vvEPA
               United States
               Environmental Protection
               Agency
                Office of Water
                Regulations and Standards
                Criteria and Standards Division
                Washington DC 20460
EPA 440/5-80-075
October 1980
Ambient
Water Quality
Criteria for
Toluene

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     AMBIENT WATER QUALITY CRITERIA FOR

                 TOLUENE
                 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
                              , vaxvy
                        IH30 SfxSa. Dearborn Street
                                     60604

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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.
                                    ii

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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.  al. 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 J. Hansen, ERL-Duluth
U.S. Environmental Protection Agency
Mammalian Toxicology and Human Health Effects:

    James Bruckner (author)
    University of Texas Medical School

    Steven D. Lutkenhoff (doc. mgr.)
    ECAO-Cin
    U.S. Environmental  Protection Agency

    Donna Sivulka, (doc. mgr.) ECAO-Cin
    U.S. Environmental  Protection Agency

    James Lucas, HERL
    U.S. Environmental  Protection Agency

    Albert Munson
    Medical College of  Virginia

    V.M. Sadagopa Ramanujan
    University of Texas Medical Branch
Herbert Cornish
University of Michigan

Daniel Couri
Ohio State University
Patrick Durkin
Syracuse Research Corporation

Myron Mehlman
Mobil Oil Corporation

Richard Peterson
Indiana University School of Medicine

Herbert Schumacher
National Center for Toxicological Res,
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, C. Russom, R. Rubinstein.
                                          IV

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                           TABLE OF CONTENTS

                                                            Page

Criteria Summary

Introduction                                                A-l

Aquatic Life Toxicology                                     B-l
     Introduction                                           B-1
     Effects                                                B-l
          Acute Toxicity                                    B-l
          Chronic Toxicity                                  B-2
          Plant Effects                                     B-2
          Miscellaneous                                     B-3
          Summary                                           B-3
     Criteria                                               B-4
     References                                             B-ll

Mammalian Toxicology and Human Health Effects               C-l
     Exposure                                               C-l
          Ingestion from Water                              C-l
          Ingestion from Food                               C-3
          Inhalation                                        C-5
          Dermal                                             C-7
     Pharmacokinetics                                       C-7
          Absorption                                        C-7
          Distribution                                      C-9
          Metabolism                                        C-ll
          Excretion                                         C-l 3
     Effects                                                C-l5
          Acute,  Subacute, and Chronic Toxicity             C-15
          Synergism and/or Antagonism                       C-37
          Teratogenicity                                    C-39
          Mutagenicity                                      C-41
          Carcinogenicity                                   C-43
     Criterion Formulation                                  C-46
          Existing Guidelines and Standards                 C-46
          Current Levels of Exposure                        C-47
          Special  Groups at Risk                            C-49
          Basis and Derivation of Criteria                  C-49
     References                                             C-52

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                                 CRITERIA  DOCUMENT
                                     TOLUENE
  CRITERIA
                                   Aquatic  Life
      The  available data  for toluene  indicate  that acute  toxicity to  fresh-
 water  aquatic life occurs  at concentrations as  low as 17,500 Mg/l and would
 occur  at  lower  concentrations  among  species  that  are more  sensitive than
 those  tested.   No  data  are  available  concerning the  chronic  toxicity  of
 toluene to sensitive freshwater aquatic life.
     The available data  for  toluene indicate that  acute  and  chronic toxicity
 to saltwater aquatic life occur at  concentrations  as  low as 6,300 .and  5,000
 yg/1, respectively,  and would  occur  at  lower  concentrations  among  species
 that are  more sensitive  than those tested.

                                 Human Health
     For the protection  of human health from  the  toxic  properties of toluene
 ingested  through  water  and contaminated  aquatic  organisms,  the  ambient water
 criterion is  determined to be 14.3 mg/1.
    For the protection  of human  health from  the  toxic  properties of toluene
 ingested  through  contaminated  aquatic organisms  alone, the  ambient  water
criterion  is determined to be 424 mg/1.
                                     VI

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                                 INTRODUCTION

    Toluene is  a clear, colorless,  noncorrosive liquid with  a sweet,  pun-
gent, benzene-like odor.  The production of  toluene  in  the United  States has
increased  steadily  since 1940  when  approximately  31  million  gallons  were
produced;  in  1970,  production  was  694 million  gallons.    Approximately  70
percent of the  toluene  produced is converted to benzene,  another  15 percent
is  used  to produce  chemicals,  and  the remainder is  used as  a  solvent for
paints and as a gasoline additive [National  Institute for  Occupational Safe-
ty  and Health (NIOSH),  1973].
    Toluene  is  produced primarily  from petroleum or petrochemical  processes
(96  percent),   and  on  a  small  scale  from  metallurgical  coke  manufacturing
(Kirk  and Othmer, 1963).   Approximately 70 percent  of the toluene produced
is  converted to benzene, another 15 percent is used  as a  feedstock, 15 per-
cent  is used for  the production of other chemicals  and the balance is used
directly as  a component of  gasoline or as a solvent for paints and  coatings.
The total  annual  discharge  of  toluene to  the  environment by  industry  is
estimated at 691,800 metric tons; 99.3  percent  (686,960 kkg)  is in the form
of atmospheric  emissions   and  0.7 percent  (4,840  kkg) as  a constituent  in
wastewater.
     Toluene,   also  referred  to   as   toluol,  methylbenzene,  methacide,  and
 phenylmethane,  is an aromatic  hydrocarbon which  is  both volatile  and  flamma-
 ble (40 FR 194).  The  molecular  structure  is  distinguished from that  of ben-
 zene by the substitution of a methyl group for one hydrogen atom.
     Toluene  has   the  molecular   formula   C?H8,   a   molecular   weight   of
 92.13 g, a boiling point of  110.625°C,  a  freezing  point of -94.9°C (Stecher,
 1968),  a density  of  0.86694  at 20°C,  a  vapor  pressure  of 30  mm  Hg  at
                                       A-l

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26.03"C, a refractive index of 1.4893  at  24"C  (Kirk  and Othmer,  1963),  and a
log octanol/water  partition  coefficient  of  2.69  (Tute,  1971).   Toluene  is
only slightly  soluble  in water, 534.8 ^  4.9 mg/1  in freshwater  and  379.3 +
2.8 mg/1  in  seawater  (Sutton  and Calder,  1975).   It is miscible with  alco-
hol, chloroform,  ether,  acetone, glacial  acetic acid,  carbon disulfide  and
other organic solvents (Shell  and Ettre,  1971).
    Th.e  nucleus  of  toluene,  like  that   of  benzene, undergoes  substitution
reactions.  Substitution occurs almost exclusively in the  ortho  (2)  and para
(4) positions  and occurs  faster  with toluene  than  with  benzene (Bradsher,
1971).   The  presence  of a methyl  group  offers  additional  possibilities  for
reaction; the most important  is  dealkylation to produce benzene.  Hydrogena-
tion of toluene  takes  place readily to  form methyl-eyelohexane (Kirk  and
Othmer,  1963).   Toluene  may be oxidized  with air in the  presence of manga-
nese or  cobalt naphthenates to form benzoic  acid;  controlled chlorination of
toluene  yields benzol  dichloride  which  may  be hydrolyzed  to  benzaldehyde
(Gait,  1967).   Most  reactions, however,  require specialized  conditions  and
are carried out commercially.
    Although toluene is  a  volatile  compound  and has  been shown to be readily
transferred  from water  surfaces  to  the  atmosphere  under  ideal  conditions
(Mackay  and  Wolkoff, 1973),  its  transport and persistence under environment-
al  conditions  is  not well  known.   In  the atmosphere,   toluene  is subject to
photochemical  degradation  to  benzaldehyde   and  traces  of  peroxybenzoyl  ni-
trate.   It  is  known  also that toluene can  re-enter  the  hydrosphere  in rain
(Walker, 1976).
    Toluene  has been detected  in  municipal  finished  water supplies at  levels
ranging  from 0.1  ug/1  to 11 ug/1.   The toluene metabolites benzaldehyde and
benzoic  acid were also  found in finished water at  concentrations up  to 19
                                      A-2

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                                  REFERENCES

Bradsher,  C.K.   1971.   McGraw-Hill  Encyclopedia  of Science  and Technology.
McGraw-Hill Book Co., New York.

Gait, A.J.  1967.  Heavy Organic Chemicals.  Pergamon Press, Ltd., Oxford.

Kirk, R.E. and  D.  Othmer.   1963.   Kirk-Othmer  Encyclopedia of Chemical Tech-
nology.  2nd ed.  John Wiley and Sons, Inc., New York.

Mackay,  D.  and A.M. Wolkoff.   1973.   Rate of  evaporation  of low-solubility
contaminants  from  water  bodies  to  atmosphere.   Environ.  Sci.  Technol.
7: 611.

National  Institute  for  Occupational Safety and Health.   1973.   Criteria for
a recommended standard...Occupational exposure to toluene.

Shell, F.D.  and L.S.  Ettre (eds.)  1971.   Encyclopedia  of Industrial Chemi-
cal Analysis.   Interscience Publishers, John Wiley and Sons, Inc., New York.

Stecher, P.G.  (ed.)   1968.   The Merck Index.   8th  ed.   Merck and Co., Inc.,
Rahway, New Jersey.

Sutton, C. and  J.A. Calder.   1975.   Solubility of alkylbenzenes in distilled
water and seawater at 25°C.  Jour. Chem. Eng. Data.  20:  320.
                                      A-3

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Tute, M.S.   1971.   Principles  and  practice of  Hansch  analysis: A  guide to
structure-activity  correlaion  for  the medicinal  chemist.  Adv.  Drug  Res.
5: 1.

Walker,   P.   1976.   Air  pollution  assessment  of toluene.   MTR-7215.   Mitre
Corp., McLean, Virginia.
                                      A-4

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Aquatic Life Toxicology*
                                 INTRODUCTION
     Acute toxicity tests  have  been conducted with toluene  and  a  variety of
freshwater fishes and Daphnia magna; the  latter  appears  to  be more resistant
than the  fishes.   All  but one of the  tests  were conducted  using static pro-
cedures with unmeasured concentrations.
     Three  saltwater  fish species  have been  acutely  exposed to  toluene as
have several  invertebrate species.   Results of  these  tests  indicate a range
of  50  percent  effect  concentrations from 3,700 pg/l  for the bay shrimp to
1,050,000  Pg/l  for the Pacific  oyster.  All  of these  tests  were  conducted
using  static  procedures   although  concentrations were  measured  in several
tests.
                                    EFFECTS
Acute  Toxicity
     Daphnia magna is  the only tested  freshwater  invertebrate  species;  and
the 48-hour  ECgo  values  for  this  species  were  60,000  and  313,000  yg/1
 (Table 1).
     The  range  of 96-hour  LC5Q values for  the goldfish,  fathead  minnow,
 guppy, and bluegill  is  12,700 to  59,300 yg/1 (Table  1).
      Potera (1975) conducted  a variety of  24-hour  exposures with  the  grass
 shrimp, Palaemonetes  pugio, using  static procedures with measured concentra-
 tions   (Table 5).   Temperature  (10  and  20°C), salinity (15 and 25  g/kg, and
 life  stage  (larvae and  adults)  were  the  variables  considered.    The  total
 *The  reader  is  referred  to   the  Guidelines  for  Deriving  Water  Quality
 Criteria for the  Protection  of  Aquatic  Life and Its Uses  in  order  to better
 understand  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 toxicity as described  in the Guidelines.
                                       B-l

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range  of  LC50  values  for the  six tests  was  17,200  to 38,100  ug/1  which
relatively small difference indicates that  the  variables  did not have a very
great  effect.   The LCrn  values  for  the  bay  shrimp,  grass  shrimp,  mysid
shrimp, and Pacific oyster range from 3,700 to 1,050,000 yg/1 (Table 1).
     The  96-hour  LC5Q  values  for  the  striped  bass  (Benville  and  Korn,
1977)  and  coho  salmon  (Morrow,  et al.  1975) were  6,300 and  between  10,000
and 50,000 ug/1, respectively  (Tables 1  and 5).   The sheepshead minnow (U.S.
EPA,  1978)  appears to be  much  more   resistant  to  toluene  with  an  LC5Q
between 277,000 and 485,000 ug/1 (Table 5).
Chronic Toxicity
     A  chronic  value  of  5,000  ug/1  (Table 2)  has  been  obtained from  an
embryo-larval test  with the  sheepshead  minnow in which  the  observed adverse
effect  was on  hatching and  survival   (U.S.  EPA,  1978).   The  96-hour  IC™
for  the sheepshead minnow in  the same  study  (U.S.  EPA,  1978)  is between
277,000 and  485,000 yg/1  and  this results  in an  acute-chronic ratio between
55  and  97.  No  chronic data  are  available for  any  saltwater invertebrate
species and toluene, nor for any freshwater species.
     The species mean acute and chronic  values are summarized in Table 3.
Plant Effects
     Two freshwater algal  species have been  exposed to  toluene and the re-
sults  (Table  4) demonstrate that  these  species  are  relatively  insensitive
compared to the fishes.  There  was a 50  percent  reduction in cell  numbers of
the alga, Chlorella vulgaris,  at 245,000 yg/1 (Kauss and Hutchinson,  1975).
     Several   studies  have been  conducted  with  saltwater algal species  and
one has  been  conducted with kelp,  Macrocystis  pyrifera  (Table  4).   Effects
on growth, respiration  and photosynthesis occurred  at  toluene concentrations
                                      B-2

