MEMORANDUM 

SUBJECT: 

FROM: 

THRU: 

TO: 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

September 13, 2012 

Product Chemistry, Environmental Fate, and Ecological Effects Scoping 

Document in Support of Registration Review of Didecyl dimethyl 

ammonium carbonate (DDA Carbonate) and Didecyl dimethyl ammonium 

bicarbonate (DDA Bicarbonate) 

PC Code: 069208 for Mixture of DP Barcode: 401751 

DDA Carbonate and 

DDA Bicarbonate 

Decision No.: 464738 Registration Nos.: None. 

Petition No(s).: NA Regulatory Action: Ecological 

Environmental Scoping Document for 

Registration Review 

Risk Assessment Type: Multiple Case No.: 5014 

chemical 

TXRNo.:NA CAS Nos.: 

DDA Carbonate: 148788-55-0 

DDA Bicarbonate: 148812-65-1 

MRlD Nos.: See Tables 3 & 4 40 CFR: 180.940(a), Tolerance Exemption 

and pages 4, 7, 8, & 9. 

Srinivas Gowda, M.S. Microbiologist/Science CoordinatorS)!'~·..;~~ 

Donna M. Randall, M.S., Senior Biologist . 

James Breithaupt, M.S. Agronomist Cv~ . /L~ .v L .. ;;/ 

Risk Assessment and Science Support BrJC'h (RASssrv~ Antimicrobials Division (7 51 OP) 

<'A //~ Steven Weiss, Acting Branch Chief ~ VC/.4-

Risk Assessment and Science Support Branch (RASSB) 

Antimicrobials Division (7510P) 

Wanda Henson, Chemical Review Manager 

Regulatory Management Branch II 

Antimicrobials Division (7510P) 

Page 1 of 17 
EXECUTIVE SUMMARY 

Didecyl dimethyl ammonium carbonate (DDACarbonate) and didecyl dimethyl 

ammonium bicarbonate (DDA Bicarbonate) are quaternary ammonium compounds. Bardac® 

22C50 is the trade name for the mixture ofDDA Carbonate and DDA Bicarbonate. Bardac 

22C50 is registered for use in the formulation of wood preservatives, sapstain control, hardsurface disinfectants, nonfood contact surface sanitizers, food contact surface sanitizers, oilfield 

biocide and as a material preservative (metal working fluids, paints, household and industrial, 

cleaning and related products packaged in aerosol cans). Bardac® 22C50 is not for use in 

marine and estuarine oil fields. In water DDA Carbonate and DDA Bicarbonate dissociate into 

DDA cations and carbonate/bicarbonate anions. For the registered use patterns the exposure 

pathway of concern is the aquatic environment and the Agency is conducting its fate and 

environmental assessment on the DDA cation. 

The environmental fate of didecyl dimethyl ammonium carbonates (DDA carbonatesincludes both carbonate and bicarbonate) is essentially the same as didecyl dimethyl ammonium 

chloride (DDAC, PC Code 069149), and therefore the data for DDAC were used to bridge to and 

help satisfy DDA carbonates environmental fate data requirements. DDA carbonates will 

disassociate upon contact with water to form the DDA cation and the carbonate/bicarbonate 

anions, and the cation will sorb nearly irreversibly to soil and sediment because of the negative 

charge associated with soil and sediment. Based on DDAC studies, the DDA cation is expected 

to be stable to hydrolysis and photodegradation in water and essentially stable to aquatic 

metabolism. However, DDA in activated sludge was found to be readily biodegradable. Except 

for an oyster bioconcentration study for DDA, all fate data needed to conduct an ecological risk 

assessment for DDA carbonate uses resulting in discharge of waste water from treatment plants 

are fulfilled. 

The DDA carbonates ecological risk assessment will be based on studies using Bardac 

22C50 as the test chemical and when not available, data on DDAC as the test chemical will be 

used. DDAC is similar to Bardac 22C50 and was determined to be acceptable as a surrogate 

compound after an extensive review of the two compounds' chemical and toxicological 

properties. Several Acceptable ecological studies were available in the OPP Agency files from 

past registrations. These included bird studies, both dietary and acute, acute freshwater fish and 

freshwater invertebrate toxicity studies, acute toxicity studies to estuarine/marine fish, acute 

toxicity studies to estuarine/marine invertebrates, a chronic toxicity fish early-life stage study, a 

chronic freshwater invertebrate study, acute toxicity studies, both freshwater and estuarine, of 

treated sediment to invertebrates, toxicity studies to Alga and Lemna gibba. All of these studies 

will be available for an ecological risk assessment. A honey bee acute contact study, toxicity of 

residues to honeybees, and an activated sludge respiration inhibition study is needed for DDA. 

