New York State Department of Environmental Conservation...

Alexander B. Grannis

Commissioner

New York State Department of Environmental ConservationDivision of Solid & Hazardous MaterialsBureau of Pesticides Management625 Broadway, Albany, New York 12233-7257Phone: 518-402-8788 FAX: 518-402-9024Website: http://www.dec.ny.govE-Mail: [email protected]

October 31, 2007

CERTIFIED MAILRETURN RECEIPT REQUESTED

Mr. Eliot HarrisonAgent for Lonza, Inc. Lewis & Harrison, LLC122 C Street, NW Suite 740Washington, DC 20001

Dear Mr. Harrison:

Re: Registration of the New Pesticide Product Carboquat WP-50 (EPA Reg. No.6836-304) Containing the Active Ingredients didecyl dimethyl ammoniumcarbonate and didecyl dimethyl ammonium bicarbonate (Chemical Code 069208)

The New York State Department of Environmental Conservation (Department) has reviewed theapplication and data package, received June 7, 2004, with additional information submitted by Lewis &Harrison on behalf of their client, Lonza, Inc., to register the pesticide product Carboquat WP-50 (EPAReg. No. 6836-304) in New York State. Carboquat WP-50 contains the active ingredients didecyldimethyl ammonium carbonate and didecyl dimethyl ammonium bicarbonate (together identified asDDACarb). This pesticide product is currently registered in New York State as a manufacturing useproduct (named Carboquat 150T) intended for repackaging or formulation of wood preservativeproducts only. The revised label makes Carboquat WP-50 a “repack” of Carboquat 150T for endproduct use. This additional proposed use of didecyl dimethyl ammonium carbonate and didecyldimethyl ammonium bicarbonate represents a major change in labeled use pattern for these activeingredients in New York State.

The New York State Department of Health (DOH), the Department’s groundwater staff, and theDepartment’s Bureau of Habitat (BOH) have reviewed the information submitted to date in support ofthe application for registration of Carboquat WP-50 (EPA Reg. No. 6836-304).

Environmental Fate Risk Assessment:

Carboquat WP-50 contains 50% active ingredient, or 7.7 lb ai/gallon, for use as a woodpreservative. The product is mixed to a 0.6 to 3.9% solution and applied to the wood and placed in apressure cylinder and treated. The maximum recommended application rate is 0.2 lbs/ai per cubic footof wood. This product may be mixed with copper preservative products. Treated wood cannot be usedin direct contact with salt water environments, but can be used in fresh water environments and forabove-ground uses. The inerts do not appear to be solvent carriers.

http://www.dec.state.ny.us/website/dshm/pesticid/pesticid.htm

Mr. Eliot Harrison 2.

Technical Review:

The United States Environmental Protection Agency (USEPA) indicated that Carboquat WP-50 wasused for studies when possible. When it wasn’t, didecyl dimethyl ammonium chloride (DDAC) wasused. USEPA determined DDAC to be acceptable as a surrogate compound after a review of the twocompounds’ chemical and toxicological properties.

Solubility: The MSDS states that product is soluble.

Hydrolysis: DDAC is stable to hydrolysis at pHs 5, 7 and 9.

Anaerobic Aquatic Metabolism: USEPA found this study acceptable. DDAC had half-lives of261 days in water, 4,594 days in sediment and 6,218 days in the entire system. The soil was a sandyloam with 1.6% OM and a pH of 8. The water had a pH of 8.1. No major degradates were found.

Aerobic Aquatic Metabolism: USEPA found this study acceptable. DDAC had half-lives of180 days in water, 22,706 days in sediment and 8,366 days in the entire system. The soil was a sandyloam with 1.6% OM and a pH of 8. The water had a pH of 8.7. No major degradates were found. USEPA stated that DDAC is stable to microbial degradation. This study was called “aerobic aquaticmetabolism,” but was described using a soil/water system.

Aerobic Soil Metabolism: In a study that the USEPA found acceptable, DDAC had a half-life of 1,048 days in a sandy loam soil with a pH of 6.3 and 1.8% OM. No major degradates were found.

