Document ID: EPA-HQ-OPP-2007-0626-0002
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-01-23T05:00Z

Interregional Research Project Number 4 (IR-4)

PPs (2E6424, 2E6481, 3E6585, 3E6544)

EPA has received pesticide petitions from OR-CAL Inc, 29454 Meadowview
Rd., Junction City, OR 97448 on behalf of  IR-4, 500 College Road East,
Suite 201W, Princeton, NJ 08540, proposing pursuant  to Section 408(d)
of the Federal Food, Drug, and Cosmetic Acid, 21 U.S.C. 346a(d), to
amend 40 CFR Part 180 by establishing tolerances for residues of
Metaldehyde, in or on the Berry  Group 13; lingonberry; juneberry; and
salal at 0.1  parts per million (ppm), artichoke at 0.05 ppm, cactus,
prickly pear at 0.1 ppm, and watercress at 2.0 ppm.  Lonza Inc. is the
primary source of technical Metaldehyde.  OR-CAL, Inc. prepared and
summarized the following information in support of the pesticide
petitions for Metaldehyde. EPA has determined that the petitions contain
data or information regarding the elements set forth in section
408(d)(2) of the FFDCA. However, EPA has not fully evaluated the
sufficiency of the submitted data at this time or whether the data
support granting of the petitions.  Additional data may be needed before
EPA rules on the petitions. 

Residue Chemistry

          

     1.   Plant Metabolism. Translocation studies using 14C-Metaldehyde
have been conducted in leaf lettuce and sugar beets (MRIDs 43923301 and
43923302). The objective of these studies was to determine if
Metaldehyde would translocate into the leaves of lettuce plants and
foliage and roots of beets plants under experimental conditions
simulating a worse-case field situation. The nature of the 14C-residues
also was investigated. A single application of a liquid formulation
amended with 14C-Metaldehyde was made to soil 18 days after beet seeds
were planted and 38 days after lettuce seeds were planted. The
formulation contained 4% Metaldehyde and was applied at an exaggerated
application rate which represented approximately 14 times the maximum
label use rate, i.e. 13.76 pounds (active ingredient) per acre. 

Following application of the test substance, the plants were maintained
according to standard agricultural practices until the time of harvest,
which took place 28 days following treatment for lettuce and 42 days
following treatment for beets. Lettuce (inner and outer leaves) and
beets (foliage and roots) were harvested and stored frozen. The samples
were homogenized and total radioactive residue (TRR) in each sample was
determined by combustion and subsequent liquid scintillation counting
(LSC) analysis. In addition, treated lettuce and beet samples ere
extracted with methylene chloride (DCM), concentrated and analyzed using
reverse-phase high performance liquid chromatography (HPLC) in order to
determine the nature of the radioactive residue. Prior to the analytical
phase of the study, the extraction method and the HPLC system used were
successfully validated to extract 100% of Metaldehyde in the sample and
to detect it at an LOQ of 5 ppb and 8 ppb in lettuce.

LSC analysis of the lettuce from the treated lettuce plot showed that
the lettuce contained an average TRR level (expressed as 14C-Metaldehyde
equivalents) of 2.44 ppm from the outer leaves and 2.36 ppm from the
inner leaves. The corresponding values for the beet foliage and roots
were 2.87 and 0.61 ppm, respectively. The average LOQ for combustion
radioassay of the control lettuce and beet samples was < 5 ppb. HPLC
analysis of treated lettuce and beet samples showed that 100% of the
radioactivity in the lettuce and beet samples consisted of parent
14C-Metaldehyde.

On the basis of these studies, the Agency determined that the only
residue of concern was parent compound and granted waivers from
conducting full guideline nature of the residue studies in plants with
Metaldehyde.

2. Analytical Method-Blueberry

Preparation. The samples were received frozen and in good condition at
the Food and Environmental Toxicology Laboratory, University of Florida,
Gainesville, on the following dates: 7/17/00 (North Carolina samples),
7/27/00 (Oregon samples), 8/7/00 (samples from the terminated New Jersey
trial), 9/29/00 (Michigan samples), 7/17/01 (North Carolina samples),
and 8/21/01 (New Jersey samples). The samples were logged in and stored
in a freezer at temperatures generally in the range  -36° to -6°C. On
3/1/01, the air temperature in the freezer rose to +5°C for
approximately 40 minutes as a result of opening the freezer door for
sample inventory. The samples remained frozen at all times and there was
no adverse impact on the study.

Methods. The samples were analyzed using a modification of the reference
method: Analytical method for the determination of Metaldehyde in
lettuce by GC/MS. ENC-3/99. EN-CAS Analytical Laboratories. The
modifications are listed under the Procedure section. Analytical
reference standards of Metaldehyde were received from two
sources-1)Aldrich, lot# 06301HN, 98% pure, received 2/9/00, and 2) Acros
Organic, lot# A005047103, 99% pure, received 1/10/01. Expiration dates
had not been assigned to these standards by the respective suppliers, so
the laboratory personnel assigned dates two years from the dates of
receipt. The Limit of Quantitation (LOQ) was established at 0.03 ppm.
The Limit of Detection (LOD) was established at 0.01 ppm. 

