820K87013
                                                               March  31,  1987
                                    ETHYLBENZENE

                                  Health Advisory
                              Office of  Drinking Water
                        U.S.  Environmental  Protection Agency
I. INTRODUCTION
        The Health Advisory  (HA)  Program,  sponsored  by  the Office of Drinking
   Water (ODW),  provides  information on  the  health effects,  analytical  method-
   ology and treatment technology that would be useful  in dealing with  the
   contamination of drinking water.   Health  Advisories  describe  nonregulatory
   concentrations  of drinking water  contaminants at  which adverse health effects
   would not be  anticipated  to  occur over  specific exposure  durations.  Health
   Advisories contain a margin  of safety to  protect  sensitive  members of the
   population.

        Health Advisories  serve as informal  technical guidance to assist Federal,
   State and local officials responsible for protecting public health when
   emergency spills or contamination situations occur.  They are not to be
   construed as  legally enforceable  Federal  standards.  The  HAs are subject to
   change as new information becomes available.

        Health Advisories  are developed for  One-day, Ten-day, Longer-term
   (approximately  7 years, or 10% of an individual's lifetime) and Lifetime
   exposures based on data describing noncarcinogenic end points of toxicity.
   Health Advisories do not  quantitatively incorporate  any potential carcinogenic
   risk from such  exposure.   For  those substances that  are known or probable
   human carcinogens,  according to the Agency classification scheme (Group A or
   B),  Lifetime  HAs are not  recommended.   The chemical  concentration valuas for
   Group A or B  carcinogens  are correlated with carcinogenic risk estimates by
   employing a cancer potency (unit  risk)  value together with assumptions for
   lifetime exposure and  the consumption of  drinking water.  The cancer anit
   risk is usually derived from the  linear multistage model  with 95% upper
   confidence limits.   This  provides a low-dose estimate of  cancer risk to
   hunans that is  considered unlikely to pose a carcinogenic risk in excess
   of  the stated values.   Excess  cancer risk estimates  may also be calculated
   using the One-hit,  Weibull,  Logit or Probit models.  There is no current
   understanding of the biological mechanisms involved  in cancer to suggest that
   any  one of these models is able to predict risk more accurately than another.
   Because each  model  is based  on differing  assumptions, the estimates  tnat are
   derived can differ  by several  orders of magnitude.

-------
    Ethylbenzene                                                 March 31,  1987

                                         -2-


         This Health Advisory is based on information presented in the Office of
    Drinking Water's Health Effects  Criteria Document (CD)  for Sthylbenzene (U.S.
    EPA,  1985a).  The HA and CD  formats are  similar  for  easy  reference.  Individuals
    desiring further information on  the toxicological data  base or rationale for
    risk  characterization should consult the CD.   The CD is available  for review
    at each EPA Regional Office  of Drinking  Water counterpart (e.g., Water Supply
    Branch or Drinking Water Branch),  or for a fee from  the National Technical
    Information Service, U.S. Department of  Commerce, 5235  Port Royal  Rd.,
    Springfield, VA 22161,  PB #  86-117835/AS.  The toll-free  number is (800)
    336-4700; in the Washington, D.C.  area:  (703) 487-4650.


II. GENERAL INFORMATION AND PROPERTIES (Verschueren,  1983;  Amoore and  Hautala,  1983)

    Chemical Name  Ethylbenzene

    Cas No.        100-41-4

    Chemical Structure
    Synonyms

            Phenyl ethane,  ethylbenzol,  EB

    Uses

            Styrene manufacture
            Acetophenone manufacture
            Solvent
            Asphalt constituent
            Naptha constituent
    Properties
            Chemical Formula              C8H1 0
            Molecular Weight              106.18
            Physical State (25C)          Colorless  liquid
            Boiling Point                 136.2C
            Melting Point                 -94.97C
            Density
            Vapor Pressure                7 mm at 20C
            Water Solubility              152 mg/L (at 20C)
            Log Octanol/Water Partition   3.15
              Coefficient
            Taste Threshold (water)        0.029  mg/L
            Odor Threshold (water)         0.029  mg/L
            Odor Threshold (air)           0.062  mg/L
            Conversion Factor             

-------
     Ethylbenzene                                              March 31,  1987

                                          -3-


     Occurrence
             Ethylbenzene,  a clear,  flammable liquid found in gasoline,  is produced
             commercially by the alkylation of benzene with ethylene.   In 1982,
             the U.S.  production of  ethylbenzene  totaled 3.3 million tons.

