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**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

WASHINGTON D.C., 20460

OFFICE OF

> PREVENTION, PESTICIDES AND
>
> TOXIC SUBSTANCES

**PC Code:** 058001

**DP Barcode:** 307569

> **DATE:** May 30, 2006

**[MEMORANDUM]{.underline}**

**SUBJECT**: Azinphos Methyl---EFED Response to Stakeholder Comments on
the Ecological Risk Assessment for "Group 3" Uses

**FROM:** Colleen Flaherty, Biologist (ERB 3)

R. David Jones, Chemist (ERB 4)

Environmental Fate and Effects Division (7507C)

**THRU:** Daniel Rieder, Branch Chief (ERB 3)

Elizabeth Behl, Branch Chief (ERB 4)

Environmental Fate and Effects Division (7507C)

**TO:** Diane Isbell, Risk Manager (RRB 2)

Special Review and Reregistration Division (7505C)

Number range CHAPTERAttached please find the Office of Pesticide
Program's (OPP's) response to stakeholder comments on the ecological
risk assessment for the use of azinphos methyl on apples, blueberries
(low- and high bush), Brussels sprouts, cherries (sweet and tart),
grapes, nursery stock, parsley, pears, pistachios, and walnuts (*i.e.*
"Group 3 uses").

**[Cherry Marketing Institute (EPA-HQ-OPP-2005-0061-0071)]{.underline}**

**1. Comment** (Page 3): "Using tree-row-volume technology and spraying
in the evening and at night when the winds are calm is a critical
practice that most growers have used to minimize drift."

**EFED Response:** Tree-row-volume technology and spraying at night may
indeed reduce spray drift. However, azinphos methyl is extremely toxic
to aquatic animals, and aquatic exposures of azinphos methyl are
predominantly runoff driven in the eastern United States. Thus, aquatic
risks would remain even if these spray drift mitigation techniques were
employed universally by cherry growers.

**2. Comment (**Page 3): "CMI believes that the Agency has
over-estimated the ecological risk when AZM is used on cherries. Over
the years, there have not been any adverse incidents resulting from the
use of AZM reported in our industry."

**EFED Response:** This statement assumes that there is a rigorous
ecological incident monitoring program in place. This is not the case.
Based on laboratory toxicity data, projected environmental exposures for
azinphos methyl use on cherries, and field studies in fruit orchards
(including one in Michigan), the risks to aquatic and terrestrial
animals remain.

**[Mark Whalon (EPA-HQ-OPP-2005-0061-0081)]{.underline}**

**1. Comment** (Page 4): "AZM did not produce detectable residues (below
LOD) in processed cherries in a 2-year independent study conducted in
Michigan (1998-9)... these data did not find their way into any of
USEPA's ecological or benefit analysis on AZM."

**EFED Response:** EFED does currently consider the residues on fruit at
harvest for use in the ecological risk assessment, although it is an
important part of the human health risk assessment. Ecological risks
accrue between application and harvest, so post-harvest data are not
relevant for our assessments.

**2. Comment** (Page 5-11): Acute & Chronic Toxicity Assessment:
Inference to Ecological Sustainability; beneficial insect indices.

**EFED Response:** EFED agrees that chronic (*e.g.* reproductive,
growth) Number range CHAPTEReffects can have profound ecological
consequences, such as alteration of the trophic cascade, reduction in
biodiversity, *etc*. Chronic azinphos methyl toxicity studies were
available for a number of aquatic and terrestrial animals, and these
studies have been reviewed and incorporated into the ecological risk
assessment.

Dr. Whalon's comments focus on the ecology of beneficial insects in
agricultural settings. The EPA assessment took into consideration *all*
aquatic and terrestrial animals (including beneficial insects) and
plants in the United States. The Number range CHAPTERaquatic ecosystems
potentially at risk include water bodies adjacent to or downstream from
the treated field. These water bodies include impounded bodies such as
ponds, lakes, and reservoirs; and flowing waterways, such as streams and
rivers; and marine ecosystems, including estuaries. The terrestrial
ecosystems potentially at risk include the treated area and areas
immediately adjacent to the treated area that might receive drift or
runoff. These terrestrial ecosystems include other cultivated fields,
fencerows, hedgerows, meadows, fallow fields, grasslands, woodlands,
riparian habitats, other uncultivated areas.

