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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

 WASHINGTON, D.C. 20460

 OFFICE OF

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

September 24, 2009

MEMORANDUM

SUBJECT: Response to Comments on the Reregistration Eligibility Decision for 

Antimycin A

FROM: Lance Wormell, Chemical Review Manager

Dirk Helder, Chemical Review Manager

Risk Management Implementation Branch II

Pesticide Re-evaluation Division (7508P)

THROUGH: Margaret Rice, Chief 

Risk Management Implementation Branch II

Pesticide Re-evaluation Division (7508P)

TO: Public Docket EPA-HQ-OPP-2006-1002

This document presents the Environmental Protection Agency‟s (EPA or “the 

Agency”) formal response to the comments received on the 2007 Reregistration 

Eligibility Decision (RED) for Antimycin A. These comments were received during the 

60-day public comment period that ended on August 13, 2007. During the comment 

period, EPA received responses from various stakeholders including state fish 

management agencies, interest groups, members of the public, and the user community. 

Comments are presented in bold font and EPA‟s response is presented below each 

comment.

Comment: The rationale for requiring a 7-day interval before restocking fish 

following a “total kill” treatment is unclear and the restriction is unnecessary. The 

restriction should allow for restocking after levels are below the limit of detection.

EPA response: No quantitative risk assessment for dietary exposure to antimycin A was 

done, thus the Agency‟s goal is to completely eliminate potential dietary exposure. The 

Agency believes a 7-day prohibition on restocking fish following a total kill treatment

will ensure there are no concentrations of antimycin A in the treated water and no 

residues in fish harvested from those treated ponds. Depending on environmental 

conditions, the expected half-life of antimycin A ranges from several minutes to 

approximately 12 hours. Based on the conservative estimate that antimycin A will have a 
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half-life of 12 hours, the Agency estimates that greater than 99% of the compound will 

have degraded after 7 days and concentrations will be below the limit of detection and 

fish can then be re-stocked. The Agency is allowing the option of either waiting a 

minimum of 7 days after treatment before restocking fish or restocking fish after 3 

consecutive monitoring samples taken no less than 4 hours apart demonstrate that 

antimycin A levels are below the limit of detection (0.015 ppb).

Comment: Consumption of fish should be prohibited for 12 months following a 

“partial kill” treatment to prevent dietary exposure to antimycin A residues in those 

treated fish rather than specifying an exact cutoff in antimycin A water 

concentration.

EPA response: When data are not available to estimate residues of pesticides in food or 

feed, as is the case with antimycin A, the Agency typically requires a 12-month preharvest interval. EPA considers 12 months to be sufficient time to allow residues to 

dissipate below levels that may pose a risk to human health unless data are available to 

indicate the contrary. Antimycin A does not bioconcentrate in fish nor does it 

bioaccumulate in aquatic food chains. Antimycin A is applied only once, therefore, longterm or repeat exposure to antimycin A is not expected to occur. Based on the chemical‟s 

low likelihood to bioconcentrate and the fact that fish would only be exposed one time 

and for a short duration, the Agency agrees that a 12-month harvesting restriction is 

necessary and will preclude dietary exposure to antimycin A residues in fish following 

partial kill treatments.

Comment: Antimycin A is applied at a rate of 5-10 parts per billion (ppb) to kill 

unwanted fish in channel catfish ponds (i.e., ponds that are supplied with natural 

water sources and, consequently, contain unwanted fish species). The proposed 12-

month prohibition on consuming treated fish would either eliminate this use or, 

when fish from these ponds are used for stocking other water bodies, result in the 

spreading unwanted fish species in public fishing lakes.

EPA response: The Agency believes antimycin A can safely be used in water bodies to 

control unwanted fish but the use of antimycin A in public lakes or applications to fish 

stocked in public lakes prior to the 12-month pre-harvest interval is not allowed. No

quantitative risk assessment for dietary exposure to antimycin A was done, thus the 

Agency‟s goal is to eliminate potential dietary exposure. EPA considers 12 months to be 

sufficient time to allow residues to dissipate below levels that may pose a risk to human 

health unless data are available to indicate the contrary. Based on the chemical‟s low 

likelihood to bioconcentrate and the fact that fish would only be exposed one time and for 

a short duration, the Agency believes the 12-month harvesting restriction is necessary to 

preclude dietary exposure to antimycin A residues in surviving fish from use in 

aquaculture. 