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fro.  3,000  to  greater  than 433,000  „,/!.  The  results are  quite  variable
since these extreme values are for the same species, Skeletonema costatun,.
Miscellaneous
      Wallen et  al.  (1957)  exposed  mosauitofish to toluene in the presence of
high  concentrations  of  suspended  solids  and  calculated   a  96-hour  LC50
value of  1,180,000  ug/1  (Table  5).
      Most of the  data  for  saltwater  species  has  been  discussed.   In  addi-
tion, Potera  (1975) observed narcosis of grass shrimp within  15 minutes dur-
 ing  an exposure  to 19,800 wg/l.  and  obtained 24-hour LC5Q values  of  24,200
 and 74,200 for a saltwater copepod species (Table 5).
 Summary
      Five freshwater species  have been acutely tested with  toluene,  and the
 cladoceran,  Daphnia  magna,  was more  resistant than four fish  species.  The
 EC5Q and  LC50  values  for  all  species  were  in the  range  of   12,700  to
 313,000  ug/1.   The ECgo  values  for  two  algal species  were 245,000 wg/l and
 higher.   No  chronic tests  have  been  conducted  with toluene and  freshwater
 species.
      There   was  a  wide  range  of  EC5Q  and  LC50   values   for  saltwater
  species  of 3,700  vg/l  for  the bay shrimp to  1,050,000  wg/l  for the  Pacific
  oyster.   An embryo-larval test has  been conducted for  the  sheepshead  minnow
  and effects were  observed  at  7,700  wg/l but  not  at  3,200 ug/1.   The  acute-
  chronic  ratio for  this  species  is between  55  and  97.   Several  saltwater
  algal  species  and kelp have  been  tested and effects   were  observed  between
  8,000 and greater than 433,000 Mg/l.   Studies with the grass shrimp resulted
  in  no  observed  effect  of  salinity,  temperature, or  life  stage on acute
  lethality.
                                        B-3

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                                   CRITERIA

     The  available  data   for   toluene   indicate  that  acute  toxicity  to
freshwater  aquatic  life occurs  at concentrations as low  as  17,500 ug/l and
would  occur at  lower  concentrations among  species  that  are  more sensitive
than those  tested.  No  data are  available concerning the chronic toxicity of
toluene to sensitive freshwater aquatic life.
     The available data for toluene  indicate that acute and chronic toxicity
to saltwater aquatic life occur  at concentrations as low  as  6,300 and 5,000
wg/1,  respectively,  and would  occur at  lower concentrations  among  species
that are more sensitive than those tested.
                                     B-4

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                                                          Table 1.  Acute values  for  toluene
                                                                     LC50/EC50     Species Acute
                                                                      (ug/|)        Value (tig/1)
03
 I
Ul
FRESHWATER SPECIES
Cladoceran,
Daphnla magna
Cladoceran,
Daphnla magna
Goldfish,
Carasslus auratus
Goldfish,
Carasslus auratus
Fathead minnow,
Plmephales promelas
Fathead minnow.
Plmephales promelas
Guppy,
Poecllla retlculata
Bluegll 1,
Lepomls macrochlrus
Blueglll,
Lepomls macrochlrus

Pacific oyster.
Crassostrea glgas
Mysld shrimp,
Mysldopsls bah la
Bay shrimp,
Crago franclscorum
Grass shrimp,
Pa 1 aemonetes puglo
S, U 60,000

S, U 313,000

FT, M 22,800

S, U 57,680

S, U 34,270

S, u 42,330

S, U 59,300

S, U 24,000

S, U 12,700

SALTWATER
S, U 1,050,000

S, U 56,300

S, M 3,700

S, U 9,500

-

137,000

-

22,800

-

38,100

59,300

-

17,500

SPECIES
1,050,000

56,300

3,700

9,500

Reference


Brlngman & Kuhn, 1959


U.S. EPA,  1978

Brennlman, et at.  1976
 Pickering 1 Henderson,
 1966

 Pickering i Henderson,
 1966

 Pickering i Henderson,
 1966

 Pickering 4 Henderson,
 1966

 Pickering 4 Henderson,
 1966

 U.S.  EPA,  1978
                                                                                                      LeGore, 1974


                                                                                                      U.S.  EPA,  1978


                                                                                                      Benvllle  and Korn,  1977


                                                                                                      Tatem,  1975

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                              Table 1.   (Continued)



                                                                      LC50/EC50     Species Acute
                              Species                     Method*      (uq>l)       Value  (ug/I)      Reference

                              Striped  bass,                S, M          6,300           6,300        Benvllle  and  Korn,  1977
                              Morone saxatIlls
                               * S =  static, FT = flow-through, U » unmeasured, M = measured


                                No Final Acute Values are calculable since the minimum data  base  requirements  are  not met.
CO
 I
CTi

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                                                 Table 2.  Chronic values for toluene (U.S. EPA, 1978)
                                                                            Method*

                                                                    SALTWATER SPECIES
                                                                                                  Chronic
                                                                                       Limits      Value
                                                Sheepshead minnow,
                                                Cyprlnodon ^arlegatus
                                                * E-L =  embryo-larva I
                                                                    Acute-Chronic Ratio
                                                   Species
                                                                           Chronic
                                                                            Value
                                                                            (ug/D
I
-j
Sheepshead minnow,       5,000
r.yprlnodon varlegatus
         Acute
         Value
         (U9/U

         277,000-
         485,000
E_l_       3,200-      5,000
          7,700
                                               Ratio

                                               55-97

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                                                Table 3.  Species Mean acute and chronic values for toluene
 i
00
Number
5
4
3
2
1
6
5
4
3
2
1
Species
Cladoceran,
Daphnla magna
Guppy,
Poecllla reticulata
Fathead minnow,
Plmep hales promelas
Goldfish,
Carassius auratus
Blueglll,
Lepomls macrochlrus
Pacific oyster,
Crassostrea glgas
Sheepshead minnow,
Cyprlnodon varlegatus
Mysld shrimp,
Mysldopsls bah la
Grass shrimp,
Palaemonetas puglo
Striped bass,
Morone saxatl 1 is
Bay shrimp,
Crago franc Iscorum

Species Mean Species Mean
Acute Value* Chronic Value
(ug/l) (ug/l)
FRESHWATER SPECIES
137,000
59,300
38,100
22,800
17,500
SALTWATER SPECIES
1 ,050,000
277,000- 5,000
465,000
56,300
9,500
6,300
3,700
Acute-Chronic
Ratio**
55r97
                                 * Rank from high concentration to low concentration by species mean acute  value.


                                 **See the Guidelines for derivation of this ratio.

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                                                           Table 4.  Plant  values  for toluene
CO

Species

Effect
••i • ••
Result
(ug/l)

Reference



FRESHWATER SPECIES
Alga,
Chlorel la vulgarls
A 1 — a
Alga,
Sel enastrum capricornutum
A 1 --~
Alga,
Sel enastrum capricornutum
Cel 1 numbers
24-hr EC50
96-hr EC50 for
chlorophy 1 1 _a
production
Ce 1 1 numbers
96-hr EC50
245,000
>433,000

>433,000

Kauss i Hutch Inson,
1975
U.S. EPA, 1978

U.S. EPA, 1978





SALTWATER SPECIES
Kelp,
Macrocystls pyrlfera
A 1 nS4
A iga,
Amphldlnlum carter 1
Alga,
Chlorel la sp
Alga,
Chlorel la sp
A 1 i~isa
Alga,
Cricosphaera carterae
Al a
Puna 1 lei j_a tertlolecta
A 1 na
Alga,
Skeletonema costatum
A 1 na
Aiga,
Skeletonema costatum
A 1 *-is»
Alga,
Skeletonema costatum
Photosynthesis

Growth


Photosynthesis
respiration
Photosynthesis
respiration
Growth


Growth

Growth


96- hr EC50 for
ch lorophy 1 1 j±
production
96- hr EC50 for
reduction in
r-ol 1 numbers
10,000

100,000


34,000
85,000

100,000


100,000

8,000


>433,000

>433,000

Anonymous, 1964

Dunstan, et al.


Potera, 1975
Potera, 1975

Dunstan, et al.


Dunstan, et al.

Dunstan, et al.


U.S. EPA, 1978

U.S. EPA, 1978



1975





1975


1975

1975







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                                                            Table 5.  Other data for toluene
CO
 I
                              Species
                              Mosqultoflsh,
                              Gambusia afflnis
 Copepod,
 Nltocra splnlpes

 Copepod,
 Nltocra splnlpes

 Grass shrimp  (adult),
 Palaemonetes  puglo

 Grass shrimp  (adult),
 Palaemonetes  puglo

 Grass shrimp  (adult),
 Palaemonetes  puglo

 Grass shrimp  (adult),
 Palaemonetes  puglo

 Grass shrimp  (larva),
 Palaemonetes  puglo

 Grass shrimp  (larva),
 Palaemonetes  puglo

 Grass  shrimp,
 Palaemonetes  puglo

 Coho  salmon,
 Oncorhynchus  klsutch

 Sheepshead minnow,
Cyprlnodon varlegatus
96 hrs
24 hrs
24 hrs
24 hrs
24 hrs
24 hrs
24 hrs
24 hrs
24 hrs
15 mlns
96 hrs
96 hrs
FRESHWATER SPECIES
LC50 In
turbid
water
SALTWATER SPECIES
LC50
LC50
LC50
LC50
LC50
LC50
LC50
LC50
Marcos 1 s
LC50
LC50
                                                                Result
                                                                (ug/l)     Reference
                                                              1,180,000    Wai ten,  et a I.  1957
24,200    Potera,  1975


74,200    Potera,  1975


20,200    Potera,  1975


17,200    Potera,  1975


37,600    Potera,  1975


38,100    Potera,  1975


30,600    Potera,  1975


25,800    Potera,  1975


19,800    Potera,  1975
                                                                                             10,000-   Morrow, et al. 1975
                                                                                             50,000

                                                                                           >277,000    U.S. EPA, 1978
                                                                                           <485,000

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                                  REFERENCES

Anonymous.  1964.   An  investigation of the  effects  of discharged wastes  on
kelp.  Calif.  State Water Control Bd., Publ. No. 26:  58.

Benville,  P.E.,  Jr. and  S.  Korn.   1977.  The  acute  toxicity of  six mono-
cyclic  aromatic  crude  oil  components to  striped  bass  (Morone saxatilis) and
bay  shrimp  fCrago franciscorum).  Calif.  Fish and Game.  63: 204.

Brenniman,  6..  et al.   1976.  A continuous flow bioassay method to evaluate
the  effects of  outboard  motor  exhausts  and selected  aromatic  toxicants on
fish.   Water. Res.   10:  165.

Bringman,  G.  and  R.  Kuhn.   1959.   Vergleichende  wasser  - toxikologische
untersuchungen   an  bakterien,   algen   und   kleinkrebsen.    Gesundheits   -
 Ingenieur.  80:  115.

 Ounstan,  W.M.,  et  al.   1975.   Stimulation  and inhibition  of  phytoplankton
 growth by low molecular weight hydrocarbons.  Mar. Biol.  31: 305.

 Kauss,  P.B.   and  T.C.   Hutchinson.   1975.    The  effects  of  water-soluble
 petroleum  components   on   the  growth  of   Chlorella  vulgaris  Beijernck.
 Environ.  Pollut.   9: 157.

 LeGore,  R.S.    1974.   The effect  of  Alaskan  crude  oil  and  selected  hydro-
 carbon  compounds  on embryonic development of the Pacific oyster, Crassostrea
 gigas.   Ph.D.  Dissertation.   Univ.  of  Washington.  190 pp.
                                       B-ll

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 Morrow,  J.E.,  et al.   1975.   Effects  of some  components  of  crude  oil  on
 young coho salmon.   Copeia.  2: 326.

 Pickering, Q.H. and C.  Henderson.   1966.  Acute  toxicity  of some  important
 petrochemicals  to fish.   Jour. Water Pollut. Control  Fed.  38: 1419.

 Potera,  F.T.   1975.   The effects  of  benzene,  toluene and  ethylbenzene on
 several  important members of  the estuarine ecosystem.   Ph.D.  Dissertation.
 Lehigh University.

 Tatem, H.E.   1975.   Toxicity and  physiological' effects  of  oil and petroleum
 hydrocarbons  on estuarine  grass  shrimp  Palaemonetes pugio.  Ph.D.  Disser-
 tation.  Texas A. and M. University.

 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.

Wallen,  I.E.,  et al.   1957.   Toxicity  to  Gambusia  affinis of  certain  pure
chemicals in turbid  waters.  Sewage Ind.  Wastes.   29:  695.
                                     B-12

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Mammalian Toxicology and Human Health Effects
                             EXPOSURE
Ingest ion from Water
     Toluene  has  recently been  identified  in both  raw  water and
finished  water  supplies  of several  communities  in  the  United
States.   Levels of up  to  11 ug/1 were found in November 1974,  in
finished  water  from  the New  Orleans  area  (U.S. EPA,  1975a).   After
the  results  of  the  study were publicized,  a nationwide  survey,  the
National  Organics Reconnaissance Survey (NORS), was  undertaken  to
determine the concentration  of organic chemicals in drinking water.
Ten cities across the country were selected to represent the major
 types of raw water sources.  A  total  of  72 compounds were  identi-
 fied in  the  first five water  supplies  surveyed  (Coleman,  et  al.
 1976).   Toluene was  1  of  18 compounds occurring in more than one-
 half of  the  finished  waters of  the 10 cities  (U.S.  EPA,  1975b).
 Six of the ten water supplies contained  toluene.   Levels of 0.1 and
 0.7 ug/1 were measured in the two water supplies where quantitative
 results  were available.  Benzaldehyde,  a toluene metabolite, was
 identified  in  three  water supplies.   Fifteen ug/1 of benzoic acid,
 a  second  metabolite,  was  found  in another  city's  water.
      A second  nationwide survey of levels of organic chemicals  in
  the Nation's water  supplies, the National Organic Monitoring Survey
  (NOMS),  was  conducted in  three phases in 1976 (U.S. EPA, 1977).   In
  the first phase  of  this survey,  toluene was apparently not included
  in the analytical screen.   Toluene was,  however,  detected  in  1 of
  111 community finished water  supplies during  the second  phase of
                                 C-l

