![](media/image1.png){width="1.5833333333333333in"
height="1.5416666666666667in"}**UNITED STATES ENVIRONMENTAL PROTECTION
AGENCY**

WASHINGTON, D.C. 20460

OFFICE OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

> April 13, 2006

**[MEMORANDUM]{.underline}**

**SUBJECT:** Environmental Fate Assessment of Alkyl\* dimethyl benzyl
ammonium chloride \*(50%C14, 40%C12, 10%C16) (ADBAC) for the
Reregistration Eligibility Decision (RED) Document

> **Case No.**: 0350-26186 **DP Barcode:** 322870

**FROM:** Srinivas Gowda, Microbiologist/Chemist

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510C)

**TO:** Mark Hartman, Branch Chief

Benjamin Chambliss, Team Leader

Najm Shamim, Risk Assessor

Regulatory Management Branch II

Antimicrobials Division (7510C)

Jacqueline McFarland, Chemical Review Manager

Regulatory Management Branch I

> Antimicrobials Division (7510C)

**THRU:** Siroos Mostaghimi, Acting Team Leader, Team one

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510C)

Norman Cook, Branch Chief

Risk Assessment and Science Support Branch (RASSB)

> Antimicrobials Division (7510C)

**[Chemical Name]{.underline}** **[PC Code]{.underline}**
[**CAS#**]{.underline} **[Common Name]{.underline}**

Alkyl\* dimethyl benzyl ammonium chloride 069105 68424-85-1 ADBAC

\*(50%C14, 40%C12, 10%C16)

Environmental Fate Science Chapter and Fate Assessment on ADBAC is
submitted for Reregistration Eligibility Decision (RED).

**ALKYL DIMETHYL BENZYL AMMONIUM CHLORIDE** **(ADBAC)**

**ENVIRONMENTAL FATE SCIENCE CHAPTER**

**EXECUTIVE SUMMARY**

ADBAC is used primarily as a disinfectant, a sanitizer, or as a
microbicide/microbiostat. It also serves as an algaecide,
bactericide/bacteriostat, fungicide/fungistat, insecticide, miticide,
virucide, defoliant, feeding depressant, repellent and tuberculocide.
Use sites for ADBAC include agricultural premises and equipment, food
handling, commercial, industrial and institutional settings, residential
areas or areas of public access, pets and kennels, medical facilities,
swimming pools, aquatic areas, and industrial water systems. ADBAC is
also used as a wood preservative. As an agricultural pesticide, ADBAC is
used for ornamental plants, shrubs, and vines. Some of the required
guideline studies for an environmental fate assessment have been
submitted. The Agency is using the available environmental fate studies
for fate assessment of ADBAC to fulfill the reregistration requirements.
Because of its use as a wood preservative, an aqueous availability study
evaluating the leachability of ADBAC from treated wood is required.
However, no data have been submitted to the Agency.

ADBAC is hydrolytically stable under abiotic and buffered conditions
over the pH 5-9 range. ADBAC is also stable to photodegradation in pH 7
buffered aqueous solutions. However, in the presence of a
photosensitizer (e.g., acetone), ADBAC has been shown to degrade with an
estimated half-life of 7.1 days.

Aquatic metabolism studies under aerobic and anaerobic conditions
indicate that ADBAC is stable to microbial degradation. ADBAC did not
degrade in flooded sand loam soil that was incubated at 24-27C in the
dark for up to 30 days in an aerobic aquatic metabolism study. Under
anaerobic conditions, ADBAC was found to be very resistant to
degradation with a calculated half-life of 1,815 days. However, a report
on the biodegradability of ADBAC prepared by the Registrant concluded
that the degree of ADBAC biodegradability is variable and is influenced
by the chemical concentration, alkyl chain length, the presence of
anionic moieties and the quantity and characteristics of the microbial
population. According to this report, ADBAC is biodegradable and
environmentally acceptable. This report was based on information from
the open literature, unpublished sources, and meeting proceedings and
has not been reviewed by the Agency.

ADBAC is immobile in soil. The available soil mobility study shows that
ADBAC has a strong tendency to bind to sediment/soil with Freundlich
K~ads~ values were 6,172 for the sand soil, 10,797 for the silt loam,
5,123 for the sandy loam soil, and 32,429 for the clay loam and the
corresponding K~oc~ values were 6,171,657 for the sand soil, 2,159,346
for the silt loam, 640,389 for the sandy loam soil, and 1,663,039 for
the clay loam. Because of its strong adsorption to soils, ADBAC is not
expected to contaminate surface and ground waters.

Bioaccumulation of ADBAC in freshwater fish is not likely to occur.
Maximum bioconcentration factors (BCF) were 33X for edible tissues
(muscle, skin), 160X for nonedible tissues (viscera, head, carcass), and
79X for whole fish tissues. ADBAC is not expected to pose a concern for
bioconcentration in aquatic organisms.

