studies
showed excesses of various cancers in man, neither study had quan-
titative exposure data of the workers to acrylonitrile and hence
could not be utilized for calculation of a safe level. The cri-
terion was therefore developed from the animal carcinogenicity data
by utilizing a linearized multistage model as discussed in the
Human Health Methodology Appendices to the October 1980 Federal
Register notice, which announced the availability of this document.
C-104
-------
TABLE 29
Occupational Exposure to Acrylonitrile
Occupational
1. Plastic
Acrylonitrile Manufacturers
Polymer Manufacturers
Polymer Molders
Polymer Combustion Workers
Furniture Makers
2. Fabrics
Fiber Manufacturers
Clothing Sewers
3. Biological Product Manufacturing
Dental Polymer Manufacturers
Contact Lens Fabricators
Blood Filter Fabricators
4. Water Treatment and
Manufacturers
5. Pesticide and Fumigant
Manufacturers
Sprayers
Farmers
(NIOSH, 1977)
(NIOSH, 1977)
(NIOSH, 1977)
(Scupakas, 1968)
(Rumberg, 1971;
Duvall and Rubey, 1973)
(Vol'skii, et al. 1973)
(Rapaport, et al. 1974)
(Orusev and Popovski,
1973; Valic and Zuskin,
1977)
(Fedorchuk, 1973)
(Crapper, et al. 1978)
(Stoy, et al. 1976)
(Lindsay, et al. 1977)
(Sato, et al. 1977)
(Radimer, et al. 1974)
(Radimer, et al. 1974)
(Radimer, et al. 1974)
C-105
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TABLE 30
Nonoccupational Exposure to Acrylonitrile
1. Accidental
Exposure to liquid from trans-
portational spill
Combustion and fire (firemen
and domestic personnel)
Ingestion of contaminated water
or food
Respirations of Contaminated Air
(environmental exposure to
acrylonitrile or polyacryloni-
trile plants)
Non-accidental
Cigarette smokers
Wearers of acrylic dentures
Wearers of acrylic underwear,
diapers, and sanitary napkins
Ingestion of food wrapped in
polyacrylonitrile wrapping
Exposure to acrylonitrile
vapors from polyacrylonitrile
furniture
(Hardy, et al. 1972)
(Duvall and Rubey, 1973;
Michal, 1976;
Hilado, et al. 1977)
(Chudy and Crosby, 1978;
Vettorazzi, 1977)
(Izard and Testa, 1968)
(Crapper, et al. 1978)
(Rapoport, et al. 1974;
Harada and Shimodi, 1976)
(Federal Register, 1974,
1975, 1976)
(Vol'skii, et al. 1973)
C-106
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The rat carcinogenicity studies, in general, showed a tumorigenic
response to acrylonitrile whether exposure was by ingestion or
inhalation. These data support the findings of the epidemiological
studies.
Under the Consent Decree in NRDC v. Train, criteria are to
state "recommended maximum permissible concentrations (including
where appropriate, zero) consistent with the protection of aquatic
organisms, human health, and recreational activities." Acryloni-
trile is suspected of being a human carcinogen. Because there is
no recognized safe concentration for a human carcinogen, the recom-
mended concentration of acrylonitrile in water for maximum protec-
tion of human health is zero.
Because attaining a zero concentration level may be infeasible
in some cases and in order to assist the Agency and states in the
possible future development of water quality regulations, the con-
centrations of acrylonitrile corresponding to several incremental
lifetime cancer risk levels have been estimated. A cancer risk
level provides an estimate of the additional incidence of cancer
that may be expected in an exposed population. A risk of 10 for
example, indicates a probability of one additional case of cancer
for every 100,000 people exposed, a risk of 10 indicates one
additional case of cancer for every million people exposed, and so
forth.
In the Federal Register notice of availability of draft am-
bient water quality criteria, EPA stated that it is considering
setting criteria at an interim target risk level of 10~^, 10"^, or
10~ as shown in the following table.
C-107
-------
Risk Levels
Exposure Assumptions Corresponding Criteria '
per day ^=7 IQ^ 10-_5
2 liters of drinking 0.006 yg/1 0.058 yg/1 0.58 yg/1
water and consumption
of 6.5 grams of fish
and shellfish (2)
Consumption of fish 0.065 yg/1 0.65 yg/1 6.5 ug/1
and shellfish only.