An ecological risk assessment will be conducted for those premise and equipment uses, 

industrial process and water systems, material preservative uses and wood preservative uses 

resulting in discharge to waste treatment facilities with releases to surface water. The risk 

assessment will also include an assessment of direct and indirect effects to listed (i.e., 

endangered and threatened) species. If the assessment concludes that this use "may affect" a 

Page 2 of 17 
listed species or its designated critical habitat, the Agency will consult with the U.S. Fish and 

Wildlife Service and/or National Marine Fisheries Service (the Services), as appropriate 

INTRODUCTION 

Didecyl dimethyl ammonium carbonate (DDA Carbonate) and didecyl dimethyl 

ammonium bicarbonate (DDA Bicarbonate) are quaternary ammonium compounds. The didecyl 

dimethyl ammonium carbonates (DDA carbonates-includes both carbonate and bicarbonate) 

were first registered with EPA on May 15, 1995 for use as a hard non-porous surface disinfectant 

and a material preservative. Currently eleven products (1 technical and 10 end-use) are 

registered for the uses in the formulation of wood preservatives, sapstain control, hard-surface 

disinfectants/sanitizers, food contact surface sanitizers, oilfield biocides and as a material 

preservative (metal working fluids, paints, household and industrial, cleaning and related 

products packaged in aerosol cans). A detailed list of use patterns and use sites of the DDA 

carbonates are listed below. The products have declared DDA carbonates content of 7.5% to 

50%. 

Antimicrobial Use Sites 

Food Handling/storage establishments premises and equipment 

Beer fermentation and storage tanks 

Dairy processing equipment 

Egg washing treatments 

Entryway sanitizing systems 

Food processing equipment, Conveyors 

Hard non-porous surfaces in restaurants 

Sanitary filling equipment, ice machines, soft serve and frozen beverage dispensing 

equipment 

Waterproof gloves, shoe baths 

Industrial processes and water systems 

Gas/oil recovery systems 

Hydrotesting pipelines or vessels 

Pipeline pigging and scraping operations 

Materials Preservatives 

Aerosol cans, petroleum products, cleaning products, and cleaning, sanitizing, and 

disinfecting wipes for use on hard non-porous, surfaces 

Paints and decorative coatings 

Metalworking fluids 

Paper and Paperboard 

Metalworking Cutting Fluids 

Medical premises and equipment 

Hard non-porous surfaces in hospitals, nursing homes and dentist offices, etc. 

Salon I barber tools and instruments 

Page 3 of 17 
Ultrasound transducers, probes, mammography compressor plates 

Residential and public access premises 

Air freshener 

Hard non-porous surfaces in household/domestic dwellings 

Laundry 

Holding tanks, gray water tanks. 

Wood Preservatives 

Pressure treatment 

Except for statements of the DDA carbonates content as total DDA content, all product 

chemistry data requirements have been satisfied. 

A Reregistration Eligibility Decision (RED) has not been issued by the Agency for DDA 

Carbonate and DDA Bicarbonate because the initial registration date was after the November 

1984, federal mandated cutoff for initiation of the RED process. An ecological risk assessment1 

was conducted in 2007 for registration of DDA carbonates treated wood in aquatic environments. 

Risks to terrestrial wildlife were not calculated because information on leaching to soil and lack 

of reliable exposure estimates. Risks to terrestrial plants were not calculated due to lack of plant 

effects data for DDA carbonates and DDAC. Chronic aquatic risks could not be calculated 

either, due to the lack of chronic fish and invertebrate data. The acute level of concern was 

exceeded for endangered aquatic invertebrates but there was no exceedance for fish. 

Mode of Action 

Like other quarternary ammonium compounds DDA is a membrane-active agent, causing 

leakage of intracellular molecules leading to death. 

A. Product Chemistry Summary of Bardac® 22C50- Mixture of DDA Carbonate and DDA 

Bicarbonate 

Chemical identity and the physical and chemical properties of DDA carbonates are provided 

in Tables 1 and 2. The primary source of information for this assessment was MRID numbers 

43685701, 45524302, and 45524303. Except for a declaration of the total DDA content, all 

product chemistry data requirements have been satisfied for the DDA Carbonate and DDA 

Bicarbonate mixture. 

1 RASSB Norm Cook memorandum to Velma Noble, June 20, 2007, Carboquat (Bardac 22C50) Environmental 

Monitoring Study- Dock Wood Treatment Review and Revised Ecological Risk Assessment. D332891, 332720, 

332892, 332909, 332905. PC code: 069208. 

Page 4 of 17 
Table 1. Chemical Identity 

Mixture of DDACarbonate/DDABicarbonate- SO% 

Mixture of: 

Chemical Name N-decyl-N,N-dimethyl-1-decanaminium carbonate and 

N -decyl-N ,N -dimethyl-1-decanaminium bicarbonate 

Mixture of: 

Common Name Didecyl dimethyl ammonium carbonate and 

Didecyl dimethyl ammonium bicarbonate 

Synonyms N -,N-Dialkyl-N ,N -dime thy lammonium bicarbonate/carbonate 

Trade Names Bardac® 22C50 

Classification Quaternary Ammonium Compound (QAC) 

PC Code 069208 

Mixture: 