**I. [Environmental Fate Assessment]{.underline}**

A. Abiotic

In a hydrolysis study conducted under abiotic and buffered conditions,
alkyl dimethyl benzyl ammonium chloride (ADBAC), did not hydrolyze at pH
9 (estimated half-life = 379 days) and appeared hydrolytically stable at
pH 5 and 7 (estimated half-lives = 150-183 days). The study was
conducted at 25 ± 1C for up to 30 days. The hydrolysis data
requirements (OPP 161-1) for ADBAC have been fulfilled by this study
(MRID 408356-02).

The photodegradation potential of ADBAC was investigated in sensitized
and nonsensitized buffer solutions adjusted to pH 7 \[0.2 M
tris(hydroxyl methyl) amino methane\]. ADBAC did not degrade in the pH 7
sterile buffered aqueous solution that was continuously irradiated over
a 30-day period at 25C. In contrast, ADBAC degraded with an estimated
half-life of 7.1 days in a similar buffer solution that had been
sensitized with 1% acetone. ADBAC did not degrade in the dark controls
of the sensitized and non-sensitized solutions. An unidentified
degradate, isolated from the sensitized irradiated solution 30-days post
treatment, accounted for 74.5% of the applied radioactivity. Because of
missing information, the photodegradation in water guideline
requirements (OPP 161-2) have not been fulfilled by this study (MRID No.
408356-03).

B. Biotic

In a study on an aerobic aquatic system, ADBAC did not degrade in
flooded sand loam soil that was incubated at 24-27C in the dark for up
to 30 days. During the study, most of the applied radioactivity, of
which \> 90% was extractable, was observed in the soil fraction. The
aerobic aquatic metabolism guideline requirements (OPP 162-4) have been
fulfilled by this study (MRID 408356-04).

Under anaerobic conditions, ADBAC was found to be very resistant to
degradation in flooded sandy loam soil that had been incubated for a
year at 25C. The registrant-calculated half-life was 1,815 days. No
degradation products were found. This study satisfies the anaerobic
aquatic metabolism guideline requirements (OPP 162-3) (MRID Nos.
411055-01 & 424151-01).

A review of information from the open literature, unpublished sources
and meeting proceedings prepared by the Registrant indicates that ADBAC
is readily and ultimately degradable. The report author noted that the
aerobic and anaerobic aquatic metabolism studies for ADBAC were designed
to assess environmental fate of ADBAC based on outdoor applications of
agricultural chemicals, but not the direct biodegradability potential of
this chemical as a result of its use as an antimicrobial. Other
limitations of the tests were noted, such as loss of microbial activity
during air drying of soil material and limited gas exchange in the
aerobic test. According to this report, the degree of ADBAC's
biodegradability is variable and is influenced by the chemical
concentration, alkyl chain length, the presence of anionic moieties and
the quantity and characteristics of the microbial population. A
mechanism of biodegradation for ADBAC, in which several bacterial
species are needed for ultimate biodegradation of this compound, is also
described.

The adsorption/desorption characteristics of ADBAC were studied on four
representative agricultural soils: sand, sandy loam, silt loam, and clay
loam. The study determined ADBAC to be immobile in all soils tested.
Freundlich K~ads~ values were 6,172 for the sand soil, 10,797 for the
silt loam, 5,123 for the sandy loam soil, and 32,429 for the clay loam
and the corresponding K~oc~ values were 6,171,657 for the sand soil,
2,159,346 for the silt loam, 640,389 for the sandy loam soil, and
1,663,039 for the clay loam. Following the first desorption step,
Freundlich K~des~ values were 7,137 for the sand soil, 14,083 for the
silt loam soil, 96,540 for the sandy loam soil, and 165,556 for the clay
loam soil; corresponding K~oc~ values were 7,137,310 for the sand soil,
2,816,590 for the silt loam soil, 12,067,457 for the sandy loam soil,
and 8,490,062 for the clay loam soil. Since the study only provides
information on the mobility of unaged ADBAC, the adsorption/desorption
guideline requirements (OPP 163-1) have been partially fulfilled (MRID
Nos. 408356-05 & 424148-01).

A study consisting of a 35-day bioconcentration and a 21-day depuration
period was conducted to evaluate the bioconcentration of ADBAC in
bluegill sunfish under flow-through aquarium conditions. Analysis of
edible tissues (muscle, skin), whole fish, and nonedible tissues
(viscera, carcass) were performed throughout the exposure period.
Maximum bioconcentration factors (BCFs), based on total radioactivity,
were 33X for edible tissues, 79X for whole fish tissues and160X for
nonedible tissues. The maximum concentrations of residues occurred at
day 35 and were 3.4, 6.6, and 13 ppm for edible tissues, whole fish, and
nonedible tissues, respectively. After 21 days of depuration, ^14^\[C\]
residues were 2.4 ppm in edible tissues, 3.7 ppm in whole fish tissues,
and 5.3 ppm in nonedible tissues. ^14^\[C\] residues in edible tissues
did not decline significantly from the concentrations detected during
the exposure period. The study is scientifically valid, but it does not
satisfy the guidelines (OPP 165-4) for bioaccumulation in fish (MRID
410268-01) since residues present at 0.05 ppm or greater in the treated
water and fish were not identified.

