![](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

> February 27, 2006

**[MEMORANDUM]{.underline}**

**SUBJECT:** Environmental Effects Assessment of Didecyl dimethyl
ammonium chloride (DDAC) for the Reregistration Eligibility Decision
(RED) Document

> **Case No.**: 3003 **DP Barcode:** 323305

**FROM:** David C. Bays, Microbiologist

Risk Assessment and Science Support Branch (RASSB)

Antimicrobials Division (7510C)

**TO:** Mark Hartman, Branch Chief

Ben Chamblis, Acting Team Leader

Najm Shamim, Risk Assessor

Regulatory Management Branch II

Antimicrobials Division (7510C)

Tracy Lantz, Chemical Review Manager

Regulatory Management Branch I

> Antimicrobials Division (7510C)

**THRU:** Rick Petrie, Acting Team Leader, Team Three

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}**

Didecyl dimethyl ammonium chloride 069149 7173-51-5 DDAC

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

**ECOLOGICAL HAZARD AND ENVIRONMENTAL**

**RISK ASSESSMENT CHAPTER**

**Didecyl Dimethyl Ammonium Chloride (DDAC)**

**PC Code 069149**

**CASE No.: 3003**

**02/02/2006**

**David C. Bays**

**Antimicrobials Division**

**Office of Pesticide Programs**

**U.S. Environmental Protection Agency**

**1200 Pennsylvania Avenue, NW**

**Washington, DC 20460**

Table of Contents

I. Summary of
Uses....................................................................................3

II\. Ecological Toxicity Data . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

A.  Toxicity to Terrestrial Animals . . . . . . . . . . . . . . . . . .
    . . . . . . . . . . . . . . . . . . . . 4

> 1\. Birds, Acute and Subacute
> ...........................................................4
>
> 2\. Mammals, Acute and Chronic . . . . . . . . . . . . . . . . . . . .
> . . . . . . . . . . . . . . . . 5

B. Toxicity to Aquatic Animals
.............................................................6

1\. Freshwater Fish, Acute . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . 6

2\. Freshwater Fish, Chronic
........................................................8

3\. Freshwater Invertebrates,
Acute..............................................\...8

4\. Freshwater Invertebrates, Chronic
.............................................9

5\. Estuarine and Marine Organisms
...............................................10

C. Toxicity to Plants . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . .10

III\. Risk Assessment and Risk Characterization . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . 11

A. Environmental Fate Assessment Summary . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . 13

B. Environmental Exposure Assessment
..................................................14

C. Endangered Species Considerations . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . 26

III\. Confirmatory Data Required. . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . .. . . . . . 27

IV\. Label Hazard Statements for Terrestrial and Aquatic Organisms. . .
. . . . . . . . . . . . . . 27

V. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

**I. Summary of Uses**

DDAC includes structurally similar quaternary ammonium compounds (quats)
that are characterized by having a positively charged nitrogen atom
covalently bonded to two alkyl groups (one at least eight carbons in
length) and two methyl groups. These chemicals are highly water soluble
and have a wide variety of uses and formulations. The following is a
list of the general uses of these chemicals:

# CURRENT USES

Algicide/Algistat

Bactericide/Bacteriostat

Fungicide/Fungistat

Insecticide -- termiticide (wood preservative)

Disinfectant

Microbiocide/Microbiostat

Miticide

Mold and mildew control

Molluscicide

Sanitizer (food and non-food contact hard surface)

Slimicide

Tuberculocide

Virucide

The specific uses include Agricultural, Agricultural Premises and
Equipment (hatchery rooms, incubators, mushroom farms, animal housing
facilities, citrus farms, swine/turkey poultry farms, flower shops,
greenhouses), Industrial processes and water systems (oil fields,
cooling water) Swimming Pools, Aquatic areas (decorative pools and
fountains, ponds, water displays, standing water, greenhouse/nurseries),
Wood treatment, Residential and Public Access Premises (homes, mobile
homes, cars, campgrounds, trailer campers, boats, playgrounds, public
facilities, trucks), Medical Premises and Equipment (hospitals, health
care facilities, medical/dental offices, nursing homes, operating rooms,
patient care facilities, clinics, isolation wards, medical research
facilities, autopsy rooms, ICU areas, recovery anesthesia, emergency
rooms, X-ray cat labs, newborn nurseries, orthopedics, respiratory
therapy, acute care institutions, alternate care institutions,
healthcare institutions, funeral homes, mortuaries, day-care
facilities), Commercial, Institutional and Industrial Premises and
Equipment (athletic/recreational facilities, exercise facilities,
schools, colleges, dressing rooms, transportation terminals, locker
rooms, motels, hotels, barber and beauty salons, health clubs, emergency
vehicles, correctional facilities, factories, commercial florists,
dorms, convenience stores, recreational centers, offices, commercial and
institutional laundry mats, industrial premise), Food Handling/Storage
Establishments Premises and Equipment (Disinfectant) ( restaurants, food
service establishments, food processing plans/facilities, bottling and
beverage processing plans, bars, cafeterias, supermarkets, dairies, egg
processing plants, federally inspected meat and poultry plants, food
handling areas, food preparation areas, food storage areas,
institutional kitchens, USDA inspected food processing facilities,
breweries, fast food operations, tobacco, rendering plants,
fishery/milk/citrus/wine/ice cream/potato processing plants, school
lunchrooms), and Clean/Deodorization (water/smoke restoration, sewer
backup/river flood cleanup, garbage storage areas, pet areas, garbage
bins and cans)

The following are the current formulation types for these chemicals:

Soluble concentrate

Ready to use solution

Pressurized liquid

Water soluble packaging

Formulation intermediate

Wettable powder

Impregnated materials

Emulsifiable concentrate

II. **Ecological Toxicity Data**

> **A. Toxicity to Terrestrial Animals**

**1. Birds, Acute and Subacute**

For indoor uses, an acute oral toxicity study using the technical grade
of the active ingredient (TGAI) is required to establish the toxicity of
these chemicals to birds. The preferred test species is either mallard
duck (a waterfowl) or northern bobwhite quail Ian upland game bird).
Several avian acute toxicity studies were found in the Agency's files
for this chemical. **Avian acute oral toxicity testing (850.2100/71-1),
preferably using the bobwhite quail, is required to support the
currently registered uses of these chemicals.**

Avian dietary toxicity studies using the TGAI of these chemicals are not
required for indoor uses.

The results from the avian acute toxicity and dietary studies obtained
from the Agency's files are summarized in the table below (Table 1).

Table 1

+-------------+-------------+-------------+-------------+-------------+
| Test and    | Results     | Toxicity    | Comments    | Reference   |
| Organism    | LC~50~      | Category    |             |             |
|             | (mg/L) or   |             |             |             |
|             | LD~50~      |             |             |             |
|             | (mg/kg)     |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Avian       | 239         | Practically | Core study  | Long et al. |
| dietary     |             | non-toxic   |             | 1991a       |
| LC~50~      | NOEC        |             |             |             |
| Bobwhite    | **\<**31    |             |             | MRID# -     |
| Quail       |             |             |             | 41785801    |
| (*Colinus   |             |             |             |             |
| vi          |             |             |             |             |
| rginianus*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Avian       | \>5620      | Practically | Core study  | Long et al. |
| dietary     |             | non-toxic   |             | 1991b       |
| LC~50~      | NOEC = 562  |             |             |             |
| Mallard     |             |             |             | MRID# -     |
| Duck (*Anas |             |             |             | 41785802    |
| pla         |             |             |             |             |
| tyrhynchos* |             |             |             |             |
| ~)~         |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Avian       | 217         | Moderately  | Core Study  | Campbell et |
| single dose |             | toxic       |             | al. 1991    |
| oral LD~50~ |             |             |             |             |
| Bobwhite    |             |             |             | MRID# -     |
| Quail       |             |             |             | 41785803    |
| (Co*linus   |             |             |             |             |
| vi          |             |             |             |             |
| rginianus*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Eight day   | \>5000      | Practically | S           | Henck, H.W. |
| dietary     |             | non-toxic   | upplemental | 1986        |
| LC~50~      |             |             | Study       |             |
| Bobwhite    |             |             |             | ACC# -      |
| Quail       |             |             |             | 40129801    |
| (*Colinus   |             |             |             |             |
| vi          |             |             |             |             |
| rginianus*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 8-day       | \>5620      | Practically | Core Study  | Fink, R.    |
| dietary     |             | non-toxic   |             | and Beavers |
| LC~50~      |             |             |             | J. 1985     |
| Mallard     |             |             |             |             |
| Duck (A*nas |             |             |             | ACC# -      |
| plat        |             |             |             | 258798      |
| yrhynchos*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 8-day       | \>5620      | Practically | Core Study  | Fink, R.    |
| dietary     |             | non-toxic   |             | and         |
| LC~50~      |             |             |             | Beavers, J. |
| Bobwhite    |             |             |             | 1982        |
| Quail       |             |             |             |             |
| (*Colinus   |             |             |             | ACC# -      |
| vi          |             |             |             | 258798      |
| rginianus*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Acute Oral  | 54.4        | Moderately  | Core Study  | Fink, R.    |
| LD~50~      |             | toxic       |             | and         |
| Bobwhite    |             |             |             | Beavers, J. |
| Quail       |             |             |             | 1985        |
| (*Colinus   |             |             |             |             |
| vi          |             |             |             | ACC# -      |
| rginianus*) |             |             |             | 258798      |
+-------------+-------------+-------------+-------------+-------------+
| 8-day       | 1950        | None given  | S           | Cannon Lab. |
| dietary     | [+]{        |             | upplemental | 1973        |
| LC~50~      | .underline} |             | Study       |             |
| Bobwhite    | 236.6       |             |             | ACC# -      |
| Quail       |             |             |             | 132164      |
| (*Colinus   |             |             |             |             |
| vi          |             |             |             |             |
| rginianus*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 8-day       | \>3500      | None given  | S           | Cannon Lab. |
| dietary     |             |             | upplemental | 1973        |
| LC~50~      |             |             | Study       |             |
| Mallard     |             |             |             | ACC# -      |
| Duck (*Anas |             |             |             | 132164      |
| plat        |             |             |             |             |
| yrhynchos*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Acute Oral  | 0.33 gm/kg  | None given  | S           | Cannon Lab. |
| Toxicity    |             |             | upplemental | 1977        |
| LD~50~      |             |             | Study       |             |
| Mallard     |             |             |             | ACC# -      |
| Duck (*Anas |             |             |             | 225889      |
| plat        |             |             |             |             |
| yrhynchos*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