CAS Nos. DDA Carbonate -148788-55-0 and 

DDA Bicarbonate- 148812-65-1 

Mixture: 

Molecular Formula DDA Carbonate - [C2 ~sNh C03 

DDA Bicarbonate- [C ~N] 1 HC03 

Mixture: 

Molecular Weight DDA Carbonate - C4sH96N203 -713.2597 g/mol 

DDA Bicarbonate- C23~9N03 - 387.6424 g/mol 

{ ~tl l t 

HCOf 

~~"\ I 

Molecular Structure: 

{ ~,< / } : CO:J.Z 

T a bl e 2 P d . ro uc t Ch em1s • t ry D a a t S ummaryo fDDAC ar b ona t e /DDAB. 1car b ona t e (SO~) 0 

Guideline Physical and Chemical Mixture of DDA Carbonate/DDA Bicarbonate (SO%) Number Properties 

830.1550 Product identity and composition Refer to Table 1. 

830.1800 Enforcement analytical method HPLC 

830.6302 Color Clear yellow liquid. Colorless to pale yellow liquid. 

830.6303 Physical State Liquid concentrate 

830.6304 Odor Faint alcoholic amine odor 

Stability to sunlight, normal and Stable to elevated temperature, metals and sunlight. 830.6313 elevated temperature, 1 yr storage stability: Stable metals/metal ions 

830.7000 pH 10.46 to 10.80 at 10% active in aqueous solution at 25°C. 

830.7050 UV Nisible Absorption Not expected to absorb at A. >300 nm 

830.7100 Viscosity 63- 129 eSt at 25°C 

830.7200 Melting point Not reg_uired. 

Page 5 of 17 
Guideline Physical and Chemical Mixture of DDA Carbonate/DDA Bicarbonate (50%) Number Properties 

830.7220 Boiling point Not required. Similar to water 

830.7300 Density 0.962 at 25°C 

Not applicable because the chemical structure has no 

830.7370 Dissociation Constant dissociable groups other than the ion pairs shown in the 

molecular structure provided in Table 1. 

830.7550 Partition coefficient (n- Not required-Ionic compound. octanoVwater) 

830.7840 Solubility in water 100% Soluble 

830.7860 Solubility in organic solvents Bardac® 22C50 is freely soluble in water, lower alcohols, 

octanol, ketones and gly_cols. 

830.7950 Vapor pressure Not required-Ionic compound. 

B. Environmental Fate Summary 

The environmental fate of didecyl dimethyl ammonium carbonates (DDA carbonatesincludes both carbonate and bicarbonate) is essentially the same as didecyl dimethyl ammonium 

chloride (DDAC, PC Code 069149), and therefore the data for DDAC were used to bridge to and 

help satisfy DDA carbonates environmental fate data requirements. DDA carbonates will 

disassociate upon contact with water to form the DDA cation and the carbonate/bicarbonate 

anions. Like DDAC, DDA Bicarbonate releases one mole of DDA cations, however, DDA 

Carbonate releases two moles of DDA cations. The DDA cation will sorb nearly irreversibly to 

soil and sediment because of the negative charge associated with soil and sediment. Based on 

DDAC studies, the DDA cation is expected to be stable to hydrolysis and photodegradation in 

water and essentially stable to aquatic metabolism. However, DDA was found to be 

biodegradable in the Ready Biodegradability study. Except for an oyster bioconcentration study 

for DDA, all fate data needed to conduct an ecological risk assessment for DDA carbonate uses 

resulting in discharge to waste water treatment plants are fulfilled. 

Abiotic Fate 

Nonionized/Ionized Ratio and pH 

The product chemistry data indicate that DDA Carbonate and Bicarbonate will 

disassociate immediately upon contact with water. DDA Bicarbonate releases one mole of DDA 

cations per mole; however, DDA Carbonate releases two moles of DDA cations per mole. The 

carbonate/bicarbonate ion equilibrium will depend on the pH of the solution. Formation of 

bicarbonate ion (HC03 1-) from carbonic acid (HzC03) in water occurs with a pKa (disassociation 

constant) of 6.4, while carbonate (C03

2

") formation from bicarbonate occurs with a pKa of at 

10.3 at 25 °C2

. As a result, the equilibrium between bicarbonate and carbonate will favor the 

presence of bicarbonate in the range of most environmental pH values of 5-7. 

2 http://en. wikipedia.org/wiki/Carbonic_acid 

Page 6 of 17 
Hydrolysis and Photolysis 

DDA has been shown using DDAC to be hydrolytically stable under abiotic and buffered 

conditions over the pH 5-9 range (MRID 41175801). DDA is stable to photodegradation in pH 7 

buffered aqueous solutions; even in the presence of a photosensitizer (acetone), degradation is 

minimal (MRID 41175802). DDA is not subject to photodegradation in soil (MRID 42480701). 

