### 5?.*. 2"' 

## n UNITED STATES ENVIRONMENTAL PROTECTIONAGENCY I 

# $&,&; t Washington, D.C. 20460 9 P

4~ f3R0'cG PC Code: 077401 DP Barcode: D255995 MEMORANDUM July 6, 1999 Subject: EFED Risk Assessment for the Reregistration Eligibility Decision or1 the ?-aminoethanol salt of 

### 5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide (Niclosamide) To: Laura Parsons, CRM Susan Lewis, Chief ReregistrationBranch I Special Review and Reregistration Division (7508W)
I I From: Dana Spatz, Chemist Thomas M. Environmental Risk Branch IV Environmental Fate and Effects Division Through: Mah T. Shamim,Ph.D., 

## Ms) 7 

# -6 -7

# 7 EnvironmentalRisk Branch I Environmental Fate and Effects Division

This memo summarizes the EFED environmental risk assessment for niclosamide (Bayer 73@; BayluscideB)reregistration for use against sea lampreys(Petromyzonmarinus). Although application rates are carefully monitored and adjusted to minimize impactto nontarget aquatic organisms,our analysisofthe environmentalfateand ecotoxicityofthis lampricide, indicatesthecurrent applicationrateswill impactnontarget aquatic organisms. When applied in combination with TFM (Lamprecidm), the toxic effects of lampricides are potentiated. The extent of adverse effects in the treatment area depends on streadriver dischargerate, pH, hardness and water temperature. Although niclosamide is likely to havean immediate effect on the aquatic community, the data suggest that treatment area community structure returns to pretreatment conditions within approximately 6 months. Additionally, a genuine effort is made to document where sensitive populations reside and steps are taken to avoid treatments at concentrationsknown to be toxic to these organisms. The long-termeffects tomore sensitive species,e.g., indigenous lampreys, aquatic earthworms and flatworms,andto aquaticcommunitiesdownstream fromthe treatment sites where chronic effects are more likely,remain uncertain. Given the available information, it is reasonable to conclude that the effects of niclosamide on nontarget organisms are likelyto extend beyond the immediatetreatmentarea. Although the chronic effects on nontarget organisms downstream of the application site may be mitigated through dilution of the lampricide(s),these effects can not be characterized in this document due to the lack of data. Additionally the acute toxicity of newer slow-release formulations to sediment-dwelling nontarget organisms can not be characterized. 

## 1

## IllllIUl~ IIIIIIIIIIIIIIIIIIIIlllll1111 2012370*\TED S74p gY 

## n 

# \ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

### w 

# $&&,$ T. Washington, D.C. 20460 <' %% PRoT~G 

### PC Code: 077401 

### DP Barcode: 

### D255995 MEMORANDUM July 6, 1999 Subject: EFED Risk Assessment for the Reregistration Eligibility Decision on the 

### 2-aminoethanol salt of 

### 5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide (Niclosamide) To: Laura Parsons, CRM Susan Lewis, Chief Reregistration Branch I Special Review and Reregistration Division (7508W) From: Dana Spatz, Chemist Thomas M. Steeger, Fishery Biologist Environmental Risk Branch IV Environmental Fate and Effects Division Through: Mah T. Shamim, Ph.D., Chief Environmental Risk Branch IV Environmental Fate and Effects Division

This memo summarizes the EFED environmental risk assessment for niclosamide (Bayer 73@; Bayluscidem) reregistration for use against sea lampreys (Petromyzon marinus). Although applicationrates are carefully monitored and adjusted to minimize impact to nontarget aquatic organisms, our analysis ofthe environmental fate and ecotoxicityofthis lampricide, indicates the currentapplication rates will impact nontarget aquatic organisms. When applied in combination with TFM (Lamprecidm),the toxic effects of lampricides are potentiated. The extent of adverse effects in the treatment area depends on streamlriver discharge rate, pH, hardness and water temperature. Although niclosamide is likely to have an immediate effect on the aquatic community, the data suggest that treatment area community structure returns to pretreatment conditions within approximately 6 months. Additionally, a genuine effort is made to document where sensitive populations reside and steps are taken to avoid treatments at concentrations known to be toxic to these organisms. The long-termeffectstomore sensitive species, e.g., indigenous lampreys, aquatic earthworms and flatworms, and to aquatic communities downstream fromthe treatment sites where chronic effects are'morelikely, remain uncertain. Given the available information, it is reasonable to conclude that the effects of niclosamide on nontarget organisms are likely to extend beyond the immediate treatment area. Although the chronic effects on nontarget organisms downstream of the application site inay be mitigated through dilution of the lampricide(s), these effects can not be characterized in this document due to the lack of data. Additionally the acute toxicity of newer slow-release formulations to sediment-dwelling nontarget organisms can not be characterized.

### Outstanding Data Requirements Environmental Fate: There are insufficient data available to adequately assess the environmental fate of niclosamide. The environmental fate data requirements that havebeen fulfilled are Hydrolysis(16 1 - I), Leaching-AdsorptiodDesorption (163-1) and Accumulation in Fish (165-4). An acceptable photodegradation in water study is needed in order to determine the extent to which niclosamide degrades by photolysis and to identify photoproducts. Acceptable anaerobic and aerobic aquatic metabolism studies are needed in order to assess the metabolic degradative potential ofniclosamide under aquatic conditions. 1. photodegradation in water (Guideline 16 1-2) 2. aerobic aquatic metabolism (Guideline 162-4) 

### 3. anaerobic aquatic metabolism (Guideline 162-3)


### Ecological Effects: Many of the data requirements were addressed through the submission of non-guideline studies that were conducted without GLP protocol. While the chronic effects of niclosarnide in the immediate treatment area may be mitigated through the flushing action of the streadriver, the chronic effects of niclosamide on nontarget organisms downstream and more notably in the mouth oftributaries to the Great Lakes are uncertain. Given the possible acute effects on freshwater fish, the following chronic studies are requested: 

### 4. fish early life stage (Guideline 72-4a) 5. fish full life cycle (Guideline 72-5) Additionally, given niclosamide's potential to adsorb to sediments,theuse of formulations specifically designed to slowly release the chemical at the water-sediment interface, and the acute toxicity of niclosamide to aquatic invertebrates, the following acute study is requested:
6. chironomid sediment toxicity test (Guideline 850.1790) 

### Uncertainties The environmental fate and ecological effects of niclosamide characterized in this report are restricted to the specific treatment site and focuses on the acute toxicity of niclosamide given projected treatment levels selected to survey lampreypopulations andlorachieve

### a sea lampreyLC,, 

# , and nontarget fish LC,,. While the data suggest that treatment areas recover to pre-treatment community structure, certain aquatic species seemparticularly sensitivetothe effectsofniclosamide. Given the persistence of niclosamide, mitigation of its effects relies predominately on the flushing action ofthe streadrivertributaries and eventual deposition and dilution in the Great Lakes. Initial assessments of the ecological effects assumed that niclosamide would not be persistent in thetreatment area and that the eventual deposition of niclosamide into the Great Lakes would render chronic-effect studies unnecessary. While there are data to suggest that niclosamide concentrations within the treatment area quickly diminish to levels below quantitation within 48 hours after application, 

### EFED is uncertain to the degree to which niclosamide concentrations in areas downstreamoftheapplication site are rendered ineffective. As such,thepotential for chronic effects is uncertain particularly in the mixing zones at the confluence of tributaries with the Great Lakes. Additionally, newer formulations of niclosamide that result in its slow release alongthe streamlriver bottom pose an unknown risk in terms of both acute and chronic toxicity to nontarget sedimentdwelling organisms.

### Office of Pnzvention, Pesticides, and Toxic Substances



## Environmental Fate and Ecological Risk Assessment for the Reregistration Eligibility Decision

Niclosamide (2-amino ethanol salt of 

### 5-chloro-~-(2-chloro-4-nitro~hen~l)-2-h~drox~benzamide)

### TABLE OF CONTENTS INTRODUCTION



### ............................................................. 1 USE CHARACTERIZATION



### ....................................................2 ENVIRONMENTAL FATE AND TRANSPORT ASSESSMENT



### .......................4



### .............................................................. Summary 4 

### Chemical Identity and Physicochemical Properties



### .............................. 5 

### Chemical Degradation



### .................................................... 5



### ............................................................... Mobility 6



### ........................................................ Bioaccumulation 7 Fieldstudies



### ............................................................ 7 Aquatic Exposure Assessment



### ..............................................8 ECOLOGICAL EFFECTS HAZARD STATEMENT



### ................................. 8 Summary



### .............................................................. 8 Toxicity to Terrestrial Animals



### .............................................9 Avian Acute Oral 

### ,Subacute Dietary and Chronic



### ........................ 9 Mammals, Acute and Chronic



### .............................................. 9 Insects



### ................................................................. 9 Toxicity to Freshwater Aquatic Organism



### .....................................9 Freshwater Fish, acute, Chronic



### ...................................... 9 

### Freshwater Invertebrates, Acute 

### ,Chronic



### .................................... 10 Toxicity to Estuarine and Marine Organisms



### ................................. 10 Toxicity to plants



### ................................................. 10 ENVIRONMENTAL RISK ASSESSMENT



### ....................................... 10 Exposure and Risk to Non-target Terrestrial Organisms



### ......................... 11 Exposure and Risk to Insects



### .............................................. 11 Exposure and risk to non-target Freshwater Aquatic Organisms



### ...................11



### ...................................................... AcuteFish 11



### ..................................................... Chronicfish 11



### .................................................... AquaticInvertebrates 12



### .......................................................... Acute 12 Plants



### ................................................................ 12 EndangeredSpecies



### ..................................................... 17 ENVIRONMENTAL RISK CHARACTERIZATION



### ................................ 18 Terrestrial



### .............................................................. 19 Aquatic



### .................................................. ; 

### 19



### ............ Application Rate Analysis



### ................................................ 20 Uncertainties



### .......................................................... 21 APPENDIX 1 ECOLOGICAL TOXICITY DATA



### .................................. 23Ecological Toxicity Data



### ................................................. 23 Toxicity to Terrestrial Animals



### ...................................... 23 Birds. Acute and Subacute



### .................................... 23 Mammals. Acute and Chronic



### ....................................... 25 Toxicity to Freshwater Aquatic Animals



### .....................................25 Freshwater Fish. Acute



### ............................................ 25 Effects of Water Quality on Toxicity



### ............................26 Toxicity of TFM:niclosamide mixture



### ...........................27 Freshwater Fish. Chronic



### ........................................... 28 Freshwater Invertebrates. Acute



### ...................................... 28



### .............. Toxicity of TFM and a mixture of Bayer 73 to Aquatic Invertebrates 31 Freshwater Invertebrate. Chronic



### .....................................31 Toxicity to Estuarine and Marine Animals



### ...................................32



### ..................... Estuarine and Marine Organisms. Acute and Chronic 32 Toxicity to Plants



### ....................................................... 32 Aquatic Plants



### ...................................................32 APPENDIX 2



### . EXPOSURE AND RISK CHARACTERIZATION



### .....................34 Exposure and Risk to Nontarget Terrestrial Animals



### ...........................36 Acute Risk Quotients for Avian and Mammalian Species



### .................36



### ......................................................... 36



### ........... Acute Risk Quotients for Avian and Mammalian Species 36 Exposure and Risk to Nontarget Freshwater Aquatic Animals