**APPENDIX**

**Environmental Fate Data for ADBAC**

**A. [Environmental Fate Guideline Studies]{.underline}**

**1. Hydrolysis (OPP Guideline Number 161-1, MRID No. 408356-02)**

This study was reviewed by the Agency and found to be scientifically
valid. The hydrolysis data requirements for ADBAC have been fulfilled.

Uniformly ring-labeled \[^14^C\]ADBAC (alkyl dimethyl benzyl ammonium
chloride; radiochemical purity 98%; specific activity 2.03 x 10^4^
dpm/μg), diluted with nonradiolabeled ADBAC and deionized water, was
added at 1,298 μg/flask to sterile pH 5 (acetic acid), pH 7
\[N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid (HEPES)\], pH 7
\[tris(hydroxymethyl)aminomethane- (TRIS)\] and pH 9 (boric acid)
aqueous buffer solutions. Acetonitrile was added to the buffer solutions
as a cosolvent at \< 1%. The final nominal concentration of
\[^14^C\]ADBAC in the treated solutions was 9.7 μg/ml. Aliquots of the
treated buffer solutions were added to amber-colored silanized vials.
The vials were capped and incubated in the dark at 25 ± 1C for 30 days.
Duplicate samples were collected at 0, 1, 3, 7, 14, 22 and 30 days post
treatment.

At each sampling interval, duplicate aliquots of the buffer solutions
were analyzed for total radioactivity by liquid scintillation counting
(LSC). Sample solutions were also analyzed for specific \[^14^C\]
compounds by one-dimensional TLC on silica gel plates developed in a
chloroform:methanol:formic acid (60:40:2, v:v) solvent system. A
radioscanner was used to locate radioactive areas on the plates.
Autoradiographs were prepared from the 0- and 30-day TLC plates. After
scrapping radioactive areas from the plates, the radioactivity was
desorbed and quantified by LSC. The pH of each solution was also
measured at each sampling interval.

Uniformly ring-labeled \[^14^C\]ADBAC, at a nominal concentration of 9.7
μg /ml, was relatively stable to hydrolysis in pH 5 and 7 buffer
solutions (half-lives were 150-183 days), decreasing by ≤ 2.3% of the
recovered radioactivity during 30 days of incubation. \[^14^C\]ADBAC did
not hydrolyze in pH 9 buffer solution; the half-life was calculated to
be 379 days.

In the buffer solutions, the parent was present at 89.5 -- 92.8% of the
applied radioactivity at 30 days post treatment. The original containers
for all individual samples with less than 90% recovery were further
extracted with methanol. The 30-day mass balance increased to 92.2-97.4%
of the applied radioactivity when the methanol rinse of the vials was
analyzed. The pH of all buffer solutions remained stable throughout the
study period.

**2. Photodegradation in Water (OPP Guideline No. 161-2, MRID No.
408356-03)**

This photodegradation study was reviewed by the Agency and found
scientifically valid. However, in its original review the Agency
concluded that the study did not meet guideline requirements since
information on characterization of the light source was not reported and
one \[^14^C\] compound isolated 30 days post treatment from the
sensitized irradiated solution at 74.5% (6.97 ppm) of the applied
radioactivity was not identified. Supplemental information (MRID
424152-01) submitted by the Registrant provided information on the light
source; however, the identity of the degradate was not reported. The
Agency noted that there are many organic photosensitizers in the
environment, so it is important to identify the major photoproduct that
was detected in the photosensitized system (EFGB, 1993). The
photodegradation in water guideline requirements for ADBAC have not been
fulfilled. This study is classified as upgradable.

In this study, ring-labeled \[^14^C\]ADBAC (alkyl dimethyl benzyl
ammonium chloride; radiochemical purity 98%; specific activity 2.03 x
10^4^ dpm/μg), diluted with nonradiolabeled ADBAC and deionized water,
was added to two flasks containing sterile pH 7 buffer solution
(tris(hydroxy methyl) amino methane) prepared with \< 1% acetonitrile as
cosolvent. The solution in one flask was photosensitized with 1% acetone
(v:v). Final concentrations of \[^14^C\]ADBAC were 9.11 ppm and 9.35 ppm
in the nonsensitized solution and sensitized solution, respectively.

Aliquots of the treated solutions were transferred to capped culture
tubes. Half of the vials containing each solution were covered with
aluminum foil and stored inside a closed box (dark control solutions).
The box was placed along with the unwrapped vials in a photolysis
apparatus. A xenon lamp, characterized as having approximately one-half
the intensity of sunlight, was used to irradiate the samples. The
temperature in the photolysis chamber was maintained at 25 ± 1C.
Duplicate samples of irradiated and dark control solutions were removed
for analysis at approximately 0, 1, 3, 7, 10, 14, 21, and 30 days post
treatment.

