Unftod State* Office of Pestickta and Toxic Subctancaf
Environmental Protection Office of Pesticide Program* (TS-766C)
Agency Waihington, DC 20460
<>EPA Pesticide
Fact Sheet
Name of Chemical: „ . ,
_ Naled
Reason for Issuance:
Date Issued: June 30' 1983
Fact Sheet Number:
1. Description of Chemical
Generic name: 1,2-dibromo-2,2-dichioroethyl dimethyl phosphate
Common name: Naled
Trade name: Dibrom*
EPA Shaughnessy code: 034401
Chemical abstracts service (CAS) number: 300-76-5
Year of initial registration: 1959
Pesticide type: insecticide - acaricide
Chemical family: organophosphate
U.S. and foreign producers: Chevron Chemical Co.
2. Use patterns and formulations
Application sites: field, vegetable, and orchard crops;
livestock and poultry, anc their surroundings; green-
houses; forest ana wastelanc; agricultural, domestic,
medical, and commercial establishments; and urban and
rural outdoor areas (mosquito control).
Types of formulations: dusts, impregnated materials,
emulsifiable concentrates, soluble concentrates, liquid
and ready-to-use liquids.
Types and methods of application: aerial and ground as a
spray or dust; fogging; ultra low volume (ULV)
Application rates: varies from .01 to 10 Ibs/acre
Usual carriers: Confidential Business Information
3. Science Findings
Summary science statement:
Available acute oral and dermal LD5Q data place naled in
toxicity category II and toxicity category I based on primary
eye irritation data.
Naled is characterized as very highly toxic to bees and
aquatic invertebrates. It is moderately to highly toxic to
fish and slightly toxic to upland game birds and waterfowl.*
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Naled has numerous data gaps in areas of product cheu istry,
residue chemistry, toxicity, environmental fate and ecological
effects. The Agency’cannot conduct a full risk assessment
until the data required in the Naled Standard are submitted
and evaluated.
Chemical characteristics :
Manufacturing—use naled is a light, straw—colored, oily
liquid with a slightly pungent odor. The pure compound
is a white, low melting point solid. The boiling point
for pure naled is 120°C at 0.5 mm Hg and the vapor pressure
is 2 x 10 mm Hg at 20°C. The empirical formula is
C 4 H 7 O 4 PBr 2 C1 2 and the molecular weight is 381. Naled
has limited solubility in aliphatic solvents; is highly
soluble in oxygenated solvents such ketones and alcohols;
and a low solubility in water.
Toxicological characteristics :
Current available toxicology studies on naled are as
follows:
— Acute oral LD 50 : rat, 222—389 mg/kg; mouse, 160 mg/kg
(Tox category II)
— Acute dermal LD 50 : rabbit, 390—1100 mg/kg;
rat, 800 mg/K; (Tox category II)
- Primary eye irritation: corneal opacities 7 days+
(Tox category 1;
— Primary dermal irritation: rabbit, PIS 5.8 — 5.92;
humar. volunteers, severe irritatior
- Subcnronic feecing: choiinesterase NOEL in cog,
C.25 mg/kg/day
Additional cata are needed to fully assess the toxicity
of naled.
Major routes of exposure: application by fog and mist
sprayers, and aircraft increases the potential for
exposure of humans and non—target organisms to naled.
Human exposure to naled during mixing, handling,
application, and reentry operations would be mini-
mized by the use of approved respirators and other
protective clothing. However, data are not available
to fully assess sucn exposures. PR Notice 83—2 sets
forth current Agency policy on required label changes
for reentry and farrnv orker safety. A reentry level of
24 hours for the use of naled on crops is required.
Physiological and Biochemical Behavioral Characteristics :
Mechanism of pesticidal action: stomach and/or contact
poison
Metabolism and persistence in plants and animals: no naled
or DDVP was detected in tissues or milk of two goats
dosed with naled at 107 ppm in three equal daily portions
and and sacrificed on day 4. The limits of detection
were 0.05 ppm for tissues and 0.005 ppm for milk. The
dose is estimated to be about twenty times that which
would normally occur in the goats diet.
