HALOETHERS
Ambient Water Quality Criteria
              Criteria and Standards Division
              Office of Water Planning and Standards
              U.S. Environmental Protection Agency
              Washington, D.C.

-------
                        CRITERION DOCUMENT



                            HALOETHERS



CRITERIA



                           Aquatic Life



     4-bromophenylphenyl ether



     For 4-bromophenylphenyl ether the criterion  to protect  fresh-



water aquatic life as derived using the Guidelines is  6.2  ug/1  as



a 24-hour average and the concentration should not exceed  14  ug/1



at any time.



     For saltwater aquatic life, no criterion for 4-bromophenyl-



phenyl ether can be derived using the Guidelines, and  there  are



insufficient data to estimate a criterion using other  procedures.



                           Human Health



     There are insufficient toxicological data to calculate



exposure criteria for the haloethers covered  in this document.

-------
Introduction
     Haloethers are compounds which contain an ether moiety
(R-O-R)  and halogen atoms attached to the aryl or alkyl
groups.   Chloroethers appear to be the most important halo-
ethers used commercially and can be divided into two cate-
gories,  alpha- and non-alpha-chloroethers (EPA, 1975).
Chloromethyl methyl ether (CMME) is the only alpha haloether
of commercial significance and is used primarily in the
                                                         »
synthesis of strong base ion exchange resins used in water
conditioning and for chemical separation processes.  However,
CMME preparations are usually contaminated with 1 to 8 per-
cent bix(chloromethyl) ether (BCME) which has been demonstrat-
ed to be a potent carcinogen.
     The beta-chloroethers are widespread environmental
contaminants.  It has been suggested that they are: produced
or may be formed as by-products in sizable quantities, releas-
ed to and appear to persist in the environment, can pass
through drinking water treatment plants, and may be carcino-
genic.  Bis(2-chloroethyl) ether  (BCE) is used as a dewaxing
agent for lubricating oils and is a useful solvent for naph-
thenic components  (Fairhall, 1949; Jacobs and Scheflan,
1953; Pollard and Lawson, 1955; Mervart, et al. 1960).
BCE has also been used to separate butadiene from butylene
(Lurie,  1965).  The second major use of bis(2-chloroethyl)-
ether is in the textile industry as a cleaning agent, a
wetting  agent and penetrant in combination with diethylene
glycol,  sulphonated oils, etc.  (Browning, 1953; Jacobs and
Scheflan, 1953; Allen, 1956).  The compound generally is
                            A-l

-------
a good solvent for tars, fats, waxes, oils, resins and pec-
tins, and will dissolve cellulose esters when used with
10 to 30 percent ethanol (Fife and Reid, 1930).
     Bis(2-chloroisopropyl) ether is an excellent solvent
and extractant for fats, waxes, and greases.  It also finds
use as a cleaning and spotting agent as well as an additive
to paint and varnish removers  (Hake and Rowe, 1963; Lurie,
1965).
     The alpha-haloethers are more reactive than beta-halo-
ethers due to the two electronegative atoms (oxygen and
halogen) which are bonded to the same carbon (Summers, 1955).
This difference in reactivity is evident by the different
rates of hydrolysis.  The most commercially significant
haloethers are the chloroethers.  Chlorine substitution
on ethers tends to increase their density, boiling point,
and odor while decreasing their flammability and altering
their solubility properties.  The fluorine substituted com-
pounds are much more volatile than their chlorinated ana-
logues  (EPA, 1975).
     The haloethers exist within a wide range of physical
properties.  For example, boiling points may range from
43.2°C  (2,2,2-trifluroethyl vinly ether) to 310°C (4-bromo-
phenylphenyl ether) (Lurie, 1965).  Melting points can range
from 103.5°C (chloromethyl methyl ether) to -3°C (chloro-
methyl phenyl ether) (Hawley, 1971).  The haloethers are
very soluble in benzene, carbon tetrachloride, and acetone
(Scheflan and Jacob, 1953)  and miscible in all oils (Lurie,
1965).
Table 1 lists the physical properties of some haloethers.
                               A-2

