2

EFED Response: The Agency intends to evaluate the potential impacts of dichlobenil uses 

that are indicated to potentially impact the biological processes used by municipal 

wastewater treatment plants. The results of activated sludge respiration inhibition studies 

(OCSPP guideline 850.3300; formerly OPPTS guideline 850.6800) are used as a first step to 

evaluate the potential impact to wastewater treatment facilities. Therefore, EFED asks that 

the Pesticide Re-evaluation Division (PRD) require submission of activated sludge 

respiration inhibition studies on dichlobenil and BAM. These studies were not requested in 

the original problem formulation for registration review (DP barcode 396247), but are 

requested in an updated problem formulation (DP barcode 407305) to address concerns 

raised in comments such as SFBWB’s that were submitted for the registration review of 

dichlobenil.

The Draft Assessment Report (DAR) for dichlobenil prepared in the European Union (The 

Netherlands, 2008) identifies activated sludge respiration inhibition and ready 

biodegradability studies on dichlobenil (Mead, 2002) and a ready biodegradability study (but 

not an activated sludge respiration inhibition study) on BAM (Van der Laan-Straathof and 

Philips-Van Loo, 1996) that may provide useful information. EFED requests submission of 

these studies for review. If Mead (2002) is acceptable upon review, then an activated sludge 

respiration inhibition study of BAM will remain requested (because this information 

regarding BAM has not been located). If Mead (2002) is unacceptable upon review, then 

activated sludge respiration inhibition studies of dichlobenil and BAM will remain requested.

SFBWB Comment: “We support the Bay Area Clean Water Agencies’ request that the 

registrant be required to develop analytical methods that would allow us to examine whether 

a wastewater treatment process interference incident may be linked to dichlobenil.”

EFED Response: The Agency requires pesticide manufacturers to submit analytical methods 

in water and soil or sediment for residues of concern that have limits of quantitation (LOQ) 

below toxicological levels of concern. OCSPP guideline 850.6100 states, “For a given 

sample matrix, the registrant should select the most difficult analytical sample condition from 

the study (e.g., high organic content versus low organic content in a soil matrix) to analyze 

from the study to demonstrate how well the method performs.” Therefore, if media found in 

wastewater treatment plants, such as wastewater effluent and biosolids, are found to be more 

difficult to analyze than typical environmental media, such as agricultural water and soil, 

respectively, and toxicological levels of concern in these media may be exceeded, then 

analytical methods specific to the treatment plant media will be required of the 

manufacturers. If treatment plant media are found to be easier to analyze than typical 

environmental media, then analytical methods for typical environmental media should be 

adequate for analyses of treatment plant media. If dichlobenil residues of concern are not 

expected to exceed toxicological levels of concern in treatment plant media, then analytical 

methods for treatment plant media are unnecessary.
3

2. California Stormwater Quality Association (CASQA)

CASQA Comment: “CASQA’s primary concern regarding registration of dichlobenil is the 

potential for it to be used in ‘storm sewers, drain lines, and drains’ ... [which] usually flow 

directly to creeks, rivers, estuaries, or the ocean without any treatment” “Use of dichlobenil 

in storm drains could directly result in fish kills, along with impacts to aquatic plants.” 

“CASQA recommends adding ‘Do not use this product in a separate storm drain system.’ to 

the label.” “In the unlikely event that the registrant wishes to retain label language that 

allows for application in storm drains, U.S. EPA should complete a full environmental 

assessment” for this use.

EFED Response: Many of the comments received from CASQA and other commenters for 

the registration review of dichlobenil pertain to language on the pesticide labels. EFED 

cannot respond to these comments since they are the purview of the risk managers who 

review the labels. If dichlobenil labels retain the use in storm drains, EFED will assess 

exposure to aquatic organisms from this use, as indicated in the analysis plan of the problem 

formulation for registration review, and as part of a full ecological risk assessment for this 

use.

3. Bay Area Clean Water Agencies (BACWA)

BACWA Comment: “We request that EPA require a sludge respiration inhibition test ... and 

consider all available open literature to assess the potential for wastewater treatment process 

interference. We have attached two studies that may assist in this effort.”

EFED Response: The Agency appreciates the submission of data relevant to the potential 

for wastewater treatment process interference due to use of dichlobenil. The Agency will 

consider the available literature relevant to wastewater treatment process interference. Upon 

preliminary review, the available data indicate that use of dichlobenil will not impede 

wastewater treatment processes.