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Residues were non—detectable (<0.01 ppm) in milk trom
Holstein cows subject to body and premise sprays for 14
days with the 7.2 lb/gal EC formulation.
Environmental Characteristics :
Naled degrades fairly rapidly with haif—lifes of 8
hours in soils and 25 hours in aqueous solutions.
Dichlorvos (DDVP), a metabolite of naled is also rapidly
degraded in soil with half—lifes of 2.3 — 8.0 hours.
Naled exhibits low to intermediate mobility in soils,
whereas dichiorvos is intermediately mobile to mobile.
Limited data indicate that the rapid dissipation and
relatively low mobility of naled and intermedite mobility
of dichlorvos in soil will mitigate contamination of
ground water.
Nalec dic not accumulate in wnole body tissues of kill-
fish exposed to naled in static bioassy tests. Naled
was not detected (<0.02 ppm) in any fish tissue samples
taken over the v—day test period. The degradate dichlor—
vos was found at a maximurr concentration of 0.04 ppm,
approximately twice the concentration in corresponding
water samples, 1 hour after treatment, but was not
found (<0.01 ppm) in tissue samples taken after 24
hours. Naled haif—lite in water samples was <24 hours.
Dichlorvos was found in all water samples, at a maximum
concentration of 0.02 ppm after 24 hours, but <0.01
ppm was found in samples taken at the end of the test
period.
In summary naled and its degradate dichlorvos dissipate
rapidly in aerobic soils. Naled exhibits low to inter-
mediate mobility in soils, whereas, dichlorvos is inter-
mediately mobile to mobile. Mobility appears to be
related to soil organic matter content. Naled degrades
rapidly in aqueous solution, with rates increasing at
higher temperatures and pHs. Naled also rapidly degrades
in sewage water to dichiorvos and dichloroacetaldehyde.
Neither naled nor dichlorvos accumulate in fish tissues.
In conclusion, naled does not appear to represent an
environmental hazard based on the aforementioned data
which indicate very rapid degradation and extremely low
bioaccumulation potential.
However, available data are insuffcient to fully assess the
environmental fate of naled.
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Ecoloa]cal Characteristics :
Currently available ecological effects studies on naled are
as tollows:
— Avian oral LD 50 ; 37—65 mg/kg
— Avian dietary LC 50 ; 2117—2724 ppm
— Freshwater fish LC 50 ; 160—900 ppb
— Acute LC 50 fresnwater invertebrates; 0.3 ppb
Based on studies available to assess hazards to wildlife
and aquatic organisms, naled is characterized as very high-
ly toxic to bees anc aquatic invertebrates. It is moder-
ately to highly toxic to fish and slightl toxic to upland
game birds and waterfowl. Insufficient data are available
to assess the toxicity of naled to estuarine and marine
organisms.
Label precautionary statements required by the Standard
snoulc reauce tr riazar to fish anc other wildlife.
After data gaps are filled, the potential hazards to ter-
restrial anc aquatic species will be better defined and
additional laDellnç reauirements may be imposed.
Efficacy review results : none conducted.
Tolerance Assessment :
The following tolerances are established for combined re-
sidues of naled and 2,2—dichiorovinyl dimethyl phosphate
(DDVP), expressed as naled, in or on raw agricultural com-
modities resulting from the application of naled formulations
to growing crops livestock, and poultry (40 CFR 180.125).