At each sampling interval, duplicate samples of irradiated and dark
control solutions were analyzed without extraction for total
radioactivity by liquid scintillation counting (LSC). The aliquots were
also analyzed for specific \[^14^C\] compounds using one-dimensional TLC
on silica gel plates developed in a chloroform:methanol:formic acid
(60:40:2, v:v) solvent system. A radioscanner was used to locate
radioactive areas on the plates. In addition, autoradiographs were
prepared from the 0- and 30-day TLC plates. After scrapping radioactive
areas from the plates, the radioactivity was desorbed and quantified by
LSC. The pH of each solution was measured at each sampling interval. The
volatilization of \[^14^C\] residues from the irradiated and dark
control samples was also measured by analyzing the trapping solutions at
0, 1, 3, 7, 10, 14, 21, and 30 days post treatment for total
radioactivity using LSC.

Ring-labeled \[^14^C\]ADBAC (alkyl dimethyl benzyl ammonium chloride;
radiochemical purity 98%; specific activity 2.03 x 10^4^ dpm/μg), at
approximately 9 ppm, did not degrade in a sterile buffer solution that
was irradiated continuously for 30 days with a xenon light source and
maintained at 25 ± 1C or in a sterile buffer solution used as dark
control. \[^14^C\]ADBAC accounted for \> 99% of the applied
radioactivity at 30 days post treatment in the sterile buffer solutions.
During the study, the material balance of the sterile buffer solutions
ranged from 96.3 to 105% of the applied radioactivity. In contrast,
\[^14^C\]ADBAC degraded with a calculated half-life of 7.1 days in the
irradiated solution that had been sensitized with 1% acetone. The parent
compound declined from 76.9% of the applied radioactivity at 3 days post
treatment to approximately 37% at 7 and 10 days, and 16.3% at 30 days
post treatment. An unidentified degradate accounted for 74.5% of the
applied radioactivity. \[^14^C\]ADBAC did not degrade in the sensitized
dark control. The material balance of the sensitized solutions ranged
from 90.3 to 101% of the applied radioactivity during the study.
Volatilization of \[^14^C\] residues from the sensitized and
nonsensitized buffered solutions accounted for 3.4-5.4% of the applied
radioactivity during 30 days of incubation.

**3. Anaerobic Aquatic Metabolism (OPP Guideline No. 162-3, MRID Nos.
411055-01 & 424151-01)**

This anaerobic aquatic metabolism study was reviewed by the Agency and
found to be acceptable after supplemental information was submitted by
the Registrant (MRID No. 424151-02) (EFGB, 1993). The anaerobic aquatic
metabolism data requirement for ADBAC has been satisfied. Information
was extracted directly from the study report with minor editing changes.

In this study, samples of well water and sandy loam soil, preincubated
under anaerobic conditions for 34 days, were fortified with
\[^14^C\]ADBAC at a nominal test concentration of 10 μg/g. The fortified
samples were placed in metabolism vessels in an environmental chamber
maintained at an average temperature of 25.2 ± 0.5C under dark
conditions. The treatment samples were incubated anaerobically for one
year following dosing. In addition to the day 0 soil and water analysis,
samples of soil, water and trapping solutions were collected for
analysis at 1, 3, 7, 14 days post treatment and 1, 2, 3, 4, 6, 9 and 12
months post treatment. Trapping solutions were also sampled at 5, 7, 8,
10, and 11 months.

On each sample day, sample tubes were vortexed and centrifuged to
separate the water layer from the soil. The aqueous phase was pippetted
into a separate silanized tube and adjusted to volume with deionized
water. The remaining soil in each tube was extracted three times with
dimehtylformamide:acetic acid. Triplicate aliquots of the both the
aqueous phase and soil extracts were analyzed by liquid scintillation
counting (LSC) to determine total radioactivity. Bound residues were
determined by combustion of triplicate aliquots of the post-extracted
soil followed by LSC analysis. The trapping solutions were also analyzed
in triplicate by LSC. Thin-layer chromatography (TLC) was used to
characterize \[^14^C\]residues in the samples.

Throughout the year-long study, \[^14^C\]residues levels in the water
remained low ranging from 0.7 to 2.4% of the total residues (mean value
of 1.2 ± 0.4%). The non-extractable residues of \[^14^C\]ADBAC accounted
for 10.9% of the total residues at the end of the study. Volatilization
of \[^14^C\]residues was minimal with only 0.3% of the applied dose
present in the volatile trap samples after 366 days of anaerobic
incubation.

The parent compound was the only compound detected in the TLC analysis
of the soil extracts. The recovery of \[^14^C\]-activity from the
thin-layer plates ranged from 89.1 to 106.1% of the applied
radioactivity (mean of 96.1 ± 4.2%). Most of the radioactivity recovered
was in the zone corresponding to the co-chromatographed parent compound.
The mean recovery as parent compound was 94.8 ± 4.3%. Based on the
levels of ADBAC present in the extractable residues, the half-life was
determined to be 1,815 days. The mass balance ranged from 100 to 112 %
of the measured day 0 levels (mean of 106 ± 4%).

