March  31,  1987

                       820K87115

                                1,1-DICHLOROETHYLENE

                                  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 values 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 unit
   risk is usually derived from the  linear multistage model with 95% upper
   confidence limits.  This  provides a  low-bose estimate of cancer risk to
   humans 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  that are
   derived can differ by several  orders of magnitude.
                     U.S. Environmental Protection Agency
                     Region V, Library
                     230 South Dearborn Street
                     Chicago, Illinois  60604

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  1,1-Dichloroethylene                                             March 31, 1987

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         This Health Advisory is based on information presented in the Office
    of Drinking Water's Health Effects Criteria Document (CD) for the dichloro-
    ethylenes (U.S. EPA, 1984a).  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 ol
    Commerce, 5285 Port Royal Rd., Springfield, VA  22161,  PB #86-117785/AS.
    The toll-free number is (800) 336-4700; in the Washington, D.C. area:  (703)
    487-4650.
II. GENERAL INFORMATION AND PROPERTIES

    CAS No.  75-35-4

    Chemical structure
                                         Cl
                                         i
                                      C1-C=C-H
                                           I
                                           H
    Synonyms

         0  Vinylidene chloride, 1,1 -DCE, dichloroethene

    Uses

         0  1,1-Dichloroethylene has been used as a chemical intermediate and in
            the manufacture of polyvinylidene copolymers.

    Properties  (Irish, 1963; Windholz et al., 1976)
            Chemical Formula            '
            Molecular Weight                '       96.95
            Physical State (room temp.)            clear, colorless liquid
            Boiling Point                          31.5 °C
            Melting Point                          -122.2 °C
            Density
            Vapor Pressure                         591 torr (208C)
            Specific Gravity                       1.3
            Water Solubility                       250 mg/L (20°C)
            Log Octanol/Water Partition            5.37
              Coefficient
            Taste Threshold (water)
            Odor Threshold (water)
            Odor Threshold (air)                   2000-5500 mg/m3
            Conversion Factor
    Occurrence
          0   1,1-Dichloroethylene  (1,1 -DCE) is a synthetic chemical with no known
             natural sources  (U.S. EPA, 1983).

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     1,1-Dichloroethylene                                         March 31, 1987

                                          -3-
          0  Approximately 200 million pounds of 1,1-DCE were produced in 1980.
             The major use of 1,1-DCE is as a co-monomer in the production of a
             number of polymers.  Polymers of 1,1-DCE and vinyl chloride are used
             as food wrap (CEH,  1983).

          0  The major releases  of 1,1-DCE to the environment are during its
             production and its use in the manufacture of polymers.  Due to its
             volatile nature,  the majority of releases are expected to be to air.
             Small amounts of 1,1-DCE may be released to water and land in
             industrial effluents and from the disposal of solid wastes (U.S. EPA,
             1983).  1,1-Dichloroethylene may be a degradation product of trichloro-
             ethylene and perchloroethylene.  While laboratory studies are currently
             inconclusive, 1/1-DCE has been found to co-occur in ground water with
             trichloroethylene and tetrachloroethylene and their other degradation
             products, cis- and trans-1,2-dichloroethylene and vinyl chloride.

          0  There is relatively little information on the behavior of 1,1-DCE in
             the environment.   However, the behavior of this chemical has been
             estimated based upon the information on similar chlorinated compounds
             (U.S. EPA, 1979).  1,1-Dichloroethylene released to the atmosphere is
             expected to chemically degrade in hours;  when released to surface
             waters, it is expected to volatilize rapidly.  1,1-DCE is chemically
             stable in water and mobile in soils and is expected to migrate with
             ground water.  1,1-Dichloroethylene is not believed to bioaccumulate
             in plants or animals.

          0  Available data suggest that 1,1-DCE is not a common contaminant of
             drinking water.  It has not been reported to occur at levels higher
             than 0.1 ug/L in surface water.  However, 1,1-DCE has been reported
             to occur at levels  up to 40 ug/L in wells contaminated with other
             chlorinated solvents.

