STATES ENVIRONMENTAL PROTECTION
AGENCY

OFFICE OF CHEMICAL SAFETY
AND POLLUTION PREVENTION

PC Code : 031520, 119046

, and 129046
DP Barcode: 423438

. Date: December 10, 2014
MEMORANDUM

SUBJECT:

FROM:

REVIEWED
BY:

THROUGH:

TO: EFED Responses to Public Comments on the EFED Problem Fo rmulation for the Environmental Fate and Eco logical Risk, Endangered Species, and Drinking
Water Assessments (DP Barcode: 416759) in Support of the Registration Review
of Mecoprop-p (MCPP-p )

. Docket ID: EP A-HQ-OPP-20 14-0361

, Case 0377
and Addendum to Data Gaps Identified in the Problem Fo rmulation

Steve Carey, Biologist 

# 2h.A ('

_..... -"' 

# 17/t ill;'/

Ibrahim Abde l -Sa heb

, 

# Ph~TnvYron~l Scientist 1

Environmen t al Risk Branch VI
E nvironmental Fate and Effects Division (7507P)

Monica Wait, RAPL
Environmenta l Risk Branch VI Environmental Fate and Effects Division (7507P) 

# cJ Mark Corbin, Branch Chief Environmental Risk Branch VI

__ 

## 0

. Environmental Fate and Effects Division (:; )

Marianne Mannix, Chemica l Review Manager Patricia Parrott, Branch Chief
Risk Management and Implementation Branch Ill Pesticide Re-Evaluation Division (7508P)

This memorandum tran smi ts the EFED response to comments submitted by the MCPP-p Task Force, San Francisco Bay Regional Water Quality Control Board, and Ca li fornia Central Valley Regional Water Qua li ty Control Board. In addition, the memorandum is updating the data gaps for MCPP-p which were identified in t he Problem Formulation.

12 

# MCPP-p Task Force Comments

Problem Formulation for the Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments in Support of the Registration Review of Mecoprop- p (MCPP-p)
Docket ID: EPA- HQ -O PP -2014-0361-0002

GENERAL COMMENTS

1. Because amines and salts of MCPP-p quickly dissociate to the MCPP-p anion, as does the acid at physiologically, environmentally and agriculturally relevant pH conditions, all these forms can be considered essentially equivalent for the purposes of risk assessment. Quan titative application of results may require adjustment of values to reflect the respective molecular weights. For simplicity, all results are presented in terms of "acid equivalent" in quantitative risk assessments.

2. EPA Excerpt from the Problem Formulation : “For the honeybee adult 10 -day chronic oral study, MCPP-p is a systemic phenoxy which the plant absorbs the test material by the foliage or roots of the plant and is translocated throughout the whole plant to roots, leaves, etc.., increasing the likelihood that a pollinator would be exposed to MCPP-p EPA is requesting the special study to evaluate the chronic effects of MCPP-p to pollinators.”

Task Force Comment : Suggest minor edits for clarification: “For the honeybee adult 10

- d ay chronic oral study, EPA observes that MCPP-p is a systemic phenoxy which the plant absorbs by the foliage or roots and which is translocated throughout the whole plant to roots, leaves, etc.., increasing the likelihood that a pollinator would be exposed to MCPP-p. EPA is requesting the special study to evaluate the chronic effects of MCPP-p to pollinators.”

3. EPA Excerpt from the Problem Formulation : “MCPP -p DMAS is formulated as granular, water- soluble concentrate liquid, water soluble concentrate dry.”

Task Force Comment: Pressurized liquid and ready- to -use solution should be added to
read: “MCPP -p DMAS is formulated as granular, water-soluble concentrate liquid, water soluble concentrate dry, pressurized liquid (dispensed as foam) and ready- to -use solution.”

4. EPA Excerpt from the Problem Formulation : “MCCP

- p”

Task Force Comment : Please correct typographical error to read “MCPP

- p”.

5. EPA Excerpt from the Problem Formulation : “Given that MCPP -p is soluble in water there exists the potential to dissolve in runoff and puddles on the treated field may
contain the chemical.3

Task Force Comment : Punctuation would help clarify the meaning of the sentence. Also, a wording change is proposed in recognition that MCPP-p is primarily used on turf rather than fields: “Given that MCPP -p is soluble in water, there exists the potential to dissolve in runoff and thus puddles, if present on the treated turf, may contain the chemic al.”

6. EPA Excerpt from the Problem Formulation : “low octanol/water partitioning coefficient”

Task Force Comment : Suggest revision to read “low octanol/water partition coefficient”

7. EPA Excerpt from the Problem Formulation : “2 -methyl -4- chlorophonel”

Task Force Comment: Please correct spelling as follows: 2-methyl-4 -chlorophenol.

8. EPA Excerpt from the Problem Formulation : “The aquatic vascular and nonvascular plant species were most sensitive to MCPP-p DMAS, which caused significant effects to at all test levels that the NOAEC could not be established; the EC05 values were used instead.”