The results of Yeung and Criddle (2007) indicate, upon preliminary review, that dichlobenil 

may temporarily alter the dominant lineages of ammonia oxidizing bacteria. However, this 

did not inhibit ammonia oxidation at dichlobenil concentrations up to 2.75 mg a.i./L. At 5.0 

mg a.i./L, dichlobenil may have inhibited ammonia oxidation (statistical significance was not 

noted) during the early exposure period, with full recovery of ammonia oxidation after 48 

hours. Nitrite oxidation was not inhibited (Yeung and Criddle, 2007).

An activated sludge respiration inhibition study (Mead, 2002) submitted to the European 

Union and reported in the Draft Assessment Report (DAR) for dichlobenil indicated, upon 

preliminary review, that the compound did not inhibit bacterial respiration at concentrations 

up to its water solubility limit (i.e., the 3-hour EC50 for activated sludge due to respiratory 

inhibition was >21 mg a.i./L).

BACWA Comment: “In designing its process interference risk assessment, EPA should use a 

quantitative approach. Quantification of risks will provide the basis for future risk
4

management. Both pesticide control operators and wastewater facility operators would 

benefit from specific guidance on how to calculate how much root control product may be 

safely applied within a wastewater collection system. This would ideally be a ‘maximum 

allowable headworks loading’ formula that would provide a simple formula to calculate the 

maximum hourly and daily quantity of a root control product that can be allowed in a 

treatment plant’s influent stream.”

EFED Response: The Agency will consider this recommendation when conducting the 

ecological risk assessment. A quantitative approach such as this may be desirable for 

pesticides found to potentially impact treatment plants. A preliminary review of the available 

data, however, indicates that dichlobenil uses will not impede wastewater treatment 

processes (Mead, 2002; Yeung and Criddle, 2007).

BACWA Comment: BACWA supports EPA’s plan to use the E-FAST down-the-drain model 

and requests that the assessment conceptual models “explicitly indicate that dichlobenil use 

in sanitary sewers is an exposure pathway.”

EFED Response: The assessment conceptual models are largely graphical simplifications of 

the assessment analysis plans. Therefore, the analysis plan carries more weight than the 

conceptual models. It is not important to explicitly indicate in the conceptual models that 

dichlobenil use in sanitary sewers is an exposure pathway if the analysis plan indicates that 

this is so.

BACWA Comment: “The environment within a wastewater collection system differs greatly 

from the outdoor environment. There is little to no light, it is often cooler in summer and 

warmer in winter than temperatures above ground, and the air may contain more ammonia, 

nitrogen and sulfur-based compounds, carbon dioxide and/or methane resulting from 

bacteriological processes that already have begun to break down sewage within the lines. All 

of these conditions and others may affect the fate of dichlobenil, perhaps modifying its halflife, creating unique reaction products, or causing formation of different degradates. We 

request that EPA consider these possibilities during its review.”

EFED Response: The Agency considers the guideline environmental fate studies specified 

by the Code of Federal Regulations to be adequately protective for degradation processes in 

wastewater collection systems. The increased microbial presence in these systems is 

expected to result in similar to shorter degradation half-lives than in soils or surface waters, 

such that typical environmental fate studies would be protective. The absence of light can be 

assessed with available data. Lastly, the increased presence of airborne biodegradation 

products other than carbon dioxide may result in unique dichlobenil degradates; however, the

potential production of unique dichlobenil degradates is not expected to be substantial. 

Therefore, it is not expected that the risks from these potential degradates will need to be 

quantified.

BACWA Comment: “BACWA supports the EPA requirement for acute toxicity data for 

freshwater fish and aquatic plants for the degradate BZZ. In addition, we request that EPA 

require of the registrant acute invertebrate, chronic fish and invertebrate, and 
5

estuarine/marine fish and invertebrate studies for BZZ. These data are necessary for the 

Down-the-Drain assessment to evaluate the potential environmental risks from BZZ, which 

may occur in wastewater effluent.”

