2 In response, the Agency acknowledges that an ecological risk as sessment was completed in

absence of these data . However, the Agency clearly identified uncertainty in this risk assessment

due to the lack of sediment toxicity data. Specifically, the registrant submitted only one sediment toxicity study (28

- d midge chr onic toxicity; MRID 48250425) which was classified as supplemental because it only evaluated organism emergence and development rate (and not reproduction) . The Agency further noted in its ecological risk assessment (D408705) chronic sediment toxicity dat a were lacking for two other species that are typically required ( 1 freshwater

and 1 estuarine/marine amphipod).

To further characterize and address this uncertainty for the purposes of this action, the Agency has applied toxicity extrapolation methods based on the chronic toxicity of tolfenpyrad to
freshwater and estuarine/marine invertebrates exposed in the water column. The results of this analysis, in addition to results using the aforementioned sediment toxicity study, are shown in

Table 1 below fo r the proposed use with the highest EECs in pore water (GA Pe a c h ).

Table 1 . Estimated Risk Quotients for Benthic Invertebrates with the Proposed New Uses of Tolfenpyrad

21

- d Pore Water EEC (μg a.i./L) (1) Invertebrate

Chronic NOAEC (μg a.i./L) Toxicity Ba sis Species/MRID Chronic

Benthic

Invertebrate RQ

0. 1 4 0.0288 Sediment pore

water Chironomus riparius (48250425) 4

. 8 ( 2 )

0. 1 4 2.3 Water column Americamysis

bahia (48250420) 0. 0 6

0. 1 4 0.244 Water column Daphnia magna ( 48250418) 0. 6

(1) EEC in sedi ment pore water based on PRZM/EXAMS modeling for GA Pecan crop scenario (see Table 3.5 of D408705) (2) Exceeds chronic risk level of concern of 1.0. T h e c hronic NOAEC from this study does not include measurement of reproductive effects.

The results of this a nalysis indicate that the proposed uses of tolfenpyrad have the potential for chronic risk to benthic invertebrates, based on a chronic RQ of 4

. 8 for C. riparius . There is uncertainty associated with this RQ because effects on reproduction was not assessed in the applicable toxicity study. If effects of tolfenpyrad on C. riparius reproduction occur at lower concentrations than those on development rate and emergence, the chronic risk quotient will be greater than 4

. 8 . On the other hand, the NOAEC from the C. riparius study represents the highest concentration tested (i.e., a LOAEC was not achieved in this study). Therefore, it is also possible that the RQ may be lower than 4

. 8 had higher concentrations been tested. For the mysid ( A. bahia ) and the daphni d ( D. magna ), chronic risks based on pore water exposure do not

exceed the chronic risk level of concern (1.0). U n c e r t a i n t y a s s o c i a t e d w i t h t h e s e R Q v a l u e s3 r e l a t e t o t h e p o s s i b i l i t y t h a t f r esh w a t e r a n d e s t u a r i n e / m a r i n e a m p h i p o d s u s e d i n s e d i m e n t t o x i c i t y

t e s t i n g m a y b e m o r e o r l e s s s e n s i t i v e t o t o l f e n p y r a d c o m p a r e d t o d a p h n i d s a n d m y s i d s

.

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, E F E D b e l i e v e s t h a t s u f f i c i e n t i n f o r m a t i o n

e x i s t f r o m w h i c h t o a s s e s s r i s k s t o b e n t h i c i n v e r t e b r a t e s f o r t h e p r o p o s e d u s e s o f t o l f e n p y r a d

. H o w e v e r
, i n o r d e r t o a d d r e s s t h e a f o r e m e n t i o n e d u n c e r t a i n t i e s
, E F E D s t r o n g l y r e c o m m e n d s t h a t

a d d i t i o n a l s e d i m e n t t o x i c i t y d a t a b e s u b m i t t e d t o t h e A g e n c y f o r a n y n e w u s e s o f t o l f e n p y r a d i n

t h e f u t u r e

.