Document ID: EPA-HQ-OPP-2006-0338-0022
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2006-12-29T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

                                                                        
                                    PREVENTION, PESTICIDES AND 

                                                                        
                                             TOXIC SUBSTANCES

					

August 2, 2006

MEMORANDUM  

                                                                        

	

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				PC Code	CAS#		Common Name

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

08/02/2006

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…………………………………………………………
………………4

II.  Ecological Toxicity Data . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Toxicity to Terrestrial Animals . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . 5

1.  Birds, Acute and Subacute
………………………………………………..…5

Mammals, Acute and Chronic . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . 7

                        3.  Non-target Insects,
Honeybee……………………………………………7

             

            B.  Toxicity to Aquatic Animals
………..…………………………………………..7 

1.  Freshwater Fish, Acute . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . .  7

2.  Freshwater Fish, Chronic
………………………….………………….…10

3.  Freshwater Invertebrates,
Acute………………….……………………...10

4.  Freshwater Invertebrates, Chronic
………………………………………11

5.  Estuarine and Marine Organisms
………………………………………..11 

              C.  Toxicity to Plants . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 

III.  Risk Assessment and Risk Characterization . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . .13

A.  Environmental Fate Assessment Summary . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . 15

B.  Environmental Exposure Assessment
…………………………………………..15

C.  Endangered Species Considerations . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . .  . . . . 27

III.  Confirmatory Data Required. . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . .. . . . . . 29

IV.  Label Hazard Statements for Terrestrial and Aquatic Organisms. . .
. . . . . . . .  . . . . . . 30

V.  References . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . .  . . . . . . 31

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

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 Organism  	Results LC50 (mg/L) or LD50 (mg/kg)	Toxicity
Category	Comments	Reference

Avian dietary LC50 Bobwhite Quail (Colinus virginianus)	229

NOEC  <31	Practically non-toxic	Core study	Long et al. 1991a 

MRID# - 41785801  

Avian dietary LC50  Mallard Duck (Anas                                  
                                                     platyrhynchos )
>5620

NOEC = 562	Practically non-toxic	Core study	Long et al. 1991b

MRID# - 41785802 

Avian single dose oral LD50 Bobwhite Quail (Colinus virginianus)	217

	Moderately toxic	Core Study	Campbell et al. 1991

MRID# - 41785803

Eight day dietary LC50 Bobwhite Quail (Colinus virginianus)	>5000
Practically non-toxic

	Supplemental Study	Henck, H.W. 1986

ACC# - 40129801

8-day dietary LC50 Mallard Duck (Anas platyrhynchos) 	>5620 	Practically
non-toxic	Core Study	Fink, R. and Beavers J. 1985

ACC# - 258798

8-day dietary LC50 Bobwhite Quail (Colinus virginianus)	>5620
Practically non-toxic	Core Study

	Fink, R. and Beavers, J. 1982

ACC# - 258798

Acute Oral LD50 Bobwhite Quail (Colinus virginianus)	54.4 	Moderately
toxic 	Core Study	Fink, R. and Beavers, J. 1985 

ACC# - 258798

8-day dietary LC50 Bobwhite Quail (Colinus virginianus)	1950 + 236.6
None given	Supplemental Study	Cannon Lab. 1973

ACC# - 132164

8-day dietary LC50 Mallard Duck (Anas platyrhynchos)	>3500	None given
Supplemental Study	Cannon Lab. 1973

ACC# - 132164

Acute Oral Toxicity LD50 Mallard Duck (Anas platyrhynchos) 	0.33 gm/kg
None given	Supplemental Study	Cannon Lab. 1977

ACC# - 225889

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”.

Non-target Insects, Honeybees

Honeybees could be exposed to pesticide residues if treated wood were
used to construct hives or hive components.  These residues may be toxic
to the bees, or result in residues in honey or other hive products
intended for human use/consumption.  Therefore, a special honeybee study
is required for all wood preservative unless a statement prohibiting the
use of treated wood in hive construction is added to the label, such as,
“Wood treated with DDAC shall not be used in the construction of
beehives.”  This study is a combination of Guidelines 171-4 and
850.3030 (see information regarding residue data requirements for uses
in beehives in the residue chemistry section of 40 CFR part 158). 
Numbers of bees used in this study and methods for
collection/introduction of bees into hives, feeding, and observations
for toxicity and mortality should be consistent with those described in
OPPTS Guideline 850.3030, “Honey Bee Toxicity of Residues on
Foliage.”).  The toxicity portion of this study is in lieu of the
honeybee contact LD50 test .