EFED Response: Environmental fate and ecotoxicity studies on BZZ are requested because 

its behavior and effects in the environment are not well understood. However, the number of 

requested studies is limited because the compound is not known to be more toxic than 

dichlobenil. The requested studies are on the most acutely sensitive freshwater aquatic 

animal and the most sensitive aquatic plant to dichlobenil, which should provide an adequate 

screen while limiting the resource burden for the data request. The risk assessment will 

assume that the relative toxicity of BZZ compared with dichlobenil observed in the most 

sensitive species is similar across other aquatic organisms. Uncertainty introduced to the risk 

assessment from this assumption will depend on the results of the forthcoming data and will 

be addressed in the risk assessment.

BACWA Comment: “During the registration process, pesticide registrants are required to 

submit analytical methods for commodity residue measurements; however, they are not 

currently required to provide sufficiently sensitive analytical methods for the analysis of 

pesticides at environmentally relevant concentrations for environmentally relevant matrices, 

such as wastewater, surface water, sediments, wastewater effluent and biosolids ... In the 

case of dichlobenil, our primary need is for analytical methods that would allow us to 

examine whether a wastewater treatment process interference incident may be linked to 

dichlobenil. We appreciate that EPA is requiring independent laboratory verification of 

environmental chemistry methods (ECMs) for dichlobenil and BAM in mud, fish, and water 

that will provide method detection limits that are environmentally relevant. BACWA 

requests that EPA also require of the registrant ECMs for BZZ with appropriate method 

detection limits, and as noted above, that the methods are practicable in commercial and 

government laboratories.”

EFED Response: The Agency is requesting independent laboratory validation for an 

analytical method in water for dichlobenil and BAM. The analytical method should be 

practicable in commercial and government laboratories. However, the Agency does not 

require registrants currently to incorporate pesticide analytes into existing multi-residue 

methods for ease of analysis of environmental media. This work is typically performed by 

laboratories that analyze monitoring samples, as indicated in the comment. 

Concentrations of BZZ alone are unlikely to exceed risk levels of concern for aquatic 

organisms (although acute toxicity data are needed to confirm whether risk levels of concern 

are exceeded). Therefore, an analytical method for BZZ in water is not requested. 

Wastewater treatment facility matrices are not expected to be environmentally relevant for 

BZZ because the compound is a photodegradate and should not be formed in wastewater 

systems, which tend to be enclosed or otherwise attenuate illumination.
6

4. Tri-TAC

Tri-TAC Comment: “The Technical Advisory Committee for the California Association of 

Sanitation Agencies (CASA), the California Water Environment Association (CWEA), and 

the League of California Cities (LOCC) would like to add our support to the [BACWA 

comments]...Since dichlobenil is a commonly-used root control chemical in sewers, Tri-TAC 

is particularly interested in this registration.”

EFED Response: The Agency appreciates and is carefully considering all submitted

comments. 

5. National Association of Clean Water Agencies (NACWA)

NACWA Comment: “NACWA also supports the more detailed comments and information 

submitted by [BACWA]...It is essential that the pesticide registration process adequately 

consider impacts to wastewater treatment processes, so that such impacts are prevented 

before they result in impairments to water quality and violations of CWA permit 

requirements...Costs to address these problems can mount quickly.”

EFED Response: As previously noted, the Agency intends to assess the risk to wastewater 

treatment plant microorganisms from pesticides used for sewer root control.

NACWA Comment: “NACWA...requests that EPA require a sludge respiration inhibition 

test...[and] consider all available studies and literature to assess the potential for wastewater 

treatment process interference.”

EFED Response: As indicated in the response to BACWA’s similar comment, preliminary 

review of the available data indicates that use of dichlobenil will not impede wastewater 

treatment processes. An activated sludge respiration inhibition study (Mead, 2002) 

submitted to the European Union and reported in the Draft Assessment Report (DAR) for 

dichlobenil indicated that the compound did not inhibit bacterial respiration at concentrations 

up to its water solubility limit (21 mg a.i./L, MRID 40600605). A study by Yeung and 

Criddle (2007) indicates that dichlobenil may temporarily alter the dominant lineages of 

ammonia oxidizing bacteria. However, this did not inhibit ammonia oxidation at 

concentrations up to 2.75 mg a.i./L. At 5.0 mg a.i./L, dichlobenil may have inhibited 

ammonia oxidation (statistical significance was not provided) during the early exposure 

period, with full recovery of ammonia oxidation after 48 hours. Nitrite oxidation was not 

inhibited (Yeung and Criddle, 2007).

NACWA Comment: “In designing its process interference risk assessment, EPA should use a 

quantitative approach.”