The results of the dietary avian studies indicate that DDAC is
practically non-toxic to both mallard duck and bobwhite quail. In the
Acute oral studies, the chemical was found to be moderately toxic to
bobwhite quail. All of these studies were considered to be core and met
guideline requirements at the time they were submitted to the Agency.

**2. Mammals**

A summary of mammalian toxicity of DDAC is presented in the "Evaluation
of Toxicity Database for Reregistration Eligibility Decision Document
Disciplinary Chapter".

> **B. Toxicity to Aquatic Animals**

**1. Freshwater Fish, Acute**

Freshwater fish toxicity studies using the TGAI are required to
establish the toxicity of these chemicals to fish. Data are generally
required for only one species. Testing in two fish species is required
for stable chemicals with high volume effluents (e.g., including, but
not limited to, egg washing, fruit and vegetable rinses, swimming pools
or materials preservatives) and if the LC~50~ in the first species is
greater than (\>) 1 ppm. The preferred test species are rainbow trout (a
coldwater fish) and bluegill sunfish (a warmwater fish), although other
test species identified in the OPPTS Guideline (i.e., OPPTS 850.1075
(e)(4)(i)(A)) may also be used. Several freshwater fish acute toxicity
studies were identified from peer-reviewed literature (Table 2). Several
freshwater fish acute toxicity studies were found in the Agency's files
(Table 3). **Freshwater fish acute toxicity testing (850.1075/72-1) on
one species, preferably the rainbow trout, is required to support the
currently registered uses of this chemical.**

The results from freshwater fish acute toxicity studies obtained from
peer-reviewed literature are summarized in the table below (Table 2).

# Table 2

+-----------------+-----------------+-----------------+-----------------+
| Organism        | Results         | Comments        | Reference       |
+-----------------+-----------------+-----------------+-----------------+
| White Sturgeon  | Larvae: 24-h    | 8 day old       | Bennett, W.R.   |
| (*Acipenser     | LC~50~ = 0.74   | larvae          | and Farrell,    |
| transmontanus*) | ppb (0.1, 1.0); |                 | A.P. 1998.      |
|                 | 100% mortality  | 42 day old fry  |                 |
|                 | at \>1.0 ppb;   |                 | Water Qual.     |
|                 | NOEC = 0.5 ppb  | 96 hour test    | Res. J. Can.    |
|                 |                 | duration        | 33(1)95-110.    |
|                 | Fry: 100%       |                 |                 |
|                 | mortality at    | no mortality in |                 |
|                 | 10.0 ppb        | control groups  |                 |
+-----------------+-----------------+-----------------+-----------------+
| Rainbow Trout   | 96-h LC~50~ =   | 96 hour test    | Wood, A.W. et.  |
| (*Oncorhynchus  | 0.409 mgL^-1^   | duration        | al. 1996. Can.  |
| mykiss*)        |                 |                 | J. Fish. Aquat. |
|                 |                 | flow-through    | Sci.            |
|                 |                 | system          | 53:2424-2432.   |
+-----------------+-----------------+-----------------+-----------------+
| Japanese Makata | IC~25~ = 439.7  | 9 day test for  | Tatarazako, N.  |
| (*Oryzias*      | [+]{.underline} | zebrafish       | et al. 2002.    |
| latipes) and    | 9.9 ug/l (NOEC  |                 | Health Sci.     |
| Zebrafish       | = 312.5 ug/l)   | 14 day test for | 48(4):359-365.  |
| (*Danio rerio*) | for zebrafish;  | makata          |                 |
|                 |                 |                 |                 |
|                 | IC~25~ = 1563   |                 |                 |
|                 | [+]{.underline} |                 |                 |
|                 | 14.5 ug/l (NOEC |                 |                 |
|                 | = 1250 ug/l)    |                 |                 |
|                 | for makata      |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| White Sturgeon  | LC~50~ = 10 to  | 96-hr. static   | Teh, S.J. et    |
| (*Acipenser     | 50 ug/l for 3   | renewal method  | al. 2003.       |
| transmontanus*) | day, 58.5 ug/l  | using 3, 11, 42 | Toxicol. Chem.  |
|                 | for 11 day,     | day larvae, and | 2               |
|                 | 99.7 ug/l for   |                 | 2(9):2152-2158. |
|                 | 42 day old      | 78 day old      |                 |
|                 | larvae; LC~50~  | juveniles       |                 |
|                 | = 100 to 250    |                 |                 |
|                 | ug/l for 78 day |                 |                 |
|                 | old juveniles   |                 |                 |
+-----------------+-----------------+-----------------+-----------------+
| Rainbow Trout   | LC~50~ = 537    | 96-hr. test     | Bailey, H.C. et |
| (*Orcorhynchus  | ug/l            | using juvenile  | al. 1999. Water |
| mykiss*)        |                 | rainbow trout   | Res.            |
|                 |                 |                 | 33              |
|                 |                 |                 | (10):2410-2414. |
+-----------------+-----------------+-----------------+-----------------+

The results from the above fish acute toxicity studies obtained from the
literature indicate that DDAC is toxic to fish at microgram
concentrations. The chemical would be considered to be very highly toxic
to fish. However these studies do not meet current guideline
requirements.

The results from freshwater fish acute toxicity studies obtained from
the Agency's files are summarized in the table below (Table 3).