(1) Calculated by applying a linearized multistage model as
previously mentioned to the animal bioassay data pre-
sented in the Appendix. Since the extrapolation model is
linear at low doses, the additional lifetime risk is
directly proportional to the water concentration. There-
fore, water concentrations corresponding to other risk
levels can be derived by multiplying or dividing one of
the risk levels and corresponding water concentrations
shown in the table by factors such as 10, 100, 1,000, and
so forth.
(2) Nine percent of the acrylonitrile exposure results from
the consumption of aquatic organisms which exhibit an
average bioconcentration potential of 30-fold. The
remaining 91 percent of the acrylonitrile exposure re-
sults from drinking water.
Concentration levels were derived assuming a lifetime exposure
to various amounts of acrylonitrile (1) occurring from the consump-
tion of both drinking water and aquatic life grown in water con-
taining the corresponding acrylonitrile concentrations and, (2)
occurring solely from the consumption of aquatic life grown in the
waters containing the corresponding acrylonitrile concentrations.
C-108
-------
Because data indicating other sources of exposure and the contribu-
tion to total body burden are inadequate for quantitative use, the
criterion reflects the increment to risks associated with ambient
water exposure only.
C-109
-------
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APPENDIX
Summary and Conclusions Regarding
the Carcinogenicity of Acrylonitrile (AN)*
Acrylonitrile has a molecular structure (CH2=CH-CN) which
resembles that of vinyl chloride (CH2=CH-C1), a chemical known to
cause animal and human cancer. Principally, it is used as an
intermediate in the manufacture of a wide variety of acrylic
fibers, plastics, and in synthetic rubber.
Acrylonitrile is mutagenic in the Ames Salmonella typhimurium
strains TA1535, TA1538, and TA1978 in the presence of mammalian
metabolic activation which indicates both base-pair substitution
and frameshift mechanisms of action. It is also reported weakly
positive in Drosophila.
There is strong preliminary evidence that acrylonitrile is
likely to be a human carcinogen. This conclusion is based on the
following studies: (1) one final and one preliminary report by the
Dow Chemical Co. bioassay of acrylonitrile given in drinking water
to Sprague-Dawley rats; (2) carcinogenicity of acrylonitrile in
Sprague-Dawley rats by Maltoni, administered via inhalation; and
(3) an epidemiologic study by E.I. du Pont de Nemours and Co., Inc.
indicating an excess of lung and colon cancer incidence among
active employees in the company working with acrylonitrile as com-
pared to that of the national experience. In these three studies,
acrylonitrile has induced excess tumor incidence of the central
nervous system as compared to the controls.
This summary has been prepared and approved by the Carcinogens
Assessment Group of U.S. EPA on June 15, 1979.
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In summary, carcinogenic responses have been induced in
Sprague-Dawley rats and humans. These results, together with the
positive mutagenic response, constitute clear evidence that acrylo-
nitrile is likely to be a human carcinogen.
The water quality criterion for acrylonitrile is based on
astrocytoma induction of the central nervous system in female
Sprague-Dawley rats given acrylonitrile via the drinking water, as
observed and reported by the Dow Chemical Co. (Quast, et al. 1980).
It is concluded that the water concentration 'of acrylonitrile
should be less than 0.58 ug/1 in order to keep the lifetime cancer
risk below 10 .
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Summary of Pertinent Data
The water quality criterion for acrylonitrile is derived from
the induction of astrocytomas observed in the central nervous
system of female Sprague-Dawley rats given acrylonitrile in drink-
ing water (Quast, et al. 1980). The criterion is calculated from
the following parameters:
Dose Incidence
(mg/kg/day) (no. responding/no, tested)3
0 0/80
4.36 17/48
10.76 22/48
24.97 24/48
le = 738 days w = 0.314 kg
Le = 738 days R = 30 I/kg
L = 738 days
With these parameters the carcinogenic potency factor for hu-
mans, <3i*' is 0.552 (mg/kg/day)'1. The resulting water concentra-
tion of acrylonitrile calculated to keep the individual risk below
10~5 is 0.58 ug/1.
aThe incidence at the highest dose group was not used in the lin-
earized multistage extrapolation because of lack of fit. See the
Human Health Methodology Appendices to the October 1980 Federal
Register notice which announced the availability of this document
for a complete discussion on the lack of fit of data to the lin-
earized multistage model.
o U. S. GOVERNMENT PRINTING OFFICE : J9RO 7?0-016/«365
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