EFED Response: The Agency will consider this recommendation when conducting the 

ecological risk assessment. A quantitative approach such as this may be desirable for 

pesticides found to potentially impact treatment plants. A preliminary review of the available 
7

data, however, indicates that dichlobenil uses will not impede wastewater treatment 

processes (Mead, 2002; Yeung and Criddle, 2007).

6. Physicians Committee for Responsible Medicine (PCRM)

PCRM Comment: “We recommend that OECD Test Guideline 223, Avian Acute Oral Toxicity 

Test, be used as the protocol instead of EPA Guideline 850.2100 in the interest of reducing 

the numbers of animals used by up to 61%.”

EFED Response: The Agency recently completed its review of the OECD validation report 

to determine if the TG223 effects endpoints and dose/response information adequately 

address the purposes of the avian acute oral data requirement as described in 40 CFR Part 

158 and 40 CFR Part 161. The Agency determined that studies conducted using TG223 may 

be classified as 'acceptable' if it is scientifically valid, is conducted using the ‘LD50- slope 

test' or 'limit dose test' guidelines (the ‘LD50 - only test' is not adequate for fulfilling data 

requirements), and meets all of the following criteria:

• The study is conducted using bobwhite quail (other test species may be acceptable if they 

have low background mortality in the laboratory and do not regurgitate during the study). 

The background mortality data for the species in question should be available from the 

submitting laboratory at the time of the Agency review.

• The chemical being tested does not cause delayed effects.

• For a 'limit dose test', it is conducted at 2,000 mg a.i./kg-bw or the environmentally 

relevant concentration (whichever is greater).

• For the 'LD50 - slope test', the raw data and results are submitted electronically using the 

SEquential DEsign Calculator (SEDEC) (the Excel calculator that determines the 

placement of doses during testing and is used to estimate the LD50, slope and confidence 

limits for TG223 studies).

• The study meets the same validity requirements as 850.2100 (e.g., a study should be 

invalidated if >10% of the controls die).

• Control birds are not added during the course of the study.

Studies that deviate from the above criteria may be classified as 'acceptable' or 'supplemental' 

if they are considered adequate for use in risk assessment or 'invalid' if they are not 

scientifically sound; however, any TG223 study that deviates from the above criteria will 

need additional evaluation by the Agency to confirm the study’s classification. The 

Agency’s Guidance for Classifying Studies Conducted Using the OECD Test Guideline 223 

is available online at: 

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/terrestrial_biolog

y_tech_team/review_avian_acute_oral_oecd_tg223.htm.

PCRM Comment: “We encourage the use of (Q)SAR data in place of the fish experimental data 

for BZZ. The Agency can use the OECD (Q)SAR Toolbox to compare the toxicity of both

degradates BZZ and BAM to Dichlobenil. Because the Agency is only looking to determine 

the relative toxicity of the degradates compared to Dichlobenil, QSAR analysis, such as that 
8

conducted using models within the Toolbox, may prove useful in fulfilling the Agency’s 

information needs.”

EFED Response: EPA considers SAR/QSAR (Structure Activity Relationship/Quantitative 

SAR) predicted estimates to address data requirements on a case-by-case basis. Uncertainty 

in those predicted estimates is considerably higher than in measured experimental data. 

Although QSAR estimates may be considered in a weight of evidence analysis, experimental 

data are generally required when risks cannot be confidently dismissed based solely on the 

QSAR estimates. ECOSAR results for BZZ indicated that BZZ may be equally or more 

toxic to aquatic organisms than dichlobenil. Therefore, risk could not be dismissed based on 

these QSAR estimates and experimental data is required. In the absence of data, an 

assumption of equal toxicity of BZZ to the parent may be made. If BZZ is less toxic than 

dichlobenil to aquatic organisms, this assumption would be overly conservative. If BZZ is 

more toxic than dichlobenil to aquatic organisms, this assumption would result in an 

assessment that may not be protective of aquatic organisms.

PCRM Comment: “If the Agency continues to request the Acute Fish Toxicity Study for the 

degradate BZZ then following an acute threshold or “limit test” approach can reduce the 

number of animals used, and also, here, provide an indication of relative toxicity. This 

approach was first pioneered on the observation that fish are rarely more sensitive than algae 

and daphnia. The fish median lethal concentration (LC50) test is replaced with an acute

threshold test in which fish testing would be performed at one concentration only (the lowest 

EC50 concentration obtained with previous algae and daphnia testing). A version of this 

approach has been adopted by the OECD as a guidance document.”

