Document ID: EPA-HQ-OPP-2007-1107-0002
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-06-13T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF           

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

MEMORANDUM

	Date:	5 June 2007

	Subject:	Human Health Risk Assessment of the Section 18 Exemption for
Treatment of Grasses Grown for Seed with Fenoxaprop-p-ethyl.

		PP# 07OR14

		PC Code:  128701/129092

		DP Number:  338412

	From:	Michael A. Doherty, Ph.D., Chemist

		Registration Action Branch 2

		Health Effects Division 7509P

	Through:	Richard A. Loranger, Ph.D., Branch Senior Scientist

		Christina Swartz, Branch Chief

		Registration Action Branch 2

		Health Effects Division 7509P

	To:	Andrea Conrath/Dan Rosenblatt

		Risk Integration, Minor Use & Emergency Response Branch

		Registration Division 7505P

The state of Oregon has requested an emergency exemption for the use
fenoxaprop-p-ethyl to control weeds in ryegrass, and tall fescue grown
for seed.  This is the first assessment of this use (an identical
request in 2003 was withdrawn).  The exemption is for Puma® 1EC (EPA
Reg. No. 264-666), an emulsifieable concentrate formulation containing 1
lb of the active ingredient (a.i.) per gallon (11.53% a.i.).  Treatment
would be to Benton, Clackamas, Jackson, Lane, Linn, Marion, Polk,
Washington, and Yamhill counties in western Oregon at rates ranging from
0.05 to 0.0825 lb a.i. per acre.  Under the exemption, a maximum of
75,140 acres could be treated.  This represents 17% of the total acreage
used to produce annual ryegrass, perennial ryegrass, and tall fescue
grown for seed in the state.  The application season began 15 March 2007
and goes through 15 September 2007.  HED last completed a human health
risk assessment for fenoxaprop-p-ethyl in February 1998 (DP Barcode
D242374, S. Knizner, 2/3/98).  The Section 18 submission indicates that
Bayer CropScience plans to pursue a Section 3 registration of
fenoxaprop-p-ethyl on grasses grown for seed and will conduct magnitude
of the residue trials beginning autumn 2007.

Fenoxaprop-p-ethyl {[(+)-ethyl
2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid} provides
control of most annual and some perennial grass weed species.  The
herbicide has no activity against broadleaf species.  It belongs to the
aryloxyphenoxy propionate class of herbicides and is currently
registered for use on barley, cotton, peanut, rice, soybean, and wheat
commodities.  Tolerances [40 CFR 180.430] are established for combined
residues of fenoxaprop-ethyl, and its metabolites
2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid and
6-chloro-2,3-dihydrobenzoxazol-2-one in/on these commodities, as well as
livestock commodities.  Tolerances range from 0.02 ppm (milk) to 0.5 ppm
(wheat straw), with nearly all other tolerances being 0.05 ppm. 

For this Section 18 exemption, a single application of up to 0.0825 lb
a.i./A may be made.  Applications should be made at least 60 days prior
to harvest and grazing is likewise prohibited for at least 60 days after
application.  The application rate and PHI are approximately equivalent
to those listed on the label for barley and wheat.

HED is not conducting a new, quantitative risk assessment to evaluate
this Section 18 exemption.  Rather, this assessment is based on the
previous FQPA human health risk assessment cited above.  This approach
is being used for the following reasons:

Fenoxaprop is scheduled for registration review this year,

Bayer CropScience is actively pursuing a Section 3 registration for use
of fenoxaprop-p-ethyl on grasses grown for seed,

This Section 18 does not involve use on human foods,

This Section 18 is unlikely to alter the dietary burden for livestock.

