Document ID: EPA-HQ-OPP-2007-0350-0174
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-07-16T04:00Z

SEQ CHAPTER \h \r 1 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF

PREVENTION, PESTICIDES, AND

TOXIC SUBSTANCES

PC Code:  081501

DP Barcode: 348669

	

						Date:  April 16, 2008

MEMORANDUM								    

SUBJECT:	1) Response to Phase 5 Public Comments on the Phase 4
Chloropicrin Reregistration Risk Assessment and 2) Revised Chloropicrin
Reregistation Risk Assessment 

TO:		Andrea Carone, Risk Manager Reviewer 

		Richard Dumas, Risk Manager

Special Review and Reregistration Division (7508P)

FROM:	Faruque Khan, Senior Scientist

		James Felkel, Wildlife Biologist

		Environmental Risk Branch V		

Environmental Fate and Effects Division (7507P)

Approved	Mah Shamim, Branch Chief

 By:		Environmental Risk Branch V		

		Environmental Fate and Effects Division (7507P)

		

The Environmental Fate and Effects Division (EFED) has completed its
review of comments from the Chloropicrin Manufacturers’ Task Force
(CMTF) (Data Package: EPA-HQ-OPP-2007-0350) received during the public
comment period (Phase 5) on the environmental fate and ecological risk
assessment for chloropicrin.  EFED has not received any other comments
on chloropicrin during this phase. 

To facilitate response, CMTF comments are in italics below, followed by
the EFED response.  The intent of EFED’s review is to address various
environmental fate and ecological risk assessment issues. Comments
regarding human health and worker exposure issues will be addressed
separately by the Health Effects Division. The EFED assessment has been
formally revised twice previously.  Most of the CMTF comments are a
response to our previous response (4/5/07) to their comments. 

CMTF Comment:

(p. 57) A. Estimates Are Overly Conservative

Adequate conservatism is already accomplished via the Level of Concern
(LOC)

index. For example, for aquatic species exposure, the Endangered Species
LOC is 0.05.

This equates to a safety margin of 20X above the model-predicted peak
Estimated

Environmental Concentration (EEC). Given the numerous assumptions and
limitations of

the model, the safety margin quickly rises to 100X or more, since all or
most of what

EFED considers “uncertainties” overestimate the EECs.

EFED Response:  The established Endangered Species LOC of 0.05 is not a
20X safety margin.  It was established years ago to estimate an
individual effect level based on the LC50.  None of the LOCs involve any
added safety factors.

CMTF Comment:

(p. 57) ecological set-backs are not the best approach for addressing
ecological issues

EFED Response:  The EFED risk assessment did not discuss or evaluate
“ecological set-backs” at all.  

CMTF Comment:

(pp. 58 – 59) In the Risks of Chloropicrin Use to Federally Listed
Threatened

California Red Legged Frog (Rana aurora draytonii) (Khan and Felkel
2007), the

Agency used the PERFUM model to incorporate more realistic
meteorological effects on

chloropicrin air concentrations, which is in contrast to the Agency’s
reliance on the

ISCST3 model the Phase IV Ecological Risk Assessment for Chloropicrin.

EFED Response:  EFED used both of the above models in the refined
California Red Legged Frog (CRLF) assessment.  It did not simply replace
ISCT3 with PERFUM.  As indicated in that assessment, PERFUM scenarios
not involving extrapolation to the maximum current application rate do
not exceed the ES LOC.  The mammal RQ using the ISCT3 model is 0.17 (as
indicated in the 4/07 RED risk assessment and the CRLF assessment) and
0.037 using the PERFUM model (without extrapolation to the maximum
current application rate).

CMTF Comment:

(p.59)  Effects of chemicals on wildlife when applied to an agricultural
field

usually diminish with distance, and chloropicrin is no exception. Thus,
it is necessary to

examine the likely effects of chloropicrin under realistic application
scenarios. As cited

above from MRID#441492-01, the maximum chloropicrin air concentrations
on the field

or at the field edge are likely to be below 1.5 ppm at the ground-level
height (15 cm), and

even less than this at higher heights (33 cm, 55 cm, and so on;
decreasing as height

increases). Birds generally have no opportunity to build nesting sites
at the edge of

treated fields during active farming practices. The field preparation
measures, such as

soil tilling, performed prior to fumigant application would have already
disturbed these

animals and discouraged close-by activity, including nesting. Nesting
sites could be

located some distance away from the field, but emitted chloropicrin
vapors would

disperse, dilute, and degrade rapidly, as measured in the offsite
monitoring data from this

same study. The CMTF maintains that chloropicrin field use as a soil
fumigant poses no

risk to avian species.

EFED Response:  One of EFED’s concerns is that sublethal air residues
could still be highly irritating to terrestrial wildlife and could
potentially cause nesting disruption, for example.  Potential sublethal
effects such as this are now being considered when evaluating impacts to
endangered species.  It is not clear how far from a treated field such
effects could potentially occur (or, conversely, at what distance
maximum air residues would no longer have the potential to cause such
effects).

CMTF Comment:

(p. 60)  As cited in our previous comments, ambient air concentrations
of chloropicrin have been measured over extended periods of time in
high-use areas during the active fumigation season, and the results
indicate that chloropicrin concentrations from multiple,

simultaneous and/or sequential applications even in a relatively small
area are well below

any level of concern for chronic risks to wildlife due to the rapid
environmental

breakdown of chloropicrin.

EFED Response:  Acute sub-lethal exposure may be the greatest concern
for terrestrial wildlife (see above).  Nevertheless, since EFED does not
have any chronic/sub-chronic data on birds, it is not possible to say
whether repeated or longer-term exposures potentially pose an added
risk.