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 the program.   In  the  third and most recent phase, toluene was found
 in one raw water and three finished water supplies  of  11 communi-
 ties surveyed.  A  level  of  19  ug/1 was measured by gas chromato-
 graphy/mass spectrometry  (GC/MS)  in one of  these finished waters,
 while 0.5  pg/1 was  found  in another.  Concentrations of 0.1 and 0.5
 ug/1 of benzaldehyde  were  present  in  the  drinking water of  two
 cities.
      Although  little  information is apparently  available concern-
 ing potential  sources of organics in drinking water,  investigations
 of  the phenomenon are underway (U.S. EPA, 1975b). Suspected sourc-
 es  include  industrial effluents,  spills, discharges  of oil and gas-
 oline  from  boats, municipal waste treatment facilities,  agricultur-
 al  runoff,  and landfills.  Volatile  hydrocarbons  such  as  benzene
 and  toluene would be  expected to evaporate  rapidly  into  the  atmo-
 sphere from bodies  of water.  Mackay and Wolkoff (1973)  calculated
 the  evaporative  half-life for toluene in water to be 30.6  minutes
 at  25 C.  The  half-life for benzene was slightly longer,  37.3 min-
 utes,  although the  vapor  pressure of benzene is about  three  times
 that of toluene.  This  discrepancy  can  be explained by  the higher
water solubility of benzene, 1,780 mg/1, versus 515  mg/1  for  tolu-
ene.   Mackay  and Wolkoff (1973)  point out  that actual rates of
evaporation  in the  environment  may be  substantially reduced  from
these estimates,  due to  insufficient diffusion of organics in water
to  the air-water interface to replace those organics being  lost by
evaporation.   Insufficient diffusion  can be  the result of inade-
quate mixing of the water and absorption/solubilization of  the or-
ganic on or in particulates  and  sediments.   The half-life would
                               C-2

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therefore be expected to be considerably  shorter  for  toluene in a
fast-flowing,  shallow river  than for that  in  a deep lake  or  the
ocean.
Ingestion from
     Very little data on levels of toluene in foods are available.
Apparently this is largely due to the lack of concern  for  toxicity
of the chemical.  Ogata and Miyake  (1973) detected  toluene  in  sea-
water and fish after an offensive odor appeared  in fish caught  from
harbor  waters  in  the  proximity  of petroleum  and  petrochemical
plants  near  Mizushima,  Japan.   Identification of toluene  was  con-
firmed  by gas chromatography,  infrared absorption  spectrometry,
ultraviolet  absorption spectrometry, and  mass  spectrometry.   The
 flesh of one representative fish was found to contain toluene at 5
tfg/g of flesh.  Ogata and Miyake (1973) confirmed that toluene was
 readily taken up  into  the muscle and  liver  of  eels  kept in  tanks
 containing  water  to which either  petroleum industrial  wastes or
 toluene  and other  aromatic  hydrocarbons were  added.   In a  sub-
 sequent publication (Ohmori,  et al.  1975),  the  same group of inves-
 tigators reported that eel liver homogenate was inferior to that of
 rats in the  metabolism of p-nitrotoluene and p-nitrobenzyl alcohol,
 analogues of toluene and  benzyl alcohol.   The  authors  speculated
 that  this metabolic deficit  might  contribute  to accumulation  of

 toluene  in  fish.
       Two of the major metabolites of toluene, benzaldehyde and ben-
  Zoic acid,  are  found in substantial levels in foods.  Benzaldehyde
 occurs as a natural constituent of bitter almond, peach, and apri-
  cot kernel oils  and  is  added intentionally as  a  flavoring  agent.
                                 C-3

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 Benzole acid is used as an antimicrobial agent or food preservative
 (National Academy of  Sciences  (NAS),  1972).   Benzoic acid appears
 to  have  a very large margin  of safety  in animals  and  man  (World
 Health Organization  (WHO),  1974).   It  is  rapidly and effectively
 metabolized and  seems to have  little  potential to  produce  tissue
 injury.  Estimated acceptable  daily intake  in  man is placed at 0 to
 5  mg/kg,  based largely upon an observed no-effect level in rats of
 approximately 500 mg/kg.
      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
lipids for consumed freshwater and estuarine fish and shellfish is
3.0 percent.
     No measured steady-state bioconcentration factor (BCF) is avail-
able for toluene, but the equation "Log BCF =  (0.85 Log P) -  0.70"
                               C-4

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can be used  (Veith,  et al.  1979, to estimate  the  BCF for aquatic
organisms that contain about 7.6 percent lipids 
-------
 atmospheric levels of toluene  in Los Angeles were largely associat-
 ed with motor  vehicle emissions.  Pilar and Graydon (1973) measured
 a maximum level of 188  ppb toluene in Toronto and an average level
 of 30 ppb.  These  values are comparable to those seen several years
 before in Los Angeles by Lonneman, et  al.  (1968).   These investi-
 gators reported a maximal concentration of 129 ppb and  an  average
 concentration  of  37  ppb.   Toluene was the most  abundant aromatic
 hydrocarbon.   Its  concentration was more than twice that of  benzene
 or m-xylene, the next most abundant aromatics.  Comparison of tolu-
 ene:benzene  ratios in the atmosphere with  those  in auto exhausts
 revealed  higher ratios in  the  atmosphere (Lonneman, et  al.  1968;
 Pilar  and Graydon, 1973).   This finding  suggests that a  substantial
 amount of atmospheric toluene  originates from a  source  other  than
 automotive emissions, possibly  from solvent losses.
      Solvents  are  used for a variety of  purposes including chemical
 processing, metal degreasing, dry cleaning, as  thinners/vehicles  in
 chemical  products,  and  as  surface coatings.   The  majority of  sol-
 vents  which are produced eventually evaporate  into the atmosphere,
 either  intentionally or unintentionally (NAS,  1976).  A  relatively
 small  proportion enters water.   In data reviewed  by NAS  (1976) on
estimated solvent  usage in  the  United  States in 1968,  toluene was
 the fifth most extensively utilized solvent,  ranking  behind only
petroleum  naptha  (which  contains  toluene),   tetrachloroethylene,
ethanol, and trichloroethylene.
     As with  most other volatile hydrocarbon  solvents,  the most
significant inhalation exposures  to toluene  occur in occupational
and inhalant abuse settings. Typical industrial exposure environments
                               C-6

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and their associated  exposure  levels  are reviewed by the National
Institute for Occupational Safety and Health (NIOSH, 1973) and are
alluded to as  they  relate  to potential adverse health effects and
pharmacokinetics in the relevant  sections  of  this document.   Sim-
ilarly, injurious effects seen in individuals  who abuse  toluene are
discussed in  the  document.   Inhalant abusers are  unique in that
they repeatedly subject  themselves to extremely high vapor  levels
of toluene and other  volatile  hydrocarbons in order to become in-
ebriated.
Dermal
     Dermal exposures  of  significance are primarily restricted  to
occupational or home use settings.
                         PHARMACOKINETICS
Absorption
     The pharmacokinetics  of toluene  has  been extensively studied
in both human  and  animal  subjects.  The majority of these studies
have involved inhalation exposure  to the chemical.  Astrand,  et al.
(1972) subjected volunteers to toluene vapor at 100 ppm and 200 ppm
and detected  the  compound  in  their  arterial  blood within 10 sec-
onds after initiation of  the exposure. The toluene  concentrations
in the blood  increased rapidly during the  first  few  minutes  of 30-
and 60-minute  toluene inhalation  sessions,  then rose more  slowly
during the  remainder  of  each session.  The average  arterial blood
toluene levels appeared  to approach equilibrium between  20  and  30
minutes of exposure time.   During this relatively stable  phase the
blood levels were about 1 ;ug/ml in persons inhaling 100 ppm toluene
and  2  jig/ml  in  persons  inhaling 200 ppm  toluene  while at rest.
                                C-7

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 Systemic uptake of toluene was doubled by exercise.  Astrand and her
 co-workers (1972) attributed this  increase  in uptake primarily to
 increased  pulmonary  ventilation.   Carlsson  and  Lindqvist (1977)
 similarly observed that systemic uptake of  toluene increased when
 subjects exercised while  inhaling  100 ppm  of the chemical.  Fur-
 thermore, these  investigators  noted that obese  subjects retained
 more toluene than did  their  thinner counterparts.  Average uptake
 of toluene vapors by  exercising subjects was approximately 37 per-
 cent for thin subjects versus 49 percent for obese subjects.
      Relatively little  attention has been devoted to delineation of
 the  pharmacokinetics  of ingested  or  topically  applied  toluene.
 Apparently there are  no  reports involving  oral  administration  of
 toluene  to humans.   Pyykko,  et al.  (1977)  recently  published  the
 results  of a study in which the uptake of  similar quantities  of
 toluene  in rats was compared  upon oral versus inhalation exposure.
 As  would be  anticipated,  the compound  was  absorbed more  rapidly
 from the  lungs  than from  the  gastrointestinal tract.  Peak  toluene
 levels  in most  tissues of the  rat  were observed 15 to  30  minutes
 following a 10-minute inhalation session, but were not seen until 2
 to 3  hours  after gastric  intubation.  It should be noted that  the
 oral dose of  0.1 ml  toluene  was given to fasted animals  in  1.9 ml
 peanut oil.   This volume of  oil  may have  delayed  toluene  absorp-
 tion.  Although peak  blood  and tissue toluene concentrations were
 substantially higher  in the  rats that inhaled the  chemical, these
 levels diminished  rapidly after exposure and, after 2 to 3  hours,
were comparable  to  the peak  levels  seen in  the  orally  dosed ani-
mals.   Toluene  can  be absorbed  through  the  skin,  though to a
                               C-8

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considerably  lesser  degree  than  through  the  lungs or  the gut.
Wahlberg (1976) found  that  2.0 ml  of toluene applied under an  im-
pervious cover to the  shaved backs of guinea pigs merely depressed
body weight gain, while intraperitoneal  injection of  the same vol-
ume  of  chemical killed  each test subject.   Dutkiewicz and Tyras
(1968)  reported the  rate of  percutaneous toluene absorption in  man
to be 14 to 23 mg/cm2/hour.
Distribution
     Toluene  is rapidly taken up from the bloodstream into the var-
 ious body  tissues  according to their llpid content.  The  arterial
 blood  of  human  subjects  inhaling 100   or  200  ppm of  toluene  was
 found   to  contain  significantly more  of the  solvent  than venous
 blood,  indicating  ready  tissue  uptake  (Astrand, et  al.  1972).  Tis-
 sue  uptake of organic solvents  is known to be  dependent primarily
 upon  the   particular  tissue's  blood  perfusion  and  fat  content
 (Astrand,  et al.  1975).   Partition coefficients (tissue:blood) for
 toluene have been determined on the  basis of a  rabbit tissue exper-
 iment  (Sato, et al. 1974).   The partition  coefficient for  adipose
 tissue was 50 times greater than  for other  tissues.  The partition
 coefficient  for  bone marrow  was  approximately 15 times  greater,
 while  that for brain and liver  was roughly  twice the values for
 lung,  kidney,  heart,  and muscle.   Because the brain  is well  per-
 fused  with blood and  contains considerable llpid,   it should rapidly
 and preferentially accumulate  toluene  upon  inhalation  exposure.
 indeed, men  exposed to high concentrations of toluene vapor experi-
 ence central nervous  system (CNS) depression within minutes (Long-
 ley,  et  al.  1967).   As will  be  related  in a  subsequent  section,
                                 C-9

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 subtle CNS effects appear to be one of  the most  sensitive indices
 of  toluene inhalation.
      Ingested  toluene  is  likely to be handled quite differently, in
 that  the  compound is  absorbed  more  slowly  and  must first  pass
 through the liver before reaching the nervous system.  As will be
 discussed  subsequently,  toluene is extensively and rapidly metabo-
 lized  by the liver.  Thus, a dose  of  toluene which is sufficient to
 cause  minimal  CNS effects when  inhaled  will most likely  have  no
 such  effect when ingested  because  insufficient  quantities  will
 reach  the  nervous system.   Unfortunately,  there  have not  been any
 studies  to determine  the  lowest  oral dose  of  toluene which  will
 inhibit CNS function;  nor are there data contrasting CNS  levels of
 toluene immediately after oral and inhalation exposure. Pyykko, et
 al. (1977)  did measure tissue levels  over a period of 15 minutes to
 24  hours  after  oral  and inhalation administration of comparable
 doses.  Higher tissue levels were  present sooner  in the  animals
 that  had  inhaled  the  solvent.    Several hours  after  the  initial
 exposures,  similar toluene levels were seen in both oral  and inha-
 lation  test subjects' tissues.  The adipose tissue was the  slowest
 to  attain  its  maximal toluene concentration,  although it  accumu-
 lated much more  of the compound than any  other  tissue.   Body  fat
 provides an extensive reservoir  for uptake of hydrocarbon  solvents.
This  is  illustrated  by  the  observation  by Bruckner  and   Peterson
 (1976)  that  saturation  of  the liver  and  brain  of  mice  is   not
 reached after  three  hours of inhalation  of toluene concentrations
as high as  4,000 ppm.
                              C-10

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Metabolism
     Toluene is believed to be converted by the mixed  function oxi-
dase (MFO) system to benzyl alcohol,  which  is  subsequently  oxidized
to  benzaldehyde  and benzoic  acid and  conjugated  with glycine  to
form  hippuric  acid.   Ikeda and  Ohtsuji  (1971) demonstrated  that
pretreatment with phenobarbital,  a classic inducer of MFO activity,
resulted  in a  pronounced  increase in urinary  excretion of  hippuric
acid  by  rats given  an  intraperitoneal injection of 1.18 g/kg tolu-
ene.   Blood  levels  of toluene were  depressed  and  the benzoic  acid
concentration  in the blood increased  in the phenobarbitol-pretreat-
ed (induced)  animals.   Ikeda  and Ohtsuji  (1971)  demonstrated  that
 the rates of p-nitrobenzyl alcoholic oxidation and glycine conjuga-
 tion were  not affected  by the  phenobarbital pretreatment.   The
 metabolism of p-nitrotoluene  (an analogue of toluene) to p-nitro-
 benzoic  acid  was markedly enhanced jin vitro  in  liver microsomes
 isolated from these animals.   As might be  expected,  the duration of
 toluene-induced sleeping  time was significantly shorter  in  the  in-
 duced animals.   Koga  and Ohmiya (1978) have  shown that  inhibition
 of MFO  activity  by SKF 525-A or carbon tetrachloride  will  prolong
 toluene-induced  narcosis and enhance  toluene-induced  mortality in
 rats.   These  investigators also found pyrazole  to  have  a  similar
 effect,  which indicates  the  importance of  alcoholic  oxidation in
 the metabolism of  toluene.  The peroxidase/catalase  system may also
 play  a  role  in the metabolic pathway  of  some animals, in light of
  its  recognized  importance in metabolism of ethanol  in certain spe-
  cies.
       Toluene  is  rapidly and  extensively metabolized  to hippuric
  acid in experimental animals.   Smith,  et al.  (1954)  found that  in
                                 C-ll