### .................... 36 Freshwater Fish



### .................................................. 36



### .............................................. Aquatic Invertebrates 38



### ............................... Exposure and Risk to Nontarget Aquatic Plants 39

### INTRODUCTION Niclosamide (2-amino ethanol salt of 

### 5-chloro-N-[2-chloro-4-nitrophenyl]-2- hydroxybenzamide) is a biocide intended to control sea lampreys (Petromyzonmarinus) in streams and rivers tributary to the Great Lakes where these destructive organisms have impacted both the commercial and recreational fishery resources. Niclosamide is a halogenated mononitrobenzamide and is sold under the commercial name Bayluscide'. Bayluscide comes in three formulations, a 5% granular, a 3.2% granular, and a 70% wettable powder. The mode of action of niclosamide has been associated with uncoupling oxidative phosphorylation, respiratory and circulatory collapse and inhibition of ion-uptake. Niclosamide is currently registered for aquatic food and non-food uses. The registrant (U.S. Fish and Wildlife Service)is seekingreregistration for the EPA Product Registration 006704-00087 (70% wettable powder Bayluscidem) and 006704-00091 (3.2% granular Bayluscide). According to the U.S. Fish and Wildlife Service (Johnson and Weisser 1996), ofthe 5,339 streams tributary to the Great Lakes, only 449 (8.4%) are knowntobe or have been infested with sea lampreys. Currently, 150streams (<3% of the total number of tributaries) are treated on a 3 

### - 5year cycle. Between 1991 to 1998, 60 streams out of 426 treated with lampricides were treated with niclosamide mixed with a second lampricide, i. e.,TFM. In 1998, a total of 178,119

### m2(44 surface acres) of strearnslrivers were treated with niclosamide. Of the 30 streamslrivers scheduled for treatment in 1999, four will receive the TFM/niclosamide mixture (pers. comm. Dorance Bregge, Treatment Supervisor, U.S. Fish and Wildlife Service 1999). Lamprey-infested streams are treated if population survey data indicate a sufficiently large number of transformers, 

### i.e., larvae about to metamorphose into their parasitic adult form. As a lampricide, Niclosamide isused totreat only lamprey-infested tributaries to the Great Lakes and not the Great Lakes themselves and it can be applied only by certified applicators of the U.S. Fish and Wildlife Service, the Department of Fisheries and Oceans Canada, and provincial and state fish and game employees. Applicators are required to be familiar with and adhere to the standard operating procedure for lampricide applications (Appendix C). The Great Lakes Fishery Commission has mandated that the reliance on lampricides be reduced by 50%. Through a combination of physical barriers, sterile male release and fine tuning of lampricide applications based onpH, lampricide use has been reducedby 35% compared to levels used in the 1980's. Additionally, the Great Lakes Fishery Commission has projected that by the year 2010, lamprey populations in the Great Lakes shouldbe reducedby 90% in Lake Superior and Lake Huron and that across the Great Lakes the impact of sea lampreys be reduced to better allow for sustained commercial and recreational yields from fish populations (Schleen et al. 1997). To accomplish this task and further reduce chemical reliance, the commission has recommended that additional research be conducted on the use of pheromones to serve as attractants to traps and treatment areas. Additionally, research on the use of the TFMIniclosamidemixture and lampricide formulations that better direct treatments to habitats favored by ammocoetes may help reduce the volume of lampricides required.USE 

### CHARACTERIZATION Historically, niclosamide (Bayluscide 3.2% and 5% granular formulations) has been used alone as a survey method for assessing larval sea lamprey populations and has been used as a molluscicide (Bayluscide 5% granular formulation) in Puerto Rico for the control of snails that vector blood flukes responsible for the potentially debilitating disease Schistosomaisis. In most sea lamprey control applications however, only Trimethylfluoro nitrophenol (TFM) is applied. Occasionally a combination ofTFM and niclosamide (Bayluscide 70% wettable powder) is applied to reduce the amount of TFM required for treatment. The combination is employed where large quantities of TFM would normally be required, such asthe treatment of streams or rivers with high discharge rates. Whenused in combination,theTFM:niclosamideratio ranges from 98:2to 99.5:0.5 (by weight). In practice today, niclosamide concentrations never exceed 50 ppb and the ratio is more commonly 99:l or less (pers. comm. Terry Morse, Treatment Supervisor, U.S. Fish and Wildlife Service 1999). Additionally, with the advent ofthe 3.2% granular formulation, the use of niclosamide as a lamprey control measure has been expanded to treat deep waters where the use of TFM would not be cost effective (pers. comm. Terry Hubert, U. S. Geological Survey Biological Resource Division 1999). Application rates for niclosamide are based on the concentration of lampricide required to to kill 99%ofthe lampreysinthe treatment area. The stream minimum lethal concentration (SMLC) is considered to be the minimum concentration of lampricide(s) needed under specific water chemistry conditions for effective control (99% mortality among sea lamprey larvae during a 9-hr exposure). The stream maximum allowed concentration (MAC) is defined as the concentration of lampricide(s) which may be applied to a stream without causing "undue" nontarget mortality (25% mortality among sensitive fish in a 24-hr period). The objective of any treatment is to maintain lampricide concentrations slightly above the stream minimum lethal concentration throughout the treatment area. Typically concentrations of lampricide are maintained to less than or equal to 1.5 times the stream minimum lethal concentration (Johnson and Weisser 1996) and in practice, lampricide applications are maintained below the LC2, of the most sensitive species (pers. comm. Terry Bills, Fishery Biologist, U.S. Geological Survey Biological Resource Division 1999). By definition, the MAC isthe lethal concentration oflampricide(s)producing 25% mortality among a sensitive salmonid species. However, salmonids may not reflect the most sensitive nontarget species in a proposed treatment area and may only be intermediate in their sensitivity. In these cases, special accommodations are made if nontarget species, known to be more sensitive to niclosamide, are present. These accommodations include reducing the concentration multiple, i.e., to less than a factor of 1.5 the SMLC, or simply deciding not to treat a particular segment of a stream that serves ashabitat for the sensitive nontarget species (pers. comm. Terry Bills, Fishery Biologist, 

### U. S. Geological Survey Biological Resource Division 1999). Furthermore, the use of TFMIniclosamide mixture has been used to selectively reduce the toxicity of certain nontarget organisms that might normally be impacted through the use of the lampricide TFM alone. Application rates to achieve control of sea lamprey while minimizing impact to nontarget organisms are based on stream pH, alltalinit-,temperature, stream discharge, historical treatment data and the results of on-site bioassays involving brown trout (Salmotrutta) and ammocoete larvae.When used as a survey/control method, the 3.2% granular formulation of niclosamide is applied at a rate of 5 lbs a.i. per surface acre of water. Typically, the granules dissolve within 

### 2 to 3 hours and produce a concentration of niclosamide lethal to sea lamprey in the bottom 5 cm of the water column. The objective is to place the granules directly onto the beds the ammocoetes inhabit and thus limit exposure to nontarget organisms;asthe granulesdissolve, niclosamide moves downstream and effectively "blankets" the sediment-water interface (pers. comm. Terry Hubert, U. S. Geological Survey Biological Resource Division 1999). When applied in combination with TFM, niclosamide (70% wettable powder) is first slurried with stream water and the slurry is then mixed with TFM (38% a.i.) in a sump pump; the combined lampricides are then metered via drip feeds or spreader bars using calibrated peristaltic pumps. Application rates and real-time water concentrations are monitored regularly (approximately2times per hour) to assure that water column concentrations are being accurately maintained. Application time is normally for 12 hours, but may be adjusted to assure nine hours of SMLC at downstream sites. 

### A single application cannot be used if the lampricide concentration may decrease to less than the SMLC in areas in need of treatment. In these cases "boost" applications may be located at several locations alongthetreatment area. Lampricide concentrations are measured by spectrophotometry and HPLC within approximately 5 minutes of collection. Normally, niclosamide isused in larger, more eutrophic streamslrivershaving pH range 8.0 

### - 8.6 and high alkalinity and typically, the target concentration in these streams is 25 

### - 35 ppb niclosamide; the maximum treatment concentration is 50 ppb (pers. comm. Terry Bills, Fishery Biologist, 

### U. S. Geological Survey Biological Resource Division, 1999) Combinations of TFMIniclosamide have been used to effectively broaden the differential toxicity between sea lamprey larvae and sensitive nontarget species; while the toxicity of the mix to nontarget species is similarto that of TFM alone,the sensitivity of ammocoete larvae is enhanced by themix (pers. comm. Terry Bills, Fishery Biologist, U.S. Geological Survey Biological Resources Division). The difference in toxicity of the mix to ammocoetes versus sensitive nontargets allows for less TFM to be applied thus reducing potential impacts to nontargets

### ENVIRONMENTAL FATE AND TRANSPORT ASSESSMENT Summary The information in this assessment is based primarily on open literature studies submitted by the registrant to fulfill EPA data requirements. Unless otherwise noted, the data cited here are not from studies conducted according to Subdivision N guidelines, but nonetheless are considered scientifically valid and may be used in assessing the fate and transport of 

### TFM in the environment. Because the open literature studies were not conducted according to the rigorous standards required under SubdivisionN, there is some degree of uncertainty associated with the data, particularly if oneis comparingtheresults ofthese studies to studies for other chemicals conducted according to Subdivision N guidance.
In addition to dilution and dispersion, sorption to sediments and suspended particulates and possibly photodegradation (in clear shallow waters), are the major routes of dissipation of niclosamide. Neither hydrolysis nor volatilization from soil or water surfaces should be major fate processes for this compound.
In most aquatic environments, niclosamide will adsorb to suspended solids and sediment. Though niclosamide does tend to bind to sediments, the binding isby no means irreversible, thus non-target species and benthic organisms in particular, will be exposed to niclosamide for extended periods of time. 

### It is unclear what role, if any, aerobic and anaerobic microbial degradation plays in the dissipation of niclosamide in the aquatic environment. Inthe lake environment, degradation of niclosamide must occur in aprimarily sediment-free system, given the high ratio of water to sediment. As such, niclosamide is expected to remain in solution in the lake system and persist for long periods of time. Based on the bioconcentration factors and the rapid rate of depuration, accumulation in fish is not expected.

### Chemical Identity and Physicochemical Properties Chemical Name IUPAC CAS Registry No. Empirical Formula Molecular Weight Solubility Synonyms Formulated Products Chemical Structure 

### 5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide 1420-04-8

C13H8C12N204 327.13 slightly soluble (230 i50 mg/L) at 25OC; practically insoluble pH 

### > 7.0 niclosamide Bayer 73; Bayluscid

There are insufficient data available to adequately assess the environmental fate of niclosamide. The environmental fatedatarequirements that have been fulfilled are Hydrolysis (161

### - I), 

### Leaching-Adsorption/Desorption (1 63-1) and Accumulation in Fish (1 65-4). An acceptable photodegradation in water study is needed in order to determine the extent to which niclosamide degrades by photolysis and to identi@ photoproducts. Acceptable anaerobic and aerobic aquatic metabolism studies are needed in orderto assessthemetabolic degradative potential of niclosamide under aquatic conditions.
In addition to dilution and dispersion, sorption to sediments and suspended particulates and possibly photodegradation (in clear shallow waters), are the major routes of dissipation of niclosamide. Though niclosamide does tend to bind to sediments, the binding is by no means irreversible, thus non-target species and benthic organisms in particular, will be exposed to niclosamide for extended periods of time. It is unclear what role, if any, aerobic and anaerobic microbial degradation plays in the dissipation of niclosamide in the aquatic environment. 