Preparation of samples. Frozen samples were processed by chopping with
dry ice in a Hobart food processor. The chopped samples were then place
in the freezer to allow the dry ice to sublime completely.
Representative subsamples were subsequently weighed (15 g or 25 g for
storage fortification) into screw capped 1 pint mason jars and returned
to freezer storage until analysis. Alphabetical letters were used to
designate replicates of subsamples (e.g. 200288A, 200288B).

Sample chopping dates:

Trial ID		Date

00-MI03		10/25/00

00-MI04		10/25/00

00-NC11		08/03/00

00-NC12		08/03/00

00-OR12		08/13/00

01-NC26		08/14/01

01-NJ34		08/23/01

The samples were fortified by adding 1 mL of each fortification solution
to untreated subsamples to yield the required fortification levels. For
example, 1 mL of 0.75 µg/mL solution was added to 15 g control
subsample to obtain a fortification level of 0.05 ppm.

The recovery samples were fortified prior to the addition of the
extraction solvent. 

Six control subsamples (25 g each) from the 00-NC 12 trail were
fortified at the 1 ppm on 08/15/00 and then returned to the freezer with
the field samples. 

Procedure. (This procedure is a modification of the method as referenced
under the Method section).

Extraction: To a 15 g chopped subsample in a Mason jar (25 g for the
storage study samples), 150 mL of dichloromethane and 50 g of sodium
sulfate were added. The sample jar was then placed on an Eberbach
horizontal platform shaker and shaken for one hour.

Filtration and Evaporation: The entire sample was filtered through a 50
g pad of anhydrous sodium sulfate (pre-washed with dichloromethane) on
top of a glass wool plug, into a 250 mL Erlenmeyer flask. The Mason jar
and the sodium sulfate pad were rinsed with 25 mL methylene chloride and
the rinsate was combined with the filtrate.

The entire filtrate was quantitatively transferred to a graduate
cylinder and measured. 

One half the amount was evaporated to approximately 1-5mL using a
turboVap with a water bath temperature below 30°C.

The solution was adjusted to an appropriate volume with dichloromethane
for GC/MS analysis.

All final sample extracts were stored in a laboratory grade freezer at
temperatures ranging from -31°C to -17°C if not analyzed immediately
after extraction.

Recoveries. Blueberry samples were fortified with Metaldehyde at
approximately 0.05 ppm and 1 ppm in order to validate the method.
Recoveries were in the respective ranges of 83-91% and 82-92%.
Concurrent recoveries were conducted at the same levels, with results of
80-103% at 0.05 ppm and 79% at 1 ppm. 

3.    Magnitude of the Residue- Blueberry

Six blueberry trials were scheduled in 2000 to develop data in support
of the reregistration of Metaldehyde on berries. There trials were
conducted in Michigan (2 trials), North Carolina (2 trials), New Jersey,
and Oregon. The New Jersey trial was terminated following the completion
of the trial when it was determined that the test substance had been
under-applied by approximately 90%. Two additional trials were conducted
in 2001, one in New Jersey and one in North Carolina. The North Carolina
trial was added because the two trials in that state that had been
conducted in 2000 did not meet protocol requirements for trial
differentiation (the plots in the two trials were on the same soil
series and had the same blueberry cultivar, and the last four
applications in both trials were made on the same dates).  In each trial
except the successful New Jersey trial, applications were made using a
shaker container with a single aperture. In the New Jersey trial, the
applications were made by hand from a beaker containing the test
substance. Deadline®M-P’s (4% Metaldehyde active ingredient) were
applied to the wet or moist soil in a line on each side of the crop, 1-3
feet from the base of the plants. The protocol required that 0.8 lb
ai/acre be applied to the soil in the treated plot. The labeled
concentration of the formulated test substance was 4%; however, the
Certificate of Analysis for the test substance states that the purity
was determined to be 4.27 ± 0.14%. As a result, the actual amount of
active ingredient applied per application was 0.854 lb ai/acre. Five
applications were made in each trial, with a re-treatment interval of 14
days.  Treated and untreated samples were collected on the day of the
last application. The samples were held in frozen storage until delivery
to the analytical laboratory via Federal Express (Oregon trial) or ACDS
freezer truck (all other trials). 

Storage stability. Bluberry samples were fortified with Metaldehyde at
0.988 ppm and stored frozen for 273 days. Metaldehyde was recovered at
92%, 84%, and 90% of the original spike level, thus demonstrating the
stability of the compound after frozen storage for nine months. 

Results. Although no residues of Metaldehyde were detected at or above
the calculated LOQ ( 0.03 ppm) in any of the samples, all samples
residue results were reported at less than 0.05 ppm, LLMV, as method
validation was not performed at the 0.03 ppm level. 

Both fortified and unfortified control samples were analyzed
concurrently with each sample set to demonstrate the absence of
interferences and adequate recovery. The concurrent recoveries at 0.05
ppm ranged from 80% to 103% (average=87%, sd=9, n=6).

The reported residue results were not corrected for recovery(s). 

4. Analytical Method-Raspberry

Preparation. The samples were received frozen and intact at the North
Central Region Leader Laboratory, Michigan State University, East
Lansing, on 7/12/00 (Oregon trials) and 8/8/00 (Washington trial). The
samples were logged in and stored frozen at  -27° to -13°C until
extraction and analysis. 