**Table 3**

+-------------+-------------+-------------+-------------+-------------+
| Test and    | Results     | Toxicity    | Comments    | Reference   |
| Organism    | LC~50~      | Category    |             |             |
|             | (mg/L)      |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Acute       | 478         | Practically | S           | Rhodes,     |
| Toxicity    |             | non-toxic   | upplemental | R.E. 2000a  |
| LC~50~      |             |             | Study       |             |
| Rainbow     |             |             |             | MRID# -     |
| Trout       |             |             |             | 41592002    |
| (*O         |             |             |             |             |
| nchorynchus |             |             |             |             |
| mykiss*)    |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Acute       | 188         | Practically | S           | Rhodes,     |
| Toxicity    |             | non-toxic   | upplemental | R.E. 2000b  |
| LC~50~      |             |             | Study       |             |
| Bluegill    |             |             |             | MRID# -     |
| Sunfish     |             |             |             | 45192001    |
| (*Lepomis   |             |             |             |             |
| ma          |             |             |             |             |
| crochirus*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Static      | 0.96        | Highly      | Core Study  | Collins,    |
| Acute       |             | toxic       |             | M.K. 1994   |
| Toxicity    |             |             |             |             |
| LC~50~      |             |             |             | MRID# -     |
| Sheepshead  |             |             |             | 43620001    |
| minnow      |             |             |             |             |
| (*Cyprindon |             |             |             |             |
| v           |             |             |             |             |
| ariegates*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Static      | 0.32        | Highly      | Core Study  | LeLievre,   |
| Acute       |             | toxic       |             | M.K. 1990a  |
| Toxicity    |             |             |             |             |
| LC~50~      |             |             |             | MRID# -     |
| Bluegill    |             |             |             | 41578001    |
| Sunfish     |             |             |             |             |
| (*Lepomis   |             |             |             |             |
| ma          |             |             |             |             |
| crochirus*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Static      | 1.0         | Highly      | Core Study  | LeLievre,   |
| Acute       |             | toxic       |             | M.K. 1990b  |
| Toxicity    |             |             |             |             |
| LC~50~ Coho |             |             |             | MRID# -     |
| Salmon      |             |             |             | 41578003    |
| (*O         |             |             |             |             |
| ncorhynchus |             |             |             |             |
| kisutch*)   |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Acute       | 0.5         | Highly      | Core Study  | Onyx        |
| Toxicity    |             | toxic       |             | Chemical    |
| 96-hr       |             |             |             | Co. 1982a   |
| LC~50~ Blue |             |             |             |             |
| gill        |             |             |             | PROJ# -     |
| sunfish     |             |             |             | 038901      |
| (*Lepomis   |             |             |             |             |
| ma          |             |             |             |             |
| crochirus*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Acute       | 2.8         | Moderately  | Core Study  | Onyx        |
| Toxicity    |             | toxic       |             | Chemical    |
| 96-hr       |             |             |             | Co. 1982b   |
| LC~50~      |             |             |             |             |
| Rainbow     |             |             |             | PROJ# -     |
| Trout       |             |             |             | 038901      |
| (*O         |             |             |             |             |
| ncorhynchus |             |             |             |             |
| mykiss)*    |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Acute       | 1.6         | Moderately  | Core Study  | Surpremant, |
| Toxicity    |             | toxic       |             | D.C. 1986   |
| 96-hr       |             |             |             |             |
| LC~50~      |             |             |             | ACC# -      |
| Rainbow     |             |             |             | 40129801    |
| Trout       |             |             |             |             |
| (*O         |             |             |             |             |
| ncorhynchus |             |             |             |             |
| mykiss*)    |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 96 hr.      | 0.27        | Not given   | S           | Wells Labs  |
| Static      |             |             | upplemental | 1971a       |
| Bioassay    |             |             |             |             |
| LC~50~      |             |             |             | ACC# -      |
| Bluegill    |             |             |             | 007958      |
| Sunfish     |             |             |             |             |
| (*Lepomis   |             |             |             |             |
| ma          |             |             |             |             |
| crochirus*) |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 96 hr.      | 1.1         | Not given   | S           | Wells Labs  |
| Static      |             |             | upplemental | 1971b       |
| Bioassay    |             |             |             |             |
| LC~50~      |             |             |             | ACC# -      |
| Rainbow     |             |             |             | 007958      |
| Trout       |             |             |             |             |
| (*O         |             |             |             |             |
| ncorhynchus |             |             |             |             |
| mykiss*)    |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

As shown in Table 3, the toxicity ranged from 0.27 to 478 mg/L, which
ranged in toxicity category from practically nontoxic to moderately
toxic to highly toxic, depending on the product being tested.

**2. Freshwater Fish, Chronic**

Fish early life stage testing is not required for the currently
registered indoor uses of this chemical.

**3. Freshwater Invertebrates, Acute**

A freshwater aquatic invertebrate toxicity test using the TGAI is
required to establish the toxicity of a pesticide to aquatic
invertebrates. The preferred test species is *Daphnia magna* or *Daphnia
pulex.* Several studies testing these organisms were found in the
Agencies files (Table 4). **Freshwater invertebrate acute toxicity
testing (850.1010/72-2) is required for the currently registered uses of
this chemical.**

# Table 4

+-------------+-------------+-------------+-------------+-------------+
| Test and    | Results     | Toxicity    | Comments    | Reference   |
| Organism    |             | Category    |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Freshwater  | 48-hr. EC   | Very highly | Core Study  | LeLievre,   |
| i           | ~50~ = 94   | toxic       |             | M.K. 1990c  |
| nvertebrate | ug/l        |             |             |             |
| static      |             |             |             | MRID# -     |
| acute       |             |             |             | 41578002    |
| toxicity    |             |             |             |             |
| *Daphnia    |             |             |             |             |
| magna*      |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Freshwater  | 48-hr.      | Very highly | Core Study  | Onyx        |
| I           | LC~50~ =    | toxic       |             | Chemical    |
| nvertebrate | 0.018 mg/l  |             |             | Co. 1982c   |
| Static      |             |             |             |             |
| Acute       |             |             |             | PROJ# -     |
| Toxicity    |             |             |             | 038901      |
| *Daphnia    |             |             |             |             |
| magna*      |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Acute       | 48-hr.      | Very highly | Core Study  | Surprenant, |
| Toxicity    | LC~50~ =    | toxic       |             | E.C. 1987   |
| *Daphnia    | 0.052 mg/l  |             |             |             |
| pulex*      |             |             |             | ACC# -      |
|             |             |             |             | 40129801,   |
|             |             |             |             | 02, 03      |
+-------------+-------------+-------------+-------------+-------------+
| Static      | 48-hr.      | None given  | S           | Roberts, S. |
| 48-hr.      | LC~50~ =    |             | upplemental | 1977        |
| toxicity    | 0.095 mg/l  |             | Study       |             |
| study       |             |             |             | No. -       |
| *Daphnia    |             |             |             | 7E-6686     |
| magna*      |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 48-hr.      | 48-hr.      | None given  | S           | Cannon Labs |
| Static      | LC~50~ =    |             | upplemental | 1976        |
| aquatic     | 0.1 mg/l    |             | Study       |             |
| i           |             |             |             | ACC# -      |
| nvertebrate |             |             |             | 225596      |
| study       |             |             |             |             |
| *Daphnia    |             |             |             |             |
| magna*      |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

As shown in Table 4, this chemical is very highly toxic to aquatic
invertebrates.

One study was found in the open literature and is summarized in Table 5.

# Table 5

+-----------------+-----------------+-----------------+-----------------+
| Organism        | Results         | Comments        | Reference       |
+-----------------+-----------------+-----------------+-----------------+
| ## Daphna magna | IC~25~ = 211.2  | 21 day test     | Tatarazako, N.  |
|                 | [+]{.underline} |                 | et al. 2002.    |
|                 | 6.8 ug/l (NOEC  |                 | Health Sci.     |
|                 | = 125 ug/l)     |                 | 48(4):359-365.  |
+-----------------+-----------------+-----------------+-----------------+

The Daphnid study in Table 5 indicates that DDAC is very highly toxic to
*Daphnia magna*.

**4. Freshwater Invertebrates, Chronic**

Chronic aquatic invertebrate testing is conditionally required for the
currently registered wood preservative use of this chemical. One study
was found in the Agency's files (Table 6).

# Table 6

+-------------+-------------+-------------+-------------+-------------+
| Test and    | Results     | Toxicity    | Comments    | Reference   |
| Organism    |             | Category    |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Whole       | LC~50~ =    | None given  | S           | England,    |
| Sediment    | \>1000 (mg  |             | upplemental | D.C. and    |
| chronic     | ai/kg dry   |             | Study       | Leak, T.    |
| toxicity    | sediment)   |             |             | 1995        |
| i           |             |             |             |             |
| nvertebrate | EC~50~ =    |             |             | MRID# -     |
| test Midge  | 1981        |             |             | 45821701    |
| (           |             |             |             |             |
| *Chironomus |             |             |             |             |
| tentans*)   |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

The results of the above study indicate that DDAC is practically
non-toxic to the Midge in a whole sediment chronic toxicity test. The
test was considered Supplemental.

**5. Estuarine and Marine Organisms**

Acute toxicity testing with estuarine and marine organisms using the
TGAI is conditionally required for the wood preservative uses of this
chemical. Several studies on marine/estuarine invertebrates were found
in the Agency's files (Table 7).

# Table 7

+-------------+-------------+-------------+-------------+-------------+
| Test and    | Results     | Toxicity    | Comments    | Reference   |
| Organism    |             | Category    |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Estuarine   | 96-hr.      | Very highly | Core Study  | LeLievre,   |
| I           | LC~50~ = 69 | toxic       |             | M. K. 1990d |
| nvertebrate | ug/l        |             |             |             |
| Static      |             |             |             | MRID# -     |
| Acute       |             |             |             | 41578004    |
| Toxicity    |             |             |             |             |
| Mysid       |             |             |             |             |
| Shrimp      |             |             |             |             |
| (           |             |             |             |             |
| *Mysidopsis |             |             |             |             |
| bahia*)     |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 48-hr.      | Eggs: 9-hr. | None given  | Core Study  | Cannon Labs |
| EC~50~ and  |             |             |             | 1974a       |
| 96-hr.      | EC~50~ = 19 |             |             |             |
| LC~50~      | ppm         |             |             | ACC# -      |
| oyster eggs |             |             |             | 249002      |
| and         | Larvae:     |             |             |             |
| str         | 48-hr.      |             |             |             |
| aight-hinge | LC~50~ =    |             |             |             |
| larvae      | 10.5 ppm;   |             |             |             |
|             | 96-hr.      |             |             |             |
|             | LC~50~ =    |             |             |             |
|             | 6.4 ppm     |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 96-hr.      | 96-hr.      | None given  | Core Study  | Cannon Labs |
| LC~50~      | LC~50~ =    |             |             | 1974b       |
| marine blue | 2.10        |             |             |             |
| crab        | [+]{        |             |             | ACC# -      |
|             | .underline} |             |             | 249002      |
|             | 1.28 ppm    |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 96-hr.      | 96-hr.      | None given  | Core Study  | Cannon Labs |
| LC~50~      | LC~50~ =    |             |             | 1974c       |
| marine      | 2.78        |             |             |             |
| grass       | [+]{        |             |             | ACC \# -    |
| shrimp      | .underline} |             |             | 249002      |
|             | 0.29        |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

As shown in Table 6, this chemical is very highly toxic to mysid shrimp,
practically non-toxic to oyster eggs and straight-hinge larvae, and
moderately toxic to blue crab and grass shrimp. Since all the studies
except the mysid shrimp are old, over 30 years, the results of the mysid
shrimp test would be the most reliable.