EPA's ecological risk assessment concluded that all of the remaining
azinphos methyl uses pose chronic (and acute) risks to all aquatic and
terrestrial animals (including beneficial insects). These risk
presumptions are supported by various field studies and adverse
ecological incidents, including numerous beneficial insect kills.

**[Bayer CropScience (EPA-HQ-OPP-2005-0061-0092)]{.underline}**

**1. Comment** (Page 4): "The modeled water concentrations that were
used in the aquatic risk assessment (Page 39, Table 3.12) were much
higher than the actual concentrations observed in monitoring."

**EFED Response:** Comparisons between modeling and monitoring need to
consider (among other things) 1) differences in hydrologic setting
between the modeled scenario and the monitoring data; 2) use patterns in
the monitoring data; 3) the return frequency in the modeling versus the
study duration for the monitoring; 4) sampling frequency in the
monitoring.

The hydrologic setting for the aquatic modeling represents a pond that
is located high in the watershed and is more vulnerable than most sites
where the specific crop is grown. The watershed is assumed to be
dominated by the production of a single crop. It is a surrogate for
other small vulnerable water bodies near the tops of watersheds such as
playa lakes, prairie pot holes, vernal pools, and first-order streams.
In contrast, most monitoring data are collected on larger creeks,
rivers, and reservoirs where dilution by untreated water and dissipation
processes have had some opportunity to reduce the concentration from
that of water bodies close to the application site. For example, in the
Pilot Reservoir Monitoring Study, the smallest watershed was Lake LeRoy
in New York, with an area of 3.3 square miles.

In order to evaluate monitoring data, it is important to know the use
intensity and application timing in the basin upstream of the sampling
station. However, this information is usually not available. None of the
studies listed in Bayer's comment (Pilot Reservoir Monitoring Study,
NAWQA, STORET, NAWQA phase pilot monitoring program, and the Washington
State Surface Water Monitoring Program) were targeted to azinphos methyl
usage or to crops on which azinphos methyl may be applied. In some
cases, the usage or potential usage can be evaluated *post hoc*, as was
done for the final EFED ecological risk assessment supporting the RED.

Monitoring data are collected from several sites, but only a few years
in time. Simulation modeling represents longer periods of time at each
site. Currently, 30 years is usually simulated, and the 1-in-10 year
concentration is used for screening risk assessment. The 1-in-10 year
concentration will be greater than more frequent return periods. For
example, for the Pennsylvania apple scenario, the 1-in-10 year return
value with a 25-ft buffer was 15.0 μg L^-1^, while the 1-in-2 year value
is 9.7 μg L^-1^.

Tier-2 simulation modeling estimates the concentration in the surrogate
water body every day for 30 years, which results in over 10,000 daily
concentration estimates. In contrast, monitoring data usually only have
a few measurements at each location due the relatively large expense
required to collect and analyze each sample. Studies with a high
frequency of monitoring typically have 12 to 20 samples taken in a year,
resulting in several hundred samples analyzed from all sites in the
course of the study. Unless the monitoring study is correlated with
pesticide application schedules, it is unlikely that the highest
concentrations that occur during the study period will be captured.
Consequently, using monitoring data alone to assess acute aquatic risks
will usually underestimate the actual risks. Monitoring data tend to be
more useful in establishing chronic exposure estimates for risk
assessment purposes, provided that the sampling schedule adequately
captures the pesticide's presence at the sampling site.

Based on the combination of all of these factors, in general, monitoring
data underestimate the exposure of pesticides in the environment
especially for pesticides where the short-term or one-time exposure
elicits an effect of concern. Tier-2 modeling is used by EPA as a
screening tool and may overestimate actual exposures. Real-life
exposures generally lie between the estimates from these two methods.

**2. Comment** (Page 6): "The label specifies medium or coarser spray,
applications when wind velocity favors on-site product deposition, use
during dormant season prohibited..."