Method. The samples were analyzed using a modification of the referenced
method: Analytical method for the determination of Metaldehyde in
lettuce by GC/MS. ENC-3/99. EN-CAS Analytical Laboratories. The
modification is listed on page 3 of this Notice of Filing under the
Procedure section. The Metaldehyde analytical reference standard (lot #
A005047103, 99.4% pure, expiration date 1/12/02) was received on 1/12/00
from Acros Organics of Fair Lawn, N.J. The Limit of Quantitation (LOQ)
was established at 0.05 ppm. The Limit of Detection (LOD) was not
reported. 

Recoveries. Untreated raspberry samples collected in a different residue
study were fortified with Metaldehyde at approximately 0.05 and 1 ppm to
validate the method. Recoveries were in the respective ranges 78-108%
and 84-88%. Concurrent recoveries during the analysis of treated and
storage samples were conducted at 0.05, 0.2 and 1 ppm and were in the
composite range 91-112%. 

Storage Stability. Raspberry samples were fortified with Metaldehyde at
approximately 1 ppm and stored frozen for 47 days. Recoveries after this
interval were 88%, 95% and 91%, demonstrating the stability of this
compound. 

5. Magnitude of the Residue-Raspberry

Two raspberry field trials were conducted in Oregon and one in
Washington to develop data in support of the reregistration of
Metaldehyde on berries. Applications were made using a shaker container
with a single aperture. Deadline® M-P’s were applied to the wet and
moist soil in a line on each side of the crop, 1-3 feet from the base of
the plants. The application rate varied slightly between the two test
sites. The Oregon field cooperators used the labeled amount of active
ingredient (4.0%) , which was repeated in the protocol, to determine the
amount of test substance needed for their plot. The Washington field
cooperators used the percent active ingredient listed on the shipping
information (4.3%) to determine the amount of test substance needed for
their plot. The Certificate of Analysis for the test substance states
that the purity was determined to be 4.27 ± 0.14%. Thus, the actual
amount of active ingredient applied per application was 0.854 lb.
ai/acre (Oregon trials) and 0.795 lb. ai/acre (Washington trial). Five
applications at 14-17 day retreatment intervals were made in each trial,
with treated and untreated samples collected on the day of the last
application. The samples were held in frozen storage until delivery to
the analytical laboratory via Federal Express. 

Results. Conduct of these residue trials in Oregon and Washington is
intended to provide data from the primary domestic caneberry-growing
region to support the reregistration of Metaldehyde on berry crops. No
detectable residues above the LOQ of Metaldehyde were found in any of
the untreated samples from the field trials of this study. No detectable
residues above the LOQ of Metaldehyde were found in the treated samples
from the Washington plot. Residues in the range of 0.05-0.06 ppm were
found in the treated samples from the Oregon trials. All of the test
substance had been applied to the ground, suggesting that a small amount
had moved systemically into the fruit. 

6. Analytical Method-Artichoke

Preparation.The samples were received frozen at the North Central Region
Leader Laboratory, National Food Safety and Toxicology Center, Michigan
State University, on December 20, 2001. They were logged in and stored
in a freezer at -26° to -4°C until extraction and analysis.

Method. The samples were analyzed using a modification of the reference
method: Analytical method for the determination of Metaldehyde in
lettuce by GC/MS. ENC-3/99. EN-CAS Analytical Laboratories. The
modification is listed on page 3 of this Notice of Filing under the
Procedure section. The Metaldehyde reference standard (99.4% pure, lot
#A005047103, expiration date 1/12/04) was received from Acros Organics
on 1/12/00. The Limit of Quantitation (LOQ) was established at 0.036
ppm. The Limit of Detection (LOD) was not reported.

Recoveries. Artichoke samples were fortified with Metaldehyde at
approximately 0.05 ppm and 1 ppm in order to validate the method and for
concurrent recoveries. The recoveries were in the respective ranges
88-108% and 103-113%.

Storage Stability. Artichoke samples were fortified with Metaldehyde at
approximately 1 ppm and stored frozen for 119 days. Recoveries were
112%, 107%, and 118%, demonstrating the stability of this compound in
frozen storage.

7. Magnitude of the Residue-Artichoke

Three field trials were conducted in Castroville, California, in order
to collect residue samples of Metaldehyde-treated artichokes. Deadline®
M-P’s were applied by hand towards the ground on each side of the
crop, avoiding contamination of the exposed artichoke buds. The
applications were made at the approximate rate of 20 lbs. per acre (0.8
lbs. active ingredient per acre). Seven applications were made in each
trial onto wet soil. The protocol required application intervals of
18-21 days, but two of the applications in trial CA68 and two of the
applications in trial CA66 had to be delayed in order to coordinate the
applications with the irrigation needed to wet the soil. The longest
application interval was 29 days. Treated and untreated samples of
mature artichoke buds were collected on the day of the seventh
application in each trial. The samples were stored in a freezer until
shipment to the analytical laboratory.

Results. Artichoke field trial samples were extracted and analyzed
February 13 and 14, 2002. No residues of Metaldehyde were found in the
control samples. Some treated samples showed trace Metaldehyde residues
but all were <0.05 ppm, the LLMV. The average recovery of the concurrent
quality assurance samples extracted with these field samples were 98% ±
10%. 

