UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, DC 20460

OFFICE OF PREVENTION, PESTICIDES, AND TOXIC SUBSTANCES

 

						

July 6, 2006

MEMORANDUM

SUBJECT:	Environmental Fate Assessment of Alkylbenzene Sulfonates for
the Registration Eligibility Document (RED).

TO:	Heather Garvie, Chemical Review Manager, Reregistration Team 36

	Regulatory Management Branch II

Antimicrobials Division (7510C)

		

		And

Deborah Smegal, Risk Assessor

Reregistration Branch I

Health Effects Division (7509C)

FROM:	Talia Milano, Chemist, Team II

	Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510C)

THRU:	Norm Cook, Branch Chief

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510C)

DP Barcode:  323968 

Case No.: 4006

Chemical Names (CAS #)1:  

              Sodium dodecylbenzene sulfonate (#25155-30-0),
Benzenesulfonic acid, C10-16-alkyl

              derivatives (#68584-22-5), and Dodecylbenzene sulfonic
acid (#27176-87-0)

1: The CAS #  listed reflect the current numbering system. However,
dodecylbenzene sulfonic acid is not a pure chemical, and is considered
part of the mixture of benzenesulfonic acid.  A discussion of this
discrepancy can be found in the text and in the Preliminary Risk
Assessment.

ENVIRONMENTAL FATE ASSESSMENT OF 

ALKYYLBENZENE SULFONATES

CASE 4006

PC CODE: 190116

7/6/06

 

Antimicrobials Division

Office of Pesticide Programs

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue, NW

Washington, DC 20460

Table of Contents

EXECUTIVE SUMMARY
………………………...…………………………………..
………..…4

.

1.0
INTRODUCTION……………………...……………………………
………………....……….5

	1.1
Purpose………………………...……………………………
………………....………....5

	1.2 Chemical
Identification…………………………...……………………
……..………….5

2.0 USE
INFORMATION……………………...……………………………
…………..……..…..6

	2.1 Formulation Type and Percent Active
Ingredient…..........................................................6

	2.2 Summary of Use Patterns and
Formulations………………………....…....….…...……..6

3.0 MODEL RESULTS. . . . . . . . . . .
………………………………………………….…………..
7

	3.1 EPI Suite Output for sodium dodecylbenzene
sulfonate…………...……………………7

	3.2 EPI Suite Output for
DDBSA…………………………...……………………………
….8

4.0 ADDITIONAL DATA FROM LITERATURE
SEARCH........……………......…….…..….9

	4.1 Sodium dodecylbenzene
sulfonate………………………...……...…………....……
….10

	4.2
DDBSA………………………...………………………………
……………..…….......10

5.0
CONCLUSION……………………………..………………………
……………………….....11

6.0
REFERENCES………………………………..……………………
………………….....……12EXECUTIVE SUMMARY

This document is the Environmental Fate Assessment Chapter of the
Reregistration Eligibility Decision Document (RED) for the alkylbenzene
sulfonates.  The currently listed active ingredients that are included
under this decision are sodium dodecylbenzene sulfonate (CAS #
25155-30-0), dodecylbenzene sulfonic acid (CAS # 27176-87-0), and
benzenesulfonic acid, C10-C16 alkyl derivatives (CAS # 68584-22-5).  To
date, dodecylbenzene sulfonic acid has been listed separately from
benzenesulfonic acid, C10-C16 alkyl derivatives, and identified by the
CAS #27176-87-0 on numerous labels and in different databases.

The environmental fate properties of dodecylbenzene sulfonic acid are
assumed to be represented by the conclusions made pertaining to
benzenesulfonic acid, C10-C16 alkyl derivatives.  This is because
dodecylbenzene sulfonic acid is not considered to be a pure compound,
and is actually included in the mixture of benzenesulfonic acid, C10-16
alkyl derivatives.  These two compounds will be addressed as a group,
DDBSA, throughout the document.  This issue of dodecylbenzene sulfonic
acid being a subsidiary of benzenesulfonic acid, C10-16 alkyl
derivatives is discussed in more detail in the Preliminary Risk
Assessment.  