Task Force Comment : Suggest revision to: “The aquatic vascular and nonvascular plant species were most sensitive to MCPP-p DMAS, which caused significant effects at all test levels such the NOAEC could not be established; the EC05 values were used
inst ead.”

9. Page 39, A pp end ix A

– Bib liograp hy, MRID 0789601

Task Fo rce Comment: Pl ea se co rr ect the MRID to reflect 40789601. The perfor mi ng labo ra to ry is Hazleton Labo ra to ries Am er i ca , In c.

EFED Response: Comments #1-9 will be considered and typographical errors will be corrected
in future risk assessments.

SPECIFIC COMMENTS

1. Problem Formulation Page 13, Ta b le 5, A qu at ic P la nts, Nonvascu la r, Ma rine Diatom.
EPA Excerpt from the Problem Formulation:
Taxo n omic Gro u p S t u dy

T y pe Su rrogate

S p ec i es Toxi c ity

V al u e A c u te

Toxi c ity
C lassi f i c ation S o u r

c e ( S t u dy

c lassi f i c atio n )4

Aquatic Plants N

on v as c ular M

arine diatom ( S ke l e ton e ma

c ostatum) N OAEC =

< 0.009 mg

a. e ./ L ; I C 0 5

= 0.0008 mg

a. e ./ L ; I C 5 0 = 0.014 ( D M A S ) -- 42633902 43657303 ( A c c e ptabl e )

Task Fo rce Comment : We h ave si gnifi ca nt comments on this endpoint b eca use studies such as
those listed by EP A a s “ A cce ptable ” have f ace d considerable questions and cr iti cism in othe r regula to ry con texts. In a 2006 submission by the MCPP-p Task Fo rc e to EPA-SRR D (MRID
number 47008601 ), an o v er view docu ment identified and expla in ed the issu e s fa ced by multiple phenoxy compounds. The MCPP-p Task Fo rce ha s recently a tt empted to add re ss MCPP-p more sp ec ifi ca lly with the su bmission of a n ew MCPP-p Sk eletone ma study by t he
Task Fo rc e (MRID 49355201). The co n cer n facin g the different pheno xy task forces (MCPPp, 2,4 -DP-p, M CP A, M CP B and 2,4 -DB) is that some of the o rig in al studies identified in this

ov er vie w w ere conducted at a p ar ti cular labo ra to ry a cc ording to e ar li er guide lin e s (Subdivision J) and p re sent a pi c tu re of the to xicity of pheno xies to non-t ar get aqu a tic plants that is
in consistent with re sults obta in ed at many diff er ent contrac t resea rc h o rg anizations ( CR O) using the sa me or mo re cu r re nt guide lin e s.

Relevance of the New St ud y for No nvascular A qu at ic P la nt Toxicity of MCPP-p:

In comp ar ison to the 20 07 RED for MCPP-p, d a ta fr om the new study sh ow the 96 -Hour EC 5 0
for the m ar ine d iatom to be 83 mg ae /L vs 0.014 mg ae/L and the NO EC to be 32 mg ae /L vs <0.009 mg ae/L. The MCPP-p Task Fo rce regist ra n ts be li eve th at the older stu dy wa s flawed in

re sp ec t to havin g adequ ate growth of the test org anisms thereby ske wi ng the re sults low er

. Th erefo re , the new study should be re feren ce d for th e se endpoints.

Ex ce rpt of N

ew Stud y:
RESULTS

B i o l og ic a l P a r a m e t er B a s ed o n N o m i n a l C o ncen t r at i o ns ( m g M C PP

- p 4

a m in e / L )

E C 5 0 (95 % C o n f

idence
L i m i t s ) N O EC

96

- H o u r Yield 46 0 (31 0

- 5 7 0 ) 160

96

- H o u r A v e r a g e S p eci f ic Growth Rate 630 (59 0

- 6 7 0) 160

96

- H o u r A r ea U n d er t h e G ro w t h Curve 550 (42 0

- 6 5 0) 1605

B i o l og ic a l P a r a m e t er B a s ed o n M e a n M e a s ured C o ncen t r at i o ns ( m g M C PP

- p a. e

. / L )

E C 5 0 (95 % C o n f

idence L i m i t s ) N O EC

96

- H o u r Yield 83 (5 9

- 99 ) 32

96

- H o u r A v e r a g e S p eci f ic Growth Rate 110 ( l 1 0

- 12 0 ) 32

96

- H o u r A r ea U n d er t h e G ro w t h Curve 99 (7 6

- 12 0 ) 32

Ex ce rpt of MC

PP -p RE D:

T a ble 25

. S u m m a ry o f Aqu at ic P l a nt T o x ici t y D at a f o r M C P P

- p Species T o x ici t y E n d p o int M R 1 D

Va s c u lar p la n t, Lem n a g i bba E C 50 = 1. 3 m g ae / L

N O A E C < 0.4 4 m g ae / L
E C 05 = 0.2 3 m g ae / L F ro n d

n u m b er 424 8 62 0 1

N o nv a s c u lar p la n t, S kelet on ema c o s t a t um E C 50 = 0.01 4 m g ae / L