Comment: Recreational access should be allowed in flowing waters after the 

chemical has moved beyond the access point and prohibiting recreational activities 

for 7 days after treatment is not necessary in flowing water and contact with 
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standing water should only be prohibited when concentrations exceed the detection 

level of 0.015 ppb.

EPA response: Since no toxicity or exposure data are available to conduct a quantitative 

risk assessment for recreational exposure to antimycin A, the Agency‟s goal is to 

eliminate any potential recreational exposure. Most flowing water also have stagnant 

areas that receive little to no stream circulation where antimycin A concentrations could 

remain high (e.g., those pockets or eddies treated with handheld sprayers). Depending on 

environmental conditions and based on the conservative estimate that antimycin A will 

have a half-life of 12 hours, the Agency estimates that it will take 7 days for at least 99% 

of the compound to degrade and concentrations will be below the limit of detection. 

Therefore, the Agency believes a 7-day prohibition on recreational access following an 

antimycin A is necessary in the absence of data to confirm that a shorter restriction would 

be protective.

Comment: Requiring PPE when reentering treated areas is not necessary when 

antimycin concentrations in the water are less than current detection level of 

0.015 ppb. 

EPA response: The Agency agrees that concentrations below the limit of detection 

(0.015 ppb) would not likely present a risk of concern to handlers re-entering the treated 

area; however, the current analytical method requires laboratory analysis, the results of 

which would not likely be available for several days. Therefore, in most cases water 

sampling would not be useful to determine concentrations in the water body following an 

application and prior to reentry into a treated water body by handlers. Depending on 

environmental conditions and based on the conservative estimate that antimycin A will 

have a half-life of 12 hours, the Agency estimates that it will take 7 days for at least 99% 

of the compound to degrade below the limit of detection. Therefore, the Agency will 

require PPE (waders, chemical-resistant gloves and protective eyewear) for handlers

reentering a treated water body within 7 days following an antimycin A application. The 

PPE is similar to what most anglers wear when entering a stream environment and the 

Agency does not believe it is overly burdensome. 

Comment: Requiring PPE when reentering a treated stream is unnecessary 

provided antimycin A has had sufficient time to pass through the treatment area.

EPA response: Most treatment areas, including flowing water bodies, have stagnant 

areas that receive little to no stream circulation (e.g., those pockets or eddies treated with 

handheld sprayers). Depending on environmental conditions, the expected half-life of 

antimycin A ranges from several minutes to approximately 12 hours. Based on the 

conservative estimate that antimycin A will have a half-life of 12 hours, the Agency 

estimates that residues in water could exist for 7 days following an application and 

handlers reentering a treated stream could be exposed to antimycin A concentrations. 

Thus, the Agency is requiring PPE for handlers reentering a treated stream including 

waders, chemical-resistant gloves and protective eyewear. The PPE is similar to what 
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most anglers wear when entering a stream environment and the Agency does not believe 

it is overly burdensome.

Comment: Respirator requirements should be removed because they are not 

warranted based on risk and will be overly burdensome for applicators.

EPA response: Using the existing database, EPA cannot conduct a quantitative risk 

assessment and, therefore, cannot conclude that inhalation exposure to handlers without a 

respirator result in risk below the Agency‟s level of concern (LOC). The Agency is 

requiring respiratory protection for those handlers most likely to have respiratory 

exposure including mixers, loaders and handlers exposed to liquid concentrate and 

applicators using handheld equipment. EPA does not believe dust mist respirators are 

overly burdensome for these handlers but will consider removing or reducing this 

restriction upon submission of exposure and toxicity data that demonstrate handler risk 

below the LOC.

Comment: Deactivation with potassium permanganate should not be required 

because potassium permanganate use may not always be necessary or desirable 

depending on the results of the pre-treatment environmental analysis.