Adsorption/Desorption 

DDA is immobile in soil. A soil mobility study using DDAC reviewed by the Agency 

shows that DDA has a strong tendency to bind to sediment/soil with Freundlich Kads values of 

1,095, 8,179, 32,791, and 30,851 in sand, sandy loam, silty clay loam, and silt loam soils, 

respectively. Because of its strong adsorption to soils, DDA in aquatic systems is expected to 

partition to suspended particulates and sediment and is not expected to contaminate ground 

waters (MRID 41385301). 

Wood leaching 

Information on the aqueous availability of DDA from DDAC treated wood indicates that 

the use of DDAC as a wood preservative may result in minimal DDA releases to the 

environment (MRID 45524305). 

Biotic Fate 

DDA is expected to degrade with half-lives of 9-13 days in hybrid sewage studies 

without clay and 45 days with added clay. The registrant submitted an OECD carbon and 

nitrogen transformation test, which demonstrated a lack of effects on glucose metabolism and an 

increase in ammonia formation with complex and clay rate, but no increase in nitrate formation. 

Because of its electric charge and cell membrane activity, the DDA cation is not expected to 

bioconcentrate in fish. 

Aquatic Aerobic and Anaerobic Metabolism 

Aquatic metabolism studies under aerobic and anaerobic conditions indicate that DDAC 

is stable to microbial degradation under STANDARD SUBDIVISION N tests. The calculated 

aerobic and anaerobic half-lives of Carbon 14-labeled DDAC e4

C-DDA chloride) in flooded 

river water are 180 days and 261 days, respectively (MRIDs 42253802 and 42253803). 

Similarly, DDAC was found to be stable with very little degradation in aerobic soils during a 

year-long metabolism study (MRID 42253801). However, in tests that were hybrids of different 

guidelines (MRIDs 4755512,-15, -17), DDAC that is not complexed with clay is considered to 

be readily biodegradable. On the other hand, tests using DDAC:Clay complexes demonstrated 

that sorption to clay prevented ready biodegradation. As a result, any DDAC that reaches 

bottom sediment would be likely to be more persistent than the DDAC in the water column. 

In an acceptable aerobic aquatic biodegradation in a shake flask study (OCSPP 

835.3100, MRID 47522212), the half-lives in a loam soil (5.6% organic matter) ranged from 10-

Page 7 of 17 
12 days, with an upper lOth confidence bound (CB) of the mean of 13 days. This study is 

intended to simulate ready biodegradability in the aquatic environment. In this study, DDAC 

was shown to be readily biodegradable with -80 % of theoretical C02 (ThC02) formed in 28 

days. 

In an acceptable ready biodegradability study using the headspace method (OECD 

301B/40 CFR 796.3260, Modified Sturm Test), the persistence of DDAC in an un-inoculated 

river water/sediment system was studied (MRID 47522217). The half-lives were 11 and 45 days 

in a non-clay and clay (one part DDAC and 10 parts clay) system, respectively. Under the 

conditions of this study, DDAC-treated systems without clay achieved the required threshold 

value of 70% ThC02 evolution between 10 % degradation and 28 days of study ( 17-20 days 

observed). However, DDAC:clay complex-treated systems did not achieve the required 

threshold value of 70% ThC02 by within 28 days or the study length (55 days). These results 

are expected given the strong tendency of DDAC to sorb to clay and organic material. Ninety 

(90) and 52% of the theoretical C02 (ThC02) evolved from the system. 

In a hybrid aerobic aquatic metabolism/Ready Biodegradability test (OCSPP 

835.3100/0ECD 301B), the registrant used clay, centrifuging, and acclimation of inoculum 

(MRID 47522215). The first part of the study involved centrifuging of clay in systems that were 

either acclimated or not acclimated. The observed half-lives were about 12 days for each test, 

indicating that centrifuging the clay was the main factor. Twenty-seven percent of ThC02 from 

acclimated and non-acclimated samples evolved from the system. The second test involved nonacclimated samples with no centrifugation. The half-life was about 9 days. The DDAC:clay 

complex-treated systems did not achieve the required threshold value of 70% ThC02 evolution. 

However, the reference control (sodium benzoate) systems achieved the threshold value by 7 

days posttreatment (%ThC02 evolved was 68-79 %), indicating the inoculum was viable and the 

test was valid. 

Biodegradability in Activated Sludge and Activated Sludge Inhibition 

One guideline study for biodegradation in activated sludge was submitted (MRID 

4755514). In this OECD 301A (dissolved organic carbon die-away) study, the half-lives of 

DDAC in acclimated sewage sludge were 6 and 8 days, with an upper lOth CB on mean of 11 

days. The sludge concentrations were 5 and 10 mg carbon!L. Bardac 22 was considered to be 

readily biodegradable since 79 and 73 % (>70 %) removal of dissolved organic carbon (DOC) 

was observed in the 10-day window for the 5 and 10 mg Carbon/1 (MRID 47522214). 

In a Ready Biodegradability test (OECD 301A, dissolved organic carbon die-away), the 

half-lives of DDA chloride in acclimated sewage sludge were 6 and 8 days, with an upper lOth 

CB on mean of 11 days (MRID 47522214). The sludge concentrations were 5 and 10 mg 

carbon/L. Bardac 22 was considered to be readily biodegradable since 79 and 73% (>70 %) 

removal of DOC was observed in the 10-day window for the 5 and 10 mg C/1. 