2. Analytical Method-Prickly Pear Cactus

Preparation. The samples were received frozen and intact at the North
Central Region Leader Laboratory, Michigan State University, East
Lansing, MI on 11/17/00 (trial CA 117 and 12/21/00 (trial CA 118). The
samples were logged in and stored frozen at -25 to -14°C until
extraction and analysis.

Methods. The samples were analyzed using a modification of the reference
method: Analytical method for the determination of Metaldehyde in
lettuce by GC/MS. ENC-3/99. EN-CAS Analytical Laboratories. The
modifications are listed under the Procedure section. The metaldehyde
analytical reference standard (lot #A005047103, 99.4% pure, expiration
date 1/12/02) was received on 1/12/00 from Acros Organics of Fair Lawn,
NJ. The limit of quantitation (LOQ) was established at 0.05 ppm for
cactus fruit and cactus pads. 

Procedure. (This procedure is a modification of the method as referenced
under the Method section).

Extraction: To a 15 g chopped subsample in a Mason jar (25 g for the
storage study samples), 150 mL of dichloromethane and 50 g of sodium
sulfate were added. The sample jar was then placed on an Eberbach
horizontal platform shaker and shaken for one hour.

Filtration and Evaporation: The entire sample was filtered through a 50
g pad of anhydrous sodium sulfate (pre-washed with dichloromethane) on
top of a glass wool plug, into a 250 mL Erlenmeyer flask. The Mason jar
and the sodium sulfate pad were rinsed with 25 mL methylene chloride and
the rinsate was combined with the filtrate.

The entire filtrate was quantitatively transferred to a graduate
cylinder and measured. 

One half the amount was evaporated to approximately 1-5mL using a
turboVap with a water bath temperature below 30°C.

The solution was adjusted to an appropriate volume with dichloromethane
for GC/MS analysis.

All final sample extracts were stored in a laboratory grade freezer at
temperatures ranging from -31°C to -17°C if not analyzed immediately
after extraction.

Recoveries. The method was validated by fortifying cactus fruit and
cactus pads with metaldehyde at the rates of 0.05020 ppm and 1.004 ppm.
The recoveries in fruit at these rates were in the respective ranges
79-83% and 68-82%. The recoveries in pads at these rates were in the
ranges 91-106% and 93-119%, respectively. 

Concurrent recoveries in cactus fruit were 102% and 117% at 0.05020 ppm
and 89% at 1.004 ppm. Concurrent recoveries in cactus pads were 116% and
99% at 0.05020 ppm and 95% at 1.004 ppm.

Storage Stability. Cactus fruit that had been fortified with metaldehyde
at approximately 1 ppm and stored frozen for 78 days yielded recoveries
of 81%, 91% and 98%. Cactus pads that had been fortified with
metaldehyde at approximately 1 ppm and stored frozen for 80 days yielded
recoveries of 86%, 95%, and 101%. These results demonstrate the
stability of metaldehyde in frozen storage during the length of time
that the treated samples were stored until extraction and analysis. 

3. Magnitude of the Residue- Prickly Pear Cactus

Two field trails were conducted on a commercial prickly pear cactus farm
in Gonzalez, Monterey County, California. (The two trials had different
dates of initiation and completion). Six applications of Deadline®
M-Ps, 0.8 lb active ingredient per acre, were made to each treated plot
at intervals of 29 and 33 days.  The mini-pellets were applied to the
(wet) ground in a band 1-3 feet from the base of the cactus plants on
each side. The applications were made using

a shaker container with a single aperture. Treated and untreated samples
of fruit and pads were collected following the sixth application, on the
same day as that application. The samples were stored frozen until
shipment to the analytical laboratory via ACDS freezer truck. 

Results. No detectable residues of metaldehyde above the LOQ were found
in any of the treated or untreated cactus fruit. No residues of
metaldehyde above the LOQ were found in any of the untreated cactus
pads. Three of the four treated pads had no detectable residue above the
LOQ, whereas the fourth sample had a residue of 0.05 ppm.

B.  Toxicological Profile  

1.  Acute toxicity.  Acute mammalian studies include oral, dermal and
inhalation toxicity, eye and skin irritation, and skin sensitization. 
The acute oral LD ADVANCE \d3 50 ADVANCE \u3 s in rats and mice were
determined to be 283 and 425 mg/kg, respectively.  The acute dermal LD
ADVANCE \d3 50 ADVANCE \u3  and acute inhalation LC ADVANCE \d3 50
ADVANCE \u3  in rats were determined to be > 5 g/kg and > 15 mg/l,
respectively (MRIDs 131434 and 131429).  When instilled into the eye of
the rabbit, slight transient iridial and conjunctival irritation were
observed during the first 48 hours after instillation (MRID 42068801). 
No irritation was observed when Metaldehyde was applied to the skin of
the rabbit (MRID 131971).  In a dermal sensitization study conducted in
guinea pigs, Metaldehyde was shown to be nonsensitizing (MRID 153405).  

2.  Genotoxicity. A battery of tests have been conducted including
assays for gene mutation in bacterial cells (MRIDs 131433 and 41553205),
chromosomal aberrations in mammalian cells (MRID 163832), an in vitro
gene mutation assay in mouse lymphoma L5178Y cells (MRIDs 41553206 and
42044007) , an in vivo micronucleus test in the mouse (MRID 42044006).
Metaldehyde was not active in any of these assays. 