EPA response: The persistence of antimycin A can vary depending on environmental 

conditions. Because of uncertainties associated with the potential effects on humans and 

because of the known effects of antimycin A on nontarget animals such as aquatic 

invertebrates, the Agency is attempting to limit nontarget exposure by requiring 

antimycin A deactivation with potassium permanganate when the piscicide is applied to 

flowing water. Depending on flow rates, environmental conditions and treatment rates, 

antimycin A can potentially move beyond targeted treatment areas and expand the 

affected area. The extent to which this would occur could be highly variable and 

uncertain. Exposure of nontarget organisms outside the treatment area is intended to be 

limited through rigorous application standard operating procedures used by trained 

fishery professionals and deactivating antimycin A with potassium permanganate. The 

Agency agrees there are some situations where deactivation is not possible or 

unnecessary, e.g. in a steep canyons and those situations will be outlined in the antimycin 

A SOP manual.

Comment: Geographically specific restrictions on the use of antimycin A should not 

be implemented so that any take of listed species may be authorized by the 

appropriate authority.

EPA response: The RED has not required any geographically specific restrictions. 

Applicators using antimycin A in listed species habitat must consult with the US Fish and 

Wildlife Service. The requirements for conducting formal or informal consultation, 

depending on the nature of the action and the potential species and/or habitat affected, 

will be presented in the antimycin A SOP manual.
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Comment: The prohibition of use in estuarine/marine environments should be 

removed because uses and risks are similar for these environments.

EPA response: It is EPA‟s understanding that antimycin A is not used in 

estuarine/marine environments and no data have been submitted on its fate and/or toxicity 

to estuarine/marine environments/organisms. EPA will consider removing this restriction 

upon submission of updated labels with instructions for use in estuarine/marine 

environments as well as data characterizing the fate and toxicity of antimycin A in the 

marine/estuarine environment.

Comment: All enforceable label language should appear on the product label and 

the antimycin A Standard Operating Procedures (SOP) manual should contain only 

advisory/informational statements. Because piscicidal applications are so complex 

and because circumstances vary significantly, it is impossible to craft mandatory 

detailed instructions that will apply in every situation.

EPA response: The Agency believes antimycin A applications are often quite complex 

requiring many factors be considered by the certified applicators. The Agency agrees 

that labels should include enforceable language and may need to incorporate by reference 

more detailed, instructions in the antimycin A SOP manual.

Comment: Collection and disposal of dead fish should not be required.

EPA response: The labeling requirements state that, users should collect and bury dead 

fish where practical. It is not a requirement.

Comment: Rinsate from cleaning activities should be disposed of in the treatment 

area.

EPA response: The Agency agrees rinsate from cleaning activities should be disposed of 

in the treatment area. The label table will be revised to make this clarification.

Comment: There is no guidance to differentiate between partial and complete kills 

(except in the concentrations and durations used and the sensitivities of the target 

species) and label language required by the RED that refers to partial kills should 

be removed.

EPA response: It is EPA‟s understanding that antimycin A is currently used for both 

complete kills and selective kills, although selective kill applications are used only in 

aquaculture. Therefore, detailed directions for use are required for both uses. In lieu of 

these instructions, the registrant may amend the product label to allow only complete kills 

and prohibit any other uses. Detailed guidance for conducting bioassays and designing 

treatment will be presented in the antimycin A SOP manual.

Comment: The Certified Applicator should only be required to be in contact with 

the treatment operation and not onsite.
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EPA response: Because piscicidal applications are so complex and because 

circumstances vary significantly, the Certified Applicator must remain onsite during 

treatment.

Comment: Placarding instructions in the RED are excessive, especially for large 

treatment areas.

EPA response: The label table will be revised to account for reduced placarding 

requirements for large or inaccessible treatment areas.

Comment: Handheld equipment should not be limited to backpack sprayers. 

Antimycin A is sometimes applied with electric or gasoline powered sprayers 

mounted on vehicles.

EPA response: The label table will be revised to include instructions for “handheld 

equipment, handheld nozzles or other equipment.”

Comment: Chest waders may not be appropriate in all instances (depending on 

water depth, etc.) and should be changed to “waders.”

EPA response: The label table will be revised to specify “waders” instead of “chest 

waders.”

