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March 23, 2006

Number range CHAPTER**[MEMORANDUM]{.underline}**

SUBJECT: Inert Ingredient Dietary Risk Assessment for Linear Alkyl
Benzenesulfonate Reregistration Eligibility Document (RED)

Registration RED-4006-26242

DP# 324036

FROM: Kerry Leifer

Inert Ingredient Assessment Branch

Registration Division (7505C)

TO: Jennifer Slotnick, Chemical Review Manager

> RM Team 36

Regulatory Management Branch II

Antimicrobials Division (7510C)

and

Deborah Smegal

Reregistration Branch I

Health Effects Division (7509C)

As part of the overall risk assessment for Reregistration Case No. 4006:
benzenesulfonic acid, dodecyl- (CAS Reg. No. 27176-87-0); sodium
dodecylbenzenesulfonate (CAS Reg. No. 25155-30-0); and benzenesulfonic
acid, C10-16-alkyl derivs. (CAS Reg. No.68584-22-5), exposures resulting
from the active ingredient use of these substances (referred to
throughout this document as "linear alkylbenzenesulfonates") are
aggregated with exposures resulting from the use of the linear
alkylbenzenesulfonates as inert ingredients. This memorandum includes an
assessment of dietary exposures (including both food and drinking water)
for the inert ingredient uses of benzenesulfonic acid, dodecyl- (CAS
Reg. No. 27176-87-0); sodium dodecylbenzenesulfonate (CAS Reg. No.
25155-30-0); and benzenesulfonic acid, C10-16-alkyl derives. (CAS Reg.
No.68584-22-5) to be utilized for reregistration risk assessment
purposes.

**[Background]{.underline}**

Benzenesulfonic acid, dodecyl- (CAS Reg. No. 27176-87-0); sodium
dodecylbenzenesulfonate (CAS Reg. No. 25155-30-0); and benzenesulfonic
acid, C10-16-alkyl derives. (CAS Reg. No.68584-22-5) each have use as
pesticide inert ingredients (surfactants) in a number of food use and
nonfood use pesticide products. In the case of the food uses of these
substances, their food residues are considered exempt from the
requirement of a tolerance based on these substances being part of a
group of alkyl benzenesulfonates for which an exemption from the
requirement of a tolerance exists under the 40 CFR §180.910 and40 CFR
§180.930 listings of "Alkyl (C8-C24) benzenesulfonic acid and its
ammonium, magnesium, potassium, sodium, and zinc salts" summarized in
Table 1 below.

+----------------+---------+----------+--------------------------------+
| **Table 1.     |         |          |                                |
| Tolerance      |         |          |                                |
| Exemptions for |         |          |                                |
| Linear         |         |          |                                |
| Alkylbe        |         |          |                                |
| nzensulfonates |         |          |                                |
| as Inert       |         |          |                                |
| Ingredients**  |         |          |                                |
+================+=========+==========+================================+
| **Tolerance    | **CAS   | **40 CFR | **Use Pattern (Pesticidal)**   |
| Exemption      | Reg.    | § 180.** |                                |
| Expression/**  | No.**   |          |                                |
|                |         |          |                                |
| **Chemical     |         |          |                                |
| Name**         |         |          |                                |
+----------------+---------+----------+--------------------------------+
| Alkyl (C8-C24) | \-\--   | 910      | Surfactants, related adjuvants |
| b              |         |          | of surfactants                 |
| enzenesulfonic |         |          |                                |
| acid and its   |         |          |                                |
| ammonium,      |         |          |                                |
| calcium,       |         |          |                                |
| magnesium,     |         |          |                                |
| potassium,     |         |          |                                |
| sodium, and    |         |          |                                |
| zinc salts.    |         |          |                                |
+----------------+---------+----------+--------------------------------+
|                |         | 930      | Surfactants, emulsifier,       |
|                |         |          | related adjuvants of           |
|                |         |          | surfactants                    |
+----------------+---------+----------+--------------------------------+

**[Inert Ingredient Dietary Risk Assessment for Linear Alkyl
Benzenesulfonate]{.underline}**

A. Exposure Assumptions

A dietary exposure analysis for the inert ingredient use of linear alkyl
benzenesulfonate (benzenesulfonic acid, dodecyl- (CAS Reg. No.
27176-87-0); sodium dodecylbenzenesulfonate (CAS Reg. No. 25155-30-0);
and benzenesulfonic acid, C10-16-alkyl derivs (CAS Reg. No.68584-22-5))