**4. Aerobic Aquatic Metabolism (OPP Guideline No. 162-4, MRID No.
408356-04)**

This aerobic aquatic metabolism study was reviewed by the Agency and
found scientifically valid. In its original review the Agency noted that
the study did not meet guideline requirements since several \[^14^C\]
residues present at ≥ 0.01 ppm were not identified, including one
degradate present at 0.12 μg/g and the composite of all the scraped TLC
material known as "remainder" that accounted for up to 0.97 μg /g.
Supplemental information (MRID 424149-01) submitted by the Registrant
indicated that the degradate represents only a minor impurity, not a
metabolic degradate, and was not detected after day 2. In addition, the
"remainder" fraction contained only nondistinct components that were
less than 1% of the initial dose. After review of the supplemental
information, the Agency concluded that the study is acceptable and
satisfies the aerobic aquatic metabolism data requirement for ADBAC
(EFGB, 1993).

In this study, samples (10 g) of sieved (2 mm) sandy loam soil (64%
sand, 20% silt, 16% clay, 1.6% organic matter, pH 6.2, CEC 9.5 meq/100
g) were weighed into silanized culture tubes and then flooded with 20 ml
of well water that had been treated with approximately 10 μg/ml of
ring-labeled \[^14^C\]ADBAC (alkyl dimethyl benzyl ammonium chloride;
radiochemical purity 98%; specific activity 2.03 x 10^4^ dpm/μg). The
treated soil:water samples were homogenized and divided between two 3-L
glass metabolism vessels. Humidified air was pumped continuously into
the vessels holding the tubes of soil; effluent air was then passed
through an ethylene glycol trap, a 1 N sulfuric acid trap and two 1 N
potassium hydroxide traps. The test tubes were maintained at 24-27C
under dark conditions. One sample was collected from each metabolism
vessel at 0, 1, 2, 7, 14, 21, and 30 days post treatment. Volatile traps
were sampled at the same intervals.

At each sampling interval, soil:water samples were vortexed and
centrifuged and the aqueous phase decanted. Aliquots of the aqueous
phase were analyzed for total radioactivity by liquid scintillation
counting (LSC) and for specific compounds using normal-phase thin layer
chromatography (TLC) on silica gel plates developed in
chloroform:methanol:formic acid (60:40:20). The soil fraction was
extracted three times with dimethylformamide:acetic acid (80:20); the
extracts were separated from the soil by centrifugation and combined.
Aliquots of the extracts were analyzed for total radioactivity by LSC
and for specific compounds using normal-phase TLC as described for the
aqueous phase aliquots. Unextractable \[^14^C\] residues in the soil
were quantified by LSC following combustion. Residues were corrected for
combustion recovery efficiencies in controls. Radioactivity in the
volatile trapping solutions was quantified by LSC.

Ring-labeled \[^14^C\] ADBAC, at approximately 10 μg/g, did not degrade
in aerobic flooded sandy loam soil that was incubated in the dark at
24-27C for 30 days. During the study, the soil fraction contained
9.19-10.34 μg of radioactivity/g while the aqueous fraction contained
0.095-0.204 μg of radioactivity/g, with no definitive pattern. More than
90% of the radioactivity in the soil fraction was extractable. In the
soil fraction, there was a steady decrease from day 0 to day 30 in the
concentration of extractable radioactivity associated with the origin
(from 0.78 to 0.0% of the recovered radioactivity from the TLC plate),
with an unidentified \[^14^C\] compound at R~f~ 0.15 (from 0.92 to 0%),
and with the remainder radioactivity (from 11.3 to 1.63%). The remainder
radioactivity was defined as all radioactivity on the TLC plate that was
not associated with the origin, ADBAC, or the unknown at R~f~ 0.15. The
concentration of extractable \[^14^C\]ADBAC (R~f~ 0.4) increased from
87.0% at day 0 to 98.4% of the recovered radioactivity at day 30.
Unextractable \[^14^C\] residues in the soil fraction increased in
concentration from 0.272 μg/g at day 0 to 0.520 μg/g at day 30. In the
water fraction, \[^14^C\]ADBAC accounted for 68.1- 86.3% of the
radioactivity recovered from the TLC plate while the origin material and
"remainder" comprised 0.92-4.19% and 10.9-27.7%, respectively. Volatiles
accounted for a small fraction of the radioactivity (1.36 μg) at day 30.
Recoveries from the TLC plates ranged from 86.4-104% of the applied
radioactivity during the 30 day study. The material balance during the
study ranged from 96.1 to 103.4% of the nominal application rate.

**5. Adsorption/Desorption (OPP Guideline No. 163-1, MRID Nos. 408356-05
& 424148-01)**

This adsorption/desorption study was reviewed by the Agency and found
scientifically valid. However, the study only provides information on
the mobility of unaged ADBAC. The adsorption/desorption data
requirements for ADBAC has been partially fulfilled.

