United States
                Environmental Protection
                Agency
Environmental
Research Laboratory
Athens GA 30613
                Research and Development
EPA/600/S3-91/004  Mar. 1991
EPA       Project Summary
                Chemical-Specific
                Parameters for Toxicity
                Characteristic  Contaminants
                J. Jackson Ellington, Chad T. Jafvert, Heinz P. Kollig,
                Eric J. Weber, and N. Lee Wolfe
                   Acid, base, and neutral hydrolysis
                rate constants and partition coefficients
                are given for 44 toxicity characteristic
                contaminants.  Both calculated and
                laboratory-determined octanol/water
                partition coefficient (K.J and organic-
                carbon-normalized partition coefficient
                (K.J values are included. Log K,, values
                were calculated at pH 7 for ten ionlzable
                acids and one ionizable base.
                   This Project Summary was devel-
                oped by EPA 'a Environmental Research
                Laboratory, Athens, GA,  to announce
                key findings of the research project that
                Is fully documented In a separate report
                of the same title (see Project Report
                ordering Information at back).

                Introduction
                   Assessment of potential risk posed to
                humans by man-made chemicals in the
                environment requires the prediction of en-
                vironmental concentrations of those
                chemicals under various  environmental
                reaction conditions. Whether mathematical
                models or other assessment techniques
                are employed, knowledge  of equilibrium
                and kinetic constants (fate constants) is
                required to predict the transport and trans-
                formation of these chemicals.
                   Under Section 301 of  the Resource
                Conservation and Recovery Act (RCRA),
                EPA's  Office of Solid Waste (OSW) has
                identified wastes that may pose a sub-
                stantial hazard to human health and the
                environment. RCRA requires that EPA
                develop and promulgate criteria for identi-
                fying and listing hazardous  wastes, taking
                into account, among other factors, persis-
                tence and degradability in the environment.
   In 1986, OSW proposed additions to
the list of chemicals regulated under the
Toxicity Characteristic section of RCRA. A
land disposal decision model developed at
the Environmental Research Laboratory in
Athens, Georgia (ERL-Athens) was applied
to  determine maximum  permissible
leachate concentrations resulting from the
Toxicity Characteristic Leachate Procedure
for the additional chemicals. This report
includes hydrolysis rate constants and
sorption equilibrium constants for 44 "tox-
icity characteristic" contaminants.

Hydrolysis
   In general, hydrolysis is a bond-mak-
ing, bond-breaking process in which a mol-
ecule, RX, reacts with water forming a new
R-O bond and cleaving a R-X bond  in the
original molecule. One possible pathway is
by a direct displacement of X" with HO" as
shown in Equation 1.
   RX + HO'-* ROX +X"
(1)
   The detailed mechanisms of hydrolytic
processes are well defined and have been
shown to involve the formation of interme-
diates such as protonated species, anions
and carbonium tons, as well as combina-
tions of these intermediates.
   In general, hydrolysis of organic chemi-
cals in water under pH-buffered conditions
is first-order in the  concentration of the
organic species ([RX]), where the rate of
hydrolysis (d [RX] / eft) is proportional to the
concentration of pollutant RX:
   d[RX]/dt = -kaM(RX\         (2)
where k „„, is the observed pseudo-first-
order disappearance rate constant.

          ^9 Printed on Recycled Paper

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   For abiotic hydrolysis, the general ex-
pression for ft ob, is given by:

                                   (3)
where /ca and k^ are the specific acid and
base second-order rate constants, respec-
tively; kn is the neutral hydrolysis rate con-
stant; and /CHA and /rA are the general acid
and base catalyzed hydrolysis rate con-
stants, respectively. In Equation 3, [H*] and
[OH-] are the hydrogen and hydroxyl  ion
concentrations, respectively, and [HA] and
[A~] are the concentrations of the Ah pair of
general  acids and bases  in the reaction
mixture.
   Values for k,,  k^, and kn at 25° C
reported in Table 1  can be used to calcu-
late k^ at a given pH  using Equation 3.