N O A E C < 0.00 9 m g ae/L
E C 05 = 0.000 8 m g ae / L C ell c ou n t d e n s i t y 426 3 39 0 2

436 5 73 0 3

mg ae/ L = m illi gram s of acid equivalent per l it er

With increasing e mp hasis and a tt ention on potential imp ac ts to endange re d sp ec ies, includin g possible indirec t ef

f ec ts to cr iti ca l habitat, there is a possibility th at some of the ph eno x y h er bic id es will be found to “ May Affec t” so me end angered sp ec ie s based on the alga d ata generated by one CR O that, based on the weight of the eviden ce, ap p ea r to be outli er s. Our

con c er n is it app ears th at no number of mo re recent studie s cond ucted to cu rrent guide lin es will

o ff set the se e ar li er results, ev en if th er e ar e st ark reasons to consider the initia l re sults, conducted to older guidel in es, high ly susp ec t or ind ee d invalid for current risk a ss e ssm ent

pu rpose s.

EFED Response: While the difference in results between the various studies is notable, EFED does not have information to explain the cause of the variation or to support that the earlier studies are scientifically invalid; however, for risk determination it is EFED policy to use the scientifically valid ecotoxicity study that provides the most conservative toxicity endpoints. For risk characterization, EFED considers the range of sensitivities among aquatic plants to evaluate whether one or all listed aquatic plants will be impacted when exposed. Also, the ECOTOX database or other sources of open literature will be looked at for other studies for consideration.

2. Problem Formulation Page 15, Ta b le 6, M am mal

– Chro nic, MRID 46591804
Task Fo rce Comment: The MCPP-p Task Fo rce do es not have a co py of the DER for this study. A re qu est for DE Rs was sent to Kaitlin Ke ll er on June 30, 2014.

EFED Response: The Health Effect Division (HED) reviews the 2-generation reproduction study with mammals. The Pesticide Re-Evaluation Division (PRD) will provide the available
DER for the requested study to the task force.6

3. Problem Formulation Page 15, Ta b le 6 a nd Pa ge 29, Ta b le 9, T erre strial P la nt s

– Veg eta tive Vigor, MRID 43059301
Task Fo rce Comment: EPA indi ca tes the study associated with MRID 43059301 is cla ssi fied as supplemental. The MCPP-p Task Fo rce rece iv ed a le tt er fr om EP A dated March 10, 1997
indi ca ting the Task Force “ submitted acce ptable information indi ca ting th at the 100%

ace tonitr ile solvent trea tm ent did not have any adv er se e ff ects on the ten crops te st ed.
Th er ef o re, the study (MRID 43059301) is upgrad ed to core and fulfills the guideline requi re ment 123-1b for MCPP-p Ac id.”

EFED Response: EFED will revise the study classification for MRID 43059301 from “supplemental” to “acceptable”.

4. Problem Formulation Page 22, Ta b le 7

Task Fo rce Comment: The MCPP-p Task Fo rce do es not have copie s of the DE R s for
the following studies. A requ est for the DE Rs wa s sent to E PA on June 30, 2014.

MRID 44110901

– Hy dr o lysis
MRID 42578101

– Special Dissociation S tu dy (D MA S )
MRID 44147001

– Photod eg ra d ation on Soil
MRID 44281301

– A er obic Soil Metabolism
MRID 42845301

– A er obic Aqua tic Metabolism
MRID 44205701

–

Leaching

– Adsorption/De so rption
MRID 42845302

–

Leaching

– Adsorption/De so rption MRID 43909701, 43909702, 43909703, 43909704, 43909705, 43943201

– Terre st ri al

Field Dissipation.

EFED Response: EFED will work with the Pesticide Re-Evaluation Division (PRD) to provide available DERs for the requested studies to the task force.

5. Problem Formulation Page 22, Ta b le 7, Guide li ne # 201 -1 and 201 -2, St ud y Classifica tion
Task Fo rce Comment: The entry in the cells is “ a ” whi ch ap p ear s to indica te th er e should be

a footnote to the table. Howev er , there is not a foo tnote. Pl ea se clarify.

EFED Response: The following footnote (Member of Spray-Drift Task Force) will be incorporated in future assessments.

6. Problem Formulation Page 31, 32 a nd 33; A pp e nd ix A

– Bibliography, MRID 40116101
Task Fo rce Comment: EPA lists MRI D 40116101 as the following:
TPH Committee (1986) Response to Data Call-in on Mecoprop of March 22, 1985: [To xicology
Dat a]. Unpublished compilation. 105 p.