          0  No information is available on the occurrence of 1,1-DCE in food.
             While 1,1-DCE is used in the manufacture of food wrap, residual levels
             are expected to be  very low because of its high volatility.   Due to
             limited release and rapid degradation, little or no contamination of
             food by 1,1-DCE is  expected.

          0  1,1-Dichloroethylene contamination of air has been reported to occur
             in urban and suburban areas in the low ppt range.  Levels in th& ppb
             range have been reported in the areas where 1,1-DCE and its
             polymers are manufactured (U.S. EPA, 1983).


III. PHARMACOKINETICS

     Absorption

          8  1,1-Dichloroethylene is completely absorbed after gavage,  since 96 to
             100% of a single dose is excreted within 72 hours (Jones and Hathway,
             1978a; McKenna et al.,  1978b).

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    1,1-Dichloroethylene                                         March 31,  1987

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    Distribution

         0  Distribution in rats following a single oral dose of 25 mg of 1,1-DCE/kg
            resulted in high concentrations in the liver and kidneys after 30
            minutes  with more general distribution throughout other soft tissues
            after 1  hour (Jones and Hathway, 1978a).

         0  Single oral doses of 14c-1,1-DCE,  at i or 50 mg/kg,  were administered
            to rats  (McKenna et al.,  1978a,b).  At 72 hours  after dosing, the
            greatest percentage of radioactivity was found in the liver.

    Metabolism

         0  The metabolic end products  of  chlorinated ethylenes  are predominately
            alcohols and carboxylic acids.  The known metabolites of 1,1-DCE are
            chloroacetic acid, chloroacetyl chloride and dichloroacetaldehyde
            (Liebler and Guengerich,  1983; Liebler et al.,  1984).  Toxic inter-
          •  mediates that are formed  may interact with tissue macromolecules.
  Excretion
            The rate of excretion is relatively rapid,  since most of a dose is
            eliminated within the first 24-72 hours after administration (Jaeger
            et al.,  1977).   At low doses,  a greater percentage of the metabolites
            are eliminated  via renal and biliary excretion.  Carbon dioxide
            formed during metabolism is expired through the lungs.

            As maximal metabolic capacity is approached at the higher dose levels,
            proportionally  less of the compound is removed from the blood as it
            passes through  the liver.  As a result, increasing amounts of unchanged
            1,1-DCE are eliminated via the lungs (McKenna et al;  1977).
IV. HEALTH EFFECTS

    Humans
            At high concentrations (>_ 4000 ppm;  15,880 mg/m3),  inhalation of
            1,1-DCE results in rapid onset of CMS depression, with unconsciousness
            following if exposure is continued (Irish, 1963).

            Reports of effects on workers exposed to this chemical in combination
            with other vinyl compounds include liver function abnormalities,
            headaches, vision problems, weakness, fatigue and neurological sensory
            disturbances (NIOSH,  1979).
    Animals
    Short-term Exposure
            Reported oral LDSQS in adult rats range from 200 to 1800 mg/kg (NIOSH,
            1978? Ponomarkov and Tomatis, 1980).  Young or fasted rats are more
            sensitive to the acute effects of 1,1-DCE, with LD50s of approximately
            50 mg/kg (Andersen and Jenkins, 1977).

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1,1-Dichloroethylene                                           March 31,  1987

                                       -5-
       0  The oral LD5QS in the mouse and the dog were reported to be 200 mg/kg
          (Jones and Hathway,  1978b)  and 5750 mg/kg (NIOSH,  1978), respectively.

       0  The most sensitive end-point of 1,1-DCE toxicity is liver damage,
          ranging from fatty infiltration to necrosis (Reynolds et al.,  1975;
          Chieco et al., 1982).  In rats, after doses of 50 to 700 mg of
          1,1-DCE/k9»  tne liver toxicity of  1,1-DCE followed a complex dose-
          response pattern, with a threshold level, a rapid increase in effect
          and an extended plateau where increasing doses caused slight increases
          in effect (Andersen and Jenkins, 1977).

       0  After a 90 day continuous exposure to 1,1-DCE (189 mg/m3) liver and
          kidney lesions have been demonstrated  (Prendergast et al., 1967).