### Chemical Degradation Niclosamide does not appear to undergo hydrolytic degradation, however it does photodegrade in water. In a supplemental study that addressed both the hydrolysis and aqueous photolysis datarequirements (Schultz and Harman 1978) (MRID 425523 

### 13), [14C]niclosamide did not degrade either in buffered solutions adjusted to pH 5.0,6.9, or 8.7 or in pond water 

### (pH 7.0-7.8) incubated in the dark for up to 56 days. Niclosamide ranged from 

### 93 to 

### 99% of the total radioactivity from each TLC plate in the study. Under photolytic conditions, niclosamide degraded with a half-life of 3.3 days in a pH 6.9 buffered solution that was irradiated by long-wave UV light for up to 14 days. A new photodegradation in water study is needed because, among other deficiencies, degradates were not identified, material balances were not reported, and the output of the light source may not have been comparable with natural sunlight. Therefore, there is a highdegree of uncertainty surrounding the photolysis half-life. However, based on this supplemental study and the UVIvisible spectrum of niclosamide (max. 330 

### nm), it does appear that niclosamide is susceptible to photodegradation inwater and this will be a significant route of dissipation only in clear and shallow water bodies. 

### Mobility
In an acceptable batch equilibrium study (Dawson 

### et al., 1986) (MRID 42552315, 425523 16), it was found that the mobility of niclosamide was'dependent on the pH of the system. Mobility appeared to increase at higher pH's. It should be noted that niclosamide reportedly precipitates from aqueous solutions below pH 6.5.



### Table 

### 1. Average dissociation constants (Kd) for niclosamide at differing 

### pH and sediment

- ~-~ % organic pH 6.5 pH 7.0 pH 8.0 pH 9.0 sediment matter average K, Tahquamenon River 0.9 17 14 5 1 sand Ford River loamy sand Arkansas loam Cedar River sandy 9.0 3 16 loam Under acidic and neutral conditions, niclosamide was not mobile. At pH 8, niclosamide was moderately mobile inthe sand sediment,but not mobile in the other three sediments. In alkaline (pH 

### 9) conditions, niclosamide was very mobile in the sand and moderately to slightly mobile in the loamy sand, loam, and sandy loam sediments. In most aquatic environments, niclosamide will adsorb to suspended solids and sediment. 

### K. Ho and 

### S. Gloss 

### (1987) (MRID 425523 

### 17)conducted a supplemental study to identi@the most probable mechanism for loss of niclosamide from the water column. The results clearly showedthe major route ofdissipation for niclosamide from the water column, excluding dilution or dispersion, is adsorptiontothe sediment. Niclosamide concentrations decreased in the water column at a faster rate in beakers with lake water and sediment exposed to sunlight than in beakers without sediment exposed to sunlight. There was no difference in disappearance rates of niclosamide between light and dark beakers without sediment, indicating that photolysis may not play a major role in the dissipation of niclosamide. After 96 hours, 71% of the niclosamide was still present in beakers with sediment exposed to sunlight, versus 107% in beakers without sediment and 110%in dark beakers without sediment. In a test that eliminated microbial and photolytic processes,niclosamide concentrations decreased faster in sterile dark test tubes with sediment than in sterile dark test tubes without sediment. Ho and Gloss (1 987) also found no difference in disappearance rates of niclosamide among non-sterile light test tubes with sediment, sterile light test tubes with sediment and sterile dark test tubes with sediment. In the presence of sediment, the half-life of niclosamide in the water column was less than 10 days. In the lake environment, degradation of niclosamide must occur in a primarily sediment-free system, given the high ratio of water to sediment. As such, niclosamide is expected to remain in solution in the lake system and persist for long periods of time. Volatilization from dry and moist soil surfaces, or fromwater surfaces should not be a major fate process for this compound. The measured vapor pressure is 9.9 x mm Hg at 25 "C and the estimated Henry's Law constant is 6.5 x 1 0-lo atm-m3/mole. No data have been provided concerning the mobility of niclosamide degradates. However, previous information suggested that aminoniclosamide binds to sediment as well. Since aminoniclosamide is said to be 80-fold less toxic than parent niclosamide, confirmatory mobility data on this degradate is not critically important. Bioaccumulation In a supplemental study (Hubert 1996) (MRID44 12820 I),BCF's were determined to be 49x for edible tissue, 215x for whole fish, and 916x for viscera in rainbow trout. The concentration of radioactive residues in the fish increased very rapidly to a plateau during the first three days of exposure. Depuration was rapid and fairly complete by day 10 ofthe elimination period. There is some degree ofuncertainty surroundingthe results of this study since neithertheradioactivity in the water, nor the accumulated radioactivity in the fish tissues was identified, but was assumed to be parent niclosamide. There is reason for concern that photodegradatesmay have been present in the test tank, particularly since it appears that niclosamide may be susceptible to photolysis and that a small amount of acetone, a photosensitizer, was used as a co-solvent. However, given the stability of niclosamide to hydrolysis at the pH values in the study, and the flow-through design of the experiment, significant degradation of niclosamide in the exposure tank would not be expected. Field Studies 

### K. Ho and S. Gloss (1987) conducted a monitoring study (MRID 425523 17)in Seneca Lake, New York. The purpose ofthe study was to describe the distribution, dispersion, and dissipation of niclosamide in the water column after an application and to assess its bioaccumulation by, and toxicity to, two species of caged, non-target fish. Granular Bayer 73 was applied at a nominal rate of 110 kglha (2300 ug/L, assuming dissolution into the bottom 10cm of water). Niclosamide concentrations inthe lake water samples ranged from 40 to 573ug/L. Concentrations were generally lowest at the surface and highest atthe bottom (0.1m). Although there is anexpectationthatniclosamide isreleased from granules intothe bottom 5 cm of the water column, it was found throughout the water column; a result of eithermixing or premature release. Concentrations greater than 40 ug1L were measured at all depths and stations within the treatment area. After 48 hours, all concentrations were below 30 ug/L. Concentrations were below the detection limit (10 ug/L) by 96 hours after application. Niclosamide residues in fish muscle tissue were consistent with water concentration and distribution patterns. Residues ranged from 

### 0 to 858nglg and were highest in fish from the bottom depth at all stations. Residues increased until 14-24 hours after application and then declined. The selective toxicity of granular niclosamide is based on the assumption that dissolution takes place at the sediment-water interface, implying that non-target fish could escape lethal concentrations whereas ammocoetes,which live in the substrateand are relativelyweak swimmers, would be killed. However, the results of this investigation showthat both lampreys and non-target fish will be exposed to niclosamide throughout the water column. Aquatic Exposure Assessment Since niclosamide is added directly to water, the estimated environmental concentrations (EECs) used in this evaluation were not derived from the GENeric Expected Environmental Concentration Program (GENEEC) but rather were based on projected treatment concentrations derived from when niclosamide is applied with 

### TFM. Application rates for the TFMIniclosamide mixture are based on pH, alkalinity, temperature, strearnlriver discharge rates and bioassay data. Treatment levels of niclosamide have historicallyranged between 25 to 35 ppb (pers. comm. Terry Bills, Fishery Biologist, 

### U. S. Geological SurveyBiological Resource Division 1999); this range of treatment levels was used in the aquatic risk assessment. The maximum treatment level of niclosarnideis 

### 50 ppb and it was used to assessthe toxicity to terrestrial organisms. ECOLOGICAL EFFECTS HAZARD STATEMENT Summary The information in this assessment is based on a combination of both open literature and studies specifically conductedto meet 

### EPA data requirements. While all of the data included in this assessment (Appendix 

### 1) were considered scientifically sound, open literature studies were not subject to the rigorous standards currentlyrequired under Good LaboratoryPractice (GLP) protocols. Given the range of protocols over which the ecotoxicity data were collected, there is some uncertainty over how the toxicity results may have been impacted by this lack of GLP standards. Based on ecological effects data, the toxicity potential of niclosamide can be characterized as follows:

Avian acute- moderately toxic (LD,, 60 mglkg) Avian subacute dietary-practically nontoxic (LC,, > 5,419 mg/kg diet() Mammalian acute- practically nontoxic (LD,, >1,000 mglkg) Fish (freshwater acute)- highly toxic to very highly toxic (LC,, 0.03 

### - 0.23 mg/L)

• Invertebrates (freshwater) acute- slightlyto very highly toxic (EC,, 0.034 - > 50 mg/L)Invertebrates (freshwater) chronic- (NOAEC 0.03 mgIL; LOEC 0.05 mgL) Aquatic plants- toxic (0.04 to > 1,450mg1L) Environmental factors influenced the toxicity ofniclosamide. In general niclosamide was more toxic as pH and water hardness decreased. When niclosamide is used in combination with TFM, the toxicity potential of the combined lampricides was additive.


### Toxicity to Terrestrial Animals Avian Acute Oral,Subacute Dieta y and Chronic The acute oral toxicity data suggest thatniclosamide ranges intoxicityfrombeing moderately toxic to practically nontoxic (LD,, 60 to > 2,000 mglkg) to avian species (MRIDs 436777-01, 436777-02, and44 1 803-01) and practically non-toxic (LC,, >5,419 ppm) ona subacute dietary basis (MRIDs 44 1803-02 and 441 803-03). Avian chronic reproduction studies are not required. The 

### 7 1-1 and 7 1-2 guideline requirements for acute studies have been fulfilled. 

### Mammals, Acute and Chronic Niclosamide waspractically nontoxicto small mammals on an acute oral basis (LD,, > 1,000 mglkg) (MRID 4255223-01). No chronic toxicity data were available. 

### Insects A honey bee acute contact study using the TGAI is not required for niclosamide because its use (aquatic sites) will not result in honey bee exposure. 

### Toxicity to FreshwaterAquatic Organism Fresh water Fish, acute 

### ,Chronic The data indicate that the acute toxicity of niclosamide ranges from being highly toxic to very highly toxic for fieshwater fish species. The most sensitive species tested were the rainbow trout, 

### Onchorhynchusmykiss (LC,, =0.03 mg/L), sealamprey, 

### Petromyzon marinus, (LC,, =0.049 mg/L) and the bluegill sunfish, 

### Lepomis marcrochirus, (LC,, = 0.049 mg/L). The 72-1 freshwater fish acute toxicity requirement (Guideline 72- 1) has been fulfilled (MRID#436793-02,44206 1-01). Because niclosamide is also used in combination with TFM, toxicity tests for the combination of these two chemicals are needed to assess risk. Results of tests specifically conducted to address this issue showthat the channel catfish was the most sensitive species to TFM (LC,, = 0.75 mgIL), niclosamide (LC,, = 0.0125 mg/L) and to the combination of these chemicals (LC,, =0.6 15mg1L). In general, the data showthatthe combination of niclosamide and TFM tended to enhance toxicity. Based on the results of this study the authors concluded that the mixture of TFM:niclosamide was at most additive under various test conditions (Bills and Marking 1976).No data were provided on the chronic toxicity of niclosamide to fish. Thus, guideline 72-4a (fish early life stage) and guideline 72-5 (fish full life cycle) are not fulfilled and represent data gaps. 