             Very little information is  available on the occurrence of ethylbenzene
             in 12,000 drinking  water supplies in the  U.S.  drawing water from
             surface rivers and  streams.  However, the  testing of 945 ground water
             supplies  has revealed  that  approximately  0.6 % contain ethylbenzene.
             The median concentration detected in "non random" segment of the
             study was 0.87 ug/L (Westrick  et al.,  1983).
III. PHARMACOKINETICS
     Absorption
             Data regarding the absorption of  ethylbenzene  from the  gastrointestinal
             tract of  humans following oral ingestion could not be located.

             Since approximately 90% of an oral  dose  of  ethylbenzene (1.78 g/rabbit)
             is  excreted as metabolites (SI Masry  et  al.,  1956),  the chemical  is
             readily absorbed in rabbits.

             For human volunteers exposed  by inhalation  to  ethylbenzene  for  8  hours
             at  100, 187,  200 or 370 mg/m-^,  the  average  percent of vapor absorbed
             (measured spectrophotometrically) through the  respiratory tract was
             64% (Bardodej  and Bardodejova,  1970).

             Absorption of  an aqueous  solution of  ethylbenzene  through human hand  skin
             (109.3 to 113.9 mg/L for  1  to 2 hours) was  equivalent to 118 ug/cm2/hour
             (Dutkiewicz and Tyras,  1967).
     Distribution
             Following a 6-hour  inhalation  exposure  at  1  mg/m3,  absorbed  ethylbenzene
             is  distributed throughout the  body  in  rats.   However,  the highest
             levels  were detected  in  the  kidney,  lung,  adipose  tissue,  digestive
             tract and liver (Chin et al.,  1980).
     Metabolism
             After  inhalation  exposure,  ethylbenzene  undergoes  rapid  metabolism
             in  humans,  primarily  to form  mandelic  acid  and  phenylglyoxylic  acid.
             These  two  metabolites  accounted  for  64%  and 25%, respectively,  of  the
             absorbed dose  in  humans (Bardodej  and  Bardodejova,  1970).   Formation
             of  minor metabolites  including methylphenyl carbinol  and 2-ethylphenol
             accounted  for  approximately 5% and 1%, respectively,  in  humans  (Bardodej
             and Bardodejova,  1970;  Angerer and Lehnert,  1979).

             The major  metabolites  formed  in  humans and  rats are not  the  same.
             Mandelic acid  and phenylglyoxylic  acid constitute  64  and 25% of  the
             metabolites  in humans  (Bardodej  and  Bardodejova, 1970),  while in

-------
    Ethylbenzene                                               March 31, 1987

                                         -4-
            rats,  1-phenylethanol (25%),  benzole acid (27%)  and mandelic acid
            (25%)  are the main metabolites (Engstrom, 1985).
    Excretion
            Urinary excretion of metabolites by rabbits was reported to be
            complete within 24 hours after oral dosing with 1.78 grams/rabbit
            (El Masry et al., 1956).

            In humans,  most of the inhaled dose was  eliminated in the urine
            within 24 hours after exposure was terminated (Engstrom and Bjarstrom,
            1978;  Hagemann and Angerer,  1979).
IV. HEALTH EFFECTS
    Humans
         0  In experiments with human volunteers,  an 8-hour inhalation exposure
            to ethylbenzene at a concentration of  100 ppm (435  mg/m3)  did not
            result in adverse health effects (Bardodej and Bardodejova, 1970).
            Increasing this level (increase not specified)  resulted in sleepiness,
            fatigue, headache and mild eye and respiratory irritation.

    Animals

    Short-term Exposure

         0  Estimated acute LD^Q values of 3.5 g/kg to 5.46 g/kg  were  reported  in
            rats (Wolf et al., 1956; Smyth et al., 1962).