       0  Since glutathione depletion increases toxicity (Jaeger et al., 1974;
          Andersen et al., 1980), the acute toxicity of the chemical is probably
          the result of a toxic metabolite.

  Long-term Exposure

       0  As with acute exposure, the liver appears to be the principal target
          of 1,1-DCE toxicity following extended periods of exposure. Chronic
          exposure of rats to 0 to 200 ppm (0 to 26 mg/kg) in drinking water
          resulted in fatty changes and hypertrophy of liver cells in females
          and males at the highest dose (Rampy et al., 1977; Quast et al.,
          1983).

  Reproductive Effects

       0  In a three-generation rat reproductive study, Nitschke et al.  (1983)
          reported that, at concentrations of 0, 50, 100 or 200 "ppm  (0 to 26
          mg/kg) in the drinking water, 1,1-DCE did not affect rat reproductive
          capacity.

  Developmental Effects
                                          t
       0  At levels producing no maternal toxicity (inhalation; 20 ppm in rats
          and 80 ppm in rabbits and ingestion; 200 ppm in rats) 1,1-DCE did not
          produce teratogenic effects in rats or rabbits following exposure of
          dams during organogenesis (Murray et al., 1979).

  Mutagenicity

       0  With S-9 activation, 1,1-DCE was mutagenic in the Ames Salmonella
          test at concentrations of 3.3 x 10~4 to 3.3 x 10-2 M (Bartsch et al.,
          1975) or when exposed to an atmosphere containing 5% 1,1-DCE for 3
          hours (Simmon et al., 1977).  The chemical had no mutagenic activity
          in the absence of the S-9 fraction.

       0  1,1-Dichloroethylene was mutagenic to E. coli Ki2 at a concentration
          of 2.5 mM with, but not without, microsomal activation  (Greim et al.,
          1975).

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1,1-Dichloroethylene                                             March 31,  1987

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         0  In mammalian assay systems,  a mutagenic effect was not observed.
            Using the dominant lethal assay, it was reported that exposure to
            1,1-DCE at 55 ppm for 6 hr/day for 11  weeks (Short et al.,  1977) or
            to 10 to 50 ppm for 6 hr/day for 5 days (Anderson et al.,  1977) did
            not produce germinal mutation.  In addition, using V79 Chinese hamster
            ovary cells, exposed to 1,1-DCE at concentrations of 2 or 10%, Drevon
            and Kuroki  (1979) did not observe any adverse effects.

         0  1,1-Dichloroethylene binds with DNA to a slight degree in the liver
            and kidneys of both rats and mice after inhalation exposure to 10 or
            50 ppm for 6 hours.  However, massive  tissue damage also occurred.
            In mice, the kidneys seem to be a more sensitive indicator of tissue
            damage than the liver (Reitz et al.,  1980).

         0  The International Agency for Research on Cancer  (IARC) concluded that
            there is sufficient evidence to state  that 1,1-DCE is mutagenic
            (IARC, 1982).

         0  For a recent review of this  area,  the  reader is referred to the
            article by Jacobson-Kram  (1986).

    Carcinogenic!ty

         0  The results of most studies  of the carcinogenic potential of this
            substance fail to support a significant, treatment-related increase
            in tumor incidence (U.S.-EPA, 1984a).   No oral study .has resulted
            in a significant tumor response (NTP,  1982; Quast et al., 1983).
            Some, but not all, of the inhalation studies have reported significant
            tumor increases (e.g., mammary tumors in female rats and mice and
            kidney adenocarcinomas in mice) (Maltoni et al., 1985).

         0  1,1-Dichloroethylene was inactive as a whole mouse skin carcinogen
            when administered subcutaneously (Van Duuren et al., 1979).  It was
            active as a skin tumor initiator following several topical applications
            of phorbol ester as a promoter.
                                            V

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 formulas

                  HA -  (NOAEL or LOAEL)  X (BW) = 	 mg/L (	ug/L)
                         (UF) x (    L/day)
    where:
            NOAEL or LOAEL • No- or Lowest-Observed-Adverse-Effect-Level
                             in mg/kg bw/day.