Comment: The benefits and alternatives comparison of rotenone and antimycin A 

appears to be inaccurate. Both piscicides are used at low concentrations to remove 

nonnative fish from high alpine water bodies, rotenone could replace antimycin A in 

all situations, and the chemical cost is substantially higher for antimycin A.

EPA response: EPA agrees that both rotenone and antimycin A can and are used to 

remove nonnative fish from high alpine water bodies as well as to selectively remove fish 

from standing water bodies. The Agency‟s assessment did not imply that rotenone is not 

used for this purpose, only that, rotenone is most often used to treat standing water, such 

as large ponds, lakes, and reservoirs. However, and while acknowledging that the cost for 

rotenone varies widely depending on application rates, the Agency believes that, in 

general, the cost of treating water bodies with rotenone and antimycin A appears to be 

comparable (Kaul et al., 2006). The Agency would be interested in additional cost 

comparison by the respondents or any other cost analysis comparing rotenone and 

antimycin A, under similar conditions, and using application rates intended to achieve 

comparable results.
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Tables 1 and 2 update and supersede Tables 6 and 7, respectively, in the May 2007 RED (EPA 738-R-07-007).

Table 1. Revised Label Changes Summary Table for Antimycin A Manufacturing-Use Products1

Description Amended Labeling Language for Manufacturing Use Products Placement on Label

For all Manufacturing 

Use Products

“Only for formulation into a piscicide (fish kill) for the following use(s) 

[MUP registrant, insert those uses that are being supported by the 

RED].”

“Only for formulation into products that are classified as Restricted Use.”

Directions for Use

Additional Uses “This product may be used to formulate products for any additional 

use(s) not listed on the MUP label if the formulator, user group, or 

grower has complied with U.S. EPA submission requirements regarding 

support of such use(s).”

Directions for Use

Environmental Hazards 

Statements Required 

by the RED and 

Agency Label Policies 

“This product is extremely toxic to fish and other aquatic organisms.”

“Do not contaminate water, food, or feed by storage or disposal.”

“Do not discharge effluent containing this product to sewer systems 

without notifying the local sewage treatment plant authority."

Precautionary Statements

1 Note: Currently there is no registered manufacturing use product for antimycin A. 
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Table 2. Label Changes Summary Table for Antimycin A End-Use Products Intended for Occupational and Residential Use

Description Amended Labeling Language for End-Use Products Placement on Label

RUP “Restricted Use Pesticide.”

“Due to toxicity to fish and other aquatic organisms and the need for 

specialized applicator training.”

“For retail sale to and use by only Certified Applicators or persons under 

their direct supervision and only for those uses covered by the Certified 

Applicator‟s certification.”

This statement must appear at the very 

top of the label's front panel [see 40 CFR 

156.10(j)(2)(i) for more information]. 

No other wording or symbols may 

appear above the RUP statement.

SOP Manual “THE APPLICATOR IS RESPONSIBLE FOR CONFORMING TO 

THE LABEL. IMPORTANT GUIDANCE ON THE SAFE AND 

EFFECTIVE USE OF THIS PRODUCT AND CONFORMING TO THE 

LABEL IS PROVIDED IN THE ANTIMYCIN A STANDARD 

OPERATING PROCEDURES (SOP) MANUAL, AVAILABLE FROM 

THE REGISTRANT.”

Immediately below the RUP statement 

on the label and on the cover page of the 

antimycin A SOP Manual.
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Description Amended Labeling Language for End-Use Products Placement on Label

PPE Requirements 

Established by the 

RED1

for all Formulations

“Personal Protective Equipment (PPE)

Some materials that are chemical-resistant to this product are” [EUP

registrant, insert correct chemical-resistant material]. “If you want 

more options, follow the instructions for category” [EUP registrant, 

insert A, B, C, D, E, F, G, or H] “on an EPA chemical-resistance 

category selection chart.

All mixers, loaders and other handlers exposed to the concentrate through 

cleaning equipment or spills must wear:

* long-sleeved shirt and long pants,

* chemical-resistant gloves,

* shoes plus socks, 

* protective eyewear, and

* a dust mist filtering respirator (MSHA/NIOSH approval number prefix TC21C), or a NIOSH approved respirator with any N, R, P, or HE filter, and

* a chemical-resistant apron.