CMTF Comments on EFED Response: (p. 60)

EFED Comment: EFED’s methods for estimated surface water
concentrations use

standard modeling procedures and input parameter guidance that have been
subject to

rigorous internal and external quality assurance review.

CMTF Response:

These reviews largely, and possibly exclusively, may have consisted of
generic assessments to develop a broad tool, such as PRZM/EXAMS.
However, the reviews, standard modeling procedures and input parameter
guidance likely did not address the need for additional model
refinements required for a valid assessment of soil fumigants, which are
used and applied in manners very different from most other pesticides
and have physiochemical properties unlike most other pesticides for
which PRZM/EXAMS may be more useful (e.g., foliar-applied insecticides).

The Overview of the Ecological Risk Assessment Process in the Office of
Pesticide

Programs, U.S. Environmental Protection Agency: Endangered and
Threatened Species

Effects Determinations (2004) document clearly states that, “…that
the ecological risk

assessment process within OPP may, on a case-by-case basis, incorporate
additional

methodologies, models, and lines of evidence that are technically
appropriate for risk

management objectives.” 

CMTF encourages EFED to look at additional models now available, such as

CHAIN_2D, for a more refined assessment of wildlife exposure risks.

EFED Response: 

Application methods of fumigant such as subsurface injections or drip
irrigation are no different than many other conventional pesticide
application methods. Many physiochemical and fate properties used in
PRZM/EXAMS for fumigants are comparable with other pesticides except
vapor pressures, which are considerably higher for fumigants and may
require tarping or other surface sealing methods to insure adequate
exposure at the site of application. To capture th0e effects of high
vapor pressure, additional physical parameters such as vapor-phase
diffusion in air and enthalpy of vaporization were used in PRZM/EXAMS.
The Agency believes that PRZM and EXAMS models are practical tools to
estimate surface water exposure. EFED is aware of the CHAIN_2D model. At
present, EFED will not be able to consider CHAIN_2D model to refine
current exposure assessments prior to Agency’s approval.

The registrant is correct that additional refinements can be made to
exposure/risk assessments; however, as the registrant has also noted,
such refinements are made at the request of the risk manager should
additional information be necessary to inform their decision.  

CMTF Comment: (p. 61) Chemical Volatilization and Temperature Effects: 

This uncertainty overestimates the EECs. EFED acknowledges that the
PRZM/EXAMS model likely overestimates the Estimated Environmental
Concentrations (EECs) for chloropicrin due to its inherent limited
capabilities in capturing the partitions of volatile chemicals, such as
chloropicrin, in air, water and sediment. Simply stating that the model
has these limitations does not address the error, nor is it a valid
approach to simply chalk this error up to an ambiguous, undefined
“uncertainty” that requires no further evaluation. A more
appropriate approach is to account for these limitations by adjusting,
to the degree possible, the model input parameters, operative features,
or other means of correction. 

EFED Response:

EFED acknowledges that the earlier version of PRZM (v3.12) had limited
capabilities in capturing the partitioning of volatile chemicals into
various environmental compartments (media). EFED replaced the earlier
version with PRZM (V3.12.2, May 2005), which accounts for the
partitioning of volatile chemicals in various media. Exposure assessment
for Phase VI of reregistration will be performed with enhanced version
of PRZM (V3.12.2). However, EXAMS accounts for partitioning of volatile
chemicals from surface water using Henry’s Law Constant.  

CMTF Comment: Additionally, it appears that a constant soil temperature
of 25OC was modeled, which likely underestimates actual soil temperature
in many areas. This is an important parameter for EFED to reconsider,
since available research demonstrates that in-soil degradation of
chloropicrin is greatly enhanced by increasing temperatures. Gan et al.
(2000) observed that at a soil temperature of 50OC, the degradation rate
of chloropicrin was 8, 11, and 7 times greater than at 20OC for three
different soils. At 40OC or greater, the soil half-life of chloropicrin
ranged from 0.05 to 0.7 days (1.2 to 16.8 hours). Soil temperatures also
would be significantly higher during tarped applications than non-tarped
applications, leading to a significant increase in soil metabolism. EFED
should model the effect of higher soil temperatures on soil degradation
rates and predicted EECs.

EFED Response:

EFED agrees with the registrants’ comments regarding the Gan et al.
study. However, in subsurface soil, temperature does not fluctuate like
the temperatures used by Gan et al. (2000). For example, soil
temperatures at 6 inches depth in Fresno, CA show minimal fluctuations
relative to daily air temperature. Annual fluctuation recorded between
10°C (50°F) to 27°C (80°F) for maximum temperature and 9°C (47°F )
to 25°C (77°F)  for minimum temperature (see attached data (page 12
from CIMIS). Also, the majority of fumigation activities occur during
late fall and early spring when temperatures are relatively mild. In
contrast to CMTF assumption for higher temperature, at lower soil
temperatures the degradation rates would also be lower and would likely
counteract any temperature effects; therefore, it is reasonable to
estimate environmental concentrations using a constant temperature of
25°C during PRZM simulation. EXAMS model accounts for the atmospheric
temperature difference using Q10 function during the simulation. 

CMTF Comment: (p 62-63) Tarping Effects: 

This uncertainty also overestimates the EECs. The effects of rain events
on treated fields, tarped and non-tarped, are not well established by
EFED and are not appropriately accommodated in PRZM/EXAMS modeling. The
unknown effect of tarping was acknowledged by EFED, but it does not
appear to have been appropriately accounted for in the models. In our
meeting with EPA on March 8, 2007, EFED indicated it accounted for tarp
effects. However, Waterborne Environmental (Ritter 2007) found no
evidence in the model inputs that any adjustments were made to account
for the effect that tarps would have on the amount and rate of
chloropicrin incorporation into rain water and subsequent field runoff.
EFED’s position on this issue seemed to be that chloropicrin would
still volatilize through the tarps and be captured by rainfall,
apparently at 100% capturing efficiency. In other words, EFED appears to
have assumed a 100% efficient and instantaneous wet redeposition of
chloropicrin vapors through the tarp. If this is an accurate
interpretation of EFED’s comments during the meeting, there appears to
have been no actual mathematical accounting in the agency’s
calculations to date for the actual effects of tarps. This step should
be taken.