The MCPP-p Task Fo rce indi ca tes MRID 40116101 has b ee n assigned to the following studie s:

Mun k, R. (198 6) Testing for Acute To xic ity in Fish

– MC PP (Mecoprop) to the Bluegill Sunfish7

(Lep omis mac ro chirus R

AF ). BASF Ak ti engese lls chaft Study Number 14F0047/83. 19 p.

Mun k, R. (198 6) Avian Single-Dose Oral LD50 of MCPP to the Bobwhite Quail (Colinus virginianus). BASF Ak ti eng ese lls chaft Study Numb er 11W0047/8372. 37 p.

EFED Response: The citations will be incorporated in future risk assessments.

7. Problem Formulation Page 31, A pp e nd ix A

– Bibliogra phy, MRID 42436701
Task Fo rce Comment: Th er e are two study numb er s included in the c it a ti o n for MRID 42436701. The appro pria te study number for this MRID is 119-002-03. The other study listed

– 119 -001-01

– was a ssi gned MRID 42435601.

EFED Response: EFED will correct the citation for MRID 42436701 using the study number
119 -002-03 and remove study number 119-001 -01.

8. Problem Formulation Pag es 75-109, A pp e nd ix D, Labe l u se info rma tion for M CCP -p (PC Code 129046); MC PP - p po tassium (PC Code 031503 ); MC PP -p (DMAS) (P C
code 031520)
Task Fo rce Comment: Our re view and comments at this time ar e limited to a subset of regist ra tions for which EPA ’ s ca lculation of an “ A.I. Maximum Appli ca tion Rate ” re sulted in
wh a t app eared to be an appli ca tion ra te th at is much larger th an the ra te ac tu ally st ated on the
lab e l. In our selected recalculations, we use the pounds per gallon of MCPP-p ac id equivalent

st ated on the lab e l as the st ar ting point. For example, if the lab el declares 0. 48 lb MCPP-p

ae /gal and the ra te is 2 gal/A, then the ae ra te is calculated a s follows:

0.48 lb ae /g al x 2 gal/A = 0.96 lb ae /A

Using this methodology, our ca lculations do not agree with those of EPA and we urge th e Ag en cy to re-eva lu a te th e ra tes in Appendix A, e sp ec ially for any ra tes that stand out as unusually h igh. Other sp ec if ic label int er p re tation considerations are also id entified in the

p ar ti cular examples below.

Problem Formulation Pag es 87-89, EPA Reg. No. 2217-639
Task Fo rce Comment: In multiple rows on this range of pages, E PA id en tifie s ra tes of:

2.5746325 lb/A foliar industrial
1.28731625 lb/A bro ad cast industrial
0.51200078 lb/A bro ad cast turf 0.49776109 lb/A spot trea tm ent turf

Th e se p re su mab ly re la te to the lab e l ra tes o f:

2.2 ga l/A foliar industrial
1.1 gal/A bro ad cast industrial
0.55 gal/A bro ad cast turf 0.4375 gal/A spot trea tm ent turf8

Howev er, when the Task Force calcula te s the ra tes using the MCPP-p content of 0.96 lb

ae /gal, we obtain va lu es of:
2.112 lb ae /A foliar indu st rial
1.056 lb ae /A broad ca st industrial
0.528 lb ae /A broad ca st turf
0.42 lb ae /A spot trea tm ent turf

N ear ly all of the se rate s are low er than those ca lculated by EP A.

Problem Formulation Page 98, EPA Reg. No. 2217-961
Task Fo rce Comment: In multiple rows, EPA i dentifie s ra tes of:

0.3733847 lb/A broad ca st nonagricultu ra l 1.71687572 lb/A spot trea tm ent nonagricultural 0.36486153 lb/A spot trea tm ent turf
0.33508883 lb/A bro ad cast turf

Th e se p re su mab ly re la te to the lab e l ra tes of: 0.4875 gal/A bro adcast nonagricultu ra l 0.49125 ga l/A spot treatment nonagricultu ra l 0.488 gal/A spot trea tm ent turf 0.4875 gal/A bro adcast turf

Howev er, when the Task Force calcula te s the ra tes using the MCPP-p content of 0.655 lb

ae /gal, we obtain va lu es of:

0.319312 lb ae /A broadcast nonagricultu ra l
0.321768 lb ae /A spot trea tm ent nonagricultu ra l
0.31964 lb ae /A spot t re a tm ent turf
0.319312 lb ae /A broadcast turf

The Task Force ca lculations a ll re su lted in lower ra tes than those of EPA. Also, the labeled
maximum annu a l appli ca tion ra te for spot trea tm ent on nonagricultu ra l land for this registration is 6 pts/A, which is equivalent to only 0.49125 lb MCPP-p ae . A ra te of ov er 1.7 lb/A as shown
in EPA ’ s table is not allowed by the lab e l.