### Freshwater Invertebrates,Acute 

## ,Chronic In acute toxicity tests, niclosamide was slightly to very highly toxic to aquatic invertebrates (EC,, range: 0.034 to > 50 mg/L). The acute freshwater invertebrate study requirement (Guideline 72-2) has been fulfilled 

### (MRID# 441 748-04). When TFM is used in combination with niclosamide(98:2 by weight), LC,, values for the mixture ranged from 1.5mg/L (moderately toxic) to greater than 100.0mg/L (practically non-toxic) among freshwater invertebrates. The most tolerant species tested were crayfish, dragonflies, snipeflies, and dobsonflies. The most sensitive species were turbellarians, snails and aquatic earthworms and appeared to affect organisms inhabiting sediments. These data indicate that the mixture of TFM and niclosamide enhanced the toxicity of TFM to aquatic invertebrates. Given niclosamide's potential to adsorb to sediments, the use of formulations specifically designed to slowly release the chemical at the water-sediment interface, and the acute toxicity of niclosamide to aquatic invertebrates, data on sediment toxicity testing using chironomids would be of interest.


### Toxicity to Estuarine and Marine Organisms Because the use of niclosamide is unlikely to directly enter into estuarinelmarine environments, toxicity testing for these species is not required. 

### Toxicity to plants Niclosamide inhibitedthe growth ofaquatic plants; diatoms suffered 50% growth inhibition at concentrations less than 130ppb. Green algae exhibited a considerable range in sensitivityto the effects of niclosamide; EC,, values ranged from 0.41 to 1,450 ppm. The studies submitted for review did not comply with recommended guidelines and were classified as supplemental.



### ENVIRONMENTAL RISK ASSESSMENT
In order to evaluate th6 potential risk to aquatic and terrestrial organisms from the use of niclosamide, risk quotients (RQs) are calculated from the ratio of estimated envifonmental concentrations (EECs) to ecotoxicity values (Appendix 2 ). These RQs are then compared to levels of concern 

### (LOC) criteria that is used by 

### OPP in the determination of potential risk to nontarget organisms and the resulting need for possible regulatory action Based on application rates and past use history it has been determined that typical EECs fromthe use of niclosamide will range from 25 to 35 ppm. All risk quotient calculations will be based on these EECs.

### Exposure and Risk to Non-target Terrestrial Organisms Niclosamide is only registered for use on aquatic sites. Therefore, the typical terrestrial analysis of risk, based on exposures developed by Hoerger and Kenega (1972) and as modified by Fletcher et al. (1994) is not applicablefor establishing therisk of niclosamide to non-target terrestrial species. However, because numerous avian, i.e., waterfowland shorebirds,and mammalian species (muskrats, beavers, raccoons and numerous other small mammals) typically utilize aquatic environments as nesting and/or feeding habitats and may be exposed to niclosamide via contaminated water, it is appropriate to use the aquaticEECs for conducting the risk assessment to terrestrial species. Calculated acuteRQs show that there 

### is virtuallyno acute

### risktobirds ormammals from the use of niclosamide (RQ 

### < 0.01). RQs for chronic exposure were not calculated. 

### Exposure and Risk to Insects Currently

### EFED does not assessrisk to non-target insects. Results of acceptable studies are used for recommending appropriate label precautions. 

### Exposure and risk to non-target Freshwater Aquatic Organisms. 

### Acute Fish RQ values based on 96-hr LC,, values and predicted treatment levels of 25 ppb and 35 ppb 

### (Figure 1) exceeded acutehigh risk levels of concern. Acute high risk LOCs were exceeded for sea lamprey and rainbow trout at a treatment level of 25 ppb; at 35 ppb, acute high risk LOCs were exceeded for the majority 

### (60%) of the species tested. RQs for the mixture of TFMIniclosamide (98:2 by weight), based on treatment concentrationsof 25 ppb and 35ppb 

### (Figure2) indicate that acutehigh risk LOCs are exceededfor all of the fish tested. RQ values were examined over a range of pH (6.5 - 9.5) for rainbow trout and were based on treatment concentrations of 

### 25 and 

### 35 ppb 

### (Figure 3). The data indicate that as water becomes more acidic, the risk to fish increasesby roughly a factor of 10. 

### Chronic 

### fish
No chronic toxicity data were available for fish.Aquatic Invertebrates 

### Acute Aquatic acute high risk, acute restricted use, and endangered species LOCs are exceededfor aquatic invertebrates at the typical use rates of niclosamide (Figure 4). Acute high risk LOCs are exceeded for aquatic earthworms and flatworms. Aquatic invertebrate 

### RQ values for the mixture of TFM and niclosamide at the minimum predicted concentration of 0.7ppm, range from 0.03 to 0.46,while RQs for the maximum predicted treatment concentration of 2.2 ppm range from 0.08 to 1.47. Acute restricted use and endangered species LOC are exceeded for aquatic invertebratesat minimum predicted treatment concentrations for waters ofpH 7.2 - 7.6. The data indicate that of the species tested, flatworms are at the greatest risk from the use of mixture of TFM and niclosamide to control the sea lamprey. Data suggest that aquatic invertebrates feeding on bottom sedimentsare more likely to be at risk to TFMIniclosamide treatments and may be a result of ingestion of TFMIniclosamide bound to detritus. The TFMIniclosarnide mixture results in higher toxicity to aquatic invertebrates; however, the increase in toxicity is not proportionalto that of the lamprey. In other words, lampreysundergo a marked increase in toxicity to the TFMIniclosamidecomparedto the relatively small increase in sensitivity exhibited by aquatic invertebrates. This differential toxicity between sea lamprey larvae and nontarget aquatic invertebrates as a result of using the TFMIniclosamidemix is exploited to enhance mortality of ammocoetes while reducing effects on nontargets (pers. comm. Terry Bills, Fishery Biologist, U.S. Geological Survey 

### 1999). Plants No acute levels ofconcernwere exceeded for the aquatic plant species tested. At the typical maximum treatment rate of 

### 35ppb for niclosamide,green algae were the most sensitive with anRQ of 0.85.

## 1.4 

# , 1 Rainbow trout 

# 1 1 

# 1

A Bluegill sunfish 

# 1 1.21 

# / Sea lamprey 

# I

Green sunfish



## Treatment Level (ppb) I cute hlgh rlsk vel of concern



### Figure 

### 1. Acute risk quotients (RQ) for freshwater fish based on 96-hr 

### LC,, values and niclosamide treatment levels of 

### 25 and 

### 35 ppb. 

## 0.4 A

## 3.5 Yellow perch 

## TFM:Niclosamide (98:2 by 

## weight)

33 

# '

* Rainbow trout 

## 41

0.5 

# 1

@ Acute high risk Channel catfish



## 0.6 0.8 

## 1 1.2 1.4 

## 1.6 1.8 

## 2 

## 2.2 Predicted TFM Treatment Level 

## (ppm) - -



### Figure 2.. Acute freshwater fish risk quotients

### (RQ)forniclosamide treatment levelsof25 ppb and 35 ppb when used in combination with trifluoromethyl nitrophenol 

### (TFM) (98:2 by weight). level ofconcern.

### Figure 3. 

### Acute freshwater fish risk quotients for rainbow trout 

### (Oncorhynchusmykiss)for niclosamide treatment levels of 25 

### ppb and 35 

### ppb at various pH levels.Species * Water flea Scud Sail Glass shrimp Clam Crayfish M~dge Leech * Aquatlc earthworm Flatworm

Acute high risk level of concern



## 25 30 

## 35 NiclosamideTreatment Level (ppb) Figure 4. Acute invertebrate risk quotients (RQ) based on 96-hr LC,, values at niclosamide treatment levels of 

### 25 ppb and 

### 35 ppb.Endangered Species The endangered species LOC is exceeded for fish and aquatic invertebrates. Limitations in the use of niclosamide may be required to protect endangered species and threatened species, but these limitations have not been defined and may be site specific. The U.S. Fish and Wildlife Service's lamprey control program routinely engages in Section 

### 7 consultations when endangeredlthreatened species are suspected to be present in treatment areas and the U. S. Fish and Wildlife Service is expected to modify their use of niclosamide in accordance with these Section 

### 7 consultations. Historically, the 

### U. S. Fish and Wildlife Service has modified its application procedures to protect nontarget species. If endangeredor threatened species were known to inhabit projected treatment sites, treatment concentrations of the lampricides wouldbe adjusted to minimize impact to these species. Adjustments would include the use of TFMIniclosamidemix to broaden the differential toxicity of the lampricides and thus increase toxicity to sea lamprey larvae while holding the toxicity to nontarget species relatively constant (pers. comm. Terry Bills, Fishery Biologist, U.S. Geological Survey Biological Resource Division 1999; Bills et al. 1985). Additionally, the use of the 

### 3.2%granular formulationhas better directedthe chemical to areaslikely to harbor the ammocoete larvae. According to the U.S.Fish and Wildlife Service (pers. commTerry Morse, Treatment Supervisor, 

### U.S. Fish and Wildlife Service 1999), if treatment concentrations could not be adjusted to minimize impact to sensitivenontarget species, then the identified habitats would not be subjected to lampricide use.

### ENVIRONMENTAL 

### RISK CHARACTERIZATION Estimated environmental concentrations used in this evaluation were based on typical treatment concentrations reported by U.S. Fish and Wildlife Service (pers. comm. Terry Bills, Fishery Biologist,

### U. S.Geological Survey Biological Resource Division 1999) that ranged from 25 

### - 35ppb. At the current treatment levels, acute high risk, acute restricted use and endangered species LOCs are exceeded. Use of the TFMIniclosamide mixture results in larger exceedences of the LOCs; however, the mixture tends to exhibit a marked increase in toxicity to sea lamprey larvae while nontarget organisms exhibit only amoderate increase. Although niclosamide islikelyto have an immediate effect on the aquatic community, the data suggest that treatment area community structure returns to pre-treatment conditions within approximately 6 months. Additionally, a genuine effort is made to document where sensitive populations reside and steps are undertaken to avoid treatments at concentrations known to be toxic to these organisms. The long-term effects to more sensitive species, e. 