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 rabbits  given  350  mg/kg  of  toluene  orally,  about 18  percent of the
 dose was eliminated in the expired air as the parent  compound with-
 in  12  hours.   Less than  1  percent  more was exhaled  over  an addi-
 tional 24-hour period.  No  glucuronide  or  sulfate metabolites were
 detected  in  the  urine of these animals.  Work  in the  same labora-
 tory with rabbits given a single oral toluene dose of 275 mg/kg re-
 vealed that  about  74  percent of the total dose  could  be accounted
 for as urinary hippuric  acid within 24 hours of dosing  (El  Masry,
 et al. 1956).  Thus,  the  majority of  toluene  is rapidly  eliminated
 by the rabbit  as  the  unmetabolized  compound in expired  air  and  as
 the glycine conjugate of  benzoic acid  in urine.  Very  little tolu-
 ene metabolite is  excreted  into  the  bile  of  the  rat  (Abou-El-
 Makarem, et al.  1967).  Bray, et al. (1951) suggested that if tolu-
 ene exposure were  so  high  that  the glycine conjugation mechanism
 was overwhelmed,  glucuronide conjugation might then occur.   Bray
 and his  colleagues did demonstrate  glucuronide conjugates  in  the
 urine of rabbits given large doses of benzoic acid.   It seems like-
 ly that should  the  normal metabolic  pathway be  blocked, more of the
 unmetabolized compound would simply be eliminated via exhalation.
 Bakke and Scheline (1970) administered  toluene  at 100  mg/kg  orally
 to rats  and  found  that 0.5  to  1.1 percent  of the  total  dose  was
 converted to p- and o-cresol, with  the  former predominating.   These
metabolites were excreted in  the urine  as glucuronide  and  apparent
 sulfate conjugates.  Small amounts of benzyl alcohol were  also de-
 tected in the rat urine.
     Toluene appears to be metabolized  and eliminated  by humans  in
much the same manner  as   it  is  in  animals.  Ogata,  et al.  (1970)
                               C-12

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subjected humans to 200  ppm toluene vapor for up to seven hours.  It
was found that  68  percent of the estimated  amount  of  solvent ab-
sorbed systemically was recovered  as urinary hippuric acid.  This
metabolite appeared in the urine soon after  initiation  of  the  expo-
sure, an  indication of  rapid metabolism of  toluene  to  this  princi-
pal metabolite.  Nomiyama and Nomiyama  (1974)  similarly observed  a
rapid  increase in  urinary  excretion of  hippuric acid in  men  and
women  inhaling 107 ppm  toluene.   Urinary hippuric acid  excretion
reached  its maximum  in  the  second  hour of 4-hour exposures  and
decreased rapidly upon  cessation  of the exposures.   Furthermore,
Nomiyama and Nomiyama (1974)  found an average of 18 percent of the
 total  amount of toluene absorbed  systemically  by the  subjects was
 eliminated  in expired air.  Urinary  metabolites other  than  hippuric
 acid have not been reported in the literature.  Thus, it would ap-
 pear that humans metabolize toluene  much  the same as other  species,
 in both a qualitative  and quantitative sense.
 Excretion
      Toluene  is rapidly excreted  from  the  body.  Most of a dose  of
 toluene  can be accounted for within the  first  12 hours as  the  par-
 ent compound  in expired air and as hippuric acid in the urine.  Upon
 termination of  inhalation  sessions,  toluene levels in the  alveolar
 air and  blood of  human  subjects drop rapidly (Astrand, et al. 1972;
 Nomiyama and  Nomiyama,  1974; Sato,  et  al.   1974;  Carlsson  and
 Lindqvist,  1977).   Sato,  et  al.  (1974),   after  analyzing toluene
 desaturation data in humans, concluded that the  initial rapid phase
 of elimination was governed primarily by the rate of alveolar ven-
  tilation,  the rate  of  toluene metabolic clearance,  and  the blood/
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 air  partition coefficient of  toluene.   A slower  elimination rate
 for  females than males was observed.   This  was attributed  to  the
 larger  proportion  of  fatty  tissue  in  females.    in  view  of  the
 greater  uptake of  toluene seen  in  obese subjects,  Carlsson  and
 Lindqvist  (1977)  noted that  on  prolonged toluene  exposure,  these
 individuals will accumulate more of the compound and will eliminate
 it more slowly,  thereby subjecting their  tissues  to higher concen-
 trations for  longer periods.
     Studies  involving elimination of toluene  in  animals  reveal  a
 pattern of  toluene elimination similar  to  that  seen in man.   It is
 possible  in animal studies  to  monitor levels  of  the chemical  in
 various bodily tissues which cannot be measured in man.   Desatura-
 tion occurs more slowly in adipose tissue  than  in  any other  tissue
 of the  rat (Pyykko, et al.  1977; Carlsson  and Lindqvist,  1977).
 Interestingly, elimination of toluene from the  bone marrow is also
 relatively  slow, apparently  the  result of the  lipoidal  nature of
 the marrow.   Toluene  is lost quite rapidly  from  the  brain, as  is
 reflected  physiologically  by rapid  recovery from CNS   depression
 (Peterson  and Bruckner,  1976;  Savolainen,  1978).   Peterson  and
Bruckner (1976), while  setting  up an animal model of human  self-
 intoxication with toluene,  found  it necessary to re-expose mice  and
 rats to concentrated toluene  vapors at  intervals  of 10  to 20 min-
utes in order to maintain an intoxicated state  in  the animals.
     Measurement of hippuric acid excretion  in  the urine has been
advocated  as an index of the  severity of occupational  toluene expo-
sure.   Ogata,  et al.  (1970-),  while evaluating  human  subjects ex-
posed   to  vapor  levels  of 200  ppm,  stated  that   the quantity  of
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hippuric acid excreted  in the urine was proportional to total toluene
exposure (i.e., exposure time  X vapor concentration).  Other groups
of investigators, however, have observed wide  interpersonal varia-
tion in  hippuric  acid  excretion,  even  among  control subjects  not
exposed  to  toluene  (Ikeda  and  Ohtsuji,  1969; Engstrom,  et  al.
1976).   Friborska (1973) found marked variations in  the  same  indi-
viduals  from day to day. Diet is  undoubtedly a major source of this
variation  because many foods  contain hippuric  acid  precursors such
as benzaldehyde and benzoic acid.  Analysis of hippuric acid levels
in urine is  probably of more  value  as  a qualitative index of  high-
level  toluene  exposure than as a precise quantitative index, parti-
cularly  at low exposure levels  (Engstrom,  et al.  1976).
                              EFFECTS
Acute, Subacute,  and  Chronic Toxicity
      The  primary  hazard  associated  with  acute  exposure  to  high
 levels of toluene is  excessive CNS depression.  The 8-hour LC5Q in
mice was  5,300 ppm  (Svirbely,  et al.   1943).   In  contrast, the 8-
 hour LC5Q for benzene was 10,400 ppm.   Kojima  and Kobayashi  (1973)
 found 20,000 ppm toluene  to  be lethal  to  rats after 30  to 50  min-
 utes.  Death was attributed  to CNS depression.  Average  concentra-
 tions of  toluene in the tissues  of the  animals that  succumbed  were
 as  follows:   blood -  330  ug/g;  liver  - 700 ug/g; and  brain - 890
 ug/g.  Wolf, et al.  (1956) calculated  the  oral LD5Q for  young adult
 rats  to be  7  g/kg.  Kimura,  et al.  (1971)  published  a  similar  oral
 LD5Q  of 6.4 ml/kg for young adult rats. These latter investigators
 found newborn  and  14-day-old  rats  to be  much  more  susceptible
 to  toluene poisoning than  adults.   The  LD5Qs  were  1 ml/kg for
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the newborns  and  3 ml/kg for the  14-day-old  animals.   Kimura, et



al. (1971)  stated that  the  lowest dose at  which gross  signs of



poisoning characterized  by  CNS  depression were  seen  in the young



adult rats was 2 ml/kg.  They divided  this dose level by a safety



factor of 1,000 to derive a value  of 2  jul/kg,  which they  felt was a



reasonable maximum permissible  solvent  residue limit  for  single



oral exposures.



     A number  of  episodes  of acute  overexposure to  toluene vapor



have been reported in the medical  literature.   Lurie  (1949)  and



Reisin, et al.  (1975)  published  accounts of workers  who were  ren-



dered  unconscious by fumes  of the  chemical.  Longley, et  al. (1967)



related the details of two episodes in which  a number of men  were



quickly affected upon  inhalation  of  an estimated 10,000 to 30,000



ppm toluene.   Effects  ranged  from  exhilaration and light-headedness



to dizziness  and  unconsciousness.   Recovery  was quite  rapid, as



would  be predicted, since the compound  is so rapidly mobilized  from



the brain (Savolainen, 1978)  and eliminated from the body.  Little



clinical  evidence  of  tissue injury was seen  in  these patients.



Nomiyama and Nomiyama  (1978) have recently reported  several fatal



cases  involving purposeful self-intoxication with toluene.  In one



instance, four  persons were  apparently  narcotized while sniffing



pure toluene  in a  car.   Toluene  is probably the most popular  of a



variety of volatile  hydrocarbons which  are  inhaled  intentionally



for their euphoric or  intoxicating effects (Press and Done, 1967;



Natl.   Inst.  Drug Abuse, 1977).    Toluene  "sniffing"  is a rather



unique situation  in  that the participant  repeatedly  inhales  high



vapor   concentrations   in order  to  maintain  a  desired  state of
                               C-16

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altered consciousness.  This  practice  may be continued for years,
and thus affords toxicologists an opportunity to observe consequen-
ces of  both acute  and  chronic  high-level  toluene  exposure.   The
situation is often  complicated by the  participant's use of commer-
cial  products  which consist of  complex mixtures of chemicals.   In
such  cases  it is difficult to attribute toxicity to  any single com-

ponent.
      With  the  increase in popularity  of  "glue  sniffing,"  a  situa-
 tion  known  as  "sudden sniffing death" has  been brought  to  the at-
 tention of  the  medical  community.  Bass  (1970) published an account
 of the sudden, unexpected deaths of 110  solvent  abusers.   Toluene
 was  implicated in a number of these cases.  The deaths did not ap-
 pear to be  due to suffocation or CNS depression,  but  rather to sud-
 den  cardiovascular collapse at light plane anesthesia levels. Bass
 speculated that  cardiac  arrhythmias may have  resulted from  a com-
 bined  action of  solvent,  stress or physical activity,  and hypoxia.
 Winek,  et  al.  (1968)  also published an account of such a  fatality
  involving  toluene.  Chenoweth  (1946) was apparently  the first  to
  demonstrate  in the laboratory that toluene and  a variety of other
  volatile hydrocarbons  could sensitize the heart  to catecholamines.
  By injecting  epinephrine intravenously he was able  to  induce car-
  diac  arrhythmias  in dogs  inhaling  various  hydrocarbon  solvents.
  Taylor and Harris  (1970)  reported a slowed  sinoatrial  rate, pro-
  longed P-R interval,  and sensitization to asphyxia-induced atrio-
  ventricular block  in mice  subjected  to either toluene or toluene-
  based  airplane  glue fumes.  On the basis  of  these findings,  it  was
  suggested  that  the  "sudden  death"  syndrome  in  humans   may  be
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attributed  to  any  one  or  combination  of  the  following:  sinus
bradycardia,  atrioventricular  block,  or  ventricular  fibrilla-
tion/failure.   Taylor  and  Harris  (1970)  pointed out that not only
will  the  stress and  asphyxia often associated  with solvent abuse
contribute  to cardiac  arrhythmias,  but that hydrocarbons may have
direct toxic effects on  the  heart.   Electrocardiogram analysis of
rats  inhaling toluene  has  been reported  to reveal adverse effects
such  as disorders of repolarization  and  arrhythmias (Bereznyi, et
al. 1975; Morvai, et al. 1976).  The latter group of investigators
found the effects of benzene  to be much more intense.  It should be
emphasized here that all of the aforementioned cardiotoxic effects
have  been seen  in humans and  laboratory  animals subjected  to very
high  vapor  concentrations  of  toluene.   It would  appear unlikely
that  low-level  inhalation or oral toluene exposure would be detri-
mental to  the  cardiovascular  system.    Ogata,  et  al.  (1970)  did
report an apparent decrease in pulse rate but no significant alter-
ation of blood  pressure in human volunteers inhaling 200 ppm tolu-
ene.  No  significant effect  on heart  rate was observed  in other
persons  inhaling  100 to 700  ppm  toluene  (Astrand, et  al.   1972;
Gamberale and Hultengren, 1972).
      Inhalation of relatively low concentrations of toluene may be
somewhat irritating  to mucus  membranes and produce  a decrement in
psychophysiological  functions.  Several  studies involving inhala-
tion  exposure of  human  subjects have  been  conducted  to determine
the lowest vapor level  which  will produce subjective complaints and
objective evidence  of  CNS depression.   Results of  these  studies
form  the basis  for  the  NIOSH (1973)  recommendation of 100 ppm for
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occupational toluene exposure.   Subjective complaints such as fa-
tigue, dizziness,  headache,  weakness,  and  throat and eye irritation
were made by subjects breathing  toluene concentrations of  200 ppm.
More objective measurements of CNS effects by Ogata, et al.  (1970)
and by Gamberale and Hultengren (1972) also suggest that  the  "mini-
mum  effect  (vapor) level"  is about  200  ppm.   Ogata  and his co-
workers  (1970) found a prolongation of eye-to-hand reaction time  in
persons  inhaling  200  ppm toluene but no effect on flicker fusion.
Gamberale  and  Hultengren (1972)  noted  that inhalation of 300 ppm
for  20 minutes by their subjects increased reaction time,  while 700
ppm  of  the  compound was required  to  diminish perceptual  speed.
inhalation of 100 ppm toluene for 20 minutes had no apparent effect
on either  index.    These  investigators  emphasize,  however,  that
lower vapor levels may be  inhibitory on  psychophysiological func-
 tions after longer periods of exposure.   They  also  point out that
 substantial differences were  observed in  toluene uptake among indi-
 vidual  test  subjects,  suggesting  that  CNS effects may  also vary
 from person to person.   Astrand, et al.  (1972)  demonstrated that
 exercise can double respiratory uptake of toluene.  They  advocated
 reconsideration of the current exposure  limit,  since  the preceeding
 studies of  impairment of  performance  have  involved evaluation  of
 resting subjects.
      Toluene,  upon acute exposure, appears to have only  a  limited
 toxicity potential, other than its capacity to  inhibit CNS function
 and  predispose subjects  to cardiac  arrhythmias.   Even exposures to
 quantities of toluene sufficient to produce unconsciousness fail to
 produce residual  organ  damage  in  human  victims  (Longley,  et  al.
                                C-19

