### UNITED STATES ENVIRONMEN TAL PROTECTION AGENCY WASHINGTON, DC 20460

OFFICE OF PREVENTION, PESTICIDES, AND TOXIC SUBSTANCES



### Memorandum 04/26/10

Subject: 2,4-XYLENOL:PRODUCT CHEMISTRY/
ENVIRONMENTAL FATE AND ECO-EFFECTS SCOPING
DOCUMENT

From: A. Najm Shamim, PhD, Chemist Regulatory Management Branch2 Antimicrobials Division (7510P)

To: Eliza Blair, CRM for 2,4-Xylenol Regulatory Management Branch2 Antimicrobials Division (7510P)

Through: Mark Hartman, Chief Regulatory Management Branch2 Antimicrobials Division (7510P)

And Nader Elkassabany, PhD, Chief Risk Assessment & Science Support Branch Antimicrobials Division (7510P)

RR Case Name PC Codes CAS # 2,4-Xylenol 86804 105-67-9

RR Case #: 4098

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### TABLE OF CONTENTS

2,4-XYLENOL: PRODUCT CHEMIS TRY/ ENVIRONMENTAL FATE
AND ECO-EFFECTS SCOPING DOCUMENT PAGE

No.

2,4-XYLENOL............................................

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APPENDICES--------------------------------

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REGISTRATION REVIEW DOCUMENT

PRODUCT CHEMISTRY, ENVIRONMENTAL FATE AND ECOLOGICAL EFFECTS SUMMARY FOR 2,4-Xylenol

PCCode:86804 Case No. 4098

Chemical name Use patterns/use sites 2,4-Xylenol A Ready to use flowable emulsion for control of crown gall, burr and
olive bacterial diseases on certain fruit and nut trees, vines, ornamentals. Non-edible organs only

Regulatory History

2,4-Xylenol was registered by the Agency for use in the United States in 1980 It is used to control bacterial diseases like crown gall, burr, and olive knot on certain fruit and nut trees, vines, and ornamentals. The use is ve ry limited to a few sites, and amount of the active present is at 0.466% in water/kerosene mixture and is applied by paint brush as a spot treatment to roots or stem/bark. At present only one product is registered and it contains two activ es: 2,4-xylenol and mcresol

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### Table 1: Registered Active Products for 2,4-Xylenol

EPA Reg.

Number Product Name Formulation Type % Active Ingredient Registrant

40230-2 Gallex Ready-to-use

Flowable
Emulsion 0.466 AgBioChem, Inc



### Table 2. Chemical Identity

Common Name 2,4-Xylenol

Chemical Name 2,4-dimethylphenol

IUPAC 2,4-dimethylphenol

Molecular Weight 122.17

PC Code 86804 CAS Registry Number 105-67-9

Molecular Formula C 8 

### H 10 

### O Registration Review Case No. 4098

Registration Review Case Name 2,4-Xylenol

Classification: Organic

Structure:

Science Findings:

A few data gaps for each discipline are noted below.

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### Product Chemistry Summary

Table 3: Physical and Chemic al Properties of 2,4-Xylenol

Guideline

No. Physical and Chemical Properties Value

830.1550 Product identity and composition Refer to Table 2

830.1600 Description of materials used to produce the product CBI

830.1620 Description of production process CBI

830.1650 Description of formulation process CBI

830.1670 Discussion of formation of impurities CBI

830.1700 Preliminary analysis CBI

830.1750 Certified limits CBI

830.1800 Enforcement analytical method No data

830.1900 Submittal of samples CBI

830.6302 Color White 1

830.6303 Physical State Crystalline solid 1

830.6304 Odor Phenolic odor 1

830.6313 Stability to sunlight, normal and elevated temperature No data

830.6314 Oxidation/Reduction: Chemical Incompatibility No data

830.6315 Flammability

Flash Point No data

830.6316 Explodability No data

830.6317 Storage Stability No data

830.6319 Miscibility No data

830.6320 Corrosion Characteristic No data

830.6321 Dielectric breakdown voltage No data

830.7000 pH No data

830.7050 UV/Visible absorption spectra No data

830.7100 Viscosity No data

830.7200 Melting Point 26 o C 1

830.7220 Boiling point 211 o C at 760 mm Hg 1

830.7300 Density 0.97 g/cc at 20 o C 1

830.7370 Dissociation Constants in water 10.63 at 25 o C 1

830.7520 Particle size Not applicable

830.7550 Octanol/water partition coefficient (K OW ) (Log K

ow ) 2.35 1

830.7840 Solubility in water 0.62/100 ml in water; miscible in alkaline

solutions 1 ; 830-7840 Solubility in organic solvents in g/100

ml Freely soluble in alcohol, chloroform, benzene and

ether

830.7950 Vapor pressure 0.2 mm Hg at 25 o C 1



### Note: 1) The data in Table 3 are reported in the Agency’s Reregistration Eligibility Decision RED on 2,4-Xylenol and m-Cresol ( RED, 1994)