**EFED Response:** EFED's current model for spray drift from air blast
is a regression model and is unable to account for spray quality (*e.g.*
medium or coarser spray). (Note that the labels specify spray quality
only for aerial and ground boom applications). Wind speed effects also
cannot be directly accounted for as the original calculations on which
the model is based could not separate wind speed effects from the
background variability. Contrary to the comment, EFED did not simulate a
dormant application. EFED simulated a sparse orchard to account for air
blast spraying over the top of the orchard. The current labels indicate
that this practice is, in fact, restricted on the label ("To minimize
spray loss over the top in orchard applications, spray must be directed
into the canopy.") and a new simulation has been prepared that uses the
'normal' rather than the sparse orchard. Additional modeling has been
done using the standard orchard ("Orchard" in AgDrift), rather than the
sparse orchard, and the risks to aquatic animals remain.

**3. Comment** (page 6): "Increasing drift value by a factor of three
was not necessary, since the value generated by AgDrift was already
conservative."

**EFED Response:** As noted above, the spray blast model in AgDrift is a
regression model, and as such, predicts the mean estimate across the
trials that were used in the regression calculation. Consequently, about
half of the time, the spray drift deposition will be higher; the other
half of the time, it will be lower. Multiplying the pond deposition
accounts for this background variability and assures that the screening
estimate will be conservative.

**4. Comment** (Page 6): "Aerial application is prohibited on the label"

**EFED Response:** There is an SLN label for aerial application to
apples in Idaho. The estimate with aerial application only applies to
that label. The Oregon apples scenario was used as a surrogate for
apples grown in Idaho. Ground spray application was also modeled for
apples.

**5. Comment** (Page 6): "The models do not take into account the
dilution that can be attributed to the runoff water and sediment
reaching the water body. Also, the models do not take into account the
mass of pesticide removed from the pond by overflow."

**EFED Response:** The volume of the pond is several times the volume of
runoff from a 10 hectare field even in the largest runoff events. For
example, a large runoff event may generate 5 cm (about 2 inches) of
runoff per hectare, which is equivalent to 5 million liters. There are
20 million liters in the pond, so the dilution in the pond is larger
than that for dilution in the runoff. The EXAMS model is a steady-state
model, and it cannot estimate storm-by-storm runoff. Setting a single
steady-state flow tends to underestimate potential exposure
substantially, partly because the release from the pond is too great,
and partly because real ponds also evaporate, which concentrates the
pesticide between storm events. Consequently, the pond scenario is set
so there is no flow out of the water body. This is equivalent to
assuming that evaporation and runoff are equal, which is a reasonable
assumption for many small static water bodies.

**6. Comment** (Page 10-11): "For aquatic species, detailed field
studies have been conducted by a number of researchers... Based on the
results of these studies, Bayer CropScience believes that the No
Observed Adverse Effects Concentration (NOEAC) for azinphos-methyl to
aquatic organisms is near 1 ppb (µg a.i./L)."

**EFED Response:** Number range CHAPTERThe studies that Bayer
CropScience refers to suggest that a *single* exposure of azinphos
methyl at a very low level (*i.e.* 4 µg a.i./L) can elicit
*population-level* effects in aquatic ecosystems (Number range
CHAPTERSierszen and Lozano, 1997). At this level, taxon richness
(diversity) was significantly reduced, and recovery of zooplankton
populations and communities took one month. Most of the remaining
azinphos methyl uses allow more than one application per season, and we
would expect that the magnitude of the population declines and the time
to recover would increase with increasing applications.

In addition, chronic toxicity studies indicate that significant
reproductive effects can occur at levels well below 1 µg a.i./L. In a
21-day *Daphnia magna* chronic toxicity study, significant effects on
survivorship, length, and fecundity (mean number of young per adult per
reproductive day) were observed at a LOAEC of 0.40 μg a.i./L. For these
reasons, a NOAEC of 1 µg a.i./L for aquatic organisms (as suggested in
the comment) would not be adequately protective for azinphos methyl.