         0  An acute dermal LD50 value of 17.8 ml/kg (approximately 15,400 nig/kg)
            was reported in rabbits (Smyth et al., 1962).

         0  An inhalation exposure of 4,000 ppm (approximately  17,400  rtig/Ti3)  for
            four hours was lethal to 3 of 6 rats  (Smyth et al., 1962).

         0  During LD50 studies systemic toxic effects were observed predominantly
            in the liver and kidney (Wolf et al.,  1956) and central nervous system
            (Faustov, 1958).

         0  Other acute effects include irritation of the conjunctiva   (Wolf et al.,
            1956) and slight necrosis of the cornea  (Smyth et al., 1962).

    Long-term Exposure

         0  Liver and kidney effects were observed in rats (10 females/dose)
            exposed orally to ethylbenzene in olive oil for six months (Wolf
            et al., 1956).  Doses of 408 and 680 mg/kg/day caused increases in
            liver and kidney weights, and cloudiness and swelling of hepatocytes
            and renal tubular epithelium.  No effects were observed in rats
            exposed to 13.6 and 136 mg/kg/day.

         0  No chronic exposure studies were identified in the available  literature.

-------
   Ethylbenzene                                                 March  31, 1987

                                        -5-

   Reproductive Effects

        0  No studies on the effects of ethylbenzene on reproduction were located
           in the available literature.

   Developmental Effects

        0  Ethylbenzene did not elicit embryotoxicity, fetotoxicity or terato-
           genicity in inhalation studies at concentrations up to 1,000 ppm
           (4,348 mg/ra3) in rats and rabbits for 6 to 7 hours/day on days 1  to
           19 and 1  to 24 of gestation, respectively (Hardin et al., 1981).

        0  Female rats exposed at 1,000 ppm had increased liver,  kidney and
           spleen weights suggestive of maternal toxicity.  There was no maternal
           toxicity observed when the rats were exposed to 100 ppm of ethylbenzene.
           {Hardin et al.,  1981).

   Mutagenicity

        0  No mutagenic activity was detected in S_._ typhimurium strains TA98,
           TA100, TA1535, TA1537 following ethylbenzene exposure both with and
           without metabolic activation in plate assays at concentrations up to
           3 mg/plate (Florin et al., 1980;  Nestmann et al.,  1980).

        0  Dean et al. (1985) reported that ethylbenzene (0.2 to  2,000 ug/plate)
           did not induce mutations in bacteria, gene conversion  in  yeast or
           chromosome damage in rat liver (RL4)  epithelial cells.

        0  In the Drosophila recessive lethal test,  ethylbenzene  did not increase
           the frequency of recessive lethals (Donner et al.,  1979).

   Carcinogenicity

        0  Pertinent data on the carcinogenic potential of ethylbenzene were not
           identified in the available literature.  An NCI bioassay  is in the
           planning  stage.


V. QUANTIFICATION OF TOXICOLOGICAL EFFECTS

        Health Advisories (HAs) are generally determined for  One-day,  Ten-day,
   Longer-term (approximately 7 years) and Lifetime  exposures if  adequate data
   are available that identify a sensitive noncarcinogenic end point of toxicity.
   The HAs for noncarcinogenic toxicants are derived using the following formula:

                 HA  = (NOAEL or LOAEL) x (BW) =  	   /L (	   /L}
                        (UF) x (     L/day)
   where:
           NOAEL  or  LOAEL =  No-  or  Lowest-Observed-Adverse-Effect-Level
                            in mgAg  bw/day.

-------
Ethylbenzene                                                March 31, 1987

                                     -6-
                    BW = assumed body weight of a. child (10 kg) or
                         an adult (70 kg).

                    UF = uncertainty factor (10, 100 or 1,000), in
                         accordance with NAS/ODW guidelines.

             	 L/day = assumed daily water consumption of a child
                         (1 L/day) or an adult (2 L/day).