Adsorption/Desorption: USEPA found this study partially acceptable, but fulfilled the USEPA datarequirements:

ocSoil Type Desorption K % OM pH

Sand 236,473 0.9 7.4

Sandy loam 230,498 1.8 6.3

Silty clay loam 405,328 4.1 7.9

Silt loam 367,334 4.2 7.4

Leachability From Treated Wood: In an October 1, 2002 memorandum, USEPA reviewed a studytesting the leachability of the product from treated wood. Using Southern Pine Sapwood, and treatedat 0.5X, 1X and 2X of the labeled rate, over 14 days 1.99%, 1.56% and 1.44% of applied,respectively, leached out of the wood samples. The pH of the distilled deionized water was 7.76. Ingeneral, progressively lower amounts leached out each day over the 14-day time period. TheAmerican Wood Preservers’ Association study only requires a 14-day leaching study.

ocComputer Modeling: Because of the very high K s, computer modeling was not seen. Any activeingredient that leaches out of the wood will bind strongly with the soil and not be available forleaching into groundwater.


ocSummary: Even though the aerobic half-life is long, given the extremely high K s, this activeingredient will not be available to leach to groundwater from treated wood that is in contact with soil. Therefore, the groundwater staff have no objection to the registration of this product as labeled.

Ecological Risk Assessment:

Chemical Description:

Carboquat WP50 is a biocide proposed for use as a wood preservative. The activeingredient is didecyl dimethyl ammonium carbonate (DDACarb). This active ingredient belongs toa larger group of related chemicals known as “Quaternary ammonium compounds,” or “quats.” Quats are characterized by the presence of a permanently charged pentavalent nitrogen atom and the

10presence of at least one alkyl chain approximately C or longer, with the general structure:

The R groups may contain N-C or O-C bonds, and they may be branched or linear,substituted or unsubstituted, saturated or unsaturated and aromatic or aliphatic (Boethling & Lynch,undated).

Because quats exhibit generally similar chemical behavior, the USEPA made the decision tocluster them into four groups for the purpose of testing chemicals in order to build a database thatwill support the continued registration of the entire family of quats (USEPA, 1988).

Carboquat WP50 is very similar to Bardac 2250, a similar quat registered in New York inJuly 2003. The active ingredient of Bardac 2250 is didecyldimethyl ammonium chloride (DDAC). The difference between Bardac 2250 and Carboquat WP50 is that Bardac 2250 uses chlorine ion

3 3(Cl ) as the counterion, whereas Carboquat WP50 uses carbonate (CO ) or bicarbonate (HCO ) as- -2 -

the counterion. The carbonate formulation is less corrosive to the pressure vessels used to pressure-treat wood with preservatives than the chloride formulation. Both Carboquat WP50 and Bardac2250 are group I quats as classified by USEPA (1988), so many of the same studies (ofdidecyldimethyl ammonium chloride) used to register Bardac 2250 can be used to registerCarboquat WP50 (with the active ingredient didecyldimethyl ammonium carbonate). WhereasBardac 2250 is registered for a variety of end use applications (e.g., disinfectants, sanitizers,fungicides, wood preservatives, water treatment microbiocides), use as a wood preservative is theonly labeled use for Carboquat WP50.

Toxicity

DDACarb exhibits low dietary toxicity to birds and mammals. The lowest observed effectsconcentration (LOEC) following a 90-day feeding study with rats was 3,000 ppm, and the noobserved effects concentration (NOEC) was 1,000 ppm. The LOEC following similar chronic


feeding studies with mallard ducklings and bobwhite quail was 5,620 ppm, and the no observedeffects concentration (NOEC) was 1,780 ppm. DDACarb is highly toxic to aquatic life. SeeTable 1.

Table 1. Toxicity of DDACarb to aquatic life

50Species Media Test LC , mg/L NOEC, mg/L

rainbow trout (cold water fish) FW 96 hour acute 0.810 0.580

bluegill sunfish (warm water fish)

FW 96 hour acute 0.270 0.098

fathead minnow (warm water fish)

FW 28 day early lifestage (ELS)

LOEC: 0.032 0.018

Daphnia magna (FW invertebrate)

50FW 48 hour acute EC : 0.066 0.033

Daphnia magna (FW invertebrate)

FW 21 day chronic LOEC: 0.046 0.027

Selenastrum capricornutum(green algae)

50FW 96 hour growth EC : 0.026 0.014

Chironomus tentans(insect - midge larvae)

50sediment 14 day EC 1287 530

Saltwater tests were also conducted on marine/estuarine species. However, the labelexpressly prohibits the use of wood treated with Carboquat WP50 in salt water.

It is important to note the toxicity of DDAC to Chironomus tentans when the quat has beensorbed to sediment. Sediment-sorbed DDAC is over 1,500 times less toxic to the least acutelysensitive aquatic species (rainbow trout), and nearly 50,000 times less toxic to the most sensitivespecies, Selenastrum capricornutum (green algae).