EFED Response: Limit tests may be acceptable if no mortality occurs at test concentrations 

that are 20x higher than peak estimated environmental concentrations (EECs). A factor of 20 

is used because the endangered species LOC is 0.05, which represents a value that is 20-fold 

lower than the LC50. 

7. Chemtura AgroSolutions (Chemtura)

Chemtura Comment: “EPA’s assumption that dichlobenil ‘...is stable to all routes of 

degradation except aqueous photolysis...’ is incorrect. As a result the basis of the OPP 

memorandum [DP barcode 399718] is uncertain.”

Chemtura’s arguments in support of this comment included references to dissipation halflives from MRIDs 41340601 and 43522701 that include volatilization and a reference to an 

unpublished aerobic soil metabolism study by Lynn et al. (2003) in which dichlobenil 

degraded with half-lives of 71-101 days and dissipated with half-lives of 65-80 days.

EFED Response: The HED memorandum, DP barcode 399718 (USEPA, 2012), stated that 

“dichlobenil’s main route of dissipation in warm environments is volatilization.” 

Volatilization is a dissipation process, not a degradation process. As seen in Table 2 of 

EFED’s problem formulation for the registration review of dichlobenil, based on the 

available data, dichlobenil degradation (not dissipation) half-lives for processes other than 
9

aqueous photolysis range from 324 days to greater values. These data indicate that “under 

conditions where dichlobenil does not volatilize or photolyze, the compound persists.” 

EFED agrees that DP barcode 399718 overstated the case in the statement that dichlobenil “is 

stable to all routes of degradation except aqueous photolysis.” However, with degradation 

half-lives of 324 days or greater, the compound can be considered very persistent to all routes 

of degradation except aqueous photolysis. Photolytic products are important for compounds 

that mainly degrade via photolysis, even for compounds with only terrestrial uses that only 

photolyze in water, since residues on soil may runoff to water bodies. Therefore, the Agency 

believes the basis of DP barcode 399718 is well supported, despite the poor use of the term 

“stable.”

Chemtura’s arguments based on dissipation half-lives from MRIDs 41340601 and 43522701 

that include volatilization are irrelevant to their conclusion regarding dichlobenil’s 

degradation routes because degradation routes do not include dissipation (and degradation 

has increasing importance in conditions of decreasing temperature).

The Agency invites the submission of Lynn et al. (2003) for review, especially because it 

may modify our understanding of dichlobenil’s persistence if the study is found to be

acceptable.

Chemtura Comment: “BZZ will not be formed in substantial amounts under real world 

conditions in natural surface waters. As such BZZ should not be considered a residue of 

concern in drinking water; rather it should be classified as an artifact created in clear, sterile 

and buffered solutions irradiated under laboratory conditions.”

Chemtura’s arguments in support of this comment included that:

• Only in one of the four replicates did BZZ reach 19% of the applied in MRID 

41709801; the average concentration at day 21 was 17% of the applied.

• The formation of BZZ showed a significant slowdown, which is an indication it is not 

photolytically stable.

• An unpublished report by Schocken (2003) indicates that:

o Photodegradation in artificial systems (clear, buffered, sterile solutions) is 

overestimated compared to photodegradation in natural surface waters due to 

sunlight attenuation as a function of depth and light scattering in the top layers 

of natural water bodies by macro- and micro-organisms.

o Dichlobenil has a high tendency to escape from water to air due to its high 

vapor pressure.

• MRIDs 41149501, 41306001, and 45539401 and Willems & Hoitink (2004) did not 

show formation of BZZ in natural aquatic systems.

EFED Response: The formation of BZZ in natural surface waters cannot be discounted

because BZZ has not been analyzed for in the field. Field studies should include as analytes 

major degradates identified in laboratory environmental fate studies.

A major degradate is a degradate that forms 10% or more of the applied amount in any single 

replicate, not only as an average concentration. BZZ is a major degradate in MRID 
10

41709801 because it formed up to 19% (i.e., >10%) of the applied in one replicate at study 

termination, with an average concentration of 17% of the applied.

The concentration of BZZ was increasing at study termination for 3 of 4 replicates in MRID 

41709801, which means that the maximum production of BZZ may have exceeded 19% of 

the applied if the study were run longer. The average formation rate of BZZ was slowing 

down at study termination for three of the four replicates, but not for the fourth replicate. 