Commodity Tolerance (ppm )
Almonds (hulls, nut 0.5
Beans (dry, succuleri 0.5
Broccoli 1.0
Brussels sprouts 1.0
Cabbage 1.0
Cattle (tat, meat, meat 0.05
by—products)
Cauliflower 1.0
Celery 3.0
Citrus fruits (grapefruit, 3.0
lemons, oranges, tanger-
ines) -
Collards 3.0
Cottonseed 0.5
Cucumbers 0.5
Eggplant 0.5
Eggs 0.05
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Goats (fat, meat meat 0.OE
by—products)
Grapes 0.5
Grasses, forage 10.0
Hogs (fat, meat, meat 0.05
by—products)
Hops 0.5
Horses (fat, meat, meat 0.05
by—products)
Kale 3.0
Legumes, forage 10.0
Lettuce 1.0
Melons 0.5
Milk 0.05
Mushrooms 0.5
Peaches 0.5
Peas (succulent only)
Peppers 0.5
Poultry (fat, meat, meat 0.05
by—products)
Pumpkins 0.5
Rice 0.5
Safflower seed 0.5
Sheep (fat, meat, meat 0.05
by—products)
Spinach 3.0
Squash (summer, winter) 0.5
Strawberies 1.0
Sugar beets (roots, tops) 0.5
Swiss chard 3.0
Tomatoes 0.5
Turnips (tops) 3.0
Walnuts 0.5
All other raw agricultural 0.5
commodities except those
listed. (To account for
area pest (fly and
mosquito) control.)
The components of the residue metabolism in plants which
are of concern are naled and DDVP, and to a lesser extent,
organic bromide. Tolerances exist for combined residues
of nalea and DDVP (expressed as naled) and should continue
to reflect the concern for these two components.
The components of the residue from the metabolism in animals
which are of concern are the same as those in or on plants.
However, data on the metabolism or naled in poultry are
missing and this constitutes a data gap.
The Theoretical Maximum Residue Contribution (TMRC) is
1.1021 mg/day as naled, assuming a 1.5 kg diet, based on
the tolerances and food factors for all of the commodities
for which U.S. tolerances are established. No Acceptable
Daily Intake (ADI) or Maximum Permissible Intake (MPI)
figures have been established, due to the absence of
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acceptable toxicological data for naled. Reassessment
of the established naled tolerances must await receipt
and evaluation of the required data.
Although the Agency is unable to complete a tolerance
reassessment for naled because of a number of residue
chemistry and toxicology data gaps, the Agency has con-
cluded, based on available data, that no changes in
present tolerances are necessary at this time. The
Agency has also considered the residues of inorganic
bromide, resulting from the use of naled on crops and in
meat, milk, poultry and eggs, and does not anticipate
these residues to be of toxicological concern, and no
additional residue data on inorganic bromides are needed.
However, the Agency is concerned about organic brominated
metabolites of naled and its impurities. Accordingly,
additional data on this organic bromide in plants and
animals are being requested.
4. Summary of Regulatory Position and Rationale :
Use classification: not classified
Use restrictions: None
Unique warning statements required on labels:
The following environmental hazard statement must appear
on the manufacturing—use product labels:
This product is toxic to fish, aquatic invertebrates,
and wildlife. Do not discharge into lakes, streams,
ponds or public water unless in accordance with NPDES
permit. For guidance contact your regional office of
the Environmental Protection Agency.
Labeling changes to end—use products are not required by
the Standard, however, based on data reviewed by the
Agency the following statements will be required for
end—use products under the Agency’s Label Improvement
Program:
This product is toxic to fish, aquatic invertebrates,
and wildlife. Do not apply directly to water or wet-
lands. Runoff trom treated areas may be hazardous to
aquatic organisms in neighboring areas. Do not con-
taminate water by cleaning of equipment or disposal of
wastes.
This product is highly toxic to bees exposed to direct
treatmer t on blooming crops or weeds. Do not a ply
this product or allow it to drift to blooming crops
or weeds while bees are actively visiting the treat-
ment area. TM
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The following General Warnings and Limitations” state-
ments must appear on end—use product labels which bear
directions for aquatic use on food or feed crops:
Do not use with highly alkaline materials such as
lime or bordeaux mixture. Shrimp and crabs may also
be killed at application rates recommended. Do not
appply to tidal or marsh waters which are important
shrimp producing areas.