Based on the results of a preliminary study of the adsorption of
ring-labeled \[^14^C\]ADBAC to sand, sandy loam, silt loam, and clay
loam soils, a soil:solution ratio of 1:200 and an equilibration period
of 20 hours were chosen for the definitive adsorption and desorption
study.

In the definitive study, sand, silt loam, sandy loam, and clay loam
soils were sieved (10 mesh screen) and sterilized by autoclaving at 250
°F (121 °C) and 15 psi for 1 hour. Uniformly ring-labeled \[^14^C\]ADBAC
was purified to 98.4%, as determined by TLC/radiochemical analysis, and
mixed with non-radiolabeled ADBAC (specific activity 2.03 x 10^4^
dpm/μg).

For the adsorption phase of the study, subsamples of each soil were
weighed into nalgene bottles and mixed with 0.01 M CaCl~2~ solution. The
soil:solution slurries (1:200) were individually treated at nominal
concentrations of 0.1, 0.5, 1.0, and 2.0 µg/ml with \[^14^C\]ADBAC.
After shaking the bottles for 20 hours in the dark at 25 ± 1C
(adsorption equilibration period), the soil:solution slurries were
centrifuged and aliquots of the supernatant were analyzed for total
radioactivity by liquid scintillation counting (LSC).

For the desorption phase of the study, 196 ml of 0.01M CaCl~2~ were
added to each sample. The soil:solution slurries were shaken for 14
hours and 45 minutes and centrifuged. Aliquots of the supernatant were
analyzed for total radioactivity by LSC. The soil was air dried and
analyzed for total radioactivity by LSC following combustion.

Uniformly phenyl ring-labeled \[^14^C\]ADBAC, at approximately 0.1, 0.5,
1.0, and 2.0 µg/ml, was determined to be immobile in sterilized sand,
silt loam, sandy loam, and clay loam soil:solution slurries (1:200) that
were equilibrated in the dark for 20 hours at 25 ± 1C. Freundlich
K~ads~ values were 6,172 for the sand soil, 10,797 for the silt loam,
5,123 for the sandy loam soil, and 32,429 for the clay loam and the
corresponding K~oc~ values were 6,171,657 for the sand soil, 2,159,346
for the silt loam, 640,389 for the sandy loam soil, and 1,663,039 for
the clay loam. Following the first desorption step, Freundlich K~des~
values were 7,137 for the sand soil, 14,083 for the silt loam soil,
96,540 for the sandy loam soil, and 165,556 for the clay loam soil;
corresponding K~oc~ values were 7,137,310 for the sand soil, 2,816,590
for the silt loam soil, 12,067,457 for the sandy loam soil, and
8,490,062 for the clay loam soil. Material balances ranged from 71.66 to
123.43%.

It should be noted that the soils tested in this study were sterilized
by autoclaving prior to the experiment. Autoclaving affects the physical
and chemical properties of the soils. However, the Registrant noted that
at the time the protocol was developed, the use of autoclaved soils was
a generally accepted practice. It was also noted that autoclaving is
expected to enhance the apparent mobility of the chemical; however, the
results of the study showed that ADBAC is immobile. The Agency concluded
that the results are acceptable (EFGB, 1993).

6.  **Aquatic Field Dissipation (OPP Guideline No. 164-2)**

The Agency has waived data requirements for an aquatic field dissipation
study for ADBAC.

**7. Bioaccumulation in Fish (OPP Guideline No. 165-4, MRID No.
410268‑01)**

This bioaccumulation study was reviewed by the Agency and found
scientifically valid. However, the study does not meet guidelines for
the fulfillment of data requirements for ADBAC on the bioaccumulation in
fish since \[^14^C\]residues present at 0.05 ppm or greater in the
treated water and fish tissues were not characterized. This study was
classified by the Agency as supplemental (EFGB, 1993).

Bluegill sunfish (*Lepomis macrochirus*; average length 65 mm, average
weight 3.6 g) were maintained in a cultured tank under a light/dark
cycle of 16 hours/8 hours for at least 14 days prior to the initiation
of the study. Flow-through aquatic exposure systems were prepared using
two 75-L aquaria (one exposure and one control). Each aquarium was
continuously supplied with well water (pH 6.9-7.1, dissolved oxygen
78-88% of saturation, hardness 24-28 mg/L as CaCO~3~, alkalinity 19-22
mg/L as CaCO~3~, temperature 18 °C) at a flow rate of 10 turnovers per
day. Bluegill sunfish (190) were placed in each aquarium. The exposure
aquarium was continuously treated with ring-labeled \[^14^C\]ADBAC
(alkyl dimethyl benzyl ammonium chloride; radiochemical purity 98.9%,
specific activity 227013 dmp/μg) combined with unlabeled ADBAC (30.64%
active), at a concentration of 0.05 ppm.

