£% \ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
I ? WASHINGTON, D.C. 20460
^ wc
SI 2 MAY 1984
OFFICE OF
PREVENTION, PESTICIDES AND
DP Barcode: D182158, D186408, T°MtU|lW,ES
D170529, D170534, D165005, D175638,
D175632, D169871, D195745, D183233,
D164920
PC Code; 100601
MEMORANDUM;
Subject; Fenamiphos RED Chapter, Section 18, Registration Actions.
To;
From;
Lois Rossi, Branch Chief
Reregistration Branch
Special Review and Reregistration Division (7508W)
Everett Byington, Branch Chief
Science Analysis and Coordination Staff
Environmental Fate and Effects Division (7507C)
Henry Jacoby, Branch Chief
Environmental Fate and Ground Water Branch
Environmental Fate and Effects Division (7507
Based on EFGWB1s review and evaluation of available
environmental fate, ground and surface water data, fenamiphos
exceeds certain levels of concern for ground water and has
potential concerns for surface water. Because of these concerns, 1)
EFGWB recommended in 1992 that a prospective ground water
monitoring study be conducted for fenamiphos and its degradates
(the study is expected to begin in 1994 primarily to satisfy the
State of Florida requirements) , 2) EFGWB now recommends that
several other prospective ground water monitoring studies be
conducted, and 3) in addition, the registrant should be requested
to propose mitigation activities that will eliminate or reduce the
contamination of ground water by fenamiphos residues, and that
voluntary cancellation of this chemical in the United States be
considered if contamination continues. Because of potential
concerns for surface water source drinking water, it is recommended
that reregistration of fenamiphos be contingent upon the
registrants agreeing to fund monitoring programs for fenamiphos and
its sulfoxide and sulfone degradates in surface source water supply
systems which drain watersheds which typically receive high
fenamiphos applications.
Recycled/Recyclable
Q. Primed with Soy/Canola Ink on paper thai
V~1<~7 contains at least 50% recycled liDer
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i
% *
Although three guideline data requirements remain unfulfilled
at present, there are sufficient data'for comprehensive qualitaive
and quantitative environmental fate, ground and surface water
assessments for the emulsifiable concentrate (Nemacur 3EC).
However, additional field dissipation studies ate necessary using
granular formulations (Nemacur 15% G) to determine the dissipation
routes and half-life* the formation and decline of degradates, and
the potential for¦leaching, Fenamiphos dissipation in terrestrial
environments appears to be primarily by microbial metabolism
{aerobic soil metabolism half-life was 15.7 days,, anaerobic soil
metabolism half-life was 87.9 days) together with or followed by
leaching of degradates and further degradation. Laboratory data
indicates that fenamiphos is moderately resistant to degradation
when incorporated into the soil and has the potential to be highly
mobile (K^ ranging from 0.95 to 3.4) in different soils. The
degradates fenamiphos sulfoxide and fenamiphos sulfone appear to be
more mobile than parent fenamiphos. In upgradeable field
dissipation 'studies parent fenamiphos (Nemacur 3EC) was not
detected below the 0-6 inch soil horizon; however, fenamiphos
sulfoxide was detected as far as the 30-36 inch soil horizon and
fenamiphos sulfone was detected as far as the 18-24 inch soil
horizon.
The hydrolysis and anaerobic soil metabolism half-lives for
parent fenamiphos indicate that it will persist once it reaches
ground water. Thus fenamiphos use is likely to have a significant
impact on ground water quality. Leaching of fenamiphos was
confirmed by detections in ground water in Florida during a small
scale retospective monitoring study. Concentrations of parent
fenamiphos in ground water ranged up to 22.5 ppb, or approximately
1100 percent of the lifetime Health Advisory. The sulfoxide and
sulfone degradate concentrations ranged up to 204 ppb and 19.9 ppb
respectively. For this reason, the Agency required that the
registrant conduct a prospective ground-water monitoring study in
1992 and also requested a label advisory at that time.
Three guidelines are not fulfilled at this time: the unaged
portion of the leaching/adsorption/desorption (163-1), terrestrial
field dissipation (164-1), and prospective ground water monitoring
(166-1). Field dissipation studies using the granular formulations
(Nemacur 15% G), are necessary to determine the formation and
decline of degradates and the half-life, the dissipation routes,
and the potential for leaching under actual use conditions.
Prospective ground water monitoring studies are needed to establish
the extent of fenamiphos leaching into ground water and to identify
appropriate follow-up regulatory actions. Specific recommendations
are included in this RED package.
- 2 -
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t
Date Out: .1 2 MAi' 1334 Chemical Code:l00601
DP Barcode: D182158, D186408. D165691, D170529, D170534, D165005, D175638, D175632, D169871,
D195745, 0183233, D164920
ENVIRONMENTAL FATE AND GROUND WATER BRANCH
Review Action
To: Larry Schnaubett. PM # 72 Cynthia Giles-Parker, PM # 22
Special Review and Registration Division (7505C)
Rereglstratlon Division (7508W)
From; Henry Jacoby, Chief
Environmental Fate & Ground Water Branch
Environmental Fate and Effects Division (7507C)
Attached, please find the EFGWB review of..
Rebecca Cool, PM #41
Emergency Response Section
Registration Division (7505C)
Common Name:
Fenamlphos
Trade name:
Nemacur 3EC, Nemacur
15% G
Company Name:
Miles, Incorporated
ID'#:-;. '
100601, 94CA0002, 003125-00283, 003125-00236
Purpose:
Review environmental fate studies for reregistration; review applications for
amended registration; reissuance of a Section 18 in California; review status of
ground-water monitoring for Reregistration Eligibility Document.
|Type Product:
Action Code:
j Review Time: 1
| Insecticide/Nematicide
331, 606, 301, 305, 320, 330, 510
|40 days 1
STATUS OF STUDIES IN THIS PACKAGE: STATUS OF DATA REQUIREMENTS
ADDRESSED IN THIS PACKAGE:
Guideline#
MRtO
Status1
Guideline#
Status2
161-1
42149302
A
161-1
S~
161-3
40608001
A
161-3
S
162-1
421493
A
162-1
s
41064302,405
24601
C
162-2
s
162-2
4128SS01
A
163-1
p
163-1
40547502,
40547501
A
163-2
s
40774808,
40774807
U
163-2
40774810
A
164-1
42149301,
42216201
u
¦
164-1
N
Zstudy Status Codes:'" "A-Acceptable U'Upgradeabie C*Ancillary l«lnvalid
^Data Requirement Status Codes: S* Satisfied P = Partially satisfied N = Not satisfied R= Reserved W=Waived.
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1.0 CHEMICAL;
Common name: Fenamiphos
Chemical name: Ethyl 3-methyl-4-(methylthio)phenyl (1-methylethyl)
phosphoramidate
Trade Name: Kemacur
Chemical Structure:
2.0 TEST MATERIAL: See Individual DER's
3.0 STUDY/ACTION TYPE: Review of environmental fate and ground-
water data to support registration, new uses, section 18, and
reregistration.
4.0 STUDY IDENTIFICATION:
Mulford, D.J. 1987. Stability of NEMACUR in Sterile Aqueous Buffer
Solutions. Study performed and submitted by Mobay Corporation,
Kansas City, MO. MRID No. 421493-02.
Hanlon, C.M. 1988. Photodegradation of Fenamiphos on Soil. Study
performed and submitted by Mobay Corporation, Stilwell, Kansas.
MRID No. 406080-01.
Spiteller, M. 1989. Degradation of Fenamiphos, Nemacur in Aerobic
Sandy Loam. Study performed by Bayer Ag, Leverkusen-Bayerwerk, FRG.
Project No. M1250256-1. MRID No. 421493-03.