Exposure

Environmental fate

The applicant submitted environmental fate studies that were conducted to meet USEPApesticide registration guidelines, including hydrolysis, photolysis, aerobic aquatic metabolism, andanaerobic aquatic metabolism. These studies all indicated that DDAC (surrogate for DDACarb) isstable in the aquatic environment with degradation half-lives ranging from 20 to 60 years. WhileDDAC and DDACarb are stable to hydrolysis and aquatic photolysis, the open scientific literaturereports that quats such as these materials disappear rapidly from water due to sediment sorption andbiodegradation.

USEPA aerobic and anaerobic aquatic metabolism studies are conducted under verystringent conditions that do not emulate natural water bodies. The applicant submitted a study thatshowed acclimation of the microbial community is an essential factor in measuring the microbial


2Ultimate degradation refers to the complete breakdown of an organic compound to CO ,1

2H O, inorganic salts, and new bacterial cells. It is also referred to sometimes as completemineralization.

degradation of group I quats (Lee, 1992). Because they are potent biocides, in closed systems withunacclimated microbial communities, moderately high concentrations of quats can be toxic to themicrobes present. There is usually a lag period before the microbial degradation of quats will begin. However, when discharged into receiving waters where acclimated microbial communities arepresent, microbial degradation of group I quats can be quite rapid. Boethling and Lynch (undated)found that aquatic environments that receive effluent from sewage treatment plants should beacclimated to some quats, and biodegradation rates for these might be quite rapid. They found that

16in one study, A TMAC (alkyltrimethylammonium chloride, another group 1 quat), disappeared

16completely from river water in 7 to 14 days, and in another study, A TMAC degraded with a half-

1/2 2life (T ) of 2.7 days after a 2-day lag. They also reported a study that measured CO from C-14 14

labeled quats with initial concentrations ranging from 1 to 100 ug/L. In that study, ultimate

16 18degradation of A TMAB (alkyl trimethylammonium bromide) and A TMAC in river water1

occurred with no detectable lag, with half-lives of 2 to 3 days.

Quats also have a tendency to sorb strongly to sludge, natural sediments, clay, and othermaterials including minerals, proteins, and cell walls of microorganisms. Sorption is rapid as wellas strong, with equilibrium being established in minutes to hours. (Boethling and Lynch, undated). Such strong sorption can also influence toxicity. Lewis and Wee (1983) evaluated the toxicity ofquats in river water that received wastewater effluent. They found that dialkyl dimethyl ammoniumcompounds were 2 to 3 orders of magnitude less toxic compared to the toxicity in pure water,depending on the wastewater dilution ratio. They reported that the reduction of toxicity was due, inpart, to strong adsorption to natural solids, and the tendency on the part of the quats to formchemical complexes with anionic substances.

Quats can remain biodegradable when sorbed as well, depending on what they are sorbed to. When a quat is adsorbed to koalinite clay, it is still rapidly degraded. However, when a quat isadsorbed to a montmorillonite clay, the quat can be protected from biodegradation because it tendsto be adsorbed to the inner surfaces of the expanding lattice structure of the clay (Boethling andLynch, undated).

Leaching

All of the major wood preservatives tend to leach out of pressure-treated wood to somedegree, and most of the leaching occurs immediately after the treated wood is placed in the water(Sinnott, 2000). In a leaching study, carboquat demonstrated the same response. Small cubes(19 mm) were pressure-treated and placed in water. The amount of DDACarb that leached out overthe next 14 days was evaluated. Depending on the application rate, 1.5% to 2% leached out of thewood over the 14-day period. If the wood continued to leach at that rate, the total amount ofpreservative would completely leach out in 1.9 to 2.6 years, and the life span of the treated wood inwater would probably be a little longer than untreated wood. However, Walker (1994) reported thatwhen used as a wood preservative, quats rapidly bind to both the cellulose and lignin components ofwood, and at equilibrium, lignin holds about four times the amount of quat as the cellulose. The


leaching study did not show a constant rate of leaching. Leaching decreased continuously over the14-day period, and the greatest leaching occurred during the first 6 hours. See Table 2.

Table 2. Leaching of DDACarb during a 14-day leaching study

Day Percent leached

0.25 0.4

1 0.3

2 0.19

3 0.16

6 0.12

8 0.11

10 0.11

12 0.08

14 0.09

If the percent leaching data are extended with a linear regression, it can be demonstrated thatat this rate of decline, leaching reaches 0% at 15.9 days. It is unlikely that leaching ever completelyreaches zero. However, after 15 to 30 days, the volume of DDAC leached each day would be very,very minute.