One-day Health Advisory

     No adequate dose-response data exist using the oral route of exposure
from which to calculate a One-day Health Advisory.   Therefore, the derivation
of the one-day level is based upon a 100 ppm (435 mg/m3) NOAEL identified in
18 human male volunteers following a single 8-hour  inhalation exposure as
conducted by Bardodej and Bardodejova (1970).   An inhalation absorption
efficiency of 64% is used,  based on data from that  study (Bardodej and
Bariodejova, 1970).

     The total absorbed dose and the One-day HA for a 10 kg child are
calculated as follows:

Step 1:  Determination of Total Absorbed Dose  (TAD)


             TAD = (435 mg/m3) (8 m3/day) (0.64) =  3UQ mg/kg/day
Step 2:  Determination of One-day HA

        One-day HA = (_31 .8 mg/kg/day) (10 kg) = 32 mg/L  (32000 ug/L)
                          (10) (1 L/day)
where:
        435 mg/m3 = NOAEL based on absence of effects in humans following
                    inhalation exposure.

         8 m3/day = assumed volume of air inhaled per daily 8-hour exposure.

             0.64 = absorption efficiency reported by Bardodej and Bardodejova
                    (1970).

            70 kg = assumed body weight of an adult.

            10 kg = assumed body weight of a child.

          2 L/day = assumed daily water consumption of an adult.

          1 L/day = assumed daily water consumption of a child.

               10 = uncertainty factor, chosen in accordance with NAS/ODW
                    guidelines for use with a NOAEL from a human study.

-------
 Ethylbenzene                                                March 31, 1987

                                      -7-

 Ten-day Health Advisory

      Because of the lack of appropriate exposure duration data,  the ten-day
 HA will be calculated from the One-day HA.  The One-day HA will be divided by
 10 to give estimated Ten-day HA values.  The resulting Ten-day HA for a child
 is as follows:

                  Ten-day HA = 32 m
-------
Ethylbenzene                                                March 31, 1987

                                     -8-


Step 1:  Determination of the Reference Dose (RfD)

                  RfD = (136 mg/kg/day) (5 )  ,= 0>097 mg/kg/day
                            (1,000)    (7)

where:

        136 mg/kg/day = NOAEL for absence of renal and hepatic effects in
                        rats exposed for 130 days.

                  5/7 = conversion of 5 days/week dosing regimen to continuous
                        7 days/week exposure pattern.

                1,000 = uncertainty factor, chosen in accordance with NAS/ODW
                        guidelines for use  with a NOAEL from an animal study
                        of less-than-lifetime duration.

Step 2:  Determination of the Drinking Water Equivalent Level (DWEL)

           DWEL = (0.097 mg/kg/day)(70 kg)  = 3.4 mg/L (3,400 ug/L)
                         (2 L/day)

where:

        0.097 mgA9/<3ay = RfD.

                  70 kg = assumed body weight of an adult.

                2 L/day = assumed daily water consumption of an adult.

Step 3:  Determination of the Lifetime Health Advisory

                  Lifetime HA =  (3.4 mg/L)   (20%) =0.68 mg/L

where:

         3.4 mg/L = DWEL.

              20% = assumed relative source contribution from water.

Evaluation of Carcinogenic Potential

     0   Because of the lack of data, an assessment of  the carcinogenic risk
         of ethylbenzene is not possible at  this time.

        The International Agency  for Research on Cancer has not classified
         ethylbenzene in any of its categories of carcinogenic potential.

     0   Applying the criteria described in  EPA's guidelines for assessment
         of carcinogen .risk  (U.S.  EPA,  1986), ethylbenzene is classified in
         Group D: not classified.  This category is for agents with  inadequate
         animal  evidence of carcinogenicity.

-------
      Ethylbenzene                                                 March 31, 1987

                                           -9-


  VI. OTHER CRITERIA, GUIDANCE AND STANDARDS

           0  The American Conference of Government Industrial Hygienists has
              recommended an occupational standard (TWA) in air and TLV of 100 ppm
              (435 mg/m3; ACGIH, 1980).