       

 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 LC50 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 (Acipenser transmontanus)	Larvae: 24-h LC50 = 0.74 ppb
(0.1, 1.0); 100% mortality at >1.0 ppb; NOEC = 0.5 ppb 

Fry: 100% mortality at 10.0 ppb    	8 day old larvae

42 day old fry

96 hour test duration

no mortality in control groups	Bennett, W.R. and Farrell, A.P. 1998.

Water Qual. Res. J. Can. 33(1)95-110.

Rainbow Trout (Oncorhynchus mykiss)	96-h LC50 = 0.409 mgL-1	96 hour test
duration

flow-through system 	Wood, A.W. et. al. 1996. Can. J. Fish. Aquat. Sci.
53:2424-2432.   

Japanese Makata (Oryzias latipes) and Zebrafish (Danio rerio)	IC25 =
439.7 + 9.9 ug/l (NOEC = 312.5 ug/l) for zebrafish;

IC25 = 1563 + 14.5 ug/l (NOEC = 1250 ug/l) for makata 	9 day test for
zebrafish

14 day test for makata	Tatarazako, N. et al. 2002. Health Sci.
48(4):359-365.

White Sturgeon (Acipenser transmontanus)	LC50 = 10 to 50 ug/l for 3 day,
58.5 ug/l for 11 day, 99.7 ug/l for 42 day old larvae; LC50 = 100 to 250
ug/l for 78 day old juveniles	96-hr. static renewal method using 3, 11,
42 day larvae, and

78 day old juveniles  	Teh, S.J. et al. 2003. Toxicol. Chem.
22(9):2152-2158. 

Rainbow Trout (Orcorhynchus mykiss)	LC50 = 537 ug/l	96-hr. test using
juvenile rainbow trout	Bailey, H.C. et al. 1999. Water 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 Organism 	Results LC50 (mg/L)	Toxicity Category	Comments
Reference

Acute Toxicity LC50 Rainbow Trout (Onchorynchus mykiss)	478	Practically
non-toxic	Supplemental Study	Rhodes, R.E. 2000a

MRID# - 41592002

Acute Toxicity LC50 Bluegill Sunfish (Lepomis macrochirus)	188
Practically non-toxic 	Supplemental Study	Rhodes, R.E. 2000b

MRID# - 45192001

Static Acute Toxicity LC50 Sheepshead minnow (Cyprindon variegates)	0.96
Highly toxic	Core Study	Collins, M.K. 1994

MRID# - 43620001

Static Acute Toxicity LC50 Bluegill Sunfish (Lepomis macrochirus) 	0.32
Highly toxic	Core Study	LeLievre, M.K. 1990a

MRID# - 41578001

Static Acute Toxicity LC50 Coho Salmon (Oncorhynchus kisutch)	1.0	Highly
toxic 	Core Study	LeLievre, M.K. 1990b 

MRID# - 41578003

Acute Toxicity 96-hr LC50 Blue gill sunfish (Lepomis macrochirus) 	0.5
Highly toxic	Core Study	Onyx Chemical Co. 1982a 

PROJ# - 038901

Acute Toxicity 96-hr LC50 Rainbow Trout (Oncorhynchus mykiss)	2.8
Moderately toxic	Core Study	Onyx Chemical Co. 1982b

PROJ# - 038901

Acute Toxicity 96-hr LC50 Rainbow Trout (Oncorhynchus mykiss)	1.6
Moderately toxic	Core Study	Surpremant, D.C. 1986

ACC# - 40129801

96 hr. Static Bioassay LC50 Bluegill Sunfish (Lepomis macrochirus)	0.27
Not given	Supplemental	Wells Labs 1971a

ACC# - 007958

96 hr. Static Bioassay LC50 Rainbow Trout (Oncorhynchus mykiss) 	1.1	Not
given	Supplemental	Wells Labs 1971b

ACC# - 007958 

                                 

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 Organism	Results 	Toxicity Category	Comments	Reference

Freshwater invertebrate static acute toxicity  Daphnia magna	48-hr. EC
50 = 94 ug/l	Very highly toxic	Core Study	LeLievre, M.K. 1990c

MRID# - 41578002 

Freshwater Invertebrate Static Acute Toxicity Daphnia magna	48-hr. LC50
= 0.018 mg/l 	Very highly toxic	Core Study	Onyx Chemical Co. 1982c