Simon, L., A. Haisch, and P. Wallnofer. 1988. Metabolism of
Fenamiphos in Soils of Different Geographic Origin under Aerobic
Conditions. Study performed by Bayer AG Institute of Metabolism
Research, FRG and submitted by Mobay Corporation, Stilwell, Kansas.
MRID No. 409337-01 (Duplicate MRID No. 410643-02).
Spiteller, M. 1989. Degradation of Fenamiphos, Nemacur, in
Anaerobic Sandy Loam. Study performed by Bayer AG, Institute for
Metabolism Research, Leverkuse,n-Bayerwerk, FRG for Mobay
Corporation, Stilwell, Kansas. MRID No. 412869-01.
ftnaaip&o*
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Hanna, G.R. 1980. The Metabolism of NEMACUR in Sandy Loam Soil.
Study performed and submitted by Mobay Corporation, stilwell,
Kansas. MRID No. 405246-01.
Mulford, D.J. 1987. Leaching Characteristics of Aged Soil Residues
of NEMACUR. Study performed and submitted by Mobay Corporation,
Stilwell, Kansas. MRID No. 405475-02.
Spiteller, M. 1987. Leaching Characteristics of Fenamiphos
(NEMACUR) Aged in Soil. Study performed by Bayer AG, Institute of
Metabolism Research, Federal Republic of Germany and submitted by
Mobay Corporation, Stilwell, Kansas. MRID No. 405475-01.
14
Daly, D. 1988. Soil Adsorption/Desorption with C-Nemacur
Sulfoxide. Study performed by Analytical Bio-Chemistry
Laboratories, Inc., Columbia, Missouri for Mobay Corporation,
Stilwell, Kansas. MRID No. 407748-07.
Daly, D. 1988. Soil Adsorption/Desorption with C-Nemacur. Study
performed by Analytical Bio-Chemistry Laboratories, Inc., Columbia,
Missouri. MRID No. 407748-08.
Detra, R.L. 1988. Volatility of Fenamiphos from the Surface of
Sandy Loam. Study performed and submitted by Mobay Corporation,
Stilwell, Kansas. MRID No. 407748-10.
Grace, T.J., K.S. Cain, and J.L, Delk. 1990. Dissipation of
Fenamiphos in California Soils. Study performed by Plant Sciences,
Inc., Watsonville, CA., Siemer and Associates, Inc., Fresno, CA.,
and Pharmacology and Toxicology Research Laboratory-East,
Lexington, Kentucky, for Mobay Corporation, Kansas City, Mo. MRID
No. 421493-01.
Appendix 1. Jacobsen, K.A., and S.K. Forrest. 1990.
Fenamiphos-(NEMACUR 3 EC) Field Dissipation for Terrestrial
Use Multiple Application Plot. Plant Sciences, Inc.,
Watsonville, CA.
Appenmdix 2. Hicks, S.C. 1990. NEMACUR 3 Turf Nemattcide-
California Soil Dissipation Study. Siemer & Associates, Inc.,
Fresno, CA.
Appendix 3. Moore, P., and J, Howard. 1990. Nemacur
(Fenamiphos) Soil Dissipation Study: Validation and Sample
Analyses of Soil. Study performed by PTRL East, Inc.,
Richmond, Kentucky, for Mobay Corporation, Stilwell, Kansas.
Carey, R. 1990. Subsurface Soil Incorporation Report, Mobay
Corporation, Fresno Site No.2. Study performed by Kleinfelder,
Inc., Fresno, CA., for Mobay Corporation, Kansas City, Missouri.
MRID No. 422162-01. (Report of analytical results of soil samples
from the Fresno location).
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5.0 REVIEWED BY:
George Tompkins
Entomologist, Review Section 1
EFGWB/EFED/OPP
Estella Waldman
Hydrologist, GWTS
EFGWB/EFED/OPP
6.0 APPROVED BY;
Paul Mastradone
Section Chief, Review Section 1
EFGWB/EFED/OPP
Elizabeth Behl
Section Chief, GWTS
EFGWB/EFED/OPP
Henry Nelson
Section Chief, SWS
EFGWB/EFED/OPP
Signature: Isw
Date! il 2 MAV 1934
Signature: Ct-jOA a- 7Y&J.oLr
Date: 5'/noM
'-J—
Signature:
Date:
Signature:
Date:
* X it f / \i
I I m
Signature:
Date: j/3/^
7.0 CONCLUSIONS:
Major Routes of Dissipation
Although the environmental fate data base is not complete, the
information from acceptable and upgradeable environmental fate data
from the 1987 Registration Standard to present indicate that the
major routes of dissipation for fenamiphos incorporated into the
soil appear to be by microbial metabolism (aerobic half-life was
15.7 days at 20 C; anaerobic half-life was 87.9 days at 20 C)
together with or followed by leaching of degradates and further
degradation. The Freundlich Kad values of fenamiphos ranged from
0.95 (sandy loam soil) to 3.4 (silt loam soil) indicating that
fenamiphos has the potential to be highly mobile to mobile in the
soils tested. The degradates fenamiphos sulfoxide and fenamiphos
sulfone appear to be more mobile than parent fenamiphos. In the
field studies (Nemacur 3 EC) fenamiphos was not detected below the
0-6 inch soil horizon. Fenamiphos sulfoxide was detected as far as
the 30-36 inch soil horizon in one study and fenamiphos sulfone was
detected as far as the 18-24 inch soil horizon in the same study
site. If fenamiphos were on the soil surface or in the water then
photolysis appears to be rapid (aqueous photolysis half-life was 2-
4 hours under artificial light; soil photolysis half-life = 2.7
hours under natural sunlight). Fenamiphos is relatively stable to
hydrolysis (half-life = 245 days at pH 5.0, 301 days at pH 7.0, and
235 days at pH 9.0).
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Laboratory and Field Half-lives
EFGWB concludes that the following studies submitted for the
reregistration of fenamiphos for Terrestrial Food Crop, Terrestrial
Food + Feed Crop, and Terrestrial Non-Food Crop uses are acceptable
and satisfy the data requirements.
a) Hydrolysis (161-1), MRID No. 42149302. Fenamiphos was stable to
hydrolysis with reported half-lives of 245 days at pH 5.0, 301 days
at pH 7.0, and 235 days at pH 9.0. The major degradate at all pH's
tested was fenamiphos sulfoxide, which by day 31 accounted for 9.9%
of the radioactivity in the pH 5.0 samples, 8.1% in the pH 7.0
samples, and 4.1% in the pH 9.0 samples. In the pH 9.0 samples
fenamiphos phenol was also found (5.2% of radioactivity by day 31).
b) Photodegradation on Soil (161-3), MRID No. 40608001. Fenamiphos
had a reported half-life of 2.7 hours when exposed to natural
sunlight. After 4 hr exposure, the major degradate was fenamiphos
sulfoxide (64.4% of applied radiocarbon) and 33.8% of the
radiocarbon was parent fenamiphos.
c) Aerobic Soil Metabolism (162-1), MRID No. 42149303 (two
additional ancillary studies were also submitted, MRID No.
41064302, and 40524601). Fenamiphos applied at a rate of 13.7 ppm
to a sandy Joam soil degraded with a reported half-life of 15.7
days at 20 C. The major metabolite was fenamiphos sulfoxide
(maximum of 51.4% of the applied radioactivity at day 14 and
decreased to 1.0% by day 365). Other identified degradates were
fenamiphos sulfone (maximum of 3.5% of applied radioactivity at day
14), fenamiphos phenol (<0.1% at all sampling intervals),
fenamiphos sulfoxide phenol (maximum of 5.4% at day 31), fenamiphos
sulfone phenol (maximum of 24.3% at day 63 and decreasing to 6.6%
by day 365), and fenamiphos sulfone anisole (steadily increased to
a maximum of 4.4% by day 365)^ By day 365 of the study 34.2% of the
applied was quantitated as C02. The proposed metabolic pathway
indicates that fenamiphos transformed to the corresponding
sulfoxide metabolite and further degraded to fenamiphos sulfoxide
phenol and fenamiphos sulfone phenol. C02 appeared to be produced
from the degradation of fenamiphos sulfoxide phenol and fenamiphos
sulfone phenol and possibly from the degradation of fenamiphos
phenol. In an ancillary study (MRID No. 40933701) it was
demonstrated that fenamiphos degraded more rapidly in the soil at
22 C than at 16 C in three temperate climatic zone soils, and also
more rapidly at 28 C than at 22 C in two tropic climatic zone soils.
d) Anaerobic Soil Metabolism (162-2), MRID No. 41286901, 40524601.