The conclusions presented in this environmental fate chapter are based
on the United States Environmental Protection Agency’s (USEPA’s)
Estimation Programs Interface (EPI) Suite and a literature search.  EPI
Suite provides estimations of physical/chemical properties as well as
environmental fate properties.

 

Based on the output of the model, sodium dodecylbenzene sulfonate is
highly unlikely to bioaccumulate in the environment or aquatic organisms
(i.e. fish) because the low value for the log Kow (1.96).  This also
supports that the chemical is soluble in water such that it will exhibit
mobility through the soil.  In addition, the low log Koc (4.22) further
supports the expected soil mobility.  The model-calculated linear and
non-linear biodegradation probabilities suggest that the linear carbon
chain will biodegrade rapidly, whereas the benzene ring is not expected
to biodegrade as rapidly.  The extremely low vapor pressure along with
the short half life of approximately 7.9 hours indicates that if this
chemical is present in the soil, it is not likely to be volatile and is
expected to degrade rapidly.  

Based on the output of the model, DDBSA is expected to behave very
similarly as what is projected for sodium dodecylbenzene sulfonate. 
Based on the low Kow value (3.80), DDBSA is highly unlikely to
bioaccumulate in the environment or aquatic organisms (i.e. fish).  The
chemical is also expected to be soluble in water such that it will
exhibit mobility through the soil.  In addition, the log Koc (3.69) is
low, and this further supports the expected soil mobility.  The
model-calculated linear and non-linear biodegradation probabilities
suggest that the chemical will most likely biodegrade rapidly.  The
extremely low vapor pressure along with the short half life of
approximately 9.48 hours indicates that this chemical is not likely to
be volatile and is likely to degrade rapidly in soils.

The output parameters from the EPI Suite model support that potential
impacts for both of these chemicals are expected to be very short-lived.
 This is because they are not likely to persist in water or microbial
soils and sediments.  As a result, the environmental fate of
alkylbenzene sulfonates is not likely to be of a concern.

1.0	 INTRODUCTION tc \l1 "1.0	 INTRODUCTION 

		1.1	Purpose  tc \l2 "1.1	Purpose  

	

	In this document, the Agency presents the results of its review of the
potential environmental fate of the alkylbenzene sulfonates, and this
information is for use in EPA's development of the Alkylbenzene
Sulfonates Reregistration Eligibility Decision Document (RED).  

	The types of studies indicated by the, “Pesticide Assessment
Guidelines, Subdivision N,” as being useful for performing
environmental fate assessments are degradation studies, metabolism
studies, mobility studies, dissipation studies, and accumulation
studies. After a search through the USEPA’s archives, there are a
handful of studies that discuss the environmental behavior of the
chemicals addressed in this chapter, however there are no current data
evaluation reports (DER’s) for the corresponding studies.  This
absence of documentation is supported by the following memorandum in
USEPA’s files:

Memo dated March 2, 1993 (DP Barcodes D185513 and D185394), with the
subject: “Phase IV – List D Chemicals; Registration Case #4006,”
indicates that, “environmental fate assessments can be generated from
data available in-house and from information published in the open
chemical literature.”  In addition to this statement, the memo
provides a list of the different criteria that need to be met to fulfill
the environmental fate requirements.  On the list, it is indicated that
each criteria has been either satisfied or waived for both sodium
dodecylbenzene sulfonate (CAS # 25155-30-0) and dodecylbenzene sulfonic
acid (CAS # 68584-22-5).

	In addition to the supporting memorandum, the EPI Suite model was run
to collect the different environmental properties of the chemicals
addressed in this case.  These values are provided in Section 3.0,
“Model Results.”  The Agency conducted a literature search to
further support the output parameters that were provided by the EPI
Suite model.  The results of the literature search are presented in
Section 4.0, “Additional Data From Literature Search.”

	Minimal or no environmental exposure is expected to occur from the
majority of linear alkylbenzene sulfonate uses and it is unlikely that
any appreciable exposure to terrestrial or aquatic organisms would occur
from limited commercial down-the-drain use because of the very small
number of pounds sold for these uses (CBI data).  It is conclusive from
the chemical properties of the alkylbenzene sulfonates and the published
literature that there are most likely no environmental impacts to be
concerned with at this time. 