-------
             TABLE 1



Physical Properties of Haloethecs
Ether
bis (chloromethyl)
bis (2-chloroethyl)
(Chlorex)
bis (2-chlorisopropyl)
bis (2-chloroethoxy)
methane
Chloromethyl methyl
2- (2-chloroethoxy) ethyl
•f 2-chloroethyl
co
dichloromethyl methyl
dichloromethyl chloro-
methyl
bis (dichloromethyl)
tr ichloromethyl methyl
trichloromethyl
dichloromethyl
1-chloroethyl ethyl
2-chloroethyl ethyl
bis (1-chloroethyl)
Structure
(C1CH2)20
(C1CH2CH2)20
CH3
(C1CH2CH) 2O
(C1CH2CH20)2CH2
C1CH2OCH3
C12CHOCH3
C12CHOCH2C1
C12CHOCHC12
C13COCH3
C13COCHC12
CH3CHC10C2H5
(CH,CHC1),O
-3 ^
Boiling Melting
Point Point
(deg.C) (deg.C)
105 -41.5
178 -46.7
187.3 -96.8 to 99.8
218.1 -32.8
61 -103.5
84.5
129
143
106-110.5
159
2857mm
106
113
d20/4
1.315
1.2199
1.1127
1.234
1.0605
1.270
1.46430°C
1.558 30°C
1.4391

0.9495
0.9945
1.10625°C
Vapor Solubility
Pressure in water
(mm Hg) (g/iO)
0.7320°C 1.07
0.71-0.8520 C 0.17








-------
                                           TABLE 1  (continued)
Ether
bis (2-bromoethyl)
bis (2-chloropropyl)
bis (3-chloropropyl)
bis (4-chlorobutyl)
2-chloroethyl vinyl
•f chloromethyl ethyl
chloromethyl phenyl
2,2-dichloro-l,l-
difluoroethyl methyl
(raethoxyflurane)
2,2,2-tnfloroethyl
vinyl
(fluoroxene or
fluoromar)
Structure
(BrCH2CH2)20
(CH3CHC1CH2)20
(C1CH2CH2CH2)2O
(C1CH2CH2CH2CH2)20
C1CH2CH2OCH=CHH2
C1CH2OCH2CH3
C1CH2OC6H5
CHC12CF2OCH3
CP3CH2OCH=CH2
Boiling Melting
Point Point
{deg.C) (deg.C)
11532mm
188
215745nun
84-865.5°C
109 -70
84
88-90 - 3
104 -35
43.2
Vapor
Pressure
d20/4 (nun Hg)
27°c
1.8227// (-
1.109
1.14020/20
25°C
1.0691" C
1.0493
1.0322°4

1.4262
1.13 286
Solubility
in water
(g/iO)



0.6



0.4
Lune, 1965; Allen, 1956; Tschamler, 1950; Krentz, 1963; Hake and Roe, 1963

-------
                         REFERENCES
Allen, H. 1956. Safety hazards on some newer fine chemicals.
Chem. Prod. Chem. News. 19: 482.

Browning, E. 1953. Beta, beta-dichloroethyl ether. In Toxi-
city of Industria Organic Solvents. Chemical Publishing
Co., Inc., N.Y. p. 266.

Fairhall, L.T. 1949.  Dichloroethyl ether. In Industrial
Toxicology. Willis and Wilkins Co., Baltimore.

Fife, H.R., and E.W. Reid.  1930. New industrial solvents:
ethylene dichlor dichloroethyl ether, and disopropyl ether.
Industr. Engr. Chem. 22: 513.

Hake, C.L., and U.K. Rowe.  1963. Ethers. In Industrial Hygiene
and Toxicol. 2nd ed., ed. F.A. Patty. Interscience Publishers,
N.Y. 2: 1655.

Hawley, G.G. 1971. The Condensed Chemical Dictionary, 8th
ed. Van Nostrand, Reinhold-Co., New York.

Jacobs, M.B., and L. Scheflan. 1953. Oil- and water-repelling
substances. Ger. Offen. 2,247,111 24 pp.

Krantz, J.C., Jr. 1963. Anesthetics. Kirk-Othmer Encyclopedia
ot Chemical Technology, Vol. 2, 2nd ed., John Wiley and
Sons, Inc., N.Y. 2: 393.
                              A-5

-------
Lurie, A.P. 1965. Ethers. Kirk-Othmer Encyclopedia of Chemical
Technology Vol. 8, 2nd ed. John Wiley and Sons, Inc., N.Y.

Mervart, Z., et al. 1960. Economic analysis of the effect
of solvent characteristics on the isolation of 1,3-butadiene
by extractive distillate. Chem. Prumysl. 10j 132.

Pollard, W.R., and J.V. Lawson. 1955. Corrosion rates. Ind.
Eng. Chem. 47.