PROJ# - 038901

Acute Toxicity Daphnia pulex	48-hr. LC50 = 0.052 mg/l 	Very highly toxic
Core Study	Surprenant, E.C. 1987

ACC# - 40129801, 02, 03

Static 48-hr. toxicity study Daphnia magna	48-hr. LC50 = 0.095 mg/l	None
given	Supplemental Study 	Roberts, S. 1977

No. - 7E-6686

48-hr. Static aquatic invertebrate study Daphnia magna 	48-hr. LC50 =
0.1 mg/l	None given	Supplemental Study	Cannon Labs 1976

ACC# - 225596

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	IC25 = 211.2 + 6.8 ug/l (NOEC = 125 ug/l)	21 day test
Tatarazako, N. et al. 2002. Health Sci. 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 Organism	Results	Toxicity Category	Comments	Reference

Whole Sediment  chronic toxicity invertebrate test Midge (Chironomus
tentans)	LC50 = >1000 (mg ai/kg dry sediment)

EC50 = 1981	None given	Supplemental Study	England, D.C. and Leak, T.
1995

MRID# - 45821701

 

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 Organism	Results	Toxicity Category	Comments	Reference

Estuarine Invertebrate Static Acute Toxicity Mysid Shrimp (Mysidopsis
bahia)	96-hr. LC50 = 69 ug/l 	Very highly toxic 	Core Study	LeLievre, M.
K. 1990d

MRID# -  41578004

48-hr. EC50 and 96-hr. LC50 oyster eggs and straight-hinge larvae 	Eggs:
9-hr. 

EC50 = 19 ppm

Larvae: 48-hr. LC50 = 10.5 ppm; 96-hr. LC50 = 6.4 ppm 	None given	Core
Study	Cannon Labs 1974a

ACC# - 249002

96-hr. LC50 marine blue crab	96-hr. LC50 = 2.10 + 1.28 ppm	None given
Core Study	Cannon Labs 1974b

ACC# - 249002

96-hr. LC50 marine grass shrimp	96-hr. LC50 = 2.78 + 0.29	None given
Core Study	Cannon Labs 1974c

ACC   # - 249002

    

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.        

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 Organism	Results	Toxicity Category	Comments	Reference

96-hr. Toxicity Test Freshwater Alga (Selenastrum capricornutum)

Using natural surface water	EC10 = 9.64 ug ai/L

EC50 = 73.2 ug ai/L

NOEC = 27 ug ai/L	None given	Supplemental Study	Krueger, H.O. et al.
2003

MRID# - 45896401

 96-hr Toxicity Test with Freshwater Alga (Selenastrum capricornutum)
96-hr EC10 = 6.56 ug/L

EC50 = 14.22 ug/L 

NOEC =  8 ug/L	None given	Core Study	Krueger, H.O. et al. 2002

MRID# - 45896402

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 (Selenastrum capricornutum)	IC25 = 10 + 24.4 ug/l (NOEC = 25
ug/l)	72-hr test 	Tatarazako, N. 2002 Health Sci. 48(4): 359-365.  

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) LC50 (fish and birds) (2) LD50 (birds and mammals) (3) EC50 (aquatic
plants and aquatic invertebrates) and (4) EC25 (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	

EEC1/LC50 or LD50/sqft2 or LD50/day3	

0.5

Acute Restricted Use	

EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 50 mg/kg)	

0.2

Acute Endangered Species	

EEC/LC50 or LD50/sqft or LD50/day 	

0.1

Chronic Risk	

EEC/NOEC	

1

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

 2    mg/ft2             	3 mg of toxicant consumed/day

   LD50 * wt. of bird             	LD50 * wt. of bird  

 

Risk Presumptions for Aquatic Animals	 

Risk Presumption	

RQ 	

LOC

Acute High Risk	

EEC1/LC50 or EC50	

0.5

Acute Restricted Use	

EEC/LC50 or EC50	

0.1

Acute Endangered Species	

EEC/LC50 or EC50	

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 

 tc \l2 "Terrestrial and Semi-Aquatic Plants  

Acute High Risk	

EEC1/EC25	

1

Acute Endangered Species	

EEC/EC05 or NOEC	

1



Aquatic Plants

 tc \l2 "Aquatic Plants 

Acute High Risk	

EEC2/EC50	

1

Acute Endangered Species	

EEC/EC05 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.