Partition Coefficients
   Partitioning between water and natural
soils,  sediments and  aquifer materials is
an important process affecting transforma-
tion rates, toxicity, and the ultimate dispo-
sition of organic chemicals  in the environ-
ment. Extensive research, focusing on  the
partitioning of neutral organic compounds,
                                          has shown that adsorption of these com-
                                          pounds generally is controlled by  hydro-
                                          phobic interactions. As a result, the affinity
                                          that a natural sorbent has for neutral or-
                                          ganic solutes can be reliably estimated, in
                                          most cases, from characterization (quanti-
                                          fication) of the hydrophobicity of chemical
                                          and sorbent. Organic carbon content has
                                          been  used almost exclusively  as a mea-
                                          sure of the hydrophobia nature of natural
                                          sedimentary material. (Organic matter or
                                          volatile solids content has also been used
                                          but not as widely.) To quantitatively char-
                                          acterize the hydrophobicity of organic
                                          compounds, researchers have used vari-
                                          ous  measurable parameters,  including
                                          octanol-water partition constants, water
                                          solubility (corrected for crystal energy), re-
                                          verse phase HPLC retention, and topologi-
                                          cal parameters of the compounds such as
                                          calculated surface area. Generally, octanol-
                                          water partition coefficients have been used
                                          more extensively, not only for estimating
                                          the partitioning of organic compounds to
                                          sedimentary  materials, but also for esti-
                                          mating bioaccumulation of organic com-
                                          pounds to aquatic organisms.
                                             Predicting the partitioning of  bnizable
                                          organic compounds is  not as  straight-
                                  forward as  for the  neutral compounds.
                                  These compounds, whether they are acids
                                  or bases, can exist as  ions  in  solution
                                  depending  upon  the pH  of the  solution
                                  according to the following equations.  For
                                  acids,
                                                                      (1)
                                  and bases,
                                          {H*}{B}/{HB*}
(2)
                                  where {H*}  is the hydrogen ion  activity,
                                  {HA} is the neutral organic acid activity (or
                                  concentration), {A~} is the organic acid an-
                                  ion activity, {B} is the neutral organic base
                                  activity, {HB*} is the protonated  organic
                                  base activity, and K. is the acid dissocia-
                                  tion constant. Among the toxicity charac-
                                  teristic compounds are ten organic acids
                                  that have pK. (-log Ka) values of relevance
                                  to environmental systems (4 < pH < 10).
                                  One compound  (pyridine) is an  organic
                                  base.
                                     The log k^ values in Table 1 were cal-
                                  culated using various equations that corre-
                                  late octano I/water partition coefficients to
                                  sorption of neutral and ionic compounds
                                  normalized to organic carbon.
Table 1. Chemical Specific Parameters—Toxicity Characteristic Contaminants, 25 "C
PREFIX CONSTITUENT
CAS NO.   calculated'
                                                                                                                Footnotes
ACRYLONITRILE
BENZENE
BIS(2-CHLOROETHYL) ETHER
CARBON DISULFIDE
CARBON TETRACHLORIDE
CHLORDANE, TECHNICAL (CIS)
CHLOROBENZENE
CHLOROFORM
2,4-D
1.4-DICHLOROBENZENE
1,2-DICHLOROBENZENE
1,2-DICHLOROETHANE
1, 1-DICHLOROETHYLENE (VINYUDENE CHLORIDE)
2,4-DINITROTOLUENE
ENDRIN
HEPTACHLOR
HEXACHLORO-1,3-BUTADIENE
HEXACHLOROBENZENE
HEXACHLOROETHANE
ISOBUTANOL (ISOBUTYL ALCOHOL)
LINDANE (HEXACHLOROCYCLOHEXANE)
M-CRESOL
METHOXYCHLOR
METHYL ETHYL KETONE
METHYLENE CHLORIDE
NITROBENZENE
O-CRESOL
P-CRESOL
PENTACHLOROPHENOL
PHENOL
107-13-1
71-43-2
111-44-4
75-154
56-23-5
57-74-9
108-90-7
67-66-3
94-75-7
106-46-7
95-50-1
107-06-2
75-35-4
121-14-2
72-20-8
76-44-8
87-68-3
118-74-1
67-72-1
78-83-1
58-89-9
108-39-4
72-43-5
78-93-3
7549-2
98-95-3
9548-7
106-44-5
87-86-5
108-95-2
4.089"
1.8V
0.8V
1.84'
2.41'
5.93-
2.39-
1.58"
0.8&
3.05*
3.08"
1.19
1.79"
1.68*
4.6V
5.21'
4.4&
5.18"
3.61'
0.44*
3.4V
1.62°
4.76"
4.03"
0.93*
1.51*
1.69s
1.62=
3.09"
1.22=
3.7E2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0.23
0
0.17
0
0
1.00E-4
0
0
0
9.61E-3
0
0
(5.5±0.5)E-2
56
0
0
0
0
1.05
0
0.69
0
1.01E-3
0
0
0
0
0
5.3E3
0
0
3.15E4
0
37.7
0
2.74E3
0
0
0
54.7
5.7E-2
0
0
0
0
0
0
0
1.74E6
0
1.2E4
0
0
0
0
0
0
0
9
h
i
\
k
1
h,m
k
h,m
h.m
h,m
k
k
h
n
o
P
h,m
k
h
1
h
q
h
r
h
h
h
h,m
h 1
                                                                                                                  (Continued)