The registrant submitted an OECD carbon and nitrogen transformation test, which 

represents heterotrophic bacteria in sediments. There were no effects on glucose metabolism at 

Page 8 of 17 
1, 3, and 10% complex of DDAC:clay. However, there was some increase in ammonia 

formation with complex and clay rate, but no increase in nitrate formation (MRID 47522213). 

These results that the DDAC:clay complex did not affect the viability of aerobic and facultative 

bacteria in the sediment. These bacteria are important for the function of metabolizing carbon in 

sediments. The nitrogen results indicate that nitrifying bacteria were not active in the tested 

sediment, so no conclusions related to the DDAC:clay complex could be made. 

Bioconcentration 

DDA is not expected to pose a concern for bioconcentration in non-filter feeding aquatic 

organisms. In a fish bioconcentration study (MRID 45834101) mean steady state 

bioconcentration factors for DDA were determined to be 38, 140, and 81 in the edible, nonedible, and whole body fish tissue, respectively. Given that DDA is expected to have a high 

affinity to sorbing to organic and inorganic particulate matter there is a potential for filterfeeding organisms to uptake DDA sorbed to their food. A bioconcentration study using a filter 

feeding organism such as a mollusk is needed to address risk from this exposure pathway. 

Drinking Water 

Based on the fate characteristics of DDA, it is not expected to contaminate drinking water 

surface or groundwater sources. DDA reaching surface waters are expected to be associated 

with particulate matter and sediment. Additionally any particulate matter would be removed 

during water treatment. 

Water Quality 

DDA and DDA carbonates are not identified as a cause of impairment for any water 

bodies listed as impaired under section 303(d) of the Clean Water Act, based on information 

provided at the Agency's National Pesticides Cause of Impairment of Waters website (searched 

July 11, 2012)3

. In addition, no Total Maximum Daily Loads (TMDL) have been developed for 

DDA Carbonate/DDA Bicarbonate, based on information provided at the Agency's National 

Pesticide TMDL web site (searched July 11, 2012)4

• More information on impaired water bodies 

and TMDLs can be found at http://www.epa.gov/owow/tmdl/. The Agency invites submission 

of water quality data for this pesticide. To the extent possible, data should conform to the quality 

standards in Appendix A of the OPP Standard Operating Procedure: Inclusion of Impaired 

Water Body and Other Water Quality Data in OPP's Registration Review Risk Assessment and 

Management Process (see: http://www .epa. gov /oppfead llcb/ppdc/2006/november06/session 1-

sop.pdf ), in order to ensure they can be used quantitatively or qualitatively in pesticide risk 

assessments. 

Table 3. Environmental Fate Results and Status of Data Requirements 

3 . http://iaspub.epa.gov/tmdl waters!O/attains nation cy.cause detail 303d?p cause group id=885 4 

http://iaspub.epa.gov/tmdl waters 10/attains nation.tmdl pollutant detail?p pollutant group id=885&p pollutant 

group name=PESTICIDES 

Page 9 of 17 
Test Guideline Guideline Result Comments/ Status of Data 

No. References Requirement 

Hydrolysis 161-1 Stable at pH 5, 7, and 9 MRID 41175801 Satisfied 

Photodegradation Stable in non-sensitized 

161-2 and sensitized buffer MRID 41175802 Satisfied in water solutions 

Photodegradation 161-3 Stable MRID 42480701 Satisfied 

on soil 

Aerobic soil 162-1 Stable MRID 42253801 Satisfied 

Anaerobic aquatic 162-3 261 days MRID 42253802 Satisfied metabolism 835.4300 

Aerobic aquatic 162-4 metabolism (soil OCSPP 835.4400 180 days MRID 42253803 Satisfied 

and water only) 

10-12 days (upper 10m CB 

on mean of 13 days) 

Aerobic aquatic 40 CFR 796.3100 metabolism in This is assumed Readily biodegradable MRID 47522212 Satisfied surface water and 

to be 835.3100 ThC02 evolution did not 

sediment reach 70 % by 10 days .. 

but did reach 80 % by 28 

days (end of study) 

River water Half-lives of 11 and 45 

system days in non-clay and clay 

(uninoculated) systems, respectively. 