The dietary (food) assessment was conducted using the generic screening
model for estimating inert ingredient dietary exposure as a basis for
estimating linear alkyl benzenesulfonate dietary exposure. This form of
assessment is unrefined and extremely conservative in nature as the
screening model assumes that the inert ingredient is used on all
commodities, and that 100 percent of crops are treated with the inert
ingredient. Further, the model assumes finite residues for every
consumed commodity (including meat, milk, poultry and eggs) that is
included in the Dietary Exposure Evaluation Model (DEEM™). A complete
explanation of the assumptions used in the generic screening model for
estimating inert ingredient dietary exposure is given in Appendix A.

The drinking water exposure analysis is based on a derivation of
estimated upper bound drinking water concentrations from these
substances' use as pesticide inert ingredients from the FQPA Index
Reservoir Screening Tool (FIRST). The results of the FIRST modeling
analysis and the conservative assumptions utilized as inputs into the
inert ingredient drinking water exposure assessment model are provided
in Appendix B.

B.  Dietary Risk from Food

Based on the toxicity endpoints selected by the Toxicity Advisory Clinic
(TAC) in its meeting of January 8, 2006, a dietary risk assessment was
conducted for the inert ingredient linear alkyl benzenesulfonate. The
TAC did not select an endpoint for acute dietary exposures as no effects
are attributable to a single dose, therefore acute dietary (food) risk
estimate for the inert ingredient use of linear alkyl benzenesulfonate
was not performed. The TAC selected an endpoint for chronic dietary
exposure to linear alkyl benzenesulfonate of 0.5 mg/kg/day (cPAD= 0.5
mg/kg/day). The table below (Table 2) provides a summary of the results
of chronic dietary risk estimates for the inert ingredient use of linear
alkyl benzenesulfonate.

  -------------------- ----------- ------------- ----- ----------------------
  Table 2. Estimated                                   
  Chronic Dietary                                      
  Exposure for Linear                                  
  Alkyl                                                
  Benzenesufonate                                      
  (LABS)                                               

  Population Subgroup1 Generic     LABS                %cPAD
                       Estimated   Estimated           
                       Exposure,   Exposure,           
                       mg/kg/day   mg/kg/day           

  U.S. Population      0.120       0.1200        \-    24%
  (total)                                              

  All infants (\< 1    0.245       0.2450        \-    49%
  year)                                                

  Children (1-2 years) 0.422       0.4220        \-    84%

  Children (3-5 years) 0.310       0.3100        \-    62%

  Children (6-12       0.174       0.1740        \-    35%
  years)                                               

  Youth (13-19 years)  0.100       0.1000        \-    20%

  Adults (20-49 years) 0.087       0.0870        \-    17%

  Adults (50+ years)   0.086       0.0860        \-    17%

  Females (13-49       0.087       0.0870        \-    17%
  years)                                               

                                                       

  1Only representative                                 
  population subgroups                                 
  are shown.                                           

                                                       

  Rev 01/25/06                                         

                                                       

  cPAD                 0.5                             
  -------------------- ----------- ------------- ----- ----------------------

C.  Dietary Risk from Drinking Water

A January 18, 2006, memorandum from Talia Milano to Jennifer Slotnick
and Deborah Smegal entitled "Environmental Fate Assessment of
Alkylbenzene Sulfonates for the Registration Eligibility Document (RED)"
provided information on the environmental fate of linear alkyl
benzenesulfonates. Based on information presented in that assessment,
linear alkyl benzenesulfonates are water soluble, nonvolatile and
mobile, but also readily biodegradable. There are no readily available
data on the occurrence of linear alkyl benzenesulfonates in ambient or
treated drinking water. No ambient water quality criteria, drinking
water maximum contaminant levels or health advisory levels have been
established for these compounds by EPA's Office of Water*.* The
potential for transport into drinking water resulting from pesticide
inert ingredient uses of these substances do exist, therefore an
estimate of drinking water concentrations resulting from the inert
ingredient uses of these substances was conducted*.*

As noted above, the TAC did not select an endpoint for acute dietary
exposures as no effects are attributable to a single dose, therefore an
acute drinking water risk estimate for the inert ingredient use of
linear alkyl benzenesulfonate was not performed. The estimated chronic
drinking water concentration and drinking water level of concern for
chronic exposure to linear alkyl benzenesulfonates is given in Table 3
below.