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1,1-Dichloroethylene                                             March 31, 1987

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                        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

         The study by Chieco and coworkers (1981) has been selected to derive the
    One-day HA.   The authors reported that when 200 mg/kg of 1,1-DCE was given in
    water containing 0.5% Tween 80, the chemical caused only a slight increase in
    the plasma levels of alanine,  but not aspartate,  transaminase.  In addition,
    the pathological changes observed in the liver were limited to a few scattered
    microfoci of necrosis.  Accordingly, the 200 mg/kg is taken to be the LOAEL.

         The One-day HA for the 10 kg child is calculated as follows:

             One-day HA = (200 mg/kg/day) (10 kg) = 2.
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in the livers of both sexes exposed to the highest dose.  A NOAEL of 100 ppm
(10 to 12.6 mgAg) was identified.

     A Longer-term HA for the 10-kg child is calculated as follows:

       Longer-term HA = (10 mg/kg/day) (10 kg) = ^ .0   /L (1/000 ug/L)
                           (100) (1 L/day)

where:

        10 mg/kg/day = NOAEL based on the absence of liver effects.

               10 kg * assumed body weight of a child.

                 100 = uncertainty factor, chosen in accordance with NAS/ODW
                       guidelines foruse with a NOAEL from an animal study.

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


     A Longer-term HA for the 70-kg adult is calculated as follows:

       Longer-term HA = (10 mg/kg/day) (70 kg) = 3.5   /L (3 500 ug/L)
                           (100) (2 L/day)

where:

        10 mg/kg/day = NOAEL based on the absence of liver effects.

               70 kg - assumed body weight of an adult.

                 100 » uncertainty factor, chosen in accordance with NAS/ODW
                       guidelines foruse with a NOAEL from an animal study.

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

Lifetime Health Advisory

     The Lifetime HA represents that portion of an individual's total exposure
that is attributed to drinking water and is considered protective of noncar-
cinogenic adverse health effects over a lifetime exposure.  The Lifetime HA
is derived in a three step process.  Step 1 determines the Reference Dose
(RfD), formerly called the Acceptable Daily Intake (ADI).  The RfD is an esti-
mate of a daily exposure to the human population that is likely to be without
appreciable risk of deleterious effects over a lifetime, and is derived from
the NOAEL  (or LOAEL), identified from a chronic  (or subchronic) study, divided
by an uncertainty factor(s)*  From the RfD, a Drinking Water Equivalent Level
(DWEL) can be determined  (Step  2).  A DWEL is a medium-specific (i.e., drinking
water) lifetime exposure level, assuming 100% exposure from that medium, at
which adverse, noncarcinogenic health effects would not be expected to occur.
The DWEL is derived from the multiplication of the RfD by the assumed body
weight of an adult and divided by  the assumed daily water consumption of an

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1,1-Dichloroethylene                                             March 31,  1987

                                         -9-
    adult.   The Lifetime HA is determined in Step 3 by factoring in other sources
    of exposure, the relative source contribution (RSC).   The RSC from drinking
    water is based on actual exposure data or,  if data are not available, a
    value of 20% is assumed for synthetic organic chemicals and a value of 10%
    is assumed for inorganic chemicals*   If the contaminant is classified as  a
    Group A or B carcinogen, according to the Agency's classification scheme  of
    carcinogenic potential  (U.S.  EPA,  1986),  then caution should be exercised in
    assessing the risks associated with lifetime exposure to this chemical.

          The Lifetime HA can be  calculated from the 2-year chronic study in  rats
    (Quast et al., 1983).  1,1-Dichloroethylene, at nominal concentrations of 0,
    50,  100 or 200 ppm (0 to 20 mg/kg/day) in drinking water,  was administered to
    animals of both sexes.   No consistent treatment-related biochemical changes
    were observed in any parameter measured.   The only abnormal histopathology
    observed was mid-zonal  fatty  accumulation in the livers of both sexes
    receiving the highest dose.  No liver degeneration was noted.  A LOAEL of
    100 ppm (10 mg/kg) was  identified,  based  upon a trend towards increased fatty
    deposition in the liver.