**7. Comment** (Page 11): "...significant reduction in both aquatic and
terrestrial incidences reported in association to labeled uses..."

**EFED Response:** Cancellation of the use of azinphos methyl on both
sugar cane and cotton, in particular, undoubtedly reduced the ecological
risks associated with this chemical. However, the risks associated with
the remaining uses of azinphos methyl are still very high. Our
assessment concluded that there are acute and chronic risks to all
potentially exposed aquatic and terrestrial animals for all of the
remaining labeled uses.

Further, the trend of decreasing adverse ecological incidents in the
EIIS database is not unique to azinphos methyl. Reports of adverse
ecological incidents have dropped dramatically since 1995. We suspect
that this decline is more of a result of reduced reporting rather than
to a drastic decrease in pesticide risk to fish and wildlife.

**8. Comments**

(Page 14): "...While model predictions indicate dietary exposure via
residues in excess of mortality thresholds, no terrestrial incidence has
appeared in the EIIS Pesticide Report since 1999. BCS feels this is
indicative of the probability of effects likely elicited in the field
with current use patterns."

(Page 14): "The reference to terrestrial incidents should be qualified
with the fact that none have been reported since 1999. BCS believes this
is related to current label uses and the reduced probability of
effects."

(Page 18): "Former field incidences are not in line with current trends
associated with current uses. No terrestrial incidence has appeared in
the EIIS Pesticide Report since 1999."

(Page 18): "While LOCs are exceeded for these uses, terrestrial
incidence reports have not occurred since 1999."

(Page 23): "The assumption that mitigation measures would not reduce
risk potential is unsubstantiated. While the Agency's LOCs have been
exceeded for terrestrial for many uses patterns the predicted effects
have not been realized under true field exposure condition in recent
years (i.e. no terrestrial incidence reports since 1999)."

(Page 23): "No terrestrial incidence has been reported since 1999. BCS
believes this to be a direct correlation to use mitigation and effective
best management practices employed since that time."

**EFED Response:** Number range CHAPTERThese statements assume that
there is a rigorous ecological incident monitoring program in place.
Wildlife incidents from exposure to an environmental stressor may go
unnoticed by humans because dead wildlife can be easily overlooked, even
by experienced and highly motivated observers. Reasons for
underreporting of wildlife incidents include:

-   Wildlife carcass detection is difficult in areas with sparse
    vegetative cover and nearly impossible where there is dense
    vegetative growth.

-   Birds may fly from the poisoning site, and intoxicated animals often
    seek cover before dying.

-   Scavengers may remove carcasses before they can be observed by
    humans. Balcomb *et al.* (1984) reported that the removal rate of
    songbird carcasses by scavengers ranged from 62 to 92 percent in the
    first 24 hours following placement.

-   The density of live birds in agricultural settings is typically low.
    Thus, even if all the birds in a field were killed and remained on
    the field, the probability of detecting carcasses, particularly when
    not systematically searching, is very low. Even when highly-trained
    individuals conduct systematic searches for placed carcasses in
    agricultural environments, recovery rates rarely exceed 50 percent
    (Madrigal *et al*., 1996).

-   If wildlife kills are observed, they are not always reported to the
    Agency. Those unfamiliar with the potential ecological effects of
    pesticides may fail to associate the dead wildlife with a pesticide
    application, especially if the two events are separated by several
    days or the kill magnitude is low. If the observer makes the
    connection, he must still be motivated enough to report the incident
    to the Agency.

Further, the trend of decreasing adverse ecological incidents in the
EIIS database is not unique to azinphos methyl. Reports of adverse
ecological incidents have dropped dramatically since 1995. We suspect
that this decline is more of a result of reduced reporting rather than
to a drastic decrease in pesticide risk to fish and wildlife.