+-----------------------+-----------------------+-----------------------+
| **Table 3. Chronic    |                       |                       |
| Drinking Water        |                       |                       |
| Exposure Estimates    |                       |                       |
| for Inert Ingredient  |                       |                       |
| Uses of Linear        |                       |                       |
| Alkyl**               |                       |                       |
|                       |                       |                       |
| *                     |                       |                       |
| *Benzenzesulfonates** |                       |                       |
+-----------------------+-----------------------+-----------------------+
| **Population          | **EDWC**^1^           | **DWLOC**^2^          |
| Subgroup**            |                       |                       |
|                       | **(µg/L)**            | **(µg/L)**            |
+-----------------------+-----------------------+-----------------------+
| U.S. Population       | 6.6                   | 38 -1,500             |
| (total)               |                       |                       |
+-----------------------+-----------------------+-----------------------+
| Children (1-2 years)  | 6.6                   | 8 - 500               |
+-----------------------+-----------------------+-----------------------+

1 Estimated Drinking Water Concentration (EDWC) for chronic drinking
water exposure as determined by the use of FIRST modeling analysis
described above. \[The EDWC for linear alkyl benzenesulfonates is the
value reported as the "Adjusted Annual Average (Chronic) Untreated Water
Concentration" in Appendix B\]

2 Drinking Water Level of Comparison (DWLOC) is the maximum contribution
from water allowed in the diet. In this case, since the allowable risk
contribution from food is based on a screening level model, the use of a
single, deterministic value for the DWLOC is not appropriate. Rather a
DWLOC range is given, with the values in the range corresponding to an
upper value of range of drinking water concentrations ranging from 100%
of the cPAD (i.e., assuming no food exposure) to a lower value that
considers food exposures to be at the dietary screening level value.

D.  Conclusions

Based on the use of the screening level inert ingredient dietary
exposure model and the selected chronic dietary exposure endpoint for
linear alkyl benzenesulfonates, there are no concerns for risks
associated with dietary (food) exposures as the estimated dietary
exposures for the U.S. population and all population subgroups are below
100% of the cPAD. It should again be noted that this screening level
dietary risk assessment is quite conservative in nature, and that the
dietary exposure to linear alkyl benzenesulfonates as inert ingredients
in pesticide products estimated herein would greatly exceed actual
dietary exposures as the uses and effective application rates of linear
alkyl benzenesulfonates[^1] as inert ingredients applied to crops are
far less than those uses and application rates utilized in the screening
model.

For chronic drinking water exposures to linear alkyl benzenesulfonates
as inert ingedients, the DWLOC range for chronic exposure is 38-1500
µg/L for the general U.S. population and 8-500 µg/L for children 1-2
years old. The EDWC used to assess chronic (non-cancer) dietary risk
from drinking water is 6.6 µg/L. The chronic estimated concentration is
below the DWLOCs for the general U.S. population and all population
subgroups. Drinking water risks, therefore, are not of concern.

Based on the use of screening level inert ingredient dietary exposure
model and the selected chronic dietary exposure endpoint for linear
alkyl benzenesulfonates as well as the estimated upper bound drinking
water concentrations from these substances' use as pesticide inert
ingredients derived from FIRST, there are no concerns for aggregate
dietary and drinking water exposures to linear alkyl benzenesulfonates
resulting from their use as pesticide inert ingredients.

APPENDIX A

**Dietary Exposure Model for Inert Ingredients**

A screening level model for predicting dietary (food) exposure to inert
ingredients was developed and is based on the following assumptions and
inputs:

[Model Assumptions]{.underline}

Actual crop-specific residue data for active ingredients can be utilized
as surrogate data for inert ingredient residue levels (including
secondary residues in meat, milk, poultry and eggs).

Inert ingredients are used on all crops and 100% of all crops are
"treated" with inert ingredients

No adjustment made for % of inert in formulation, application rate, or
multiple applications of different active ingredient formulations

Considers only preharvest applications

[Model Inputs]{.underline}

A group of 57 of the most "significant" active ingredients were
considered. These active ingredients included substances in the
insecticide (20) , fungicide (17), and herbicide class (20) and were
selected based on a overall ranking scheme that included the following
components:

Overall Use--Based on 1999 data for active ingredient use (in lbs/yr).
*(All herbicides at \>5 million lbs/yr and all fungicides and
insecticides at \> 1 million lbs/yr were included)*

Use on crops that are significant contributors to diet *(All a.i.s which
had substantial use on crops that make up the "Top 25\" kids diet were
included)*.