EFED Response:

The CMTF ’s asserts that EFED assumed a 100% efficient and
instantaneous wet redeposition of chloropicrin vapors through the tarp.
To support this position, CMTF cites the March 8, 2007 discussion
between EFED Scientist in EFED and the members of CMTF. However, EFED
Scientist’s testimony is taken out of context by the CMTF. In the
“Conceptual Model” section environmental fate assessment in support
of Phase IV of reregistration, EFED stated that the contribution from
wet deposition to exposure will be negligible (page 18), and is
therefore discounted in the exposure assessment due to rapid degradation
of the chemical through atmospheric degradation. However, EFED Scientist
was disagreeing in principle with the CMTF manipulation of weather data
by entirely discounting rain events during fumigant-treated tarped
fields. EFED Scientist described in general terms, that in some cases
wet deposition plays an important role for pesticide exposure in
terrestrial and aquatic environments. EFED Scientist reiterated that
rainfall also has other significant roles in subsurface hydrologic
processes, and as such can not be discounted.  Please see response to
the comment below for further explanation why EFED disagrees with
discounting rainfall events in the PRZM/EXAMS modeling.

CMTF Comment: (p. 63)

Waterborne Environmental (Ritter 2007) used a different, more accurate
approach to account for the effects of tarps. In these model
simulations, rainfall was turned off until the tarp was removed. In this
way, Ritter’s modeled tarp effect better reflects reality in that the
tarp, being in place during and for 5 or more days after the fumigation
application, effectively prevents soil erosion (the rain and soil are
not in direct contact, and the tarp confines the soil preventing its
erosion and sediment transport) and acts to retard volatilization (such
that rapid soil degradation processes can take place). As mentioned
above, soil temperatures under tarps are significantly greater than
non-tarped fields, resulting in enhanced soil degradation. Therefore,
tarps not only prevent direct rain contact with treated soil,
eliminating the erosion and sediment movement effects, but also result
in considerably less chloropicrin being available for aquatic transport
once the tarps are removed. For broadcast applications of chloropicrin,
the tarps are in place for 5-7 days. For bedded applications, the tarps
are in place during the entire cropping cycle of the crop. For example,
on bedded strawberries, the tarp stays on the field from fumigant
application through the final harvest several months later.

EFED Comments:

EFED disagrees with the above modeling approach.  The modeling
assumptions used in Ritter (2007) do not accurately reflect subsurface
soil conditions and the fate of chloropicrin. The approach does not
account for subsurface hydrologic processes and sheet runoff during
rainfall events as chloropicrin can be diffused laterally as well as
vertically. Under saturated conditions, subsurface water containing
dissolved chloropicrin may migrate laterally from tarped fumigated field
to adjacent nontarped areas and may contribute to sheet runoff;
therefore, discounting rainfall events can underestimate exposure. The
contribution of lateral distribution [of the fumigant] to exposure can
be enhanced in raised-bed applications, where rainfall may accumulate in
areas between tarped raised beds and thereby contribute to sheet runoff.
 

CMTF’s Comment: (p. 63)

The Agency’s approach to handling the effect of tarps on chloropicrin
field runoff is not accurate. 

EFED Response: As indicated during the response to Phase 3 comments,
EFED acknowledges that there are some limitations in the capacity of
PRZM  to model fumigant exposure when tarps are used. These limitations
are discussed in the uncertainties section of the document. 

CMTF Response: (p. 63) Chemical Application Method (CAM=8)

This uncertainty also overestimates the EECs. PRZM/EXAMS do not appear
to be suited for modeling water transport of soil incorporated
fumigants. For example, none of the CAM inputs are representative of how
chloropicrin is applied to the field. The CAM input that is the most
similar to actual field applications is CAM=8, where the pesticide is
injected at 25 cm (10 inches deep) and is assumed to have uniform
distribution in the upper 25 cm of soil. However, it is unclear if the
CAM=8 input is capable of accounting for the downward diffusion of
chloropicrin in soil, which is a very real effect. If the PRZM/EXAMS
model assumes that the entire volume of applied chloropicrin is
distributed only in the upper 25 cm of soil, then this is clearly
inaccurate and it would result in exaggerated EECs. Chloropicrin
undergoes some downward diffusion. In fact, soil injection at 25 cm
ensures pest control down to a depth of 40+ cm in most soils and soil
conditions. Therefore, the CAM=8 assumption should be adjusted to
reflect that only about 50% of the applied chloropicrin would be
uniformly distributed in the upper 25 cm of soil and available for
transport.

EFED Response:

Research data ((Wang et al., 2005) and Ou et al., 2007) show that
injected fumigants generally concentrate in the shallow subsurface
layer. These data demonstrate that significantly higher MITC and
chloropicrin concentrations were concentrated in the upper 30 cm of the
tarped soil profile, and the effect lasted for about three days (Wang et
al., 2005). Ou et al. (2007) also confirmed that the concentrations of
chloropicrin and 1,3-D in the shallow subsurface (0.5 to 30 cm) soil
following shank injection becomes progressively more uniform and then
declines slowly. These results suggest that EFED’s use of CAM 8 and
uniform distribution of chloropicrin in the upper 25 cm for injection
depth of 10 inches for PRZM/EXAMS modeling are consistent with field
measurements. Since chloropicrin can be applied to a depth of 8 to 12
inches, the depth distributions of chloropicrin could be higher or lower
than the depth used for PRZM/EXAMS modeling. 