Risk Characterization

Didecyldimethyl ammonium carbonate/bicarbonate (DDACarb) is a highly toxic to aquaticlife when it is present in the water column. However, when it is adsorbed by the sediments, it isthree to five orders of magnitude less toxic. When released into the water column, DDACarb willbind rapidly to sediments and complex with anionic materials. When bound to sediment, thetoxicity of DDACarb is much lower. It can also be degraded, unless it is bound to a substrate thatprotects it physically, such as to the expanding lattice structure of montmorillonite clay. Even then,it remains biologically unavailable.

When used as a preservative in pressure-treated wood in water, small quantities ofDDACarb will leach out, primarily during the first two weeks. After that initial period, DDACarbwill be bound up with the lignin and cellulose of the wood, and leaching will be minimal.

DDACarb that does leach is likely to be quickly adsorbed by sediments, organic substrate(such as algal cells), suspended solids, etc., and removed from the water column. Once sorbed, ithas the potential to be degraded quickly by microbial degradation. The fraction of DDACarb that isnot sorbed will be degraded in the water column by microbial degradation, probably at half-life ratesof 2 to 3 days. There may be a short acclimation period before biodegradation begins in the watercolumn.

Because the rate of leaching is low and because DDACarb is rapidly removed from thewater column, it is unlikely that when used as a preservative for pressure-treated wood in water,DDACarb will have adverse impacts on aquatic life. Any adverse impacts are likely to occur only


in the first two weeks following installation of the treated wood in the water, and should not persistbeyond the first two weeks.

When used only as a preservative for pressure-treated wood, birds and mammals are notexposed to any significant degree to DDACarb.

Toxicological Risk Assessment:

The Department previously reviewed Carboquat 150T in January 2004. The availableinformation indicated that this product is moderately acutely toxic by the oral route of exposure andis also a severe skin irritant. Based on the toxicological properties of the compound didecyldimethyl ammonium chloride (DDAC) which is chemically very similar to the two activeingredients in Carboquat 150T and WP-50, didecyl dimethyl ammonium carbonate and didecyldimethyl ammonium bicarbonate, these two active ingredients are expected to be moderately toxicfollowing acute oral and inhalation exposures, and to cause severe skin and eye irritation. They alsowould be expected to cause some chronic and developmental toxicity in laboratory animal studies,but to not cause reproductive, oncogenic or genotoxic effects. A search of the toxicologicalliterature did not find any additional information on DDAC, didecyl dimethyl ammonium carbonateor didecyl dimethyl ammonium bicarbonate.

The USEPA conducted a health risk assessment for worker application and post-applicationexposures to the active ingredients in Carboquat WP-50. For this risk assessment, chromatedcopper arsenate (CCA) exposure patterns for workers at pressure treatment facilities were used as asurrogate for workers that treat wood with Carboquat WP-50. In addition, because of the structuralsimilarity of DDAC to the two active ingredients in Carboquat WP-50, some of the toxicityinformation on DDAC was used to conduct this risk assessment. For applicators of CarboquatWP-50 using a final vacuum procedure (as required on the product label) to remove excesstreatment solution from the treated wood surface, the estimated margins of exposure (MOEs) fordermal and inhalation exposures were 310 and 110,000, respectively. For these estimates, it wasassumed that these workers used some of the personal protective equipment (PPE) required on theCarboquat WP-50 product label (long-sleeved shirt, long pants and chemical-resistant gloves). TheCarboquat WP-50 label also requires the use of chemical-resistant footwear and socks, protectiveeyewear and, in some cases, a respirator. The no-observed-effect levels (NOELs) used forestimating the dermal and inhalation MOEs were 12 milligrams per kilogram body weight per day(mg/kg/day) for systemic effects from a 90-day rat dermal toxicity study with DDAC and10 mg/kg/day from a rat developmental toxicity study with DDAC, respectively. For post-application worker (those involved in handling freshly-treated wood) dermal and inhalationexposures, the respective estimated MOEs were 170 and 67,000. Generally, the USEPA considersMOEs of 100-fold or greater to provide adequate worker protection.

