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diazinon (D.Z.N., Spectracide) EPA Chemical Fact Sheet 9/86

EPA Pesticide
Fact Sheet

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)
                phosphorothioate
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 
aquatic invertebrates.


          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 
comments.

     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 
appropriate action.


                 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
EPA
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.

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