         A Drinking Water Equivalent Level (DWEL) and Lifetime HA for the 70-kg
    adult are calculated as follows:

    Step 1:  Determination of the  Reference Dose (RfD)

                        RfD = (10 mg/kg/day)  = 0.01  mg/kg/day
                                 (1,000)

    where:

            10 mg/kg/day «  LOAEL  for hepatic  effects.
                   1,000 * uncertainty factor,  chosen in accordance with NAS/ODW
                           guidelines for use with a LOAEL from an animal study.

    Step 2:   Determination of  the  Drinking Water Equivalent Level  (DWEL)
                                           t
                DWEL - (0.01 ing/kg/day)  (70 kg) m 0.35 mg/L (350 ug/L)
                              (2 L/day)

    where:

            0.01  mgAg/day - 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 -  (0.35  mg/L) (20%) _ Q.007  mg/L (7 ug/L)
                                    (10)

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     1,1-Dichloroethylene                                         March  31,  1987

                                          -10-


     where:

             0.35 mg/L = DWEL.

                   20% = assumed relative  source contribution from water.

                    10 « additional  uncertainty factor  for  class  C carcinogens.

     Evaluation of  Carcinogenic Potential

          0   Qualitative and quantitative  assessment of the carcinogenic potential
             of 1,1-DCE is complicated  by  the fact that there is  only one  positive
             bioassay (Maltoni et al.,  1985) among  the  18 oncogenic studies  (U.S.
             EPA, 1985c).

          0   IARC (1982) reported that  the data were inadequate to assess  the
             carcinogenic potential  in  humans,  but that it  would  reevaluate  the
             assessment after reviewing the rat drinking water study  (Rampy  et al.,
             1977;  Quast et  al., 1983)  and the  NTP gavage bioassays  (NTP,  1982).
             At the present  time, this  has not been done.

          0   Applying the criteria described- in EPA's guidelines  for  assessment
             of carcinogenic risk (U.S. EPA, 1986), 1,1-dichloroethylene may be
             classified in Group C:  Possible human carcinogen.  Group C  includes
             agents with limited evidence  of carcinogenicity in animals  in the
             absence of human data.


 VI.  OTHER CRITERIA, GUIDANCE AND STANDARDS

          0   In June, 1984,  EPA proposed a Recommended Maximum Contaminant Level
             (RMCL) of zero  for  1,1-dichloroethylene in drinking  water (U.S. EPA,
             1984b).  In 1985, a RMCL of 7 was  promulgated  for 1,1-dichloroethylene.
             This value also was proposed  for the  MCL  (U.S. EPA,  1985a).

          0   In 1980, EPA estimated  a range of  excess cancer risks for lifetime
             exposure to 1,1-dichloroethylene when developing ambient water  quality
             criteria (U.S.  EPA, 1980a).   This  range was 23 ug/L, 2.3 ug/L and
             0.23 ug/L, respectively, for  risks of  10~4, 10~5 and 10~6,  assuming
             consumption of  2  liters of water and  6.5 grams of contaminated  fish
             per day by 70-kg adult.

          9   The National Academy of Sciences calculated a  chronic SNARL (Suggested-
             No-Adverse-Response-Level) of 100 ug/L, based upon non-carcinogenic
             effects only  (NAS, 1983).  The Academy identified a  NOAEL of  2  mg/kg
             from the 1982 NTP bioassay in mice.   An uncertainty  factor  of 100
             was  applied.  It was assumed  that  a 70 kg  adult consumes 2  liters of
	          water  daily and 20% of  the exposure of most individuals  would be
             from drinking water.  In addition, a  factor of 5/7 to correct from
             5- to  7-day/week exposure  was used.

          0   The  World  Health  Organization has  established  a guideline for 1,1-DCE
             in drinking water  of 0.3 ug/L,  set on evidence of carcinogenicity
             (WHO,  1984).

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       1,1-Dichloroethylene                                         March 31, 1987

                                            -11-
            0  The threshold limit value (TLV) for 1,1-DCE in occupational settings
               is 5 ppm (20 mg/m3) (ACGIH,  1982).