Scheflan, L., and H.B. Jacobs. 1953. The Handbook of Solvents.
Van Nostra Co., Inc., New York and London.

Summers, L. 1955. The alpha-haloalkyl ethers. Chem. Rev.
55: 301.

Tschmaler, H. 1950. Chlorex  (Bis(2-chloroethyl)ether). Osterr.
Chem. Atg. 51: 145.

U.S. EPA. 1975. Investigation of selected potential environ-
mental contaminants: haloethers. NTIS, Off. Tox. Subst.,
Springfield, Virginia^
                              A-6
                                                               I.J

-------
AQUATIC LIFE TOXICOLOGY*



                       FRESHWATER ORGANISMS



Introduction



     The only toxicity data for haloethers, other  than  for  those



compounds discussed in the criterion document for  chloroalkyl



ethers, are for 4-bromophenylphenyl ether and the  bluegill,  fat-



head minnow/ and Daphnia magna.



Acute Toxicity



     The bluegill has been exposed to 4-bromophenylphenyl ether



and the unadjusted 96-hour LC50 is 4,940 ug/1 (Table  1).  When



this result is adjusted for test conditions and  species sensi-



tivity, a Final Fish Acute Value of 690 ug/1 is  obtained.



     Daphnia magna is more sensitive than the bluegill  with  an



unadjusted 48-hour EC50 of 360 ug/1 (Table 2).   The Final Inver-



tebrate Acute Value for 4-bromophenylphenyl ether  is  14 ug/1 and



this also is the Final Acute Value.
*The reader is referred to the Guidelines for Deriving Water



Quality Criteria for the Protection of Aquatic  Life  [43  FR  21506



(May 18, 1978) and 43 FR 29028 (July 5, 1978)]  in  order  to  better



understand the following discussion and recommendation.   The  fol-



lowing tables contain the appropriate data that were  found  in the



literature, and at the bottom of each table for the calculations



for deriving various measures of toxicity as described in the



Guidelines.
                             B-l

-------
Chronic TOxicity



    A chronic value for 4-brcmophenylphenyl ether, 61 ug/1, is



derived from an embryo-larval test with the fathead minnow in which



adverse effects on survival and growth were observed (Table 3) (U.S.



EPA, 1978).  After division by the species sensitivity factor (6.7),



a Final Fish Chronic Value of 9.1 ug/1 is derived.  Since no other



chronic value for an invertebrate or plant species or a Residue



Limited Toxicant Concentration is available, 9.1 ug/1 is also the Final



Chronic Value.
                                  B-2

-------
CRITERION FORMULATION

                     Freshwater-Aquatic Life

Summary of Available Data

     The concentrations below have been rounded to  two  significant

figures.
                                                           i
4-bromophenylphenyl ether

     Final Fish Acute Value = 690 ug/1

     Final Invertebrate Acute Value = 14 ug/1

          Final Acute Value = 14 ug/1

     Final Fish Chronic Value = 9.1 ug/1

     Final Invertebrate Chronic Value = not available

     Final Plant Value = not available

     Residue Limited Toxicant Concentration = not available

          Final Chronic Value = 9.1 ug/1

          0.44 x Final Acute Value = 6.2 ug/1

     The maximum concentration of 4-bromophenylphenyl ether  is  the

Final Acute Value of 14 ug/1 and the 24-hour average concentration

is 0.44 times the Final Acute Value.  No important  adverse effects

on freshwater aquatic organisms have been reported  to be  caused by

concentrations lower than the 24-hour average concentration.

     CRITERION:  For 4-bromophenylphenyl ether the  criterion  to

protect freshwater aquatic life as derived using the Guidelines is

6.2 ug/1 as a 24-hour average and the concentration should not

exceed 14 ug/1 at any time.
                             B-3

-------
0)
I
                              Table  1.  Freshwater fish acute values for haloethers  (U.S. EPA, 1978)


                                                                                          Adjusted
                                   Bioaseay  Test      Chemical       Time      LCbu      Lcbo
           Organism                M^t-nod*   Conct**   Description    tfera)
           Blueglll.                  S        U     4-Bromophenyl-    96       4,940      2,700
           Lepomts macrochirua                        phenyl ether



           *  S • static

           ** U - unmeasured

              Geometric mean of adjusted  values:  A-Bromophenylphenyl ether *• 2,700 Mg/1     ^ S  • 690 pg/1

