United States Office of Peflicidas and Toxic Subttaneei
Environmental Protection Office of Pesticide Programs (TS-766C)
Agency Washington. DC 20460
&EPA Pesticide
Fact Sheet
Name of Chemical: AVERMECTIN
Reason for Issuance: New Chemical Registration
Date Issued: April is, 1986
Fact Sheet Number:
89
1. DESCRIPTION OF CHEMICAL
Generic Name: Avermectin Bj [A mixture of avermectins containing >^ 80%
avermectin B^a (5-O-diroethyl-avermectin Aia) and £ 20%
avermectin B^b (5-O-demethyl-25-de(l-methylpropyl)-25-
(1-methylethyl)avermectin Aja)]
Common Name: None assigned.
Trade Name: Affirm1"
EPA Shaughnessy Code: 0122804
Chemical Abstracts Service (CAS) Numbers: 65195-55-3 and 65195-56-4
Year of Initial Registration: 1986
Pesticide Type: Insecticide
Chemical Family: Avermectins (macrocylic lactones isolated from
soil organism Streptomyces avermitilis).
U.S. Producers: Merck Sharp S. Dohme Research Laboratories
2. USE PATTERNS AND FORMULATIONS
Application Sites: Turf, lawns and other non-crop wide outdoor
areas.
Type of Formulations: 0.011% insecticide bait.
Method of Application: Bait broadcast (ground or air application)
and individual mound to mound treatment.
Application Rates: 50 mg active ingredient (A.I.) per acre
(1 pound of product per acre).
Usual Carriers: Pregelled defatted corn grit carrier.
Limitations: Do not use in pastures, rangeland, or croplands.
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3. SCIENCE FIN )INCS
&nii ary Science Statement :
Technical avermectin exhibits high rnanr a1ian acute toxicity. It
is not considered to be inutaqenic nor teratoqenic and does not sensitize
skin. It is not readily absorbed by mamals and the majority of the
residue is excreted in the feces. The results of the acute toxicity on
the bait formulation indicates that it is of low toxicity. Chronic
feeding and oncogenicity studies and a three—qeneration reproduction
study are currently in progress and will be required in support of
food/feed crop uses.
Sufficient data are available to characterize avermectin fran an
environmental fate and ecological stand point. Avermectin is extremely
toxic to fish and aquatic invertebrates and highly toxic to birds. However,
because of its low use rate and rapid rate of photolysis no adverse acute
or chronic effects to aauatic, estuarine or endanoered species are expected.
The degradation products are less toxic than the parent and tend to becane
less toxic as they continue to degrade. Avermectin undergoes rapid photolysis,
is readily degraded by soil microorganisms and, due to its binding properties
and low water solubility, is expected to exhibit little or no potential for
leaching.
A tolerance assessment is not needed because the registered use
pattern is for non—crop/non—food use. There are no data gaps.
A. Chemical Characteristics :
Physical State: Crystalline po .x1er.
Color: Yellowish—white.
Odor: C orless.
Melting Point: 155 — 157°C.
Vapor Pressure: Being tested, expected to be extremely low.
L nsity: 1.16 ÷ 0.05 at 21°C.
Solubility: Insoluble in water (< S uo/ml), readily soluble in
organic solvents.
pH: NA. The avermectin molecule has neither acidic nor basic
functional groups.
c tanol/Water Partition Coefficient: 9.9 x if ) 3
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B. ‘ . [ bxicoloqical Characteristics:
Technical Avermectin
Acute Oral: 1.52 rrq/kq. Toxicity Category I.
Acute E rrnal: LD >380 mg/kg. 1 xicity Category II.
21-day E rmal: Noel is 125 mg/kg/day
Derrnal Sensitization: Negative for skin sensitization.
Acute Inhalation: 1.62 mg/i. Toxicity Category II.
TeratcKlenicity: Three teratology studies (rat, rahhit, and
mouse) have been evaluated to determine the
teratogenic potential of avermectin. Terato—
cienic effects were negative for the rat up
to 1.F mg/kg/day and for the rabbit up to
2.0 mg/kg/day. Avernectin was positive in
the mouse at 0.4 mg/kg/day and the NOEL for
these effects was 0.2 mg/kg/day. However,
the margin of safety between the NOEL and
exposure to applicators and persons upon re-
entry is estimated to be greater than 10,000.
