diazinon (D.Z.N., Spectracide) EPA Chemical Fact Sheet 9/86
Name of Chemical: Diazinon
Reason for Issuance:
Date Issued: September, 1986
Fact Sheet Number: 96
1. DESCRIPTION OF CHEMICAL
Chemical name: O,O-Diethyl 0-(2-isopropyl-6-methyl-4-pyrimidinyl)
Common name: Diazinon
Trade name: Spectracide, AG500, Alfa-tox, Sarolex, D-Z-N Diazinon 14G,
Geigy Spectracide Lawn and Garden Insect Control, etc.
EPA Shaughnessy code: 057801
Chemical abstracts service (CAS) number: 333-41-5
Year of Initial Registration: 1952
Pesticide type: Insecticide
Chemical family: Organophosphate
2. USE PATTERNS AND FORMULATIONS
- Application sites: Field, fruit, nut, vegetable (including seed
treatment) and nonfood crops (ornamentals and tobacco); forestry
(including Christmas tree plantations); greenhouse food crops
(vegetable bedding plants and ornamentals); livestock; range,
pasture, and grassland; animal premises; lawns and turf; domestic
outdoor and indoor, (household); commercial indoor (including
food handling establishments and processing plants); commercial and
industrial outdoor sites.
-.Types of formulations: Wettable powder, wettable powder/dust,
emulsifiable concentrate, dust, microencapsulate, soluble
concentrate, granular, oil solution, aerosol spray, spray
concentrate, impregnated materials, soluble concentrate, liquid
ready-to-use, and pressurized liquid.
- Types and methods of application: Ground, aerial, and those methods
unique to the formulation, such as aerosols.
3. SCIENCE FINDINGS
Physical and Chemical Characteristics -
- Physical state: Liquid
- Color: Colorless (Technical is amber to brown)
- Odor: Typical of organophosphates
- Boiling point: 83-84 degrees C
- Melting point: Not applicable
- Flash point: 82 degrees F for AG500
' >105 degrees F for 4E and 4S
- Human Toxicology Characteristics -
- Acute rat oral LD50: 66-635 mg/kg for females and 96-967 mg/kg for
males, Toxicity Category II
- Acute rabbit Dermal LD50: >2,000 mg/kg, Toxicity Category III
- Acute rat inhalation LD50: 3.5 mg/l, Toxicity Category III
- Dermal rabbit irritation: Toxicity Category IV
- Eye rabbit irritation: data gap
Ecological characteristics -
- Hazards to aquatic invertebrates and wildlife:
Avian subacute dietary LC50 (ppm)
191 for Mallard Ducks
245 for Bobwhite Quail
Avian acute oral LD50 (mg/kg)
3.5 for Mallard ducks
10 for Bobwhite Quail
These values characterize diazinon as very highly toxic to birds.
Aquatic invertebrate LC50
0.079 ppm for bluegill sunfish
0.635 ppm for rainbow trout
0.522 ppb for Daphnia sp.
These values characterize diazinon as very highly toxic to fish and
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
On January 15, 1986, a FEDERAL REGISTER Notice was published
concerning the Special Review of all pesticide products containing
diazinon registered for use on golf courses and sod farms. The Special
Review was based on the hazard to non-target birds from diazinon's use
on these two sites. The Notice announced (l) the initiation of the
Special Review on these two sites, (2) the Preliminary Determination
proposing to cancel registrations and deny applications for diazinon
products used on these two sites, and (3) the availability of the
Support Document. The Support Document contained a risk/benefit
analysis, which was the basis for the Agency's action.
In evaluating the hazard to birds, the Agency considered (l) acute
toxicity studies which indicated that diazinon is very highly toxic to
birds, (2) residue level and dose estimates on grass and seed which
indicated a potential hazard, and (3) bird kills reported to the Agency
in which diazinon was either confirmed or implicated as the primary
cause. These kills have involved 23 species of birds and occurred
throughout the country and throughout the year.
The Agency's concern for the hazard to non-target birds included a
concern for the impact on populations of species at risk. The Agency
reviewed information which indicated that diazinon caused a reduction of
a local population of Atlantic Brant Geese when applied according to
label directions to a golf course in New York.
The Agency also reviewed information concerning the avian and human
hazards of the five major alternatives. Based on a comparative avian
hazard assessment, the Agency determined that the major alternatives are
not likely to be of greater hazard to birds than diazinon. Based on the
available data concerning the hazard to humans, the Agency determined
that the alternatives do not appear to pose a greater human health
hazard than diazinon.
In the Support Document the Agency also reviewed the benefits of
diazinon on golf courses and sod farms. Estimates indicate that at
least 512,000 pounds are used per year on golf courses and 60,000 pounds
on sod farms. The impact of cancellation that results would be a cost
increase of $937,200 for golf courses and $300,000 for sod farms. The
Agency anticipates that these impacts would be minor when compared to
the maintenance cost of $1,900,000,000 for golf courses and the gross
revenue of $210,000,000 on sod farms.
In weighing risks and benefits, the Agency reviewed a number of
options to reduce the risk to birds. However, the Agency determined
that cancellation was the only option that would reduce the hazard to
birds adequately. The Agency concluded that the risks outweigh the
benefits and proposed cancellation of all products registered for use on
sod farms and golf courses.
During the comment period that followed publication of the FEDERAL
REGISTER Notice, the Agency received additional information on the
hazard to birds, which included reports of 26 additional bird kills.
These kills once again confirm that the hazard from diazinon is
widespread throughout the country and throughout the year. In addition
the Office of Endangered Species, U.S. Department of the Interior,
commented that certain endangered species could be seriously affected by
the use of diazinon on golf courses and sod farms.
The Agency also received data concerning diazinon residues on grass
and effects on Canada Geese penned on turf. The data demonstrated that
birds foraging on treated turf would be exposed to lethal diazinon
residues within a very short period of time and that these residues
would be high enough to cause death to foraging waterfowl.
During the comment period the Agency also received information
regarding the benefits of diazinon use, which included efficacy data on
diazinon and its alternatives. The results indicated that the efficacy
of the major alternatives is about the same as diazinon.
The Office of Pesticide Programs (OPP) transmitted the Support
Document to the Scientific Advisory Panel (SAP) and the U.S. Department
of Agriculture (USDA). The SAP's comments supported the Agency's
conclusions concerning the avian hazard from diazinon application to
golf courses and sod farms. The USDA commented that the proposed
cancellation action was premature and could be inappropriate. The
FEDERAL REGISTER Notice responds point-by-point to each of their
The Agency also received 96 comments during the public comment
period, most of which supported the proposed action.
The Agency carefully reviewed all of the new information and all
of the comments that were submitted. The Agency still concludes that
the hazard to birds from diazinon use on golf courses and sod farms
outweighs the minor benefits and that cancellation is the only
5. SUMMARY OF MAJOR DATA GAPS
The Agency is concerned about the hazard to birds from diazinon use
on other sites. The data base is inadequate to evaluate the hazard on
all of the remaining sites at this time. Consequently, the Agency is
requiring the data necessary to fully evaluate this problem through the
reregistration process. A Registration Standard is scheduled to be
completed by the end of this year.
6 . CONTACT PERSON AT EPA
Ingrid M . Sunzenauer
Office of Pesticide Programs
Registration Division (TS-767C)
401 M Street, S.W.
Washington, D.C. 20460
DISCLAIMER: The information in this Chemical Information Sheet is for
informational purposes only and may not be used to fulfill data
requirements for pesticide registration or reregistration.