Fenamiphos degraded with a reported half-life of 87.9 days when
applied at a rate of 13.3 ppm to a sandy loam soil incubated at
20+1 C under anaerobic conditions after an initial 6 day aerobic
incubation period. The major degradate was fenamiphos sulfoxide
(maximum of 46.5% of applied radipactivity and decreasing to 14.3%
by day 66) . Other reported degradates were fenamiphos sulfone
- 4 -
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(maximum of 0.5% on days 46 and 60), fenamiphos phenol (maximum of
4.2+1.2% on day 52), fenamiphos sulfoxide phenol (maximum of 3.2%
on day 36), and fenamiphos sulfone phenol (maximum of 8.7% on day
66). Fenamiphos sulfone anisole was detected only on day 66 at
levels below 1% of applied radioactivity. In a second ancillary
study (MRID No. 40524601) the anaerobic half-life of fenamiphos
after 30 days aerobic incubation was reported at 280 days. The
major degradates reported were fenamiphos sulfoxide (55.6% of
applied radioactivity) and fenamiphos sulfone (5.4%). Other
reported degradates were fenamiphos sulfoxide phenol (2.1%) and
fenamiphos sulfone phenol (1.5%).
e) Laboratory Volatility (163-2), MRID No. 40774810. Fenamiphos did
not volatilize very rapidly when applied at a rate of 12 lbs ai/A
to a sandy loam soil. After 7 days, with a linear flow of air at 20
cm/min, less than 0.1% fenamiphos volatilized. This indicated that
volatilization was not a major route of dissipation for fenamiphos
when applied to soil.
f) Aged Leaching and Adsorption/Desorption (163-1), MRID No.
40547502, 40547501. Fenamiphos and its metabolites were mobile in
the Indiana sand soil in which 63.8% of applied radioactivity was
found in the leachate. Fenamiphos was somewhat less mobile in the
California sandy loam soil (47.2% of applied radioactivity found in
the leachate fraction) and in the Kansas sandy loam soil (16.2% of
the radioactivity found in the leachate fraction), The majority of
the radioactivity in the leachates was identified as fenamiphos
sulfoxide (86.4% of radioactivity in the leachate fraction from the
California sandy loam soil column was fenamiphos sulfoxide, 76.5%
from the Indiana sand soil leachate, and 90.12% in the leachate
from the Kansas sandy loam soil columns). The results indicated
that fenamiphos sulfoxide was the most highly mobile metabolite,
followed by fenamiphos sulfone. The majority of parent fenamiphos
did not leach through the columns (no parent fenamiphos found in
the leachate fractions of Kansas sandy loam soil).
EFGWB concludes that the following studies submitted for the
reregistration of fenamiphos are upgradeable and require further
information from the registrant (See 10.0-Discussion of Individual
Studies).
a) Unaged Leaching and Adsorption/Desorption (163-1), MRID No.
40774808, 40774807. In batch equilibrium studies using four
different soils unaged fenamiphos was shown to range from being
mobile in a sandy loam soil (Freundlich of 0.95) to moderately
mobile in a silt loam soil (K^ of 3.4). The K^ values ranged from
171.0 in the clay loam soil to 543.4 in the sand soil. These
results indicated that fenamiphos has the potential to be highly
mobile to mobile in the soils tested.
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b) Terrestrial Field Dissipation (164-1), MRID No. 42149301,
42216201. Fenamiphos (Nemacur 3) was surface sprayed onto
established turf plots at a rate of 10 lb ai/A to two sites located
at Chualar and Fresno, California. The reported half-life of
fenamiphos was 16.2 days in the sandy loam soil at Chualar and 17.0
days in a sandy loam soil at the Fresno site. Parent fenamiphos was
not detected (detection limits 0.01 ppm) below the 0-6 inch soil
horizon at either of the two sites at any sampling interval.
Fenamiphos sulfoxide was detected as far as the 24-30 inch soil
horizon at the Chualar site and as far as the 30-36 inch soil
horizon at the Fresno site. Fenamiphos sulfone was detected no
further than the 6-12 inch soil horizon at the Chualar site and
down to the 18-24 inch soil horizon at the Fresno site. The
cumulative rainfall/irrigation was 79.85 inches at the Chualar
location and 36.80 inches at the Fresno site.
At the Chualar site the maximum concentration of fenamiphos
was 0.211 ppm on day 0 of the first application and decreased
continually. The maximum concentration of fenamiphos sulfoxide was
0.983 ppm at 28 days posttreatment, and fenamiphos sulfone was also
a maximum (0.324 ppm) at this sampling interval. At the Fresno site
the maximum concentration of fenamiphos for the first application
was reported on day 0 (2.668 ppm). The maximum concentration of
fenamiphos sulfoxide was also on the day of application (1.394
ppm). The maximum concentration of fenamiphos sulfone was 60 days
posttreatment (0.521 ppm). It appears that fenamiphos dissipates by
microbial degradation to fenamiphos sulfoxide and fenamiphos
sulfone followed by leaching into the soil and eventual further
degradation as proposed in the aerobic soil metabolism study (MRID
No. 42149303, Appendix 18).
Additional Field Dissipation Studies using granular
formulations (Nemacur 15%G) are necessary to determine the
dissipation routes and half-life, the formation and decline of
degradates, and the potential for leaching.
Ground Water
As explained above, fenamiphos and its degradates, fenamiphos
sulfoxide and fenamiphos sulfone, are mobile and sufficiently
persistent to leach to ground water. Fenamiphos and its degradates
exhibit many of the properties and characteristics associated with
chemicals that have been detected in ground water. Fenamiphos is
mobile with Kd values that range from 0.95 to 3.4 L/kg in sandy
loam and silt loam soils. The degradates, fenamiphos sulfone and
fenamiphos sulfoxide, are more mobile than the parent compound. An
acceptable study indicated that the aerobic half-life for
fenamiphos was approximately 16 days; other information reports
half-lives up to 30 days for the parent. In addition, the
hydrolysis and anaerobic soil metabolism half-lives for parent
fenamiphos indicate that it will persist once it reaches ground
water. For these reasons, fenamiphos use is likely to have a
significant impact on ground-water quality.
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Leaching of fenamiphos was confirmed by detections in ground
water in Florida during a small-scale retrospective monitoring
study. Concentrations of parent fenamiphos in ground water ranged
up to 22.5 ppb or approximately 1100 percent of the lifetime Health
Advisory. The sulfoxide and sulfone degradate concentrations ranged
up to 204 ppb and 19.9 ppb respectively (DP Barcode D157194). For
this reason, the Agency required that the registrant conduct a
prospective ground-water monitoring study in 1992. The Agency also
requested a label advisory at that time.
Because fenamiphos and its degradates are both mobile and
persistent under certain conditions, they are likely to have an
impact on ground-water quality. In addition, over the long term,
persistent pesticides that have leached to ground water may be
discharged to surface-water bodies (i.e., streams, rivers, lakes,
wetlands). Therefore, contamination of ground-water resources may
also have an impact on ecological endpoints. Based on our current
knowledge about these endpoints, fenamiphos may have an impact on
aquatic invertebrates and fish through ground-water discharge. As
illustrated on graph in Appendix A, fenamiphos is not likely to
exceed some of the other risk-based levels of concern (LOCs) for
ecological effects.
