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phosalone (Zolone) EPA Pesticide Fact Sheet

EPA Pesticide Fact Sheet
Name of Chemical:  PHOSALONE
Date Issued:
Fact Sheet Number:

                       1. DESCRIPTION OF CHEMICAL

- Generic Name:  S-6-chloro-2,3-dihydro-2-oxobenzoxazol-3-yl-methyl
  (Chemical)      O,O-diethyl phosphorodithioate
- Common Name:  Phosalone (ANSI)
- Other Chemical Nomenclature:
  - S-[(6-chloro-2-oxo-3(2H)benzoxazolyl)methyl] O,O-
  - O,O-diethyl phosphorodithioate S-ester with 6-chloro-
  - O,O-diethyl-S-[(6-chloro-2-oxobenzoxazolin-3-yl)
  - S-[6-chloro-3-(mercaptomethyl)-2-benzoxazolinone]
  - O,O-diethyl-S-[6-chloro-3-(mercaptomethyl)-2-benzoxazolinone]
- Trade Names:  Azonfene, Benzofos, RP11974, Rubitox, and Zolone.
- EPA Shaughnessy Code:  097701
- Chemical Abstracts Service (CAS) Number:  2310-17-0
- Year of Initial Registration: 1974
- Pesticide Type:  Insecticide/Acaricide
- Chemical Family:  Organophosphate
- U.S. and Foreign Producers:  Rhone-Poulenc, Inc.


- Application Sites: Nut crops, citrus crops, pome fruits, stone fruits,
  grapes, potatoes, artichokes, roses, and arborvitae.
- Formulation Types:  Technical, Emulsifiable Concentrate and Wettable
- Application Methods:  Foliar: ground and aerial application.

                  3.  SCIENCE FINDINGS

Summary Science Statement

     Phosalone may have an adverse impact on birds and aquatic organisms 
resulting from all use patterns, excluding ornamentals.  Aquatic and 
terrestrial field studies are required to determine the potential risks 
to these organisms.  Laboratory data show that technical phosalone is 
highly toxic to fish and aquatic invertebrates.

     The toxicological profile of the end-use products places them in 
Toxicity Category II for primary eye irritation, acute oral and dermal 
exposures.  The end-use products were only mildly irritating to the skin 
when tested for dermal irritation.  The products were characterized as 
weak dermal sensitizers.  Phosalone can cause adverse effects to persons 
entering treated fields and to persons involved in the preparation and 
application of this pesticide.  Preliminary data show that groundwater 
contamination is unlikely, but the Agency is unable to conduct a full 
assessment due to data gaps.

Chemical/Physical Characteristics of the Technical Material

- Physical State:  Crystalline solid
- Color:  White
- Molecular weight and formula:  367.8 gms-Cl2H15ClN04P52
- Melting Point:  45-47 degrees C
- Density:  1.391 g/ml at 20 degrees C
- Vapor Pressure: less than or equal to 0.5 x 10-6 mm Hg at 24 degrees C
  and 16.4 x 10-6 at 60 degrees C
- Solubility:  At 20 degrees C: 1.7ppm in water; 20 g/100 ml in methanol
  and ethanol, and 10g/100ml in acetone, benzene, cyclohexanone,
  acetonitrile, xylene, toluene, dioxane, chloroform, and methyl
- Stability:  Very stable under normal laboratory conditions for a
  period of 2 years.

Toxicology Characteristics (Technical Material)

- Acute Oral:  Toxicity Category II (90 and 125 mg/kg in female and male
  rats respectively).
- Acute Dermal:  Toxicity Category II ( LD50 > 350 mg/kg for both males
  and females).
- Acute Inhalation:  Waived for technical, particles analyzed were
  determined not to be within the respirable range (less than or equal
  to 15 microns).
- Primary Dermal Irritation:  Toxicity Category IV (PDIS-0.77, mildly
  irritating to intact and abraded skin).
- Primary Eye Irritation:  Data gap.
- Skin Sensitization:  Data gap.
- Delayed neurotoxicity:  Negative in hens.
- Subchronic Oral (non-rodent):  Data gap.
- Oncogenicity: Data gap.
- Chronic Feeding: NOEL for RBC inhibition in the rat is 25 ppm.
- Metabolism:  Data gap
- Teratogenicity:  Data gap
- Reproduction:  Data gap
- Mutagenicity:  Data gap for point mutation assay in mammalian cells,
  structural chromosomal aberration, and other genotoxic effects.
- Major routes of exposure:  Dermal and respiratory exposure to mixers,
  loaders, applicators, and fieldworkers.

Environmental Characteristics

     Phosalone is stable at pH 5 and 7, but is hydrolyzed at a pH of 9 
with a half-life of 9 days.  Artificial light accelerated degradation in 
buffered solution at a pH of 5 and in soil.  Aerobic soil metabolism 
studies demonstrate half-life values of 1-7 days.  Field dissipation 
studies showed half-life values of 1-9 weeks.  Phosalone was essentially 
immobile in a soil column test.  Based upon this preliminary data 
phosalone appears unlikely to contaminate ground water.  It exhibited 
moderate accumulation in the bluegill sunfish, with rapid dissipation in 
untreated waters.