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 Risk LOC (X 0.5)	Restricted Use LOC (X 0.1)
Endangered Species LOC (X 0.05)

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

Freshwater fish – cold	1600 ppb	800 ppb	160 ppb	80 ppb

Freshwater invertebrate	94 ppb	47 ppb	9.4 ppb	4.7 ppb

Marine fish	96 ppb	48 ppb	9.6 ppb	4.8 ppb

Marine mollusk	No data

	Marine invertebrate	69 ppb	34.5 ppb	6.9 ppb	3.45 ppb

Green alga	14 ppb	7 ppb	1.4 ppb	0.7 ppb

Aquatic vascular plant	No data

	Freshwater fish chronic	No data

	 

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 (Duration of Acute Study, in Days)	Endpoint Value 

(From Study, ppb)	Levels of Concern (ppb), % Days Exceeded, # Days/Year
Exceeded

Acute Nontarget 

(LC50 or EC50 * 0.5)	Endangered Species 

(LC50 or EC50 * 0.05)

Facilities on Low Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

98.2%, 358 days	0.7 ppb

99.8%, 364 days

FW Invertebrates (Low-end) (2)	18	9 ppb

97.7%, 357 days	0.9 ppb

99.8%, 364 days

ME Invertebrates (4)	69	34.5 ppb

89.9%, 328 days	3.45 ppb

99.1%, 362 days

FW Alga (High-end) (4)	73	36.5 ppb

89.3%, 326 days	3.65 ppb

99.1%, 362 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

86.2%, 315 days	4.75 ppb

98.8%, 361 days

FW Fish (Low-end) (2)	320	160 ppb

72.4%, 264 days	16 ppb

95.5%, 349 days

FW Fish (High-end) (2)	1000	500 ppb

58.5%, 214 days	50 ppb

85.5%, 312 days

Facilities on Medium Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

99.7%, 364 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

99.6%, 364 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

97.8%, 357 days	3.45 ppb

99.9%, 364 days

FW Alga (High-end) (4)	73	36.5 ppb

97.6%, 356 days	3.65 ppb

99.8%, 364 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

96.7%, 353 days	4.75 ppb

99.8%, 364 days

FW Fish (Low-end) (2)	320	160 ppb

89.5%, 327 days	16 ppb

99.3%, 362 days

FW Fish (High-end) (2)	1000	500 ppb

76.5%, 279 days	50 ppb

96.5%, 352 days

Facilities on High Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

98.6%, 360 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

98.4%, 359 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

97.6%, 356 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

89.2%, 326 days	16 ppb

99.9%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

77.5%, 283 days	50 ppb

97.4%, 355 days

Table 12.  Average Exceedances, High Continuous Dose

Taxa (Duration of Acute Study, in Days)	Endpoint Value (From Study, ppb)
Levels of Concern (ppb), % Days Exceeded, # Days/Year Exceeded

Acute Nontarget 

(LC50 or EC50 * 0.5)	Endangered Species 

(LC50 or EC50 * 0.05)

Facilities on Low Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

99.6%, 363 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

99.4%, 363 days	0.9 ppb

99.9%, 365 days

ME Invertebrates (4)	69	34.5 ppb

95.1%, 347 days	3.45 ppb

99.8%, 364 days

FW Alga (High-end) (4)	73	36.5 ppb

94.7%, 346 days	3.65 ppb

99.8%, 364 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

92.5%, 338 days	4.75 ppb

99.7%, 364 days

FW Fish (Low-end) (2)	320	160 ppb

80.4%, 293 days	16 ppb

98.8%, 360 days

FW Fish (High-end) (2)	1000	500 ppb

66.7%, 243 days	50 ppb

92%, 336 days

Facilities on Medium Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

99.9%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

99.9%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

99.1%, 362 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

99%, 361 days	3.65 ppb

99.9%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

98.6%, 360 days	4.75 ppb

99.9%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

94.3%, 344 days	16 ppb

99.8%, 364 days

FW Fish (High-end) (2)	1000	500 ppb

84.8%, 310 days	50 ppb

98.5%, 360 days

Facilities on High Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

99.7%, 364 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

99.7%, 364 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

99.5%, 363 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

94.9%, 346 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

84.1%, 307 days	50 ppb

99.4%, 363 days

Table 13.  Average Exceedances, Low Intermittent Dose

Taxa (Duration of Acute Study, in Days)	Endpoint Value (From Study, ppb)
Levels of Concern (ppb), % Days Exceeded, # Days/Year Exceeded