C.  **Toxicity** **to Plants**

Terrestrial and aquatic plant testing is required for the registered
wood preservative use of this chemical.

There were not aquatic phytotoxicity endpoints reported in the ECOTOX
data base (EPA, 2002). Two Alga toxicity studies on this chemical were
found in the Agency's files (Table 8).

# Table 8

+-------------+-------------+-------------+-------------+-------------+
| Test and    | Results     | Toxicity    | Comments    | Reference   |
| Organism    |             | Category    |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 96-hr.      | EC~10~ =    | None given  | S           | Krueger,    |
| Toxicity    | 9.64 ug     |             | upplemental | H.O. et al. |
| Test        | ai/L        |             | Study       | 2003        |
| Freshwater  |             |             |             |             |
| Alga        | EC~50~ =    |             |             | MRID# -     |
| (*          | 73.2 ug     |             |             | 45896401    |
| Selenastrum | ai/L        |             |             |             |
| capr        |             |             |             |             |
| icornutum*) | NOEC = 27   |             |             |             |
|             | ug ai/L     |             |             |             |
| Using       |             |             |             |             |
| Natural     |             |             |             |             |
| Surface     |             |             |             |             |
| Water       |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| 96-hr       | 96-hr       | None given  | Core Study  | Krueger,    |
| Toxicity    | EC~10~ =    |             |             | H.O. et al. |
| Test with   | 6.56 ug/L   |             |             | 2002        |
| Freshwater  |             |             |             |             |
| Alga        | EC~50~ =    |             |             | MRID# -     |
| (*          | 14.22 ug/L  |             |             | 48596402    |
| Selenastrum |             |             |             |             |
| capr        | NOEC = 8    |             |             |             |
| icornutum*) | ug/L        |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

As shown in Table 8, DDAC was toxic to freshwater alga at microgram
concentrations.

One study was found in the open literature and is summarized in Table 9.

# Table 9

  ----------------- ----------------- ----------------- -----------------
  Organism          Results           Comments          Reference

  Green alga        IC~25~ = 10       72-hr test        Tatarazako, N.
  (*Selenastrum     [+]{.underline}                     2002 Health Sci.
  capricornutum*)   24.4 ug/l (NOEC =                   48(4): 359-365.
                    25 ug/l)                            
  ----------------- ----------------- ----------------- -----------------

The above study indicates that DDAC is toxic to green alga at microgram
concentrations.

**III. Risk Assessment and Characterization**

Risk assessment integrates the results of the exposure and ecotoxicity
data to evaluate the likelihood of adverse ecological effects. Also
playing a role is the environmental fate of a chemical. The following
sections present a summary of the environmental fate of DDAC and an
environmental exposure and ecological risk assessment. One method of
integrating the results of exposure and ecotoxicity data is called the
quotient method. For this method, risk quotients (RQs) are calculated by
dividing exposure estimates by ecotoxicity values, both acute and
chronic:

RQ = EXPOSURE/TOXICITY

RQs are then compared to OPP\'s levels of concern (LOCs). These LOCs are
criteria used by OPP to indicate potential risk to nontarget organisms
and the need to consider regulatory action. The criteria indicate that a
pesticide used as directed has the potential to cause adverse effects on
nontarget organisms. LOCs currently address the following risk
presumption categories: (1) **acute high** - potential for acute risk is
high, and regulatory action may be warranted in addition to restricted
use classification; (2) **acute restricted use** - the potential for
acute risk is high, but this may be mitigated through restricted use
classification; (3) **acute endangered species** - the potential for
acute risk to endangered species is high, and regulatory action may be
warranted; and (4) **chronic risk** - the potential for chronic risk is
high, and regulatory action may be warranted. Currently, AD does not
perform assessments for chronic risk to plants, acute or chronic risks
to nontarget insects, or chronic risk from granular/bait formulations to
mammalian or avian species.

The ecotoxicity test values (i.e., measurement endpoints) used in the
acute and chronic risk quotients are derived from the results of
required studies. Examples of ecotoxicity values derived from the
results of short-term laboratory studies that assess acute effects are:
(1) LC~50~ (fish and birds) (2) LD~50~ (birds and mammals) (3) EC~50~
(aquatic plants and aquatic invertebrates) and (4) EC~25~ (terrestrial
plants). Examples of toxicity test effect levels derived from the
results of long-term laboratory studies that assess chronic effects are:
(1) LOEC (birds, fish, and aquatic invertebrates) (2) NOEC (birds, fish
and aquatic invertebrates) and (3) MATC (Maximum Allowable Toxic
Concentration) (fish and aquatic invertebrates). For birds and mammals,
the NOEC value is used as the ecotoxicity test value in assessing
chronic effects. Other values may be used when justified. Generally, the
MATC (defined as the geometric mean of the NOEC and LOEC) is used as the
ecotoxicity test value in assessing chronic effects to fish and aquatic
invertebrates. However, the NOEC is used if the measurement endpoint is
production of offspring or survival.

Risk presumptions, along with the corresponding RQs and LOCs are
tabulated below.

  -----------------------------------------------------------------------
  **Risk Presumptions for Terrestrial Animals**
  -----------------------------------------------------------------------

  -----------------------------------------------------------------------

  ------------------------------------------------------------------------
  Risk Presumption         RQ                                    LOC
  ------------------------ ------------------------------------- ---------

  ------------------------------------------------------------------------

  -----------------------------------------------------------------------
  **Birds and Wild Mammals**

  -----------------------------------------------------------------------

  ------------------------ ------------------------------------- ---------
  Acute High Risk          EEC^1^/LC~50~ or LD~50~/sqft^2^ or    0.5
                           LD~50~/day^3^                         

  Acute Restricted Use     EEC/LC~50~ or LD~50~/sqft or          0.2
                           LD~50~/day (or LD~50~ \< 50 mg/kg)    

  Acute Endangered Species EEC/LC~50~ or LD~50~/sqft or          0.1
                           LD~50~/day                            

  Chronic Risk             EEC/NOEC                              1
  ------------------------ ------------------------------------- ---------

^1^ abbreviation for Estimated Environmental Concentration (ppm) on
avian/mammalian food items

^2^ [mg/ft^2^]{.underline} ^3^ [mg of toxicant consumed/day]{.underline}

LD~50~ \* wt. of bird LD~50~ \* wt. of bird

  -----------------------------------------------------------------------
  **Risk Presumptions for Aquatic Animals**

  -----------------------------------------------------------------------

  ------------------------------- ------------------------------ --------
  Risk Presumption                RQ                             LOC

  Acute High Risk                 EEC^1^/LC~50~ or EC~50~        0.5

  Acute Restricted Use            EEC/LC~50~ or EC~50~           0.1

  Acute Endangered Species        EEC/LC~50~ or EC~50~           0.05

  Chronic Risk                    EEC/MATC or NOEC               1
  ------------------------------- ------------------------------ --------

^1^ EEC = (ppm or ppb) in water

  ------------------------------- ------------------------------ --------
  **Risk Presumptions for                                        
  Plants**                                                       

  Risk Presumption                RQ                             LOC
  ------------------------------- ------------------------------ --------

+-----------------------------------------------------------------------+
| ## Terrestrial and Semi-Aquatic Plants                                |
+-----------------------------------------------------------------------+

  ------------------------------- ------------------------------ --------
  Acute High Risk                 EEC^1^/EC~25~                  1

  Acute Endangered Species        EEC/EC~05~ or NOEC             1
  ------------------------------- ------------------------------ --------

+-----------------------------------------------------------------------+
| ## Aquatic Plants                                                     |
+-----------------------------------------------------------------------+

  ------------------------------- ------------------------------ --------
  Acute High Risk                 EEC^2^/EC~50~                  1

  Acute Endangered Species        EEC/EC~05~ or NOEC             1
  ------------------------------- ------------------------------ --------

^1^ EEC = lbs ai/A

^2^ EEC = (ppb/ppm) in water

> **A. Environmental Fate Assessment Summary (excerpted from the
> Environmental Fate Science Chapter of this RED document)**

The Agency has reviewed various environmental fate studies and reports
submitted for DDAC. The data indicate that DDAC is hydrolytically and
photolytically stable under abiotic and buffered conditions. Aquatic
metabolism studies indicate that DDAC is also stable to microbial
degradation. However, a report on the biodegradability of DDAC concluded
that the degree of DDAC 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. Accordingly, DDAC is considered biodegradable under aerobic
and anaerobic conditions and, therefore, environmentally acceptable. In
addition, DDAC is immobile in soil because of its strong tendency to
bind to sediment/soil. Bioaccumulation of DDAC in terrestrial or aquatic
organisms is not likely to occur. Further information on the
environmental fate of DDAC may be found in the Environmental Fate
Chapter of this RED document.