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### Environmental Fate and Transport Data Summary: EPA’s Reregistration Eligibility Decision (R ED,1994) waived all environmental fate and transport data for this chemical because the us e is very limited to a few sites as noted above, and amount of the active is at 0.466% in water/kerosene mixture and is applied by paint brush as a spot treatment to roots or stem/bark. Based on EPA’s EPI Suite (Estimation Model Program) for product chemistry, ecological and fate parameters), BIOWIN1 (linear model) and BIOWIN2 (non-linear model) predict that 2,4-xylenol will biodegrade fast u nder aerobic conditions, while BIOWIN7 Model estimates that it will not biodegrade fast under anaerobic conditions. The exposure to this chemical is likely to be minimal. However the Agency would require the following fate data to ascertain the stability of this chemical:

o (GLN 835.2120): Hydrolysis:

The studies must be conducted on the pure 2,4-Xylenol and not on the mixture used in the end-use product formulation.

Ecological Effects Data Summary:

EPA’s Reregistration Eligibil ity Document ( RED,1994) waived all environmental fate and transport data for this chemical because the use is very limited to a few sites as noted above, and amount of the active is at 0.466% in water/kerosene mixture and is applied by paint brush as a spot treatment to roots or stem/bark. The exposure to this chemical is likely to be minimal. However the Agency would require the following fate data, if the hydrolys is study shows that 2,4- Xylenol is stable

* GLN 850.2100 Acute avian oral

* GLN 850.2200 Acute avian dietary, bobwhite quail * GLN 850.1075 Acute fish, rainbow trout * GLN 850.1010 Acute aquatic invertebrate, Daphnia Magna

The studies must be conducted on the pure 2,4-Xylenol and not on the mixture used in the end-use product formulation.

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### BIBLIOGRAPHY FOR: PRODUCT CHEM ISTRY, ENVIRONMENTAL FATE AND TRANSPORT, AND ECO-EFFECTS

1. Reregistration Eligibility Decision (RED) for m-Cresol and Xylenol, EPA document: 738-R-94-025, 1994....

2. Memo: “ Ecological Effects Chapter for the 2,4-Xylenol (case 4098) and mCresol (case 4027) Reregistration Elig ibility Document. A Memo by Renee Lamb, Ecological Effects Branch of EFED to Tom Myers, Special Review and Reregistration Division, March 20, 1994

3. An Acceptance of Label: Letter to Ag BioChem, Inc. from Mary Waller, PM Fungicide Branch of Registration Division, September 17, 2009

4. EPI Suite, Version 4.10: An Estimati on (Screening level) Model Program, developed by OPPT.

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### APPENDIX A

DATA JUSTIFICATIONS

ENVIRONMENTAL FATE AND TRANSPORT

Guideline Number: 835.2120 Study Title: Hydrolysis Rationale for Requiring the Data Results from the hydrolysis study will indicate th e stability and persistence of 2,4-Xylenol, indicating the potential for this chemical to contaminate water discharged to WWTPs. In aquatic effluents, WWTPs may discharge directly to surface waters. The Agency will evaluate potential risks of concern. Practical Utility of the Data

1. How will the data be used? Data would show/help in establishing chemical hydrolysis as a route for degradation of a pesticide and to identify, if possible, the hydrolytic products formed which may adversely affect non-target organisms and

may contaminate water and food source of aquatic organisms. 2. How could the data impact th e Agency’s future decision-making? The results of hydrolysis data would indicate if 2,4-Xy lenol is persistent or it degrades into degradation products which may adversely affect non-target organi sms and may contaminate their food and water and possibly soil. 3. What is triggering the need for this data? Hydrolysis data is needed to conduct the fate assessment to support indoor uses for 2,4-Xylenol.



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### APPENDIX B

ECOLOGICAL EFFECTS DATA REQUIREMENTS

Guideline Number: 850.1075 Data Requirement: Acute Fish Toxicity (estuarine/marine) Rationale for Requiring the Data Sport fishing and commercial fishing have a high impact on the United States economy. The acute toxicity tests with estuarine/marine fish are desi gned to measure mortality during short-term (96-h) aquatic exposure to a range of concentrations of the pesticide in water. The preferred test species is

Atlantic silverside ( Menidia menidia ) for salt water. Practical Utility of the Data

1. How will the data be used? Data would be used to determine concentration-response curves and calculate LC50's (with 95% confidence intervals) for 24, 48, 72, and 96 h. Additionally, a NOEC for 96 h is reported. The

results from these studies may also provide information for a concentration-selection rationale for fish early-life stage study (OPPTS 850.1400) and the fish life cycle study (OPPTS 850.1500).