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 Table 1. Continued

                                                                     Logl^
PREFIX CONSTITUENT
PYRIDINE
SILVEX (2,4,5-TP)
1, 1, 1,2-TETRACHLOROETHANE
1, 1,2,2-TETRACHLOROETHANE
TETRACHLOROETHYLENE (PERCHLOROETHYLENE)
2,3,4,6-TETRACHLOROPHENOL
TOLUENE
TOXAPHENE
1, 1, 1-TRICHLOROETHANE
1, 1,2-TRICHLOROETHANE
TRICHLOROETHYLENE
2,4,5-TRICHLOROPHENOL
2,4,6-TRICHLOROPHENOL
VINYL CHLORIDE
CAS NO.
110-86-1
93-72-1
630-20-6
79-34-5
127-18-4
58-90-2
108-88-3
8001-35-2
71-554
79-00-5
79-01-6
95-95-4
88-06-2
75-01-4
calculated
0.33>
1.80"
2.71'
2.07*
2.21'
2.42>
1.89-
4.31-
2.15*
1.73-
2.10"
3.12*
2.12*
1.04-
)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
y-1
0
0
1.37E-2
5.10E-3
0
0
0
7.0E-2
0.65
2.73E-S
0
0
0
<7.0E-2
(M-)
0
0
1.13E4
1.56E7
5.62
0
0
2.8E4
0
4.95E4
5.62
0
0
<3.5
Footnotes
h
h.m
k
k
k
h,m
h
1
k
k
k
h,m
h,m
s
FOOTNOTES:
• Calculated using togkx = togkm, -0.32. Hassett, J.J., J.C. Means, W.L. Banwart, S.G. Wood. 1980. Sorption Properties of Sediments and Energy
  Related Pollutants. U.S. Environmental Protection Agency, Athens, GA. EPA/600/3-80-041.
" Jafvert, assumes partitioning of ion to be a factor of 2 less than neutral species (35). Jafvert, C. T. 1990. Environ. Tox. Chem. In Press.
' Calculated from KK = 1.05 KJ*">
d Calculated from K^= 1.05KJ*"> (1.0/(1.0+KJ[H>])), where [H*]= 1.0X WM(25). Schellenberg, K., C. Leuenberger, R.P. Schwarzenbach. 1984.
  Environ. Sd. Tech. 18:652-657.
• Calculated from log Kx = tog KM -0.32 (34). Hassett, J.J., J.C. Means, W.L Banwart, S.G. Wood. 1980. Sorption Properties of Sediments and Energy
  Related Pollutants. U.S. Environmental Protection Agency, Athens, GA. EPA/600/3-80-041.
1  kK values tor bnizable organic compounds (as denoted by b,c,d,e in the Log kx column) were calculated at pH 7.
' Ellington, J.J., F.E. Standl, and W.D. Payne. 1986. Measurement of Hydrolysis Rate Constants for Evaluation of Hazardous Waste Land Disposal.
  Volume I. U.S. Environmental Protection Agency, Athens, GA. EPA/600/3-86/043.
" Roberts, J.D. andM.C. Caserio. 1965. Basic Principles of Organic Chemistry, W.A. Benjam Inc., New York.
1  Ellington, J.J., F.E. Standl, W.D. Payne, and C.D. Trusty. 1988. Measurement of Hydrolysis Rate Constants for Evaluation of Hazardous Waste Land
  Disposal. Volume III. Data on 70 Chemicals. U.S. Environmental Protection Agency, Athens, GA. EPA/600/3-88/028.
I  Elliot, S. 1990. Environ. Sci.  Technol. 24:264-267.
