United States
Environmental Protection
Agency
Environmental Research
Laboratory
Athens, GA 30613-7799
Research and Development
EPA/600/S3-91/016 June 1991
EPA Project Summary
Microbial Transformation Rate
Constants of Structurally Diverse
Man-made Chemicals
William C. Steen
To assist In estimating mlcrobially
mediated transformation rates of man-
made chemicals from their chemical
structures, all second order rate con-
stants that have been measured under
conditions that make the values com-
parable have been extracted from the
literature and combined with rate con-
stants not reported before to compile a
comprehensive list of second order rate
constants for chemicals of diverse
structures. Chemicals for which con-
stants are presented include seven
chlorinated carboxyllc acid esters of
2,4-dlchlorophenoxyacetlc acid (2,4-D),
phenol and seven substituted phenols,
three phthalate esters, three anilines,
seven amides, and seven acetanilldes.
The 35 constants were measured in the
laboratory by a protocol that measures
disappearance of the chemical sub-
strate as & function of time In the
presence of suspended natural popu-
lations from unpolluted aquatic sys-
tems. Second order rate constants, k2
(L org/1 hr/1), range from 4.2 x 10-* for
the hexyl acid ester of 2,4,-D to 4.2 x
10-" for the dl-ethylhexyl phthalate es-
ter.
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 of the same title (see Project
Report ordering Information at back).
Overview
For many man-made chemicals, a ma-
jor mechanism determining persistence in
the ambient environment is microbially
mediated transformation. As the U.S. En-
vironmental Protection Agency reviews
chemicals to determine their potential im-
pact on the environment, information is
required concerning the rates at which
new and existing compounds will undergo
microbial transformation under environ-
mental conditions. Relevant information for
individual chemicals is sparse in the litera-
ture.
In the absence of measured microbial
transformation rate constants, reviewers
must estimate the rate on the basis of
chemical structure. To assist in predicting
microbial transformation from chemical
structure, this report lists second-order
microbial transformation rate constants,
measured in the laboratory using the same
protocol, for 35 chemicals of diverse
chemical structure (see Table 1). Included
in the data are rates for seven para-sub-
stituted acetanilides not reported previ-
ously.
Printed on Recycled Paper
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Tabto 1. Second-order Microbial Transformation Rate Constants for 35 Organic Chemicals
Chemical Class CAS No. k,(L org. -' hr.-')
Csrboxylic Add Esters of2,4-D
Butyl
Butoxy ethyl
Ethyl
Hexyf
Methyl
Octyl
Propyl
Phenols
Phenol
p-acetyl
p-bromo
p-chtoro
p-cyano
p-n'tro
p-methoxy
p-methyl
Phthalate ester
di-butyl
dt-othylhexyl
dloctyl
Anilines
AniUno
3-chhro
3-nitro
Amides
2-acetamidofluorenB
BenzanllidB
Monalida
Niclosamida
PronamidB
Propachtor
Propanil
Acetanilidas
Acetanilide
p-bromo
p-chtoro
p-cyano
p-msthoxy
p-methyl
p-nitro
(94-80-4)
(1929-73-3)
(533-23-3)
(1917-95-9)
(1928-38-7)
(1928-44-5)
(108-95-2)
(99-93-4)
(106-41-2)
(106-48-9)
(767-00-0)
(100-02-7)
(150-76-5)
(106-44-5)
. (84-74-2)
(117-81-7)
(117-84-0)
(62-53-3)
(108-42-9)
(99-09-2)
(53-96-3)
(93-98-1)
(7287-36-7)
(50-65-7)
(23950-58-5)
(1918-16-7)
(709-98-8)
(103-84-4)
(103-88-8)
(539-03-7)
(35704-19-9)
(51-66-1)
(103-89-9)
(104-04-1)
(4.1 ± 1.2) X 10°
(5.4±2.7)X1O">
(5.2±1.6)X1O'°
(4.2 ± 3.3) X 10*
(5.8 ± 0.9) X 1V°
(3.2 ± 1.1) X 10*
(2.9 ± 1.2) X 10'
(3.3±1.2)X10<°
(2.0±1.0)X10'°
(9.1±1.0)X1O"
(7.1±1.6)X1O"
(4.2±1.7)X1OK
(3.8 ± 1.4) X 10"
(2.2 ± 1.1) X 10"
(2.7± 1.3) X 10-"
(3.1 ± 0.8) X 10"
(4.2 ± 0.7) X W*
(3.7± 0.6) X 1O<3
(1.1±0.8)X1&"
(2.2 ± 1.7)X1&<*
(4.6±0.1)Xma
(4.8±2.8)Xm<*
(2.4±0.7)X1V*
(6.0±2.3)XW3
(2.0 ± 0.8) X 1&u
(5.0 ± 2.3) X 1&"
(1.1±0.9)X10»
(5.0±2.7)X1Cr">
(1.48±1.02)Xia"
(3.85 ± 2.27) X m"
(1.1 1± 0.65) X 10-"
(1.45±1.19)X10-13
(8.51 ± 3.97) X 10-'3
(1.70 ± 0.57) X 10-"
(2.20 ± 0.68) X10-1*
•frll.S. GOVERNMENT PRINTING OFFICE: 1991 - 948-028/40004
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The EPA author, William C. Stson (also the EPA Project Officer, see below), is with
Environmental Research Laboratory, Athens, GA, 30613-7799.
The complete report, entitled ' Mhrobial Transformation Rate Constants of Struc-
turally Diverse Man-made Chemicals," (Order No. PB91-181 958/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 Off her can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
Athens, GA 30613-7799
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/800/S3-91/016
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