-------
CD
I
U1
                            Table  2   Freshwater invertebrate acute values for haloethers (U.S. EPA, 1978)


Organism
Cladoceran,
Daphnia magna

Bioassay Test Chemical
Method* Cone,** Description
S U 4-Bromophenyl-
phenyl ether

Time
itllB)
48


LCbU
(uq/1)
360

Adjusted
LC50
(uq/1)
300

         *  S = static

         ** U = unmeasured

            Geometric mean of adjusted  values:  4-Bromophenylphenyl ether = 300 ug/1

-------
                        Tafcle  3   Freshwater fish chronic values for haloethers (U.S. EPA. 1978)


                                                           Chronic
                                                 Limits     Value
          Organism                     Test*     (ug/il     (ug/il


                                     4-BromophenylphenyI  ether


          Fathead  minnow.               E-L        89-167       61
          Pimephales promelas
         *  E-L = embryo-larva

            Geometric mean of chronic values -  61  pg/1    g—j =9.1  pg/1


            Lowest chronic value - 61 Mg/1
CTv

-------
CRITERION FORMULATION



                      Saltwater-Aquatic Life



Summary of Available Data



     No appropriate data are available for saltwater organisms and



any haloether other than those discussed in the criterion document



for chloroalkyl ethers.



     CRITERION:  No saltwater criterion can be derived  for any



haloether using the Guidelines because no Final Chronic Value for



either fish or invertebrate species or a good substitute for



either value is available, and £here are insufficient data to



estimate a criterion using other procedures.
                              B-7

-------
                          HALOETHERS



                          REFERENCES







U.S. EPA. 1978.  In-depth studies on health and environmental



impacts of selected water pollutants.  U.S. Environ. Prot.



Agency, Contract No. 68-01-4646.
                               B-8

-------
Mammalian Toxicology and  Human  Health Effects

I.    Introduction

     The EPA is  currently charged with establishing water quality criteria

for halogenated  ethers.  This document covers chlorinated aromatic ethers

including:

              chlorophenyl phenyl ethers
              bromophenyl phenyl ethers
              polychlorinated diphenyl ethers

A separate document in this series, entitled "Chloroalkyl ethers," covers

the following compounds:

              bis(chloromethyl)ether
              bis(2-chloroethyl)ether
              2-chloroethyl vinyl ether
              bis(2-chloroisopropyl)ether
              bis(2-chloroethoxy)methane
                                  C-l

-------
II.  Exposure



     A.   Ingestion



          1.   Water



               Qualitative identifications of several haloethers in raw and



finished water have been reported.  This information is summarized in Table 1.



The nomenclature used in specifying some haloethers creates a certain amount



of confusion in evaluating these monitoring data.  For instance, in Table 1,



pentachlorophenoxy methyl ether is probably the same as pentachlorophenyl



methyl ether.  The names used in Table 1 are those given in the various



references cited.



               Shackelford and Keith  (1976) have compiled information on the



frequency of organic compounds identified in water.  This information was



taken from both the published literature and unpublished results of survey



analyses from EPA Regional Laboratories and Research Laboratories.  Although



actual levels of the haloethers in waters are not specified, a breakdown is



given of the various types of waters  found to be contaminated.  This infor-



mation is presented in  Table 2.



               The study by Ewing and coworkers  (1977) is based on the anal-



ysis of 204 water samples collected from fourteen heavily industrialized river



basins.  As indicated in Table 1, pentachlorophenyl methyl ether was found in



12 samples  (5.88%), with other chlorophenyl ethers found less frequently.  As



Indicated above, the reports of "pentachlorophenoxy methyl ether" probably



refer to pentachlorophenyl methyl ether.  The studies by Friloux (1971) and



the U.S. Environmental  Protection Agency (1972) both summarized in Table 1,



were conducted in the New Orleans area.
                                  C-2

-------
           Table 1.  Haloethers Qualitatively Identified in Water
                     (see text for details)
                         Reference
        Haloether
                                           *
                                           vO
                                           a\
                                           1
                                           •a
                                           o
                                           Jl
                                           CJ
                                           5
                                           en
       ff
      o
      l-l
      •H
      £
                 CO
                  •
                 S3
Bromophenyl phenyl ether
Bis(4-chlorophenyl)ether
Dichlorophenyl chlorophenyl ether
2,4,4'-Trichloro-2'-hydroxy-
  dlphenyl ether
Dichlorophenyl methyl ether
Trichlorophenyl methyl ether
Tetrachlorophenyl methyl ether
Fentachlorophenyl methyl ether
Pentachlorophenoxy methyl ether
 5
 2
 2
10
 1
 5
 1
12
 2
 Frequency of occurrence.
                                   C-3