Because certain LOCs for ground water have been exceeded,
EFGWB recommended that all fenamiphos labels contain a ground-water
advisory, in 1992, EFGWB recommended that a prospective ground-
water monitoring study be conducted for fenamiphos and its
degradates. The study is expected to begin sometime in 1994,
primarily to satisfy the State of Florida requirements. In light of
the acetochlor decision, EFGWB now recommends that several other
prospective ground-water monitoring studies be conducted for
fenamiphos. In addition, the registrant should be requested to
propose mitigation activities that will eliminate or reduce the
contamination of ground water by fenamiphos residues, and that
voluntary cancellation of this chemical in the United States be
considered if contamination continues.
Fenamiphos Surface Water Advisory
Under some conditions fenamiphos and its sulfoxide and sulfone
degradates may have a high potential for runoff into surface water
(primarily via dissolution in runoff water), for several weeks to
months post-application. These include poorly draining or wet soils
with readily visible slopes, frequently flooded areas, areas
experiencing immediate post-application runoff events before
fenamiphos can be soil incorporated, areas over-laying extremely
shallow ground water, and areas over-laying tile drainage systems
that flow to surface water.
- 7 -
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Surface Water Source Drinking Water Concerns
Fenamiphos is of potential concern to surface source drinking
water because of its relatively low soil/water partition
coefficient and relatively low lifetime health advisory of 2 ug/L
which may become its MCL. It also has relatively low acute 1-10 day
health advisories of 9 ug/L- Although fenamiphos is normally
incorporated, it remains a potential threat to surface water due to
frequently high application rates, and to tile drainage.
The Surface Water Section has not seen any data on the
concentrations of fenamiphos in surface water. Since fenamiphos is
not currently regulated under the Safe Drinking Water Act (SDWA),
water supply systems are not required to sample and analyze for it.
Because of potential concerns for surface water source
drinking water, it is recommended that reregistration of fenamiphos
be contingent upon the registrants agreeing to fund monitoring
programs for fenamiphos and its sulfoxide and sulfone degradates in
surface source water supply systems which drain watersheds which
typically receive high fenamiphos applications. The numbers and
locations of the systems for which monitoring would be funded can
be negotiated as well as the duration of the monitoring programs.
Based upon major fenamiphos uses, crop distribution maps, and
areas of no to limited irrigation, potential areas of interest for
monitoring surface water might include turf drainage systems in any
part of the country which flow to surface water? the Mississippi
River Basin in AR, TN, MS, and LA (cotton) ; Southeast AL, Southwest
GA, Southeast VA, Northeast NC (peanuts) ,* Florida (citrus), KY, NC,
and Southern MD (tobacco); Southwest NY (grapes); Western MI,
Western NY, Southeastern NY, and 4 state intersection area of VA,
WV, MD, and South Central PA (apples); Central GA, sc, South
Central PA (peaches); and HI (pineapples).
If the results of the monitoring program indicate that
fenamiphos exceeds drinking water health advisories, the following
is recommended:
Surface Water Scenario I:
If one (1) community water supply system, that derives
its water primarily from surface water, detects an annual
time-weighted mean concentration of >2 ppb, or confirmed peak
concentration >9 ppb fenamiphos, then either;
The use of fenamiphos in the related watershed will be
prohibited. Such prohibition will be implemented by means of
amendment of the fenamiphos registration to prohibit sale,
distribution, and use in the specified watershed. The timing,
content, and implementation of such restriction shall be
governed EPA and the registrant.
The registrant will adsorb 100% of costs required to restore
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the community water supply system to compliance. If EPA
determines that the registrant has failed to meet this
obligation, it may cancel the registration without opportunity
for hearing.
»
Surface Water Scenario II:
If EPA determines two (2) large (serving 100,000 people)
community water supply systems, or ten (10) community water
supply systems of any size across wide use areas have an
annual time-weighted mean concentration of >2 ppb, or
confirmed peak concentrations >9 ppb, or are otherwise
determined to be out of compliance based on Office of Water
criteria, the registration will be automatically canceled.
7.1 STATUS OF DATA REQUIREMENTS:
Data requirements
Review Status MRID #
161-1
161-2
161-3
161-4
162-1
162-2
163-1
163-2
164-1
165-4
42149302
00079270,
00133402
40608001
EAB # 80118 (2Aug88)
42149303
41286901
Hydrolysis Satisfied
Photolysis—Water Satisfied
Photolysis—Soil Satisfied
Photolysis—Air Waived
Aerobic Soil Metabolism Satisfied
Anaerobic Soil Metab. Satisfied
Leaching and Ads./Des. Partially satisfied
Aged portion satisfied—40547502
Unaged portion upgradeable—40774808
Laboratory volatility Satisfied 40774810
Terrestrial Field Diss. (EC) Upgradeable 42149301, 42216201
Granular (15% G)
Unsatisfied
Fish Bioaccumulation Satisfied 40274201, 40274202,
40274203
166-1 Prospective GW Monitoring Unsatisfied
201-1 Droplet Size Spectrum Waived EAB # 80118 (2Aug88)
202-1 Field Spray Drift Evaluation Waived EAB # 80118 (2Aug88)
1. This study was waived because its method of application results
in low exposure of fenamiphos to sunlight.
2. Based on the method of application (applied by ground spray (EC)
or granule to soil surface and immediately soil incorporated)
fenamiphos is not expected to present an appreciable exposure to
humans and other non-target organisms by spray drift or runoff.
However, if the label is amended in the future to include other
methods of application, spray drift, runoff, and/or surface
water monitoring data may be requested.
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ENVIRONMENTAL FATE SUMMARY:
Based on acceptable hydrolysis data fenamiphos appears to be
relatively stable to hydrolysis in buffer solutions with reported
half-lives of 245 days at pH 5.0, 301 days at pH 7.0, and 235 days
at pH 9.0. The major degradate reported was fenamiphos sulfoxide
which by day 31 of the study accounted for 9.9% of the
radioactivity in the pH 5.0 samples, 8.1% in the pH 7.0 samples,
and 4.1% in the pH 9.0 samples. Fenamiphos phenol was found in the
pH 9.0 samples (5.2% of the total radioactivity by day 31).
Based on acceptable aqueous photolysis data submitted
previously the aqueous photolysis half-life was 2-4 hours at pH 7.0
when exposed to artificial (450 watt mercury arc lamp emitting
light of "5200 uW/cm intensity at the sample surface) between 300-
600 nm. After 24 hours of irradiation fenamiphos accounted for "4%
of the applied radioactivity and the major degradates reported were
fenamiphos sulfonic acid phenol ("19%), fenamiphos sulfoxide
("17%), and fenamiphos sulfonic acid (~6%). Based on acceptable
soil photolysis data the half-life of fenamiphos was 2.7 hours when
exposed natural sunlight. The radioactive components identified
from the treated exposed soil samples were fenamiphos sulfoxide and
parent fenamiphos.
Based on acceptable aerobic soil metabolism data fenamiphos
applied at a rate of 13.7 ppm to Howe sandy loam soil degraded
rapidly (half-life - 15.7 days) to form fenamiphos sulfoxide
(maximum of 51.4% by day 14), fenamiphos sulfone (maximum of 3.5%
at day 14), fenamiphos phenol (<0.1% at all sampling times),
fenamiphos sulfoxide phenol (maximum of 5.4% on day 31), fenamiphos
sulfone phenol (maximum of 24.3% on day 63) , and fenamiphos sulfone
anisole (maximum of 4.4% on day 365). By the end gf the study 34.2%
of the applied radioactivity was quantitated as C02. The proposed
metabolic pathway indicated that fenamiphos transformed to the
corresponding sulfoxide metabolite and further degraded to
fenamiphos sulfoxide phenol and fenamiphos sulfone phenol.