		1.2 Chemical Identification:

		 

	Three chemicals are considered in this document: sodium dodecylbenzene
sulfonate, benzene sulfonic acid, C10-16 alkyl derivatives, and
dodecylbenzene sulfonic acid.  It is important to reiterate that even
though benzene sulfonic acid, C10-16-alkyl derivatives and
dodecylbenzene sulfonic acid are listed as separate active ingredients
when denoted on labels, dodecylbenzene sulfonic acid is assumed to
exhibit the same environmental effects as the benzene sulfonic acid,
C10-16-alkyl derivatives.  Additionally, these two chemicals will be
jointly referred to as DDBSA throughout the document and conclusions
will be made based on the properties affiliated with benzene sulfonic
acid, C10-16-alkyl derivatives. Table 1 shows chemical information that
was used for sodium dodecylbenzene sulfonate and DDBSA.  This data in
Table 1 was extracted from the Product Chemistry Science Chapter that
has been developed for the alkylbenzene sulfonate RED.

	

Table 1.  Chemical Identification Information Alkylbenzene Sulfonatesa



	Sodium Dodecylbenzene Sulfonate	Benzene Sulfonic Acid, C10-16-alkyl
derivatives (DDBSA)



CAS Number	25155-30-0	68584-22-5



Molecular Formula	C18H29O3NaS	C18H30O3S

a:  Refer to the product chemistry chapter for a full list of the
different chemical and physical properties of each of these compounds.  
                                                                       

2.0	 USE INFORMATION tc \l1 "2.0	 USE INFORMATION 

		2.1	 Formulation Types and Percent Active Ingredient tc \l2 "2.1	
Formulation Types and Percent Active Ingredient 

		The products containing alkylbenzene sulfonates as the active
ingredients (a.i.) are formulated as soluble concentrates, flowable
concentrates, ready-to-use solutions, and water soluble packaging. 
Concentrations of alkylbenzene sulfonates in these products range from
0.036% to 25.6%.  In the past registrations, there was a use for acid
mine treatments that involved sodium dodecylbenzene sulfonate.  The
labels that have these uses have been voluntarily cancelled by the
registrant.  As a result, there are no terrestrial uses of this chemical
to be concerned with for this RED.

		2.2	 Summary of Use Patterns and Formulations tc \l2 "2.2	 Summary of
Use Pattern and Formulations 

The Agency determines potential exposures to the product by identifying
exposure scenarios from the various application methods that are
plausible, given the label uses. Based on a review of registered product
labels, the use categories for alkylbenzene sulfonates include
agricultural premises and equipment, food handling/storage establishment
premises and equipment, and commercial /institutional and industrial
premises and equipment (Use Site Categories I, II, and III
respectively).  Examples of registered uses for alkylbenzene sulfonates
include, but are not limited to: application to indoor hard surfaces
(e.g. urinals, shower stalls, toilet bowls, etc.), food dispensing
equipment (e.g. pre-mix and post-mix vending machines), food contact
surfaces (glasses, dishes, silverware, countertops, etc.), agricultural
tools, and fruits and vegetables (post-harvest).  The percentage of
alkylbenzene sulfonates in various products can range from 0.036% to
25.6%.  Products containing alkylbenzene sulfonates are formulated as
soluble concentrates, flowable concentrates, ready-to-use solutions, or
water soluble packaging.   All of the scenarios are highly unlikely to
produce environmental fate concerns.

MODEL RESULTS

	EPI Suite contains ten models, not all of which were executed for this
chapter.  EPIWIN, Estimations Programs Interface for Windows, is an
interface program that transfers a single SMILES notation to eleven
separate structure estimation programs.  These programs are useful
because they provide chemical properties so that different estimations
can be made about the behavior and properties of the particular chemical
being discussed.  The programs that provided output applicable to this
chapter are: 

AOPWIN: This estimates the rate constant for the atmospheric gas-phase
reaction between photochemically reduced hydroxyl radicals and organic
chemicals.  It then uses the calculated rates to estimate the half-lives
for organic compounds based upon average atmospheric concentrations of
hydroxyl radicals and ozone.