No clay >70% ThC02 evolution 

MRID 47522217 OECD301B within 14-17 days for 

40 CFR 796.3260 DDAC only (readily Modified Sturm Satisfied 

biodegradable) Test 

Clay <70 % ThC02 evolution 

from DDAC:clay system 

(not readily 

biodegradable) 

Ready 

Half-lives of 6 and 8 days 

(upper lOth CB on mean 

Biodegradability of 11 days) 

test using 

activated sludge OECD301A 79 and 73 % removal of MRID 47522214 Satisfied 

Dissolved organic DOC in 10 days for 

carbon die-away DDAC only system with 

test 5 and 10 mg C/L (Readily 

biodegradable) 

Page 10 of 17 
Guideline Comments/ Status of Data Test Guideline Result No. References R~uirement 

Centrifuged samples 

Half-lives of about 12 

days for both nonacclimated and acclimated 

Aerobic aquatic 

OCSPP 835.3100 Non-centrifuged MRID 47522215 Satisfied metabolism (clay, 

centrifuging, and OECD301B Half-life of about 9 days 

inoculation) 

70 % ThC02 "pass" level 

for ready biodegradability 

was not reached 

No effect of DDAC and 

clay complex on 

heterotrophic bacteria in 

sediments 

No effect on glucose 

metabolism at 1, 3, and 10 

%complex of OECD carbon and This is not a data OECD 217 and DDAC:clay. nitrogen MRID 47522213 requirement for 216 transformation test this assessment. General increase in 

ammonia formation with 

complex and clay rate 

Nitrogen transformation 

portion of test is not 

applicable because soil 

had no nitrifying bacteria 

Freundlich Kads values of Satisfied 

1,095, 8,179, 32,791, and Aged leaching Leaching- 30,851 in sand, sandy MRID 41385301 not required adsorption- 163-1 loam, silty clay loam, and because of desorption silt loam soils, DDAC stability 

re~ective_!y. in unaltered soils 

Bioconcentration factors B ioconcentration 165-4 of 38X, 140X, and 81X in in fish MRID 45834101 Satisfied OCSPP 850.1730 the edible, non-edible, and 

whole body fish tissues. 

Leaching from Minimal leaching from treated wood Ell-97 MRID 45524305 Satisfied treated wood 

Page 11 of 17 
C. Ecological Effects Summary 

Available ecotoxicity guideline studies and the results are summarized in Tables 4 and 5 

for terrestrial and aquatic animals, respectively. Except for an activated sludge inhibition study, 

an acute dermal contact honey bee study, and the oyster bioconcentration study discussed in the 

fate section, no additional effects data are anticipated to perform the ecological risk assessment. 

Toxicity to Terrestrial Organisms 

A summary of the available toxicity data endpoints from registrant-submitted studies is 

provided in Table 4, data from DDAC was also used. The ecotoxicity endpoint values in the 

table are currently expressed as the active ingredients (a.i.s) either DDAC or as the DDA 

carbonates. To adjust for differences in molecular weight and the presence of two moles of 

DDA for every one mole of DDA Carbonate as compared to DDAC and DDA Bicarbonate, all 

the values in the table will be expressed as DDA for the risk assessment. DDA is practically 

nontoxic to birds on a dietary basis but is moderately on an acute oral basis. Insect pollinator 

data are required based on DDA carbonate wood preservative uses. Mammalian toxicity data for 

evaluating exposure of mammalian wildlife is available for acute oral toxicity and is discussed in 

the human health scoping document. 

Table 4: Ecological Effects Data Summary of DDA Carbonate/DDA Bicarbonate and 

DDAC for Terrestrial Organisms 

OPPTS Study/Species Study Results Guideline Chemical (expressed as a.i.)1 Comments 

No. MRID Number/ACC# 

850.2100 Acute Oral LDso LDso = 95 mg ailkg Acceptable 

Bobwhite Quail NOAEL <31.2 mg ailkg 

Bardac 22C50 Moderately toxic 

43685702 

850.2100 Acute Oral LDso LD50 = 217 mg ailkg Acceptable 

Bobwhite Quail NOAEL = <31 mg ailkg 

DDAC Moderately toxic 

41785803 

850.2100 Acute Oral LDso LD50 = 54.4 mg ailkg Acceptable 

Bobwhite Quail NOAEL=<39 

DDAC Moderately toxic 

258798 

850.2200 Eight-Day Dietary LCso LCso = >5620 ppm ai Acceptable/ 

Bobwhite Quail NOAEC = 1780 ppm ai 

Bardac 22C50 Practically non-toxic 

43707101 

850.2200 Eight-Day Dietary LCso LC50 = >5620 ppm ai Acceptable 

Mallard Duck NOAEC = 1000 ppm ai 

Bardac 22C50 Practically non-toxic 

43649106 

Page 12 of 17 
OPPTS Study/Species Study Results Guideline Chemical (expressed as a.i.i Comments 

No. MRID Number/ACC# 

850.2200 Eight-Day Dietary LC50 = >5620 ppm ai Acceptable 

LCso NOAEC = 562 ppm ai 

Mallard Duck Practically non-toxic 

DDAC 

41785802 

850.2200 Eight-Day Dietary LCso LCso = >5620 ppm ai Acceptable 

Bobwhite Quail NOAEC = 1780 ppm ai 

DDAC Practically non-toxic 

41785801 

850.2200 Eight-Day Dietary LC50 LCso = >5620 ppm ai Acceptable 

Bobwhite Quail NOAEC = 3180 ppm 

DDAC Practically non-toxic 

258798 

850.2200 Eight-Day Dietary LCso LCso = >5620 ppm ai Acceptable 

Mallard Duck NOAEC = 1780 

DDAC Practically non-toxic 

258798 

1· .. Toxicity values currently expressed as active mgredient DDAC and DDA carbonates will be 

converted to DDA for use in the risk assessment. 