**9. Comment** (Page 15): "EFED presents no argument supporting the
expected commensurate toxicity associated with azinphos-methyl
degradates. It is unreasonable to assume degradates would magnify
potential risk to aquatic organisms without factual

substance. This statement by EFED is later contradicted on page 20 of
the EFED risk assessment as follows: "Furthermore, none of the
degradates that are produced by metabolic pathways, which are the
primary routes of degradation for azinphos-methyl, are present at any
time at concentrations greater than 10% of the nominal starting
concentration of the parent, so they would not be expected to contribute
substantially to total toxicity of azinphos-methyl in the environment."

**EFED Response:** The risks from the parent alone exceed the risk
thresholds. There are some environmental degradates, particularly the
azinphos methyl oxon, that are potentially toxic. Oxons of other
organodithiophosphates are more toxic than the parent. OPP often makes a
default assumption that degradates are of equal toxicity to the parent
when data has not been provide to the contrary. However, azinphos methyl
degradates have not been found in the significant quantities in the
environment, and they were not considered quantitatively in the risk
assessment. To the extent they are present they increase the risk above
what has been estimated for parent, which is already above the Agency's
levels of concern for non-target species.

**10. Comment** (Page 16): "No aerial use is included on the pending
label in Idaho."

**EFED Response:** There is still an active 24(c) in Idaho for aerial
application on apples. The SLN number is ID000006.

**11. Comment** (Page 16): "The pending use label does not include
grapes."

**EFED Response:** At the time the assessment was written, there was an
active 24(c) for azinphos methyl use on California grapes.

**12. Comment** (Page 16): "The pending Group 3 label for
azinphos-methyl states that a medium to coarse spray nozzle should be
used (according to ASAE 572 definition for standard nozzles) for ground
boom and aerial applications. AgDrift inputs should have

been made using a medium to coarse droplet size."

**EFED Response:** EFED agrees that the assessment of aerial application
for Idaho should have used a medium spray. However, the risk conclusions
would not change if medium spray was used for this use.

**13. Comment** (Page 17): "The Guthion Solupack label (264-733) is
pending for the current uses included in this assessment. Therefore,
broadcast spray for Brussels sprouts should not be included.
Incorporation or in furrow spraying should have been assessed thus
reducing spray drift potential."

**EFED Response:** The current label allows broadcast spray on Brussels
sprouts and that practice was the one used for the risk assessment. If
Bayer has submitted alternative use language for Brussels sprouts, it
can be evaluated as part of the continuing re-evaluation process for
azinphos methyl.

**14. Comment** (Page 17): "The pending Group 3 label for
azinphos-methyl does not include aerial application to apples."

**EFED Response:** There is still an active 24(c) in Idaho for aerial
application on apples. The SLN number is ID000006.

**15. Comment** (Page 17): "The vast majority of these 130 reported
adverse aquatic incidences come from the late 1980's and early 1990's on
uses no longer labeled and are therefore not relevant to current label
uses."

**EFED Response:** Cancellation of the use of azinphos methyl on both
sugar cane and cotton, in particular, undoubtedly reduced the ecological
risks associated with this chemical. However, the risks associated with
the remaining uses of azinphos methyl are still very high. Our
assessment concluded that there are acute and chronic risks to all
potentially exposed aquatic and terrestrial animals for all of the
remaining labeled uses.

**16. Comment** (Page 22): "EFED concludes that risk quotients suggest
expected mortality and/or sub-lethal effects, incident data and surface
water monitoring data since 2001 (since significant mitigating practices
have been implemented) suggest a low probability

of such effects."

**EFED Response:** As discussed above, because monitoring data generally
underestimate acute risk, it cannot be used to rule out risk above the
level of concern. Further, the slope of the dose-response curve for
azinphos methyl is very steep, and small exceedance of effects
thresholds can elicit profound ecological effects.

**17. Comment** (Page 24): "The studies performed were level 1 field
studies which are designed to provide only qualitative information about
effects. They were not designed to quantify the magnitude of effects
occurring."

**EFED Response:** These field studies were used in a qualitative manner
and only to provide additional lines of evidence in the ecological risk
assessment.