### g., indigenous lampreys, andto aquatic communities downstream from the treatment sites where chronic effects are more likely, remain uncertain Because of the nature of the use of niclosamide, i.e.,applied to flowing water, it is difficult to characterize the magnitude ofthe ecological effects associated with use ofthe chemical. Aquatic organisms in the treatment area are expected to be impacted to some extent during the proposed 12- hr treatments. Impacts to aquatic communities in terms of food-web structure are unknown.
In addition to dilution and dispersion, sorption to sediments and suspended particulates and possibly photodegradation (in clear shallow waters), are the major routes of dissipation of niclosamide. Neither hydrolysis nor volatilization from soil or water surfaces should be major fate processes for this compound. In most aquatic environments, niclosamide will adsorb to suspended solids and sediment. Though niclosamide doestend to bind to sediments, the binding isby no means irreversible, thus non-target species and benthic organisms in particular, will be exposed to niclosamide for extended periods of time. It is unclear what role, if any, aerobic and anaerobic microbial degradation plays in the dissipation of niclosamide in the aquatic environment.
In the lake environment, degradation of niclosamide must occur in aprimarily sediment-free system, given the high ratio of water to sediment and the lack of sediments containing appreciable amounts of organic material (Thingvold, 1975). As such, niclosamide is expected to remain in solution in the lake system and persist for long periods of time. Although niclosamide is not expected to bioaccumulate in aquatic organisms, two potential exposure scenarios exist. Aquatic animals may be directly exposedto lampricide in the water as the chemical block moves through during roughly a 

### 24-hrperiod. Additionally, predatory animals may be exposed through the consumption ofprey incapacitated by larnpricide treaments. However, in a study involving the common tern (Sterna hirundo), a shore bird listed asanendangered species in Michigan, the bird would have to consume roughly 16.8 times its body weight in contaminated ammocoete larvae to approach toxic levels (Hubert et al. 1999). Although the immediate effects of niclosamide will likely impact streadriver community structure in the short term, data suggest that treated sites recolonize to pre-event structure within 6months of treatment. This recovery is site specific and may take much longer in certain environments and certain species may be significantly impacted, most notably the indigenous lamprey speciesthat maypopulate treatment areas. In general however, native lamprey species have tended to populate the upper reaches of tributary streams whereas the sea lamprey is more likely to inhabit areas immediately adjacent to strearnlrivermouth. Inpractice, the species distribution of sea lamprey and native species is documented prior to each treatment and lampricide applications are designed to avoid native populations of lamprey. Thus, nontarget species that may have been affected in the treatment area are repopulated through downstream migration from untreated areas. Itisbelieved that, given the current application rates, the effects of niclosamide are mitigated solely by the flushing action through the treatment site. Effects on the aquatic environment downstream from the treatment site are unknown and would depend heavily on the strearnlriver discharge rate, water temperature, pH and alkalinity and the proximity of sensitive nontarget organisms. While treatment areas have demonstrated a capacity to recover, the downstream acute and chronic effects, where niclosamide is most likely to be deposited, remain uncertain. 

### Terrestrial Niclosamide is only registered for use on aquatic sites. However, because numerous avian (i.e.,waterfowl and shorebirds)andmammalian species (muskrats, beavers, raccoons and numerous other small mammals) typically utilize aquatic environments as nesting and/or feeding habitats, and may be exposed to niclosamide via contaminated water, there is some potential for risk to terrestrial species. Additionally, the aerial application of the 

### 3.2% granular formulation may serve as a route of exposure to nontarget terrestrial organisms. Based on the available toxicity data there is very little risk from either acute oral, acute dermal or subacute dietary exposure to mammals or birds. Acute RQs for both birds and mammals (0.00) show that there is no risk from even the maximum permissible concentration (i.e., 50 ppm) from the use of niclosamide. In addition, duringthe nearly fortyyears of niclosamide use to control or survey for the sea lamprey, there are no actual field reports documenting any acute mortality to avian or mammalian species. There are no chronic toxicity data available for avian species. However, because of the very low levels of exposure and the relatively short time that terrestrial species will be exposed, chronic risk to terrestrial species is expected to be very low. 

### Aquatic Based on the available data, of all of the water quality parameters investigated, pH had the greatest influence on the toxicity of niclosamide to most aquatic organisms. At low pH, the free phenol state of niclosamide is practically insoluble in water and thus its use is limited to more alkaline waters.The effects of niclosamide on non-target aquatic invertebrates from sea lamprey control operations have been reported (Gilderhus, 

### 1979). Although niclosamide treatment reduced the total number of aquatic invertebrates by 56% inthe first 7 days after treatment, this effect was transitory. Although use history data suggest that the application ofTFM to control the sealamprey causesvery little impact to most non-target fish, aquatic invertebrates and plant species, some effects to these species will undoubtedly occur. Although use history data suggest that the application ofniclosamide to monitor and control the sea lamprey causes little impact to most non-target fish, aquatic invertebrates and plant species, some effects to these species will undoubtedly occur. Newer formulations of niclosamide that result in its slow release along the streamlriver bottom pose an unknown risk in terms of both acute and chronic toxicity to nontarget sediment-dwelling organisms. Additionally, the lack offieldincident data should not be interpreted to mean that nontarget mortality did not occur but rather that no incidents have been reported. Where adverse effects to certain species and/or taxa have been observed, the evidence suggests that these effects are only transitory and do not threaten any populations of aquatic species. Although there have been some cases where recolonization of affected populations have taken up to 6 or 

### 7 months, most streams recovered to pretreatment levels in a matter of days or several weeks. Recolonization of the treated areas usually occurs from untreated, up-stream portions ofthe tributary although some recolonization occurs from sediments that were too deep to be contaminated by treatment.. The ultimate effect that niclosamide will have on both thepest species and non-target species is primarily due to the pH and hardness of the treated water. Niclosamide treatments, at any concentration, i.e. 

### 25 to 35 ppb and above, would be considerably more toxic under acidic conditions. However, niclosamide use is generally confined to more alkaline streams/rivers and under acidic conditions the toxicity ofniclosamide is limitedby the low solubility ofitsneutral form. Finally, it is apparent that niclosamde may adversely affect certain endangered and/or threatened species if they are exposed to niclosarnide. As such, special label directions and use precautions must be developed and added to the current label to prevent exposure to these species. Application Rate Analysis Decisions regarding application rates and times are based on both abiotic and biotic factors including pH, stream discharge, time of day, temperature, total alkalinity, in-field bioassays and population assessment data. Spreadsheet-based models based on the aforementioned factors have been developed to assist in determining application rates; the inter-relationship of the model input parameters is based on historical data collected from previous applications to specific streams and as such these predictive models are stream specific. While not all treatment sites have these predictive tools, on those systems undergoing marked diurnal fluctuations in pH or because of morphoedaphic reasons represent a complex scenario, the use of these models permits greater latitude in examining possible effects of input parameters on treatment concentrations and start times. Predicted treatment concentrations based on physico-chemical data are then modified based on in-field flow-through bioassays used to establish the site-specific LC,, 

# , for sea lamprey larvae and the LC,, for brown trout. In Lake Superior and upper Lake Michigan, streams tend to have softwater with pH less than 8.2 and thus require lower application rates and are less likely to be candidates for niclosamide treatment. In the lower tier of the Great Lake, tributaries harboring lamprey may exhibit hardnesses exceeding 200 ppm with a pH range 8.1 

### - 8.7. These streams tend to have greater diurnal pH fluctuations and require that lampricide applicationsbe adjustedto reflect changing pH. Typically however, diurnal pH fluctuations do not dramatically affect initial target concentrations and lampricide concentrations remain primarily based on the lower estimate of pH because of the increased toxicity potential of the lampricide at lower pH. Niclosamide target concentrations in hard water streams have ranged from 25 to 35 ppb; however, treatment concentrations are not permitted to exceed 50 ppb (pers. comm. Dorance Brege, U.S. Fish and Wildlife Service Treatment Supervisor 1999). Uncertainties The environmental fate and ecological effects of niclosamde characterized in this report are restricted to the specific treatment site and focus on the acute toxicity of niclosamide given projected treatment levels selected to achieve a sea lamprey LC,, 

# ,and nontarget fish LC2,. Given the persistence of niclosamide, mitigation of its effects relies predominately on the flushing action of the streadriver tributaries and eventual deposition and dilution in the Great lakes. Initial assessments of the ecological effects assumed that niclosamide would not be persistent in the treatment area and that the eventual deposition of niclosamde into the Great Lakes would render chronic-effect studies unnecessary. However, EFED is uncertain to the degree to which treatment site concentrations ofniclosamde are rendered ineffective. As such the potential for chronic effects is uncertain particularly in the mixing zones at the confluence of tributaries with the Great Lakes. While the data suggest that treatment areas recover to pre-treatment community structure, certain species seem particularly sensitive to the effects of niclosamide and may not recover. While the direct effects of niclosamide treatments have been partially characterized, the secondary effects on food chains and the ability of nontarget species to feed during the recovery period is uncertain. Although the ecological data gaps identified in this document may address uncertainties over potential chronic effects,the environmental fate of niclosamide downstream of application sites, i.e., the stredriverdeltas is uncertain without monitoring studiesto quantify niclosamide concentrations in the mixing zones. Additionally, newer formulations of niclosamide thatresult inits slowrelease along the streadriver bottom pose an unknown risk in terms of both acute and chronic toxicity to nontarget sediment-dwelling organisms. 

### BIBLIOGRAPHY Bills, T. 

### D. and L. L. Marking. 1976. Toxicity of 

### 3-trifluoromethyl-4-nitrophenol (TFM), 2',5- 

### Dichloro-4'-nitrosalicylanide (Bayer

### 73), and 98.2 Mixture to Fingerlings of Seven Fish Speciesand to Eggs and Fry of Coho Salmon. US Fish and Wildlife Service, Investigations in Fish Control No.69 .pgs 

### 1-9. Dawson, V. 1986. Adsorption-Desorption of [14C]-Bayer 73 by Bottom Sediments. Final Report No. BST-83-977.05. Unpublished study performed by the U.S. Fish and Wildlife Service, National Fisheries Research Center, La Crosse, WI, and the U.S. Fish and Wildlife Service, Marquette

### Biological Station, Marquette, MI; and submitted by the U.S. Fish and Wildlife Service, National Fisheries Research Center, La Crosse, WI. MRID 425523 16. Dawson, V., D. Johnson and J. Allen. 1986. Loss of Lampricides by Adsorption on Bottom Sediments. Can. J. Fish. Aquat. Sci., 43: 1515-1520. MRID 425523 15. Gilderhus,P. A. 1979. Effects of granular 2',5-dichloro-4'-nitrosalicylanilide (Bayer 73) on benthic macroinvertebrates in a lake environment. Great Lakes Fishery Commission Technical Report 34 :ppl-11. Ho, K. and S. Gloss. 1987. Distribution and 

### Persistence of the Lampricide Bayer 73 Following a Control Application. Can.

### J.Fish. Aquat. Sci.,Vol44,pp. 1 12-1 19. Performedby Cooperative Fish and Wildlife Research Unit, Dept. of Natural Resources, Cornell University. MRID 425523 17. Hubert, T. 1996. Accumulation of the Lampricide Niclosamide by Rainbow Trout: Pilot Study. Unpublished study performed by Upper Mississippi Science Center, NBS, La Crosse, Wisconsin. Submitted by National Biological Service, United States Department of the Interior. MRID 44128201. Hubert, T. D., M. A. Boogaard, T. A. Morse, T. 

### D. Bills, D. A. Johnson, and 

### L. P. Scheen. 1999. Determination ofniclosamide concentrations in sea lamprey ammocoetes following acute exposure to tow formulations of Bayluscide. Project completion report submitted to the Executive Secretary, Great Lakes Fishery Commission, Ann Arbor, Michigan. Johnson, D. 

### A. and 

### J. W. Weisser. 1996. Field toxicity data regarding exposure levels and effects of TFM and Niclosamide on fish and aquatic invertebrates. Upper Mississippi Science Center, National Biological Service. Maki, A.W., 

### L. Geissel. and H. E. Johnson. 1975. Toxicity of the lampricides 3-trifluoromethyl-4- nitrophenol (TFM) to 10 species of algae. U.S. Fish and Wildlife Serv., Invest, Fish Control 56:3- 17. Marking, L.L., and L. 

