  SEQ CHAPTER \h \r 1 

	August 6, 2002

MEMORANDUM

SUBJECT:	Tolerance Petition for Uses of Deltamethrin (PC Code 097805) on
Field Corn, Sorghum, Soybeans, Sunflowers, Bulb Vegetables, Cucurbit
Vegetables, Leafy Vegetables, Fruiting Vegetables, Carrots, Potatoes,
Radishes, Artichokes, Cauliflower, Broccoli, Cabbage, Mustard Greens,
Tree Nuts, Stone Fruits, and Pome Fruits (DP Barcode D262498)
Incremental Ecological Effects Risk Assessment Due to the New Uses
Review of an Aquatic Metabolism Study of Deltamethrin, and a Batch
Equilibrium Study of m-Phenoxybenzoic Acid, a Major Degradate of
Deltamethrin.

FROM:	Miachel Rexrode, Ph.D., Senior Aquatic Biologist

		José Luis Meléndez, Chemist

		ERB V/Environmental Fate and Effects Division (7507C)

THROUGH:	Mah T. Shamim, Ph.D., Chief

		Environmental Risk Branch V

		Environmental Fate and Effects Division (7507C)

TO:		George LaRocca, PM,

		William Sprout, PM Team Reviewer

		Registration Division (7505C)

This memo presents an incremental Ecological Effects Risk Assessment for
the use of deltamethrin.  The registrant seeks to establish tolerances
for the use of the chemical on field corn, sorghum, soybeans,
sunflowers, bulb vegetables, cucurbit vegetables, leafy vegetables,
fruiting vegetables, carrots, potatoes, radishes, artichokes,
cauliflower, broccoli, cabbage, mustard greens, tree nuts, stone fruits,
and pome fruits.

In addition, this memo presents the review of two laboratory studies
submitted by the registrant: an Aquatic Metabolism study for
deltamethrin, and a Batch Equilibrium study for m-phenoxybenzoic acid, a
major degradate of deltamethrin.

RESULTS:

Incremental Ecological Effects Risk Assessment for the New Uses of
Deltamethrin

Deltamethrin is highly toxic to exposed aquatic organisms or nontarget
beneficial insects.  The prescribed use patterns have the potential for
chronic exposure and harm to fish and aquatic invertebrates, specially
those living in or near the benthos (since deltamethrin is accumulated
in the sediment).  Many use areas are expected to be located adjacent to
some types of aquatic habitats.  Drift may be harmful to both beneficial
insects and aquatic impact.  The problem of endangered species should be
addressed on a site by site basis.  Deltamethrin appears to be immobile,
relatively persistent in the environment, stable to hydrolysis and
photolysis, and very lipophilic.

EFED conducted previously a Risk Assessment for the use of deltamethrin
on Cotton (DP Barcode D188115, 01/17/94).  The proposed application rate
for cotton was 0.020 lb a.i./A to a maximum of 0.2 lb a.i./season.  The
worst case scenario, including the new uses in the application of
deltamethrin on broccoli, coliflower, cabbage, and mustard, where the
proposed application rate is 0.028 lb a.i./A applied up to 8 times or
0.22 lb a.i./A.  EFED believes that the ecological risk posed by the new
uses of deltamethrin is similar to the use on cotton, previously
assessed.  A new full scale assessment will not be conducted until such
time that the EFED can fully revise new ecological effects data.  In the
meantime, the Division will rely on the previously released Risk
Assessment.

Review of the Two Studies Submitted by the Registrant

162-3/4  Aerobic/Anaerobic Metabolism of Deltamethrin (MRID# 44977005)

This study provides marginal supplemental information about the aquatic
metabolism of deltamethrin in an aerobic water and anaerobic sediment
system.  There were various deficiencies found in the system, including
the fact that the system was not completely aerobic or anaerobic, the
analytical method could not distinguish deltamethrin from its primary
α-R-isomer, there is an unexplained steady decline in the material
balance to 80-87% at the last test interval, and radioactive material
may have been adhered to the walls of the vessels and the methodology
could not account for that fact.

163.1	Adsorption and Desorption of  14C-m-Phenoxybenzoic Acid in Four
Soils (MRID# 44977006)

This study may be considered acceptable and it provides partial
information towards the fulfillment of the mobility data requirement for
deltamethrin.  The study provides information about the mobility of a
major degradate of deltamethrin, m-phenoxybenzoic acid.  Some details of
the study are not clear and the registrant is required to submit
additional information to clarify the validity of the results.

Tier I Estimated Environmental Concentrations for Use in the Human
Health Risk Assessment

For surface water, the acute (peak) value is 200 ppt and the annual
average value is 67 ppt.  The groundwater screening concentration is 6
ppt.  These values generally represent upper-bound estimates of the
concentrations that might be found in surface water and groundwater due
to the use of deltamethrin on broccoli, considering the possibility of
concurrent applications of tralomethrin, which appears to represent the
worst case scenario.  A separate memorandum addressing the estimated
Drinking Waters Concentrations summarizes the approach taken for the
calculation and more detailed results.

Summary of Laboratory Studies Reviewed by EFED

162-3/4  Aerobic/Anaerobic Metabolism of Deltamethrin (MRID# 44977005)

This study provides marginal supplemental information about the aquatic
metabolism of deltamethrin in an aerobic water and anaerobic sediment
system.  There were various deficiencies found in the system (as
described below).