All applicators and other handlers must wear:

* long-sleeved shirt and long pants,

* chemical-resistant gloves,

* shoes plus socks, and

* protective eyewear.

In addition, applicators using handheld equipment, handheld nozzles or 

other equipment must wear:

* coveralls, and 

* a dust/mist filtering respirator (MSHA/NIOSH approval number prefix 

TC-21C), or a NIOSH approved respirator with any N, R, P, or HE filter.

Exception: Applicators exposed to splashing water or walking in water 

that is being treated must wear waders instead of coveralls. All other 

applicators and handlers may substitute waders for long pants if 

necessary.”

Precautionary Statements under the 

heading “Hazards to Humans and 

Domestic Animals”
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Description Amended Labeling Language for End-Use Products Placement on Label

User Safety 

Requirements

“Do not wear contact lenses while handling this product. Ocular contact 

with this product can melt a contact lens onto the eye.” 

“Follow manufacturer's instructions for cleaning/maintaining PPE. If no 

such instructions for washables exist, use detergent and hot water. Keep 

and wash PPE separately from other laundry.”

“Discard clothing and other absorbent materials that have been drenched 

or heavily contaminated with concentrated product. Do not reuse them.”

Precautionary Statements under the 

heading “Hazards to Humans and 

Domestic Animals” immediately 

following/below the PPE requirements

User Safety 

Recommendations

“User Safety Recommendations”

“Certified Applicators applying or supervising any aspect of the 

application of this product should attend a training program for piscicide 

applications.”

“Users should wash hands before eating, drinking, chewing gum, using 

tobacco, or using the toilet.”

“Users should remove clothing/PPE immediately if pesticide gets inside. 

Then wash thoroughly and put on clean clothing.”

“Users should remove PPE immediately after handling this product. 

Wash the outside of gloves before removing. As soon as possible, wash 

thoroughly and change into clean clothing.”

Precautionary Statements under the 

heading “Hazards to Humans and 

Domestic Animals” immediately 

following/below the Engineering 

Controls.

(These statements must be placed in a

separate box.)

Environmental Hazards “Environmental Hazards”

“This product is extremely toxic to fish and other aquatic organisms.”

“Do not contaminate water outside the treatment area by cleaning of 

equipment or disposal of equipment wash waters.”

“Do not contaminate water outside the treatment area, food, or feed by 

storage or disposal.”

“Do not discharge effluent containing this pesticide into sewage systems 

without notifying the sewage treatment plant authority (POTW).”

Precautionary Statements under the 

heading “Hazards to Humans and 

Domestic Animals” immediately 

following/below User Safety 

Recommendations
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Description Amended Labeling Language for End-Use Products Placement on Label

Personal Protective 

Equipment When Reentering Treated Areas

“Re-entering the Treatment Area”

“For the first 7 days after treatment, handlers re-entering treated water 

must wear at a minimum the following PPE:

* Waders and long-sleeved shirt,

* chemical-resistant gloves, and

* protective eyewear.”

Direction for Use under the heading 

“Re-Entering the Treatment Area”

Complete and Selective 

kills

“Complete and Selective Kills”

“This product may be used to achieve a „complete kill‟ or a „selective 

kill.‟ Complete kills are intended to eliminate all fish in the treatment 

area whereas selective kills, used only in aquaculture, are intended to 

eliminate or reduce the number of only certain (more vulnerable) species. 

Detailed instructions for conducting complete and selective kills are 

presented in the antimycin A SOP Manual.”

Directions for Use under the heading 

“Complete and Selective Kills”
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Description Amended Labeling Language for End-Use Products Placement on Label

General Application 

Restrictions for all 

Formulations

“The Certified Applicator supervising the treatment must remain on-site 

for the duration of the application.”

“Do not allow recreational access (e.g., wading, swimming, boating, 

fishing) within the treatment area while antimycin A is being applied and 

for 7 days after treatment.”

“For „complete kill‟ use, do not apply this product in a way that will 

result in treatment concentrations greater than 25 parts per billion. For 

„selective kill‟ use in aquaculture, do not apply this product in a way that 

will result in treatment concentrations greater than 10 parts per billion.”