CMTF Comments: (p. 63) Distance from Field to Water Body: 

This is a fourth uncertainty that overestimates the EECs. The model
assumes that there is no distance between the treated field and the
water body receiving the runoff. This assumption is not in line with
reality since there would need to be at least 10 feet of space between
the field and pond, such as an access road that allows for the
maneuvering of tractors and other farm machinery. EFED should attempt to
account for a distance effect, with and without vegetative groundcover,
between the treated field and water body to generate a more realistic
and accurate risk assessment.

EFED Response:

The organic carbon partition coefficient (Koc) of chloropicrin is very
low and as such chloropicrin is not expected to sorb appreciably to
sediments.  Therefore, the contribution of runoff to surface water
bodies will be mainly in the form of solution phase of chloropicrin as
opposed to sediment-bound residues, i.e., erosion.   As such, buffer
areas between the fumigated field and adjacent water bodies will have
limited impact on EECs predicted by PRZM/EXAMS.

CMTF Comments: (p 63-64) Inflow, Dilution, and Outflow

 This uncertainty also overestimates the EECs. PRZM/EXAMS assume that
the runoff water does not add to the total volume of water in the pond,
i.e., EFED is unable to account for the dilution effect from the inflow
of runoff water. Given that the Pond is a relatively small body of water
(1 hectare x 2 m deep), the inflow of runoff that would accompany the
pesticide would dilute the EECs by some factor. For example, if it took
as little as one acre-inch of rain to induce a runoff event, then the
added water to the pond system would be over 670,000 gallons of water or
about a 12% increase in total volume. In reality, one acre-inch of water
is unlikely to produce runoff from any field, as this is a typical
irrigation rate for growers, and no runoff is experienced. One acre-inch
of water would have to fall in a very short period of time to induce
runoff, in which case, there would be very little opportunity for
chloropicrin to partition into the runoff water and the EECs would be
negligible. If it took two acre inches of water to induce runoff, then
the pond would increase by 25% in total volume. EFED should be able to
account for inflow water volume and the dilution effect it would have on
EECs since this would provide for a more accurate risk assessment. The
models also assume that, regardless of the inflow volume, at no time
does the pond experience outflow of water. By ignoring the effect these
errors have on the modeling results, EFED has overestimated.

EFED Response:

The above scenario may be applicable where rainfall exceeds evaporation
but under arid conditions such as in California, the 2-m deep pond
(i.e., standard pond evaluated in EXAMS) will not be able to maintain a
static volume because there is insufficient precipitation and runoff to
balance evaporation. As a result of evaporation, the volume in the pond
will be reduced resulting in higher concentrations than those predicted
by the static pond (EXAMS).  EXAMS is not intended to be a worst-case
scenario and is not conservative in comparison with other surface waters
such as vernal pools and/or wetlands where water volumes are less than
the pond scenario, turnover may be extremely limited, and evaporation
may serve to concentrate contaminants with time. EFED is developing a
variable volume pond scenario to reduce the uncertainty associated with
pond volume for aquatic exposure.

CMTF Comments: (p. 64)

The principle cause of this exaggerated soil metabolism value (15.71
days) is likely the use of the 10-day half-life value from
MRID#43613901. As EFED noted in its evaluation, this aerobic soil study
was conducted without supplying the system with continuous flow to
remove volatile materials. EFED also commented that this type of system
does not closely mimic field conditions where volatilized materials are
relatively free to escape. Essentially, in the study system, an unknown
amount of volatized

chloropicrin partitioned back into the soil phase, thereby resulting in
a half-life value (in

days) that is longer than would be expected under actual field
conditions. Therefore, the

10-day half-life value from this study should be considered upper bound.
Recalculating

the half-life value, by accounting for mass loss via volatilization and
system removal,

would result in a more accurate half-life value. 

EFED Response: The CMTF responded to several EPA questions (pp. 37-38 of
Comments on USEPA’s Chloropicrin Risk Assessment Phase 3, February 28,
2007; FRL: 8087-4; EPA-HQ-OPP-2006-0661). EFED reevaluated the half-life
for the study in question. Calculated half-lives are 4.4 days for the
total system and 3.7 days for soil. Recalculated half-life will be used
in PRZM/EXAM modeling for Phase VI of reregistration.  

CMTF Comments: (p. 65)

Other studies support an aerobic soil half-life value that is
considerably less than the 15.71 days EFED calculated or the 10 days as
calculated in MRID#43613901. For example, Gan et al. (2000) determined
the half-life values of chloropicrin at 20OC to be 1.5, 4.3, and 0.2
days in a sandy loam, loamy sand, and silt loam, respectively.

EFED response:

The above study (Gan et al., 2000) did not follow the Agency’s
Pesticide Assessment Guideline. Also, the study did not report whether a
trap was used to collect volatile chemicals, and material balance was
not reported. Based on the study limitations and incomplete material
balance, EFED can not confirm the estimated degradation half-lives for
various soil.  

CMTF Comment: (p. 66) Model Limitations: 

As discussed above, there are at least five major error-introducing
limitations in EFED’s current approach to modeling aquatic transport
of chloropicrin from treated fields. These are: (1) limited ability to
adequately characterize a volatile chemical and the effects of
temperature on volatilization and degradation rates; (2) limited ability
to adequately characterize the effects of tarping; (3) limited
suitability of the Chemical Application Method (CAM=8) to adequately
characterize fumigant soil distribution; (4) the assumption that the
treated field directly abuts the water body; and (5) the assumption that
the runoff water does not add to the water body volume nor does it
dilute the chemical concentration in the water body.