The system was not completely aerobic nor anaerobic.  The study does not
fulfill data requirements 162-3 nor 162-4.  Although the water was kept
aerobic, the sediment was undisturbed and was anaerobic at the beginning
of the study.

The primary analytical method used for quantitation of compounds could
not separate parent deltamethrin from its α-R-isomer.

The material balance declined steadily throughout the study, and was
only an average 80-87% of the applied at the final sampling interval.

Radioactive material may have been adhered to the walls of the vessels,
steel supports, scintillation vials of the carbon dioxide traps, etc..

er content, and the other was a sandy loam with a much lower organic
matter content.  The pH in both systems was ≥8.0.  The waters and the
sediments were obtained from locations in the Neatherlands. 
Deltamethrin  was applied at the rate of 0.14 mg a.i./L water, and was
incubated for 84 days in darkness at 20°C.  Based on the data
available, results can be summarized as follows:

The following half-lives are based on total deltamethrin plus its
α-R-isomer

	Water-loam sediment from a ditch, Delft, Netherlands,

System I	Water-sandy loam sediment from Kromme Rijn river, Odijk,
Netherlands, System II

Half-life of water	6.0 days

(r2 = 0.806; 0-14 days)	<1 day

(observed)

Half-life in sediment	62.2 days

(r2 = 0.880; 2-84 days)	132 days

(r2 = 0.914; 1-84 days)

Half-life in entire system	25.9 days

(r2 = 0.902; 0-28 days)	120 days

α-R-isomer of deltamethrin =
[1R-[1-α-(R*),3-α-]]-3-(2,2-Dibromovinyl)-2,2-dimethyl-cyclopropanecar
boxylic acid, cyano (3-phenoxyphenyl)methyl ester,

volatile compounds, most likely CO2

Minor transformation prods.	3-PBA = 3-phenoxybenzoic acid

RU 53605 = [1R-[1-α-(S*),3-α-]]-3-(2,2-Dibromovinyl)-2,2
dimethyl-cyclopropanecarboxylic acid, cyano[3-(4-hydroxyphenoxy)
phenyl]-methyl ester



Aerobic conditions were maintained in the water layer of the
water-sediment systems throughout  the study; anaerobic conditions
existed in the sediment just prior to treatment and were not measured
thereafter.  Deltamethrin was initially associated to the water, and to
the sediment at later intervals.

formation product was α-R-isomer of deltamethrin (maximums of 21% at 7
days in loam sediment and 24% at 14 days in sandy loam sediment), water
layers were not analyzed for the α-R-isomer.

Unidentified volatilized [14C]residues (most likely CO2) were the major
transformation product totaling 26.5-31.2% of applied in water-loam
sediment systems and 19.7-21.8% in water-sandy loam sediment systems
after 84 days.

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cludes isomerization at the α-carbon to yield the α-R-isomer; ester
cleavage coupled with oxidation of the phenoxy moiety to yield
3-phenoxybenzoic acid; 4'-hydroxylation of the phenoxy moiety to yield
RU 53605 with subsequent ester cleavage to yield
4'-hydroxyphenoxybenzoic acid; ultimately, mineralization to volatile
compounds occurs.

163.1	Adsorption and Desorption of  14C-m-Phenoxybenzoic Acid in Four
Soils (MRID# 44977006)

This study provides partial information towards the fulfillment of the
mobility data requirement for deltamethrin.  The study provides
information about the mobility of a major degradate of deltamethrin,
m-phenoxybenzoic acid.  Some details of the study are not clear and the
registrant is required to submit additional information to clarify the
validity of the results. The missing parameters are described in the
following section and in the section of comments.

The adsorption/desorption characteristics of [benzylic
14C]m-phenoxybenzoic acid, was studied in clay soil [pH 7.6, organic
matter=0.4%], silty clay loam soil [pH 6.5, organic matter=1.4%], sandy
loam soil [pH 6.4, organic matter=4.40%], and clay loam soil [pH 6.8,
organic matter= 4.56%], each from the U.S. in a batch equilibrium
experiment.  The adsorption phase of the study was carried out by
equilibrating soil with [14C]m-phenoxybenzoic acid at nominal
concentrations of 0.25, 0.5, 2.5 and 5.0 mg a.i./kg at ambient
temperatures for 48 hours (actual temperatures and lighting conditions
not reported).  Based on the results obtained, the mobility of
m-phenoxybenzoic acid can be classified as moderate to very high.  A
summary of results is as follows:

Soil Adsorption and Desorption Characteristics for m-phenoxybenzoic acid

Soil	Adsorption	Desorption

	Kads	1/N	Koc	Mobility Classif.	Kdes	1/N	Koc

Clay	0.6677	0.9898	287.76	Moderate	0.8694	1.0280	374.73

Silty clay loam	1.5421	1.0068	189.90	Moderate	2.9957	1.1039	368.90

Sandy loam	2.6806	0.9386	105.03	High	4.2138	0.9570	165.10

Clay loam	1.3397	0.9218	50.65	Very high	1.8536	0.9331	70.08

Kads - Freundlich adsorption coefficients; 1/N - Slope of Freundlich
adsorption isotherms.

Koc - Coefficient adsorption per organic carbon (Kd or K x 100/% organic
carbon).

The mass balance at the end of adsorption phase of the study was not
reported.  The complete mean mass balance (adsorption and one desorption
phase) was 100.54%, 100.13%, 97.39%, and 101.53% of the applied for the
clay, silty clay loam, sandy loam and clay loam soils, respectively. 

 

 