Acute Nontarget 

(LC50 or EC50 * 0.5)	Endangered Species

 (LC50 or EC50 * 0.05)

Facilities on Low Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

92.9%, 339 days	0.7 ppb

99.3%, 362 days

FW Invertebrates (Low-end) (2)	18	9 ppb

90.9%, 332 days	0.9 ppb

99.1%, 362 days

ME Invertebrates (4)	69	34.5 ppb

77.8%, 284 days	3.45 ppb

96.5%, 352 days

FW Alga (High-end) (4)	73	36.5 ppb

77.2%, 282 days	3.65 ppb

96.3%, 351 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

73.9%, 270 days	4.75 ppb

95.2%, 347 days

FW Fish (Low-end) (2)	320	160 ppb

59%, 215 days	16 ppb

84.3%, 308 days

FW Fish (High-end) (2)	1000	500 ppb

42.2%, 154 days	50 ppb

73.1%, 267 days

Facilities on Medium Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

98.6%, 360 days	0.7 ppb

99.9%, 364 days

FW Invertebrates (Low-end) (2)	18	9 ppb

98.1%, 358 days	0.9 ppb

99.8%, 364 days

ME Invertebrates (4)	69	34.5 ppb

92.7%, 338 days	3.45 ppb

99.3%, 362 days

FW Alga (High-end) (4)	73	36.5 ppb

92.3%, 337 days	3.65 ppb

99.2%, 362 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

90.1%, 329 days	4.75 ppb

99%, 361 days

FW Fish (Low-end) (2)	320	160 ppb

76.9%, 281 days	16 ppb

96.6%, 353 days

FW Fish (High-end) (2)	1000	500 ppb

56.7%, 207 days	50 ppb

89.6%, 327 days

Facilities on High Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

99.2%, 362 days	0.7 ppb

99.9%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

99%, 361 days	0.9 ppb

99.9%, 365 days

ME Invertebrates (4)	69	34.5 ppb

93.1%, 340 days	3.45 ppb

99.6%, 364 days

FW Alga (High-end) (4)	73	36.5 ppb

92.5%, 338 days	3.65 ppb

99.6%, 364 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

89.6%, 327 days	4.75 ppb

99.5%, 363 days

FW Fish (Low-end) (2)	320	160 ppb

77.9%, 284 days	16 ppb

97.9%, 358 days

FW Fish (High-end) (2)	1000	500 ppb

66.4%, 242 days	50 ppb

89%, 325 days

Table 14.  Average Exceedances, High Intermittent Dose

Taxa (Duration of Acute Study, in Days)	Endpoint Value (From Study, ppb)
Levels of Concern (ppb), % Days Exceeded, # Days/Year Exceeded

Acute Nontarget 

(LC50 or EC50 * 0.5)	Endangered Species 

(LC50 or EC50 * 0.05)