Water samples were collected from the exposure and control aquaria prior
to introducing the fish and at days 1, 3, 7, 8, 9, 10, 14, 21, 23, 28
and 35. During the exposure period, five fish were collected from the
exposure aquarium at days 1, 3, 7, 10, 14, 21, 28 and 35. Fish were
collected from the control aquarium at days 0, 9, and 35.

Following a 35-day exposure period, 35 of the fish remaining in the
exposure aquarium were transferred to an aquarium containing untreated
water for a 21-day depuration period. Water samples and
\[^14^C\]ADBAC-treated fish (5) were collected during the depuration
period on days 1, 3, 7, 10, 14, 16 and 21. Control fish were collected
on day 21.

At each sampling interval, water samples were analyzed for total
radioactivity by liquid scintillation counting (LSC). The detection
limit was 0.014 ppm.

Fish from the exposure and depuration periods were dissected and
separated into edible tissues (muscle and skin) and nonedible tissues
(viscera, head and carcass). The edible and nonedible fractions were
analyzed for total radioactivity by LSC following combustion; the limit
of detection was 0.1 ppm. The edible tissue fractions from additional
fish (three sets of ten fish) collected after 35 days of exposure were
homogenized with dry ice and extracted with hexane followed by methanol.
The extracts were analyzed by LSC while the unextractable radioactivity
remaining in the tissues were quantified by LSC following combustion. In
addition, the skins from ten additional fish also collected after 35
days of exposure were analyzed for radioactivity by combustion to
determine if external surface binding of the test substance had
occurred.

Radiolabeled residues accumulated in bluegill sunfish that were exposed
for 35 days to uniformly phenyl-ring labeled \[^14^C\]ADBAC, at a
concentration of 0.05 ppm, under flow-through aquarium conditions.
Maximum bioconcentration factors (BCF) were 33X for edible tissues
(muscle, skin), 160X for nonedible tissues (viscera, head, carcass), and
79X for whole fish tissues. The maximum concentrations of
\[^14^C\]residues (day 35) were 3.4, 13 and 6.6 ppm in edible tissues,
nonedible tissues and whole fish, respectively.

Of the total radioactivity found in the edible tissues, 1.2-4.2% was
extractable into hexane and 6.7-18.5% was extractable into methanol.
Unextractable radioactivity accounted for 72-89.3% of the total
radioactivity in edible tissues. \[^14^C\]ADBAC at concentrations of
2.7-6.4 ppm was determined in the skin of fish after 35 days of
exposure.

After 21 days of depuration, ^14^\[C\] residues were 2.4 ppm in edible
tissues, 5.3 ppm in nonedible tissues, and 3.7 ppm in whole fish
tissues. ^14^\[C\] residues in edible tissues did not decline
significantly from the concentrations detected during the exposure
period.

**8. Aqueous Availability (Leachability) (American Wood-Preservers'
Association Standard Method E11-97 "Standard Method for Determining the
Leachability of Wood Preservatives, None)**

Because of its use as a wood preservative, an aqueous availability study
evaluating the leachability of ADBAC from treated wood is required.
However, no data have been submitted to the Agency.

**9. Assessment of the Biodegradability of ADBAC and DDAC (No MRID
Number)**

This report is an assessment of the biodegradability of ADBAC and DDAC
based on the review of information from the open literature, unpublished
sources and meeting proceedings. It also provides a summary of the
current information available on the environmental fate of ADBAC and
DDAC. The report was submitted by the registrant to EPA, but has not
been reviewed by the Agency.

Based on the review of the studies in the report, Lee (1992) concluded
that:

"Results of studies published in the open literature, literature
reviews, conference proceedings and information obtained from
unpublished sources indicate that ADBAC and DDAC are biodegradable with
the rate and extent of degradation influenced by quat concentration,
alkyl chain length, the presence of anionic moieties, and the type of
microbes. These factors and the design of the test system are important
in interpreting the reliability of biodegradability test results.

After release of ADBAC and DDAC to domestic waste streams or in the open
environment, a combination of physical and chemical properties, in
addition to biodegradability, influence their fate through the
environmental compartments of air, water, soil/sediment and biota.
Important properties for evaluating the environmental fate of these
materials include solubility, vapor pressure, surface activity and
adsorptive properties."

In a study by Dobbs et al., 1995, biodegradation was studied under
aerobic conditions using the CO~2~ production test. The OECD guideline
used states that if \>60% of the theoretical CO~2~ is produced in 28
days, then the chemical is considered readily biodegradable. The results
show that 65.9% of the possible theoretical CO~2~ was released in 29
days in the 10 mg/L ADBAC treatment, but only 6.8% was released in the
20 mg/L ADBAC treatment. The authors suggest that the treatment at the
lower concentration indicates that ADBAC is readily biodegradable, but
that at the higher concentration is bactericidal. Use of ADBAC as a
molluscicide is suggested at concentrations of 2.5 mg/L. Therefore, the
authors concluded that results of this test suggest that ADBAC would be
biodegradable under the conditions specified for its use.