Problem Formulation Pag es 101-102, EPA Reg. No. 228-217
Task Fo rce Comment: Among the st ated “ Use Re st ric tions” for the entire lab el is: “ Do not

app ly mo re th an 4.4 gallons of p rodu c t (1.5 lb M CP A)/ ac re per ye ar

. ” S in ce the MCPP-p
content for this product is 0.17 lb ae /gal, the maximum p er missible MCPP-p ra te und er this use

re st riction is: 4.4 gal x 0.17 lb ae /gal = 0.748 lb ae/A. Even if this re st riction was re vised to be a limit per appli ca tion inst ea d of an annual limit (a s a r ec ent cl ar ifying int erp retation of the
M CP A RED states), the MCPP-p ra te for a si ng le application would not ex cee d 0.748 lb ae /A.

In multiple rows, EPA i dentifie s ra tes of:

0.00080019 lb /30 fl oz spot trea tm ent nonagricultu ra l9

0.819 lb/A bro ad ca st nonagricultu ra l 17.84407666 lb/A spot tr ea tm ent turf
0.17425811 lb/A bro ad cast tu rf

. 1.24798563 lb/A spot trea tm ent re sidential la wn 0.878715 lb/A bro ad ca st re sidential la wn

Th e se p re su mab ly re la te to the lab e l ra tes of: 3 tsp produ ct/30 fl oz water (f or individual/small area s of weeds) spot trea tm ent nonagricultu ra l 4.4 gal/A broadcast nonagricultural

3 tsp produ ct/2 qt water /100 sq f t (or for individu al/sma ll areas of w ee ds) spot trea tm ent turf 4.4 gal/A bro ad cast turf 10.5 tsp produ ct/2 qt water (f or individual/sma ll areas of w ee ds) spot

treatment re sidential lawn 1.5 gal/A bro ad cast re si dential la wn

Howev er, when the Task Force calcula te s the ra tes using the MCPP-p content of 0.17 lb

ae /gal, we obtain va lu es of:

0.000664 lb ae /30 fl oz (f or individual/sma ll areas of w ee ds) spot trea tm ent non agricultu ra l
0.748 lb ae /A broad ca st non agricultu ra l
0.000664 lb ae /2 qt water (f or individual/sma ll ar eas of weeds) spot trea tm ent turf
0.748 lb ae /A broad ca st tu rf
0.0023242 lb ae /2 qt water (f or individual/sma ll areas of w ee ds) spot treatment re sidential lawns
0.255 lb ae /A broad ca st residential lawns

The EP A ca lculated ra te of 17.84407666 lb/A is high ly in consistent with lab el info rmation and
should not be used for risk a ss e ssm ent. Howev er , we ac kno wl edge th at there are oppo rtunitie s to improve cl ar ity of label lan guag e.

Problem Formulation Page 10 6, EPA Reg. No. 228 -513
Task Fo rce Comment: The maximum lab e l ra te for spot trea tm ent on lawns and turf is 13.5 pints
of p roduct per ac re , which is equivalent to only 1.198 lb ae /A of MCPP-p. In cont ra st, EPA ’ s table id entifies a ra te of 60.82840701 lb/A. This ra te is high ly in consistent with the lab e l and
should not be used for risk a ss e ssm ent. It is ac knowledged that the labe l could be mo re cle ar , but
the sense of the label is that the ra tes g iv en in pints ar e exp re ss ed on a per acre basis and rates

g iv en in fluid oun ce s are exp re ss ed on a p er 1000 squ ar e foot basis. P er hap s a point of confusion
is that d ec im al points in some of the ra te s s ee m to be ill egible in the EP A sta mp ed ac ce pted
labe l.

EFED Response: EFED will work with the Biological and Economic Analysis Division (BEAD) of OPP to update the use summary tables at the time of risk assessment. Additionally, the Agency may request that registrants and/or the MCPP-p Task Force provide a use pattern summary table which includes this type of application information.10



# The San Francisco Bay Regional Water Quality

Control Board Comments

For the MCPP registration, we support the aquatic toxicity data requests laid out in EPA’s Environmental Fate and Effects Division’s (EFED) Problem Formulation dated June 2, 2014. We urge EPA to amend the MCPP-p Registration Review Work Plan to require data to fill the data gaps identified by EFED, specifically: • Estuarine/marine invertebrate acute toxicity • Estuarine/marine fish acute toxicity • Freshwater fish early -life stage.

In addition, we strongly encourage EPA to request data for fate and aquatic toxicity for the degradate 2-methyl-4 -chlorophenol. As stated in the EFED Problem Formulation, information from the Pesticide Properties Database indicates that this degradate is more toxic to aquatic invertebrates and fish than the parent compound.

We strongly encourage EPA to consider the cumulative risk of additive toxicities, both between MCPP-p and its degradates and also between these herbicides and other pesticides.


# California Central Valley Regional Water Quality

Control Board Comments

In order to prevent water quality impairments caused by MCPP-p we are requesting the following additions to the registration review workplan:

 Require the necessary ecological effects data for risk assessment identified in the EFED probl em formulation:

o Estuarine/marine invertebrate acute toxicity.

o Estuarine/marine fish acute toxicity.

o Freshwater fish early-life stage.