“Do not apply this product in a way that will contact workers or other 

persons, either directly or through drift. Only protected handlers may be 

in the area during application.” 

“Do not apply with any application method or equipment or in a manner 

not specified on this label or in the antimycin A SOP Manual.”

"This product must not be applied to estuarine or marine environments."

“Where practical, users should collect and bury dead fish.”

Directions for Use

Additional 

Requirements for Use 

in Aquaculture

“Additional Requirements for Use in Aquaculture”

“When antimycin A is applied as a selective kill in aquaculture, the 

Certified Applicator supervising the application must inform the 

owner/operator of the aquaculture site being treated that surviving fish 

must not be harvested for food or feed for a minimum of 12 months after 

treatment.”

“When antimycin A is applied as a complete kill in aquaculture, the 

Certified Applicator supervising the application must inform the 

owner/operator of the aquaculture site being treated that the water body 

must not be restocked with fish for a minimum of 7 days after treatment, 

OR once 3 consecutive monitoring samples taken no less than 4 hours 

apart demonstrate that antimycin A levels are below the limit of detection 

(0.015 ppb).”

Directions for Use under the heading 

“Additional Requirements for Use in 

Aquaculture”
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Description Amended Labeling Language for End-Use Products Placement on Label

Drinking Water 

Notification 

Requirements

“Drinking Water Notification”

“If drinking water intakes are present within the treatment area, or a 

hydrologic connection to wells exist, 7-14 days prior to application, the 

Certified Applicator or designee under his/her direct supervision must 

provide notification to the party responsible for the public water supply 

or to individual private water users. Drinking water intakes within the 

treatment area must be closed during treatment and until 3 consecutive 

monitoring samples taken no less than 4 hours apart demonstrate that 

antimycin A levels are below the limit of detection (0.015 ppb).”

“Detailed instructions for public involvement, notifications, and 

monitoring are presented in the antimycin A SOP Manual.”

Directions for Use under the heading 

“Drinking Water Notification”
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Description Amended Labeling Language for End-Use Products Placement on Label

Notification 

Requirements for all 

applications except 

aquaculture 

applications

“Placarding of Treatment Areas, Except Aquaculture Applications” 

“The Certified Applicator in charge of the application (or someone 

under his/her supervision) must placard all access areas to the 

treatment area. Placards must be placed every 250 feet along the 

shoreline of the treated area, OR, at public access points (e.g., 

trailheads and roads and trails). Placards must contain the 

information below:”

* “DANGER/PELIGRO”

* “DO NOT ENTER WATER/NO ENTRE: Pesticide Application”

* The name of the product applied

* The agency or entity performing the application

* The purpose of the application

* The start date and time of application

* The end date and time of application

* The duration of the area closure

* “Recreational access (e.g., wading, swimming, boating, fishing, 

etc.) within the treatment area is prohibited while antimycin A is 

being applied and for 7 days after treatment.”

* “Do not swim or wade in treated water.”

* “Do not consume water or dead fish from treated water.”

* The name, address, and telephone number of the responsible agency 

or entity performing the application.

“Signs must remain legible during the entire posting period and must be 

removed no earlier than 7 days after treatment and no later than 14 days 

after treatment.”

Directions for Use under the heading 

“Placarding of Treatment Areas” 
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Description Amended Labeling Language for End-Use Products Placement on Label

Deactivation with 

Potassium 

Permanganate

“Deactivation with Potassium Permanganate”

“Flow in a stream and outflow from a treated lake beyond the treatment 

area must be deactivated with potassium permanganate to minimize 

exposure beyond the treatment area unless unnecessary. (See the 

antimycin A SOP Manual for the definition of treatment area, examples 

when treatment with potassium permanganate is unnecessary and detailed 

guidance for deactivating antimycin A with potassium permanganate.)”

Directions for Use under the heading 

“Deactivation with Potassium 

Permanganate (KMnO4)”

1

PPE that is established on the basis of Acute Toxicity of the end-use product must be compared to the active ingredient PPE in this document. The more 

protective PPE must be placed in the product labeling. For guidance on which PPE is considered more protective, see PR Notice 93-7.