UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

OFFICE  OF 

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

February 23, 2006     

PC Code 081501

DP Barcode(s): D305331

MEMORANDUM

			

SUBJECT:		Revised draft of Environmental Fate and Ecological Risk
Assessment of Chloropicrin following the review  of 30-day  Error
Correction Comments

TO:			Nathan Mottl, Risk Manager Reviewer

			Susan Lewis, Risk Manager

			Special Review and Reregistration Division (7508C)

FROM:		Faruque Khan, Environmental Scientist

			James Felkel, Wildlife Biologist	

			Environmental Risk Branch V

			Environmental Fate and Effects Division (7507C)

APPROVED BY:	Jean Holmes, Acting Branch Chief

			Environmental Risk Branch V

			Environmental Fate and Effects Division (7507C)

The attached document is the Environmental Fate and Effects Division
(EFED) revised  screening-level risk assessment in support of the
Reregistration Eligibility Decision of chloropicrin.   Revisions include
an update on ecological incidents.

The Environmental Fate and Effects Division (EFED) has completed its
review of comments received from the Chloropicrin Manufacturers’ Task
Force (CMTF) on the EFED September, 2005 draft environmental fate and
ecological risk assessment.  Many of the comments received from the CMTF
represent their interpretation related to exposure models or scenarios
used in EFED’s assessment and do not pertain to actual errors. The
EFED risk assessment has been  conducted in general accordance with the
Agency guidance on ecological risk assessment and the OPP ecological
risk assessment Overview document.  Since the intent of the initial
30-Day comment period is to simply correct obvious errors (e.g.
calculation errors) in the chapter, issues beyond this will be
considered along with future public comments in the Phase III review
process.

The focus of this risk assessment is on the pre-plant soil fumigant use
of chloropicrin, used to control a broad range of soil pathogens. 
Chloropicrin is typically applied as a liquid once per growing season
through soil injection or drip irrigation to fumigate the upper six to
twelve inches of soil 14 days or more before planting. The maximum
application rate is 350 lbs a.i./Acre, with 300 lbs a.i./Acre the
maximum for drip irrigation. The Problem Formulation, Analysis, Risk
Characterization, and Executive Summary for this assessment can be found
in the attached document.  

Outstanding Data Requirements and Data Gaps  

Environmental Fate:

The environmental fate data base for the parent compound provided mostly
supplemental information (Table 1A-B). Key environmental fate studies
such as aerobic soil metabolism and photolysis in air have several
deficiencies and problems. Data related to these key environmental fate
processes were also obtained from open literature to complete the
environmental fate and exposure assessment. However, no additional
environmental fate data for Chloropicrin are required at this time.

 

Ecological Effects: 

The following data are needed on chloropicrin for ecological risk
assessment.  These data needs are similar to those available or
previously specified as needed for risk assessment for methyl bromide
and for the degradate MITC as part of the metam-sodium risk assessment. 
Table 1A-A  lists the status of the ecological effects data requirements
for chloropicrin. 

71-1 Avian Acute Oral.  The current estimate of avian risk is based
largely on the mammal assessment.  This basic study will contribute to a
risk assessment specific to birds.  It will 1) enable a comparison to
the mammal acute oral data and 2) enable the use of an EFED spreadsheet
to estimate avian acute inhalation toxicity based on the mammal acute
oral and inhalation data.

----- Avian acute inhalation.  The current estimate of avian risk is
based largely on the mammal assessment.  This study will enable an
inhalation risk assessment specific to birds.  Since the risk assessment
for terrestrial wildlife is focused on inhalation and this study will
provide actual inhalation data rather than an estimation based on acute
oral data, it is of even higher priority than the acute oral study.

-----Avian sub-chronic/chronic inhalation.  This study is needed for
risk assessment, due to the potential for repeat and/or continuous
exposure to birds resulting from  the use of chloropicrin on multiple
fields over multiple days in any given geographic area.

870.1300.  Acute inhalation toxicity test – rat..  The existing study
(MRID 45117902) is classified by HED as Acceptable/Non-guideline.  The
7/25/00 DER and 1/31/05 Revised HED Human Health Risk Assessment state:
“The LC50 calculated for the study should not be considered to be a
true LC50 for chloropicrin.  Due to the sacrifice of all live animals at
day 3 of the study instead of day 14, and too large of exposure particle
sizes, the true LC50 could be lower.”  Thus, a new study will enable
an improved wild mammal risk assessment with reduced uncertainty. 
Please note that although EFED needs the results this study for risk
assessment, it is not listed in Appendix E since it is an HED guideline
and EFED does not review these studies.

72-1(a) and (c) Acute Fish Toxicity – bluegill and rainbow trout.  The
risk assessment is currently relying on supplemental data, with
indeterminate toxicity values.  Flow-through studies with measured
concentrations will greatly reduce uncertainty.

72-2(a) Acute aquatic invertebrate toxicity.  The risk assessment is
currently relying on supplemental data, with indeterminate toxicity
values.  Flow-through studies with measured concentrations will greatly
reduce uncertainty.