 Consider the cumulative risk of additive toxicities between MCPP-p, other phenoxy herbicides, and their common and toxic degradates (e.g., 2 -methyl-4-chlorophenol )

.

EFED Response: EFED appreciates the comments from the San Francisco Bay Regional and California Central Valley Regional Water Quality Control Boards (collectively CA WQCB) suggesting that OPP require data tested with the parent compound (estuarine/marine invertebrate acute toxicity, estuarine/marine fish acute toxicity, and freshwater fish early-life stage) to fill the data gaps needed for a complete ecological risk registration review. While no specific risk concern was cited by either CA WQCB other than the potential for water quality impairments; EFED does agree that there is a potential for exposure to freshwater and estuarine/marine organisms from MCPP-p use. While the aquatic studies for the parent compound were identified as data gaps in the problem formulation, EFED is not requiring the estuarine/marine studies11

given the lines of evidence indicating th at exposure estimates from the Reregistration Eligibility
Decision for the parent compound are one to two orders of magnitude below known toxicities of chlorophenoxy herbicides to freshwater organisms. It is assumed the estimated environmental

exposures for MCPP-p would be at least an order of magnitude below the toxicity of the parent compound to estuarine/marine organisms. Also, a daphnid chronic study is available, with an uncertainty introduced, which can be used to calculate an ACR (Acute- to -Chronic Ratio) to estimate a chronic value for freshwater fish in lieu of an 850.1400 freshwater fish early-life stage study. Thus, requiring the aquatic studies is of low value to the ecological risk assessment because the potential for exposure is anticipated to be low.

In addition, exposure estimates and toxicity of the degradates have not been included in past

assessments for MCPP-p . If exposure and/or toxicity of the degradates are significant, then the risks to potentially exposed organisms could be underestimated. A review of the Pesticide Properties Database ( http://sitem.herts.ac.uk/aeru/ppdb/en/Reports/876.htm ) indicates the aquatic toxicity data for the degradate 2-methyl-4-chloropheno l on bluegill sunfish, daphnia magna, and lemma gibba are available and should be submitted to the Agency for a formal in-house review to determine whether the data is acceptable for use in the risk assessmen t. Upon further investigation, these studies with the degradate were in the ECOTOX database. The studies with the bluegill sunfish and daphnia magna will be pulled by EFED and reviewed for consideration. However, the study with the lemna gibba is from an unknown source, and any additional information on the source/content of that lemna gibba study would be helpful. The citations for the bluegill sunfish and daphnia magna are as follows:

ECOTOX Reference Number: 5590

Author(s): Buccafusco,R.J., S.J. Ells, and G.A. LeBlanc

Publication Year: 1981

Title: Acute Toxicity of Priority Pollutants to Bluegill (Lepomis macrochirus)

Source: Bull. Environ. Contam. Toxicol.26(4): 446

- 452

ECOTOX Reference Number: 5184

Author(s): LeBlanc,G.A.

Publication Year: 1980

Title: Acute Toxicity of Priority Pollutants to Water Flea (Daphnia magna)

Source: Bull. Environ. Contam. Toxicol.24(5): 684

- 691

EPA appreciates the need to address cumulative risk from mixtures of pesticides both within and across modes of action. EPA, FWS, and NMFS collectively engaged the National Academy of Sciences (NAS) on the issue of mixtures as part of the broader approach to conduct ESA compliant pesticide risk assessments. As noted by the NAS report, the ability to quantitatively assess risk from mixtures (tank mixes, formulated product, and environmental) is perhaps the

most daunting challenge facing EPA and the Services. EPA currently considers cumulative mixture toxicity where data are available on combined effects from one or more compounds.
EPA acknowledges that mixtures represent a consideration that may influence the toxicity of the12

active ingredient; however, there are many uncertainties and limitations to quantitatively assessing the impact of mixtures on the overall risk picture. As the NAS noted, there are significant challenges to incorporation of mixtures analyses into the risk assessment process including the lack of a generic peer-reviewed method to assess the risks from mixtures, uncertainty on the temporal aspects of exposure to mixture constituents (e.g. each constituent behaves differently once in the environment), lack of knowledge about mechanism of action in

non -targets, and uncertainty on the portability of observed interactions across taxa. EPA and the Services have made the issue of developing an approach for assessing mixtures toxicity a priority
for future risk assessments.13



### Addendum to Data Gaps Identified in the Problem Formulation

The Problem Formulation requested three studies to evaluate the potential for MCPP-p to adversely affect pollinators: a honeybee adult acute oral toxicity study (following OECD 213), a honeybee adult 10-day chronic oral (special study), and a honeybee larval repeated dose study (special study renamed as honeybee larval chronic oral toxicity study). However, EFED policy on pollinator protection has recently been updated 1

. Thus, justifications are provided below for
the following Tier I bee studies:

 Acute oral toxicity to adult honey bees

 Acute oral toxicity to larval honey bees

 Chronic oral toxicity to adult honey bees

 Chronic oral toxicity to larval honey bees

While the larval acute oral toxicity study (following OECD 237) was not specified in the MCPPp Problem Formulation, the release of the new pollinator guidance requires that this study should be conducted to support the MCPP-p risk assessment. Note that it is possible to conduct the larval chronic oral study in such a way as to derive both an LD 50 (acute endpoint of interest) and a NOAEC (chronic endpoint of interest) from a single study. If the chronic larval toxicity study is conducted in such a way that it derives both an LD 50 and NOAEC, then a separate acute larval toxicity study is not needed. For pollinator studies without finalized OECD guidelines, protocols should be submitted for EPA review and comment prior to study initiation.

The need for higher Tier semi-field and full field pollinator studies for MCPP-p will be
determined after review of these Tier I studies.



### Data Justifications

Guideline Number: Special Study Study Title: Adult Honey Bee Acute Oral Toxicity
Rationale for Requiring the Data
This study is needed for the assessment to evaluate risks to honey bees if the registered uses of MCPP

- p will result in adverse effects to honey bee s or other insect pollinators

. R egistered non

- agricultural use sites of MCPP

- p include: nonagricultural areas, uncultivated areas/so il s (i.e., roadsides and rights

- of

way) , ornamental lawns and turf (i.e. golf courses, cemeteries, parks, sports fields, turfgrass, lawns, a nd other grass areas), and sod farms

. Therefore, MCPP

- p residues may result in exposure to foraging bees

. Residues can in turn be brought back to bee colonies where in

- hive bees including young adult and developing brood ( i.e. , eggs, larvae and pupae) may be exposed. Therefore, exposure at all bee life stages would be expected and may extend for chronic exposures.

1 (Guidance for Assessing Pesticide Risks to Bees, 06.23.2014; signed by Donald Brady, Director, EFED; http://www2.epa.gov/sites/production/files/2014- 06/documents/pollinator_risk_assessment_guidance_06_19_14.pdf )14

Guideline Number: Special Study Study Title: Adult Honey Bee Acute Oral Toxicity
Rationale for Requiring the Data

Since the Problem Formulation for MCPP

- p w as signed, the Agency finalize d its framework to assess risk to pollinators (USEPA, 2014). EPA now requires this study for all use sites where potential exposure to pollinators may occur. Registrants may request a waiver of the study if use practices significantly restrict exposure of the pesticide to bees.

Although EPA has not developed a guideline for this study, the acute (single dose) adult toxicity study following OECD TG213 provides acute oral toxicity data on adult bees and may be used to satisfy the requirement for acute oral toxicity to adult bees

. At this time, EFED is asking that a protocol for the study be submitted beforehand to increase the likelihood of an acceptable study submission.

Practical Utility of the Data
How will the data be used and how could the data impact the Agency’s future decision

- making?

The acute toxicity study with young adult bees provides median lethal dose (LD 50 ) value for honey bees ( A. mellifera ) based on acute oral exposure. These data a re used in conjunction with acute contact LD 50 data obtained through OCSPP 850.3020 to estimate the acute toxicity of technical grade active ingredient (TGAI) to individual young adult honey bees. The studies also provide slopes for the dose

response curv es that can in turn be used for estimating the likelihood of individual effects and sublethal effects observed in the study will be used to further characterize effects observed following a single exposure to the technical grade material. Data obtained fr om this study will be used in estimating acute
risk to individual adult bees. Risk estimates based on these data will be considered along with other lines of evidence to determine whether higher

- tier studies are needed at the whole colony level.

These dat a are needed for the registration review risk assessment and for future endangered species assessments. The data would allow the Agency better characterize the potential for risk to insects (including beneficial pollinators) from the use of MCPP

- p . Th ese data will help the Agency determine whether any mitigations are needed. If the registration review and any future endangered species risk assessments are performed without these data, the Agency would have to assume that MCPP

- p "may affect" insects, inclu ding bees and beneficial pollinators, directly (and endangered species from other taxa indirectly), and uses of MCPP

- p might need to be restricted in areas where pollinators could be exposed.

Guideline Number: Special Study Study Title: Adult Honey Bee Chronic Oral Toxicity
Rationale for Requiring the Data
This study is needed for the assessment to evaluate risks to honey bees if the registered uses of MCPP

- p will result in adverse effects to honey bee s or other insect pollinators

. R egistered non

- agricultural use sites of MCPP

- p include: nonagricultural areas, uncultivated areas/so il s (i.e., roadsides and rights

- of

way) , ornamental lawns and turf (i.e. golf courses, cemeteries, parks, sports fields, turfgrass, lawns, and other grass a reas), and sod farms

. Therefore, MCPP

- p residues may result in exposure to foraging bees

. Residues can in turn be brought back to bee colonies where in

- hive bees including young adult and15

Guideline Number: Special Study Study Title: Adult Honey Bee Chronic Oral Toxicity
Rationale for Requiring the Data
developing brood ( i.e. , eggs, larvae and pupae) may be exposed. Therefore, exposure at all bee life stages would be expected and may extend for chronic exposures.