BIOWIN: Estimates the probability for the rapid aerobic biodegradation
of an organic chemical in the presence of mixed populations of
environmental microorganisms.  Estimates are based upon fragment
constants that were developed using multiple linear and non-linear
regression analyses.  

HENRYWIN: Estimates Henry’s law constant. 

KOWWIN: Estimates the octanol-water partition coefficient

MPBPWIN: estimates the melting point, boiling point, and vapor pressure

PCKOCWIN: Estimates the soil sorption coefficient, KOC of organic
compounds.  The output can be defined as the ratio of the amount of
chemical adsorbed per unit weight of organic carbon (oc) in the soil or
sediment to the concentration of the chemical in solution at
equilibrium.  The coefficient provides an indication of the extent to
which a chemical partitions between solid and solution phases in soil,
or between water and sediment in aquatic ecosystems.  

WSKOWWIN: Estimates the water solubility from the log octanol-water
partition coefficient.

The following sections, 3.1 and 3.2 respectively, provide the chemical
specific conclusions that are based on model output.  

	3.1 EPI Suite Output for sodium dodecylbenzene sulfonate (CAS #
25155-30-0)

log Kow: 1.96

Koc: 1.683 E +004 (log Koc: 4.22)

MP: 287.6OC

BP: 660 OC

VP: 6.02 E-015 mm Hg

Water solubility: 800 mg/L

Henry’s Law Constant: 6.02 E-017 atm-m3/mol

Linear biodegradation probability: 0.5314

Non-linear biodegradation probability: 0.4415

Half life: 7.9 hrs (in the air or atmosphere)

	Based on the output of the model, sodium dodecylbenzene sulfonate is
highly unlikely to bioaccumulate in the environment or aquatic organisms
(i.e. fish) because of the low Kow value.  This suggests that the
chemical is soluble in water such that it will exhibit mobility through
the soil.  “In general, the higher its octanol-water partition
coefficient Kow, the more likely a chemical is to be bound to organic
matter in soils and sediments…Thus, it is chemicals with log Kow
values in the 4-7 range that bioconcentrate to the greatest degree”
(Barid 303).  In addition, the log Koc is low, and this further supports
that dodecylbenzene sulfonate will most likely exhibit soil mobility. 
This is because it is not expected to immediately bind to the soil
sediments.

	The model-calculated linear and non-linear biodegradation probabilities
provide information about the rate of the degradation of the
constituents of sodium dodecylbenzene sulfonate in the environment.  For
numerical comparisons, the BIOWIN model indicates that numbers greater
than or equal to 0.5 indicate rapid biodegradation and numbers less than
0.5 do NOT biodegrade quickly.  For the sodium dodecylbenzene sulfonate,
it is expected that the linear carbon chain will biodegrade rapidly,
whereas the benzene ring is not expected to biodegrade as rapidly.  The
same model also provides an estimation of the behavior of the chemical
in the aquatic environment as well as ultimate biodegradation
(mineralization).  It is estimated that the chemical will biodegrade
linearly within days in the aquatic environment, whereas ultimate
biodegradation is estimated to take place over the course of weeks. 

	The extremely low vapor pressure along with the short half life of
approximately 8 hours indicates that this chemical is not likely to be
volatile, and is likely to degrade rapidly by reaction with
photochemically produced hydroxyl radicals in air.  The short half-life
supports that any potential impacts of the chemical may be very
short-lived because the chemical is not likely to persist in water or
microbial soils and sediments.

	As an aside, insignificant exposure to sodium dodecylbenzene sulfonate,
also commonly refeered to as LAS, in the environment is expected for the
following reasons: 1.) total LAS usage for these industrial applications
is very minor - a very small percentage of the total pounds used in
antimicrobials (CBI data); and commercial only use precludes broad
environmental exposures that might occur with residential use, 2.)  LAS
breakdown and degradation in the environment is very rapid, 3.) LAS is
significantly reduced by sewage treatment.   Industrial water treatment
requires a NPDES permit in order to discharge effluents.    