### E. Olson. 1975 Toxicity of the lampricides 3-trifluoromethyl-4-nitrophenol 

### to non-target fish in static tests. U.S. Fish Wildl. Serv., Invest. Fish Control 60: 3-27. NRCC. 1985. TFM and Bayer 73 in the Aquatic Environment. Envir. Sec. Publ. NRCC 22488, Otawa, Ontario, 203 pp. Schultz, D. and P. Harrnan. 1978. Hydrolysis and Photolysis of the Lampricide 2',5-dichloro-4'- nitrosalicylanilide (Bayer 73). U.S. Departmentofthe Interior, Fish and Wildlife Service Report No. 85. MRID 42552313. Thingvold, D. and G. Lee. 1988. Persistence of TFM in Aquatic Environments. Environmental Science and Technology, vol. 15, no. 11,p. 1335-1340. MRID 425518-07.

### APPENDIX 1 

### ECOLOGICAL TOXICITY DATA Ecological Toxicity Data Toxicity to TerrestrialAnimals 

### Birds, Acute and Subacute An acute oral toxicity study using the technical grade of the active ingredient (TGAI) is required to establish the toxicity of niclosamide to birds. Thepreferred test species is either mallard duck (a waterfowl) or bobwhite quail 

### (an upland gamebird). The LD,, ranged from 532 mgkg to greater than 2,000 mglkg in mallard ducks and based on these data niclosamide is categorized as slightly toxic to avian species on an acute oral basis 

### (Table 1). In the Hudson (1979) study, niclosamid produced intoxication in all ofthe speciestested (mallard ducks, bobwhite quail and ringbilled gulls) at all of the oral-dosage levels administered. Signs of toxicity observed in mallards included tenseness of the masseter, regurgitation, excessive drinking and sitting, imperturbability, incoordination, imbalance,rapid and laboredbreathing, tremors,and temporary whole-bodyrigidity. However, current guideline (71-1) requirements were not fulfilled by the Hudson study since technical grade active ingredient was not used, exposure concentrations were not reported, and no raw data were provided. In the Palmer (1996) study, they failed to establish that the toxicity was greater than 2,000 mglkg. While regurgitation was problematic in doses greater than 532 mglkg, the study failed to note any signs of toxicity that had been reported in previous studies. Thus, it is difficult to reconcile the results from these two studies Supplemental data were provided through an acute oral toxicity studyofredwingblackbirds 

### Agelaius phoeniceus (Schafer 1982;MRID 436777-0 1;this study was classified as supplemental since neither mallard ducks nor bobwhite quail were tested, the purity of the test substance was not specified, appropriate controls were not reported, and specific methodologies were not provided in the report. The estimated LD50 was 60 mg and based on this estimate, niclosamide is classified as moderately toxic to birds. Although the none ofthe studies meet all of the current 71-1 guidelines, no additional acute oral toxicity studies are required at this time and in general niclosamide is classified as being moderately toxic to birds.Table 

### 1. Avian acute oral toxicity of niclosamide in northern bobwhite quail 

### (Colinus

Species % ai LD~o Toxicity Category MRID No. Study (mglkg) AuthorIYear Classification' Northern bobwhite quail 70% >2,000 practically nontoxic 436777-02

(Colinus virginianus) Hudson 1979 supplemental
436777-01 Redwing blackbird -- 60 mglkg Schafer, Bowles, (Agelaius phoenlceus) moderately toxlc and Hurlbut supplemental 1983 436777-02 70% >2,000 practically nontoxic Hudson 1979 supplemental Mallard duck (Anas platyrhynchos) 441803-01 100% 532 slightly toxic supplemental Palmer and

Beavers 

### ' Core (study satisfies guideline). Supplemental (study is scientifically sound, but does not satisfy guideline) Two subacute dietary studies using the TGAI are required to establish the toxicity of niclosamidetobirds. The preferred test speciesare mallard duck andbobwhite quail. Since the 

### LC,, falls in the range >5,000 ppm (Table2),niclosamideis categorizedaspractically nontoxicto avian species on a subacute dietary basis. The guideline

### (71-2) is fulfilled (MRID

### 441803-02and 441803- 03). Table 

### 2. Subacute avian dietary toxicity of niclosamide to northern bobwhite quail 

### (Colinus

- 

### virginianus) and mallard ducks 

### (Anas platyrhynchos) Species % ai 5-Day LC,, Toxicity Category MRID No. Study (PP~)' AuthorIYear Classification 441803-02 Northern bobwhite quail 100% >5,419 practically nontoxic Palmer and

(Colinus virginianus) Beavers Core 1996 441803-03 Mallard duck 100% >5,648 practically nontoxic Palmer and (Anas platyrhynchos) Beavers Core 1996

In studies involvingTFM:niclosamide(98:2)mixtures, the combination resulted in toxicity values that were similar to when TFM was the single active ingredient (Table 

### 3).Table 3. Acute Oral Toxicity of a mixture of TFM and niclosamide (98:2 by weight) to avian species. Species %a.i. LD50 MRID Toxicity category (TFM) mglkg lauthorlyear Mallard duck 96 472 160000/ moderately-toxic (Anas platyrhynchos) Hudson, 1979

Ring-billed gull 35 154 1600001 moderately-toxic (Larus delawarensis) Hudson, 1979


### Mammals, Acute and Chronic Wild mammal testing is required on a case-by-case basis, depending on the results of lower tier laboratory mammalian studies, intended use pattern and pertinent environmental fate characteristics. In most cases, rat or mouse toxicity values obtained from the Agency's Health Effects Division (HED) substitute for wild mammal testing. Ofthe six mammalian acute toxicity studies reviewed by HED, two (Guidelines 8 1-5 and 8

### 1-6) were listed as acceptable (Table 

### 4). Guideline 8 1-3 was classified as inadequate and Guidelines 8 1 

### - 1,81-2, and 

### 8 1-4 were classified as unacceptable.
Table 4. Acute mammalian toxicity of Niclosamid to the Norway rat (Ruttiis norvegicus) (NS = not specified). Species1 Test Toxicity Affected Study Duration % ai Type Value Endpoints MRID No. laboratory rat (Rattus norvegicus) NS Acute oral Rat LD,, > 1,000 mglkg no mortality or 4255223-01 clinical signs rabbit NS Acute dermal LD,, > 2,000 mglkg no mortality or 4255223-01 clinical signs

In HED's assessment of the acute and subchronic mammalian toxicity, no definitive conclusions were drawn from the data other than to note that the available studies do not satisfy eitherthe acute or subchronic toxicity testing requirements for niclosamide. In general, niclosamide treatment did not appearto result in any treatment-related deaths or signs oftoxicity; however, given the classification of the mammalian toxicity studies, there is a large degree of uncertainty in ascertaining the mammalian toxicity.
Toxicity to Freshwater Aquatic Animals 

### Freshwater Fish, Acute Two freshwater fish toxicity studies using the 

### TGAI are required to establish the toxicity of niclosamide to fish. The preferred test species are rainbow trout (a coldwater fish) and bluegill sunfish (a warmwater fish). Results (Table 5) indicate that rainbow trout appeared to be an order of magnitude more sensitive to the effects of niclosamide than werebluegill sunfish and that rainbow trout and sea lamprey were equally sensitive to the effects of niclosamide. Since the 

### LC,, falls intherange of <0.1 ppm, niclosamide iscategorized as very highly toxic to fieshwater fish on an acute basis. The guideline (72-1) is fulfilled 

### (MRID 436793-02).
Table 5. Freshwater fish acute toxicity ofniclosamide to the rainbow trout (Oncorhynchusmykiss) and bluegill sunfish (Lepomis macrochirus) and sea lamprey (Petromyzonmarinus). Species1 96-hour % ai Toxicity LC*,, (PP~) MRID No. Study Flow-through or Static (measuredlnominal) Category AuthorNear Classification

Rainbow trout static 436793-01 very highly Marking and Hogan supplemental toxic 1967 Rainbow trout static very highly 436793-03 toxic Bills and Marking supplemental 1976 Rainbow trout static 436793-04 very Dawson et al. 1976 supplemental toxic
436793-06 Rainbow trout 70% 0.14 highly toxic Rye and King Supplemental 1976 Bluegill sunfish very highly 436793-01 toxic Marking and Hogan supplemental 1967 Bluegill sunfish highly toxic 436793-02 Farringer 1972 core Bluegill sunfish 436793-03 NS 0.152 highly toxic

. Bills and Marking supplemental 1976 Bluegill sunfish 442061-011441748-01 highly toxic Drottar and Swigert core

Sea lamprey 0.049 (nominal) very highly 436793-06 toxic Rye and King Supplemental 1976 Carp 436793-02 (Cyprinus carpio) 99% 0.120ppm highly toxic J. E. Farringer Supplemental 1972
Green sunfish 436793-02 (Lepornis cyanellus) 99% 0.170 ppm highly toxic J. E. Farringer Supplemental 1972 Effects of Water Quality on Toxicity Water quality affected the toxicity ofniclosamide. Table

### 6 illustrates the effect ofpH onthe toxicity of niclosamide to rainbow trout. Trout were roughly 7-times more sensitive to niclosamide at pH 6.5 than they were at pH 

### 9.5. The data emphasize that with decreasing pH (increasing aciditity)thetoxicity of niclosamideto fish increases. Additionally, increasing alkalinity decreased the toxicity of niclosamide (Table 7).Table 6. Comparison of 96-hr LC,, estimates for rainbow trout treated with niclosamide using differing pH at 120C amd water hardness Of 44 mg/L as CaCO, (NRCC 1985). PH 96-hr LC,, 6.5 0.0261 (0.0197 - 0.0345)

Table 7. Comparison ofLC,, estimates for carp(Cyprinuscarpio)and green sunfish (Lepomiscyanellus) treated with niclosarnide using diffehng water hardness.
hardness (mgll as CaCO,) carp green sunfish 96-hr LC;, 96-hr LC,,

Toxicity of TFM:niclosamide mixture.
TFM is used with niclosamide under different situations and environmental conditions to obtain control of the sea lamprey. As such, it has been determined that data on the interaction of these two pesticides are required to establish the toxicity of TFM to freshwater fish species when used in conjunction with niclosamide. Toxicity estimates for the TFMIniclosamide (98:2) mixture are presented in Table 

### 8. The toxicity of TFM was 20 to 50% greater with the addition of niclosamide. In general,the data showthat themixture ofTFM:niclosamidewas additive in toxicity to fish under various test conditions (Maki, 1975). The increased sensitivity of channel catfish to the lampricide TFM relative to the sunfish is reflective of differences in the ability of catfish to conjugate and eliminate TFM. Similar to the sea lamprey, channel catfish have a less efficient glucuronidation mechanism than the sunfish (Kane et al. 1994). The sea lamprey's ability to biotransform TFM is relatively low and channel catfish exhibit an intermediate ability to biotransform TFM compared to the centrarchids and perches.Table 8. Toxicity of TFM/niclosamide (98:2), based on a.i., to seven species of fish in soft water at 12°C. Species 96-hr. LC50 96-hr. LC,, Combination MRIDI Toxicity category TFM Bayer73 Toxic~ty AuthorIYr. (PP~) (ppm) (PP~) Brown trout 0.94 0.02 0.98 Bills&Marking highly toxic 1976 Rainbow trout 1.81 0.0237 1.16 Bills&Marking moderately toxic 1976 Rainbow trout 1.6 441869-021 moderately toxic Drottar&Swigert/ 1996 Lake trout 1.78 0.0284 1.39 Bills&Marking moderately toxic 1976 Brook trout

Channel catfish 0.0237 1.16 Bills&Marking moderately toxic 1976 highly toxic
Bluegill 4.89 0.0636 3.18 Bills&Marking moderately toxic 1976 Bluegill 7.3 441869-01 moderately toxic Drottar&Swigert 11996 Yellow perch 1.71 0.0184 0.9 Bills&Marking highly toxic 1976 

### Freshwater Fish, Chronic A freshwater fish early life-stage test using the TGAI is required according to Section 158.490(5):(i) niclosamid is directly applied to water and (ii) the LC,, is less than 1 ppm (0.19ppb in Daphnia magna and 0.34ppb in trout. None of the studies submitted to support the reregistration ofNiclosamidprovided useful data to address the 72-4a guideline requirementand as such represents a data gap. 