**BIBLIOGRAPHY**

**[MRID]{.underline} [Citation]{.underline}**

408356-02 Carpenter, M. and M. Fennessey. 1988. Hydrolysis of ADBAC as a
function of pH at 25°. ABC Amended Final Report \# 35712. Unpublished
study performed by Analytical Bio-Chemistry Laboratories, Inc.,
Columbia, MO, and submitted by Chemical Specialties Manufacturers
Association, Washington, DC.

408356-03 Carpenter, M. and M. Fennessey. 1988. Determination of the
photolysis rate of ADBAC in pH 7 buffered solution at 25° C. ABC Final
Report #35713. Unpublished study performed by Analytical Bio-Chemistry
Laboratories, Inc., Columbia, MO, and submitted by Chemical Specialties
Manufacturers Association, Washington, DC.

408356-04 Daly, D. and W. Cranor. 1988. Aerobic aquatic metabolism of
alkyl dimethyl benzyl ammonium chloride. ABC Final Report #35715.
Unpublished study performed by Analytical Bio-Chemistry Laboratories,
Inc., Columbia, MO, and submitted by Chemical Specialties Manufacturers
Association, Washington, DC.

408356-05 Daly, D. and W. Cranor. 1992. Soil/Sediment
Adsorption-Desorption of Alkyl Dimethyl Ammonium Chloride. Performed by
ABC Laboratories, Inc., Columbia, Missouri. Submitted by ADBAC Joint
Venture/Chemical Specialties Manufacturers Association, Washington, DC.

410268-01 Flacker, P. 1989. Bioconcentration and elimination of
^14^C-residues by bluegill (*Lepomis macrochirus*) exposed to alkyl
dimethyl benzyl ammonium chloride (ADBAC). Study No.
11572-0287-6103-140B, Report No. 89-1-2921. Unpublished study performed
by Springborn Life Sciences, Inc., Wareham, MA, and submitted by ADBAC
Quat Joint Venture/Chemical Specialties Manufacturers Assoc.,
Washington, DC.

411055-01 Daly, D. and W. Cranor. 1989. Anaerobic aquatic metabolism of
alkyl dimethyl benzyl ammonium chloride. ABC Amended Final Report
#35714. Unpublished study performed by Analytical Bio-Chemistry
Laboratories, Inc., Columbia, MO, and submitted by ADBAC Joint
Venture/Chemical Specialties Manufacturers Association, Washington, DC.

424148-01 Daly, D. and W. Cranor. 1992. Soil/Sediment
Adsorption-Desorption of Alkyl Dimethyl Ammonium Chloride. Supplement in
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Columbia, Missouri. Submitted by ADBAC Joint Venture/Chemical
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424149-01 Daly, D. and W. Cranor. 1992. Aerobic metabolism of alkyl
dimethyl benzyl ammonium chloride. Supplement in support of MRID#
408356-04. Performed by ABC Laboratories, Inc., Columbia, Missouri.
Submitted by ADBAC Joint Venture/Chemical Specialties Manufacturers
Association, Washington, DC.

424151-01 Daly, D. and W. Cranor. 1989. Anaerobic aquatic metabolism of
alkyl dimethyl benzyl ammonium chloride. ABC Amended Final Report
#35714. Supplement in support of MRID# 411055-01. Unpublished study
performed by Analytical Bio-Chemistry Laboratories, Inc., Columbia, MO,
and submitted by ADBAC Joint Venture/Chemical Specialties Manufacturers
Association, Washington, DC.

424151-02 Daly, D. and W. Cranor. 1992. Anaerobic metabolism of alkyl
dimethyl benzyl ammonium chloride. Supplement in support of MRID#
411055-01. Performed by ABC Laboratories, Inc., Columbia, Missouri.
Submitted by ADBAC Joint Venture/Chemical Specialties Manufacturers
Association, Washington, DC.

424152-01 Carpenter, M. and M. Fennessey. 1992. Determination of the
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> ADBAC in pH 7 buffered solution at 25° C. Supplement in support of
> MRID# 408356-03. Performed by ABC Laboratories, Inc., Columbia,
> Missouri. Submitted by ADBAC Joint Venture/Chemical Specialties
> Manufacturers Association, Washington, DC.
>
> Dobbs, M.G., Cherry, D.S., Scott, J.C., Petrille, J.C. 1995.
> Environmental Assessment of an Alkyl Dimethyl Benzyl Ammonium Chloride
> (ADBAC) Based Molluscicide Using Laboratory Tests. Virginia Tech
> University Center for Environmental and Hazardous Materials Studies
> Blacksburg, VA
>
> Environmental Fate and Groundwater Branch (EFGB). 1993. EFGB review of
> alkyl dimethyl benzyl ammonium chloride. Memo from E. Regelman, EFGB,
> to J. Lee, Antimicrobial Program Branch.
>
> Lee, C. 1992. Assessment of the Biodegradability of ADBAC and DDAC.
> Unpublished report prepared by Roy F. Weston, Inc. Contractor's Fate
> Summary Review. Document Image No. 2011644.