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1967; Reisen,  et al. 1975).   Evaluations of experimental animals
subjected to large doses of  toluene  also  indicate that the chemical
is relatively nontoxic.   Svirbely,  et al.  (1943) could find no con-
spicuous pathologic changes  in organs of mice exposed to high vapor
concentrations of  toluene.   Bruckner and Peterson (1976) detected
only slight, transient  rises  in  serum glutamic-oxaloacetic trans-
aminase (SCOT) activity  in mice that  inhaled 4,000 ppm toluene for
three hours.  Divincenzo and Krasavage (1974) administered toluene
at 150,  300, 600, and 1,200  mg/kg to guinea pigs by intraperitoneal
injection.  Twenty-four hours later  they measured serum ornithine-
carbamyl  transferase (OCT)  activity and examined the  livers for
morphologic change.  There was no alteration  in OCT activity at any
dose level.  Only at the highest dosage was there histological evi-
dence of lipid  accumulation.   Reynolds and Yee (1968) included tol-
uene  in  a hepatotoxicity study  because  of  the similarity  of its
lipophilic  solvent properties to  those  of  hepatotoxic  aliphatic
halocarbons.  In contrast to other chemicals  tested, administration
of a 2.4 g/kg oral  dose of toluene to rats  had no effect after 1, 8,
or 24 hours on hepatic glucose-6-phosphatase activity, calcium in-
flux into  hepatocytes,  or liver  morphology.   In  a  subsequent in-
vestigation, Reynolds  (1972)  saw no effect  on a wide  battery of
hepatotoxicity parameters two hours  after giving 2.4 g/kg  of the
chemical to rats.  These findings suggest that any lipophilic sol-
vation action on hepatocyte  membranes by  toluene is of little toxi-
cologic consequence.  Holmberg and  Malmfors  (1974)  provided addi-
tional evidence of the nontoxic nature of toluene by demonstrating
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in vitro that concentrations as high as 100 ug/ml had no cytotoxic
effect on suspensions of ascites tumor cells.
     Toluene appears  to have more  toxicity  potential on subacute
exposure than it does acutely.   In an effort  to assess the capacity
of  toluene  to  elicit injury under  conditions approximating human
solvent abuse, Bruckner and Peterson (1978)  subjected mice and  rats
five times weekly, for eight weeks, to 3-hour cycles of  alternating
fresh  air  and  toluene vapor at 12,000  ppm.   The concentration  of
toluene  employed in this exposure  regimen was not  lethal, but did
produce  inebriation.  A battery of  standard  toxicologic and  histo-
pathologic  tests failed to reveal  evidence of injury to  the lung,
liver,  or  kidney during the 8-week exposure period.   Jenkins,  et
al.  (1970)  found that neither  continuous exposure to 107 ppm tolu-
ene for 90 days nor  intermittent  (8  hours/day,  5 days/week) expo-
 sure to 1,085  ppm  for  six weeks affected body  weight  gain, hema-
 tologic parameters, or the morphology of a number of organs of the
 rat,  guinea  pig,  dog,  or monkey.   Similarly,   Carpenter,  et al.
 (1976) saw no  significant  alteration of any of a variety of  indices
 of toxicity in  rats and dogs exposed to  toluene  concentrate at 988
 ppm for 13 weeks via inhalation.   Toluene concentrate  consists of
 approximately  50 percent  toluene,  15 percent other  alkyl benzenes,
 14 percent heptane,  10 percent  cyclohexane,  and lesser amounts of
 other  hydrocarbons.    Rhudy,  et al.  (1978)  recently  reported  the
 results of  a  90-day pilot study for a chronic  toxicity study sup-
 ported  by  the  Chemical Industry  Institute  of Toxicology.  Male and
  female  rats were exposed  by  inhalation to  99.98 percent pure  tolu-
 ene  at 30,  100,  300,  or  1,000  ppm for  6  hours/day,   5  days/week
                                C-21

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for 13 weeks.  At  any  exposure  level there was no significant al-
teration of a battery of  test results including clinical chemistry,
hematology, urinalysis, and histopathology.  Animal appearance and
behavior  observations,  food consumption,  and mortality  were  not
affected,  although a  slight reduction  in  body  weight  gain  was
exhibited  by  the  high-dose males.   Tahti, et al.  (1977) exposed
rats  to  1,000 ppm  toluene  vapor  eight hours daily  for  one week.
Minimal increases  in serum  glutamic-pyruvic transaminase and glu-
tamic-oxaloacetic  transaminase  activities,  as  well  as  apparent
metabolic  acidosis, were observed.   This  latter  observation is of
interest,  in that Taher,  et al.  (1974)  described  two  cases of meta-
bolic acidosis in  humans  who had  inhaled  toluene  for  its intoxi-
cating effects.  The condition  was  termed renal tubular  acidosis,
because it was believed  to  be due to reversible  alteration of the
ability of the distal renal tubule to acidify the urine.
     Short-term administration of toluene  may influence  the meta-
bolic capacity of   the liver.   It was reported  that Fabacher and
Hodgson  (1977)  saw no  modification  of   liver/bodyweight  ratio,
microsomal  protein content, O-  and N-demethylation,  nor various
spectral characteristics of cytochrorae P-450 in male mice injected
intraperitoneally  for  three consecutive  days with  toluene  at 100
mg/kg body weight.  Other methylated benzenes  and  a methylated
napthalene increased liver weight  and microsomal enzyme activity in
the mice, leading  the authors to speculate  that such compounds were
effective  inducers  because  of  their lipophilicity and persistence
in the body.   Apparently  toluene was  ineffective because  it was too
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readily metabolized and  excreted.   Ungvary, et al. (1976) attempted
to design a protocol that would eliminate the problem of toluene's
rapid  turnover  rate.   They dosed  rats daily  by intraperitoneal
(i.p.) or subcutaneous (s.c.) injection  of analytical grade toluene
at 0.12  to  1.0  ml/kg for 12 days  to  4  weeks.   Dose-dependent in-
creases were seen  in the number and total area of mitochondria per
unit cytoplasmic area in the liver.  Similarly, dose-dependent de-
creases in the average nuclear  volume  were also  observed  in hepato-
cytes of animals receiving i.p. injections.   Subcutaneous injection
was much  less effective in inducing these ultrastructural altera-
tions.   The  enhanced mitochondrial  prominence  is  interesting  in
light of a previous report from the same laboratory  (Aranka,  et al.
1975)  of a dose-dependent  increase in succinic dehydrogenase  activ-
ity and a decrease in glycogen content of livers of  toluene-treated
rats.   The  toxicological or  biological  significance of these find-
ings  is  unclear, although the  investigators have suggested that the
mitochondrial  changes  are  associated   with increased  microsomal
xenobiotic  metabolism.   There is  evidence  that mitochondria  are
 involved in microsomal mixed  function  oxidase  reactions, possibly
 serving to transfer reducing equivalents originating from NADPH or
NADH through cytochrome b5  to cytochrome  P-450 (Schenkman,  et al.
 1973).
      Although  long-term exposure  to  toluene  is quite  common   in
 industry,  there  are few reports  to  suggest that  it  has produced
 deleterious  health  effects  in workers.  One  adverse effect which
 has been tentatively attributed to toluene is myelotoxicity.  Many  of
 the early studies suggested this effect involved the  use of  toluene
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contaminated  with benzene  (NIOSH,  1973).   The  preponderance  of
clinical/epidemiological  investigations  of workers  routinely ex-
posed to toluene vapor has failed to reveal any significant abnor-
malities of  the  circulating  blood and/or  bone  marrow.   Estimated
toluene exposure levels in these negative studies were as follows:
 <200-400 ppm,  Banfer (1961);  80-160  ppm, Capellini  and  Alessio
(1971); 50-800 ppm,  Friborska (1973);  and 60-100 ppm, Matsushita,
et al. (1975). Forni, et al.  (1971)  did not find a significant dif-
ference in  the  frequency  of  chromosome  aberrations  in peripheral
blood lymphocytes between toluene-exposed workers and matched con-
trols.   In  contrast,  stable and unstable  chromosome aberrations
were  significantly  higher in  individuals with  benzene  exposure.
Greenburg, et al.  (1942)  examined 61  painters who were exposed to
solvent mixtures containing   largely  toluene.    There was  a  mild
macrocytosis, anemia, and  lymphocytosis in some of the workers, but
no  alteration of differential  leukocyte  counts,  reticulocytosis,
thrombocytopenia, or leukopenia.  Female  employees exposed to tolu-
ene and other compounds through their work with varnishes have re-
cently been  reported to exhibit decreased erythrocyte and thrombo-
cyte  indices  (Syrovadko, 1977).  It should be recognized here that
interpretation of accounts of toxicity in occupational settings is
often complicated by  uncertain  exposure  levels,  variable exposure
patterns,  exposure to multiple chemicals, and/or unrecognized pre-
disposing factors.
     Toluene  exposures  in occupational  settings  commonly   involve
relatively low-level  inhalation and dermal exposure.   Intentional
toluene  inhalation   is  quite a different situation  in  which the
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participant  inhales  sufficient quantities  to  intoxicate himself.
This practice  may  be continued  for  years.   Despite  such extreme
exposure conditions  and  participation by large  numbers of people
throughout   the  world,  hematological  abnormalities   in  toluene
abusers  are  uncommon.   Massengale, et al.  (1963)  found no irreg-
ularities  in the blood of 27 adolescents who sniffed  toluene-based
glues.   The  only hematologic abnormality in 16 other  glue  sniffers
examined by  Press  and Done  (1967)  was eosinophilia  in 4 of  the  16.
A  number of persons  who developed  polyneuropathies   upon  abusing
glues  containing large  amounts  of toluene  and  n-hexane  exhibited
no  evidence  of hematotoxicity  (Suzuki, et  al.  1974;  Goto, et  al.
1974;  Shirabe,  et  al. 1974; Korobkin, et al. 1975; Towfighi, et al.
1976).   Powars  (1965)  did, however, treat six  cases  of  aplastic
anemia.  Each  of the victims  demonstrated  pre-existing sickle-cell
disease and  had abused a toluene-based  glue.
      Results of evaluations of the myelotoxic potential of toluene
 in laboratory  animals have  generally indicated that the chemical is
 nontoxic.    Wolf,  et  al.  (1956)  have apparently  conducted the only
 long-term toxicity study in which  toluene was given orally.  Female
 rats  received  toluene at 118,  354,  or  590  mg/kg five  times weekly
 for six months.   Cell counts  of bone marrow  and circulating blood
 revealed no adverse effects.   Takeuchi  (1969)  saw no  alterations  in
 peripheral  blood  counts in rats exposed  8  hours/day  by  inhalation
 to  200, 1,000,  and 2,000  ppm of  99.9  percent  pure  toluene for  32
 weeks.  Rhudy,  et al.  (1978)  failed to detect  any hematologic ab-
 normalities in male and  female  rats subjected  6  hours/day,  5
 days/week  for 13  weeks to  30,  100,   300,  or   1,000  ppm of  99.98
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percent pure toluene.  This investigation served as a pilot for an



ongoing 2-year inhalation exposure study (Gibson, 1979).  The pri-



mary difference in experimental design between the two studies has



been a change in the  strain of rat and the deletion of the 1,000 ppm



exposure level.  Findings  after  18  months  of the chronic study do



not indicate an adverse effect at any vapor level on the circulat-



ing blood or bone marrow of the male  or female rats (Gibson, 1979).



In a study of toluene-benzene interaction in mice, Andrews, et al.


                                                              59
(1977)  noted  that  toluene  had no effect on incorporation of   Fe



into developing erythrocytes.  Toluene  actually protected against



inhibition  of  this  process by benzene.  Yushkevich  and Malysheva



(1975)  saw  no alteration  in  erythroblast  maturation  in  the bone



marrow  of  rats subjected  four  hours daily for four months  to a



topical application  of toluene  at  10  g/kg.  This  rather unusual



dose  regimen  was  said to  impair  leukopoiesis,  as  evidenced by an



increase in  the number of  plasmic and  lymphoid  reticular cells in



the marrow.   Topical application of 1 g/kg daily  was without ad-



verse effect  in  this regard.  Horiguchi,  et al.  (1976)  observed



leukocytosis  within  10 days  in  mice that   inhaled 1,  10,  100, or



1,000 ppm toluene 6  hours/day.   Decreases  in circulating erythro-



cytes were  seen  in  the mice  exposed to 100 and  1,000  ppm, while



thrombocytopenia was said to occur in those  exposed to 10, 100, and



1,000 ppm.  A slight hypoplastic change was noted in the bone mar-



row of  the  group subjected  to 1,000  ppm  toluene.   Dobrokhotov and



Enikeev (1977) also observed leukocytosis accompanied by chromosome



damage  in the  bone  marrow  of rats subjected four  hours daily for



four  months  to  112  ppm  toluene  vapor.    Benzene  also  elicited
                               C-26

