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)
-------
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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