[**U.S. Apple Association**
**(EPA-HQ-OPP-2005-0061-0087.2)**]{.underline}

**1. Comment** (Page 2): "...spray drift model assumes that wind is
always blowing in the direction of its hypothetical farm pond at the
highest allowable wind velocity, the vegetation cover is sparse and the
drift value is multiplied by three. The water model calculates loading
of the pesticide in the pond assuming that all orchards are composed of
soils with high runoff potential. Additionally, the water model counts
pesticide runoff carried by water into the pond, counting only the
pesticide deposition and not the water....This model compounds the
pesticide loading scenario by restricting natural out flow of the pond.
Also, it does not count the run off reduction from the 25 foot buffer
which is required on the azinphos methyl label, and it does not include
the run off reduction from a vegetative buffer between the pond and the
hypothetical farm field. This assumption contradicts the real scenario
in apple production. These assumptions reflect the most conservative
scenario for azinphos methyl use, not a realistic scenario."

**EFED Response:** The U.S. apple association is correct that EFED
modeling assumes that the wind is always blowing directly at the pond.
Currently, available spray drift models do not have the capability to
account for wind direction, so assuming that the wind always blows
towards the pond allows the assessment of spray drift in the absence of
such a capability. Sparse orchards can be used to represent dormant
applications (which are prohibited on the label) as well as applications
to immature orchards and to address the drift from applications that go
over the top of the canopy. For these simulations, it was this last case
(over the top of the canopy) which was the justification for using the
sparse orchard. However, there is language on the label which indicates
that practice is prohibited, so it was incorrect to use a sparse orchard
on that basis. Additional modeling has been performed with a generic
orchard rather than the sparse orchard to correct this error. Predicted
exposures are somewhat lower; however, risks still exceed the Agency's
level of concern.

The modeling considered spray drift buffers, but not run-off buffers. A
high runoff potential soil is used in the scenario so that the
simulation will account for the most sensitive areas where there are
apple orchards, in general. Vegetative buffers are not expected to
meaningfully reduce azinphos methyl movement to water unless they are
specifically constructed and maintained for that purpose. Otherwise,
water tends to flow along the buffer to a low point and cross the buffer
as concentrated flow with little or no mitigation effect. EFED does
believe that the use of constructed and maintained Vegetated Filter
Strips (USDA NRCS 2000) can reduce the potential for runoff. However,
tools are not currently available to quantify the expected reduction in
runoff when this mitigation practice is used.

An explanation for dilution effects in pond is provided in the response
to comment #1 from Bayer CropScience.

**2. Comment** (Page 2): "EPA's modeling scenario utilizes data that are
inconsistent with monitoring data measuring real azinphos methyl
concentrations in water bodies across the United States. In its
Pennsylvania air blast modeling scenario EPA generates a concentration
of 15.1 parts per billion (ppb) and 9.9 ppb for its Oregon air blast
scenario. However, STORET and U.S. Geological Survey (USGS) monitoring
data indicate azinphos methyl concentrations are mostly 1 ppb or less,
with two peak values of less than 4 ppb between 1990 and 2005. After
2001, the highest concentrations from actual monitoring data were 0.75
ppb in Oregon and less than 0.05 ppb in Pennsylvania."

**EFED Response:** Explanation for differences in modeling and
monitoring are discussed in the response to comment #1 from Bayer
CropScience.

**3. Comment** (Page 2): "...EPA's ecological risk assessment fails to
provide the full context when discussing azinphos methyl detections in
Washington state. While stating on pages 39-40 that azinphos methyl was
detected in a high percentage of samples collected by USGS in 1999 and
2000, the agency does not mention that more than 95 percent of the
detections were below 0.1 ppb. The assessment also omits USGS data that
would reflect significant usage changes resulting from azinphos methyl
label changes in 2002 and 2003. USGS data indicate that between 2001 and
2004 in Washington state there were 408 azinphos methyl samples with a
maximum value of 0.18 ppb with only 7 samples with concentrations above
0.05 ppb."