EFED Response: EFED provided rationales related to the above issues
cited by CMTF. EFED believes that PRZM and EXAMS models are adequate to
simulate exposure concentration for surface water bodies. EFED
acknowledged in the past that PRZM has limited capability to address
tarped applications. However, EFED also simulated PRZM/EXAMS to
determine EECs with lower application rate for non-tarped applications
in order to evaluate the level of concern (LOC) for aquatic organisms.
The LOC exceedances for aquatic organisms are very similar for both
tarped and untarped applications. Risk estimation and characterization
for both application scenarios will be provided in the revised
ecological risk assessment.  

CMTF Comment:

(p. 71) CMTF repeats its request for a waiver for chronic toxicity
studies with freshwater animal species.

EFED Response:

EFED’s aquatic modeling shows, for example, that 21-day average EECs
are 20 – 31% of peak EEC values (Table 8, 2008 revised assessment). 
There appears, therefore, to be a clear potential for chronic exposure
and effects. 

CMTF Comment:

(p. 72)  Estuarine environments have continual sharing of marine and
fresh waters (tidal

ebb and flow) and also continual or near continual tributary input from
the surrounding

terrestrial watersheds. Estuary and marine environments also have much
greater volumes

of water than the Pond scenario, and as such, any concentration effects
of chloropicrin in

a marine or estuarine environment would be negated almost
instantaneously via dilution

within the voluminous and usually turbulent marine or brackish water
bodies.

EFED Response:

EFED screening risk assessments use EECs from the standard EXAMS pond
model to assess potential risk to estuarine/marine organisms.  There are
many kinds of estuarine/marine habitats, including shallow salt marsh
areas that may even have lower water volumes than the standard pond
model.

CMTF Comment:

(p. 72) In order to equal or exceed the levels of concern for aquatic
plant acute risk (LOC

= 1) or the aquatic plant acute endangered species risk (LOC = 1), the
Toxicity Reference

Value would have to equal or exceed the peak EEC. Based on the revised
crop scenarios

and EECs, the CMTF believes that a waiver should be granted for aquatic
plant studies,

as the predicted peak EECs are very low. The highest peak EEC is
approximately 0.3175

ppb. This concentration is well below any likely acute toxicity value
for an aquatic plant

species. Given that EPA has previously acknowledged the limitations of
PRZM/EXAMS

for handling chloropicrin, in addition to its other shortcomings, even
these low EECs

should be considered worst-case scenarios and represent upper-bound
estimates. Based

on these issues, a waiver for any and all aquatic plant toxicity studies
is requested.

EFED Response:

For both terrestrial and aquatic plants, the LOC of 1 is met or exceeded
when the EEC (numerator) equals or exceeds the toxicity value used
(denominator).  The toxicity value used varies.  For aquatic plants, it
is the EC50 for the acute risk LOC and the EC05 or NOAEC for the acute
endangered species LOC.  Without aquatic plant toxicity data, it is not
known if these are exceeded.  Given chloropicrin’s broad spectrum of
toxicity, it is very conceivable that at least the acute endangered
species LOC could be exceeded, and perhaps the acute risk LOC as well. 

Revised Reregistration Risk Assessment  

Attached is the EFED Revised Reregistration Risk Assessment for
chloropicrin.  It has been revised based on 1) addition of PERFUM
modeling of air residues; 2) new aquatic toxicity data submitted; and 3)
new aquatic EECs, incorporating new environmental fate data submitted.

California Weather Data: Report

|   HYPERLINK "http://www.ipm.ucdavis.edu:/calludt.cgi/WXDATAREPORT" \l
"more#more"  About the data  |   HYPERLINK
"http://www.ipm.ucdavis.edu:/WEATHER/wxretrieve.html"  Weather menu  |

Daily averages report for FRESNO.A (CIMIS #80, Fresno State)

More about FRESNO.A:   HYPERLINK
"http://www.ipm.ucdavis.edu:/calludt.cgi/WXDESCRIPTION?MAP=&STN=FRESNO.A
"  Station description ; More data:   HYPERLINK
"http://www.ipm.ucdavis.edu:/calludt.cgi/WXSTATIONDATA?MAP=&STN=FRESNO.A
"  Daily  ~   HYPERLINK
"http://www.ipm.ucdavis.edu:/calludt.cgi/WXSTATIONAVG?MAP=&STN=FRESNO.A"
 Averages ; 

Time Period: January 1 to December 31, retrieved on April 9, 2008 (366
days)

DATE  PRECIP   AIR    SOLAR   SOIL   PAN 

      AMOUNT  TEMPS    RAD   TEMPS   EVAP

             MAX MIN        MAX MIN      

MM DD (IN)   (F)      (LY)  (F)      (IN)