> **B. Environmental Exposure and Ecological Risk Assessment**

Freshwater and estuarine/marine aquatic organisms, and plants could
potentially be exposed to DDAC discharged into the aquatic environment.
The Agency conducted modeling in 2005 to estimate the exposure and
environment risk resulting from such discharges of DDAC from the
once-through cooling tower and antisapstain wood treatment uses.

(1) **Tier I 2005 Probabilistic Dilution Modeling for once-through
    cooling tower use**

> The EPA Office of Water PDM4 Model was used to estimate exposure from
> once-through cooling tower use as a preliminary screen in the absence
> of field residue data. Once-through cooling water systems applying a
> continuous dose of pesticide located on low-flow streams (100 million
> gallons per day) were used as the scenarios providing the maximum
> concentrations of DDAC in the receiving water, e.g., the "worst case"
> scenarios. It was assumed that the chemical was being applied at the
> highest listed maintenance rate shown on any of the DDAC product
> labels. Actual probabilities of exceedance of concentrations in
> receiving waters are likely lower than what are shown in Table 10 due
> to higher flow rates and possible degradation/ dissipation of
> available DDAC by mechanisms other than hydrolysis. A summary of
> concentrations over time is provided in Table 10. The concentrations
> selected for analysis were the measured endpoints derived from the
> results of the required studies (see Section I.B.)
>
> **Table 10 - Table of LOC\'s**

  ------------------ ----------- ----------- --------------- --------------
  Taxa               LC50/EC50   High Acute  Restricted Use  Endangered
                                 Risk LOC (X LOC (X 0.1)     Species LOC (X
                                 0.5)                        0.05)

  Freshwater fish-   **320 ppb** **160**     **32** **ppb**  **16 ppb**
  warm                           **ppb**                     

  Freshwater fish -- **1600      **800 ppb** **160 ppb**     **80 ppb**
  cold               ppb**                                   

  Freshwater         **94 ppb**  **47 ppb**  **9.4 ppb**     **4.7 ppb**
  invertebrate                                               

  Marine fish        **96 ppb**  **48 ppb**  **9.6 ppb**     **4.8 ppb**

  Marine mollusk     **No data**                             

  Marine             **69 ppb**  **34.5      **6.9 ppb**     **3.45 ppb**
  invertebrate                   ppb**                       

  Green alga         **14ppb**   **7ppb**    **1.4ppb**      **0.7ppb**

  Aquatic vascular   **No data**                             
  plant                                                      

  Freshwater fish    **No data**                             
  chronic                                                    
  ------------------ ----------- ----------- --------------- --------------

**Modeling Results for DDAC -- Once-through Cooling Use**

The following tables list the probability that levels of concern (LOCs)
will be exceeded for aquatic organisms. Various dosages, dosing methods
(continuous vs intermittent), and water flow rates (low, medium, high
stream flow rates) were modeled (Versar 2006).

Results are given as percent of days per year and number of days per
year of LOC exceedance for the different aquatic animal and plant
groups. **BOLD** indicates exceedance of LOC (e.g., if the number of
days exceeded is equivalent to or greater than number of days used to
determine the toxicology endpoint, risk is assumed). Dose rates selected
from labeling for this chemical were 32 and 63 ppm for continuous feed
and 1000 and 1800 ppm for intermittent feed.

Table 11. Average Exceedances, Low Continuous Dose

+---------------+-------------+------------------+--------------------+
| **Taxa        | **Endpoint  | **Levels of      |                    |
| (Duration of  | Value**     | Concern (ppb), % |                    |
| Acute Study,  |             | Days Exceeded,   |                    |
| in Days)**    | **(From     | \# Days/Year     |                    |
|               | Study,      | Exceeded**       |                    |
|               | ppb)**      |                  |                    |
+---------------+-------------+------------------+--------------------+
|               |             | **Acute          | **Endangered       |
|               |             | Nontarget**      | Species**          |
|               |             |                  |                    |
|               |             | **(LC~50~ or     | **(LC~50~ or       |
|               |             | EC~50~ \* 0.5)** | EC~50~ \* 0.05)**  |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Low Flow      |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 98.2%, 358       | 99.8%, 364 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 97.7%, 357       | 99.8%, 364 days**  |
| (Low-end) (2) |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 89.9%, 328       | 99.1%, 362 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 89.3%, 326       | 99.1%, 362 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 86.2%, 315       | 98.8%, 361 days**  |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 72.4%, 264       | 95.5%, 349 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 58.5%, 214       | 85.5%, 312 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Medium Flow   |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 99.7%, 364       | 100%, 365 days**   |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 99.6%, 364       | 100%, 365 days**   |
| (Low-end) (2) |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 97.8%, 357       | 99.9%, 364 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 97.6%, 356       | 99.8%, 364 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 96.7%, 353       | 99.8%, 364 days**  |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 89.5%, 327       | 99.3%, 362 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 76.5%, 279       | 96.5%, 352 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| High Flow     |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 98.6%, 360       | 100%, 365 days**   |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 98.4%, 359       | 100%, 365 days**   |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 97.6%, 356       | 100%, 365 days**   |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 89.2%, 326       | 99.9%, 365 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 77.5%, 283       | 97.4%, 355 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+

Table 12. Average Exceedances, High Continuous Dose

+---------------+-------------+------------------+--------------------+
| **Taxa        | **Endpoint  | **Levels of      |                    |
| (Duration of  | Value (From | Concern (ppb), % |                    |
| Acute Study,  | Study,      | Days Exceeded,   |                    |
| in Days)**    | ppb)**      | \# Days/Year     |                    |
|               |             | Exceeded**       |                    |
+---------------+-------------+------------------+--------------------+
|               |             | **Acute          | **Endangered       |
|               |             | Nontarget**      | Species**          |
|               |             |                  |                    |
|               |             | **(LC~50~ or     | **(LC~50~ or       |
|               |             | EC~50~ \* 0.5)** | EC~50~ \* 0.05)**  |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Low Flow      |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 99.6%, 363       | 100%, 365 days**   |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 99.4%, 363       | 99.9%, 365 days**  |
| (Low-end) (2) |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 95.1%, 347       | 99.8%, 364 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 94.7%, 346       | 99.8%, 364 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 92.5%, 338       | 99.7%, 364 days**  |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 80.4%, 293       | 98.8%, 360 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 66.7%, 243       | 92%, 336 days**    |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Medium Flow   |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 99.9%, 365       | 100%, 365 days**   |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 99.9%, 365       | 100%, 365 days**   |
| (Low-end) (2) |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 99.1%, 362       | 100%, 365 days**   |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 99%, 361 days**  | 99.9%, 365 days**  |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 98.6%, 360       | 99.9%, 365 days**  |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 94.3%, 344       | 99.8%, 364 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 84.8%, 310       | 98.5%, 360 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| High Flow     |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 99.7%, 364       | 100%, 365 days**   |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 99.7%, 364       | 100%, 365 days**   |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 99.5%, 363       | 100%, 365 days**   |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 94.9%, 346       | 100%, 365 days**   |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 84.1%, 307       | 99.4%, 363 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+