	3.2  EPI Suite Output for DDBSA  (CAS # 68584-22-5)

log Kow: 3.80

Koc: 4.95 E+003 (log Koc: 3.69)

MP: 167.7OC

BP: 437OC

VP: 5.1 E-010 mm Hg

Water solubility: 400g/L (@250C)

Henry’s Law Constant: 2.8 E-011 atm-m3/mol

Linear biodegradation probability: 0.5448

Non-linear biodegradation probability: 0.5407

Half life: 9.48 hrs (in the air or atmosphere)

	Based on the output of the model, DDBSA is highly unlikely to
bioaccumulate in the environment or aquatic organisms (i.e. fish)
because of the low log Kow value.  This value suggests that the chemical
is soluble in water such that it will exhibit mobility through the soil.
 Again, the Kow value is low such that the chemical will be highly
unlikely to bioconcentrate and is in other words, mobile (Barid 303). 
In addition, the log Koc is low, and this further supports that
dodecylbenzene sulfonate will most likely exhibit soil mobility.  This
is because it is not expected to immediately bind to the soil sediments.

	The model-calculated linear and non-linear biodegradation probabilities
provide information about the rate of the degradation of the
constituents DDBSA in the environment.  For numerical comparisons, the
BIOWIN model indicates that numbers greater than or equal to 0.5
indicate rapid biodegradation and numbers less than 0.5 do NOT
biodegrade quickly.  For the DDBSA, it is expected that overall molecule
will most likely biodegrade rapidly.  The same model also provides an
estimation of the behavior of the chemical in the aquatic environment as
well as ultimate biodegradation (mineralization).  It is estimated that
the chemical will behave similarly to LAS and biodegrade linearly within
days in the aquatic environment, and ultimate biodegradation is
estimated to take place over the course of weeks. 

	The extremely low vapor pressure along with the short half life of
approximately 9 hours indicates that this chemical is not likely to be
volatile and is likely to degrade rapidly by reaction with
photochemically produced hydroxyl radicals in air.  In addition, the
short half-life supports that any potential impacts may be very
short-lived because the chemical is not likely to persist in water and
microbial soils and sediments.

 4.0 ADDITIONAL DATA FROM LITERATURE SERACH

	There are minimal studies in house that provide environmental fate data
for the two CAS numbers affiliated with this RED.  A literature search
was conducted for different published articles that could be used as
resources for providing information on the chemical behavior of the
alkylbenzene sulfonates in the environment.  There was a sufficient
amount of information available for LAS, but not on DDBSA.  Section 4.1
provides a summary of the different published literature that discusses
the environmental behavior of LAS.  This literature search serves to
supplement the conclusions derived from the EPI Suite model output
(Section 3.0).  Section 4.2 discusses the conclusions for DDBSA.  The
excerpts also serve as a foundation for the conclusion that the
environmental fate of alkylbenzene sulfonates is not likely to be of a
concern.  

	4.1 Sodium dodecylbenzene sulfonate (CAS # 25155-30-0)

	Several excerpts are included for a discussion of this chemical to
provide a well rounded understanding of its behavior in the environment.
The location of the full text of where these excerpts were obtained from
is fully referenced in the bibliography.

“LAS biodegrades easily and loses its tensioactive properties quickly,
as many works of literature testify” (Cavalli 1993).

“Throughout their passage into the environment, LAS are removed by a
combination of adsorption and primary and ultimate bio-degradation.  LAS
are adsorbed onto colloidal surfaces and onto suspended particles…they
biodegrade in surface water (half-life 1-2 days), aerobic sediments (1-3
days), and marine and estuarine systems (5-10 days) (WHO 1996).

“For anionic surfactants in general, the most important compartments
[where LAS can be found in the environment] are sewage water treatment
plants, surface waters, sediment- and sludge-amended soils, and
estuarine and marine environments.  Both biodegradation (primary and
ultimate) and adsorption occur, resulting in decreased environmental
concentrations and bioavailability.  Reduction in chain length and loss
of the parent structure both result in compounds that are less toxic
than the parent compound.  It is important that these considerations be
taken into account when the results of laboratory tests are compared
with potential effects on the environment” (WHO 1996).