----- ------ -------- ----- -------- ----

01-01  0.09   54  37   113   50  48

01-02  0.07   53  37   119   50  49

01-03  0.09   54  38   151   50  49

01-04  0.16   54  39   128   50  49

01-05  0.16   54  37   141   50  49

01-06  0.05   54  35   151   50  48

01-07  0.09   56  37   153   50  48

01-08  0.05   54  38   147   49  48

01-09  0.03   54  38   142   50  49

01-10  0.15   53  38   125   50  49

01-11  0.04   54  37   152   50  49

01-12  0.13   54  37   131   50  49

01-13  0.12   56  38   169   50  49

01-14  0.19   55  37   127   50  49

01-15  0.15   55  40   129   50  49

01-16  0.06   55  40   138   50  49

01-17  0.10   56  39   175   50  49

01-18  0.04   59  38   197   50  49

01-19  0.03   58  38   188   50  48

01-20  0.06   58  38   185   50  49

01-21  0.02   58  37   197   50  48

01-22  0.04   58  37   191   50  48

01-23  0.15   56  39   159   50  49

01-24  0.23   55  39   153   50  49

01-25  0.15   57  38   187   51  49

01-26  0.05   58  37   188   50  49

01-27  0.03   57  39   173   50  49

01-28  0.01   60  38   227   51  49

01-29  0.04   60  38   196   51  49

01-30  0.07   60  39   197   51  49

01-31  0.12   60  40   186   51  49

02-01  0.01   60  38   221   51  49

02-02  0.04   59  40   187   51  49

02-03  0.05   61  40   209   51  49

02-04  0.14   62  40   222   51  50

02-05  0.03   62  40   235   52  50

02-06  0.03   59  40   209   52  50

02-07  0.09   61  41   228   52  50

02-08  0.12   61  41   220   52  50

02-09  0.11   62  42   201   52  51

02-10  0.04   61  41   241   52  51

02-11  0.09   61  40   242   53  51

02-12  0.26   61  41   229   52  51

02-13  0.20   61  41   237   52  51

02-14  0.08   63  39   297   52  50

02-15  0.09   62  39   275   52  50

02-16  0.13   61  42   216   52  51

02-17  0.06   63  43   252   52  51

02-18  0.07   63  41   253   53  51

02-19  0.10   62  42   248   53  51

02-20  0.12   63  41   269   53  51

02-21  0.06   64  40   276   53  51

02-22  0.03   63  40   304   53  51

02-23  0.07   63  41   294   53  51

02-24  0.05   64  39   309   53  51

02-25  0.01   66  41   322   53  51

02-26  0.01   66  43   308   54  51

02-27  0.16   64  43   279   54  52

02-28  0.01   65  43   300   54  51

02-29  0.01   65  43   300   54  51

03-01  0.10   65  42   313   54  51

03-02  0.09   65  44   296   54  52

03-03  0.10   65  44   314   55  53

03-04  0.12   65  44   288   55  53

03-05  0.21   64  44   269   55  53

03-06  0.06   65  43   337   55  53

03-07  0.01   66  42   353   55  53

03-08  0.02   68  44   329   55  53

03-09  0.07   66  45   327   56  54

03-10  0.19   66  43   357   56  53

03-11  0.04   66  45   379   56  54

03-12  0.07   67  42   394   56  54

03-13  0.10   67  43   386   56  54

03-14  0.07   68  43   379   57  54

03-15  0.09   66  44   350   57  54

03-16  0.03   67  45   373   57  55

03-17  0.09   69  43   414   57  55

03-18  0.08   71  44   415   58  55

03-19  0.03   72  45   403   58  55

03-20  0.12   72  46   392   59  56

03-21  0.06   70  45   412   59  56

03-22  0.06   71  46   447   60  57

03-23  0.04   69  45   427   60  57

03-24  0.10   69  47   414   59  57

03-25  0.19   67  46   383   59  57

03-26  0.04   69  45   450   59  56

03-27  0.06   68  44   462   59  57

03-28  0.05   69  44   445   60  57

03-29  0.00   70  45   465   60  57

03-30  0.01   72  46   499   61  57

03-31  0.03   72  46   469   61  58

04-01  0.03   70  45   460   60  58

04-02  0.00   70  43   536   61  57

04-03  0.07   72  45   490   61  57

04-04  0.00   73  45   532   61  58

04-05  0.03   73  45   508   62  58

04-06  0.03   73  47   487   61  58

04-07  0.03   73  47   483   61  58

04-08  0.03   73  46   505   61  58

04-09  0.03   73  46   560   61  58

04-10  0.00   75  45   547   62  58

04-11  0.02   73  47   486   61  59

04-12  0.01   74  44   530   61  58

04-13  0.04   74  46   503   62  59

04-14  0.02   74  46   536   62  59

04-15  0.01   75  48   527   62  59

04-16  0.07   74  49   464   63  59

04-17  0.10   74  49   480   63  60

04-18  0.02   74  47   564   64  60

04-19  0.01   74  47   530   63  61

04-20  0.03   75  49   538   63  61

04-21  0.00   76  48   596   64  60

04-22  0.00   75  49   562   64  61

04-23  0.09   73  48   505   64  61

04-24  0.01   74  48   576   65  61

04-25  0.03   77  49   601   65  61

04-26  0.00   79  50   581   65  62

04-27  0.01   80  50   593   66  62

04-28  0.00   77  51   575   67  63

04-29  0.01   79  50   583   67  63

04-30  0.01   79  51   600   67  63

05-01  0.03   78  51   616   67  63

05-02  0.01   77  49   599   67  63

05-03  0.01   79  52   582   67  64

05-04  0.01   81  51   640   68  64

05-05  0.05   80  52   564   68  65

05-06  0.07   81  54   569   69  66

05-07  0.00   81  54   582   69  66

05-08  0.00   82  55   619   69  66

05-09  0.00   81  53   623   69  66

05-10  0.04   81  52   626   69  66

05-11  0.00   82  54   625   70  66