C02 appeared to be produced from the degradation of fenamiphos
sulfoxide phenol, fenamiphos sulfone phenol and possibly from the
degradation of fenamiphos phenol. An additional ancillary-study
indicated that fenamiphos degraded in the soil more rapidly at 22 C
than at 16 C and also more rapidly at 28 C than at 22 C.
Based on acceptable anaerobic soil metabolism data fenamiphos,
applied at a rate of 13,3 ppm to a Howe sandy loam soil, degraded
with a half-life of 87.9 days. In this study fenamiphos was
incubated for 6 days under aerobic conditions followed by 60 days
incubation under anaerobic conditions. Fenamiphos declined from
36.3% on day 0 of anaerobic incubation (following the 6 day aerobic
incubation) to 21.8 + 1.9% after 60 days anaerobic incubation. The
major metabolite was fenamiphos sulfoxide (maximum of 46.5% at day
6 of aerobic conditions and decreasing to 14.3% after 60 days
anaerobic incubation). Other reported metabolites were fenamiphos
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sulfone (maximum of 0.5% on days 52 and 66), fenamiphos phenol
(maximum of 3.2% on day 36), fenamiphos sulfone phenol (maximum of
8.7% on day 66), and fenamiphos sulfone anisole (<1% on day 66).
Based on upgradeable batch equilibrium data the reported
Freundlich values from four unclassified soils ranged from 0.95
in a sandy loam soil to 3.4 in a silt loam soil. The values
ranged from 165.6 to 543.4. These values indicate that parent
fenamiphos has the potential to be relatively mobile in the soils
tested.
Four mobility and adsorption/desorption studies were
submitted. Two (MRID No. 40547501 and 40547502) had been previously
reviewed. Based on acceptable column leaching studies, parent
fenamiphos was mobile (16.2% to 63.8% of applied radioactivity was
found in the leachate) . The major metabolites, fenamiphos sulfoxide
and fenamiphos sulfone were more mobile. The greatest mobility of
fenamiphos and its metabolites was in the soil with the lowest
cation exchange capacity and the lowest percentage of organic
matter (Indiana sand soil) and vice versa (Kansas sandy loam soil).
No parent fenamiphos was found in the leachate from the Kansas
sandy loam soil. The leachate from the soil columns contained 47.2%
of applied radioactivity in the California sandy loam soil, 63.8%
in the Indiana sand soil, and 16.2% in the Kansas sandy loam soil.
Of this radioactivity found in the leachates the majority was
fenamiphos sulfoxide (86.44% of radioactivity in leachate from the
California sandy loam soil, 76.48% of radioactivity in leachate
from the Indiana and soil and 90.12% of radioactivity in the
leachate from the Kansas sandy loam soil). These results indicated
that fenamiphos sulfoxide was the most mobile metabolite, followed
by fenamiphos sulfone, and the majority of parent fenamiphos did
not leach through the soil columns.
Based on acceptable laboratory volatilization data fenamiphos
did not volatilize very rapidly when applied at a rate of 12 lb
ai/A to a sandy loam soil. After 7 days less than 0.1% fenamiphos
volatilized indicating that volatilization was not a major route of
dissipation for fenamiphos applied to the soil.
Based on upgradeable terrestrial field dissipation studies
conducted in Chualar and Fresno, California on established turf
plots previously used for crop production, parent fenamiphos
(Nemacur 3 EC) applied at 10 lb ai/A was not very mobile. The half-
life of fenamiphos was 16.2 days at the Chualar site and 17 days at
the Fresno site. Parent fenamiphos was not detected (detection
limits 0.01 ppm) below the 0-6 inch soil horizon at either of the
two sites. Fenamiphos sulfone was detected as far as the 6-12 inch
soil horizon at the Chualar site and as far as the 18-24 inch soil
horizon at the Fresno site. Fenamiphos sulfoxide was detected as
far as the 24-30 inch soil horizon at the Chualar site and as far
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as the 30-36 inch soil horizon at the Fresno site. These studies
confirmed the results of the laboratory leaching and
adsorption/desorption studies demonstrating that the metabolites
fenamiphos sulfoxide and fenamiphos sulfone are both more mobile
than the parent and have a greater potential to leach in the soil.
It appears that fenamiphos dissipates in the soil by microbial
degradation to fenamiphos sulfoxide and fenamiphos sulfone followed
by leaching into the soil and eventual further degradation as
proposed in the aerobic soil metabolism study.
At the Chualar site the concentration reported for total
fenamiphos residues at day 0 of the first application at a rate of
10 lb ai/A was 0.32 ppm (parent fenamiphos accounted for 0.21 ppm).
The maximum concentration reported at this site for fenamiphos
sulfoxide was 0.98 ppm at day 28 posttreatment and the maximum
fenamiphos sulfone concentration was 0.32 also at day 28. At the
Fresno site the total residue concentration at day 0 was 4.06 ppm
(parent fenamiphos was 2.668 ppm and fenamiphos sulfoxide was 1.39
ppm) and this was when the maximum concentration of parent
fenamiphos and fenamiphos sulfoxide were reported. The maximum
concentration of fenamiphos sulfone was 0.52 ppm at day 60
posttreatment. No information from acceptable field dissipation
studies using granular (Nemacur 15% G) formulations is currehtly
available.
Leaching of fenamiphos was confirmed by detections in ground
water in Florida during a small-scale retrospective monitoring
study. Concentrations of parent fenamiphos in ground water ranged
up to 22.5 ppb or approximately 1100 percent of the lifetime Health
Advisory. The sulfoxide and sulfone degradate concentrations ranged
up to 204 ppb and 19.9 ppb respectively (DP Barcode D157194). For
this reason, the Agency required that the registrant conduct a
prospective ground-water monitoring study in 1992. The Agency also
requested a label advisory at that time.
Based on an acceptable fish bioaccumulation study, the maximum
bioaccumulation factors (BCF) for fenamiphos residues were 89X for
whole fish at 14 days exposure, 24X for fillet tissue at 7 days
exposure, and 23OX for viscera at 7 days exposure. The average
steady state BCF was 86X during the course of the study. After 28
days the BCFs were 21X, 61X, and 98X for fillet, whole fish, and
viscera, respectively. During the 14 day depuration period,
accumulated C-fenamiphos residues dropped >95% to 98% of the
observed concentration at day 28 of uptake exposure in the fillet,
whoe fish and viscera, respectively. The phenol sulfone metabolite
was the primary metabolite found in the tissue and accounted for
42.7% and 51.0% of the radioactivity in the 21 and 28 day viscera
tissues. Parent fenamiphos, the sulfoxide, sulfone, phenol, and
phenol sulfoxide metabolites were found in amounts less than 10%.
These results indicated that fenamiphos did not bioaccumulate in
fish and any residues taken up by fish were depurated when fish
were no longer exposed to these residues.
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Registration Actions
7.2 (DP Barcode D195745) The State of California, Department of
Pesticide Regulation has requested the reissuance of a Section 18
Specific Exemption for the use of fenamiphos (Nemacur 3
Emulsifiable Nematicide, EPA Reg. No. 3125-283-AA) on broccoli and
cauliflower. The request specifies that approximately 95* of
127,980 acres of broccoli and 48,719 acres of cauliflower will
require treatment. Fenamiphos is to be applied as a banded
application at a rate equivalent to a maximum of 6 lbs fenamiphos
per broadcast acre once per season at planting or transplant and is
to be incorporated into the soil by mechanical equipment or by low
volume irrigation (drip type system with the lines at least 2
inches below the soils surface). Although the environmental fate
data base for fenamiphos is not complete, sufficient information is
currently available to establish the dissipation of the
emulsifiable formulation of fenamiphos (Nemacur 3 EC) beneath the
soil surface. Fenamiphos appears to degrade rapidly by photolysis
and aerial and broadcast applications of this product are
prohibited under the emergency exemption. Because fenamiphos and
its degradates are both mobile and persistent under certain
conditions, they are likely to have an impact on ground-water
quality.