Facilities on Low Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

96.1%, 351 days	0.7 ppb

99.6%, 364 days

FW Invertebrates (Low-end) (2)	18	9 ppb

95%, 347 days	0.9 ppb

99.5%, 363 days

ME Invertebrates (4)	69	34.5 ppb

84.5%, 308 days	3.45 ppb

98.1%, 358 days

FW Alga (High-end) (4)	73	36.5 ppb

83.9%, 306 days	3.65 ppb

98%, 358 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

80.5%, 294 days	4.75 ppb

97.4%, 355 days

FW Fish (Low-end) (2)	320	160 ppb

66.1%, 241 days	16 ppb

90.9%, 332 days

FW Fish (High-end) (2)	1000	500 ppb

51.2%, 187 days	50 ppb

79.7%, 291 days

Facilities on Medium Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

99.3%, 363 days	0.7 ppb

99.9%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

99.2%, 362 days	0.9 ppb

99.9%, 365 days

ME Invertebrates (4)	69	34.5 ppb

95.9%, 350 days	3.45 ppb

99.7%, 364 days

FW Alga (High-end) (4)	73	36.5 ppb

95.7%, 349 days	3.65 ppb

99.7%, 364 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

94.2%, 344 days	4.75 ppb

99.6%, 363 days

FW Fish (Low-end) (2)	320	160 ppb

84.3%, 308 days	16 ppb

98.4%, 359 days

FW Fish (High-end) (2)	1000	500 ppb

68.1%, 249 days	50 ppb

93.8%, 342 days

Facilities on High Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

99.8%, 364 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

99.8%, 364 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

96.6%, 353 days	3.45 ppb

99.9%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

96.2%, 351 days	3.65 ppb

99.9%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

94.4%, 344 days	4.75 ppb

99.9%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

83.7%, 306 days	16 ppb

99.6%, 363 days

FW Fish (High-end) (2)	1000	500 ppb

72.7%, 265 days	50 ppb

93.9%, 343 days

Table 15.  Worst-Case Exceedances, Low Continuous Dose

Taxa (Duration of Acute Study, in Days)	Endpoint Value (From Study, ppb)
Levels of Concern (ppb), % Days Exceeded, # Days/Year Exceeded

Acute Nontarget 

(LC50 or EC50 * 0.5)	Endangered Species 

(LC50 or EC50 * 0.05)

Facilities on Low Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

100%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

99.7%, 364 days	50 ppb

100%, 365 days

Facilities on Medium Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

100%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

99.8%, 364 days	50 ppb

100%, 365 days

Facilities on High Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

100%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

99.9%, 365 days	50 ppb

100%, 365 days

Table 16.  Worst-Case Exceedances, High Continuous Dose

Taxa (Duration of Acute Study, in Days)	Endpoint Value (From Study, ppb)
Levels of Concern (ppb), % Days Exceeded, # Days/Year Exceeded

Acute Nontarget

 (LC50 or EC50 * 0.5)	Endangered Species 

(LC50 or EC50 * 0.05)

Facilities on Low Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

100%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

100%, 365 days	50 ppb

100%, 365 days

Facilities on Medium Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

100%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

100%, 365 days	50 ppb

100%, 365 days

Facilities on High Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

100%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

100%, 365 days	50 ppb

100%, 365 days

Table 17.  Worst-Case Exceedances, Low Intermittent Dose

Taxa (Duration of Acute Study, in Days)	Endpoint Value (From Study, ppb)
Levels of Concern (ppb), % Days Exceeded, # Days/Year Exceeded

Acute Nontarget 

(LC50 or EC50 * 0.5)	Endangered Species 

(LC50 or EC50 * 0.05)

Facilities on Low Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

99.7%, 364 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

95.1%, 347 days	50 ppb

100%, 365 days

Facilities on Medium Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

99.8%, 364 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

96.4%, 352 days	50 ppb

100%, 365 days

Facilities on High Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

99.9%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

96.7%, 353 days	50 ppb

100%, 365 days

Table 18.  Average Exceedances, 8 Dose

Taxa (Duration of Acute Study, in Days)	Endpoint Value (From Study, ppb)
Levels of Concern (ppb), % Days Exceeded, # Days/Year Exceeded

Acute Nontarget 

(LC50 or EC50 * 0.5)	Endangered Species 

(LC50 or EC50 * 0.05)

Facilities on Low Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

99.9%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

98.6%, 360 days	50 ppb

100%, 365 days

Facilities on Medium Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

100%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

99.1%, 362 days	50 ppb

100%, 365 days

Facilities on High Flow Streams

FW Alga (Low-end) (4)	14	7 ppb

100%, 365 days	0.7 ppb

100%, 365 days

FW Invertebrates (Low-end) (2)	18	9 ppb

100%, 365 days	0.9 ppb

100%, 365 days

ME Invertebrates (4)	69	34.5 ppb

100%, 365 days	3.45 ppb

100%, 365 days

FW Alga (High-end) (4)	73	36.5 ppb

100%, 365 days	3.65 ppb

100%, 365 days

FW Invertebrates (High-end) (2)	95	47.5 ppb

100%, 365 days	4.75 ppb

100%, 365 days

FW Fish (Low-end) (2)	320	160 ppb

100%, 365 days	16 ppb

100%, 365 days

FW Fish (High-end) (2)	1000	500 ppb

99.3%, 363 days	50 ppb

100%, 365 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 Water (ppm)	DDAC In Water (ppb)

1 Acre Foot	1233481.855	Liters

0.113791578	113.8

6 Acre foot	7400891.132	Liters

0.018965263	19.0

12 Acre foot	14801782.26	Liters

0.009482632	9.50

18 Acre foot	22202673.4	Liters

0.006321754	6.30

24 Acre foot	29603564.53	Liters

0.004741316	 4.7

	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.  