05-12  0.02   81  53   593   70  66

05-13  0.02   81  52   608   69  66

05-14  0.02   81  53   608   69  66

05-15  0.04   81  54   595   70  66

05-16  0.00   81  53   588   71  67

05-17  0.01   81  53   594   70  67

05-18  0.00   81  53   630   70  66

05-19  0.00   82  54   641   70  67

05-20  0.00   82  54   637   71  67

05-21  0.00   83  54   649   71  67

05-22  0.00   84  55   656   71  68

05-23  0.02   84  55   616   72  68

05-24  0.00   84  54   666   72  68

05-25  0.02   83  54   650   72  69

05-26  0.00   84  55   679   73  69

05-27  0.02   82  55   642   73  69

05-28  0.07   84  55   664   73  69

05-29  0.00   83  54   694   73  69

05-30  0.02   85  55   657   73  69

05-31  0.01   84  56   655   74  70

06-01  0.00   88  57   683   75  70

06-02  0.01   88  57   678   75  70

06-03  0.00   87  57   663   75  71

06-04  0.02   85  57   635   74  71

06-05  0.00   82  57   681   74  70

06-06  0.09   82  56   643   74  70

06-07  0.01   84  56   650   74  70

06-08  0.04   85  56   664   74  70

06-09  0.00   88  57   723   75  71

06-10  0.00   90  58   693   75  71

06-11  0.00   88  58   693   76  72

06-12  0.00   87  57   675   76  72

06-13  0.00   88  58   697   77  72

06-14  0.00   89  59   686   76  72

06-15  0.04   88  59   679   76  72

06-16  0.00   88  58   692   76  71

06-17  0.00   90  58   693   76  72

06-18  0.00   91  59   698   76  72

06-19  0.00   92  58   696   77  73

06-20  0.01   92  60   679   77  73

06-21  0.00   92  59   695   78  73

06-22  0.00   92  59   701   78  73

06-23  0.00   93  61   669   78  74

06-24  0.00   91  61   681   78  73

06-25  0.00   91  62   658   77  73

06-26  0.00   92  61   668   77  73

06-27  0.00   93  61   680   77  73

06-28  0.00   90  60   664   77  73

06-29  0.00   91  61   692   77  73

06-30  0.00   92  61   708   78  73

07-01  0.00   94  61   717   79  74

07-02  0.00   95  62   713   78  74

07-03  0.00   94  61   716   79  75

07-04  0.00   92  62   698   79  75

07-05  0.00   93  61   710   79  75

07-06  0.00   94  61   685   79  75

07-07  0.00   95  62   702   80  75

07-08  0.00   96  64   680   80  76

07-09  0.00   95  64   687   80  76

07-10  0.00   94  63   698   80  76

07-11  0.00   94  63   674   80  76

07-12  0.00   94  63   679   80  76

07-13  0.00   96  64   688   80  76

07-14  0.00   96  65   689   81  77

07-15  0.00   95  64   694   80  77

07-16  0.00   93  62   670   80  76

07-17  0.00   92  62   680   79  76

07-18  0.00   94  62   691   79  76

07-19  0.00   94  63   678   79  76

07-20  0.00   93  63   669   79  76

07-21  0.00   93  63   639   79  75

07-22  0.00   94  64   631   79  75

07-23  0.00   94  64   643   79  76

07-24  0.00   94  62   674   79  76

07-25  0.00   95  62   674   79  75

07-26  0.00   96  63   669   79  76

07-27  0.00   97  63   664   79  76

07-28  0.00   98  63   658   79  76

07-29  0.00   96  62   656   79  75

07-30  0.00   95  63   655   79  76

07-31  0.00   95  62   649   79  75

08-01  0.00   97  63   657   79  75

08-02  0.00   97  63   650   79  76

08-03  0.00   96  64   631   79  76

08-04  0.00   97  64   643   79  76

08-05  0.00   97  64   641   79  76

08-06  0.00   96  64   626   80  76

08-07  0.00   96  63   613   80  77

08-08  0.00   96  64   612   80  77

08-09  0.00   97  64   621   79  76

08-10  0.00   95  64   620   79  77

08-11  0.00   94  63   617   80  76

08-12  0.00   95  64   601   80  76

08-13  0.00   95  63   617   80  76

08-14  0.00   94  63   595   80  76

08-15  0.00   94  62   617   80  76

08-16  0.00   94  61   623   79  75

08-17  0.00   94  61   609   78  74

08-18  0.00   92  60   588   79  74

08-19  0.00   93  60   596   78  74

08-20  0.00   92  61   573   78  75

08-21  0.00   92  60   603   78  75

08-22  0.00   93  60   600   78  75

08-23  0.00   94  61   589   78  75

08-24  0.00   95  60   587   78  75

08-25  0.00   94  61   576   78  74

08-26  0.00   94  61   560   78  74

08-27  0.00   94  62   577   78  74

08-28  0.00   94  62   572   78  75

08-29  0.00   94  61   555   78  75

08-30  0.00   92  60   565   78  75

08-31  0.00   93  60   556   78  74

09-01  0.01   93  61   540   78  74

09-02  0.00   93  63   496   78  75

09-03  0.00   93  62   538   77  74

09-04  0.00   92  62   519   77  74

09-05  0.00   93  61   539   77  74

09-06  0.00   93  60   531   77  74

09-07  0.00   93  59   538   77  74

09-08  0.00   94  59   528   77  73

09-09  0.00   90  58   514   77  73

09-10  0.00   88  56   525   76  72

09-11  0.00   87  57   509   76  73

09-12  0.00   87  56   503   76  72

09-13  0.00   89  57   499   75  71

09-14  0.00   89  57   506   75  71

09-15  0.00   89  57   501   75  72

09-16  0.01   88  56   465   75  72

09-17  0.02   86  56   454   74  71

09-18  0.02   86  57   452   74  71

09-19  0.00   88  56   479   74  71

09-20  0.00   88  56   490   74  71

09-21  0.00   89  57   471   74  71

09-22  0.00   88  57   455   74  71