3.  Reproductive and Developmental Toxicity.  A developmental toxicity
study in rats was conducted at Metaldehdye dose levels of 0, 25, 75 and
150 mg/kg/day (MRID 41656001). The doses were administered via oral
gavage on gestational days 6-15. At the 150 mg/kg/day dose level, marked
treatment-related effects including death were observed. There were no
indications of maternal toxicity at 25 and 75 mg/kg/day. There was no
impact on gestational parameters or external, visceral or skeletal
variations or malformations observed at any dose level tested. The
maternal no-observed effect level (NOEL) was 75 mg/kg/day and the
developmental NOEL was greater than the highest dose level tested of 150
mg/kg/day. 

A developmental toxicity study in New Zealand White rabbits was
conducted at Metaldehyde dose levels of 0, 10, 40 and 80 mg/kg/day
(MRID 41590501).  These dose levels were selected on the basis of a
dose range finding study in which clear evidence of maternal toxicity
was observed at dose levels ( 100 mg/kg/day.  The doses were
administered via oral gavage on gestational days 6 – 18.  There were
no effects on maternal body weight, weight gain, clinical signs or
necropsy findings.  There was no impact on gestational parameters, or
external, visceral or skeletal variations or malformations at any of the
dose levels tested.  The maternal and developmental toxicity NOEL was
greater than the highest dose tested (80 mg/kg/day). 

A two-generation reproduction study was conducted in rats fed diets
containing 0, 50, 1000 and 2000 ppm of Metaldehyde (MRID 42823101). 
Treatment-related effects were limited to the animals in the 2000 ppm
treatment group during the F0 phase of the study.  These effects
included transient decreases in body weight gain and incidences of hind
limb paralysis due to vertebral fractures and luxations in F0 females. 
F1 pup body weights also were reduced during the last two weeks of
lactation.  During the F1 phase of the study, depressed body weight
and/or food consumption in the 1000 and 2000 ppm treatment groups was
observed in the maternal animals.  One F1 female in the high dose group
also exhibited prostration and other clinical signs during delivery. 
Absolute and relative liver weights were increased in the F1 males and
females at 2000 ppm.  F2 pup body weights in the 2000 ppm treatment
group also were reduced during the lactation period.  No effects on the
reproductive parameters, litter viability or pup survival were observed
during either generation.  The NOEL for adult toxicity was 50 ppm; the
NOEL for offspring was 1000 ppm and the NOEL for reproductive effects
was greater than 2000 ppm.  

4.  Subchronic toxicity.   A 21-day dermal toxicity study was conducted
in New Zealand White rabbits (MRID 42063401).  In this study,
Metaldehyde was applied to the shaven backs of the rabbits and wrapped
in gauze moistened with water for six to eight hours per day, five days
per week for three weeks.  Three dosage levels, including the maximum
dose that could be applied in this test system, i.e. 1000 mg/kg/bw, were
evaluated.  With the exception of minor skin irritation at the site of
application, no treatment-related effects were observed.  Therefore, the
NOEL for systemic toxicity was 1000 mg/kg/day.

A 90-day repeated dose dietary neurotoxicity study in Sprague-Dawley
CD® rats was conducted at Metaldehyde dietary concentrations of 0, 100,
500 and 2500 ppm (equivalent to 0, 8, 39 and 185 mg/kg/day,
respectively) (MRID 46223401).  With the exception of one female in the
2500 ppm treatment group that showed loss of hind limb function,
increased respiration, wet fur, and red/brown staining around the
anogenital region, no clinical signs of toxicity were observed in any of
the dose groups.  Females in the 2500 ppm treatment group had decreased
body weight gain during the first week of the study.  No
treatment-related effects were observed in the behavioral, functional or
sensory assessments of neurotoxicity.  The NOEL for neurotoxicity was
considered to be 500 ppm (39 mg/kg/day).

5.  Chronic toxicity.  A six-month chronic toxicity study was conducted
in Beagle dogs (MRID 131432). Metaldehyde dose levels of 0, 20, 60 and
90 mg/kg/day were administered via the diet.  No clear evidence of
systemic toxicity was observed in any of the treatment groups. 

A 52-week chronic toxicity study in dogs was conducted by administering
Metaldehyde via the diet at concentrations of 0, 10, 30 and 90 mg/kg/day
(MRID 46378401).  Clinical signs observed in the high-dose group
included ataxia, emesis, salivation, tremor and twitching.  Reduced body
weight gain, changes in hematological and biochemical parameters and in
increased absolute and relative liver weight also were noted for the
animals in this group.  Histopathology revealed morphological changes in
the testes and prostate of the animals treated with 90 mg/kg/day in the
form of an atrophy and/or degeneration of the germinative epithelium
with giant cells.  One mid- and high-dose female and one mid-dose male
died prior to the terminal sacrifice.  The study director attributed all
three deaths to treatment with Metaldehyde and defined the no-observed
adverse effect level (NOAEL) as 10 mg/kg/day on this basis.  Since
there were no other treatment-related effects observed in the 30
mg/kg/day dose group, it is somewhat questionable as to whether or not
the two deaths in the mid dose group should be attributed to
Metaldehyde treatment.

