uttioi ot Paiticidn ind Toxic Subcrincai
Environ mental Prot.c1.on	Wlc, of Pwiad. Progr.m, (TS-766C)
A9*lcv	Washington. DC 20460
*>ER*\ Pesticide
Fact Sheet
Name of Chemical: diazinon
Reason for Issuance: registration standard
Date Issued: December i 988
Fact Sheet Number: 96.1
1.	nreTRTFTICN CF chemical
Ccmron Name: Diazinon
Trade and Other Names: Spectracide, D.Z.N., Knox-Out
EPA Shaughnessy Codes: 057801
Chanical Abstracts Service (CAS) Number: 333-41-5
ENT Registry Rimber: 19507
Year of Initial Registration: 1956
Pesticide Type: Insecticide
Chanical Family: Organophosphate
U.S. and Foreign Producers: Ciba-Geigy, Trans Chanic Industries Inc. ,
and Makliteshim Agan (America) Inc.
Application: Aerosols, sprays, pet collars, ear tags, dips, ground
blast, aerial, and soil incorporation.
Annual Usage: 10 million pounds active ingredient (1985 data).
Predcminant Use(s): Agricultural, Heme and Garden uses.
Types of Fornulations: Dusts, enulsifiable concentrates, granules,
impregnated materials, liquids, microencapsulated, pressurized
sprays, soluble concentrates, wettable pewders.

Sunmarv Science Statanent
Diazinon is not oncogenic in the Fisher F344 rat or in the B6C3F1 mouse.
Diazinon does not induce developmental toxicity in rats or rabbits at dose levels
up to and including 100 mg/kg/day (highest dose tested).
Based on acceptable laboratory data, technical diazinon is characterized as
very highly toxic to waterfowl on an acute oral basis, with an LD50 of 6.38 mgAg
for mallard ducks. Avian dietary studies characterized diazinon as highly toxic
to upland game birds with a dietary LC50 of 245 pptn for bobwhite quail.
Supplemental data characterize diazinon as very highly toxic to waterfowl with a
dietary LC50 of less than 47 ppn for mallard ducks. End-use formulations of
diazinon are characterized as very highly toxic to waterfowl, upland game birds
and songbirds on acute oral and dietary basis. Technical diazinon and its end-
use fonrulations are characterized as very highly toxic to aquatic organisms.
It is considered highly toxic non-target insects.
Diazinon degrades rapidly under aerobic, anaerobic, aquatic anaerobic and
sterile soil conditions. Microbial degradation appears to be the major pathway
for the degradation of diazinon. Hie most probable mechanism responsible for
degradation under sterile and anaerobic soil conditions appears to be chemical
hydrolysis in acidic soils. Supplemental hydrolysis data indicate that diazinon
is stable with respect to hydrolysis at pH 7 and 9 but hydrolyzes in non-sters
water with a pH of 5.
The major soil degradate is oxypyrimidine. Oxypyrimidine is more persistent
than diazinon under aerobic and sterile, anaerobic and anaerobic aquatic soil
Diazinon with a 4 day EC50 of 4.14 mg/L and a 7 day ET50 of 3.7 mg/L is
characterized as being moderately toxic to freshwater green alga. Diazinon
caused greater than 25% detrimental effect in plant vigor in tomatoes, cucumbers,
onions, and carrots. Diazinon caused a greater than 25% detrimental effect in
seed germination in oats, tomatoes, and carrots. No detrimental effect was seen
for seedling emergence.

Ownical Qiaractjeristics of the Technical
Riysical State: Liquid
Color: Airiber and brown
Odor: Mild, sweet, and aromatic
MDlecular Weight and Fomtila: (304.3) C12H21N23PS
Boiling Point: 83-84*: at 0.002 mm Hg
Vapor Pressure: 1.4 x 10_4nm at 20^
Density: 1.12 g/ml at 20C
Solubility in various solvents: In petroleum oils, 60 ppn in water at
25C and 40 ppn in water at 20c.
^^^^^1^^	xsLics
Acute Oral: LD50= 618 rag/Tog*
Acute Dermal: UD50 > 2000 mg/)cg*
Primary Dermal Irritation: Not-irritating*
Primary i^e Irritation: Non-irritating*
Dermal Sensitization: Positive response in 10% of the human volunteers
Acute Inhalation: LC50=3.5 mg/L*
Acute Delayed neurotoxicity: Data gap
Subchroriic toxicity: Data gap
Oncogenicity: {mouse and rat) Not oncogenic
Chronic Feeding: Data gap
Metabolism Data gap
Teratogenicity: (Rabbit and Rat) No developmental toxicity at doses up to
and including 100 mg/kg/day.
* This information may not be applicable to all currently registered
manufacturing use products (MUPs) of diazinon. The Agency is requiring
additional toxicity studies to determine the toxicological similarities
or dissimilarities of the registered MUPs.