Ecological Characteristics (Technical grade)

- Avian Oral Toxicity:  Slightly toxic to waterfowl (acute oral toxicity
  value: mallards > 2150 mg/kg).
- Avian Dietary Toxicity:  Slightly toxic to waterfowl and upland-game
  (8 Days)                 birds (subacute toxicity values:
  mallards 1659 ppm and bobwhite quail 2033 ppm).
- Freshwater Fish Acute:  Very highly toxic to warmwater fish and 
  Toxicity (96-Hours)     and highly toxic to coldwater fish (acute
  LC values: 0.05 ppm bluegill and 0.63 ppm rainbow trout).
- Freshwater Invertebrate: Very highly toxic to aquatic invertebrate
  Toxicity (48-Hours)      (acute EC value: 0.0012 ppm Daphnia magna)

                    4. TOLERANCE REASSESSMENT

     Tolerances have been established for phosalone on a variety of raw 
agricultural commodities, in meat, fat and meat byproducts (40 CFR 
180.263) and in processed food (21 CFR 193.340) and feed (21 CFR 

     Tolerances for the following commodities are adequately supported: 
potatoes, citrus, apples, pears, apricots, cherries, nectarines, 
peaches, plums (fresh prunes), dried prunes, tree nuts, almond hulls, 
grapes, raisins, artichokes, and the fat, meat, and meat byproducts of 
cattle, goats, hogs, horses and sheep.

     Additional data are required to assess the need for food/feed 
additive tolerances for the following products processed from raw 
agricultural commodities bearing measurable, weathered residues: potato 
granules or flakes, chips, and wet and dry peels, raisin waste and grape 

     The nature of the residues in both plants and animals are not 
adequately understood.  If, on receipt of the required metabolism data, 
the Agency determines that residues in addition to the parent require 
regulation, additional methods for data collection and enforcement may 
be required.

     Crop group tolerances may be proposed for the Pome Fruit Group at 
10 ppm and for the Stone Fruit Group at 15 ppm.

     The Agency has established a Provisional Acceptable Daily Intake 
(PADI) at 0.0025 mg/kg/day based on a 6-month dog feeding study in which 
plasma cholinesterase activity was depressed.  Because a NOEL was not 
established in this study a 100 fold uncertainty factor has been used 
rather than the 10 fold factor normally applied for cholinesterase 


- Phosalone is not being placed into Special Review at this time.
  Although the Agency is concerned about the potential adverse impact of
  phosalone on birds and aquatic organisms resulting from the
  agricultural use patterns, aquatic and terrestrial field studies are
  needed in order to evaluate the potential risks to these species.
- The Agency has sufficient data (analysis of pesticides with similar
  uses were found to be in jeopardy) to indicate that the current use
  patterns of phosalone may affect endangered species.  Endangered
  species labeling is reserved pending concurrence from the Fish and
  Wildlife Service.
- The Agency is classifying all Phosalone end use products as Restricted
  Use Pesticides; except for products packaged and labeled solely for
  use around the home.  Products containing phosalone for use on
  cherries and citrus are restricted due to avian hazards.  All use
  patterns are restricted due to aquatic toxicity.  The estimated
  environmental concentrations exceed the LC50 value for fish and the
  EC50 value for aquatic invertebrates, and the NOEL values for avian
- The Agency is imposing a 6-month rotational crop restriction for small
  grains and a 12-month rotational crop restriction for leafy vegetables
  and root crops.
- No significant new tolerances or new food uses will be granted until
  the Agency has received sufficient data to evaluate the dietary
  exposure of phosalone.
- The Agency will retain the 24-hour reentry interval imposed in the
  1981 Registration Standard.  This reentry interval will be retained
  until the required reentry data are received and evaluated.  Data
  will be reviewed on a priority basis because of reported poisoning
  incidents in California.
- The Agency will require that end use products bear label statements to
  protect mixers, loaders, applicators, flaggers, and fieldworkers.
- Preliminary data indicate that groundwater contamination is unlikely.
  The Agency is requiring environmental fate studies to fully
  characterize phosalone's fate in the environment.


Toxicology                                          Time Frame

Primary Eye Irritation                                9 Months
Dermal Sensitization                                  9   "
Acute Inhalation                                      9   "
Subchronic oral toxicity--Dog (for cholinesterase    12   "

Oncogenicity--rat                                    50   "
Teratogenicity--(rat and rabbit)                     15   "
Reproduction--(rat)                                  39   "
Mutagenicity                                         12   "
Metabolism study                                     12   "
Dermal Absorption (rat)                               9   "

Environmental Fate/Exposure

Aged leaching study                                  12   "
Rotational Crop (Confined)                           12   "
Foliar dissipation study                             15   "
Spray Drift                                          12   "
Soil Dissipation                                     27   "

Fish and Wildlife

Avian reproduction                                   24 Months
Actual field testing- birds and mammals (citrus)     30   "
Simulated or Actual field testing-aquatic organisms  48   "
Acute toxicity to Estuarine and Marine organisms     12   "
Fish early life stage and aquatic invertebrate
   life cycle                                        15   "
Acute toxicity to Freshwater Invertebrate             9   "

Residue Chemistry

Animal and Plant metabolism                          18 Months
Storage stability                                    15   "
Processing studies for potatoes and grapes           24   "
Residue data (tea)                                   18   "

Product Chemistry                                  6-15 Months

                   7.  CONTACT PERSON AT EPA

Dennis H. Edwards, Jr.
Product Manager (12)
Insecticide-Rodenticide Branch
Registration Division (TS-767C)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street, S. W.
Washington, D. C.   20460

Office location and telephone number:
Room 211, Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA   22202
(703) 557-2386

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.