An oncogenicity study was conducted for a period of 78 weeks in Charles
River CD-1 ADVANCE \u3  ADVANCE \d3  mice (MRID 42737201).  Metaldehyde
dietary concentrations of 0, 25, 100 and 300 ppm were evaluated
(equivalent to 4, 16 and 49 mg/kg/day for the males and 0, 5, 20 and
60 mg/kg/day for the females, respectively). The only treatment-related
effect was hepatocellular hypertrophy in the 300 ppm dose group.  Pair
wise comparisons and/or life table analyses did not indicate any
treatment-related effects on survival, tumor incidence or time to tumor.
 

Because the criteria for a maximum tolerated dose was not satisfied in
the initial oncogenicity study, a second 78-week chronic oncogenicity
study was conducted in Charles River CD-1 ADVANCE \u3  ADVANCE \d3  mice
(MRID 44625101).  In this study, Metaldehyde dietary concentrations of 0
and 1000 ppm were evaluated (equivalent to 0 and 135 mg/kg/day for the
males and 0 and 163 mg/kg/day for the females).  The exposure of mice
to 1000 ppm of Metaldehyde in the diet did not result in clinical signs
of toxicity or changes in survival, body weight, hematology or
toxicologically significant changes in food consumption. 
Treatment-related increases in liver weight and histopathological
lesions in the liver of male mice, and to a lesser extent, of female
mice were observed.  Significant histopathologic lesions observed in
Metaldehyde treated mice included hepatocellular hypertrophy in male and
female mice and single cell necrosis, focal and multifocal necrosis,
pigment accumulation, sinusoidal histiocytosis and hepatocellular
adenoma in male mice. A small increase in the incidence of
hepatocellular eosinophilic cell foci or hepatocellular adenoma in
female mice treated with 1000 ppm Metaldehyde also was observed.  The
nature of these changes was consistent with an adaptive hypertrophic
response of the liver to an increase in metabolic demand with subsequent
development of proliferative changes and hepatocellular toxicity.  There
were no other treatment-related findings.

A cell proliferation assay (MRID 44810901) was conducted in order to
further investigate the mechanism by which the increase in benign liver
tumors occurred in the mouse oncogenicity study.  Archival material from
a mouse 90-day dose range-finding study was used for this evaluation.  A
clear dose response for cell proliferation in the liver was observed in
this assay.  These findings support the conclusion that the increased
incidence of benign liver tumors observed in the mouse oncogenicity
study resulted from cell proliferative effects secondary to cytotoxicity
rather than a direct oncogenic effect of Metaldehyde. 

A chronic toxicity/oncogenicity study was conducted for a period of
104 weeks in Sprague-Dawley CD® rats (MRID 42203601).  Metaldehyde
dietary concentrations of 0, 50, 1000 or 5000 ppm (equivalent to 0, 2,
44, and 224 mg/kg/day for the males and 0, 3, 60 and 314 mg/kg/day for
the females) were evaluated.  No biologically significant differences in
mortality, clinical signs of toxicity, palpable masses or food
consumption were observed in any of the treatment groups.  Treatment of
both male and female rats with 5000 ppm Metaldehyde resulted in
decreased body weight and weight gain throughout the test period,
increases in both absolute and relative liver weights, and an a
numerical increase in the incidence of females at necropsy with liver
masses and/or nodules at necropsy.  Increased serum globulin and
increased serum cholesterol for females only, hepatocellular hypertrophy
for males and females, and a questionable increase in the incidence of
females with hepatocellular adenomas were observed in the high-dose
group.  These benign neoplasms occurred late in the course of the study
and were within the range of historical control incidences for the same
tumor.  Therefore, this small numerical increase in hepatocellular
adenomas was attributed to an uncommonly low number of such tumors in
the concurrent control animals.  Treatment-related effects in animals
fed diets containing 1000 ppm Metaldehyde were lower body weight and
body weight gain in the males and females for the first year of the
study, increased serum cholesterol for females only, and hepatocellular
hypertrophy for males and females.  The NOEL for systemic toxicity after
104 weeks of dietary administration to rats was 50 ppm (2.0 mg/kg/day
for males and 3.0 mg/kg/day for females).

6.  Animal metabolism.  A study was conducted in Charles River CD
ADVANCE \u3  ADVANCE \d3  rats to determine the absorption,
distribution, metabolism and excretion patterns of 14C-Metaldehyde
following oral dose administration (MRID 42300901).  The results of the
study showed that orally administered Metaldehyde is readily absorbed
from the gastrointestinal tract and quantitatively metabolized to
acetaldehyde, which in turn is converted to acetyl-C0A as it enters the
Krebs cycle.  This allowed the 14C label to be eliminated as 14C-C02 and
to enter the two carbon pool resulting in persistent 14C residues in
tissue.  The majority of the Metaldehyde was eliminated as 14C-CO
ADVANCE \d3 2 ADVANCE \u3 .  

7.  Metabolite toxicology.  The only residue found in plants was parent
Metaldehyde.  In animal systems, Metaldehyde is metabolized to
acetaldehyde (a normal body constituent) and CO2.  Therefore, only
parent Metaldehyde is included in the proposed tolerance expressions and
in the risk exposure assessment.

8.  Endocrine effects.  No special studies investigating the potential
estrogenic or other endocrine effects of Metaldehyde have been
conducted.  However, the standard battery of required toxicology studies
has been completed.  These include an evaluation of the potential
effects on reproduction and development, and an evaluation of the
pathology of the endocrine organs following repeated or long-term
exposure to doses that far exceed likely human exposures.  Based on  
these studies there is no evidence to suggest that Metaldehyde has an
adverse effect on the endocrine system.