Reproduction: Data gap
Mutagenicity: Data gap
Maior routes of exposure
Dermal, oral and inhalation
Rivsiolocrical and Biochemical Qiaracteristics
Mechanism of Pesticidal Action: Cholinesterase Inhibition
Metabolism and Persistence in Plants and Animals: Data gap
Envircumental Characteristics
Diazinon degrades rapidly under aerobic, anaerobic, aquatic anaerobic and
sterile soil conditions. The major soil degradate is oxypyrimidine.
Oxypyrimidine is more persistent than diazinon under aerobic and sterile,
anaerobic and anaerobic aquatic soil conditions. Diazinon's potential to
contaminate groundwater is unkncwn.
Ecological Characteristics
Avian acute toxicity:
3.2	mg/kg (Red-winged blackbird)-Very highly toxic
6.3	mg/kg (Mallard duck)	-Very highly toxic
10 mg/kg (Botwhite quail)	-Very highly toxic
Avian dietary toxicity:
< 47 ppn (Mallard duck)	-Highly toxic
245 ppn (Bobwhite quail)	-Highly toxic
Freshwater fish acute toxicity:
Want-water DC50 = 136 ug/L (Bluegill sunfish) -Highly toxic
Coldwater DC50 = 90 ug/L (Rainbow Trout) -Very highly toxic
Marine fish acute toxicity:
LC50 = 1400 ug/L (Sheepshead minnow) -{"tiderately toxic
Freshwater invertebrate toxicity:
1X50 = 0.2 mg/L (QanroaEUS fasciatus)-Verv highly toxic
Marine invertebrate toxicity: Data gap
Non-Target Insects:
LD50 =0.22 ug/bee (contact: Honey Bees)-Highly toxic
LD50 = 0.2 ug/bee (oral: Honey Bees) -Highly toxic

Tolerances have been established for residues of diazinon in a variety of
raw agricultural commodities, in meat, fat arid meat byproducts (40 CFR
180.153), food additives (40 CFR 185.1750) ana in food handling estab-
lishments (40 CFR 185.1750), and feed handling/processing establishments
(40 CFR 186.1750). Itolerances for residues of diazinon are currently
expressed as residues of diazinon ESC S-
Codex FRL's, Canadian, and Mexican tolerances have been established for
many of diazinan*s registered uses. Compatibility of these tolerances to
that of U.S. tolerances cannot be determined until all additional metabolism
and residue studies are available.
Based chi inhibition of plasma cholinesterase observed in a 90 day rat
feeding study a NCXL of 0.009 mg/kg/day was established. A provisional
acceptable daily intake (FM)I) has been established at 0.00009 mgAg/day
utilizing an uncertainty factor of 100. *me FM)I is provisional because the
existing data base on diazinon is lacking chronic feeding studies, and a
multi-generation reproduction study.
4. Required Unique Labeling
o Restricted use Statement for all commercial outdoor
uses (e.g., turf, and agricultural).
o Restricted use Statement for residential products in toxicity category
I or II,(danger or warning).
o Homeowner Protection Statements for indoor and outdoor
o Institutional use Protection Statements for hospitals and schools.
o Feed and Food Handling Establishments statements.
o Worker Protection Statanents for Toxicity Categories I, II and III end-
use formilations.
o 24-Hour Interim Reentry Interval (ccnmercial and greenhouse use).

5. Sunroarv of Regulatory Positions
o The Agency is deferring a decision at this time on whether to place diazinon
into Special Review for its potential hazard to avian species resulting fran its
use on agricultural crops, cm turf and other grassy sites (e.g., athletic fields,
recreational parks, home lawns).
o Hie Agency is classifying all conmercial outdoor uses (agricultural crops,
ornamentals, and turf) of diazinon for restricted use, based upon its known
toxicity to birds and aquatic species.
o All diazinon aid-use products that are in Tbxicity Category I or II (IWCER or
WAPNING) and bear product labeling that directly recommends residential use or
reasonably can be interpreted to permit residential use are classified for
restricted use. Such products may be used only by certified applicators or
persons under their direct supervision. In the past, the Agency has allowed
these types of products to be labeled , "For Agricultural Use Only" or "For FCO
Use Only" in an attempt to limit use to conmercial or trained applicators.
However, these statemaits are unenforceable.
o The Agency will is requiring the following testing of a series of typical
end use products: acute oral, acute dermal, primary dermal irritation, primary
eye irritation, dermal sensitization, and acute inhalation if appropriate. The
Agency will reserve alternative product formulations testing, pending submission
and review of toxicity testing on the stabilized technical diazinon products
(manufacturing use products).
o The U.S. Fish and Wildlife Service, Division of Endangered Species and Habitat
Conservation (DESCH) has determined that certain uses of diazinon, including uses
on corn and sorghun may jeopardize the continued existence of endangered species.
Based on this determination, BESHC specified reasonable and prudent alternatives
to avoid jeopardizing the continued existence of the identified species by these
uses. EFA is developing a program to reduce or eliminate exposure to these
species to a point where use does not result in jeopardy. PR Notices 87-4 and
87-5, which specified labeling requirements designed to reduce or eliminate
exposure to endangered species, have been withdrawn. The Agency will issue a
notice of arty necessary regulatory actions when the program is developed.
o The Agency will require each registrant of a manufacturing use product to
submit the following toxicity studies on their current fonrulations: acute oral,
acute denial, acute inhalation, primary dermal irritation, primary eye
irritation, dermal sensitization, and a 6-week rat feeding study. The Agency may
require additional toxicity testing based upon its evaluation of these studies.
o The Agency will iupose a 24-hour interim reentry interval for all conmercial
uses of diazinon (greenhouses, agricultural).
o The Agency is revising worker safety and protective equipment statements for
end use products containing diazinon.