Use on specific crops (*crop-by-crop pesticide use information was
evaluated to identify the most frequently used active ingredients*)

Actual residue monitoring studies (active ingredients with the highest
frequency of detection)

[Model Construct]{.underline}

A DEEM™-type analysis was performed utilizing the highest established
tolerance level residue for each commodity. In those cases where DEEM
listed a commodity for which a published tolerance did not exist, the
input value was selected based on representative crops or other
"default" values (e.g, use of standard processing factors). A
DEEM-FCID™, Version 1.3 analyses were performed for both acute and
chronic dietary exposure scenarios and the results for each are given in
Table 1 and 2.

**DEEM-FCID™ Program and Consumption Information**

Generic inert ingredient acute and chronic dietary exposure assessments
were conducted using the Dietary Exposure Evaluation Model software with
the Food Commodity Intake Database (DEEM-FCID™, Version 1.3), which
incorporates consumption data from USDA's Continuing Surveys of Food
Intakes by Individuals (CSFII), 1994-1996 and 1998. The 1994-96 and 998
CSFII data are based on the reported consumption of more than 20,000
individuals over two non-consecutive survey days. Foods "as consumed"
(e.g., apple pie) are linked to EPA-defined food commodities (e.g.
apples, peeled fruit - cooked; fresh or N/S; baked; or wheat flour -
cooked; fresh or N/S, baked) using publicly available recipe translation
files developed jointly by USDA/ARS and EPA. Consumption data are
averaged for the entire U.S. population and within population subgroups
for chronic exposure assessment, but are retained as individual
consumption events for acute exposure assessment.

For chronic exposure and risk assessment, an estimate of the residue
level in each food or food-form (e.g., orange or orange juice) on the
food commodity residue list is multiplied by the average daily
consumption estimate for that food/food form. The resulting residue
consumption estimate for each food/food form is summed with the residue
consumption estimates for all other food/food forms on the commodity
residue list to arrive at the total average estimated exposure. Exposure
is expressed in mg/kg body weight/day. This procedure is performed for
each population subgroup.

For acute exposure assessments, individual one-day food consumption data
are used on an individual-by-individual basis. The reported consumption
amounts of each food item can be multiplied by a residue point estimate
and summed to obtain a total daily pesticide exposure for a
deterministic (Tier 1 or Tier 2) exposure assessment, or "matched" in
multiple random pairings with residue values and then summed in a
probabilistic (Tier 3/4) assessment. For this screening-level
assessment, only a Tier 1 analysis was performed.

[Use of Model in Inert Risk Assessment]{.underline}

The results of this model would likely represent an upper-bound estimate
of likely potential dietary exposure to an inert ingredient resulting
from preharvest use. These values could be compared to the expected
toxicity in a qualitative (Tier 1 substance) assessment, or, in those
cases where a bounding level risk assessment is necessary, these
exposure values could be compared to the selected toxicity endpoints in
a %PAD or MOE type approach (see Figure 1). In cases where this model
would yield dietary risk values below the level of concern, no further
refinements would be necessary, and the potential dietary exposure and
risk could be considered adequately characterized. If this model results
in dietary risk, above the level of concern, then additional data, use
limitations, and/or /further refinements would be necessary.
Additionally, the use of this model could allow apportionment of the
amount of remaining 'acceptable' risk to other routes of exposure.

Fictional Example of Use of Dietary Exposure Model in %PAD Approach

Dose selected= 500 mg/kg-bw/day

Uncertainty factor=1000

cPAD=0.5 mg/kg-bw/day

Dietary exposure=0.12 mg/kg/day

%cPAD=0.12 mg/kg/day/0.5 mg/kg-bw/day x100 =24

[Model Limitations and Areas for Further Consideration]{.underline}

*Actual inert ingredient residue levels*\--While the selected group of
active ingredients possesses some chemical structural diversity, could
inert ingredients (by virtue of their uptake into plants and
environmental persistence) differ greatly from active ingredients in
terms of the nature and magnitude of their plant and animal residues?
What about degradates--would they be of concern or need to be separately
assessed?