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chromosome damage, which was  additive  to  that of toluene when the
two chemicals were administered  together.  One month after termina-
tion of the exposure, the leukocytosis had resolved, but the chro-
mosome abnormalities persisted.  The "positive"  findings published
by Yushkevich and Malysheva (1975), Horiguchi, et al.   (1976), and
Dobrokhotov and Enikeev (1977)  should be  interpreted with caution,
in light of the substantial number of studies of  humans  and animals
in  which no  evidence of  toluene-induced myelotoxicity  has  been
seen.  It is  often difficult  to fully appreciate experimental  con-
ditions  and  protocols,  to  interpret data, and to judge the  valid-
ity/significance  of  findings  in translations of  reports in  foreign
languages.   For example, the  purity of  the  toluene  used in  each  of
the  three aforementioned studies  is not stated.  However, the find-
ings of  these investigators  should  not be entirely dismissed,  as
they may prove  to be subtle,  heretofore unrecognized  hematopoietic
responses  to toluene.
      Several reports  have  appeared  in  the literature which  link
long-term solvent exposure  to altered immunocompetence.  Lange and
coworkers (1973a) investigated  serum complement  levels, serum immu-
noglobulin levels,  and  leukocyte  agglutinins  in  persons  exposed
occupationally to   benzene,  xylene,  and  toluene.    IgG  and  IgA
 (Lange,  et al. 1973a) and complement  (Smolik, et  al.  1973)  levels
were lower in these persons  than  in controls.   Ten of 35 solvent-
 exposed  workers  had leukocyte  agglutinins  (Lange, et  al.  1973b).
Nevertheless, it  was not  possible to attribute these effects to any
 single solvent.   Capurro  (1976)  described  in  a  recent  letter  to
 Lancet his  observation of  changes in gamma globulin fractions and
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increased prevalence of  colds  and susceptibility to streptococcal
infections in persons who worked  at  or  lived  near chemical plants
which utilized large quantities of solvents.  Bernshtein  (1972) did
report an  inhibitory effect on phagocytic  activity of  leukocytes
taken  from  rats exposed  via  inhalation  to  185  ppm toluene four
hours daily  for  six months.   In  contrast,  Friborska (1973) noted
increases  in alkaline phosphatase,  acid phosphatase,  and lactic
dehydrogenase activities in leukocytes and/or lymphocytes of work-
ers exposed  to  toluene.   The authors associated  these alterations
with increased functional capacity of the cells.
     Solvent exposure has also been  tentatively linked with  induc-
tion of autoimmune  disease.   A  substantial number  of patients diag-
nosed as having glomerulonephritis were found  to have had a history
of intensive, long-term solvent exposure (Beirne and Brennan, 1972;
Zimmerman, et al. 1975).   These investigators  noted  that  individual
host  susceptibility was  likely   to  be  an  important factor here,
since  so many persons  are  routinely exposed  to solvents  without
developing the disease.   As was the case for the alterations  seen
by  Lange and associates,  no  individual  component  of the  complex
solvent  mixtures utilized by the  glomerulonephritis patients could
be considered the  potential toxicant.
     Long-term exposure  of  toluene  appears  to have  little capacity
to  injure  the liver and most  other  organs.   The only report  sug-
gesting  an adverse  effect of toluene on the  liver in an occupation-
al  setting was in  an early  paper  by Greenburg, et al. (1942).   They
observed an  increased incidence of hepatomegaly in painters exposed
from  two weeks  to   five years  to  solvent  mixtures in which toluene
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was the major  component.   Analyses of  air  samples  taken from the
work environment revealed  exposure  levels  ranging  from 100 to 1,100
ppm toluene.  Capellini and Alessio (1971) saw no changes in liver
function in 17  workers  exposed  for several  years to approximately
125 ppm toluene.  There has also been a surprisingly low incidence
of hepatorenal  injury  in  persons  who  purposefully inebriate them-
selves with toluene.  Litt, et  al.  (1972),  for example,  found mod-
est  elevations of  serum  glutamic-pyruvic  transaminase  levels  in
only  2  percent and  elevated alkaline phosphatase levels in 5  per-
cent of a group of 982 glue sniffers.  Massengale, et al.  (1963) and
Barman, et al.  (1964) failed to detect hepatorenal injury in groups
of  abusers of  toluene-based  glues.    Press  and Done   (1967) saw
slight  but transient abnormalities  in  urinalyses of a  small  per-
centage of the glue sniffers  they examined.  No evidence of  liver
injury was detected.  These investigators concluded that should any
adverse effects occur,  they would  be transient and would occur very
soon  after intensive  solvent  exposure.  This  supposition  is  sup-
ported by a study by Bruckner and Peterson (1976), who demonstrated
 that  intensive inhalation exposure of  mice  to  toluene  is  followed
 by small,  reversible increases  in  serum levels of certain cytoplas-
mic  enzymes.    Signs   of liver   (Weisenberger,  1977)   and  kidney
 (Kelly, 1975)  injury in toluene abusers being treated for behavior-
 al problems cleared spontaneously during hospitalization.
      Clinical  findings from evaluations  of  solvent abusers should
 be interpreted with caution when  considering the toxicity of spe-
 cific chemicals such as  toluene.   Patterns and frequency  of expo-
 sure  may  differ  markedly  among  individuals.    The  commercial
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products favored by many abusers are usually complex mixtures of dif-



ferent compounds.  The formula  for any  given  product often varies



from one manufacturer  to  another and can be  changed at any time.



The abuser may use a variety of solvent-containing products, often



in combination  with  alcohol and  other  drugs.   Thus,  chemical or



drug interactions may either protect  the  participant or place him



at increased risk. O'Brien,  et  al. (1971),  for example, reported a



case of serious hepatorenal injury in an adolescent who drank beer



and inhaled a cleaner containing  80  percent toluene.  A number of



serious cases  of polyneuropathy  were  seen  in persons  who abused



products comprised largely of toluene and  n-hexane.   Signs  of hepa-



torenal  injury  and hematotoxicity,  however,  were  notably absent



(Shirabe, et al.  1974; Suzuki, et al. 1974;  Korobkin, et al. 1975;



Towfighi,  et  al. 1976).   An individual  who  claimed to  have re-



stricted his  sniffing to  pure  toluene  exhibited hepatomegaly and



impaired liver  function  when hospitalized  for  a psychiatric dis-



order  (Grabski,  1961).  This same patient was seen at a later time



when he developed severe hepatorenal toxicity from sniffing carbon



tetrachloride vapor (Knox and Nelson, 1966).



     Long-term  animal studies  have generally  revealed little evi-



dence  of any residual toxic effect of toluene.   Two  investigations



which  deserve   special  attention at  present  are a  6-month oral



dosing study  by Wolf and his  co-workers  (1956)  and an ongoing  2-



year project (Gibson, 1979).  Wolf, et  al.  (1956)  gave  female rats



toluene at 118, 354,  and  590  mg/kg in olive oil by stomach tube five



times  weekly  for 193  days.   Ten animals were  used at each dose



level.   No adverse  effects  on  growth, mortality,  appearance and
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behavior, organ/body weights,  blood-urea nitrogen levels, bone mar-
row counts, peripheral blood counts, or morphology of major organs
were noted.  Thus,  on the basis  of  these findings,  it would be con-
cluded that the minimum toxic oral dose of toluene must be greater
than 590  mg/kg/day.   After 18 months  of the  ongoing 2-year inha-
lation study, no significant  effects  attributable  to toluene have
been seen in male or female rats subjected  6 hours/day,  5 days/week
to  30,  100, or  300 ppm  of  99.98  percent pure  toluene  (Gibson,
1979).  Parameters being evaluated  include food consumption, body-
weight gain, mortality, general  appearance  and behavior,  peripheral
blood counts, clinical chemistry indices, urinalysis indices, organ
weights,  and histopathology of  42  tissue specimens and of any de-
tectable  tissue mass from  each  animal.
     Considerably more  is  known about  the  acute effects of toluene
on  the  central nervous system  (CNS) than  potential  adverse  neuro-
logical effects of chronic exposure to the chemical.   Depressant  or
inhibitory effects of  toluene  on  the  CNS are usually  considered
rapidly  reversible.   Their duration is dependent  upon  the  rate  of
desaturation,  or clearance of  toluene  from the CNS.   Peterson  and
Bruckner (1976)  found  a high degree of correlation between the  de-
gree  of  performance  inhibition  and  the  toluene concentration in the
brain of the mouse.  Several  cases of residual CNS damage have  been
reported involving individuals  who sniffed toluene or solvent  mix-
tures containing toluene over a period  of years.   One of  the  ear-
liest reports was  by  Grabski  (1961),  who examined  a 21-year-old
male  who  had  inhaled  toluene  vapor  on a regular  basis  for  two
years.    The  patient's CNS  signs  were said to be consistent  with
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cerebellar  degeneration.    After  several  more  years  of  toluene
abuse, the same patient was  reexamined  by  Knox  and  Nelson (1966),
who diagnosed the  man as having  diffuse  encephalopathy and cerebral
atrophy.   Satran  and Dodson (1963) related the  case  of a man who
exhibited personality changes including increased irritability and
exaggerated swings in mood over a 10-year period of toluene abuse.
Although his  neurological  exam  was normal, nonspecific abnormali-
ties were observed in his  EEC.   Satran and  Dodson (1963) termed the
condition diffuse encephalopathy.   Another report  of  cerebellar
damage was recounted by Kelly (1975).   In  this case a teenage girl
with a past record of multiple drug and solvent  abuse wasj. found to
have  residual cerebellar  dysfunction after  lh  years  of  inhaling
fumes of  a  toluene-based  paint.   Two additional cases  of cerebral
involvement, each apparently the result  of  inhalation  of 99 percent
pure  toluene, have  recently been described  by Boor  and  Hurtig
(1977).   One  of  the patients had  abused toluene for 10 years be-
fore being hospitalized for  ataxia.  No abnormalities were evident
in his EEC,  but a computerized  brain scan  showed diffuse cerebral
atrophy.   An electromyogram and nerve conduction  studies  of all
limbs showed  no  abnormalities of  nerve or muscle.   Although the
condition of  the patient improved significantly, the central neuro-
logical  abnormalities were  still  evident upon examination  nine
months  later.  The  second  patient was exposed occupationally  to
toluene.  He  had  gradually developed a number of bothersome  prob-
lems,  including  fatigue,  clumsiness   of  his   left  side,  mildly
slurred  speech, impairment  of sense of  hearing  and  smell, and dis-
turbance  of memory  and  power of  concentration.  He showed  daily
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improvement and  recovered  completely without  specific treatment.
Recovery  from  cerebellar dysfunction,  coupled with  optic  neuro-
pathy, has also  been  described  in an individual who inhaled fumes
from a toluene-based paint on a  daily basis  for  three years  (Keane,
1978).  On the  basis  of the aforementioned accounts,  it would ap-
pear that prolonged,  intensive  inhalation of toluene may result  in
damage of the central nervous system, with impairment of pyramidal,
cognitive, and cerebral functions.  The  adverse effects are  largely
reversible,  particularly when  exposure  has not been  too extreme.
Cases  such as these,  however,  seem to  be  a  rare occurrence  even
among  toluene  abusers.
      It  has  been  suggested  that toluene may  influence  the neuro-
toxic  potential of n-hexane  (Suzuki, et al.  1974) or even damage
peripheral nerves  (Goto, et al. 1974), since  a  number  of  persons
have developed  peripheral  neuropathies upon sniffing mixtures  of
 toluene  and  n-hexane.  These neuropathies can apparently be either
 sensory of the "glove and stocking" type, or sensorimotor,  with or
 without amyotrophy (Shirabe, et al.  1974).   It should be  recalled
 that the patient of Boor and Hurtig  (1977) who experienced  cerebral
 dysfunction upon  intensive inhalation  of  99  percent pure  toluene
 exhibited no sensory  or neuromuscular involvement.   In the  majority
 of  reported  cases involving hexane-toluene  mixtures, the victims
 for years had abused products  containing large amounts of toluene
 but no n-hexane without apparent difficulty  (Shirabe, et al.  1974;
 Korobkin, et al. 1975; Towfighi, et al. 1976).  Only a few  weeks to
 months after switching  to products containing n-hexane,  they exper-
 ienced  progressive weakness and numbness  of  the extremities.   No
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report can be located in the literature in which peripheral neuro-
pathy is attributed to the  inhalation of toluene alone.  The possi-
ble contribution of toluene to neurotoxic potential of n-hexane  is
discounted by findings of Suzuki, et al. (1974).  These investiga-
tors administered  n-hexane  at  910  mg/kg alone, and in combination
with toluene at  1.18  g/kg,  by intraperitoneal  injection  to rats.
The toluene  had  no effect on  the  rate  of  elimination of n-hexane
from the  blood,  nor  did  n-hexane  influence  urinary  excretion of
toluene's major  metabolite,  hippuric acid.   It was suggested that
the two  compounds do  not  influence  one  another  because  each  is
metabolized by a different  enzyme  system.   Apparently, no one has
determined experimentally whether toluene can  influence the time of
onset and/or magnitude of n-hexane-induced neuropathy.
     In light of  the apparent residual CNS effects in certain indi-
viduals who subject themselves to  extreme  toluene exposure, it  is
of interest to consider  the likelihood  of  CNS damage  occurring  in
an occupational  setting  where exposure  levels are lower.   Other
than the  transient CNS depressant effects  already  discussed,  few
reports have implicated toluene in  cases of neurological impairment
in industry.  Matsushita, et al.  (1975) did report finding abnormal
tendon reflexes,  reduced grasping  power,  and  decreased agility of
the fingers of  38 female  shoemakers chronically exposed to solvents
including 60 to 100 ppm toluene.  Toluene exposure was  confirmed by
the finding of elevated  urinary hippuric acid  excretion  in these
subjects.  Hanninen,  et  al.  (1976)  also observed  moderate clumsi-
ness of  the  hands  of  car painters exposed  for  years  to solvents.
Thorough analyses  of  the  air  in the  painters' working environment
                              C-34