o The Agency is not imposing a ground water contamination advisory statement for
diazinon products at this time. The Agency will assess the potential of diazinon
for groundwater contamination after receipt and review of environmental fate data
and will determine whether regulatory action is necessary.
o The Agency is inposing additional statements for all end-use products intended
for use in and around the heme.
o The Agency has determined that diazinon products must bear revised and updated
labeling for hazards to norrtarget species.
o The Agency will propose tolerance revocation for rutabagas, red chicory tops,
and dandelions (40 CFR 180.153).
o Residue data must be sutmitted and tolerances must be proposed for corn fodder
and forage, and either sorghum forage and fodder, or wheat forage, hay and straw,
and soybean straw and hay.
o For the following crops; sorghum fodder and forage, soybean straw ar*3 hay, and
sugarcane forage, the registrant is given the choice of developing and submitting
data in support of tolerances, or of adding label restrictions aganist the
feeding and grazing of treated crops to livestock. Each registrant most inform
the Agency by 90 days of receipt of this Registration Standard which option he
chooses. If he selects the label restrictions, labeling sutmitted at the 9 month
deadline must include the grazing/feeding restrictions.
o The Agency will not grant any significant new tolerances or any sigificant new
food uses for diazinon until the required residue chemistry and toxicology
studies have been sutmitted and reviewed.
o The Agency is not requiring additional residue data to support the established
tolerances for diazinon in or on guar beans and coffee beans.
o The Agency will revise caimodity definitions for certain raw agricultural
ccmrodities listed in 40 CFR 180.153.
a)	Tolerance listing "peas with pods (determined on peas after renoving any
shell present when marketed)" will be revised to read, "peas, succulent".
b)	Tolerance listing "bean forage" will be revised to read, "bean vines".
c)	the tolerance listing for "wheat forage and straw" was omitted frcm
listing and will read "wheat forage and straw 0.05 ppn".
o The connon name "diazinon" will appear before the chenical name on the
pesticide label, rebels must be revised to reflect this.
o Petroleum distillates and xylene based solvents mast be declared as inert

o The Agency has identified certain data that will receive inmediate review wi
158.240 Residue Chemistry
-	Plant and Animal Metabolism
-	Special Storage Stability (EUP)
158.290 Environmental Fate
-	Hydrolysis
-	Fhotolysis
158.340 Toxicology
-	Acute Toxicity Studies (MUP)
-	6 week Feeding study (MUP)
-	Neurotoxicity study (MUP)
-	Acute Toxicity Studies (HP)
158.490 Ecological Effects (all)
6. Sumarv of Maior Data Gaps	Timeframe Ranges
Toxicology	12-50 Months
BTvirormental Fate/Exposure 9-39 Manths
Ecological effects 9-30 Months
Residue Chemistry	18-24 Months
prnrftv-f 9-12 Months

7. gamer fepxn at eta
George LaRocca
Product Manager (15)
Insecticide Rodenticide Branch
Registration Division (TS-767C)
Office of Pesticide Programs
Elrviromental Protection Agency
401 M Street, S. W.
Washington, D. C. 20460
Office location and telephone ntsnber:
Roan 204, Crystal Mall #2
1921 Jefferson Davis Hi^way
Arlington, VA 22202
(703) 557-2400
DISCLAIMER: Bie information in this Pesticide Fact Sheet
is a summary only and is not to be used to satisfy data
requirements for pesticide registration and reregistration.
Hie ccnplete Registration Standard for the pesticide may be
obtained fran the National Technical Information Service.
Contact the Product Manager listed above for further