3.  Non-target Insects

Honeybees can be exposed to pesticide residues if treated wood is used
to construct hives or hive components.  These residues may be toxic to
the bees or result in residues in honey or other hive products intended
for human use/consumption.  Therefore, a special honeybee study is
required for all wood preservative uses unless a statement prohibiting
the use of treated wood in hive construction is added to the label such
as, “Wood treated with TCMTB shall not be used in the construction of
beehives.”  This study is a combination of Guidelines 171-4 and
850.3030 (see information regarding residue data requirements for uses
in beehives in the residue chemistry section of 40 CFR part 158). 
Numbers of bees used in this study and methods for
collection/introduction of bees into hives, feeding, and observations
for toxicity and mortality should be consistent with those described in
OPPTS Guideline 850.3030, “Honey Bee Toxicity of Residues on
Foliage.”  The toxicity portion of this study is in lieu of the
honeybee contact LD50 test.

Conclusions:

Once-through Cooling Tower Use

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

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
(no 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:

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).  

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.   Non-target Plant Phytotoxicity Studies are Required:  850.4225
(seedling 	                              emergence using rice), 850.4250
(vegetative vigor using rice), 850.4400 (Lemna                          
gibba), 850.5400 (Algal toxicity, 3 species:  blue-green cyanobacteria 
Anabeana flos-aquae,                         freshwater diatom Navicula
pelliculosa, marine diatom Skeletonema costatum).

2.  Acute Eastern Oyster embryo larvae study is required:  850.1055  

3.  Chronic Daphnia magna is required:  850.1300

4.   Honeybee toxicity studies:  Guidelines 171-4 and 850.3030 (see
information regarding residue data requirements for uses in beehives in
the residue chemistry section of 40 CFR part 158).  Numbers of bees used
in this study and methods for collection/introduction of bees into
hives, feeding, and observations for toxicity and mortality should be
consistent with those described in OPPTS Guideline 850.3030, “Honey
Bee Toxicity of Residues on Foliage.”  The toxicity portion of this
study is in lieu of the honeybee contact LD50 test.

            5.  Monitoring and/or Tier II modeling of once-through
cooling tower effluents to                                              
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
      establish EEC's for risk assessment, and to evaluate efficacy of
bentonite clay treatment.

            6.  Confirm the efficacy of antisapstain mitigation methods.

                                                                        
           

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."

Antisapstain labels must state:  

"Treated lumber must be stored under cover, indoors, or at least 100
feet from any pond, lake, stream, wetland, or river to prevent possible
runoff of the product into the waterway.  Treated lumber stored within
100 feet of a pond, lake, steam, wetland, or river must be either
covered with plastic or surrounded by a berm to prevent surface water
runoff into the nearby waterway.  If a berm or curb is used around the
site, it should consist of impermeable material (clay, asphalt,
concrete) and be of sufficient height to prevent runoff during heavy
rainfall events."

If studies 850.3030 and 171-4 are waived, the following statement on
antisapstain labels is required:  “Wood treated with DDAC shall not be
used in the construction of beehives.”

All once-thru cooling tower labels must state:  

“DO NOT APPLY THIS PRODUCT MORE THAN 4 TIMES PER YEAR”

“DEACTIVATION:  This product must be deactivated prior to discharge of
the NPDES outfall.  To deactivate:  Use bentonite clay at a minimum
ratio of 5 ppm clay to 1 ppm product.  Deactivation must occur prior to
discharge of the NPDES outfall.”



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 Bardac 22 in daphnids. Cannon Laboratories.

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 LC50 study of
JJ-14 (BARDAC 22) on bobwhite quail and mallard duck.      

ACC# 225596:  Cannon Lab. (1976) Report static 48 hour toxicity study of
BARDAC 22 to Daphnide. 

ACC# 225596:  Cannon Lab. (1977) Report Acute oral LD50 toxicity study
of BARDAC 22 to Mallard Duck. 

ACC # 249002:  Cannon Lab. (1974a) Report: 48 hour EC50 and 96 hour LC50
of Calgon JJ-14 (Bardac 22) on oyster eggs and straight-hinge larvae. 

ACC# 249002:  Cannon Lab. (1974b) Report: 96 hour LC50 determination of
Calgon JJ-14 (Bardac 22) in marine blue crab. 

ACC# 249002:  Cannon Lab. (1974c) Report: 96 hour LC50 determination of
Calgon JJ-14 (Bardac 22) in marine grass shrimp. 