Toxicity to Aquatic Organisms 

A summary of acute and chronic aquatic ecotoxicity data endpoints from registrantsubmitted studies for DDA carbonates and for DDAC is provided in Table 5. To adjust for 

differences in molecular weight and the presence of two moles of DDA for every one mole of 

DDA Carbonate as compared to DDAC and DDA Bicarbonate, all the values in the table will be 

expressed as DDA for the risk assessment. DDACand DDA carbonates appear moderately 

acutely toxic to highly toxic to fish but very highly toxic to aquatic invertebrates 

Table 5: Ecological Effects Data Summary of DDA Carbonate/DDA Bicarbonate and 

DDAC for Aquatic Organisms 

OPPTS Study/Species Study results Guideline Chemical (expressed as a.i.)1 Comments 

No. MRID Number/ACC# 

850.1075 Acute Toxicity to Rainbow 96-hour LC50 = 803 Acceptable 

Trout ppb ai 

Bardac 22C50 NOAEC = 580 ppm 

43649108 Highly toxic 

850.1075 Acute Toxicity to Bluegill 96-hour LC50 = 270 ppb ai Acceptable 

Sunfish NOAEC = 98 ppb ai 

Bardac 22C50 Highly toxic 

43649107 

Page 13 of 17 
OPPTS Study/Species Study results Guideline Chemical (expressed as a.i.i Comments 

No. MRID Number/ACC# 

850.1075 Acute Toxicity to Bluegill 96-hour LC50 = 600 ppb ai Acceptable 

Sunfish Highly toxic 

DDAC 

256571 

850.1075 Acute Toxicity to Rainbow 96-hour LC50 = 2800 ppb ai Acceptable 

Trout Moderately toxic 

DDAC 

256571 

850.1075 Acute Toxicity to Bluegill 96-hour LC50 = 270 ppb ai Acceptable 

Sunfish Highly toxic 

DDAC 

007958 

850.1075 Acute Toxicity to Rainbow 96-hour LC50 = 1100 ppb ai Acceptable 

Trout Moderately toxic 

DDAC 

007958 

850.1075 Acute Toxicity to Bluegill 96-hour LC50 = 320 ppb ai Acceptable 

Sunfish NOAEC=<100 

DDAC Highly toxic 

41578001 

850.1075 Acute Toxicity to Rainbow 96-hour LC50 = 1000 ppb ai Acceptable 

Trout NOAEC = 590 ppb ai 

DDAC Moderately toxic 

41578003 

850.1400 Freshwater Fish chronic toxicity: Length, dry wt, wet wt: Acceptable 

Fathead minnow in fish early- NOAEC = 18 ug/L (supplemental) 

life stage LOAEC = 32 ug/L 

Bardac 22C50 Survival: 

46362301 NOAEC = 86 ug/L 

LOAEC = 170 ug/L 

Hatching success: 

NOAEC = > 170 ug/L 

LOAEC = > 170 ug/L 

850.1010 Acute Toxicity to Water Flea EC50 = 66 ug/L Acceptable 

(Daphnia magna) NOAEL = 33 ug/L 

Bardac 22C50 Very highly toxic 

43649109 

850.1010 Acute Toxicity to Water Flea ECso = 18 ug/L Acceptable 

(Daphnia magna) NOAEC = < 5.6 ug/L 

DDAC Very highly toxic 

225596 

850.1010 Acute Toxicity to Water Flea EC50 = 94 ug/L Acceptable 

(Daphnia magna) NOAEC = 74 ug/L 

DDAC Very highly toxic 

41578002 

Page 14 of 17 
OPPTS Study/Species Study results Guideline Chemical (expressed as a.i.i Comments 

No. MRID Number/ACC# 

850.1300 Chronic Freshwater 21 day Length and dry wts: Acceptable 

invertebrate study (Daphnia NOAEC = 27 ug ai/L 

magna) LOAEC = 46 ug ai/L 

Bardac 22C50 Adult Mortality: 

46295805 NOAEC = 46 ug ai/L 

LOAEC = 77 ug ai/L 

Reproductive success: 

NOAEC = > 77 ug ai/L 

LOAEC = 77 ug ai/L 

850.1075 Acute Toxicity Test using LCso = 1100 ug/L Acceptable 

Sheepshead minnow NOAEC = 890 ug/L 

( Cyprinodon variegates) Moderately toxic 

Bardac 22C50 

43649110 

850.1075 Acute Toxicity Test using LCso = 960 ug/L Acceptable 

Sheepshead minnow NOAEC = 390 ug/L 

(Cyprinodon variegates) Highly toxic 

DDAC 

43620001 

850.1025 Acute Toxicity test using ECso = 82 ug/L Supplemental 

Estuarine/Marine invertebrates: NOAEC = 25 ug/L 

Eastern oyster ( Crassostrea Very highly toxic 

virginica) 