7.3 (DP Barcode 169871) Mobay Corporation has submitted a petition
proposing amendment of 40 CFR 180.349 by establishing tolerances
for residues of Nemacur and its cholinesterase inhibiting
metabolites in or on the raw agricultural commodities almonds,
almond hulls, pecans, plums and walnuts. This action pertains to
HED.
7.4 (DP Barcode 165005, 164920) Mobay Corporation has requested a
change in the labelling to propose use of Nemacur 3 and Nemacur 15%
Granular for control of nematodes and banana root borer infesting
bananas and plantains grown in Puerto Rico and bananas in Hawaii.
For bananas in Hawaii the application states that not more than 3.5
gallons (10 lb ai) are to be applied per acre per year for Nemacur
3IC or not more than 66 lbs of Nemacur 15% G (10 lb ai/A) per
acre per year. However, the label for both Nemacur 3 EC or Nemacur
15% G in Puerto Rico does not specifically state the maximum amount
of active ingredient that may be applied. It states that for the EC
formulation that not more than 25 ml per production unit per year
are to be applied and that for the 15% G formulation that not more
than 60 grams per production unit per year are to be applied. The
label needs to be modified to reflect the maximum application of
active ingredient per acre. A tolerance of 0.10 ppm has been
established for the combined residues of fenamiphos and its
cholinesterase inhibiting metabolites in/on bananas. Additional
Field Dissipation Studies are necessary to determine the
dissipation of granular formulations (Nemacur 15% G) of fenamiphos.
EFGWB is concerned that the use of fenamiphos in these locations
may result in contamination of ground water because of the soil
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types prevalent in these areas.
7.5 (DP Barcode D175638, D175632) . This action is in response to DP
Barcode D155171 (EFGWB # 90-0843) for use of Nemacur 3 EC and
Nemacur 15% G on broccoli and cauliflower. Mobay has addressed the
concern for lack of data requirements. In addition a revised label
was submitted which addressed the maximum use rate (3 lb ai/A) per
field acre was specified as well as the application rate (2.0 to
9.8 fluid ounces per 1000 ft of row for any row spacing for the
Nemacur 3 EC formulation and 20 lb of the Nemacur 15% G
formulation). Mixing instructions were also included on the label.
It is to be noted that additional field dissipation studies are
necessary to determine the dissipation of granular formulations of
fenamiphos.
7.6 (DP Barcode D170529, D170534) Nemacur 15% G is currently
registered as a single application prior to transplanting for
control of nematodes infesting brussels sprouts. A tolerance of 0.1
ppm has been established to cover residues of fenamiphos and its
sulfone and sulfoxide metabolites in or on the raw agricultural
commodity brussels sprouts. The enclosed draft labeling is seeking
to expand the current Nemacur 15% G label on brussels sprouts by
adding directions for multiple applications. No information was
provided on the maximum use of active ingredient per acre per
season on the label. A second request (D170534) seeks to add the
use of Nemacur 3 EC for use of a single (prior to transplanting)
and multiple applications (prior to transplanting plus additional
applications after planting) for control of nematodes infesting
brussels sprouts. This label does not contain information
specifying the maximum application of active ingredient per season
and should contain this information. Additional field dissipation
studies are necessary to determine the dissipation of granular
formulations of fenamiphos.
7.7 (DP Barcode D165691) Resubmission of proposed labeling for
potatoes, sweet potatoes (to include yams), sugarbeets and tomatoes
for both Nemacur 3 EC and Nemacur 15% G. For each crop the label
directions were not very clear and did not specify the maximum
application rate per season (ai/A). The maximum use rate in the
LUIS Report is 20 lb ai/A per season. In the submitted label for
the 15% G, the row spacing and equivalent dosage for the row
spacing should be listed. It presently lists 22 oz for any row
spacing for potatoes (20 lb ai/A for 36 inch rows) but does not
list 20 lb ai/A per season as the maximum. If the rows were spaced
closer and the application rate were the same then the dosage per
acre would exceed this application rate.
The label submitted for the proposed use of Nemacur 3 EC and
Nemacur 15% G on carrots did not list the maximum application per
season (ai/A). The difference between application of the
formulation and active ingredient' per acre in the labels was not
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delineated and must be made clear. Additional field dissipation
studies with Granular formulations are still necessary to determine
the the dissipation of these formulations.
8.0 RECOMMENDATIONS:
The environmental fate data base is not complete. The unaged
leaching and adsorption/desorption (163-1) portion of the study is
upgradeable. The field dissipation studies using the emulsifiable
concentrate formulation of fenamiphos (Nemacur 3 EC) are
upgradeable. However, additional field dissipation studies using
granular formulations (Nemacur 15% G) are necessary to determine
the dissipation of fenamiphos when applied in this type of
formulation. Previous unacceptable field dissipation studies using
granular formulations (MRID Nos. 00118796-A and B with 10% G
formulations and 00118796-F, G, and I with 15% G formulations) did
not use specific analytical methods to identify parent and
degradates, did not address the formation and decline of
degradates, and soil samples were taken only from 0-6 inches and
could not define the extent of leaching.
EFGWB recommends that several additional prospective ground-
water monitoring studies be conducted for fenamiphos. The locations
for these studies will depend on the use areas.
EFGWB recommends that the registrant should be requested to
propose mitigation activities that will eliminate or reduce
the contamination of ground water by fenamiphos residues. If
contamination of ground water continues, the registrant should
consider voluntary cancellation of this chemical in the United
States.
9.0 BACKGROUND:
The LUIS Report (12/1/93) indicates that fenamiphos is an
insecticide and nematicide registered for a variety of terrestrial
food crop, terrestrial food + feed crop, and terrestrial non-food
crop use sites. These include apples, asparagus, bananas
(plantains), beets, bok choy, brussels sprouts, cabbage, cherries,
citrus fruits, cotton, eggplant, garlic, grapes, kiwi fruits,
nectarines, okra, peaches, peanuts, peppers, pineapples,
raspberries, strawberries, and tobacco. Other uses also include
application to ornamental herbaceous plants, ornamental lawns and
turf, and golf course turf. All formulations are restricted use.
The chemical is applied to the soil by broadcast spray, soil
injection, chemigation, ground spray, soil band treatment, or soil
in furrow treatment. Unless otherwise specified, product must be
incorporated into the soil for optimum results. Incorporation may
be accomplished by irrigation or mechanical equipment. Application
rates range from 0.5 to 20 lb ai^A. Multiple applications may be
made during the growing season. Tolerances for residues of
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fenamiphos in/on raw and in processed plant commodities are
currently expressed in terms of the combined residues of fenamiphos
and its cholinesterase-inhibiting metabolites, fenamiphos sulfoxide
and fenamiphos sulfone. These tolerances currently are set at 0.02-
0.60 ppm.
10.0 DISCUSSION OF INDIVIDUAL STUDIES:
10.1 Unaged leaching and adsorption/desorption batch equilibrium
study, MRID No. 407748-08. In this study the origin and
classification of the four soils used in the study was not
provided. This study did provide information on the potential
mobility of parent fenamiphos in four different soils.
10.2 Terrestrial Field Dissipation study, MRID No. 42149301, EC
formulations. In this study it is requested that an explanation of
the poor initial (day 0) recovery of parent and continual low
material balance from the Chualar site be explained. The recovery
of total fenamiphos residues on day 0 at the Fresno site was
significantly greater. However, an explantion for the high recovery
of fenamiphos sulfoxide at day 0 (the maximum concentration of
fenamiphos sulfoxide and of parent fenamiphos was on the day of
application) at this site is requested. No explanation was provided
as to how the turf in the soil cores was handled or extracted at
either of the two sites.