C. Aggregate Exposure

1. Dietary exposure.  

Acute and chronic dietary risk assessments were conducted (MRID
46524301) for Metaldehyde using the Dietary Exposure Evaluation Model
(DEEM) and the USDA Continuing Survey of Food Intake by Individuals
(CSFII, for 1994 to 1996, as contained in DEEM).  For these assessments,
three Tiers were examined (only Tiers III and I are discussed herein):

	Tier I – Highest average field trial (HAFT) residue values were
used    and 100 percent crop treated was assumed (worst-case scenario);

	Tier II - Average field trial values and 100 percent crop treated
were used; 

Tier III - Both average field trial values and the estimated percent
crop treated were used (the most realistic evaluation of dietary
exposure). 

Proposed tolerances were used to estimate dietary exposure from the
consumption of:

	Artichokes (individual crop);

	Berry crop group;

	Brassica (cole) crop group – broccoli, cabbage, mustard greens;

Citrus crop group – grapefruit, lemons, oranges and processed
commodities;

	Fruiting vegetables (tomato and processed commodities);

	Leafy vegetables (lettuce);

	Prickly pear cactus;

	Strawberry;

	Watercress  

The results of both the chronic and acute dietary and drinking water
exposure analyses clearly demonstrate a reasonable certainty that no
harm will result from the proposed uses of Metaldehyde.

A.  Acute  Dietary Exposure.  

Based on the DEEM Tier III acute dietary risk assessment, exposure at
the 95th percentile for the overall U.S. population was estimated to be
0.000139 mg/kg/day, which yields a Margin of Exposure (MOE) >530,000
(0.02% of the acute RfD of 0.75 mg/kg bw/day).  The highest exposed
population subgroup, children 1-2 years, had an acute exposure at the
95th percentile that was estimated to be 0.000347 mg/kg bw/day yielding
an MOE > 210,000 (0.05% of the RfD).  The acute exposure analysis shows
that for all populations, the MOE falls well above the acceptable level
of 100.

Based on the DEEM Tier I (worst-case) analysis acute dietary risk
assessment, exposure at the 95th percentile for the overall U.S.
population was estimated to be 0.007983 mg/kg/day, which yields a Margin
of Exposure (MOE) >9000 (1.1% of the RfD). The highest exposed
population subgroup, children 1-2 years, had an acute exposure at the
95th percentile that was estimated to be 0.01812 mg/kg bw/day yielding
an MOE > 4000 (2.4% of the RfD).  This acute exposure analysis also
shows that for all populations, the MOE falls well above the acceptable
level of 100.

B. Chronic Dietary Exposure.  

i. Food:  Based on the DEEM Tier III chronic dietary risk assessment,
the exposure for the overall U.S. population was estimated to be
0.000046 mg/kg bw/day, which is 0.2% of the estimated chronic RfD of
0.025 mg/kg bw/day.  The highest exposed subgroup, children 1-2 years,
had a chronic exposure of 0.000114 mg/kg bw/day (0.5% of the RfD). 
Based on the DEEM Tier I (worst-case) chronic dietary risk assessment,
the exposure for the overall U.S. population was estimated to be
0.002093 mg/kg bw/day, which is 8.4% of the estimated RfD of 0.025 mg/kg
bw/day.  The highest exposed subgroup, children 1-2 years, had a chronic
exposure of 0.004730 mg/kg bw/day (18.9% of the RfD).

ii. Drinking water: Tier 2 surface water concentration estimates (peak
or acute = 40 ppb and annual average or chronic = 22 ppb), which are
assumed to conservatively represent drinking water residue estimates,
were generated using the FIRST and

PRZM/EXAMS (FQPA Index Reservoir Screening Tool; Version 1.0; PRZM

(3.12 beta/EXAMS (2.98.04) results for instantaneous release and slow
release a.i.; respectively) model (Ma and Cohen, 2005) and used to
estimate potential drinking water exposures.  A conservative estimate of
potential shallow ground water contamination, i.e., 12.4 ppb was also
estimated using SCI-GROW (Cohen and Barnes 2005).  Based on the
worst-case chronic exposure value of 22 ppb the chronic exposure for the
overall U.S. population and children 1-2 years is estimated to be
0.000629 and 0.000627 mg/kg bw/day, respectively (MOEs > 3900). 

2.   Non-dietary exposure.  

A deterministic non-dietary (non-occupational) risk assessment using the
Residential Exposure Assessment (Rex) model was performed for
Metaldehyde applied to the ground in and around ornamental plants, small
fruit and berry plants, fruit trees, vegetable garden areas (MRID
46524302).  The maximum application rate of 3.5 lbs of active ingredient
(a.i.) per acre was used.  For purposes of a conservative or
“high-end” residential exposure scenario and health risk evaluation,
it was assumed that an adult consumer applies the granular formulation
by hand without gloves.  In accordance with EPA guidance,
post-application exposures associated with formulations applied to
ground areas in and around gardens, ornamentals, and trees were
considered negligible and were not addressed.  