“The sorption of LAS to soil is a combination of several mechanisms
and sorption to both the organic and inorganic fraction of the soil has
been demonstrated.  The linear alkyl group of LAS is hydrophobic and
sorbs to the non-polar fractions of the soil, such as the organic
matter.  However, the sulfonate group of LAS is negatively charged and
hydrophilic and therefore interacts with positively charged soil
components or polar groups, such as hydroxyl-groups, minerals, or
oxides” (Jacobsen 2004).

“Environmental degradation of LAS homologs in aquatic systems is
rapid; the measured half-life in river waters is <2 d[ays].  Degradation
processes rapidly reduce chain lengths of LAS in the environment to
averages lower than C12,” and in addition to this research finding,
“[t]oxicity generally decreases with decreasing chain length”
(Fairchild 1993).  This supports that this chemical has an extremely
short-lived presence in the environment, and its degradates are less
toxic than the parent compound. 

In a published review by Kuhnt (1993), a flow chart is provided to
depict the behavior of surfactant in soils.  It is conclusive from the
flow chart that surfactants that exhibit either low or no adsorption can
exhibit enhanced mobility and degradability, which result in low
persistence in the environment.

	4.2 DDBSA  (CAS # 68584-22-5)

	There is a deficiency in the availability of literature on DDBSA. The
major difference between LAS and DDBSA are the ions on the sulfonate
groups which are sodium versus hydrogen respectively.  It is important
to also acknowledge that, “[t]he commercial mixture of LAS is composed
of a range of homologs with alkyl chain lengths ranging from 10 to 15
carbon units and isomers that vary in phenol position” (Fairchild
1763).  This supports that LAS is very similar to DDBSA in terms of the
length of the carbon chain, and the empirical formulas provided in Table
1, Chemical Identification Information for Alkylbenzene Sulfonates
further support this.  

5.0 CONCLUSION

As a result of the structural observations and comparisons between LAS
and DDBSA along with the similar properties provided by EPI Suite, the
literature data that is available for LAS is assumed to be
representative of DDBSA.   In conclusion, the potential effects of both
LAS and DDBSA in the environment are not likely to be of a concern.  

6.0 REFERENCES

Barid, Colin.  Environmental Chemistry, 2nd Edition.  W.H. Freeman and
Company: New York, 2003.

Cavalli, L., et. al. (1993). “LAS Removal and Biodegradation in a
Wastewater Treatment Plant.” Environmental Toxicology and Chemistry.
Vol. 12. pp 1777-1788. 

Fairchild, James F, et. al. (1993).  “Evaluation of a
Laboratory-Generated OEC For Linear Alkylbenzene Sulfonate in Outdoor
Experimental Streams.”  Environmental Toxicology and Chemistry. Vol.
12. pp 1763-1776.

“International Programme on Chemical Safety, Environmental Health
Criteria 169, Linear Alkylbenzene Sulfonates and Related Compounds.”
World Health Organization. Geneva, 1996   HYPERLINK
"http://inchem.org/documents/ehc/ehc/ehc169.htm" 
http://inchem.org/documents/ehc/ehc/ehc169.htm . 

Jacobsen, Anne Marie, Gerda Krog Mortensen, and Hans Christian Bruun
Hansen. (2004). “Degradation and Mobility of Linear Alkylbenzene
Sulfonate and Nonylphenol in Sludge-Amended Soil.” Journal of
Environmental Quality. Vol 33. pp. 232-240.

Kuhnt, Gerald. (1993).  “Behavior and Fate of Surfactants in Soil.”
Environmental Toxicology and Chemistry. Vol. 12. pp 1813-1820. 

The Estimation Programs Interface (EPI) Suite.  Windows based suite of
physical/chemical properties and environmental estimation models
developed by the US EPA’s Office of Prevention, Pesticides, and Toxic
Substances (OPPTS) and Syracuse Research Institute (SRC).    HYPERLINK
http://www.epa.gov/opptintr/exposure/docs/EPISuitedl.htm 
http://www.epa.gov/opptintr/exposure/docs/EPISuitedl.htm 

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