Mutagenicity: Adequate studies are available to demonstrate
that avermectin is not a rnutagen. Avermectin
was not rnutaaenic in the Ames assay and in vivo
bone marrow cytogenetics. In rat hepatocytes,
Avermectin caused an induction of sinale strand
DNA breaks in vitro . No effect was observed when
this same assay was carried out in hepatoocytes
fran rats dosed in vivo at the Lr) p (10. nr /’ i).
In the mammalian cell mutaqenic assay, •\vermectin
was not mutapenic for V—79 cells.
Metabo1i (rats): The metabolic T 1/2 in rats is 1.2 days.
Avermectin does not bioeccumulate in rats.
Affirm Fire Ant Formulation
Oral LD 50 in rats: LI ) 50 > 5.0 gin/kg. Toxicity Category III.
t rma1 L i ) 50 in rats: LD 50 > 2.0 gm/kg. Toxicity Category III.
Acute inhalation LCSO: Not required due to large particle size
and low vapor pressure of technical.
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Primary eye irritation: Thxicity Category III.
I
Primary skin irritation: No irritation. Tbxicity Category lit.
C. Physiological and Biological Characteristics :
Folier absorption: not absorbed.
Translocation: not translocated.
Mechanism of Pesticide tion: Avermectin is b aminobutyric
acid (GARA) agonist, and thus
acts in ar-thropods by inhibiting
nervous siqnal transmission at
the neurc uscular juncture
causina paralysis. No effect
on any cholinergic nervous
systems have been demonstrated.
D. Environmental Characteristics :
Avermectin is not expected to hydrolyze in the environment.
It photodegrades rapidly in water and soil with half—lives less
than 1 day. Soil metabolism studies conducted in darkness
indicate degradation does occur with a half—life of 2 eks to
2 months under aerobic conditions. Anaerobic degradation is slower.
It is not expected to accumulate in fish. Avermectin’s solubility
in water is determined to be 7.8 ppb. The field dissipation study
indicates that avermectin, when applied in the bait formulation
directly to the soil, dissipates with a half life of about a week
but may persist longer if the bait is shaded. Avermectin and its
deqradates do not leach into the soil. There are no concerns at
this tine in regard to ground water contamination. LXie to low
application rates, it is unlikely that there would be any significant
exposure to humans and nontarciet organisms.
E. Ecological Characteristics:
Avian Oral: Bobwhite quail — LD5f) > 2000 mg/kg.
Bobwhite quail — LC = 3102 pr .
Avian Dietary: Mallard duck — LC 50 = 383 p xn.
Freshwater Fish: Bluegill — LC 50 = 9.6 ppb.
Rainbow trout — LC 50 = 3.2 pph.
Acute Freshwater Invertebrate: Daphnia — LC 50 = 0.22 ppb.
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Acute Estuarine Invertebrate: Shrimp, mysid — LC 5 r) = 0.2 ppb.
Estuarine Fish: Fathead minnow — LC p = 15 pph.
OVster D’nhryo Larvae: LC 50 = 430 ppb.
4. SUMMARY OF REQJLAIORY POSITION AND RATIONALE
The k ency has determined that it should allow the reaistration
of avermectin for non—crop, wide area general outdoor use for control of the
imported fire ant. Mequate studies are available to assess the acute
toxicological effects of averrnectin to humans. Since the proposed use is a
non—focd,’fc d se a tolerance asses nent is not necessary. No reentry
interval is necessary. Available data are sufficient to characterize the
environmental fate of averrnectin. Although technical avermectin is
highly toxic to fish, birds, and invertebrates, the 50 ma/acre rate plus
rapid degradation should minimize this potential hazard. The effectiveness
of the 5ait. formulation has been extensively tested by USDA and also by
the registrant under an EPA—approved experimental use permit from 1982—1985.
None of the criteria for unreasonable adverse effects listed in section
162.11(a) of Title 40 of the U.S. Ccxie of Federal Regulations have been
met or exceeded for this use.
5. SUMMARY OF RAJOR DATA GAPS
There are no data gaps for the present use pattern.
6. CONTACT PERSON AT EPA
Georae T. U Rocca
Product 1anager 15
ir ecticide—P oienticide Sranch
Reqistr tion r)ivision (TS—767C)
401 M street S W.
!ashington, 1X 20460
(703) 557—2400
DISCLAIMER: The information presented in this Chemial Information
Eact Sheet is for informational purposes only and may not he used to
fulfill data requirements for pesticide registration and reregistration.
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