           0  EPA/ODW has proposed a RMCL of 0.68 mg/L (U.S. EPA, 1985e).


 VII. ANALYTICAL METHODS

           0  Analysis of ethylbenzene is by a purge-and-trap gas chromatographic
              procedure used for the determination of volatile aromatic organic
              compounds in water (U.S. EPA,  1985b).  This method calls for  the
              bubbling of an inert gas through the sample and trapping ethylbenzene
              on an adsorbant material.  The adsorbant material is heated to drive
              off ethylbenzene onto a gas chromatographic column.  The gas  chromato-
              graph is temperature programmed to separate the method  analytas which
              are then detected by the photoionization detector.  This method is
              applicable to the measurement  of ethylbenzene over a concentration
              range of 0.02 to 1500 ug/L. Confirmatory analysis for  benzene is by
              mass spectrometry (U.S. EPA,  1985c).  The detection limit for
              confirmation by mass spectrometry is 0.2 ug/L.


VIII. TREATMENT  TECHNOLOGIES

           0   Aeration appears to  offer the  best potential  for  removing ethylbenzene
              from contaminated water.  Ethylbenzene  has  a  high Henry's Law  Constant
              of 35 atm (U.S. EPA,  1985d).

           0   In an actual packed  aeration column (PAC) pilot testing program,
              ethylbenzene removal efficiencies ranged from 71.8 to >99.8%  (U.S.
              EPA,  1985d).  The column used  had a one foot  diameter and was  packed
              with Tripack packing material  (#2).  Influent concentrations of
              ethylbenzene ranged  from <1 to 200 ug/L.  Air-to-water  ratios  varied
              from 10:1  to 126:1.   Liquid loading rates  varied  from 12.7 to  50.9
              gpm/ft2.  Ambient water temperature was  70F.  Removal  efficiencies
              were >90%  for all test runs but one.  In this single exception, an
              efficiency of 71.8%  was obtained.  In this  test run the ethylbenzene
              concentration was high (200 ppb)  and the air-to-water ratio low -
              10:1  (U.S. EPA,  1985d).

           0   A  field test of  PAC  also was conducted  on water contaminated by a
              gasoline spill (Cummins,  1985).   Several benzene  derivatives including
              ethylbenzene were found in  this  water.   The aeration column was
              7.3 x 0.6  m and was  packed  to  5.5 m with 1  inch plastic saddles.
              Air-to-water ratios  of  from 8:1  to 88:1  were  used.   Ethylbenzene
              was decreased to below detection  (<0.5  ug/L)  whenever the air-to-water
              ratios  were 20:1  or  greater.   Ethylbenzene  was  detected if  lower
              air-to-water ratios  were  used.  A total  of  75 samples were  tested.

-------
Ethylbenzene                                                March 31,  1987

                                     -10-

     0  Decarbonators,  which can be considered as  modified aerators,  were used
        to remove synthetic organic contaminants including ethylbenzene at Water
        Factory 21  (U.S. EPA,  1985d).   The air-to-water ratio was 22:1.  Levels
        of influent ethylbenzene contamination were 0.067 and 0.23 ug/L.  The
        decarbonators removed 39.8 and 56.51% of the ethylbenzene, respectively.

     0  Granular activated carbon (GAG) also is at least partially effective
        in the removal of ethylbenzene from solution by adsorption.  Over two
        separate trial periods,  GAC was found to remove some of the ethylbenzene
        from contaminated drinking water.  At an influent concentration of
        0.06 ug/L,  45% of the ethylbenzene was removed.  When the influent
        was 0.07 ug/L,  17% was removed (McCarty et al., 1979).

     0  Application of PAC for ethylbenzene removal was tested at the Sunny
        Isles Water Treatment Plant (Florida)  (U.S. EPA,  1985d).   For  a
        14-month period, 7.1  mg/L PAC  was added to the water at the wellfield.
        For 3 of 5  samples analyzed, >99% of the ethylbenzene was removed;
        for 2 samples,  the removal rate was only 33%.

     0  In one study, conventional treatment was found to reduce  the ethyl-
        benzene in  water containing 0.7 ug/L by 43% (U.S. EPA,  1985d).