A reentry interval of 24 hours for the use of naled on
crops is required on end—use product labels containing
directions for use on crops.
The absence of reported fatalities from the Pesticide
Incidence Monitoring System (PIMS) report, taken in
conjunction with the apparent adequacy of medical and/or
emergency room treatment suggests an acceptably low
level or risk associated with incidental or accidental
exposure to naled prouccts.
Summary of risk/benefit review:
Dichlorvos (DDVP), a metabolite of naled was originally
referred to the Rebuttable Presumption Against Regis-
tration (RPAR) process because scientific studies indi-
cated that dichlorvos was mutagenic, might cause cancer,
nerve damage and birth defects in laboratory animals.
The RPAR Decision Document on Dichlorvos, was issued
September 30, 1982. It was concluded that the existing
evidence does not suppport the issuance of an RPAR for
dichlorvos and consequently, that an RPAR for naled as
a precursor of dichlorvos is also not warranted.
However, the Decision Document concluded that additional
data on carcino enicity and mutagenicity are needed to
complete the risk assessment for dichiorvos. Because the
data base was incomplete, dichiorvos was removec from the
RPAR process and returned to the registration process. A
Data Call—in Notice under FIFRA Section 3(c)(2)(B) was
issued March 23, 1983, requesting data on potential muta—
genic effects of dichiorvos be submitted by March 23, 1985.
Additionally, the Agency will wait until the ongoing
National Cancer Institue dichiorvos bioassy on carcino—
genicity is completed (currently scheduled for completion
in 1984) and evaluated prior to determining if additional
data on the carcinogenicity of dichiorvos will be req ired.
Since dichiorvos is a inetabolite of naled, evaluation of
these studies will be necessary for the completion of the
naled risk assessment.
No other human toxicological hazards of concern to the
Agency have been identified in studies reviewed tor the
Standard.
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5. Summary of Major Data Gaps :
Product chemistry: aata on the discussion of formation of
ingredients; preliminary analysis; certification of limits;
and analytical methods for enforcement of limits are the
major product chemistry data gaps.
Reeidue chemistry: additional data are required to support
the tolerances for beans (dry and succulent), broccoli,
BrusseLS sprouts, cabbage, cauliflower, celery, collards,
cottonseed, cucumbers, eggplant, eggs, grapefruit, hops,
kale, lemons, melons, mushrooms, oranges, pea forage,
peacheS peas, peppers, poultry (fat, meat, meat by-
products) pumpkins, soybean forage, spinach, straw-
berries, Swiss chard, tangerines, turnip tops, and
winter squash.
Data are required on residues in the processed products
of citrus (any member fruit), cottonseed, grapes, hops,
rice, and tomatoes. Data are also needed for turnip
roots. A tolerances must be established for this
commodity.
Toxicology: inhalation LC 50 , rat; 21—day dermai, rabDit;
90—day inhalation, rat; chronic toxicity, 2 species;
oncogenicitY, 2 species; teratogefliCity , 2 species;
reproduction, 2—generation rat; gene mutation; cnromosomal
aberration.
Reentry protection: toliar dissipation.
Wildlife and aquatic organisms: freshwater fish LC 50 (on
typical end—use product); acute LC 50 , freshwater inverte-
brates (on technical grade of active ingredient, and on
typical end—use product); acute LC 50 , estuarine and marine
organisms).
A].]. data must be submitted by June, 1986.
6. Contact person at EPA :
William H. Miller
Pro juct Manager (16)
insecticide—Rodenticide Branch
Registration Division (TS—767)
Environmental Protection Agency
Washington, DC 20460
Tel. (703) 557—2600
DISCLAIMER: The information presented in this Chemical
Information Fact Sheet is for informational purposes only
and may not be used to fulfill data requirements for pesticide
registration and reregistration.
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