A separate assessment for use of Metaldehyde in lawn care applications
was also performed (MRID 46524304).  For purposes of this residential
exposure and risk evaluation, it was conservatively assumed that an
adult consumer applies the formulation by either hand dispersion (spot
treatment) or a push-spreader (broadcast treatment) at the highest
application rate of 1.0 lb a.i./acre for this use pattern.  It was
assumed that gloves are not used.  Potential consumer exposures and
associated health risks were evaluated for adult applicators under these
circumstances. Potential post-application or reentry exposures
associated with broadcast applications were also evaluated.

The results for the non-dietary (non-occupational) risk assessment
indicate that acceptable MOEs exist for the vegetable garden (and by
inference small fruits and berries), ornamental, and tree care hand
dispersion scenarios.  Using worst-case conditions (e.g., no gloves
during application, maximum application rates, 1,000 square feet being
treated for each setting, i.e., gardens, ornamentals and trees), the
overall aggregate MOE for the adult applicator (dermal and inhalation
routes) was approximately 400 assuming the same person applied granules
to all three settings (vegetable gardens, ornamentals, and trees) on the
same day.  This aggregate MOE would be increased to approximately 3,760
if gloves were used per label recommendations.  More realistically, an
adult might apply granules to only one of the three scenarios.  The
scenario-specific overall or total MOEs (dermal and inhalation combined
as total MOE = [1 / (1 / dermal MOE) + (1 / inhalation MOE)] are
identical, i.e., approximately 1220, for vegetable garden, ornamental
plant, and tree care.  If the applicator used gloves, per label
instructions, the scenario-specific total MOE would be approximately
11,280 for vegetable garden, ornamental plant, and tree care.  The
increase in the MOE is attributed to the glove-based dermal unit
exposure value of 71 mg/lb a.i., versus the estimated “no glove”
dermal unit exposure value of 710 mg/lb a.i.

The results of the screening-level, non-dietary (residential) consumer
applicator (dermal and inhalation) and post-application (adult dermal,
and child dermal and incidental ingestion) risk analysis for Metaldehyde
use for lawn care, demonstrate that acceptable Margins of Exposure
(MOEs) exist for various lawn care methods evaluated, i.e., spot
treatment of lawns via hand dispersion of granules or low pressure
hand-wand spraying, or granular broadcast treatment of lawns via
push-spreaders.  Using worst-case conditions (e.g., no gloves during
application, maximum application rates, high contact reentry activities
on the day of broadcast treatment), the overall total intake ranged from
approximately 0.232 mg/kg/day for the adult applicator (dermal and
inhalation routes; MOE= 3950) for granular lawn broadcast treatment
(push spreader) to 0.0328 mg/kg/day (MOE = 30,370) for spot treatment
using a low pressure hand-wand sprayer.  The applicator MOEs would
increase significantly if gloves were used.  The overall or total intake
(via dermal and incidental oral exposure) for children (1 – 6 yrs) in
the case of the granular lawn broadcast scenario was approximately 0.403
mg/kg/day (MOE= 1,700).  This MOE is conservative, given assumptions
regarding reentry on the day of application and two hours of high
contact activity on the lawn, including frequent hand to mouth transfer.
 

Based on this assessment, it can be concluded that the potential
residential/consumer application exposures associated with the use of
Metaldehyde-based products for slug and snail control are associated
with a “reasonable certainty of no harm.”  

D. Cumulative Effects

There is no evidence to indicate or suggest that Metaldehyde has any
toxic effects on mammals that would be cumulative with those of any
other chemicals.

E. Safety Determination

Acute and chronic dietary risk assessments were conducted for
Metaldehyde using the Dietary Exposure Evaluation Model (DEEM).  Dietary
exposure to Metaldehyde was based on the following crop group uses: 
artichokes, Berry crop group, Brassica (cole) crop group, Citrus crop
group and processed commodities, tomato and processed commodities,
lettuce, prickly pear cactus, strawberry, and watercress.

 LISTNUM 2 \l 1 	U.S. Population:  Using the Tier III data (most
representative of actual exposure), for the overall U.S. population, the
predicted acute exposure is 0.000139 mg/kg bw/day.  Based on the acute
NOAEL and reference dose (75 and 0.75 mg/kg bw/day, respectively), this
exposure estimate results in intake of 0.02% or less of the estimated
aRfD at the 95th percentile (MOE > 530,000).  Using the Tier III data
for the U.S. population, the predicted chronic exposure for the overall
U.S. population is 0.000046 mg/kg bw/day, or 0.2% of the estimated cRfD
(based on the chronic NOAEL of 2.5 mg/kg bw/day;  cRfD of 0.0025 mg/kg
bw day).

Because the predicted exposures, expressed as percentages of the aRfD
and cRfD are well below 100%, there is reasonable certainty that no
acute or chronic effects in the U.S. population would result from
dietary exposure to Metaldehyde.  

 

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萏Ԑ萑*葞Ԑ葠*摧僘«܀000347 mg/kg bw/day, or 0.05% of the aRfD
(MOE > 210,000).  The estimated chronic exposure was 0.000114 mg/kg
bw/day equivalent to 0.5% of the cRfD.

Because the predicted exposures, expressed as percentages of the aRfD
and cRfD are well below 100%, there is reasonable certainty that no
acute or chronic effects would result in the population subgroup with
the highest level of exposure (children 1-2 years) from dietary exposure
to Metaldehyde.  

F. International Tolerances

No incompatibilities with international tolerances are expected.

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