72-3(a) Acute Marine/Estuarine Fish. Given the use patterns of
chloropicrin, marine/estuarine species could be exposed.  This study
will enable a risk assessment specific for marine/estuarine species
exposure.

72-3(b) Acute Marine/Estuarine Mollusk.  Given the use patterns of
chloropicrin, marine/estuarine species could be exposed.  This study
will enable a risk assessment specific for marine/estuarine species
exposure.  It will also improve certainty with the endangered species
risk assessment, as this test species may be more representative of
endangered freshwater mussels than the freshwater Daphnia.

72-3 (c) Acute Marine/Estuarine Shrimp. Given the use patterns of
chloropicrin, marine/estuarine species could be exposed.  This study
will enable a risk assessment specific for marine/estuarine species
exposure.  One literature search toxicity value is available, but it is
from a static study without measured concentrations.

72-4(a) Early Life-stage Fish – Freshwater.  Current aquatic modeling
indicates the potential for chronic aquatic exposure to chloropicrin.
This study will enable a chronic risk assessment for freshwater fish.

72-4(a) Early Life-stage Fish – Marine/Estuarine.  Current aquatic
modeling indicates the potential for chronic aquatic exposure to
chloropicrin.  This study is reserved pending the submission and review
of the above early life-stage studies with a freshwater fish species.

72-4(b) Life-Cycle Aquatic Invertebrate.  Current aquatic modeling
indicates the potential for chronic aquatic exposure to chloropicrin. 
This study will enable a chronic risk assessment for aquatic
invertebrates.

 

72-5 Life-Cycle Fish. This study is reserved, pending submission and
review of early life-stage fish testing.

123-1(a) Seed Germination/Seedling Emergence – Tier II.  Chloropicrin
is used in part due to its phytotoxicity  at the application site, and a
wide range of open literature and other non-guideline studies indicate
the potential for plant damage.  This study will enable the assessment
of risk to non-target terrestrial plants off-site.

123-1(b) Vegetative Vigor – Tier II.  Chloropicrin has at least some
phytotoxicity on the treatment site, based on label and open literature
information.  This study will enable the assessment of risk to
non-target terrestrial plants off-site.

123-2 Aquatic Plant Growth – Tier II.   Chloropicrin has at least some
phytotoxicity on the treatment site, based on label and open literature
information.  This study will enable the assessment of risk to
non-target aquatic plants off-site. 

141-1 Honeybee Acute contact.  This basic study is now being requested
for virtually all outdoor uses, and will help determine the need for,
and specifics of, bee hazard labeling.

Uncertainties

Environmental Fate:

	There are uncertainties in estimating chloropicrin exposure in surface
water from post-application, due to tarping of the treated area.  If
tarping is used to minimize the volatilization of chloropicrin, the
loading of the chemical through runoff will be limited until the tarp is
sliced or removed from the field. The present version of the PRZM model,
as well as the selected crop scenarios,  has limited capabilities in
discounting the load from runoff of applied chemical under a
post-application tarp scenario. PRZM also has limited capabilities in
capturing the partitions of a volatile chemical in air, water and
sediment. Since the load of chloropicrin from runoff is considered in
the PRZM/EXAMS simulation, the estimated concentrations of chloropicrin
in surface water bodies may be upper bound. 

	There are uncertainties with both existing monitoring and modeling of
air residues for the purpose of estimating exposure to terrestrial
wildlife.  Since field emission and air  monitoring data of chloropicrin
were collected greater than 1 meter above the ground surface, actual
concentrations at ground level may differ from estimated air
concentration using ISCTS3 modeling and ambient air monitoring . Air
monitoring at ground-level of chloropicrin in the fumigated fields may
reduce the uncertainty related to terrestrial exposure for wildlife.

Ecological Effects: 

	There are substantial uncertainties concerning the ecological effects
of chloropicrin, in part due to the extremely limited data available for
risk assessment.  There are no studies considered fully acceptable for
any taxonomic group or time exposure, except for the mammal acute oral
and chronic inhalation data used. 

	The uncertainties associated with the risk to terrestrial organisms
from chloropicrin use  are mainly focused on the extent and effect of
terrestrial animal exposure via inhalation.  There is uncertainty with
the mammal acute inhalation toxicity, as indicated above.  Avian
inhalation toxicity data are not available at all, as also noted.  In
addition, the lack of avian acute oral data prevents an extrapolated
estimation of inhalation toxicity based on mammal data.  Terrestrial
plant data are needed to conduct an assessment of risk to non-target
terrestrial plants off-site.

	Because of the repeat exposures from applications to different fields
on different days in a given geographic area, there is the added
potential for chronic exposure.   Acute inhalation studies are typically
just 4 hours long.  A subchronic/chronic avian inhalation study will
enable EFED to address longer-term exposure to birds.