Bardac 22C50 

43649112 

850.1025 Acute Toxicity Test using EC50 = 94 ug/L Acceptable 

Estuarine/Marine invertebrates: NOAEC = 63 ug/L 

Eastern Oyster ( Crassostrea Very highly toxic 

virginica) 

DDAC 

43260003 

850.1025 Acute Toxicity Test using ECso = 6400 ug/L Acceptable 

Estuarine/Marine invertebrates: NOAEC = 90 ug/L 

Eastern Oyster ( Crassostrea Moderately toxic 

virginica) 

DDAC 

249002 

850.1735 Acute Toxicity of treated 14 day emergence: Supplemental 

sediment to Freshwater Midge ECso = 1438 mg/Kg 

(Chironomus tentans) Growth emergence: 

DDAC NOAEC = 530 mg/Kg 

45821701 28 day emergence: 

ECso = 1981 mg/Kg 

NOAEC = 260 mg/Kg 

Page 15 of 17 
OPPTS Study/Species Study results Guideline Chemical (expressed as a.i.)1 Comments 

No. MRID Number/ACC# 

850.1735 Acute Toxicity of treated 10 day survival: Acceptable 

sediment to Freshwater Midge EC50 = 1254 mg/Kg 

( Chironomus tentans) 10 day growth: 

Bardac 22C50 EC50 = 1063 mg/Kg 

46375402 Growth and survival: 

NOAEC = 250 mg/Kg 

LOAEC = 500 mg/I(g 

850.1740 Acute Toxicity of treated 10 day % survival: Supplemental 

sediment to Estuarine Amphipod EC5o = 24.1 mg ai/Kg 

(Leptocheirus plumulosus) NOAEC = 13 mg ai/Kg 

Bardac 22C50 LOAEC = 25 mg ai/Kg 

46375403 

850.4225 Seedling emergence and ECz5 =55.4 mg ai/Kg (dry wt) Supplemental 

850.4250 vegetative vigor using Rice NOAEC = 39.1 mg ai/Kg 

(Oryza sativa) 

Carboquat WP 

46375401 

850.5400 Toxicity to Green algae EC50 = 26 ug ai/L Acceptable 

(Selenastrum capricornutum) NOAEC = 14 ug ai/L 

Bardac 22C50 

45896402 

850.5400 Toxicity to Blue-green EC50 =58 ug ai/L Acceptable 

cyanobacteria (Anabaena NOAEC = 40 ug ai/L 

flosaquae) 

Bardac 22C50 

46295801 

850.5400 Toxicity to Freshwater Diatom EC50 = 11.3 ug ai!L Acceptable 

(Navicula pelliculosa) NOAEC = 5.4 ug ai/L 

Bardac 22C50 

46295803 

850.5400 Toxicity to marine Diatom EC5o = 25 ug ai/L Acceptable 

(Skeletonema costatum) NOAEC = 20 ug ai/L 

Bardac 22C50 

46295804 

850.4400 Toxicity to Floating macrophyte ECso = 118.8 ug ai/L Acceptable 

(Lemna gibba) NOAEC = 9.1 mg 

Bardac 22C50 

46295802 

Environmental Fate and Ecotoxicity Data Gaps and Anticipated Work 

The Agency plans on performing an ecological risk assessment for those premise and 

equipment uses, industrial process and water systems, material preservative uses and wood 

preservative uses resulting in discharge (such as down the drain disposal of used cleaning and 

disinfecting solutions, laundry water, etc.) to waste treatment facilities with subsequent releases 

Page 16 of 17 
to surface water. The ecological risk assessment planned during registration review will allow 

the Agency to make a "no effect" or "may affect" determination for federally listed threatened or 

endangered species (listed species) and their designed critical habitats. When an assessment 

concludes that a pesticide's use "may affect" a listed species or its designated critical habitat, the 

Agency will consult with the U.S. Fish and Wildlife Service and/or National Marine Fisheries 

Services (the Services), as appropriate. 

Environmental Fate Data Gaps 

Except for the oyster bioconcentration study which is also an ecological effects study, 

there are no environmental fate data gaps. 

Ecotoxicity Data Gaps 

The Agency anticipates needing the following ecotoxicity data in order to conduct a 

complete ecological risk assessment, including an endangered species assessment: 

• Oyster bioconcentration study (OCSPP 850.1730); 

• Honey bee acute contact study (OCSPP 850.3020); 

• Toxicity of residues to honeybees (OCSPP 850.3030); and 

• Activated Sludge Respiration Inhibition (OCSPP 850.3300 or OECD 209). 

Other Data Gaps 

For estimating environmental exposure concentrations in the aquatic environment, the 

Agency anticipates needing production volume data for the uses as input in down-the-drain 

models, and industrial and material preservative emission scenario models. 

Page 17 of 17