-------
       Table 2.  Frequency Haloethers  Identified  in Various
                 Types of Water (Shackelford  and  Keith, 1976)
                                    Water  Type Contaminated
FDW River Raw Water
Bromophenyl phenyl ether 3 2
Bis (4-chlorophenyl) ether
Dichlorophenyl chlorophenyl ether
2,4,4' -Tr ichloro-2 ' -hydroxy-
diphenyl ether
Pentachlorophenyl methyl ether 331
Effluent
CHEM RS
2
2
1
1
from:
STP
2
 Key

FDW - Finished drinking water
G8SK m Chemical plant
RS » Raw sewage
STP - Sewage treatment plant
                             C-4

-------
               In the 1975 National Organics Reconnaissance



Survey by the U.S. Environmental Protection Agency, no halo-



ethers were found in the waters of Miami, Florida; Seattle,



Washington; Ottumwa, Iowa; or Cincinnati, Ohio  (U.S. EPA,



1975).



          2.    Food



               No monitoring data have been found on the



levels of haloethers in food.



     A bioconcentration factor (BCF) relates the concentra-



tion of a chemical in water to the concentration in aquatic



organisms, but BCF's are not available for the  edible portions



of all four major groups of aquatic organisms consumed in
  »


the United States.  Since data indicate that the BCF for



lipid-soluble compounds is proportional to percent lipids,



BCF's can be adjusted to edible portions using  data on percent



lipids and the amounts of various species consumed by Americans,



A recent survey on fish and shellfish consumption in the



United States (Cordle et al., 1978) found that  the per capita



consumption is 18.7 g/day.  From the data on the nineteen



major species identified in the survey and data on the fat



content of the edible portion of these species  (Sidwell,



et al., 1974), the relative consumption of the  four major



groups and the weighted average percent lipids  for each



group can be calculated:
                               C-5

-------
                          Consumption        Weighted Average
          Group             (Percent)          Percent Lipids
Freshwater fishes             12                    4.8
Saltwater fishes              61                    2.3
Saltwater molluscs             9                    1.2
Saltwater decapods            18                    1.2
Using the percentages for consumption and lipids for each
of these groups, the weighted average percent lipids is
2.3 for consumed fish and shellfish.
     Neither measured steady-state bioconcentration factors
{BCF) nor laboratory data (octanol-water partition coefficient)
are available for estimation of BCF at this time.
     B.   Inhalation
          No monitoring  information is available on the
levels of any chloroethers  in ambient air.
     C.   Dermal
          Because of the lack of monitoring data, no evalua-
tion of the importance of dermal exposures can be made for
the haloethers.
                               C-6

-------
III. Pharmacokinetics



     No information has been encountered in the pharnacokinetics of the



haloethers under review.
                                   C-7

-------
IV.  Effects



     1.   Acute, Subacute, and Chronic



          The acute and subacute oral toxlcity of various chlorinated phenyl



ethers is summarized in Tables 3 and 4.  Because of the lack of experimental



detail presented in this summary of unpublished data by Hake and Rove (1963)



these results are difficult to interpret.  However, the reported results on



"highly purified" pentachlorophenyl ether compared to the other pentachloro-



phenyl ether suggest that Impurities may be major toxic constituents.



          Hake and Rowe (1963) report that "small amounts" of hexachloro-



diphenyl ether may cause acneform dermatitis in man.



     2.   Joint Action with Other Toxicants



          No Information is available.



     3.   Teratogenicity



          Ho information is available.



     4.   Mutagenicity



          No information is available.



     5.   Carcinogenicity



          No Information is available.
                                  C-8

-------
Table 3.  Chlorinated Phenyl Ethers  Summary  of  Single-Dose
          Oral Feeding Studies  on Guinea Pigs  (Hake and
          Rowe, 1963)
Total Number
of Chlorines
1 x Cl
2 x Cl
3 x Cl
4 x Cl
5 x Cl
6 x Cl
After 4
Lethal dose
(mg/kg)
700
1,300
2,200
3,000
3,400
3,600
days
Survival
dose (mg/kg)
200
400
400
400
1,800
400
After
Lethal dose
(mg/kg)
600
1,000
1,200
50
100
50
30 days
Survival
dose (mg/kg)
100
50
200
0.5
5
5
                         C-9