"Jeffers, P.M., L Ward, L Woytowitch, andN.L. Wolfe.  1989. Environ. Sci. Technol. 23, P 965-969.
'  Ellington, J.J., F.E. Standl, W.D. Payne, andC. Trusty. 1987. Measurement of Hydrolysis Rate Constants for Evaluation of Hazardous Waste Land
  Disposal. Volume II. Data on 54 Chemicals. U.S. Environmental Protection Agency, Athens, GA. EPA/600/3-87/019.
m Jeffers, P.M. Private communication. Peter M. Jeffers,  Department of Chemistry, State University of New York, Cortiand, NY.
" Ellington, J.J., F.E. Standl, W.D. Payne, and C.D. Trusty. 1988. Interim Protocols tor Measuring Hydrolysis Rate Constants in Aqueous Solutions. U.S.
  Environmental Protection Agency, Athens, GA. EPA/600/3-88/014.
' Chapman, R.A. and CM Cole. 1982. J. Environ. Sd. Health B17(5):487-504.
"Jeffers, P.M. andN.L Wolfe. 1989. Neutral and Alkaline Rate Constants for Hydrolysis of Chlorinated Alkanes and Alkenes. Presentedat Padfichem
  '89, December 17-22, 1989,  Honolulu, HI.
" Wolfe, W.L, R.G. Zepp, D.F. Paris, G.L Baughman, andR.C. Hollis. 1977. Environ. Sd. Technol. 11(12):1077-1081.
'  Fells, I. andE.A.  Moelwyn-Hughes. 1958. J. Chem. Soc., Part 2, No. 268:1326-1333.
•  Hill, J., H.P. KolKg, D.F. Paris, N.L Wolfe, R. G. Zepp. 1976. Dynamic Behavior of Vinyl Chloride in Aquatic Ecosystems. U.S. Environmental Protection
 Agency, Athens,  GA. EPA/600/3-76/001.
                                                                                   •ft-U.S. GOVERNMENT PRINTING OFFICE: 1991/548-028/20176

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   7770 EPA authors, J. Jackson Ellington (also the EPA Project Officer, see below),
    Chad T. Jafvert, Heinz P. Kollig, Eric J. Weber, and N. Lee Wolfe are with the
    Environmental Research Laboratory, Athens, GA 30613.
   The complete report, entitled "Chemical-Specific Parameters for Toxicfty Charac-
    teristic Contaminants," (Order No. PB91-148 361/AS; Cost $15.00, subject to
    change) will be available only from:
         National Technical Information Service
         5285 Port Royal Road
         Springfield, VA 22161
         Telephone: 703-487-4650
   The EPA Project Officer can be contacted at:
         Environmental Research Laboratory
         U.S. Environmental Protection Agency
         Athens, GA 30613
United States
Environmental Protection
Agency
Center for Environmental Resea
Information
Cincinnati, OH 45268
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