ACC# 258798:  Fink, R. and Beavers, J. (1982) Eight-day dietary LC50 –
Bobwhite quail: 10-2D: final report: project No. 183-104. Wildlife
International, Ltd. 

ACC# 258798:  Fink, R. and Beavers, J. (1985) Eight-day dietary LC50 –
bobwhite quail: 10-2D: final report: project no. 183-104. Wildlife
International, Ltd.    

ACC# 401298-01:  Henck, J.H. (1986) Avian Eight-day dietary toxicity
test in bobwhite quail. TRL Study No. 014-064. Toxicity Research
Laboratories, Ltd. 

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
Didecyldimethylammoniumchloride (DDAC) in a static acute toxicity test
with mysid shrimp, Mysidopsis bahia. Springborn Laboratories, Inc. 

MRID# 415920-02:  Rhodes, J.E. (2000a) Acute toxicity of P198 to the
bluegill sunfish, Lepomis macrochirus, determined under static
conditions. ABC Laboratories, Inc. 

MRID# 417858-01:  Long, R.D., Hoxter, K.A. and Smith, G.J. (1991a)
Didecyldimethylammoniumchloride: A dietary LC50 study with the northern
bobwhite. Wildlife International, Ltd. 

MRID# 417858-02:  Long, R.D., Hoxter, K.A. and Smith, G.J. (1991b) 
Didecyldimethylammoniumchloride: A dietary LC50 study with the mallard. 
Wildlife International, Ltd.

MRID# 417858-03:  Campbell, S., Hoxter, K.A., and Smith, G.J. (1991)
Didecyldimenthyl ammonium chloride: An acute oral toxicity study with
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MRID# 422538-01:	Cranor, W.  1991.  Aerobic Soil Metabolism of 

[14C]Didecyldimethylammonium chloride (14C-DDAC).  Final Report.  Lab
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Number 37006.  Unpublished study prepared by ABC Laboratories.

MRID# 422538-03:	Cranor, W.  1991.  Aerobic Aquatic Metabolism of 

[14C]Didecyldimethylammonium chloride (14C-DDAC).  Final Report.  Lab
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Number 37008.  Unpublished study prepared by ABC Laboratories.

MRID# 436200-01  Collins, M.K. (1994) Didecyldimethylammoniumchloride
(DDAC): Evaluation in a static acute toxicity test with the sheepshead
minnow (Cyprinodon variegatus). Springborn Laboratories, Inc. 

MRID# 451920-01:  Rhodes, J.E. (2000b) Acute toxicity of P198 to the
rainbow trout, Onchorynchus mykiss, determined under static conditions.
ABC Laboratories, Inc. 

MRID# 458217-01:  England, D.C., and Leak, T. (1995) Chronic toxicity of
sediment-incorporated Didecyldimethylammonium Chloride (DDAC) to
Chironomus tentans. ABC Laboratories, Inc.     

MRID# 458964-01:  Krueger, H.O., Desjardins, D., Kendall, T., and
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MRID# 458964-02:  Krueger, H.O., Desjardins, D., Kendall, T.
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ADDITIONAL REFERENCES:

Bailey, H.C., Elphick, J.R., Potter, A., Chao, E. and Zak, B. (1999)
Acute toxicity of the antisapstain chemicals DDAC and IPBC, alone and in
combination, to rainbow trout (Oncorhynchus mykiss). Water Res. 33(10):
2410-2414.   

Bennett, W.R. and Farrell, A.P. (1998) Acute toxicity testing with
Juvenile white sturgeon (Acipenser transmontanus). Water Qual. Res. Can.
33(1): 95-110.           

Tatarazako, N., Yamamota, K. and Iwasaki, K. (2000) Subacute toxicity of
wood preservatives, DDAC and BAAC, in several aquatic organisms.  J.
Health Sci. 48(4): 359-365.

Teh, S.J., Wong, C., Furtula, V. and Teh, F. (2003) Lethal and sublethal
toxicity of Dedecyldimethylammonoiumchloride in early life stages of
white sturgeon, Acipenser transmontanus. Environ. Toxicol. Chem. 22(9):
2152-2158.

Versar, 2006.  DDAC Modeling (TAF 1-4-17, TAF CM 64).  From Jignasha
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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
biochemistry of rainbow trout (Oncorhynchus mykiss). Can. J. Aquat. Sci.
53:2424-2432.           

                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                       

                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                                                                        
                  

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