09-23  0.00   88  57   435   73  71

09-24  0.02   87  57   446   73  71

09-25  0.01   85  57   432   73  71

09-26  0.01   86  55   445   73  71

09-27  0.01   85  56   440   73  70

09-28  0.01   85  56   420   73  70

09-29  0.01   88  55   447   73  70

09-30  0.00   89  56   450   73  70

10-01  0.00   88  56   432   73  70

10-02  0.00   86  55   432   73  70

10-03  0.00   86  55   431   72  69

10-04  0.05   84  53   408   72  69

10-05  0.01   84  53   415   72  68

10-06  0.00   84  53   416   71  68

10-07  0.00   84  51   414   71  68

10-08  0.00   85  51   413   71  68

10-09  0.01   85  52   398   71  67

10-10  0.06   85  52   383   70  67

10-11  0.03   81  52   372   70  67

10-12  0.00   80  50   366   69  67

10-13  0.00   80  49   379   68  66

10-14  0.00   81  50   370   68  66

10-15  0.00   81  50   376   68  65

10-16  0.00   80  49   365   68  65

10-17  0.00   80  48   365   67  65

10-18  0.00   80  48   357   67  64

10-19  0.00   80  48   353   67  64

10-20  0.01   80  46   356   67  64

10-21  0.02   79  49   319   67  64

10-22  0.02   78  47   333   66  64

10-23  0.00   79  48   336   66  64

10-24  0.03   76  47   294   66  63

10-25  0.00   75  46   314   66  63

10-26  0.08   76  47   294   65  62

10-27  0.02   75  46   304   65  62

10-28  0.04   72  46   268   64  62

10-29  0.14   71  47   257   64  61

10-30  0.06   71  44   277   63  61

10-31  0.01   71  45   275   63  61

11-01  0.01   71  44   292   63  60

11-02  0.00   71  42   293   62  60

11-03  0.00   72  42   302   62  59

11-04  0.00   72  42   273   61  59

11-05  0.00   74  44   274   62  59

11-06  0.00   71  43   276   61  59

11-07  0.02   68  42   244   61  59

11-08  0.01   70  42   272   61  59

11-09  0.02   69  42   260   61  58

11-10  0.08   68  43   221   60  59

11-11  0.07   69  43   244   60  58

11-12  0.07   69  41   247   60  58

11-13  0.07   67  42   212   60  58

11-14  0.02   65  40   242   60  57

11-15  0.03   63  39   216   59  57

11-16  0.03   64  39   218   58  57

11-17  0.11   64  41   203   58  57

11-18  0.00   64  40   213   58  56

11-19  0.03   65  41   209   58  56

11-20  0.01   65  39   206   58  56

11-21  0.05   62  40   178   58  56

11-22  0.02   63  41   188   58  56

11-23  0.02   63  39   216   57  56

11-24  0.04   63  38   210   57  55

11-25  0.09   60  39   155   57  55

11-26  0.06   60  37   200   56  55

11-27  0.00   60  37   197   56  54

11-28  0.01   59  36   168   55  54

11-29  0.03   62  37   190   55  54

11-30  0.03   61  37   205   55  53

12-01  0.02   60  37   186   55  53

12-02  0.00   61  36   195   54  53

12-03  0.02   61  36   190   55  53

12-04  0.02   59  38   172   54  52

12-05  0.09   58  39   142   54  53

12-06  0.06   59  40   152   54  53

12-07  0.08   58  39   160   54  53

12-08  0.01   60  36   185   54  52

12-09  0.07   57  38   155   54  52

12-10  0.08   57  39   146   54  52

12-11  0.09   56  38   128   53  52

12-12  0.04   55  37   157   53  52

12-13  0.03   56  36   171   53  51

12-14  0.07   54  35   133   52  51

12-15  0.03   53  35   143   52  51

12-16  0.06   53  35   145   52  50

12-17  0.02   54  36   127   51  50

12-18  0.02   55  36   144   52  50

12-19  0.05   51  35   122   51  50

12-20  0.11   52  34   145   51  50

12-21  0.01   50  33   143   51  49

12-22  0.06   50  33   128   51  49

12-23  0.01   50  32   147   50  49

12-24  0.06   51  32   166   50  49

12-25  0.01   51  32   164   50  49

12-26  0.02   54  32   163   50  48

12-27  0.02   56  33   175   50  48

12-28  0.06   55  35   143   50  48

12-29  0.16   53  36   125   50  49

12-30  0.09   56  37   154   50  49

12-31  0.01   57  37   155   50  48

366 records listed

	

Measurement details about FRESNO.A variables:

Air temperature: Daily max/min measured at 1.5 m (4.92 ft).

Precipitation: Daily total measured in a 20 cm (8 in) diameter gauge.

Soil temperature: Daily max/min measured at a 15 cm (6 in) depth.

Humidity: Daily max/min relative humidity measured at 1.5 m (4.92 ft).

Evapotranspiration: Calculated from CIMIS hourly values.

Solar radiation: Daily global radiation measured by Licor pyranometer at
2 m (6.5 ft).

Wind speed & direction: Daily average measured at 2 m (6.5 ft).

   HYPERLINK "http://www.ipm.ucdavis.edu/WEATHER/abtwxreports.html" 
http://www.ipm.ucdavis.edu/WEATHER/abtwxreports.html 

 Wang,  D., J. Juzwik, and S.Fraedrich. 2005. Emission and soil
distribution of fumigants in forest tree nurseries. 2005 Annual
International Research Conference on Methyl Bromide Alternatives and
Emissions Reductions. 

 Ou L., J. Thomas, L. Allen, J. Vu and D. Dickson. 2007. Effects of
injection systems and plastic mulches on distribution and emissions of
cis- and trans- 1,3-Dichloropropene and chloropicrin. Arch. Environ
Contam Toxicol. 53: 141-150

 http://www.epa.gov/scipoly/sap/meetings/2004/033004_mtg.htm

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