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revealed the major  component to be toluene  (average  level = 30.6
ppm), with lesser amounts of xylene, methyl  isobutyl  ketone, iso-
propanol, white  spirit,  and other  solvents.   Hanninen,  et al.
(1976) also  observed impairments  in memory, ability to concentrate,
and  emotional  reactivity in the  painters in contrast  to age and
intelligence-matched controls.   These researchers emphasized  that,
while the impairments were quite modest,  such effects  should not be
considered  harmless since they  may  reduce one's  ability to cope
with  the  various  demands of  everyday  life.  Lindstrom  (1973) con-
ducted  a  similar  study  of 168  workers  routinely exposed  to  hydro-
carbon  solvents,  51 of whom were  said  to be exposed primarily to
toluene  or  toluene  and xylene.   Visual  accuracy, psychomotor and
sensorimotor speed  performances of the  solvent-exposed workers were
inferior  to performances  of matched controls.    Axelson,  et al.
(1976)  recently  reported the results of  an epidemiologic study of
workers exposed routinely to hydrocarbon solvents.  These investi-
gators  concluded  that  such  individuals  had  a higher risk  of non-
specific  neuropsychiatric disorders  and  that  the risk  increased
with the number  of  years of exposure.    Axelson,  et al.  (1976) em-
phasized that  such  disturbances, e.g.,  nervousness,  irritability,
insomnia,  and  impairment of  memory and reasoning,  are  so  non-
specific and occur  in  such  variable patterns that they  are often
not  recognized,  nor is  their etiology  appreciated.
      A  very limited  number  of  studies  have been conducted using
laboratory  animals  to   assess  CNS effects  of  toluene  other than
acute depression.   Takeuchi  and Hisanaga (1977)  studied the influ-
ence of inhalation  of 1,000, 2,000,  and  4,000 ppm toluene for four
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hours on  the  behavior  and  EEGs  of  rats with chronically implanted
electrodes.   An increase  in  rearing throughout  the  exposure was
seen  in  rats inhaling  2,000  ppm.    Increased  rearing  during the
first hour was seen in  rats inhaling  4,000 ppm. This early increase
in activity  at  the highest exposure  level  diminished rapidly, so
that the rats became ataxic from hour 2 until the end of the expo-
sure  session.   In  contrast,  Peterson  and  Bruckner  (1976)  saw a
gradual,  but  progressive,  decrement  over  a 3-hour period  in un-
conditioned reflexes/performances tested at 15-minute intervals in
mice and rats inhaling  4,000 ppm toluene.  The inhibitory action of
toluene was  rapidly  reversible  upon cessation of exposure in each
of the aforementioned studies.
     Takeuchi and Hisanaga  (1977) also described EEC changes which
were associated with disturbances in the  sleep cycle of  their  tolu-
ene-exposed  rats.   It  was suggested  that  these  changes  might be
relevant  to  the human  situation in  which  sleep disturbances have
been  attributed to  toluene  exposure.   Although  the toxicologic/
physiologic significance of the EEC  changes in  rats is uncertain,
Takeuchi  and  Hisanaga  (1977)  speculated  that there could be  a  re-
lationship between the  sleep-related  changes and  abnormal EEC pat-
terns reported  in  glue  sniffers (Miyaska, et al.  1971)  and persons
with prolonged  occupational exposure  to organic solvents  (Mabuchi,
et al. 1974).
     Ikeda and  Miyake  (1978)  conducted an  investigation  to  deter-
mine whether  long-term  toluene  exposure, under  conditions approxi-
mating  those  in glue sniffing,  could have  a detrimental effect on
learning  and  memory.  Rats were subjected two hours daily to 4,000
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ppm of toluene vapor  for  60  days.   Several days later spontaneous
activity,  emotionality,   and  memory-learning  on  three  different
schedules were evaluated.  No influence of the  toluene regimen was
seen on any parameter except one of the memory-learning tests.  The
particular test which was affected was the most complicated or dif-
ficult for  the  rats to perform,  suggesting  that higher cognitive
processes  may be  impaired  by  toluene abuse.   Recovery from  this
impairment had not occurred 80  days after the  final  toluene expo-
sure.   Microscopic  examination of several  areas  of the  brain  of
these  animals did not reveal any  damage.   Furnas and Hine  (1958)
also  failed  to detect histopathologic damage of sections of brain,
spinal cord,  and  sciatic  nerve  of  rats 24 hours after they had  been
subjected  to toluene  vapor  at  20,000 ppm for  six  consecutive  30-
minute exposures.  Ishikawa and Schmidt (1973)  found no histopatho-
logic lesions in  brains of  rats that developed  a tendency  to circle
 in their cages after inhaling high concentrations of toluene for a
week.   This condition,  termed "forced  turning,"  was reversible.
 Inoue (1975) reported that  mice which inhaled  1, 10,  100,  and 1,000
 ppm toluene for six hours daily showed a decrease in wheel turning
 activity within  6 to 10 days.    This finding  seems questionable,
 in light of the  lack of  inhibition of spontaneous  activity, such as
 wheel turning,  in rats  which  inhaled 4,000  ppm toluene  two hours
 daily for 60 days  (Ikeda and Miyake, 1978).
 Synerqism and/or  Antagonism
       Toluene, in sufficient amounts, would appear  to have the  po-
 tential to  significantly alter the metabolism  and  resulting bioac-
 tivity  of  certain other  chemicals.  The time  at which  exposure  to
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toluene occurs, relative to exposure  to  a  second chemical, could be
quite important.  Prolonged pre-exposure  to  toluene  may induce or
stimulate mixed-function oxidase (MFO) activity, thereby enhancing
metabolism of the second chemical.   Should concurrent exposure oc-
cur, toluene, which  is  readily hydroxylated  by the microsomal MFO
system, would  probably  inhibit the metabolism  of  other compounds
which are  acted  upon by this  same system (Ikeda,  1974; Ikeda, et
al. 1972).   This phenomenon would be  anticipated  to  result  in a
prolonged  half-life  of  both toluene and  the  other  compound.   In-
hibition of metabolism  of  a second compound may be  beneficial or
detrimental from the standpoint of adverse effects, depending upon
the toxicity of  the  parent  compound  versus  its metabolite(s).   It
might also be noted  that toluene undergoes alcoholic oxidation and
conjugation reactions subsequent to the  initial hydroxylation reac-
tion.  Therefore,  a  substantial dose of toluene could  conceivably
interfere with the metabolism of compounds which undergo alcoholic
oxidation and glycine conjugation.
     Several animal studies have demonstrated that  toluene can sig-
nificantly influence the  biological  fate and  bioeffects of other
agents.  Ikeda (1974) demonstrated  that  toluene at  430 mg/kg, given
to rats by intraperitoneal  injection  in  combination with trichloro-
ethylene,  reduced  the metabolism of  the trichloroethylene.   Tolu-
ene's metabolism was also  diminished.   Ikeda,  et  al. (1972) found
that  simultaneous  intraperitoneal administration  of  toluene  and
benzene to rats  resulted in suppression of  the metabolism of both
compounds.  The  mutual  suppression was  reflected  in diminution of
urinary excretion of  phenol and hippuric acid.  Coadministration of
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toluene and styrene was also shown to decrease styrene metabolism.
Pretreatment of the rats with phenobarbital alleviated the suppres-
sant effects  of toluene.   Andrews,  et  al.  (1977), coadministered
benzene at 440 or 880 mg/kg  and  toluene  at 1,720 mg/kg intraperito-
neally to mice and observed  a marked reduction in  urinary excretion
of  benzene metabolites,  coupled  with a compensatory  increase  in
pulmonary  excretion  of unmetabolized  benzene.   It was demonstrated
using  liver microsomes in vitro that toluene is a  competitive  inhi-
bitor  of benzene metabolism.  When  toluene and benzene were  given
concomitantly by  subcutaneous  injection,   it  was determined  that
 toluene  did  not  significantly  reduce the  total  amount of  benzene
 appearing in body tissues,  but markedly reduced  the  concentration
 of benzene metabolites  in  various tissues including  bone  marrow.
 Toluene was also found to protect against the inhibitory effect of
 benzene on  59Fe incorporation into  developing erythrocytes, sug-
 gesting  that toluene may  guard  against benzene myelotoxicity by
 inhibiting benzene metabolism  in bone marrow.
       It has  been suggested  that  toluene may  play a role in  induc-
 tion  of peripheral neuropathy seen in some abusers of n-hexane/tol-
 uene  mixtures.  However,  as  previously discussed, available  evi-
 dence indicates  that n-hexane  is responsible for  the  neurotoxicity.
 Suzuki, et al. (1974) showed that n-hexane and toluene given concur-
 rently  to rats had no apparent effect  on  one another's  metabolism
 elimination.
 Teratogenicity
       Toluene has been shown  to  be teratogenic in one  recent study
  by Nawrot  and Staples  (1979).   Toluene  was  administered  to CD-I
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 mice by gavage on days 6  through 15  of gestation at levels of 0.3,
 0.5, and 1.0  ml/kg body wt/dose.   A  significant increase in embry-
 onic lethality  occurred  at  all  dose  levels  and decreased  fetal
 weight  occurred at 0.5 or  1.0  ml/kg.  in  the  1.0 ml/kg  group,  a
 statistically significant increase in  the incidence of cleft palate
 was  noted which did not appear to be  due merely  to general retarda-
 tion in growth rate.   The same  toluene regime administered on days
 12 through  15 yielded  only  decreased  maternal weight  gain.   Mater-
 nal  toxicity  was  not  seen  after exposure  to  toluene at  any  dose
 level.
      Several  researchers have reported that  toluene  is  not terato-
 genic.   Roche and Hine (1968) concluded  that  neither benzene  nor
 toluene  was  teratogenic  to  the  rat  fetus  or   the  chick  embryo.
 Parameters  evaluated by these investigators included body  weight,
 bone  length,   and  incidence  of  gross  abnormalities.   Hudak  and
 Ungvary  (1978) also concluded that benzene and  toluene,  as  well as
 xylene,  were  not teratogens  in mice  and  rats.   These  researchers
 assessed a  battery of  indices of  teratogenicity.  Mice exposed 24
 hours/day on  days 6 to 13  of pregnancy gave birth to  underweight
offspring.   Some retardation of  body weight and  skeletal  growth
were seen in  fetuses of rats exposed continuously  to  399  ppm  tolu-
ene  on  days  1  to 8 of pregnancy.   No effects were noted  in a
variety  of  other  indices  including  the incidence  of external and
 internal malformations.   Inhalation  of 266  ppm toluene for eight
hours each day of days 1 to 21 of pregnancy had  no apparent  influ-
ence on  any index  in the  rat.   Hudak and  Ungvary  (1978) concluded
from  quite  limited  data  that  toluene   exposure  during  early
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pregnancy might  retard  fetal development and  should  therefore be
avoided.  It was  noted  that  toluene  should readily pass the placen-
tal barrier  and  reach  embryonal cells.   Syrovadko (1977) recently
reported  that  a  group  of women  occupationally exposed to toluene
and other  solvents  through  the use of varnishes exhibited a  rela-
tively high incidence of menstrual disorders.   The newborn children
of  these  women were  said  to  experience more frequent  fetal asphyx-
ia,  to be  more  often  underweight, and not  to nurse  as  well  as
"normal"  infants.  Matsushita,  et al.  (1975)  found  dysmenorrhea to
be  a frequent  complaint of female shoemakers exposed chronically to
60  to  100 ppm  toluene.  There are no accounts,  however, of a terato-
genic  effect in  humans being linked to toluene exposure.
Mutagenicity
      There is no conclusive evidence that toluene is mutagenic.  In
 a recent  review  of  the genetic  toxicology of  toluene and  related
 compounds, Dean  (1978)  stated  that no data are available on muta-
 genicity  testing of  toluene  in bacterial  systems.    Dean   (1978)
 noted  that  since toluene is a lipophilic solvent,  high concentra-
 tions could  conceivably  alter  the  penetration of other substances
 into  cells.   Lyapkalo (1973) was  able to produce chromatid  breaks
 and gaps in  11.5 percent of bone marrow cells of rats by injecting
 the animals  with 1  g/kg  of  toluene daily for  12  days.   Benzene,  in
 contrast, caused chromosome damage  in 57 percent of cells examined.
 Dobrokhotov and Enikeev (1977) found that  inhalation of  112 ppm
  toluene  four hours daily for four  months  resulted  in leukocytosis
  in rats  and  chromosome damage  in 21.6 percent  of bone marrow cells.
  Although  inhalation   of benzene  caused  a   similar  incidence  of
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 chromosome  damage, leukopenia  rather  than leukocytosis  occurred.
 The myelotoxic effects of toluene and benzene were found to be add-
 itive  when  both chemicals were inhaled together.  One  month  post-
 exposure, the  abnormalities  in peripheral blood had resolved,  but
 the  chromosome  aberrations  persisted.   Dobrokhotov  and  Enikeev
 (1977) estimated that toluene at 0.8 g/kg/day induced the  same fre-
 quency  of  chromosome  damage   in  their  rats  as  benzene  at  0.2
 g/kg/day.  In a study of peripheral blood  lymphocytes of humans who
 had been exposed to an average of 200 ppm toluene for as long  as 15
 years, Forni, et al.  (1971)  did not detect any greater  incidence of
 chromosome  abnormalities  than  in  controls.   Workers with  benzene
 exposure, however, did exhibit  a significantly higher proportion of
 unstable and  stable  chromosome aberrations than did the  controls.
 Dean  (1978)  concluded  that  in light  of  the  apparent  absence  of
 chromosome damage  in humans and the exceedingly high  concentrations
 of toluene required to induce aberrations in  animals, the  exposure
 limit currently  recommended  by NIOSH of 100 ppm would most likely
 protect  against  chromosome  damage in occupational  exposure   set-
 tings.
     A significantly increased  frequency of abnormal lymphocytes and
 chromosomal breaks has, however, been  shown in recent findings  on
workers exposed  to toluene  in  a rotoprinting factory and  chemical
 laboratories (Funes-Cravioto, et al. 1977).
     It  seems  unlikely  that metabolites  of  toluene  will induce
mutations in animals  exposed  to toluene.   Benzoic acid and  hippuric
 acid,  the principal  metabolites of  toluene,  are rapidly   excreted
and  generally  regarded  as  innocuous  chemicals.    Cresols   are
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relatively minor metabolites of toluene  which have  been examined by
Sharma and Ghosh  (1965)  for their ability  to damage chromosomes.
These  investigators  found  that high  concentrations could produce
chromosomal  aberrations  in  cells  from  root tips   of  Alii* cej>a
bulbs.   Of the  three isomers,  m-cresol caused the  most  pronounced
changes.  It will be recalled that  urinary cresols  represented only
about  one  percent of a total dose of toluene  given to rats, and that
no m-cresol  was detected  (Bakke and Scheline, 1970).
Carcinogenicity,
      Toluene has not  been demonstrated  to  be positive  in  any In
vitro mutagenicity/carcinogenicity bioassay system, nor to be car-
cinogenic in animals or man.  Pluck,  et al. (1976) tested toluene
 and benzyl alcohol  for their  carcinogenic  potential in an E. coll
 screening system and  found both  compounds  to  be  negative.   These
 researchers, however, discounted  the applicability  of  the  system
 for evaluation of  lipophilic chemicals  due to the chemicals'  in-
 solubility  in  the  aqueous test medium.   Toluene has been utilized
 extensively as a solvent  for  lipophilic  chemicals being tested for
 their carcinogenic  potential  when applied  topically to  the  shaved
 backs of  animals.  Poel  (1963), for example, topically applied tol-
 uene  throughout the lifetime  of  mice  being used as controls  and
 found no  carcinogenic  response.   Doak,  et al.  (1976) applied tolu-
 ene to  the  skin of mice  for one year and failed to elicit skin neo-
 plasms  or  an  increased   frequency of  systemic tumors.   It  is not
 clear  in  these papers,   however, whether  the  toluene  was   applied
  under an occlusive dressing or simply allowed  to  evaporate.  LiJin-
  sky and Garcia (1972) did report  a skin papilloma in one mouse  and a
                                 C-43