The USEPA also conducted a health risk assessment for residential post-applicationexposure to Carboquat WP-50 by children. This assessment assumed that the residues on children’shands were the same as the average DDAC residues measured on workers involved in handlingtreated lumber. For children’s dermal contact and hand-to-mouth contact, the respective MOEswere 80 and 360. The MOE of 80 for children’s dermal contact is less than the 100-fold or greatervalue generally considered by USEPA to provide adequate protection. The NOEL used forestimating this MOE was 12 mg/kg/day for systemic effects from the 90-day rat dermal toxicity


study. For children’s hand-to mouth contact, the NOEL used for estimating the MOE was10 mg/kg/day from a rat developmental toxicity study with DDAC.

There are aspects of the USEPA occupational and residential risk assessments that areeither problematic or create uncertainty. Firstly, the analyses compared dermal exposures ofworkers and children to a NOEL of 12 mg/kg/day for systemic effects from a 90-day rat dermaltoxicity study with DDAC. Such an approach is reasonable for evaluating systemic effects. However, there is some uncertainty about which toxicity data are most appropriate to compare todermal exposure estimates. Regardless of which study data are most appropriate to evaluatesystemic effects, dermal irritation is also a concern with didecyl dimethyl ammonium carbonate anddidecyl dimethyl ammonium bicarbonate, and this endpoint should be evaluated. When evaluatingthe potential for dermal irritancy, the basis of comparison between exposure and local effect isperhaps best done as a function of active ingredient per area of skin surface. The exposureestimates provided do not allow such a comparison for all exposed skin surfaces of workers, but doallow comparison for hands of post-application workers and hands of children who contact treatedsurfaces. Using the average skin residues on workers (1.4 micrograms per square centimeter skin(mg/cm )) and the NOEL for irritation in the 21-day dermal study in rats (7.8 mg/cm ), a MOE of2 2

about 6 can be calculated for skin irritancy.

An additional factor to consider in the risk assessments is that the USEPA based dermalexposure estimates on treatment solutions of Carboquat WP-50 with a final concentration of 1.0%didecyl dimethyl ammonium carbonate and didecyl dimethyl ammonium bicarbonate. However, theproduct label also permits Carboquat WP-50 to be used at solution strengths up to 3.0% didecyldimethyl ammonium carbonate and didecyl dimethyl ammonium bicarbonate. Using CarboquatWP-50 in this manner would increase by three-fold the potential dermal exposure to these twoactive ingredients. In addition, there are other uncertainties and data gaps associated with the riskassessment analyses that affect the estimation of MOEs. These include, as pointed out by theUSEPA: 1) concern for extrapolating the anticipated residues found on workers’ hands to theexposed surface area of children’s hands, 2) the assumption that exposure patterns for workers atpressure treatment facilities using CCA would be similar for workers that treat wood withCarboquat WP-50, and 3) the lack of residue dislodgeability data for Carboquat WP-50 treatedwood.

There are no chemical specific federal or State drinking water/groundwater standards fordidecyl dimethyl ammonium carbonate and didecyl dimethyl ammonium bicarbonate. Based ontheir chemical structures, these compounds fall under the 50 microgram per liter (mg/L) generalNew York State drinking water standard for “unspecified organic contaminants” (10 NYCRRPart 5, Public Water Systems). The New York State drinking water standard for the sum of“unspecified organic contaminants” and “principal organic contaminants” is 100 mg/L.

Based on the toxicological properties of the chemically similar compound DDAC, the twoactive ingredients in Carboquat WP-50, didecyl dimethyl ammonium carbonate and didecyldimethyl ammonium bicarbonate, would be expected to have moderate acute toxicity via oral andinhalation exposures and to cause severe skin and eye irritation. They also would be expected tocause some chronic and developmental toxicity in laboratory animal studies, but not to causereproductive, oncogenic or genotoxic effects. As for the likelihood of causing effects in humans,there are a number of elements in the risk assessments provided for workers and post-applicationresidential exposure of children that raise questions and create uncertainty. Also, the estimated


MOEs for these individuals in some cases are below levels generally considered to provide adequateprotection. Due to the uncertainties and data gaps associated with the MOE determinations, theUSEPA required the registrant to submit: 1) a 21-day dermal toxicity study on the end-useformulation, and 2) “Surface Residue Wipe” data using methodology consistent with that used forCCA-treated wood. The Department has decided that these data, and an evaluation based on thesedata, are important to characterizing the risks associated with use of the Carboquat WP-50. Consequently, the Department has reservations against the registration of Carboquat WP-50 inNew York State until a risk assessment based on the results of these two studies demonstrate thatexposure to the active ingredients of this product pose no significant risk of systemic effects or localskin irritancy to children or workers who contact treated wood, or to workers involved in thehandling of this product. Also, if the product is subsequently registered in New York State, thelabel should be revised to require the use of chemical splash goggles or a face shield to ensure eyeprotection against the corrosive properties of the Carboquat product, rather than genericallyrequiring “protective eyewear” as is currently on the label. This revision is also consistent with therecommendation on the Material Safety Data Sheet for the Carboquat WP-50 product.

