UNI T ED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON

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. C

. 20460

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

MEMORANDUM

DATE: June 30, 2014

SUBJECT: Addendum to the risk assessment for the proposed new use of spirotetramat on lawns and turf in a formulated product (12ESP703 SC Insecticide) with imidacloprid (PC 392201; DP Barcode 413577) 

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Joseph DeCant,

. Ecologist 

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# ~ FROM: Environmental Risk Branch 5 

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Environmental Fate and Effects Division (7501P) 

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THROUGH: Mah T

. Shamim, Ph.D, Branch Chief Environmental Risk Branch 5 Environmental Fate and Effects Division

TO: Rita Kumar, Risk Manager Reviewer Reuben Baris, Risk'Manager #07 Insecticide and Rodenticide Branch Registration Division (7505P)

The Environmental Fate and Effects Division (EFED) completed a risk assessment for

. the proposed new use of spirotetramat on turf and lawns in a formulated product with imidacloprid in February of 2014 (D413577). In the risk assessment, EFED highlighted the risk associated with the use of spirotetramat alone on 

## turf and lawns as well as these risk concerns in light of the overall risk picture associate d with the proposed formulated product. This addendum provides further detail in terms of the differentiation between the risk picture associated with the proposed use of spirotetramat on turf and lawns within the context ofthe proposed formulated product, as well as corrections to the risk profile of the formulated product.

The risk assessment (D413577) contains a table that illustrates the risks associated with spirotetramat alone compared to the overall risk picture of the formulated product based on previous assessments of both spirotetramat and imidacloprid that evaluated use rates similar to the
rates in the proposed formulated product. This addendum provides a revised Table 1 that illustrates this compar i son in the risk profiles and updates some of the risk conclusions associated with the formulated product based on previous risk assessments. When comparing the risk profiles, it is evident that the formulated product has a much broader risk profile than spirotetramat alone. The r isk profile for the formulated product is primarily driven by the inclusion of

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imidacloprid in the formulated product. Imid acloprid is already registered on turf, and the first EFED risk assessment for turf and lawn uses related to imidacloprid was conducted in 1993 (D179364) at a maximum rate of 0.5 lb a.i./A, which is the currently proposed rate. However, EFED methods have evolved considerably since the first assessment, and so the contribution of imidacloprid to the risk profile of the formulated product is a function of a more recent assessment as the original assessment on turf and lawns did not capture the entire risk pi cture of imidacloprid

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Table 1 . Summary of e nvironmental risk conclusions for various taxa exposed to

s pi rotetramat alone and the formulated product for the p r oposed u se on turf and lawns.

Assessment Endpoint Identified Risk of Concern with Spirotetramat Alone Identified Risk of Concern with the Formulation

Acute and Chronic Risk to Freshwater and Estuarine/marine Fish None None

Acute and Chronic Risk to Freshwater and Estuarine/Marine Invertebrates None Acute and Chronic risk to freshwater and estuarine/marine invertebrates

Aquatic Benthic Invertebrates None Acute and Chronic risk to freshwater and estuarine/marine benthic invertebrates
Aquatic Non

- Vascular and Vascular Plants None None

Acute and Chronic Risk to Birds Chronic risk to birds Chronic risk to birds (see description below for more information regarding the uncertainty in this conclusion) *
Acute and Chronic Risks to Mammals None Acute risk to mammals **

Risks to Upland and Wetland Plants None None

Risk to Pollinating Bees Risk to pollinating bees Risk to pollinating bees

*In the risk assessment (D413577), the risk summary stated that risk of concern related to acute and chronic risk to birds. However, the risk of concern for spirotetramat and imidacloprid based on previous assessments at the proposed maximum application rates is only for chronic risk. **In the risk assessment (D413577), the risk summary stated that the risk of concern related to chronic risk to mammals. However, the risk of concern relates to acute risk to mammals based on a previous assessment of imidacloprid at the maximum use rate of 0.5 lb a.i./A.



### This first risk assessment for imidacloprid on turf (D179364) found risk of concern to aquatic invertebrates, birds, and fish. It is important to note that the risk for fish was derived from the uncertainty associated with a lack of data on chronic toxicity of imidacloprid to fish. Since this assessment, the regis trant has submitted additional data on the chronic toxicity of imidacloprid to fish that shows low toxicity on a chronic basis. Consequently, there is no chronic risk of concern to fish from the formulated product.

In contrast, the risk s of concern to avian and aquatic invertebrate species remain for the proposed formulated product. The risk of concern to aquatic invertebrates associated with the formulated

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product is also driven solely by imidacloprid at the proposed use rates

. S pirotetramat contribu tes to the risk to birds as its chronic toxicity presents a risk of concern based on a previous assessment (D398764, banana/plantain use) that assessed an application rate similar to the currently proposed
use rate

. A more recent evaluation of imidaclopri d on caneberry (D334030+) at 0.5 lb a.i./A corroborates the concern for birds from the original assessment of imidacloprid use on turf and employed updated terrestrial modeling methods. The presence of imidacloprid as it relates to food avoidance may atte nuate this risk from spirotetramat, though there is some uncertainty in this conclusion. The uncertainty in the conclusion on avoidance derives from the high acute toxicity of imidacloprid

, yet avoidance behavior is evident in the dietary toxicity studies with imidacloprid. A s noted in the imidacloprid assessment (D334030+)

, the avoidance of birds to imidacloprid treated food items is a learned response mediated by post

- ingestional distress

. In other words, birds will initially feed on imidacloprid contam inated food items that lead to a toxic response. If the birds survive, they stop feeding on the contaminated food. In addition, incidents related to imidacloprid have been recorded of secondary toxicity to birds whereby surfaced dead grubs appeared to ha ve been eaten by birds, resulting in the death of several young and adult robins. Consequently, it appears that dose and tolerance of the bird to an initial consumption of imidacloprid may determine the potential for mortality to birds that consume food it ems contaminated by the formulated product where both spirotetramat and imidacloprid are toxic to birds. It seems then that imidacloprid likely drives the risk of concern for birds as well with this formulated product, either leading to avoidance or morta lity depending on the dose of imidacloprid and the initial tolerance of the bird.

The updated risk assessment for imidacloprid on caneberry (D334030+) also differed from the original assessment of imidacloprid on turf for mammals. This assessment on cane berry, using updated terrestrial modeling methods, found acute risk to mammals at the maximum application rate of 0.5 lb a.i./A, which is the same application rate in the proposed formulated product. Consequently, imidacloprid also drives the risk to mamm als for the proposed formulated product with both spirotetramat and imidacloprid. In terms of synergy between spirotetramat and imidacloprid, EFED evaluated the acute oral toxicity data related to mammals for the formulated product (MRID 48977303) relativ e to t he data for spirotetramat alone. The acute oral LD 50 

### for spirotetramat technical is >2000 mg a.i./kg, whereas for imidacloprid technical the LD 50 

### is 424 mg a.i./kg and more closely matches the toxicity of the formulated product (500 mg/kg) . The data on the formulated product combining both spirotetramat and imidacloprid therefore does not show synergy related to acute mammalian toxicity but rather confirms that the risk to mammals is likely driven by imidacloprid in the formulated product.

In summary, the risks of concern contributed by spirotetramat alone in the formulated product, as noted in D413577

, relate to chronic risk to birds and risk to pollinating bees and potentially other beneficial arthropods. The risks of concern for other taxa, and likely the concern for birds as well, associated with the formulated product highlighted in Table 1 , however, are driven by imidacloprid.