  VII. ANALYTICAL METHODS

            0  Analysis of 1,1-DCE is by a  purge-and-trap gas chromatographic procedure
               used for the determination of volatile organohalides in drinking water
               (U.S. EPA,  1985).   This method calls for the bubbling of an inert gas
               through the sample and trapping 1,1-DCE on an adsorbant material.
               The adsorbant material is heated to drive off the 1,1-DCE onto a gas
               chromatographic column.  This method is applicable to the measurement
               of 1,1-DCE over a  concentration range of 0.03 to 1500 ug/L.  Confirma-
               tory analysis for  1,1-DCE is by mass spectrometry (U.S. EPA, 1985b).
               The detection limit for confirmation by mass spectometry is 0.2 ug/L.


VIII.  TREATMENT TECHNOLOGIES

            0  Granular activated carbon (GAC) adsorption and aeration treatment
               technologies are available for the  removal of 1,1-DCE from water
               and have been reported to be effective.   Selection of individual or
               combinations of technologies to achieve chemical reduction must be
               based on a case-by-case technical evaluation and an assessment of the
               economics involved.

            0  Aeration has been  shown to be effective  in removing 1,1-DCE from
               water,  based upon  its carbon adsorption isotherm (Henry's Law
               Constant * 498 atm) and pilot and full-scale testing.   The chemical
               was removed successfully from contaminated ground water at 12-14°C in
               an EPA pilot packed tower aerator containing 18 feet of 1-inch plastic
               saddle packing (ESE, 1984).   The average percent removal varied with
               air-to-water volume ratio, from 90.6% to 99.99% at ratios of 5 to 80,
               respectively.  Similarly, the concentration of 1,1-DCE in contaminated
               well water decreased from 122 ug/L  to 4  ug/L (97%)  using diffused
               aeration (ESE,  1984).  Aeration was conducted in a pilot (1.5 inch
               diameter, 4-foot long) countercurrent glass column,  using a 10-minute
               contact time and an air-to-water ratio of 4.

            0  Air stripping is an effective,  simple and relatively inexpensive
               process for removing 1,1-DCE from water.  However,  the use of this
               process transfers  the contaminant directly to the air stream.  When
               considering use of air stripping as a traetment process, it is
               suggested that careful consideration be  given to the overall
               environmental occurrence, fate, route of exposure and various hazards
               associated with the chemical.

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    1,1-Dichloroethylene                                         March 31, 1987

                                       -12-


IX. REFERENCES

    ACGIH.   1982.   American Conference of Government Industrial Hygienists.
         TLVs.  Threshold limit values for chemical substances in work air.

    Andersen,  M.E., and L.R. Jenkins,  Jr.  1977.   Oral toxicity of 1,1-dichloro-
         ethylene in the rat:  Effects of sex, age and fasting.  Environ. Health
         Perspect.   21:157-163.

    Andersen,  M.E., O.E. Thomas,  M.L.  Gargas,  R.A. Jones and L.J. Jenkins, Jr.
         1980.  The significance of multiple detoxification pathways for reactive
         metabolites in the toxicity of 1,1-dichloroethylene.  Toxicol. Appl.
         Pharmacol.  52:422-432.

    Anderson,  D.   1977.  Dominant lethal studies  with the halogenated  olefins
         vinyl chloride and vinylidene chloride in male CD-1 mice.  Environ.
         Health Perspect.  21:71-78.

    Bartsch,  H.,  C. Malaveille,  R.  Montesano and  L. Tomatis.  1975.  Tissue-
         mediated mutagenicity of vinylidene chloride and 2-chlorobutadiene in
         Salmonella typhimurium.   Nature.  255:641-643.

    CEH. 1983.  Chemical Economics Handbook, Stanford Research Institute,
         Menlo Park, California.

    Chieco, P., M.T. Moslen and E.S. Reynolds.  1981.  Effect of administrative
         vehicle on oral 1,1-dichloroethylene toxicity.  Toxicol. Appl. Pharmacol.
         57:146-155.

    Chieco, P., M.T. Moslen and E.S. Reynolds*  1982.  Histochemical evidence that
         plasma ana^~mrtochondrial membranes are primary foci of hepatocellular
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1,1-Dichloroethylene                                         March 31, 1987

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1,1-Dichloroethylene                                         March 31, 1987

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