Since the initial DOH evaluation (January 24, 2005), the acting agent for the registrantsubmitted information (see correspondence from E. Harrison to C. Crowley, April 17, 2006 andApril 24, 2006), on a 21-day dermal irritation study. In this study, female rats that were exposed tothe active ingredients didecyl dimethyl ammonium carbonate/bicarbonate at a skin application rateof 10 micrograms per square centimeter (µg/cm²) exhibited only slight skin irritation. Based on thisobservation, the study authors reported that the NOEL for Carboquat WP-50 to induce skinirritation would be 10 µg/cm² (the lowest application rate tested). However, some effects werefound at this application rate and it could be argued that this level really represents alowest-observed-effect level (LOEL). No systemic effects were evaluated in this study other thanclinical observations and body weight measurements.

The registrant/agent also submitted two studies which we reviewed (see correspondencefrom J. Leach to S. Jackling, September 14, 2006) that evaluated the amount of Carboquat residuesthat would be dislodged from pressure-treated wood (either Southern yellow pine or white spruce)under conditions that simulate residential post-application exposure to this wood. However, theydid not provide a risk assessment for workers or residents who may contact wood treated withCarboquat. Based on a simple comparison of dermal residue transfer and dermal irritation data,MOEs from about 12 to 71 and 4 to 43 for Southern yellow pine and white spruce, respectively,were calculated. This simple comparison does not take into consideration the likelihood forcontinual contact by workers with treated wood as occurs during the construction of structures suchas decks, sheds, etc., nor does it consider the potential for systemic effects. Given that there arequestions about which MOE values provide adequate protection, we recommended that CarboquatWP-50 not be registered in New York State until such time that the USEPA has completed theiranticipated risk assessment for post-application exposure to this product and we determine, basedon this analysis, that the estimated risks of both dermal and/or systemic effects are acceptable.

The registrant has now submitted further additional information (see correspondence fromE. Harrison to C. Crowley, February 5, 2007 and March 2, 2007). The information included: 1) theUSEPA's Reregistration Eligibility Decision (RED) for Didecyl Dimethyl Ammonium Chloride(DDAC). (The only difference between DDAC and Carboquat WP-50's active ingredients is the anion: DDAC contains chloride while the anion in Carboquat WP-50 is carbonate/bicarbonate);


2) the USEPA's draft DDAC Occupational and Residential Exposure Assessment; and 3) aregistrant-sponsored risk assessment for children playing on wood decks and playground equipmenttreated with Carboquat.

The USEPA RED indicates that a target MOE of 10 would provide adequate protection fromdermal irritation to DDAC and, therefore, presumably Carboquat WP-50's active ingredients. TheUSEPA stated: "The target MOE was chosen because the established endpoint is for dermalirritation, not a systemic effect. In addition, dermal irritation is considered a reversible andshort-term effect, thus, supporting a 10x uncertainty factor (3x for interspecies extrapolation and 3xfor intraspecies variation)." Therefore, the registrant by submitting this RED to us has provided therequested documentation of which MOEs USEPA considers to provide adequate protection forproducts such as Carboquat WP-50. However, neither did this RED nor the submitted USEPA'sdraft Occupational and Residential Exposure Assessment include a risk assessment based on thepreviously noted 21-day dermal irritation study and the surface residue wipe studies.