Additional field dissipation studies using granular
formulations (Nemacur 15% G) are necessary to determine the
dissipation of fenamiphos, the pattern of formation and decline of
degradates, and the potential for leaching for this type of
formulation. Previous unacceptable studies using granular
formulations (MRID Nos. 00118796-A and B using a 10% G formulation
and 00118796-F, G and I using a 15% G formulation) were all
unsatisfactory because the analytical methods were non specific,
the formation and decline of degradates was not addressed, and the
soil was not sampled deep enough (only 6-inch soil samples taken)
to define the extent of leaching.
Registration Actions
10.3 DP Barcode D195745, ID# 94CA0002. The State of California has
requested the reissuance of a Section 18 Specific Exemption Nemacur
3 Emulsifiable Nematicide (EPA Reg. No. 3125-283-AA) for broccoli
and cauliflower for cyst nematodes (sugarbeet cyst nematode-
Heterodera schachtii: cabbage cyst nematode- Heterodera
cruciferae). This request specifies that the main counties where
broccoli are grown are Monteray, San Benito, Fresno, Kings, San
Luis Obispo, Santa Barbara, Ventura, Riverside and Imperial and
that an estimated 127,980 acres of broccoli will be planted. The
main counties where cauliflower are grown are Monteray, San Luis
Obispo, Santa Barbara, Santa Cruz, Imperial, Riverside, San Diego
and Stanislaus and that an estimated 48,719 acres of cauliflower
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will be planted. In both cases it was estimated that 95% of the
acreage will require treatment. However, the total acreage listed
that will require treatment was 176,699 acres (100%).
The total amount of fenamiphos to be applied was not
specified. The alternate control measures listed were: 1) Telone-
the use of Telone products in California has been suspended; 2)
Vapam- provided inconsistent nematode control; high rates of 75-100
gallons per acre for field application; cost prohibitive;
application equipment and material problems; treatment problems and
extended waiting periods after application; 3) Methyl Bromide- high
volumes for field application; application problems and waiting
periods prior to planting; weather sensitivity, buffer zones, and
rotation restrictions all listed as adverse problems. Technical
experts project broccoli and cauliflower yield losses to be 20-80%
without the use of the proposed material.
An attachment included the use directions. In this attachment
the dosage specifies that banded application at a rate equivalent
to a maximum of 6 lbs fenamiphos per broadcast acre. The frequency
of application is to be once per season at planting or transplant.
At present the current data in EFGWB files is incomplete but
sufficient information is available to establish the mode of
dissipation of fenamiphos in soil when applied as an emulsifiable
concentrate. Fenamiphos is acutely toxic to mammals, birds and
fish. The State of California Fish and Wildlife staff has concluded
that "although fenamiphos is highly toxic to fish and wildlife,
soil incorporation should preclude significant exposures. Use on
broccoli and cauliflower should not pose a threat to fish and
wildlife generally or endangered species in particular due to low
probability of exposure." Because fenamiphos and its degradates are
both mobile and persistent under certain conditions, they are
likely to have an impact on ground-water quality.
10.4 DP Barcode 169871. Mobay has petitioned for establishing
tolerances for residues of fenamiphos and its cholinesterase
inhibiting metabolites in or on the raw agricultural commodities
almonds at 0.3 ppm, almond hulls at 0.4 ppm, pecans at 3.5 ppm,
plums at 0.02 ppm, and walnuts at 0.4 ppm, and a food additive
tolerance on prunes at 0.04 ppm. It is specified that Nemacur 3 EC
should be applied at the rate of 1.5 gallons (72 02 ai/A) per acre
in a 50% band or at 2 quarts (0.5 gallon) to 1.5 gallons (24 to 72
02 ai/A) per acre by low pressure irrigation. The maximum amount of
Nemacur which can be applied is 3 gallons (9 lb ai/A) per acre per
year. These rates do not exceed the rates used for laboratory or
field studies.
10.5 DP Barcode 165005, 164920. Mobay has requested a change in the
labeling to include the use of both Nemacur 3 EC and Nemacur 15% G
for control of nematodes and banana root borer infesting bananas
and plantains grown in Puerto Rico and bananas grown in Hawaii. The
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maximum application of active ingredient per acre for use in Hawaii
was specified on the label (10 lb ai/A). However, the labeling was
not specific as to the maximum application rate for use of either
formulation in Puerto Rico (for the EC it stated that not more than
25 ml per production unit per year are to be applied and for the
15% 6 formulation that not more than 60 grams per production unit
per year are to be applied). EFGWB is concerned that the use of
fenamiphos in "these locations may -result in contamination of ground
water' because of the soil types prevalent in' these areas.
Additional field dissipation studies with granular formulations are
necessary to satisfy this environmental fate data (164-1)
requirement.
10.6 DP Barcode D175638, D175632. This response was to previous
request (DP Barcode D155171, EFGWB # 90-0843) for use of Nemacur 3
EC and Nemacur 15% G on broccoli and cauliflower. At that time only
the data requirements for hydrolysis, photodegradation in water and
the aged portion of the leaching and adsorption/desorption studies
had been satisfied. In this response a revised label was submitted
addressing the maximum use rate (2.0 to 9.8 fluid oz per 1000 ft of
row for any row spacing for the Nemacur 3 EC formulation and 20 lb
of the Nemacur 15% G formulation). Adequate mixing instructions
were also included. Additional field dissipation studies are
required to determine the dissipation of granular formulations of
fenamiphos.
10.7 DP Barcode 170529, 170534. Nemacur 15% G is currently
registered, as a single application prior to transplanting for
control of nematodes infesting brussels sprouts. A tolerance of 0.1
ppm has been established to cover residues of fenamiphos and its
sulfone and sulfoxide metabolites in or on the raw agricultural
commodity brussels sprouts. One enclosed draft labeling (DP Barcode
170529) is seeking to expand the current Nemacur 15% G label on
brussels sprouts by adding directions for use of a single (prior to
transplanting) and multiple applications (prior to transplanting
plus two additional 6-inch band or side-dress applications on each
side of the row at 30 and 60 days after planting) for control of
nematodes infesting brussels sprouts. A second draft labeling (DP
Barcode 170534) is seeking to expand the current Nemacur 3 EC
lanbel by adding directions for use of a single (prior to
transplanting) and multiple (prior to transplanting plus two
additional 6-inch band or side-dress applications on each side of
the row at 30 and 60 days after planting) applications for control
of nematodes infesting brussels sprouts. Residue data submitted in
Mobay Report No. 99712 indicated that the proposed multiple
application use pattern will not result in residues of fenamiphos
and its sulfoxide and sulfone metabolites over the currently
established tolerance of 0.1 ppm. In both draft labeling requests
information specifying the maximum application of active ingredient
was not included.
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10.8 DP Barcode D165691. Mobay has resubmitted a proposed labeling
for potatoes, sweet potatoes (to include yams), sugarbeets, and
tomatoes for both Nemacur 3 EC and Nemacur 15% G. The label
directions were not very clear as to the dosage applied or to the
maximum application per season. The distinction between ounces of
applied material or of active ingredient was not made. For the
crops the minimum row spacing and.its application per season was
not clear, i.e.-potatoes (20 lb/A on 36-inch rows) and no mention
made as to if this is the minimum spacing and maximum application
rate of active ingredient/A/season. Labeling did not distinguish
between dosage of formulated material or of active ingredient per
1000 ft of row.
In the proposed new use on carrots for both Nemacur 3 EC and
Nemacur 15% G there was no specification of the maximum application
per season.