Table 13. Average Exceedances, Low Intermittent Dose

+---------------+-------------+------------------+--------------------+
| **Taxa        | **Endpoint  | **Levels of      |                    |
| (Duration of  | Value (From | Concern (ppb), % |                    |
| Acute Study,  | Study,      | Days Exceeded,   |                    |
| in Days)**    | ppb)**      | \# Days/Year     |                    |
|               |             | Exceeded**       |                    |
+---------------+-------------+------------------+--------------------+
|               |             | **Acute          | **Endangered       |
|               |             | Nontarget**      | Species**          |
|               |             |                  |                    |
|               |             | **(LC~50~ or     | **(LC~50~ or       |
|               |             | EC~50~ \* 0.5)** | EC~50~ \* 0.05)**  |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Low Flow      |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 92.9%, 339       | 99.3%, 362 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 90.9%, 332       | 99.1%, 362 days**  |
| (Low-end) (2) |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 77.8%, 284       | 96.5%, 352 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 77.2%, 282       | 96.3%, 351 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 73.9%, 270       | 95.2%, 347 days**  |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 59%, 215 days**  | 84.3%, 308 days**  |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 42.2%, 154       | 73.1%, 267 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Medium Flow   |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 98.6%, 360       | 99.9%, 364 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 98.1%, 358       | 99.8%, 364 days**  |
| (Low-end) (2) |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 92.7%, 338       | 99.3%, 362 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 92.3%, 337       | 99.2%, 362 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 90.1%, 329       | 99%, 361 days**    |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 76.9%, 281       | 96.6%, 353 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 56.7%, 207       | 89.6%, 327 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| High Flow     |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 99.2%, 362       | 99.9%, 365 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 99%, 361 days**  | 99.9%, 365 days**  |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 93.1%, 340       | 99.6%, 364 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 92.5%, 338       | 99.6%, 364 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 89.6%, 327       | 99.5%, 363 days**  |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 77.9%, 284       | 97.9%, 358 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 66.4%, 242       | 89%, 325 days**    |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+

Table 14. Average Exceedances, High Intermittent Dose

+---------------+-------------+------------------+--------------------+
| **Taxa        | **Endpoint  | **Levels of      |                    |
| (Duration of  | Value (From | Concern (ppb), % |                    |
| Acute Study,  | Study,      | Days Exceeded,   |                    |
| in Days)**    | ppb)**      | \# Days/Year     |                    |
|               |             | Exceeded**       |                    |
+---------------+-------------+------------------+--------------------+
|               |             | **Acute          | **Endangered       |
|               |             | Nontarget**      | Species**          |
|               |             |                  |                    |
|               |             | **(LC~50~ or     | **(LC~50~ or       |
|               |             | EC~50~ \* 0.5)** | EC~50~ \* 0.05)**  |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Low Flow      |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 96.1%, 351       | 99.6%, 364 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 95%, 347 days**  | 99.5%, 363 days**  |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 84.5%, 308       | 98.1%, 358 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 83.9%, 306       | 98%, 358 days**    |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 80.5%, 294       | 97.4%, 355 days**  |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 66.1%, 241       | 90.9%, 332 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 51.2%, 187       | 79.7%, 291 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Medium Flow   |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 99.3%, 363       | 99.9%, 365 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 99.2%, 362       | 99.9%, 365 days**  |
| (Low-end) (2) |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 95.9%, 350       | 99.7%, 364 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 95.7%, 349       | 99.7%, 364 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 94.2%, 344       | 99.6%, 363 days**  |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 84.3%, 308       | 98.4%, 359 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 68.1%, 249       | 93.8%, 342 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| High Flow     |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 99.8%, 364       | 100%, 365 days**   |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 99.8%, 364       | 100%, 365 days**   |
| (Low-end) (2) |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 96.6%, 353       | 99.9%, 365 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 96.2%, 351       | 99.9%, 365 days**  |
| (4)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 94.4%, 344       | 99.9%, 365 days**  |
| (High-end)    |             | days**           |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 83.7%, 306       | 99.6%, 363 days**  |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 72.7%, 265       | 93.9%, 343 days**  |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+

Table 15. Worst-Case Exceedances, Low Continuous Dose

+---------------+-------------+------------------+--------------------+
| **Taxa        | **Endpoint  | **Levels of      |                    |
| (Duration of  | Value (From | Concern (ppb), % |                    |
| Acute Study,  | Study,      | Days Exceeded,   |                    |
| in Days)**    | ppb)**      | \# Days/Year     |                    |
|               |             | Exceeded**       |                    |
+---------------+-------------+------------------+--------------------+
|               |             | **Acute          | **Endangered       |
|               |             | Nontarget**      | Species**          |
|               |             |                  |                    |
|               |             | **(LC~50~ or     | **(LC~50~ or       |
|               |             | EC~50~ \* 0.5)** | EC~50~ \* 0.05)**  |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Low Flow      |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 99.7%, 364       | 100%, 365 days**   |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Medium Flow   |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 99.8%, 364       | 100%, 365 days**   |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| High Flow     |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 99.9%, 365       | 100%, 365 days**   |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+

Table 16. Worst-Case Exceedances, High Continuous Dose

+---------------+-------------+------------------+--------------------+
| **Taxa        | **Endpoint  | **Levels of      |                    |
| (Duration of  | Value (From | Concern (ppb), % |                    |
| Acute Study,  | Study,      | Days Exceeded,   |                    |
| in Days)**    | ppb)**      | \# Days/Year     |                    |
|               |             | Exceeded**       |                    |
+---------------+-------------+------------------+--------------------+
|               |             | **Acute          | **Endangered       |
|               |             | Nontarget**      | Species**          |
|               |             |                  |                    |
|               |             | **(LC~50~ or     | **(LC~50~ or       |
|               |             | EC~50~ \* 0.5)** | EC~50~ \* 0.05)**  |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Low Flow      |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Medium Flow   |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| High Flow     |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+

Table 17. Worst-Case Exceedances, Low Intermittent Dose

+---------------+-------------+------------------+--------------------+
| **Taxa        | **Endpoint  | **Levels of      |                    |
| (Duration of  | Value (From | Concern (ppb), % |                    |
| Acute Study,  | Study,      | Days Exceeded,   |                    |
| in Days)**    | ppb)**      | \# Days/Year     |                    |
|               |             | Exceeded**       |                    |
+---------------+-------------+------------------+--------------------+
|               |             | **Acute          | **Endangered       |
|               |             | Nontarget**      | Species**          |
|               |             |                  |                    |
|               |             | **(LC~50~ or     | **(LC~50~ or       |
|               |             | EC~50~ \* 0.5)** | EC~50~ \* 0.05)**  |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Low Flow      |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 99.7%, 364       | 100%, 365 days**   |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 95.1%, 347       | 100%, 365 days**   |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Medium Flow   |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 99.8%, 364       | 100%, 365 days**   |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 96.4%, 352       | 100%, 365 days**   |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| High Flow     |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 99.9%, 365       | 100%, 365 days**   |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 96.7%, 353       | 100%, 365 days**   |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+

Table 18. Average Exceedances, 8 Dose

+---------------+-------------+------------------+--------------------+
| **Taxa        | **Endpoint  | **Levels of      |                    |
| (Duration of  | Value (From | Concern (ppb), % |                    |
| Acute Study,  | Study,      | Days Exceeded,   |                    |
| in Days)**    | ppb)**      | \# Days/Year     |                    |
|               |             | Exceeded**       |                    |
+---------------+-------------+------------------+--------------------+
|               |             | **Acute          | **Endangered       |
|               |             | Nontarget**      | Species**          |
|               |             |                  |                    |
|               |             | **(LC~50~ or     | **(LC~50~ or       |
|               |             | EC~50~ \* 0.5)** | EC~50~ \* 0.05)**  |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Low Flow      |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 99.9%, 365       | 100%, 365 days**   |
|               |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 98.6%, 360       | 100%, 365 days**   |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| Medium Flow   |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 99.1%, 362       | 100%, 365 days**   |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+
| Facilities on |             |                  |                    |
| High Flow     |             |                  |                    |
| Streams       |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 14          | **7 ppb\         | **0.7 ppb\         |
| (Low-end) (4) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW            | 18          | **9 ppb\         | **0.9 ppb\         |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (Low-end) (2) |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| ME            | 69          | **34.5 ppb\      | **3.45 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Alga       | 73          | **36.5 ppb\      | **3.65 ppb\        |
| (High-end)    |             | 100%, 365 days** | 100%, 365 days**   |
| (4)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW            | 95          | **47.5 ppb\      | **4.75 ppb\        |
| Invertebrates |             | 100%, 365 days** | 100%, 365 days**   |
| (High-end)    |             |                  |                    |
| (2)           |             |                  |                    |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 320         | **160 ppb\       | **16 ppb\          |
| (Low-end) (2) |             | 100%, 365 days** | 100%, 365 days**   |
+---------------+-------------+------------------+--------------------+
| FW Fish       | 1000        | **500 ppb\       | **50 ppb\          |
| (High-end)    |             | 99.3%, 363       | 100%, 365 days**   |
| (2)           |             | days**           |                    |
+---------------+-------------+------------------+--------------------+

Tier I once-through cooling tower modeling indicates that DDAC use will
result in acute and chronic risk to non-endangered and
endangered/threatened freshwater fish and acute risk to other aquatic
animals at all dosages modeled: 32 ppm, 63 ppm, 1000 ppm, and 1800 ppm.