-------
    Ethylbenzene                                               March 31,  1987

                                         -1 1-


IX. REFERENCES

    ACGIH.   198.0.   American Conference of Industrial Government Hygienists.
         Ethylbenzene.   Documentation of the Threshold Limit Values.  4th ed.,
         p.   176.

    Amoore,  J.E.,  and E. Hautala.   1983.  Odor  as  an aid  to chemical safety;  odor
         threshold compared with Threshold Limit Values and volatilities  for  214
         industrial chemicals  in air  and water  dilution.   J.  Appl.  Toxicol.
         3:272-290.

    Angerer,  J., and G.  Lehnert.  1979.   Occupational chronic exposure  to solvents.
         VIII.  Phenolic compounds: Metabolites of alkylbenzenes  in man:  Simultaneous
         exposure  to ethylbenzene  and xylenes.   Int.  Arch.  Occup.  Environ. Health.
         43:145-150.

    Bardodej,  Z.,  and E. Bardodejova.  1970. Biotransformation of  ethylbenzene,
         styrene and alpha-methylstyrene in  man.   Am. Ind.  Hyg. Assoc.  J.
         31:206-209.

    Chin,  B.H.,  J.A. McKelvey,  T.R. Tyler, L.J. Calisti,  S.J.  Kozbelt and L.J.
         Sullivan.  1980.   Absorption,  distribution and excretion  of ethylbenzene,
         ethylcyclohexane  and  methylethylbenzene  isomers  in rats.   Bull.  Environ.
         Contain. Toxicol.   24:477-483.

    Cummins,  M.D.   1985.  Field evaluation of packed column stripping,  Pastrap,
         LA.   U.S. Environmental Protection  Agency,  Office  of Drinking  Water.

    Dean,  B.J.,  T.M. Brooks, G.  Hodson-Walker and  D.H.  Hutson.  1985.   Genetic
         toxicology testing of  41  industrial chemicals.   Mutat. Res.  153:57-77.

    Donner,  M.,  J. Maki-Paakkanen,  N. Norppa, M.  Sorsa  and  H.  Vaino.  1979.
         Genetic toxicology of  xylenes.   Mutat. Res.   74:171-172.

    Dutkiewicz,  T.,  and  H.  Tyras.   1967.  Study of the  skin absorption  of ethyl-
         benzene in man.  Br.  J. Ind. Med.   24:330-332.

    El  Masry,  A.M.,  J.N. Smith  and R.T.  Williams.   1956.  The  metabolism  of
         alkylbenzenes:  n-Propylbenzene and n-butylbenzene with  further  obser-
         vations on ethylbenzene.  Biochem.  J.   64:50-56.

    Engstrom,  J.,  and R. Bjurstrom.   1978.   Exposure  to xylene  and  ethylbenzene.
         II.   Concentration in  subcutaneous  adipose tissue.   Scand.  J.  Work Environ.
         Health.   4:195-203.

    Engstrom,  K.L.  1984.   Metabolism of inhaled  ethylbenzene  in  rats.  Scand. J.
         Work  Environ. Hlth.   10:83-87.

    Faustov, A.S.   1958. Toxicity of aromatic  hydrocarbons.   I.  Comparative
         toxicity  of some aromatic hydrocarbons.   II.  Some problems of the toxic-
         hygiene properties of  aromatic  hydrocarbons.  Tr.  Voronezh.  Gos. Med.
         Inst.  35:247-255;  257-262.   (Chem. Abstr. 54:25279d)

-------
Ethylbenzene                                                 March 31, 1987

                                     -12-
Florin, I., L. Rutberg, M. Curvall and C.R. Enzell.  1980.  Screening of
     tobacco smoke constituents for mutagenicity using the Ames test.  Toxi-
     cology.  18:219-232.

Hagemann,  J., and J. Angerer.  1979.  Biological monitoring in occupational
     ethylbenzene loading.  Kolloq., Ber. Jahrestag. Dtsch. Ges. Arbeitsmed.,
     19th.  pp. 421-425.  (Chem. Abstr. 94:196880)

Hardin, B.D.., G.P. Bond, M.R. Sikov, F.D. Andrew, R.P. Beliles and R.W. Niemeier<
     1981.  Testing of selected workplace chemicals for teratogenic potential.
     Scand. J. Work Environ. Health.  7{Suppl. 4):66-75.