11.0 COMPLETION OF ONE-LINER: updated 10 March 1994
12.0 CBI APPENDIX; None
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APPENDIX A
GROUND WATER ASSESSMENT
FENAMIPHOS RED
Background
In 1989, the State of Florida requested that Miles, Inc. (then
Mobay) conduct a small-scale retrospective ground-water study for
the registration of fenamiphos on citrus. In a 6(a)2 report
submitted to the Agency in 1990, Miles reported detections of the
parent fenamiphos in ground water on the study site that greatly
exceeded the 2 ppb lifetime Health Advisory. High levels of two of
the degradates, fenamiphos sulfoxide and fenamiphos sulfone, were
also found. Concentrations in ground water ranged up to 22.5 ppb,
204 ppb, and 19.9 ppb for the parent, sulfoxide degradate, and
sulfone degradate, respectively (DP Barcode D157194). The highest
level of total residues detected in ground water during one
sampling event was 239 ppb.
Following the receipt of the retrospective study information, EFGWB
recommended that a ground-water advisory be placed on the
fenamiphos label. A revised label with this advisory was issued in
1992.
In order to better define the fate of fenamiphos in the
environment, EFGWB requested that the registrant conduct a small-
scale prospective ground-water monitoring study (Memorandum from E.
Behl to Cynthia Giles-Parker, 1/13/92). The State of Florida also
requested a prospective study for this chemical because of its
citrus use. A protocol was submitted in 1993 (DP Barcode D193324,
8/25/93) for a study to be conducted in Florida, but the protocol
was found to be unacceptable by both the State of Florida and the
Agency. The study is anticipated to begin sometime in 1994,
primarily to satisfy the requirements of the State of Florida.
Environmental Fate Assessment
Fenamiphos and its degradates exhibit many of the properties and
characteristics associated with chemicals that have been detected
in ground water. Fenamiphos is mobile with Kd values that range
from 0.95 to 4.24 L/kg in sandy loam, silt loam, and clay loam
soils. The degradates, fenamiphos sulfone and fenamiphos
sulfoxide, are more mobile than the parent compound. An acceptable
study indicated that the aerobic half-life for fenamiphos was
approximately 16 days; other information reports half-lives up to
30 days for the parent. In addition, the anaerobic soil metabolism
half-life for parent fenamiphos is approximately 88 days (13 weeks)
which indicates that it will persist once it reaches ground water.
For these reasons, fenamiphos use is likely to have a significant
impact on ground-water quality.
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The lifetime Health Advisory for fenamiphos has been established at
2 ppb; Health Advisory levels have not been established for the
degradates. Fenamiphos has been classified as a D carcinogen which
indicates that there is inadequate evidence of carcinogenicity in
humans and animals or that no data are available. Although
monitoring has been conducted for fenamiphos in six states, and for
fenamiphos sulfoxide and sulfone in two, no detections of these
chemicals had been reported when the "Pesticides in Groundwater
Database" (Hoheisel et al., 1992} was published. However,
fenamiphos has been detected in ground water in Florida at
extremely high levels (see above) compared to human health
standards, and it therefore presents a concern to human health via
drinking water.
Because fenamiphos and its degradates are both mobile and
persistent under certain conditions, they are likely to have an
impact on ground-water quality. In addition, over the long term,
persistent pesticides that have leached to ground water will be
discharged to surface-water bodies (i.e., streams, rivers, lakes,
wetlands). Therefore, contamination of ground-water resources can
also have an impact on ecological endpoints. Based on our current
knowledge about these endpoints, fenamiphos may have an impact on
aquatic invertebrates and fish through ground-water discharge. No
information is presently available to assess any impacts that
fenamiphos may have on aquatic or terrestrial plants. As
illustrated on the accompanying graph, fenamiphos is not likely to
exceed some of the other risk-based levels of concern for
ecological effects.
Fenamiphos exceeds the following Levels of Concern for around
water:
~ GROUND-WATER QUALITY. EFGWB is concerned about the
potential degradation of ground-water quality that occurs in
fenamiphos use areas. Fenamiphos is registered for use on a
variety of terrestrial food and nonfood crops. Fenamiphos
and/or its degradates will probably be detected in ground
water in areas where these crops are grown on vulnerable
soils. This has already been demonstrated in Florida where
fenamiphos was applied to a citrus grove on vulnerable soils
and high levels of the pesticide and two of its degradates
were detected.
~ HUMAN HEALTH. Fenamiphos residues were detected in ground
water in Florida at levels which greatly exceeded the 2 ppb
lifetime Health Advisory. The concentration in ground water
for the parent alone ranged up to 22.5 ppb or approximately
1100 percent of the HA. Health advisory levels have not been
established for either of the fenamiphos degradates. Total
residues (parent and degradates) from the Florida study
exceeded the concentration qf the parent by over 10 times.
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* •' ¦*
Additional areas of concern:
~ ECOLOGICAL IMPACT.
Aquatic Invertebrates. Fenamiphos is highly toxic to
.some aquatic invertebrates, with an LCS0 for water fleas
(Daphnia magna) of 1.6 ppb. Fenamiphos is also
moderately toxic to pink shrimp (Penaeus duorarum) with
an LC50 of 150 ppb, Fenamiphos residues in ground water
could have an impact on aquatic invertebrates in areas
where ground water is discharged to surface water,
Fish. Fenamiphos is highly toxic to fish, with an LCS0
for bluegill sunfish (Leporois macrochirus) of 9.6 ppb,
and an LCS0 of 72.1 ppb for rainbow trout (Oncorhynchus
mykiss). Several fenamiphos-related fish kills * are
reported in the EPA Incident Database. Fenamiphos
residues in ground water could have an impact on fish in
areas where ground water is discharged to surface water.
Data requirements not satisfied
166-1. Small-Scale Prospective Ground-Water Monitoring. All data
are required.
Recommendations
1. Because fenamiphos exceeds certain Levels of Concern for
ground water, the GWTS recommended a ground-water advisory on
the fenamiphos label in 1992. In addition, EFGWB requested
that a prospective ground-water monitoring study be conducted
for fenamiphos. This study is scheduled to begin sometime in
1994.
2. Fenamiphos meets the persistence and mobility triggers for
classification as a restricted use chemical for ground-water
concerns. At the present time, insufficient monitoring
information is available to determine whether fenamiphos would
be classified as a restricted use chemical for ground-water
concerns. Additional monitoring may be required for this
chemical to determine whether all the restricted use criteria
are met.
3. In light of the acetochlor decision, the Ground Water
Technology Section recommends that several additional
prospective ground-water monitoring studies be conducted for
fenamiphos.
4. The GWTS recommends that the registrant attempt to make every
effort to stop the contamination of ground water by fenamiphos
residues. If contamination of ground water continues to occur
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from use in accordance with label directions or in accordance
with commonly recognized practices, the registrant should
consider voluntarily cancellation of this chemical in the
United States.
4. The GWTS requests a meeting with representatives from Miles,
Inc. to discuss fenamiphos use areas in the United States. The
locations for the prospective studies requested above will
depend on this information.
REFERENCES
Hoheisel, C., Karrie, J., Lees, S., Davies-Hilliard, L., Hannon,
P., Bingham, R., Behl, E., Wells, D., and E. Waldman. 1992.
Pesticides in Ground Water Database - A Compilation of Monitoring
studies: 1971-1991, EPA 734-12-92-001, September 1992.
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Comparison of Detections in Ground Water with Levels of Concern
FENAMIPHOS (Nemacur)
HUMAN HEALTH (2 ppb)
INVERTEBRATES
ENDANGERED FISH
FISH (acute)
plants
bird (chronic)
bird (acute)
mammal (chronic)
mammal (acute)
estuarine species
????
~l \ I I I IT
i ) —i—r'r i i n 11
ffilgFiest ground water
detection in retrospective
study (= 22 ppb)
lowest ground water detection in
retrospective study (= 0.1 ppb)
teifess
1
r i nil ij
I I II M | 1 1 I I I tl
0.01 0.10 1.00 10.00 100.00 1000.00 10000.00
Level of concern (LOG) in ppb
LOC EXCEEDED
No Concern at Present
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