-------
        Table A.   Chlorinated Phenyl  Ethers:  Results of Repeated Oral
                  Feeding of Rabbits  (Hake and Rove, 1963)
Total
Number of
Chlorines
1
2
3
4
5
6
Dose
(mg/kg)
100
100
100
50
10
50
5
50
100**
10**
1**
5
1
0.1
Number of
doses
19
19
5
20
20
4
20
8
20
20
20
8
20
20
Number
days
29
29
12
29
29
10
29
21
29
29
29
10
28
28
of Effect
None
Mild liver injury
Death
Slight liver injury
No effect
Death
Severe liver injury
Death
Moderate liver injury
No growth
Slight liver injury
No effect
Death
Severe liver injury
No effect
 Animals dosed 5 days/week x 4 weeks unless  death intervened.  Vehicles not
 specified.
**
  Highly purified pentachlorophenyl ether.
                                  C-10

-------
V.   Criterion Rationale


     A.   Existing Standards

          The Occupational Safety and Health Administration (38 FR 23540) has
                                             2                        '
set a time-weighted average value of 500 yg/m  for the following aromatic

chloroethers in the air of the working environment:  monochlorophenyl phenyl

ether, dichlorophenyl phenyl ether, tricolorophenyl phenyl ether, tetrachloro-

phenyl phenyl ether, and pentachlorophenyl phenyl ether.  This value has also

been adopted by the American Conference of Governmental and Industrial

Hygienistd (ACGIH, 1974).  The standard is designed to prevent the formation


of chloracne in exposed workers.

     B.   Current Levels of Exposure

          As detailed in Section II, only limited information is available on

the extent of human exposure to haloethers in water and no information is

available on ambient levels of haloethers in air or food.  Quantitative

estimates of human exposure cannot be made.

     C.   Special Groups at Risk

          Individuals working with haloethers or living in areas where these

haloethers are produced are probably at greater risk than the general popu-

lation.


     D.   Basis for the Standard

          As indicated in Section V.A., the TLV for chlorophenyl phenyl  ethers

           2
is 500 jjg/m .  By a process analogous to that used by Stokinger and Woodard

(1958), this standard could be used to calculate a water criterion.  However,

since the TLV for these compounds is based on preventing chloracne, rather

than chronic toxicity, such a calculation would not be appropriate.
                                    C-ll

-------
          There are not sufficient toxicologic data to calcu-
late exposure criteria for other haloethers covered in this
document.
                              C-12

-------
                                  REFERENCES


AC6IH (American Conference of Governmental Industrial Hygienlsts) (1974),
     Documentation of the Threshold Limit Values, 3rd Edition, 2nd Printing.

Eving, B.B., E.S.K. Chian, J.C. Cook, C.A. Evans, P.K. Hopke, and
     E.G. Perkins (1977), Monitoring to Detect Previously Unrecognized
     Pollutants in Surface Waters, EPA 560/6-77-015, 75 pp.

Friloux, J. (1971), "Petrochemical Wastes as a Pollution Problem in the Lower
     Mississippi River," Paper submitted to the Senate Subcommittee on Air
     and Water Pollution, April 5.

Hake, C.L. and V.K. Rowe (1963), "Ethers," in Industrial Hygiene and Toxicology,
     2nd Edition, Patty, F.A. (ed.), Interscience Publishers, New York, ,2:1655-
     1718.

Rosen, A.A., R.T. Skeel, and M.B. Ettinger (1963), "Relationship of River
     Water Odor to Specific Organic Contaminants," J. Water Pollut. Contr.
     Fedr., .35:777-782.

Shackelford, W.M. and L.H. Keith (1976), Frequency of Organic Compounds
     Identified in Water, EPA-600/4-76-062, U.S. Environmental Protection
     Agency, Athens, GA., 626 pp.

Stoklnger, H.E. and R.L. Woodward (1958), "Toxlcologlc Methods for Establishing
     Drinking Water Standards," J. Amer. Water Works Assn., 50;515.

U.S. Environmental Protection Agency (1972), "Industrial Pollution of the
     Lower Mississippi River in Louisiana," Region VI, Dallas, Texas,
     Surveillance and Analysis Division.

U.S. Environmental Protection Agency (1975), Preliminary Assessmei £ of Sus-
     pected Carcinogens in Drinking Water;  Interim Report to Coiu cess,
     Washington, D.C.
                                    C-13

-------