### Fresh water Invertebrates, Acute 

### A freshwater aquatic invertebrate toxicity test using the TGAI is required to establish the toxicity of niclosamide to aquatic invertebrates. Thepreferred test species is Daphnia magna. The toxicity of niclosamide to freshwater aquatic invertebrates spanned roughly three orders of magnitude (0.03 ppm 

### - > 50 ppm); since someLC,,/EC,, fall in the range of 

### <0.1 ppm, niclosamide is categorized as very highly toxic to aquatic invertebrates on an acute basis. The guideline (72-2) is fulfilled 

### (MRID 441748-04 ). Additional data were provided through a study of the effects of niclosamide (5% granular formulation) on benthic macroinvertebratesin a lake environment. Total numbers of organisms in the treated area dropped 56% within 7 days posttreatment and primarily affected oligochaetes and midge larvae; however, by 13 days posttreatment, the numbers of these organisms had increased(Gilderhus 

### 1979). Other species, 

### e.g., mayfly nymphs and amphipods, were not substantially affectedby theniclosamide treatment. The study concluded that the niclosamide is expectedtohave only moderate effects of short duration on populations of rnacroinvertebrates.Table 

### 9. Freshwater invertebrate acute toxicity of niclosamide. SpeciesIStatic or Flow- 96-hour LC,,/ % ai Toxicity Category MRID No. Study through ECs, (PP~) Authornear Classification (measured/nominal) Waterflea (Daphnia magna) 0.32 pprn 441748-04 70% highly toxic Drottar and Swigert (mean-measured) Core 1996 Waterflea 0.2 pprn (nominal) 436793-05 highly toxic H. 0.Sanders Supplemental 1977 Scud (Gammaruspseudolimnaeus) 70% 2.4pprn 436793-05 moderately toxic H. 0.Sanders Supplemental (nominal) 1977 Scud 2.6pprn 436793-06 moderately toxic Rye and King Supplemental (nominal) 1976 Snails (Physa sp.) 0.106 pprn (nominal) 436793-06 highly toxic Rye and King Supplemental 1976 Snails (Pleurocera sp.) 0.36pprn (nominal) 436793-06 highly toxic Rye and King Supplemental 1976 Glass shrimp (Palaemonetes kadiakensis) 70% 436793-05 10 PP~ moderately toxic H. 0.Sanders Supplemental (nominal) 1977 Clam (Eliptio dilatatus) 0.382 pprn (nominal) 436793-06 highly toxic Rye and King Supplemental 1976 Crayfish (Orconectes nais) 25 PPm (nominal) 436793-05 slightly toxic H. 0.Sanders Supplemental 1977 Crayfish >50 pprn (nomial) 436793-06 slightly toxic Rye and King Supplemental 1976 Midge 436793-05 (Chironomus plumosus) 70% 1 5 PP~ moderately toxic H. 0.Sanders Supplemental (nominal) 1977 Waterflea 0.8pprn (nominal) 436793-06 highly toxic Rye and King Supplemental 1976 Leeches (Erpobdellidae) 0.42 pprn (nominal) 436793-06 highly toxic Rye and King Supplemental 1976 Aquatic earthworms 436793-06 very highly toxic Rye and King Supplemental 1976 Turbellarian 436793-06 (Dugesia tigrina) 70% 0.048 very highly toxic Rye and King Supplemental 1976 '48-hour toxicity endpointToxicity of TFM and a mixture of Bayer 

### 73 to Aquatic Invertebrates Under certain conditions and situations, TFM is used with Bayer 73, another lampricide, to control of the sea lamprey. As such, it has been determined that data on the interaction ofthese two pesticides are required to establish the toxicity of TFM to freshwater aquatic invertebrate species. Results of these studies are tabulated below: Table 9. Toxicity of TFM:Bayer 73 (98:2 based on active ingredient) to aquatic invertebrates.

Species 98:2 Bayer 73 MRIDIautho mixture 24-h Toxicity category

LC50 LC50 rlyear mgll Turbellarium 1.5 0.048 Rye and moderately toxic King, 1976 Aquatic earthworms 2.25 0.034 moderately toxic Leeches 4 0.42 moderately toxic Daphnid 7.35 0.8 moderately toxic Isopod 31 23.0 slightly toxic Scuds 26 2.6 slightly toxic Crayfish > 100 >50 practically non-toxic Stoneflies 15.4 1.07 slightly toxic Dragonflies > 100 >50 practically nontoxic Burrowing mayflies Blackflies Snipeflies Dobsonflies Clam Pleurocera sp.

Physa sp. 4 6.9 moderately toxic 3.45 0.255 moderately toxic
> 100 >50 practically non-toxic
> 100 >50 practically non-toxic 4.7 0.382 moderately toxic 9.4 0.355 moderately toxic 1.93 0.106 moderately toxic These data indicate that LC50 values for a mixture 

### (98:2 by weight) of TFM and Bayer 73 range from 1.5 (moderately toxic) to more than 100.0 mglliter (practically non-toxic). The most tolerant species tested were crayfish, dragonflies, snipeflies, and dobsonflies. The most sensitive species were turbellarians, snails and aquatic earthworms. These data suggest that the mixture of TFM and Bayer 73 is less toxic to aquatic invertebrates than Bayer 73 alone. 

### Fresh waterInvertebrate, Chronic A freshwater aquatic invertebrate life-cycle test using the TGAI is required for Niclosamde sincethe end-use product is applied directly to water, the aquatic acuteLC5,/EC5,is less than 1mg/L and the EEC in water is equal to or greater than 0.01 of the acute LC5,/EC5,. The preferred test species is 

### Daphnia magna. Results of this test are tabulated below. Similar to acute toxicityestimates, chronic toxicity studies indicated that waterfleas were an order of magnitude more sensitive to the effects of niclosamide than were midges.

Table 10. Freshwater aauatic invertebrate life-cvcle toxicitv using niclosamide. Species/Static 21-day Renewal or Flow- % ai NOEC/LOEC MATC' Endpoints MRID No. Study through mg/L (PP~) Affected AuthorIYear Classification
Waterflea 0.056 mg/L reproduction 441872-01 (Dapknia magna) 100% 0.108 mg/L 0.078ppm length Drottar and Swigert Core 1996 Waterflea 436793-05 0'032 mgiL 0.042 pprn reproduction 70% 0.055mgiL H.O. Sanders Supplemental 1997 Midge 436793-05 (Ckironomusplumosus) 70% 0'32 mg/L 0.42 ppm emergence H.O. Sanders Supplemental 0.55 mg/L 1997
I defined as the geometricmean of the NOEC and LOEC.
Toxicity to Estuarine and Marine Animals 

### Estuarine andMarine Organisms,Acute and Chronic Neither acute nor chronic toxicity testing with estuarinelmarine organisms using the 

### TGAI is required for niclosamide because the end-use product is not intended for direct application to the marinelestuarine environment nor is the active ingredient is expected to reach this environment because it is not used in coastal counties. Toxicity to Plants 

### Aquatic Plants Normally, aquatic plant testing is not required for pesticides other than herbicides and fungicides except on a case-by-case basis (e.g., labeling bears phytotoxicity warnings incident data or literaturethat demonstratephytotoxicity). However, given that niclosamide is applied directlyto the water and given its toxicity to aquatic organisms, aquatic plant testing isrequired. The following species should be tested at Tier 

### I: Kirchneria subcapitata and Lemna gibba. Results of Tier 

### I toxicity testing onthetechnical1TEPmaterial using diatoms and green algae (Table 1 1) indicate that EC50 values ranged over four orders of magnitude (range 0.04 

### - 1,450). The species tested did not conform to the recommended species and the test conditions were poorly defined, thus, guideline 122-2is not fulfilled.Table 11. Nontarget aquatic plant toxicity testing using niclosamide. Species % ai EC50 MRID No. (PP~) AuthoriYear Study Classification Diatoms Ankistrodesrnus falcatus Scenedesrnus quadricauda 0.103 70 Ibrahim 1984 Supplemental 0.130 436793-10

Skeletonema costaturn Amphiprorapaludosa Ibrahim 1984 436793-10 Supplemental Phaeodactylum tricornutum 0.041

### APPENDIX 2. 

### EXPOSURE AND RISK CHARACTERIZATION Risk characterization integrates the results ofthe exposure and ecotoxicity data to evaluate the likelihood of adverse ecological effects. The means of this integration is called the quotient method. Risk quotients (RQs) are calculated by dividing exposure estimates by acute and chronic ecotoxicity values.

RQs are then compared to OPP's levels of concern (LOCs). These LOCs are used by OPP to analyze potential risk to nontarget organisms and the need to consider regulatory action. The criteria indicate that a pesticide used as directed has the potential to cause adverse effects on nontarget organisms. LOCs currently address the following risk presumption categories: (1) 

### acute high 

### -- potential for acute risk is high; regulatory action may be warranted in addition to restricted use classification, 

### (2) acute restricted use 

### --thepotential for acute risk ishigh, but maybe mitigated through restricted use classification, (3) 

### acute endangered species 

### - endangered species may be adversely affected, and (4) 

### chronic risk

### - the potential for chronic risk is high regulatory actionmay be warranted. Currently, EKED does not perform assessments for chronic risk to plants, acute or chronic risks to nontarget insects, or chronic risk from granularlbait formulations to birds or mammals. The ecotoxicity test values (, measurement endpoints) used in the acute and chronic risk quotients are derived from required studies. Examples of ecotoxicity values derived from short-term laboratory studies that assess acute effects are: (1) LC,, (fish and birds), (2) LD,, (birds and mammals), (3) EC,, (aquatic plants and aquatic invertebrates) and (4) EC25 (terrestrial plants). Examples of toxicity test effect levels derived fi-omthe results of long-term laboratory studies that assess chronic effects are: 

### (1) LOEC (birds, fish, and aquatic invertebrates), (2) NOEC (birds, fish and aquatic invertebrates), and 

### (3) MATC (fish and aquatic invertebrates). For birds and mammals, the NOEC generally is used asthe ecotoxicity test value in assessing chronic effects, although other values may be used when justified. Generally, the MATC (defined as the geometric mean of the NOEC and LOEC) is used as the ecotoxicity test value in assessing chronic effects to fish and aquatic invertebrates. However, the NOEC is used if the measurement end point is production of offspring or survival. Risk presumptions and the corresponding RQs and LOCs, are tabulated below.