Since the Problem Formulation for MCPP

- p w as signed, the Agency finalize d its framework to assess risk to pollina tors (USEPA, 2014). EPA now requires this study for all use sites where potential exposure to pollinators may occur. Registrants may request a waiver of the study if use practices significantly restrict exposure of the pesticide to bees.

Although EPA ha s not developed a guideline for this study and OECD has yet to finalize test guidance for chronic studies, efforts are currently underway to develop standardized guidelines for assessing effects from chronic (10

- day) exposures to adult bees in the laborato ry. At this time, EFED is asking that a protocol for the study be submitted beforehand to increase the likelihood of an acceptable study
submission.
Practical Utility of the Data
How will the data be used and how could the data impact the Agency’s future decision

- making?

The 10

- day toxicity study with young adult bees provides no

- observed adverse effect level (NOAEL) and
lowest

- observed adverse effect level (LOAEL) for assessing potential chronic effects. Data obtained from this study will be used in estimating chronic risk to individual adult bees. Risk estimates based on these data will be considered along with other lines of evidence to determine whether higher

- tier studies ar e needed at the whole colony level.

These data are needed for the registration review risk assessment and for future endangered species assessments. The data would allow the Agency better characterize the potential for risk to insects (including benefici al pollinators) from the use of MCPP

- p . Th ese data will help the Agency determine whether any mitigations are needed. If the registration review and any future endangered species risk assessments are performed without these data, the Agency would have to assume that MCPP

- p "may affect" insects, including bees and beneficial pollinators, directly (and endangered species from other taxa indirectly), and uses of MCPP

- p might need to be restricted in areas where pollinators could be exposed.

Guideline Number: Non

- Guideline Study Title: Larval Honey Bee Acute and Chronic Oral Toxicity Rationale for Requiring the Data This study is needed for the assessment to evaluate risks to honey bees if the registered uses of MCPP

- p will result in adverse effects to honey bee s or other insect pollinators

. R egistered non

- agricultural use sites of MCPP

- p include: nonagricultural areas, uncultivated areas/so il s, so il s (i.e., roadsides and rights

of

- way) , ornamental lawns and turf (i.e. golf courses, cemeteries, parks, sports fields, turfgrass, lawns, and other grass areas), and sod farms

. Therefore, MCPP

- p residues may result in exposure to foraging
bees . Residues can in turn be brought back to bee colonies where in

- hive bees including young adult and developing brood ( i.e. , eggs, larvae and pupae) may be exposed. Therefore, exposure at all bee life stages would be expected and may extend for chronic exposures.16

Guideline Number: Non

- Guideline Study Title: Larval Honey Bee Acute and Chronic Oral Toxicity Rationale for Requiring the Data
Since the Problem Formulation for MCPP

- p w as signed, the Agency finalize d its framewo rk to assess risk to pollinators (USEPA, 2014). EPA now requires this study for all use sites where potential exposure to pollinators may occur. Registrants may request a waiver of the study if use practices significantly restrict exposure of the pestici de to bees.

Although EPA has not developed a guideline for this study, the 21

- day larval toxicity study currently under development by OECD provides both acute and chronic oral toxicity data on developing bee brood and (when this guidance is finalized) ma y be used to satisfy the requirement for both acute and chronic oral toxicity to honey bee larvae. Registrant may submit a separate acute (single dose) larval toxicity study following OECD TG237 as well as the 21

- day repeat dose chronic toxicity study.

Practical Utility of the Data
How will the data be used and how could the data impact the Agency’s future decision

- making?

The 21

- day larval toxicity study under development by OECD provides both acute and chronic toxicity data on developing bee brood and will yield a median lethal dose (LD 50 ) for assessing acute toxicity during the early part of the study as well as a 21

- day no

- observed adverse effect level (NOAEL) and lowest

- observed adverse effect level (LOAEL) for assessing chronic effects. Effects on survival and development (adult bee emergence) from repeat exposures to the active ingredient will be used in estimating chronic risk to individual brood. Risk estimates based on these data will be considered along with other lines of evidence
to dete rmine whether higher

- tier studies are needed at the whole colony level.

These data are needed for the registration review risk assessment and for future endangered species assessments. The data would allow the Agency better characterize the potential for risk to insects (including beneficial pollinators) from the use of MCPP

- p . Th ese data will help the Agency determine whether any mitigations are needed. If the registration review and any future endangered species risk assessments are performed without t hese data, the Agency would have to assume that MCPP

- p "may affect" insects, including bees and beneficial pollinators, directly (and endangered species from other taxa indirectly), and uses of MCPP

- p might need to be restricted in areas where pollinators could be exposed.