United States
Environmental Protection
Agency
Environmental
Research Laboratory
Athens, GA 30605-2720
Research and Development
EPA/600/SR-93/132 September 1993
EPA Project Summary
Environmental Fate
Constants for Organic Chemicals
Under Consideration for EPA's
Hazardous Waste Identification
Projects
Heinz P. Kollig
Under Section 301 of the Resource
Conservation and Recovery Act
(RCRA), EPA's Office of Solid Waste
(OSW) is in the process of identifying
chemicals to be considered in projects
called the hazardous waste identifica-
tion projects. At this time, there are
some 200 chemical constituents identi-
fied in these projects. This publication
addresses environmental fate constants
and chemical hydrolysis pathways for
the 189 organic chemicals already iden-
tified. Chemical hydrolysis rate con-
stants for parent compounds and prod-
ucts including structural presentation
of the pathways are presented. Redox
rate constants are given for selected
compounds. Sorption coefficients are
presented for parents and products in
terms of the octanol/water partition co-
efficient and the organic-carbon-normal-
ized sediment/water partition coeffi-
cient. The ionization constant is given
when this process affects sorption in
the environmental pH range.
This Project Summary was developed
by EPA's Environmental Research
Laboratory, Athens, GA, to announce
key findings of the research project
that is fully documented in a separate
report (see Project Report ordering in-
formation 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 chemi-
cals under various environmental reaction
conditions. Whether mathematical models
or other assessment techniques are em-
ployed, knowledge of equilibrium and ki-
netic constants (fate constants) is required
to predict the transport and transformation
of these chemicals.
Under Section 301 of RCRA, EPA's
OSW has identified wastes that may pose
a substantial 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 environ-
ment of selected chemicals.
EPA continues to believe that the
Agency must assure continuity of the haz-
ardous waste program while developing
appropriate revisions. While fully preserv-
ing existing hazardous waste identifica-
tion rules, EPA is considering alternatives
to take an initial step towards defining
wastes that do not merit regulation under
Subtitle C and that can and will be safely
managed under other regulatory regimes.
In the course of developing appropriate
revisions, OSW is in the process of identi-
fying chemicals to be considered in
projects called the'hazardous waste iden-
tification projects. At this time, there are
some 200 chemical constituents identi-
fied. The 189 proposed organic chemicals
are addressed in this report.
Printed on Recycled Paper
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Synopsis of Report
This report is composed of two parts.
Part I Includes text and data on chemical
hydrolysis, sorption, and redox reactions.
In the hydrolysis section, hydrolysis kinet-
ics are elucidated for the chemical classes
of hatogenated aliphatics, organophospho-
rus esters, carboxylic acid esters, amides,
carfaamates, and n'rtriles. In the sorption
section, the sorption of neutral and ioniz-
able organic compounds is addressed in-
cluding computational techniques. In the
redox section, the kinetics of the unex-
plored area of heterogeneous redox reac-
tions is elucidated. Part I concludes with a
table listing hydrolysis products (interme-
diate and final) including rate constants
for parents and intermediates, and sorp-
tion data for parents and for intermediate
and final products, and a table listing com-
puted redox rate constants at different lev-
els of organic carbon for selected haloge-
nated aliphatics and nitroaromatics. Part
II includes text and structural pathways of
chemical hydrolysis for all organics that
undergo this process. Non-hydrolyzing or-
ganics are identified and their structures
are given.
As an illustration of the data provided,
two pages from the complete report are
reproduced in this summary. The example
organic compound is methyl parathion.
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140
Fate Constants for Hazardous Waste Identification
141. Methyl parathion
Hydrolysis of methyl parathion may occur through either reaction with H20 (neutral hy-
drolysis) or reaction with HO (base-mediated hydrolysis). Nucleophilic substitution by tip
occurs in sequence at the two methoxy carbons to yield 0-methyl-O-(p-nitrophenyl)-
phosphorothioic acid (diester) and O-fc-nitrophenyl)phosphorothioic acid (monoester),
respectively. Loss of the second methyl group itrom the disubstituted ester would be at a
rate approximately a factor of 10 less than the loss of the methyl group from the triester.
Hydrolysis of the monosubstituted ester [O-(p-nitrophenyl)phosphorothioic acid] would
proceed through cleavage of the P-O bond at a rate of approximately one-half the rate of the
parent triester. Hydroxide-ion-mediated hydrolysis of methyl parathion proceeds through
initial attack of the hydroxide ion on the phosphorus atom with displacement of the p-
nitrophenylate ion. Loss of the two methyl groups from the 0,O-dimethylphosphorothioic
acid will proceed as described above. The phosphorothioic acid generated in each hydrolytic
pathway will eventually degrade to phosphoric acid and hydrogen sulfide.
H3C
H3C
Methyl parathion
HsC-0 ,
O-Methyl-O-(p-nitrophenyl)phosphorothioic acid O,C)-Dimethylphosphorothioic acid p-Nitrophenol
CH3OH
Methanol
H3C
-OH
CH3OH
O-Methylphosphorothioic acid Methanol
O-(p-Nitropnenyl)phospnorotnioic acid
I + CHgOH
{ Methanol
HO,
+ HO/ V-NO2
;P-OH
Phosphorothioic acid p-Nitrophenol
+ CH3OH
Phosphorothioic acid Methanol
H2S
DH + H2S
Phosphoric acid
Phosphoric acid , ,
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40 Fate Constants for Hazardous Waste Identification
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Heinz P. Kollig, (also the EPA Project Officer.see below) is with the Environ-
mental Research Laboratory, Athens, GA 30605-2720.
The complete report, entitled "Environmental Fate Constants for Organic
Chemicals Under Consideration for EPA's Hazardous Waste Identification
Projects," (Order No. PB93-221646AS; Cost: $27.00; 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 Off leer can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
Athens, GA 30605-2720
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use $300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/6QO/SR-93/132
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