Kiese, M., and W. Lenk.  1973.  w- and (w-1)-Hydroxylation of 4-chloropro-
     pionanilide by rabbits and rabbit liver microsomes.  Biochem. Pharmacol.
     22:2565-2574.

McCarty, P.L., D. Argo and M. Reinhard.  1979.  Operational experiences with
     activated carbon adsorbers at Water Factory 21.  JAWWA.  11:683-689.

Mihail, G., A. Zlavog, V. Anghelache and J. Bodnar.  1972.  Serum ornithine
     carbamoyltransferase, test for evaluating hepatic alterations caused by
     some industrial toxic substances.  Igiena.  21:267-276.  (Chem. Abstr.
     79:1036)

NCI.   1983.  National Cancer Institute.  National Toxicology Program 
     Toxicology Testing Program.  Chemicals on Standard Protocol:  Management
     Status.  June 15, 1983.

Nestmann,  E.R., E.G-H. Lee,  T.I. Matula,  G.R. Douglas and J.C. Mueller.
     1980.  Mutagenicity of constituents identified in pulp and paper mill
     effluents using the Salmonella/mammalian-microsome assay.  Mutat. Res.
     79:203-212.

Smyth, H.F., C.P. Carpenter, C.S. Weil, U.C. Pozzani and J.A. Stregel.
     1962.  Range-finding toxicity data.  List VI.   Am. Ind. Hyg. Assoc. J.
     23:95-107.

U.S. EPA. 1985a. U.S. Environmental Protection Agency.  Draft.  Drinking
     water criteria document for ethylbenzene.  Office of Drinking Water.

U.S. EPA.  1985b.  U.S. Environmental Protection Agency.  Method 503.1.  Volatile
     aromatic organic compounds in water by purge and trap gas chromatography.
     Environmental Monitoring and Support Laboratory, Cincinnati, Ohio 45268.

U.S. EPA.  1985c.  U.S. Environmental Protection Agency.  Method 524.1.  Volatile
     organic compounds in water by purge and trap gas chromatography/mass
     spectrometry.  Environmental Monitoring and Support Laboratory, Cincinnati,
     Ohio 45268.

U.S. EPA.  1985d.  U.S. Environmental Protection Agency.  (Draft) Technologies
     and costs for the removal of synthetic organic chemicals from potable
     water supplies.  Science and Technology Branch, CSD, ODW, Washington,
     D.C.

-------
Ethylbenzene                                                  March 31, 1987

                                     -13-
U.S. EPA.  1985e.  U.S. Environmental Protection Agency.  Proposed RMCL for
     SOCs, IOCS and Microbials.  Federal Register.  50(219):46936-47023.
     November 13.

U.S. EPA.  1986.  U.S. Environmental Protection Agency.  Guidelines for
     carcinogen risk assesment.  Federal Register.  51 {185) .-33992-34003.
     September 24.

Verschueren,  K.  1983.  Handbook of Environmental Data on Organic Chemicals.
     2nd ed.   Van Nostrand Reinhold Company, NY.  pp. 628-630.

Vinokurova,  M.I.  1970,  Combined effect of styrene,  butadiene and ethylbenzene
     on the functional indexes of the cardiovascular system.  Tr. Azerb.
     Nauchno.-Issled.  Inst. Gig. Tr. Prof. Zabol.  4:21-26.  (Chem.  Abstr.
     81:140347)

Westrick, J.J., J.W. Mello and R.F. Thomas.  1983.  The ground water  supply
     survey:  Summary of volatile organic contaminant occurrence data.
     EPA-ODW/TSD, Cincinnati, Ohio.

Wolf, M.A.,  V.K. Rowe, D.D. McCollister,  R.L.  Hollingsworth  and F. Oyen.
     1956.  lexicological studies of certain alkylated benzenes and benzene.
     Arch. Ind. Health.  14:387-398.

-------