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 skin carcinoma in a second mouse in a group of 30 animals which were
 subjected to topical  applications  of  16 to 20 ul of toluene twice a
 week for 72 weeks.  Mazzucco  (1975)  found  a  reduction in collagen
 content of the skin of mice subjected to epidermal  paintings  with
 toluene  three  times  weekly  for   10  weeks.   There  was  a  shorter
 latency period in these  animals  for  tumor  development  when toluene
 rather  than acetone  was used as  the solvent for  3-methylcholan-
 threne.   There has been no increase  in tumor incidence  in  experi-
 mental  rats as  compared to controls after 18  months  of a  2-year
 toluene  inhalation study (Gibson,  1979).   In this study, male  and
 female  rats  have  inhaled 30, 100, or 300  ppm toluene 6  hours/day,  5
 days/week.   Forty-two tissue  specimens per animal, as well as  any
 detectable  tissue mass, are  being subjected  to histopathological
 evaluation.
     There  have  been  no  accounts in the literature  in  which cancer
 in human  populations  has been  attributed  specifically to toluene.
 Some researchers  have, however, suggested that chronic exposure  to
 hydrocarbon  solvents may predispose certain individuals  to certain
 types of  cancer.   Capurro  (1976)  reported  four cases  of lymphoma
 and two cases of pancreatic cancer  among workers and  persons living
 near chemical  plants  where mixtures  of  hydrocarbon solvents were
 said to be  present often.   Capurro (1976)  felt  that both forms of
 cancer were  so  rare that it was  unlikely  they would have occurred
 in such  a small population by chance.   McMichael,  et al.  (1975)
 conducted an epidemiological  study of rubber  industry workers who
were routinely exposed to a variety of solvents.  The investigators
 found a greater  than  expected  risk of death from  cancer, with the
                              C-44

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largest mortality excesses  from  lymphosarcoma,  Hodgkin's disease,
lymphatic leukemia, and myeloid  leukemia.   Upon testing the hypo-
thesis that  the  excess in  cancers was  due  to hydrocarbon solvent
exposure, an association was established  between duration and in-
tensity  of  solvent exposure and  incidence  of lymphatic leukemia.
Curtes,  et  al.  (1973)  reported  the case  history of a man who had
worked with solvents, including toluene, who subsequently developed
chronic  myeloid  leukemia.   McMichael  and his associates point out
that  benzene does not appear to cause lymphatic leukemia, but rath-
er  the  hemocytoblastic and  myeloblastic  forms of  the  disease.
Thus, it is suggested  that  another solvent or other chemical may be
 responsible for  lymphatic leukemia and other forms of  cancer  seen
 in the  study.   The  researchers also  stress that there  has  been
 inadequate  carcinogenicity  testing in animals and insufficient epi-
 demiological studies of the carcinogenic  potential  of many solvents
 generally  regarded  as noncarcinogenic.   It should  be recognized
 here that  situations  involving  persons with occupational exposure
 to  solvents  are  characterized  by considerable job  mobility and
 exposure to a variety of chemicals in  varying  patterns.  Wolff,  et
 al.  (1977), for  example,  found toluene  in combination with a number
 of other hydrocarbon  solvents in adipose samples  from  workers in a
 styrene  polymerization plant.   Thus,  it is quite difficult to at-
 tribute  tumor induction  to any  single  agent.
                                C-45

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                       CRITERION FORMULATION
 Existing Guidelines and Standards
      The Occupational Safety and Health Administration (OSHA) cur-
 rently limits occupational toluene exposure to 200 ppm as an 8-hour
 time-weighted  average  (TWA)  concentration,  with a ceiling  of  300
 ppm (40 CFR 1910.1000).  The National Institute  for  Occupational
 Safety and Health  (NIOSH, 1973)  has recommended  an exposure limit
 of  100 ppm as an 8-hour TWA with a ceiling of 200 ppm.   This criter-
 ion was  recommended primarily on  the basis of subjective and objec-
 tive  signs of mucus  membrane irritation  and  deficits in  central
 nervous  system  function  upon acute inhalation  exposure of  human
 subjects  to 200  ppm toluene.  Short-term  inhalation of  100  ppm  was
 apparently without demonstrable effect in humans.  Reports reviewed
 by NIOSH  (1973) also have failed to indicate adverse effects on  the
 hematopoietic, hepatorenal,  or  other systems of  workers  routinely
 inhaling  approximately  100 ppm toluene.
     A  review  of potentially harmful effects of  chemical contami-
 nants  of  drinking water was  undertaken  by the  Committee on Safe
Drinking  Water  of the  National  Academy of  Sciences  (NAS,  1977).
The recommendations of  this  committee  were to  be used by the U.S.
EPA as  the scientific  basis  for revision  or  ratification of  the
Interim Primary  Drinking  Water  Regulations promulgated under  the
Safe Drinking Water Act of  1974.  Toluene  was  one of the organic
chemicals considered by the Committee.  Although it  was concluded
that toluene and  its major metabolite,  benzoic acid, were relative-
ly  nontoxic,  the committee  felt  there  was insufficient toxico-
logical data available to serve  as a basis for  setting a long-term
                              C-46

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ingestion standard.   It was  recommended  that studies be conducted
to produce relevant information (NAS, 1977).  Toluene has recently
been considered for a second time by a reorganized Toxicology Sub-
committee of  the  Safe  Drinking  Water Committee  of  the  National
Academy of  Sciences.   Results of  the  deliberations of this group
have not yet been made public.
     There  are  no  Federal or  State  guidelines,  nor standards for
general atmospheric pollution  by toluene.
Current Levels of  Exposure
     Toluene has been detected in raw water and  in  finished water
supplies of several communities in the United States.  Levels of  up
to  11  jag/1  were  found in finished water from the New  Orleans  area
(U.S.  EPA,  1975a).  In a nationwide survey of water  supplies  from
10  cities,   six  were  discovered  to be  contaminated with  toluene
(U.S.  EPA,  1975b).   Concentrations  of  0.1  and  0.7 ng/1 were  mea-
sured  in  two of  these water  supplies.   Toluene  was  detected in one
of  111 finished  drinking waters during a second  nationwide survey
 (U.S.  EPA,  1977).    In a subsequent phase  of this  survey,  toluene
was found in one raw  water and three finished waters out of 11  sur-
veyed  (U.S. EPA, 1977).   A level of  19 ug/1 measured by gas chroma-
 tography/mass  spectrometry was found in one of  these finished wa-
 ters,  and 0.5  wg/1 was found in another.
      There  is  a paucity  of  data available  on  levels of toluene in
 foods.  Toluene  was detected in  fish caught from  polluted waters in
 the proximity  of petroleum and petrochemical plants  in Japan (Ogata
 and Miyake,  1973).   A  concentration  of  5  ^g/g was  measured in
 the muscle  of  one such  fish.   Two major  metabolites of  toluene,
                                C-47

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benzaldehyde  and benzole  acid, naturally  occur in  foods or  are
intentionally  added.    Benzaldehyde  is  a  flavoring  agent,  while
benzoic  acid  is  a  preservative.   Benzoic  acid  is  also given  in
large oral doses to humans as a clinical method  for measuring  liver
function.
     Although toluene has been  detected in  the  atmosphere,  concen-
trations are many times lower  than vapor levels considered  to  be
potentially harmful in occupational settings.   An atmospheric con-
centration of 39  ppb  toluene was measured  in Zurich, Switzerland
(Grob and Grob, 1971).  An average level of 37  ppb toluene  was  ob-
served in Los Angeles  air  in 1966 (Lonneman,  et al. 1968).   The max-
imum amount  detected  there  was 129 ppb.   Comparable levels were
found upon evaluation  of air  in Toronto, Canada  (Pilar and Graydon,
1973).    The  maximum concentration of  toluene measured in  Toronto
was 188 ppb,  while the average concentration was 30 ppb.  The  atmo-
spheric  levels  of toluene in  both Toronto  and  Los  Angeles varied
considerably according  to the  time  of day and sampling location
(Pilar and Graydon, 1973; Altshuller,  et  al.  1971).   Thus, it  ap-
pears that atmospheric toluene in urban areas  arises primarily from
automotive emissions,  with solvent losses as  a  secondary source.
     The most  significant toluene  inhalation  exposures  occur   in
occupational settings  or via  inhalant abuse.   Occupational exposure
levels are generally  lower than the current  standard  of 100 ppm,
although  short  exposures  to  higher  vapor  concentrations occur.
Purposeful inhalation  of toluene vapors in order to inebriate one-
self  is  a quite  different  situation,  since  the participant may
inhale  extremely high  concentrations  repeatedly  for  months  or
                              C-48

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years.  Toluene concentrations as high as 20,000 to 30,000 ppm can
produce intoxication within minutes under such circumstances.
Special Groups at Risk
     At present  levels  of exposure to toluene in the environment,
available toxicological data do not suggest that any special group
in  the general population would be at  risk.  Exposure to  levels of
the  chemical necessary to  produce  physiological or toxicological
effects would be anticipated primarily  in occupational or  solvent
abuse  situations.   Environmental  contribution of  toluene  in  such
settings  should  be  minimal.
Basis and Derivation  of Criteria
      Although acute exposure to high  levels  of  toluene  can result
 in marked central nervous system depression, this action is rapidly
 reversible  upon cessation  of  exposure  in both  laboratory animals
 (Peterson and Bruckner,  1976)  and in man (Longley, et  al. 1967).
 When administered acutely  in quite large doses to animals, toluene
 can alter the metabolism and bioactivity of certain chemicals which
 are degraded by the mixed function oxidase system.  Toluene appears
 to  have  little  capacity  to cause  residual tissue  injury. There  is
 no  conclusive evidence  that the parent  compound or its metabolites
 are mutagenic,  although  they have apparently  not been tested  in  an
 in vitro mutagenicity assay (Dean, 1978).   Although toluene has not
 been  found  to be teratogenic  in chickens  and  rats  (Roche and  Hine,
 1968) or rats and  mice  (Hudak  and Ungvary,  1978),  one  recent  study
 by Nawrot and Staples (1979)  reports teratogenic effects  in  mice.
 Toluene  has not been demonstrated to be  carcinogenic when applied
  to the  skin of  mice  (Poel, 1963;  Doak,  et al. 1976)  or  when admin-
  istered  by  inhalation  at concentrations of  up to 300  ppm  for as
                                 C-49

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long as 18 months to male  and female rats (Gibson, 1979).   There are
no accounts in the literature in which cancer  in  a human population
is attributed specifically to toluene.
     A number of  investigations  of  the subacute  and chronic toxi-
city of toluene have been conducted.  Although the heaviest empha-
sis has been placed  upon  inhalation exposure,  Wolf,  et al. (1956)
did conduct  a long-term, oral  dosing study  in  which female rats
were given toluene at 118, 354, or 590 mg/kg in olive oil by stomach
tube five times weekly for 193 days.   No  adverse  effects on growth,
appearance and behavior, mortality, organ/body weights, blood urea
nitrogen  levels,  bone  marrow counts,  peripheral blood counts,  or
morphology of major  organs  were observed at any dose  level.   The
lack of  toxicity  reported here  is  supported  by  findings  of other
groups of investigators who  found no evidence of  residual  injury in
a variety of animal species subjected to toluene vapor for varying
times over  periods as  long  as  18 months  (Jenkins,  et al.  1970;
Carpenter, et al.  1976; Bruckner and Peterson, 1978; Rhudy, et al.
1978;  Gibson,  1979).
     Therefore,  it seems reasonable that the highest dose utilized
by Wolf,  et al.  (1956), namely 590 mg/kg, might  serve as  the basis
for calculating  an "Acceptable Daily Intake" for  toluene.  Although
590 mg/kg will be  considered here  as a "maximum-no-effeet" dose,  it
should be recognized that  the  actual  "maximum-no-effeet"  dose may
be higher, since Wolf,  et al.  (1956) did not determine a  "minimum-
toxic-dose."   Reynolds and Yee   (1968)  saw  no  effect  on several
parameters of hepatotoxicity in  rats  given a  single  oral dose  of
2.4 g/kg  toluene.   The  acute oral LD_   for toluene in young, adult
                              C-50

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rats is reported to be  7.0 g/kg (Wolf, et al.  1956).   It is possible
that  the  actual "maximum-no-effeet"  dose may  be  lower  than 590
mg/kg, should alternative indices of toxicity be evaluated.  Humans
may prove  to  be more sensitive to  toluene  than experimental ani-
mals.   Thus,  assuming  a 70 kg body  weight,  it seems appropriate
that  a safety factor of  1,000 be  applied  in  the  following calcula-

tion:
           590 mg/kg  x  70 kg x  5/7 day _ 29.5  mg/day
                     1,000
Therefore,  consumption of 2 liters  of water daily and 6.5 g of con-
 taminated   fish  having  a  bioconcentration factor  of 10.7,  would
 result in,  assuming  100  percent gastrointestinal absorption of tol-
 uene, a maximum permissible  concentration  of  14.3  mg/1  for  the

 ingested water:
           	29.5 mg/day	 =14.3 mg/1
            (21+  (10.7  x 0.0065) x 1.0
      This  calculation  assumes  that  100  percent  of  man's exposure
 comes from water.  Although it is  desirable  to arrive at a criter-
 ion  level  for  water based  upon  total exposure potential, the data
 base  for  exposures other  than water is  not sufficient to allow a

 factoring  of the  criterion level.
       in  summary,  based on the  use  of  toxicologic  test data  for
 rats,  and  an uncertainty  factor of  1,000, the criterion  level  for
 toluene  is 14.3 mg/1.   Drinking  water contributes 97 percent of the
 assumed  exposure, while eating  contaminated fish products accounts
  for  3 percent.  The  criterion  level for toluene  can alternatively
 be expressed as 424 mg/1  if exposure is  assumed' to be from the con-
  sumption of fish and  shellfish products alone.
                                 C-51

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