*Concentration of inert in formulation*\--Initial analysis of
"benchmark" products for many of the 57 most "significant" active
ingredients indicates that the concentration of the a.i  any single
inert ingredient. If this can be further confirmed, it may allow for a
"maximum % inert" adjustment to be used in the model.

*Differences in product use rate and impacts on residue level.*\--While
there are a few outliers, most of these a.i.'s are used in the 1-5 lb
(AI basis) per season use rate.

*"Generic"* *inert*--The model makes no distinction as to formulation
type or timing of application. It may be possible to develop other
models for more specific inert use (e.g., preemergent use only, soil
incorporation only).

*Residues in meat, milk, poultry and eggs*--This model used the highest
tolerance level residues for input into DEEM™, but it may be possible to
utilize residues in livestock feed items and chemical specific
information related to uptake or accumulation of secondary residues
develop a different set of values on a per inert basis for meat, milk,
poultry and eggs.

  ---------------------- ------------------------------------------------
  **Table 1. Estimated   
  Chronic Dietary        
  Exposure^1^ for a      
  Generic Inert**        

  Population Subgroup^2^ Estimated Exposure, mg/kg/day

  U.S. Population        0.12
  (total)                

  All infants (\< 1      0.245
  year)                  

  Children (1-2 years)   0.422

  Children (3-5 years)   0.31

  Children (6_12 years)  0.174

  Youth (13-19 years)    0.1

  Adults (20-49 years)   0.087

  Adults (50+ years)     0.086

  Females (13_49 years)  0.087
  ---------------------- ------------------------------------------------

^1^Exposure estimates are based on highest-tolerance-level residues of
high-use active ingredients for all food forms, including meat, milk,
poultry, and eggs.

^2^Only representative population subgroups are shown.

  ----------------------- --------------- --------------- ----------------
  **Table 2. Estimated                                    
  Acute Dietary                                           
  Exposure^1^ for a                                       
  Generic Inert.**                                        

  Population Subgroup^2^  Estimated                       
                          Exposure,                       
                          mg/kg/day                       

                          95^th^          99^th^          99.9^th^
                          Percentile      Percentile      Percentile

  U.S. Population (total) 0.336           0.643           1.164

  All infants (\< 1 year) 0.701           1.06            2.056

  Children (1-2 years)    0.939           1.382           2.106

  Children (3-5 years)    0.683           1.01            1.476

  Children (6_12 years)   0.395           0.563           0.827

  Youth (13-19 years)     0.239           0.357           0.815

  Adults (20-49 years)    0.199           0.295           0.468

  Adults (50+ years)      0.191           0.263           0.357

  Females (13_49 years)   0.198           0.287           0.415
  ----------------------- --------------- --------------- ----------------

^1^Exposure estimates are based on highest-tolerance-level residues of
high-use active ingredients for all food forms, including meat, milk,
poultry, and eggs.

^2^Only representative population subgroups are shown.

APPENDIX B

**Estimated Environmental Concentration (EEC) of Linear Alkyl
Benzenesulfonates in Untreated Drinking Water** **and Surface Water
Resulting from Use as Inert Ingredients**

[I. Drinking Water]{.underline}

Monitoring data were not available for surface or ground water,
therefore modeling was performed. In the absence of measured chemical
properties, known fate and transformation half-lives, and actual use and
usage information, Tier I models provide a conservative assessment of
exposures in which, under almost all conditions, are unlikely to be
exceeded. In addition, proper parameterization of higher tier models
necessitates measured fate and known usage data. Drinking water
exposures were estimated using the Tier I surface water exposure model
FQPA Index Reservoir Screening Tool (FIRST, Version 1.0, dated August 1,
2001). The Tier I ground water exposure model, Screening Concentrations
in Ground Water, was not used in this assessment because these compounds
are unlikely to result in exposures exceeding surface waster
concentrations when measured chemical property and fate data are used.
Modeling inputs for fate and transport of the linear alkyl
benzenesulfonates were assumed to be stable. This approach is expected
to be conservative, resulting in exposures that are unlikely to actually
occur in the environment based on physical-chemical inputs and
environmental fate and the application rate used. Compounds modeled as
stable and very mobile, result in exposures that will be linear with
increases in application rate or in numbers of applications. For
example, the exposures from a 2 pound application rate will be twice as
high from a 1 pound application rate, whether applied at once or
separated by time within a year. Environmental fate data and default
application rate information are presented in Table 1. The results of
the model were then scaled to adjust for an effective application rate
of 0.1 lbs/acre (based upon a linear alkyl benzenesulfonate weight
fraction of 5% (a \>95^th^ percentile value), a product application rate
of 1 lb/product acre and four applications per year).