This may indicate that BZZ does not persist but it is complicated by study variability.

Sunlight attenuation and scattering in natural water bodies is well known. There is 

variability in the natural environment, however, meaning that some natural water bodies are 

deep, opaque, and/or shaded and others are shallow, clear, and not shaded. Greater amounts 

of BZZ would be expected to form in the latter type of water body than in the former. Due to 

the variability in natural water bodies, we cannot predict that BZZ will form in all water 

bodies or that BZZ will not form in any of them.

Vapor pressure is a chemical property useful for predicting volatilization from dry surfaces. 

OCSPP guideline 835.6100 recommends using the Henry’s Law Constant (HLC) to assess 

volatility from water. The HLC for dichlobenil (7.1 × 10-6 atm-m3

/mol at 20°C; USEPA, 

2012a) is equivalent to an air-water partition coefficient (KAW) of 3.0 × 10-4, which places 

the compound in the “slightly volatile from a water surface” class. This means that volatility 

from water is expected to occur at a limited rate, not with a high tendency.

MRIDs 41149501, 41306001, and 45539401 are laboratory studies conducted in the dark, not 

“higher-tiered aquatic studies.” In darkness, formation of the photoproduct BZZ would not 

be expected. Willems & Hoitink (2004) is an unpublished study that has not been submitted 

to the Agency for review. If it was conducted in the dark, then it would not be expected to 

show formation of BZZ. If it was conducted under illumination (either in the laboratory or in 

a shallow, clear, unshaded water body in the field), then it may provide useful information as 

to the formation of BZZ. Unless data are submitted that show otherwise, BZZ is assumed to 

be a potential photoproduct in natural water bodies, not a laboratory artifact, and is 

considered a residue of concern in drinking water.

Chemtura Comment: “As adsorption/desorption coefficients are only relevant to assess the 

mobility of substances found in or on soil, similar studies for an artificial aqueous photolysis 

product (BZZ) are not required.”

EFED Response: Adsorption/desorption coefficients are also relevant to assess the “mobility 

of chemicals and their distribution in...water...as well as for comparative and modeling 

purposes,” to quote Chemtura’s comments. Batch equilibrium data for BZZ are needed for 

understanding its distribution in water and for exposure modeling.

Chemtura Comment: “Chemtura already provided a specific adsorption study for BAM 

(Dzialo, 2001 MRID 45539402) which is still undergoing review.”
11

EFED Response: MRID 45539402 was reviewed as of September 27, 2012 and classified 

acceptable. As such, additional adsorption/desorption data for BAM are not needed.

Chemtura Comment: “Chemtura will provide a further degradation study (Lynn et al, 2003) 

conducted on three additional soils [for dichlobenil].”

EFED Response: If Lynn et al. (2003) is acceptable for risk assessment upon review, then 

additional aerobic soil metabolism data for dichlobenil will not be needed. Otherwise, an 

additional study will be needed. Chemtura is encouraged to submit relevant studies such as 

Lynn et al. (2003) as soon as possible for review.

Chemtura Comment: “Chemtura already provided a specific aerobic aquatic metabolism study 

for BAM (Whitright, R., 2001; MRID 45539401) which is still undergoing review...In 

addition to the referenced study for TGAI (Gohdes 1989, MRID 41149501), an additional 

aerobic aquatic metabolism study in two water/sediment systems, a pond and a river system, 

will be made available which allows further evaluation of the behavior of dichlobenil and 

BAM under aerobic aquatic conditions (Willems H. & Hoitink M., 2004)”

EFED Response: MRID 45539401 was reviewed as of September 27, 2012 and classified 

unacceptable. MRID 41149501 was conducted on dichlobenil and is not sufficient to 

understand the environmental fate of BAM in aerobic aquatic conditions. Therefore 

additional data are needed. If Willems and Hoitink (2004) is acceptable for risk assessment 

upon review, then additional aerobic aquatic metabolism data for BAM will not be needed. 

Otherwise, an additional study will be needed. Chemtura is encouraged to submit relevant 

studies such as Willems and Hoitink (2004) as soon as possible for review.