**(2) Wood Leaching Model**

The DDAC wood treatment use was modeled using Krahn and Strub - 1990, to
estimate expected environmental concentrations (EEC\'s). The EEC is an
estimate of the amount of DDAC that will runoff from treated wood
exposed to the elements when stored outdoors. The chemical formulation,
retention of chemical by the wood, rough vs smooth wood surfaces, amount
and timing of precipitation, and storage site conditions are some of the
variables that affect the amount and timing of runoff. A total of 16
rain cycles of equal intensity and duration were used in this model.

Estimated Environmental Concentrations (EECs) are as follows:

> The leaching study indicates that 1.58% of DDAC was leached from the
> wood into water, therefore:
>
> (0.6 lb/ft3 )X (1 ft3 /0.0283168 m3 )x (0.4535924 kg/lb) X 0.03 =
> 0.2883328 kg/m3
>
> 30.81 m3 x 0.2883328 kg/m3 x 0.0158 leach rate = 0.1403598 Kg of DDAC
> = 140.3598 g of DDAC = 140359.8 mg of DDAC
>
> It is assumed that the water body close to the dock contains between 6
> acre feet (7400891 liters) to 24 acre foot (29603736 liters) of water.
> Using the following relationship the amount of DDAC in fresh water
> will be:
>
> (140359.8 mg of DDAC)/ 7400891 = 0.01896526mg/L =0.01896526 ppm of
> DDAC in water = 18.97 ppb of DDAC in water.
>
> The DDAC concentrations in different size fresh bodies are shown in
> Table 1:
>
> **Table 19. Concentration of DDAC (ppm and ppb) in different size
> water bodies**

+-----------------+---------+------+-----+-------------+-------------+
|                 |         |      |     | > DDAC In   | DDAC In     |
|                 |         |      |     | > Water     | Water (ppb) |
|                 |         |      |     | > (ppm)     |             |
+-----------------+---------+------+-----+-------------+-------------+
| > 1 Acre Foot   | > 1233  | > Li |     | >           | 113.8       |
|                 | 481.855 | ters |     | 0.113791578 |             |
+-----------------+---------+------+-----+-------------+-------------+
| > 6 Acre foot   | > 7400  | > Li |     | >           | 19.0        |
|                 | 891.132 | ters |     | 0.018965263 |             |
+-----------------+---------+------+-----+-------------+-------------+
| > 12 Acre foot  | > 1480  | > Li |     | >           | 9.50        |
|                 | 1782.26 | ters |     | 0.009482632 |             |
+-----------------+---------+------+-----+-------------+-------------+
| > 18 Acre foot  | > 222   | > Li |     | >           | 6.30        |
|                 | 02673.4 | ters |     | 0.006321754 |             |
+-----------------+---------+------+-----+-------------+-------------+
| > 24 Acre foot  | > 2960  | > Li |     | >           | 4.7         |
|                 | 3564.53 | ters |     | 0.004741316 |             |
+-----------------+---------+------+-----+-------------+-------------+
|                 |         |      |     |             |             |
+-----------------+---------+------+-----+-------------+-------------+

The maximum amount of leachate from the treated wood that was predicted
by this model totaled 18.97 ppb. The lowest predicted amount of leachate
was 4.7 ppb and the highest amount was 113.8 ppb. LOC values for fish
range from 160 to 800 ppb, for green algae was 14 ppb and for estuarine
invertebrates was 48 ppb. Freshwater invertebrates are the most
sensitive aquatic animals to DDAC with an acute LOC of 34.5 ppb.

**[Conclusions]{.underline}**:

[Once-through Cooling Tower Use]{.underline}

Tier I once-through cooling tower modeling indicates that DDAC use will
result in acute and chronic risk to all non-endangered and
endangered/threatened aquatic organisms at all dosages modeled: 32 ppm
and 63 ppm for continuous dosing and 1000 ppm and 1800 ppm for
intermittent dosing.

The high vs medium vs low water flow rate is based on size of the
facility. Generally, higher flow (e.g., \> 1000 MGD) would use more
chemical than smaller facilities, but the pattern does not hold true
across the board, probably because model input values are based on
different receiving water ("reach") data for individual facilities. This
model uses 7Q10 rainfall conditions, which is essentially the worst-case
drought of a 10 year period. Variables such as stream flow rate and DDAC
dissipation, degradation, and 1/2 life were not considered in this Tier
I model but should be considered in higher tier modeling. Field
monitoring is suggested in the absence of higher Tier modeling. Risk
mitigation recommendations should be based on dosing method (e.g.
intermittent vs continuous) and application rate instead of facility
size, however, risk mitigation is not recommended at this time.

[Wood Treatment Use]{.underline}

The maximum amount of leachate from treated wood per the Krahn and
Strub, 1990 model totaled 18.97 ppb. The lowest predicted amount of
leachate was 4.7 ppb and the highest amount was 113.8 ppb.
Non-endangered/threatened aquatic species (fish and invertebrates) are
not expected to be adversely affected - acute or chronic toxicity -
based on LOCs above. Endangered/threatened fish (freshwater warmwater
species) are not expected to be adversely affected by the wood treatment
use. However, green alga non-endangered/threatened species, and
freshwater fish coldwater species, freshwater and marine aquatic
invertebrates, and green algae endangered/threatened species are at risk
from the wood treatment use.

Due to the extreme sensitivity of freshwater and marine aquatic
invertebrates to DDAC, methods such as indoor or covered wood storage
and/or containment of runoff water via berms or plastic barriers in
outdoor storage areas are suggested. DDAC is tightly adsorbed to clay
and organic matter which greatly reduces potential for DDAC to leach
downward through soil to groundwater, and will serve to reduce surface
runoff as well. **The Tier I screening model is only intended as a
screening-level model, and, as such, has inherent uncertainties and
limitations which may result in inaccurate exposure estimations, further
refinement of the model is recommended before any regulatory action is
taken regarding the antisapstain uses of DDAC. An environmental
monitoring study of runoff from antisapstain treatment facilities is
needed to address the potential risks and to provide EECs for use in a
refined risk assessment. Additionally, impacts from the antisapstain use
could potentially be mitigated with precautions to prevent leaching and
runoff when wood is stored outdoors.**

> **C. Endangered Species Considerations**

Section 7 of the Endangered Species Act, 16 U.S.C. Section 1536(a)(2),
requires all federal agencies to consult with the National Marine
Fisheries Service (NMFS) for marine and andronomus listed species, or
the United States Fish and Wildlife Services (FWS) for listed wildlife
and freshwater organisms, if they are proposing an \"action\" that may
affect listed species or their designated habitat. Each federal agency
is required under the Act to insure that any action they authorize,
fund, or carry out is not likely to jeopardize the continued existence
of a listed species or result in the destruction or adverse modification
of designated critical habitat. To jeopardize the continued existence of
a listed species means \"to engage in an action that reasonably would be
expected, directly or indirectly, to reduce appreciably the likelihood
of both the survival and recovery of a listed species in the wild by
reducing the reproduction, numbers, or distribution of the species.\" 50
C.F.R. \' 402.02.

To facilitate compliance with the requirements of the Endangered Species
Act subsection (a)(2) the Environmental Protection Agency, Office of
Pesticide Programs has established procedures to evaluate whether a
proposed registration action may directly or indirectly reduce
appreciably the likelihood of both the survival and recovery of a listed
species in the wild by reducing the reproduction, numbers, or
distribution of any listed species (U.S. EPA 2004). After the Agency=s
screening-level risk assessment is performed, if any of the Agency=s
Listed Species LOC Criteria are exceeded for either direct or indirect
effects, a determination is made to identify if any listed or candidate
species may co-occur in the area of the proposed pesticide use. If
determined that listed or candidate species may be present in the
proposed use areas, further biological assessment is undertaken. The
extent to which listed species may be at risk then determines the need
for the development of a more comprehensive consultation package as
required by the Endangered Species Act.

For certain use categories, the Agency assumes there will be minimal
environmental exposure, and only a minimal toxicity data set is required
(Overview of the Ecological Risk Assessment Process in the Office of
Pesticide Programs U.S. Environmental Protection Agency - Endangered and
Threatened Species Effects Determinations, 1/23/04, Appendix A, Section
IIB, pg.81). Chemicals in these categories therefore do not undergo a
full screening-level risk assessment, and are considered to fall under a
Ano effect@ determination (NE). The majority of DDAC uses are spray
applications to indoor surfaces, truck interiors, kennels, institutional
areas, household areas, recirculating cooling towers, evaporative
condensers, pulp/paper mills, swimming pools and spas, and oil field mud
treatments to name a few and fall into this category for the following
reasons:

1.  The amount that will actually reach the environment is very small
    based on usage data and use patterns (no homeowner/residential use
    for bathrooms) and containment methods (retaining ponds,
    recirculation, low residual upon release).