Although the USEPA did not use the two recent studies to conduct a risk assessment forexposure to wood treated with the Carboquat product, the registrant submitted a risk assessmentbased on these data for children playing on wood decks and playground equipment treated withCarboquat. Utilizing data from the surface residue studies, the registrant estimated that theCarboquat residues that would be transferred to a person's hand from treated Southern yellow pineand white spruce boards would be 0.30 and 1.07 µg/cm², respectively. These values were based oncalculated average residues over a 30-day period after wood treatment. When these residue levelsare compared with the level that caused slight dermal irritation in the 21-day rat study (10 µg/cm²),the respective MOEs are 33 and 9. For long-term dermal exposure (i.e., greater than 30 days), therespective MOEs are 71 and 43. All these MOEs, therefore, appear to be very close to or above theacceptable level of 10 for adequate protection from dermal irritation. However, as previously noted,we have some reservations about accepting 10 µg/cm² as the NOEL for dermal irritation, sincesome effects were found at this application rate and, therefore, a MOE of greater than 10-fold maybe more appropriate. The registrant has stated that the 10 µg/cm² level is clearly a NOEL because:1) only minimal erythema was observed; 2) no edema was present; 3) the erythema was not seen inthe same animals on all days; 4) not all animals had erythema; 5) the maximum Primary DermalIrritation score was less than 1; and 6) no lesions were observed during histopathological evaluationof treated skin.

The registrant did not conduct a risk assessment for workers who may handle treated woodduring the construction of decks and other structures. They state that such a risk assessment is notnecessary because they believe that the only toxicity endpoint of concern is dermal irritation andthat the potential risks to construction workers who handle treated wood is addressed by USEPA. To support this view, the registrant quoted the USEPA draft DDAC Occupational and ResidentialExposure Assessment which states: "Currently, there are no study data that can be used to estimateeither exposure to adults during construction of wood decks or to children exposed to treated wood. Incidental ingestion exposure for adults is expected to be negligible and dermal contact for adults isexpected to be lower than children for [sic] crawling and playing on decks. Because childrenexhibit a more intense play contact on surfaces and have a higher surface area to body weight ratio,they would generally be considered to represent the maximum exposed individual." The registrantfurther points out that USEPA states "[P]otential risks resulting from construction worker dermalcontact with DDAC-treated wood are assessed in the same manner as potential risks resulting fromchildren's dermal contact with DDAC-treated playsets and decks." Thus, they conducted a risk


assessment for children, but not for workers. It should be noted, however, that the above USEPAdraft assessment was apparently conducted prior to their review of the dermal irritation study andthe wood residue dislodgeability studies.

In summary, the registrant has submitted additional information that helps to address someof our concerns. The registrant amended the Carboquat WP-50 label to incorporate the requirementto use chemical splash goggles or a face shield as we requested in a previous review. They alsosubmitted documentation from USEPA wherein the agency establishes a target MOE of 10 asadequately protective from dermal irritation due to contact with Carboquat-treated wood. If aNOEL for dermal irritation of 10 µg/cm² is used as a basis for comparison with dislodgeable residuelevels from Carboquat-treated wood, then estimated MOEs of about 10 or greater should provideadequate protection. However, DOH believes that 10 µg/cm² is not a true NOEL as some dermalirritation (in the form of very slight erythema) was reported at this level, and that this response wasan early step in the increasingly significant irritation (in the form of more severe erythema andedema) that occurred in the higher application rate groups (20 µg/cm² and 30 µg/cm²). Consideringthis, one could argue that the target MOE that would provide adequate protection should be greaterthan 10-fold. If the target MOE is set at 100, then neither the MOE for dislodgeable residuesaveraged over a 30-day period from Carboquat-treated Southern yellow pine nor fromCarboquat-treated white spruce would provide adequate protection against dermal irritation. Furthermore, even if the acceptable NOEL is 10 µg/cm², the estimated MOEs from post-applicationdermal contact to Carboquat-treated white spruce would not provide adequate protection for up to atleast 13 days subsequent to treatment (i.e., the estimated MOE at day 13 is 5). That is because theresidues up to at least day 13 would be greater than those used in the risk assessment, which werebased on a 30-day average value. A more conservative comparison would be made using residuespresent at time points of 13 days post-treatment or less (we acknowledge, however, that more timemay elapse between the treatment of wood products and their use by workers and contact of decksand playground equipment by children). Also, DOH does not fully agree with the registrant's beliefthat inhalation exposures to DDAC from treated wood would be minimal given that sawing andother construction activities can release considerable wood dust that would contain the activeingredient and could contact the respiratory tract.