Chemtura Comment: “In Table 12 [of the Problem Formulation]...it is stated...that Jacobson et 

al (1991, MRID 41780601) did not adequately characterize the sediment...The report 

provides standard measurements of soil and sediment characterization: overall type of 

soil/sediment, pH-value, organic matter content...cation exchange capacity, the bulk density 

and the texture distribution. All of this information provides more than adequate details on 

the characteristics of the sediment. Therefore, Chemtura suggests that the study 

classification should be changed from ‘upgradeable’ to ‘acceptable’.”

EFED Response: MRID 41780601 was conducted in a man-made pond. As Chemtura 

notes, the study provides a sediment characterization. However, the original DER for this 

study says that the “thickness of the recently deposited sediment was not reported, and the 

characteristics of the deeper sediment [i.e., the original soil before the pond was impounded] 

at the test site were not provided.” It is unclear which sediment or soil horizon the sediment 

characterization describes, although it is likely a description of the upper horizon of the 

original soil. While these ambiguities are not resolved, additional information is not 

expected to change the interpretation of the study and is not clearly recommended in OPPTS 

guideline 835.6200. Therefore, the aquatic field dissipation study classification is upgraded 

to “acceptable.”
12

Chemtura Comment: “In the same section a potential need for data was identified for [ECMs 

developed in the 1970s] which were deemed ‘...upgradeable if validated by independent 

laboratories...’ Both of these analytical methods are outdated and more modern analytical 

methods in water are available...Chemtura suggests to only focus the attention on relevant 

modern methods and exclude any analytical method which is considered outdated based on 

modern, analytical requirements.”

“Further, the Memorandum states that the analytical method in MRID 44712701 (Carter 

1998) and 45321801 (Carter 2000) can be upgraded if validation by an independent 

laboratory is made available...[MRID 44712701] was refined and updated by [MRID 

45321801, which was]...then independently validated by Noon (2001). Chemtura will 

provide this independent laboratory validation study.”

EFED Response: The Agency agrees that only the most modern analytical method in water 

(MRID 45321801 by our records) needs independent validation. This is stated in Table 12 

and on page 40 of the problem formulation for registration review. Table 12 pointed out that 

the three older analytical methods in water (MRIDs 38630, 42492, and 44712701) are 

upgradeable if validated by independent validation in an effort to explain the study 

classifications of “upgradeable,” not to request the validation data. The Agency looks 

forward to receiving Noon (2001) for review. If Noon (2001) is found to adequately validate 

MRID 45321801, then no additional validation data will be needed for the analysis of 

dichlobenil and BAM in water.

If an aquatic field dissipation study is conducted in a shallow, clear, unshaded water body to 

investigate the formation of BZZ, then an analytical method in water for BZZ will need to be 

developed and independently validated. Submission of a study protocol is encouraged prior 

to initiating a field study. However, an aquatic field dissipation study is not requested in 

support of registration review.

Chemtura Comment: Table 1 of Chemtura’s comment document indicates that they do not 

intend to conduct four ecotoxicity studies requested by EFED. Chemtura appears to intend to 

submit rationales for use of existing studies on dichlobenil under OCSPP guidelines 

850.1400 and 850.2300. Regarding studies on BZZ under OCSPP guidelines 850.1075 and 

850.4400, Chemtura appears to intend to ask that the data requirements are waived; however, 

explicit waiver requests were not included.

EFED Response: The Agency will consider any formal waiver requests submitted by 

Chemtura. The comment document did not provide formal waiver requests for the four 

ecotoxicity studies that Chemtura appears to intend not to conduct. The arguments presented 

in the comment document that BZZ is not environmentally relevant are insufficient to waive 

the requested ecotoxicity studies on BZZ, even if they are submitted to the Agency in a 

formal waiver request. See the EFED response on page 9 of this document for an 

explanation of why these arguments are insufficient.
13

In order to assess the effects and degradability of dichlobenil residues in wastewater 

treatment facilities, EFED asks that PRD request submission of activated sludge respiration 

inhibition and ready biodegradability studies on dichlobenil (Mead, 2002) and BAM (Van 

der Laan-Straathof and Philips-Van Loo, 1996) that were submitted to the European Union 

and reported in the Draft Assessment Report (DAR) for dichlobenil.

References

Lynn, R., G. McCorquodale, and K. Paterson. 2003. [14C]-Dichlobenil – The Degradation of 

[

14C]-Dichlobenil in Agricultural Soils under Aerobic Conditions. Report No. 22440. 

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