2.  Breakdown in the environment and via sewage treatment is rapid and
    well documented in the literature (See Environmental Fate Chapter
    for more detail). The agency requires the following label statement:
    \"Do not discharge effluent containing this product into lakes,
    streams, ponds, estuaries, oceans, or other waters unless in
    accordance with the requirements of a National Pollutant Discharge
    Elimination System (NPDES) permit and the permitting authorities are
    notified in writing prior to discharge. Do not discharge effluent
    containing this product to sewer systems without previously
    notifying the local sewage treatment plant authority. For guidance
    contact your State Water Board or Regional Office of the EPA.\"
    There was no information in the Sewage Treatability Database on
    DDAC.

DDAC uses that have potential for direct release into the environment or
runoff to surface waters include once-through cooling tower and wood
treatment uses respectively. These uses are considered to be
representative of having worst-case potential for impacting the
environment. Therefore, these sites were modeled.

The "best case" once-through cooling tower scenario using 1/2 the
maximum recommended label dosage intermittently applied in a low water
flow resulted in LOC exceedances for all aquatic organisms used in the
model, including freshwater fish, green alga, freshwater invertebrates,
and marine invertebrates. The agency is not aware of any endangered or
threatened green algae. Because DDAC is rapidly adsorbed to organic
materials and clay, impacts to aquatic organisms may be less than
modeled. Aerobic aquatic metabolism study on DDAC (MRID# 422538-03)
provides a sediment half-life of 60 years. There is a potential for
sediment concentrations to reach toxic levels over time (aerobic soil
metabolism half-life of 2.8 years, MRID# 422538-01). The once-through
cooling tower model does not account for degradation and therefore,
further assessment is required prior to making an agency endangered
species determination.

Endangered/threatened coldwater fish species, marine and freshwater
invertebrates, and green algae species are expected to be adversely
affected by the wood treatment use. Impacts from the wood treatment use
are not expected to occur as long as precautions are taken to prevent
leaching when wood is stored outdoors. **Using Tier I screening modeling
to assess potential exposure from antisapstain wood preservation uses of
DDAC, risks to Listed Species are indicated. Since the model is only
intended as a screening-level model, and, as such, has inherent
uncertainties and limitations which may result in inaccurate exposure
estimations, further refinement of the model is recommended before any
regulatory action is taken regarding the antisapstain uses of DDAC. An
environmental monitoring study of runoff from antisapstain treatment
facilities is needed to address the potential risks and to provide EECs
for use in a refined risk assessment. Additionally, impacts from the
antisapstain use could potentially be mitigated with precautions to
prevent leaching and runoff when wood is stored outdoors. Due to these
circumstances, the Agency defers making a determination for the
antisapstain uses of DDAC until additional data and modeling refinements
are available. At that time, the environmental exposure assessment of
the antisapstain use of DDAC will be revised, and the risks to Listed
Species will be reconsidered.**

**IV. Confirmatory Data Required**

**1. Nontarget Plant Phytotoxicity Study is Required:** 850.4225
(seedling emergence

test using rice).

> **2. Acute Eastern Oyster embryo larvae study is required:** 850.1055
>
> **3. Chronic *Daphnia magna* is required:** 850.1300
>
> **4. Monitoring/Tier II modeling of once-through cooling tower and
> antisapstain uses to establish EEC's for risk assessment.**

**IV. Label Hazard Statements for Terrestrial and Aquatic Organisms and
Use Recommendations**

DDAC labels must state:

\"This pesticide is toxic to fish, aquatic invertebrates, oysters, and
shrimp\".

\"Do not discharge effluent containing this product into lakes, streams,
ponds, estuaries, oceans, or other waters unless in accordance with the
requirements of a National Pollutant Discharge Elimination System
(NPDES) permit and the permitting authorities are notified in writing
prior to discharge. Do not discharge effluent containing this product to
sewer systems without previously notifying the local sewage treatment
plant authority. For guidance contact your State Water Board or Regional
Office of the EPA.\"

Wood treatment labels must state: \"Treated lumber must not be stored
outdoors without precautions to prevent leaching by rainfall to the
environment. Suitable precautions include: covering wood with plastic or
other impervious covering, installation of berms and placement of
plastic under the wood to prevent surface water runoff away from the
storage area.\"

**REFERENCES**

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10-2D (50% active ingredient) to the bluegill sunfish.

Project \# 03890-1: Onyx Chemical Co. (1982b) The acute toxicity of
10-2D (50% active ingredient) to the rainbow trout.

Project \# 03890-1: Onyx Chemical Co. (1982c) The acute toxicity of
10-2D (50% active ingredient) to the Daphnia magna.

No. 7E-6686: Roberts, S. (1977) Report: Static 48-hour toxicity study of
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ACC \# 007958: Wells Labs. (1971a) Report on fish toxicity using Bardac
22 bluegill sunfish.

ACC \# 007958: Wells Labs. (1971b) Report on fish toxicity (rainbow
trout) toxicity testing Barbac 22.

ACC \# 132164: Cannon Lab. (1973) Report eight day dietary LC~50~ study
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ACC# 225596: Cannon Lab. (1976) Report static 48 hour toxicity study of
BARDAC 22 to Daphnide.

ACC# 225596: Cannon Lab. (1977) Report Acute oral LD~50~ toxicity study
of BARDAC 22 to Mallard Duck.

ACC \# 249002: Cannon Lab. (1974a) Report: 48 hour EC~50~ and 96 hour
LC~50~ of Calgon JJ-14 (Bardac 22) on oyster eggs and straight-hinge
larvae.

ACC# 249002: Cannon Lab. (1974b) Report: 96 hour LC~50~ determination of
Calgon JJ-14 (Bardac 22) in marine blue crab.

ACC# 249002: Cannon Lab. (1974c) Report: 96 hour LC~50~ determination of
Calgon JJ-14 (Bardac 22) in marine grass shrimp.

ACC# 258798: Fink, R. and Beavers, J. (1982) Eight-day dietary LC~50~ --
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International, Ltd.

ACC# 258798: Fink, R. and Beavers, J. (1985) Eight-day dietary LC~50~ --
bobwhite quail: 10-2D: final report: project no. 183-104. Wildlife
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ACC# 401298-01: Henck, J.H. (1986) Avian Eight-day dietary toxicity test
in bobwhite quail. TRL Study No. 014-064. Toxicity Research
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ACC# 401298-01: Surprenant, D.C. (1986) Acute toxicity of Maquat MQ
416M: Report No. BW-86-12-2263; Springborn Bionomics, Inc.

ACC#s 401298-01, -02, -03: Surprenant, D.C. (1987) Acute Toxicity of
Maquat MQ 416M to Daphnids (*Daphnia pulex*). Springborn Bionomics, Inc.

MRID# 415780-01: LeLievre, M.K. (1990a) Evaluation of
Didecyldimethylammoniumchloride (DDAC) in a static acute toxicity with
bluegill sunfish, *Lepomis macrochirus*. Springborn Laboratories, Inc.

MRID# 415780-02: LeLievre, M.K. (1990c) Evaluation of
Didecyldimethylammoniumchloride (DDAC) in a static acute toxicity test
with daphnids, *Daphnia magna*. Springborn Laboratories, Ic.

MRID# 415780-03: LeLievre, M.K. (1990b) Evaluation of
Didecyldimethylammoniumchloride (DDAC) in a static acute toxicity test
with coho salmon, *Oncorhynchus kisutch*. Springborn Laboratories, Inc.

MRID# 415780-04: LeLievre, M.K. (1990d) Evaluation of
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MRID# 415920-02: Rhodes, J.E. (2000a) Acute toxicity of P198 to the
bluegill sunfish, *Lepomis macrochirus*, determined under static
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northern bobwhite. Wildlife International, Ltd.

MRID# 417858-02: Long, R.D., Hoxter, K.A. and Smith, G.J. (1991b)
Didecyldimethylammoniumchloride: A dietary LC~50~ study with the
mallard.

MRID# 417858-03: Campbell, S., Hoxter, K.A., and Smith, G.J. (1991)
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MRID# 422538-01: Cranor, W. 1991. Aerobic Soil Metabolism of

\[^14^C\]Didecyldimethylammonium chloride (^14^C-DDAC). Final Report.
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MRID# 458964-01: Krueger, H.O., Desjardins, D., Kendall, T., and
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(*Selenastrum capricornutum*). Wildlife International, Ltd.

**ADDITIONAL REFERENCES:**

Bailey, H.C., Elphick, J.R., Potter, A., Chao, E. and Zak, B. (1999)
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Juvenile white sturgeon (*Acipenser transmontanus*). Water Qual. Res.
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Teh, S.J., Wong, C., Furtula, V. and Teh, F. (2003) Lethal and sublethal
toxicity of Dedecyldimethylammonoiumchloride in early life stages of
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Woods, A.W., Blair, D., Johnston, A.P., Farrell, P. and Kennedy, C.J.
(1996) Effects of idiecyldimethylammonium chloride (DDAC) on the
swimming performance, gill morphology, disease resistance, and
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