  --------------------- ------------------ -------------------------------
  **Table 1. Linear                        
  Alkyl                                    
  Benzenesulfonate                         
  Modeling Input                           
  Parameters for FIRST                     
  and GENEEC**                             

  **Parameter**         **Value**          **Source**

  Maximum single        1                  Assumed.
  application rate                         
  (lb/acre)                                

  Application Method    Aerial Spray       No limits on application
                                           method; method yielding most
                                           conservative results used

  Max No. application   4                  Assumed
  per year                                 

  PCA factor (decimal)  0.87 (default)     Effland et al (2000)

  Kd (mL/g)             0.01               Assumed

  Aerobic soil met.     Stable^1^          Assumed
  t~1/2~ (d)                               

  Solubility (mg/L)     100000             assumed

  Aerobic aquatic met.  Stable^1^          assumed
  t~1/2~ (d)                               

  Hydrolysis (pH 7)     Stable^1^          assumed
  t~1/2~ (d)                               

  Aqueous photolysis    Stable^1^          assumed
  t~1/2~ (d)                               
  --------------------- ------------------ -------------------------------

^1^For the purpose of estimating a high-end surface water concentration,
linear alkyl benzenesulfonates are assumed to be stable to these
degradation pathways on the field and in surface water.

Drinking Water EEC Using FIRST:

RUN No. 1 FOR Generic ON Generic \* INPUT VALUES \*

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP

ONE(MULT) INTERVAL Kd (PPM ) (%DRIFT) AREA (IN)

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

1.000( 1.000) 1 1 .0\*\*\*\*\*\*\* AERIAL(16.0) 87.0 .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED

(FIELD) RAIN/RUNOFF (RESERVOIR) (RES.\_EFF) (RESER.) (RESER.)

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

1000.00 2 N/A .00\_ .00 .00 .00

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.0 AUG 1, 2001

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC)

CONCENTRATION CONCENTRATION

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

92.170 66.089

ADJUSTED UNTREATED WATER CONC (MICROGRAMS/LITER (PPB))

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC)

CONCENTRATION CONCENTRATION

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

9.217 6.609

.

III\. [Uncertainties]{.underline}

The FIRST model is designed to yield concentration values which exceed
those predicted by the linked EPA PRZM and EXAMS models for all but the
most vulnerable sites, application patterns and environmental fate
properties. PRZM/EXAMS predictions may exceed FIRST predictions under
the following circumstances:

> Applications to crops in managed environments known to produce
> excessive runoff (e.g., crops grown over plastic mulch).
>
> Applications at sites with hydrologic group D soils which also receive
> excessively high rainfall (e.g., EFED sweet potato scenario in
> southern Louisiana).
>
> Multiple applications over a window of 30 days or longer in
> exceptionally high rainfall areas (e.g., far southeastern US).

Linear alkyl benzenesulfonates were assumed to be stable in surface
water environments which likely overestimate actual concentrations given
the available information related to the ready biodegradability of
linear alkylbenzensulfonates.

[^1]: A survey of those products listed as containing the inert
    ingredients benzenesulfonic acid, dodecyl- (CAS Reg. No.
    27176-87-0); sodium dodecylbenzenesulfonate (CAS Reg. No.
    25155-30-0); and benzenesulfonic acid, C10-16-alkyl derivs (CAS Reg.
    No.68584-22-5) was conducted. The results of that survey indicate
    that the use of linear alkylbenzenesulfonates as inert ingredients
    is limited, as nearly all products that do contain linear
    alkylbenzenesulfonates as inert ingredients have a total linear
    alkyl benzenesulfonate content of less than 5% w/w. Additionally,
    the vast majority of the products that contain linear alkyl benzene
    sulfonates are herbicide products that typically are applied in a
    preemergent or early post-emergent fashion, use scenarios that
    result in little or no crop residues.