### Table 1 

### Risk Presumptions for Terrestrial Animals Risk Presumption 

### RQ LOC Birds Acute High Risk EEC1ILCjO or LD,,/sqft2 or LDjo/day3 0.5 Acute Restricted Use EECILC,, or LDjdsqft or LD,,/day (or LD,, < 50 mglkg) 0.2 Acute Endangered Species EECLC,, or LD,,/sqft or LD,,/day 0.1 Chronic Risk EEC/NOEC 1 Wild Mammals Acute High Risk EECILC,, or LD,,/sqft or LD,,/day 0.5 Acute Restricted Use EECILC,, or LD,,/sqft or LD,,lday (or LD,, < 50 mglkg) 0.2 Acute Endangered Species EECILC,, or LD,,/sqft or LDjO/day 0.1 Chronic Risk EEC.1'OEC I 

### ' abbrwiation for Estimated Environmcntal Concmtration (ppm) on a\.ianimammalianfood itcms mg/ft2 

### ' mg of toxicant consumedlday LDjo

### * wt. of bird LD,, 

### * wt. of bird 

### Table 2 

### Risk presumptions for aquatic animals Risk Presumption RQ LOC Acute High Risk Acute Restricted Use Acute Endangered Species EEC1/LCSo or EC,, EEC/LC,, or EC,, EECILC,, or EC,, Chronic Risk EECIMATC or NOEC 1

EEC = (ppm or ppb) in water 

### Table 

### 3 Risk presumptions for plants Risk Presumption RQ LOC Terrestrial and Semi-Aquatic Plants Acute High Risk Acute Endangered Species

Acute High Risk EEC1/EC25 EECIECO5 or NOEC Aquatic Plants EEC2IEC5, Acute Endangered Species EECIECOS or NOEC 1 EEC = Ibs ai/A EEC = (ppblppm) in waterExposure and Risk to Nontarget Terrestrial Animals 

### Acute Risk Quotients for Avian and Mammalian Species Acute Risk Quotients for Avian and Mammalian Species Niclosamide is only registered for use on aquatic sites. Therefore, the typical terrestrial analysis of risk, based on exposures developed by Hoerger and Kenega (1972) and as modified by Fletcher et al., (1994), is not applicable for establishing the risk of niclosamide to on-target terrestrial species. However, because numerous avian, i.e., waterfowl and shorebirds, and mammalian species (muskrats, beavers, raccoons and numerous other small mammals) typically utilize aquatic environments as nesting and/or feeding habitats and may be exposed to niclosamide via contaminated water, it is appropriate to use the aquaticEECs for conducting therisk assessment toterrestrial species. Tables 

### 4 and 5 showthe

### RQvalues for birds and mammals, respectively, based on a target stream concentration of 

### 9 ppm. Table 4. Acute risk quotients for avian species. Species LC,, EEC (pprnl* Risk Quotient PP'" Bobwhite quail (Colinusvirginianus) Mallard duck >5,648 0.050 0 (Anas platyrhynchos) * The typical concentration expected to occur in streams treated with Niclosamidewas used to predict exposure and calculated the RQ. Table 5. Acute risk quotients for mammalian species. Species Body % body EEC LC,, Risk Quotient* weight wt. (PP~)* PPm Consumed small mammal 15 10 0.050 > 1,000 0

1000 10 0.050 0 * RQ= EEC (ppm) LDso(mg/kg)/O/~ Body wt. Consumed The analysis of the data shows that no terrestrial species LOC are exceeded from the proposed use ofniclosamide. In addition, there are no reported incidents involving niclosamide and any terrestrial species. Exposure and Risk to Nontarget Freshwater Aquatic Animals 

### Fresh water Fish RQ values calculated for the minimum EEC of 25 ppb (Table 6), range from 0.15 to 0.83. Acute restricted use LOCs were exceeded in 40% of the fish represented. At a treatment concentration of 35ppb, 

### RQ values ranged from 0.29to 1.3 1;acute high risk LOCs were exceeded in 

### 50% of the fish represented.Table 6. Summary of risk quotients to fresh water fish species based on predicted treatment levels of niclosamide at 25 and 35 ppb. Species/ EEC 96-hour Flow-throughor Static (PP~) LC,, (PP~) EEC (PP~) Rainbow trout Bluegill sunfish

Sea lamprey 0.025 0.049 0.5' 0.035 0.71" Carp (Qprinuscalpio)

Green sunfish (Lepomiscyanellus) 0.025 0.170 0.15** 0.035 0.50'
* Acute hlgh risk, acute restricted use and endangered species LOCs exceeded. **Acute restricted use and endangered species LOCs exceeded. ***

Endangered species LOCs exceeded 

### Acute risk quotients for a mixture ofTFM and niclosamidewere calculated (Table 

### 7). The RQ for the minimum predicted treatment concentration range from 0.60 to 1.13 while the RQ for the maximum predicted treatment concentration range from 1.9 to 3.57. An analysis of the results indicate that aquatic acute high risk, restricted use, and endangered species levels of concern are exceeded for freshwater fish at typical use rates of TFM and niclosamide which result in environmental concentrations of 0.7 to 2.2 ppm. A comparisonbetween the RQ for TFM and the mixture of TFM and niclosamide indicate that the mixture results in an additive affect that poses more risk to fish from the mixture than 

### TFM alone.
Table 7. Acute risk quotients for a mixture (98:2 by weight) of TFM and niclosamide for fish. 

### Species LC,, (PP~) EEC(PP~) 

### RQ EEC (PP~) 

### RQ

Channel catfish 0.615 Brown Trout 0.98 0.7 0.71' 2.2 2.2" Yellow perch 0.9 0.7 0.78" 2.2 2.4' Rainbow trout 1.16 0.7 0.60' 2.2 1.90' Acute high risk, acute restricted use and endangered species LOCs exceeded.


### The rainbow trout RQ, based on the 96-hour 

### LC,, values derived at various pH, range from 0.135 to 0.958 for the minimum EEC of 25 ppb, while the RQ for the maximum EEC of 35 ppb range from 0.189 to 1.40 (Table 8). 

### At both the minimum and maximum EEC, the acute high risk 

### LOC will be exceeded 

### for rainbow trout in streams with pH up to 7.5.

### Table 

### 8. Summary of risk quotientsto the rainbow trout, 

### Oncorhynchusmykiss,based on pH 

### (Bills and Marking, 1976). PH 96-hr LC,, EEC RQ EEC RQ 6 5 0 0261 0 025 0 958' 0.035 1.40'

9.5 0.185 0.025 0.135'" 0.035 0.189** "Acute high risk, acute restricted use and endangered speciesLOCs exceeded. "Acute restricteduse and endangered species LOCs exceeded. 

### Aquatic Invertebrates The 

### RQ for aquatic invertebrates at the minimum

### EEC of 

### 25 ppb range from 0.001 to 0.74, while the RQ for the maximum EEC of35

### ppm range from 0.001

### to 1.02

### (Table 9). 

### Acute highrisk LOCs are exceeded for aquatic earthwormsand flatworms (Turbellaria). Endangered speciesLOCs are exceeded for 64%ofthe species tested at both estimated treatment levels of 

### 25 and 35 

### ppm 

### Table 9. 

### Acute risk quotients of niclosamide for aquatic invertebrates. 96-hour Species EEC EC50 (PP~) RQ EEC (PP~) RQ

Waterflea 0.2pprn 0.025 0.125" 0.035 0.175''
Scud (Gammaruspseudolimnaeus) Snails (Physa sp.) Snails (Pleurocera sp.) Glass shrimp (Palaemonetes kadiakensis) Clam (Eliptio dilatatus) Crayfish (Orconectes nais) Midge (Chironomusplumosus) Leeches (Erpobdellidae) Aquatic earthworms (Tubifex tubifex) 2.4 ppm

0.106 ppm

0.36 ppm

10 PPm

0.382 ppm

25 PPm

1.5ppm

0.42 ppm

0.034
Turbellarian (Dugesia tigrina) 0.048 0.025 0.52' 0.035 0.73' ' Acute high risk, acute restricted use and endangered species LOCs exceeded. *' Acute restricted use and endangered species LOCs exceeded ""Endangered species LOCs exceededThe RQ for aquatic invertebrates, for the mixture of TFM and niclosamide, at the minimum predicted concentration of 0.7 ppm, range from 0.03 to 0.46, while the RQs for the maximum predicted treatment concentration of 

### 2.2 ppm range from 0.08 to 

### 1.47 (Table 

### 10). Acute restricted use and endangered species LOC are exceeded for aquatic invertebrates at minimum predicted treatment concentrations for waters ofpH 7.2 

### - 7.6. A comparison between the RQs for TFM and the mixture of TFM and Niclosamide indicate that the mixture results in an additive affect that is more toxic to aquatic invertebrates than TFM alone. The data suggest that Tubellariums (aquatic worms) are at the greatest risk from the use of mixture of TFM and niclosamideto control the sea lamprey. Data also suggest however, that while the TFMIniclosamide mixture results in higher toxicity to aquatic invertebrates, the increase in toxicity is not proportional to that of the lamprey. In other words, lampreys undergo a marked increase in toxicity to the TFMIniclosamidecompared to the relatively small increase in sensitivity exhibited by aquatic invertebrates. This differential toxicity between sea lamprey larvae and nontarget aquatic invertebrates as a result of using the TFMIniclosamidemix is exploited to enhance mortality of ammocoetes while reducing effects on nontargets (pers. comm. Terry Bills, Fishery Biologist, U.S. Geological Survey 1999). Table 10. Acute riskquotients ofa mixture (98:2 by weight) ofTFM and niclosamide for aquatic invertebrates. Species LC5, (PP~) EEC RQ EEC (PP~) RQ Tubellarium 1.5 0.7 0.46'* 2.2 1.47' Amphipoda (G.psuedolinneaus) Diptera (Simulium sp.)

Gastropoda 1.93 0.7 0.36*' 2.2 1.13' (Physa SP) 'Acute high risk, acute restricted use and endangered species LOCs exceeded. *, Acute restricted use and endangered species LOCs exceeded. Exposure and Risk to Nontarget Aquatic Plants The RQ for aquatic plants, at the minimum EEC of 25 ppb, range from less than 0.01 to 0.61, while the RQ forthe maximum EEC of 35ppb range from liessthan 0.01 to 0.85 (Table 11). No acute levels of concern were exceeded.Table 11. Risk Quotients (RQ) for nontarget aquatic plants exposed to niclosamide. Species EC50 EEC RQ EEC (PP~) (PP~) (PP~) RQ
Diatoms Ankistrodesmus falcatus 0.103 0.025 0.243 0.035 0.34 Scenedesmus quadricauda 0.130 0.025 0.192 0.035 0.27 Phaeoda3lurn tricornuturn 

### - - 0,043 

### - --- 

### ---- 0.81 - 0.E- - - 

### 2.58 - -- -0.035- -- 

## - Green Algae Skeletonema costaturn 71 0.025 <0.01 0.035 ~0.01 Arnphiprorapaludosa 1,450 0.025 <0.01 0.035 <0.01 Phaeodactylurn tricornuturn 0.041 0.025 0.61 0.035 0.85