	The uncertainties associated with the risk to aquatic organisms from
chloropicrin are due to uncertainties over the length of exposure to
this highly volatile chemical and to uncertainties over the toxicity
(resulting mainly from the volatility).   However, both acute and
chronic exposure are possible, in part due to repeat or continuous input
to the aquatic environment.  Acute and chronic toxicity data  are not
available for most fish and aquatic invertebrate guideline test
categories, freshwater or estuarine/marine.   The risk assessment relies
on supplemental data for freshwater fish and aquatic invertebrates. 

EFED Label Recommendations

	i. Manufacturing Use Product:

	This pesticide is toxic to mammals, birds, fish, and aquatic
invertebrates.  Additionally, because it is a broad spectrum fumigant,
it is presumed to also be toxic to additional organisms, including
beneficial insects, amphibians, and reptiles.  Do not discharge effluent
containing this product into lakes, streams, ponds, estuaries, oceans,
or other waters unless in accordance with the requirements of a National
Pollutant Discharge Elimination System (NPDES) permit and the permitting
authority has been notified in writing prior to discharge.  Do not
discharge effluent containing this product to sewer systems without
previously notifying the local sewage treatment plant authority.  For
guidance, contact your State Water Board or Regional Office of the EPA. 


	ii. End Use Products

	This pesticide is toxic to mammals, birds, fish, and aquatic
invertebrates.  Additionally, because it is a broad spectrum fumigant,
it is presumed to also be toxic to additional organisms, including
beneficial insects, amphibians, and reptiles.  Do not apply directly to
water, or to areas where surface water is present or to intertidal areas
below the mean high water mark.   Do not contaminate water when
disposing of equipment washwater or rinsate.  Drift and runoff may be
hazardous to aquatic organisms in water adjacent to treated areas.

	iii. Surface and Ground Water Advisory		

	

	Do not slice or remove the tarp, if it is raining or if rain is
expected within 48 hours. Since chloropicrin is very soluble, rain could
cause chloropicrin  remaining under the tarp to contaminate ground water
through leaching and surface water through runoff.	

Table 1A (A). Ecological Effects Data Requirements for: Chloropicrin   
                                  



Guideline #	

Data Requirement	Are Additional Data Needed for Risk Assessment?	

MRID #’s	Study Classification



  71-1(a)	Avian Acute Oral	Y	------------	------------

------	Avian Acute Inhalation	Y	------------	-----------

71-2(a)	Avian Dietary–quail	N	------------	------------

71-2(b)	Avian Dietary–mallard	N	------------	-------------

---------	Avian Subchronic/Chronic Inhalation 	Y	-------------
-------------

72-1(a)	Fish Acute Toxicity–bluegill	Y	FTLR 439	S

72-1(b)	Fish Acute Toxicity–rainbow trout	Y	FTLR 425	S

72-2(a)	Aquatic Invertebrate Acute Toxicity–freshwater	Y	130704	S

72-3(a)	Marine/Estuarine Acute Toxicity–Fish	Y	-------------
-------------

72-3(b)	Marine/Estuarine Acute Toxicity–Mollusk (shell deposition)	Y
------------

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



72-3(c)	Marine/Estuarine Acute Toxicity–Shrimp	Y	------------
-------------

72-4(a)	Fish Early Life Stage–freshwater	Y	-------------	-------------

72-4(a)	Fish Early Life Stage– marine/estuarine	Reserved	------------
-------------

72-4(b)	Aquatic Invertebrate Life Cycle–freshwater 	Y	-----------
------------

123-1(a)	Seedling Germination/Seedling Emergence–Tier II 	Y
-------------	------------

123-1(b)	Vegetative Vigor–Tier II 	Y	-------------	------------

123-2	Aquatic Plant Growth – Tier II	Y

-----------

141-1	Honeybee Acute Contact 	Y	-------------	------------

A=Acceptable; S=Supplemental; U=Unnaceptable; W=Waived; N/A=Not
Applicable; NA=Not Available; Inv.=Invalid; R=Potentially Repairable





Table 1A (B). Environmental Fate Data Requirements for: Chloropicrin





Guideline #	

Data Requirement	Is Data Requirement Satisfied?	

MRID #’s	Study Classification



161-1	Hydrolysis	Y	43022401	A

161-2	Photodegradation in Water	Y	42900201	S

161-3	Photodegradation on Soil	N/A	NA	W

161-4	Photodegradation in Air	Y	05007865	A

162-1	Aerobic Soil Metabolism	Y	43613901	S

162-2	Anaerobic Soil Metabolism	N/A	----------	----------

162-3	Anaerobic Aquatic Metabolism	Y	43759301	S

162-4	Aerobic Aquatic Metabolism	N/A	----------	----------

163-1	Mobility-Column Leaching	Y	44191301	S

163-2	Laboratory Volatility	Y	43798601	A

163-3	Field Volatility	Reserved	----------	----------

164-1	Terrestrial Field Dissipation	N	43085101	S

165-4	Accumulation in Fish/

Bioconcentration	N/A	NA	W

A=Acceptable; S=Supplemental; U=Unnaceptable; W=Waived; N/A=Not
Applicable; NA=Not Available