Given the above, the Department still has some reservations about the registration ofCarboquat WP-50 in New York State as an end-use product. DOH believes that dermal contact,and perhaps inhalation, may cause irritation effects in those who handle treated wood duringconstruction activities or who otherwise contact treated surfaces. A recent case report (Rowden,A. K., et al. 2005. Clinical Toxicology. 43(6): 751), demonstrates the potential for this formulatedproduct to cause significant dermal irritation and chemical burns. Although the registrant providedsome information to assess risks to workers and children, the actual extent to which wood treatedwith Carboquat can cause irritation or other effects in humans is not known. The DOH would notobject to registration of Carboquat WP-50 if the registrant is required to either: 1) develop atracking system (possibly through the use of FIFRA 6(a)(2) reports) to provide information on anyadverse effects to children and adults from exposure to Carboquat-treated wood or to workershandling the Carboquat product; or 2) provides additional information/evaluation that adequatelyaddresses the issue of the NOEL/LOEL for dermal irritation, the potential to cause irritant or othereffects following inhalation exposure, and provides current and historical information on anyadverse reactions among workers or others who contact treated surfaces.


In response to the above request by the Department, Lonza decided to proceed with Option 1(see correspondence from E. Harrison to C. Crowley, September 5, 2007) which states:

1. Wood treaters using Carboquat WP-50 will add either a web-site address or thetelephone number of the treater to the end tag that is stapled to every piece of treatedwood; and

2. In accordance with FIFRA Section 6(a)(2), either Lonza or distributors of CarboquatWP-50 will submit all pertinent incident reports to the Department.

Based on the above-mentioned information, the Department hereby accepts CarboquatWP-50 (EPA Reg. No. 6836-304) for general use registration with the following conditions:

1. The registrant (preferably in coordination with other registrants who may sell didecyldimethyl ammonium carbonate/bicarbonate (or chemically similar) wood preservativeproducts in New York State) must develop a system for providing the Department withinformation on any adverse reactions among humans, as described above. Informationmust be provided annually.

2. All registrants of USEPA registered didecyl dimethyl ammoniumcarbonate/bicarbonate (or chemically similar) wood preservative products must submitcopies of any adverse effects notifications submitted to the USEPA in accordance withFIFRA 6(a)(2) to the Department regardless of New York State registration status.

3. The Department and the New York State Department of Health will closely monitorand review any didecyl dimethyl ammonium carbonate/bicarbonate (or chemicallysimilar) wood preservative products adverse effect reports. The Department will reactquickly and pursue mitigative measures deemed necessary in order to protect the healthof the residents of New York State.

4. The continued registration of the above-mentioned product(s) and subsequentlyregistered didecyl dimethyl ammonium carbonate/bicarbonate (or chemically similar)wood preservative products in New York State will be dependent upon thedevelopment of an acceptable tracking system and the submission of all adversereaction reports to the Department.

Enclosed are your Certificate of Pesticide Registration and New York State stamped“ACCEPTED” label.

Lewis & Harrison on behalf of their client, Lonza, Inc., is reminded that if New York Stateregistration is requested for the above product or any other didecyl dimethyl ammoniumcarbonate/bicarbonate wood preservative products (or chemically similar), which contain anexpansion of use patterns or potentially increase exposure, the product will be considered a MajorChange in Labeling and the Department will require an extensive review.


If you have any questions, please contact Samuel Jackling, Chief of our Pesticide ProductRegistration Section, at (518) 402-8768.

Sincerely,

Maureen P SerafiniMaureen P. SerafiniDirector

Enclosures Bureau of Pesticides Management

ecc: w/enc. - A. Grey/E. Horn, NYSDOHR. Mungari, NYS Dept of Ag & MarketsW. Smith, Cornell University, PMEP

LITERATURE CITED:

Boethling, R. S., and D. G. Lynch, undated. Quaternary Ammonium Surfactants. U. S.Environmental Protection Agency, Office of Toxic Substances, TS-798, 401 M. Street, SW.,Washington, D.C. 20460, undated manuscript.

Lee, C. M., 1992. Assessment of the Biodegradability of ADBAC and DDAC. Roy F. Weston, Inc., One Weston Way, West Chester, PA. 19380.

Lewis, M. A., and V. T. Wee, 1983. Aquatic safety assessment for cationic surfactants. Environmental Toxicology and Chemistry, 2:105 - 118, 1983.

Sinnott, 2000. Assessment of the Risks to Aquatic Life from the Use of Pressure Treated Wood inWater. New York State Department of Environmental Conservation, Division of Fish, Wildlife andMarine Resources, March 2000.

U. S. EPA, 1988. Clustering of Quaternary Ammonium Compounds. PR Notice 88-2, U. S. Environmental Protection Agency, Office of Pesticides and Toxic Substances, Washington, D.C.,February 26, 1988.

Walker, L. E., 1994. Alkylammonium Compounds as Wood Preservatives. FPS Wood ProductsProtection Conference, September 28, 1994.

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