HED believes that no changes to the conclusions of the 1998 assessment
need to be made as a result of this Section 18 exemption at this time. 
Risk conclusions from the 1998 assessment and supporting documents are
as follows:

  Acute Aggregate Exposure and Risk – From the acute dietary (food
only) risk assessment a high-end exposure estimate of 0.001 mg/kg/day
was calculated for females 13+ years.  This exposure yields a dietary
(food only) MOE of 32,000 for females 13+ years, (the population
subgroup of concern).  The potential contribution to acute exposure from
residues in drinking water is minimal (1000-fold less than HED level of
concern) and would not result in an aggregate acute exposure that
exceeds HED's level of concern 

  Short- and Intermediate-term Aggregate Exposure and Risk – As noted
above, fenoxaprop-ethyl is currently registered for use on turfgrass
including sod farms, commercial and residential turf and ornamentals. 
Also as indicated under Dose Response Assessment, no short- or
intermediate-term dermal toxicity endpoints have been identified for
fenoxaprop-ethyl.  An inhalation endpoint has been identified, however,
because of the nature of the residential uses (outdoors), exposure via
the inhalation route should be considerably less than that calculated
for worker mixer/loaders (MOE for aerial mixer/loader was 4,500, see
below).  Therefore, this route of exposure is not of concern.

Chronic Aggregate Exposure and Risk – For the US population, 0.4% of
the RfD is occupied by dietary (food) exposure.  As noted above,
potential chronic exposure from drinking water is at a level well below
HED's level of concern.  Because fenoxaprop-ethyl is currently
registered for use only on food/feed crops, no chronic residential
exposure is anticipated.

Aggregate Cancer Risk – The dietary (food only) cancer risk estimate
for the US population is 9.1 x 10-7.  The 56-day estimated environmental
concentrations provided by EFED using the GENEEC model were 0.56 ppt and
87 ppt for fenoxaprop-ethyl and fenoxaprop-acid, respectively (D. Spatz,
10/3/97).  According to the 11/20/97 SOP, the 56-day concentrations from
GENEEC can be divided by 3 prior to comparison with the chronic and
cancer drinking water levels of comparison (DWLOC’s).  Therefore,
dividing the combined levels of the parent and acid metabolite by 3, one
obtains about 29 ppt, which is less than the cancer DWLOC of 35 ppt.
Therefore, HED concludes that there is not a greater than negligible
cancer risk from chronic exposures to fenoxaprop-ethyl in drinking water
and food.

Occupational Risk – MOEs resulting from mixing/loading and application
of fenoxaprop-ethyl for use on barley range from 4,500 for aerial
mixer/loaders to 80,000 for aerial applicators.  These MOEs do not
exceed HED's level of concern for occupationally exposed workers. 
Cancer risk estimates for occupationally exposed workers also do not
exceed HED’s level of concern.

Given that the use patterns for the Section 18 exemption are nearly
identical to those for the use of fenoxaprop-p-ethyl on barley and
wheat, HED is translating residue data from that use to the use on
grasses grown for seed and recommends that time-limited tolerances be
established as follows:

	Grass, forage	0.05	ppm

	Grass, hay	0.05 ppm

Agency Memoranda Used to Support this Section 18 Exemption Risk
Assessment

PP#3F4182 FENOXAPROP-ETHYL on BARLEY. Evaluation of Nature of the
Residue, Analytical Method, and Magnitude of the Residue Data.

DP Barcode: D242374		Caswell#: 431C   

PRAT Case#:284224 			Chemical#: 128701  

40 CFR:  180.430			Class: Herbicide      

TO:		E. Wilson/J. Miller, PM Team 23

Herbicide Branch/RD (7505C)

FROM:	S. Knizner, E. Budd, M. Collantes. A. Levy

RAB2/HED (7509C)

DATE:		3 February 1998

[Note:  Despite the subject of the above memorandum, the document is a
risk assessment and not a chemistry chapter per se.]

PP#3F4182. Fenoxaprop-ethyl on Barley. Calculation of Drinking Water
Level of Concern.

Chemical# 128701 DP Barcode D244856 Caswell# 431C

FROM:	Richard Loranger, Ph.D., Chemist

Registration Action Branch 2

Health Effects Division (7509C)

THRU: 	Donna Davis, Branch Chief

Registration Action Branch 2

Health Effects Division (7509C)

TO: 		E. Wilson/J. Miller, PM Team 23

Herbicide Branch

Registration Division (7505C)

DATE:		2 April 1998

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