**EFED Response:** EFED agrees that azinphos methyl was detected in a
large number of samples at relatively low concentrations. EPA did not
re-evaluate all available monitoring data for this assessment; however,
monitoring data evaluated for one site, Granger Drain, indicated a
similar trend, with a high percentage of azinphos methyl detections at
low concentrations during the application season (May 20-August 31). The
maximum concentration, 0.18 μg/L, was reported in 2003. Samples were
collected at most on a weekly basis. There was no discernable trend in
concentrations at that site to correlate with a decline in azinphos
methyl usage referred to in the comment. In approximately weekly
sampling from 1999 to 2004 (except 2000), detection frequency ranged
from 76% in 2003 to 100% in 2001 and 2002. Only two samples were
collected during the application season in 2000. There were also no
apparent trends in concentration during the application season as well.
Monitoring in the NAWQA program for the most part reflects larger
streams and rivers that reflect a wide variety of land uses in the
basin. Smaller water bodies will have higher aquatic exposures of
azinphos methyl.

**4. Comment** (Page 2): "The weight of the evidence from available
monitoring data indicates that azinphos methyl concentrations are
significantly lower than the hypothetical values used in the ecological
risk model to calculate ecological impacts from azinphos methyl.
Additionally, the monitoring data indicate that these values have
continued to decline as EPA has imposed greater restrictions on azinphos
methyl use. These factors are strong indicators that EPA's model
overestimates the ecological risk, since real measurements of azinphos
methyl are significantly lower than the hypothetical values used in the
model."

**EFED Response:** A cursory analysis of the monitoring data from
Washington did not support the claim that concentrations in surface
waters have declined in all areas, although that may be the case in
areas where agriculture is dominated by crops on which azinphos methyl
can no longer be used (*e.g.* sugar cane). EFED believes that the
monitoring data do not reflect the full potential for toxic exposures to
azinphos methyl as discussed above (in the response to comment #1 from
Bayer CropScience). Available monitoring data are collected at most on a
weekly basis and would be expected to result in lower concentrations
than are estimated by the 1-day modeling time-step. EFED's Tier-2
simulation modeling is conservative by design and estimates risk for
locations that are most vulnerable to ecological risk. The
concentrations to which aquatic organisms are actually exposed probably
fall somewhere between the monitored and modeled results. Since there
continues to be some monitoring measurements above the level of concern,
based on these results alone, we would expect there to be some adverse
environmental impacts as a result of azinphos methyl use.

**5. Comment** (Page 2): "...the absence of recent adverse ecological
incidences indicates that previous label modifications have been
effective in reducing the ecological impact of azinphos methyl use. The
dearth of such incidents also suggests that EPA's theoretical risk model
overstates the real risk from azinphos methyl use. As an example, most
previous incidents were caused by uses on cotton or sugarcane which are
no longer labeled for use. Additionally, there have been no reported
incidents since 2001."

**EFED Response**: Cancellation of the use of azinphos methyl on both
sugar cane and cotton, in particular, undoubtedly reduced the ecological
risks associated with this chemical. However, the risks associated with
the remaining uses of azinphos methyl are still very high. Our
assessment concluded that there are acute and chronic risks to all
aquatic and terrestrial animals for all of the remaining labeled uses.

Further, the trend of decreasing adverse ecological incidents in the
EIIS database is not unique to azinphos methyl. Reports of adverse
ecological incidents have dropped dramatically since 1995. We suspect
that this decline is more of a result of reduced reporting rather than
to a drastic decrease in pesticide risk to fish and wildlife. In recent
years, state budget shortfalls have caused many states have cut funding
for programs responsible for investigating and reporting fish and
wildlife mortality incidents.

**[Citations]{.underline}**

Number range CHAPTERBalcomb R, Stevens R, Bowen II C. 1984. Toxicity of
16 granular insecticides to wild-caught songbirds. *Bull. Environ.
Contam. Toxicol*. 33:302-307.

Number range CHAPTERMadrigal JL, Pixton GC, Collings BJ, Booth GM, Smith
HD. 1996. A comparison of two methods of estimating bird mortalities
from field-applied pesticides. *Env. Tox. Chem*. 15:878-885.

USDA NRCS. 2000. *Conservation Buffers for Reducing Pesticide Losses.*
Natural Resource Conservation Service. Fort Worth, TX. 21 pp.