2. How could the data affect the risk assessment? There are many estuarine/marine fish species that are listed as threaten ed and endangered in the United States. Although the Atlantic silverside is the preferred species, the sheepshead minnow is considered a surrogate species to represent all mari ne/estuarine fish species in the risk assessment process. As part of the acute risk assessment for aquatic animals, the lowest EC50 or LC50 for

estuarine/marine fish is used in the RQ equation. An acute RQ > 0. 5 would indicate an acute LOC, defined as the potential for acute risk to non-target organisms which may warrant regulatory action in addition to restricted use classification. An acute RQ > 0.1 would result in an acute restricted use LOC, defined as the potential for acute risk to non-target organisms, which may be mitigated through restricted use classification. An acute RQ > 0.05 would fall under the LOC for acute endangered species.
3. What is triggering the need for this data? Data are needed in order to conduct an ecological risk assessment for the proposed use of 2,4- Xylenol as a wood preservative (bacteriocide) and determine the acute toxicity of m-Cresol to

estuarine/marine fish.



### 8Guideline Number: 850.2200 Data Requirement: Avian dietary toxicity test Rationale for Requiring the Data Birds eat certain insects and plants, wade in contaminated water, and ingest residue by preening. Over time, the residues build up to toxic levels . The value of this study is that it provides information on the oral toxicity of 2,4-xylenol to birds for a longer period (5 days of dietary exposure) compared to the acute di etary test with birds (single dose via oral gavage). The Northern bobwhite ( Colinus virginianus ) and mallard ( Anas platyrhynchos ) are the preferred test species. Practical Utility of the Data

1. How would the data be used? Mortality data would be used to determine con centration-response curves and calculate an LD50 (with 95% confidence interval) and NOEC. Clinical signs of toxicity, body weights, food consumption, and, possibly, gross pathology data would be used to characterize sublethal toxicity. Additionally, these data may be used to select dietary concentrations for use in the avian reproductive studies (OPPTS 850.2300).

2. How could the data affect the risk assessment? These bird species act as surrogate species for rept iles and terrestrial-phase amphibians, in addition to all other birds in the risk assessment process. There are many avian, reptile, and amphibian species that are listed as threatened and endangered in the United States. As part of the acute risk assessment for terrestrial animals, the lowest LD50 for avian toxicity is used in the RQ equation. An acute RQ > 0.2 would result in an acute restricted use LOC, defined as the potential for acute risk to non-target birds, which may be mitigated through restricted use classification.
3. What is triggering the need for this data? Data are needed in order to conduct an ecological risk assessment for the proposed use of 2,4- Xylenol as a wood preservative (bacteriocide) and determine the avian dietary toxicity of 2,4- Xylenol



### Guideline Number: 850.1010 Study Title: Acute Aquatic Invertebrate Rationale for Requiring the Data

This study will allow the Agency to determine the toxicity of 2,4-Xylenol to freshwater daphnids. An endangered species assessment for endangered or threaten ed freshwater daphnids is not possible without this study. Therefore, this study is required.

Practical Utility of the Data 1. How did the Agency make its re-reg istration decision without this data?

The Agency imposed risk mitigation through labeling changes as an interim measure.

2. How will the data be used?

The study will be used for hazard labeling in the event a spill of manufacturing use product occurs. This study will be used to generate a fre shwater invertebrate endpoint so that the Agency can evaluate the toxicity of m-Cresol to n on-target and endangered/threatened freshwater daphnids in freshwater aquatic ecosystems.



### 93. How could the data impact the Agency’s future decision-making?

If the acute freshwater fish toxicity is 1.0 mg/L or less, the label must state: “This pesticide is toxic to fish.” A freshwater fish endpoint will allow the Agency to determine if endangered or threatened species are at risk or if freshwater fish are impacted after residues pass through waste water treatment plants into surface waters. Mitigation might include reduced label dosages, neutralization of effluents prior to discharge into water, restrictions on use in sensitive ecosystems or where endangered species are presen t, or other mitigation measures which require

refined scientific assessments.



### Guideline Number: 850.2100 Study Title: Acute Aquatic Invertebrate

850.2100 Acute avian oral toxicity 1) What is the value of the study? The Agency currently does not have any acceptable acute avian oral toxicity data from 2,4-Xyle n the Agency to categorize 2,4-Xylenol as toxic or non-toxic to birds. If the avian acute oral LD 50 ( equal to 100 mg a.i./kg, additional hi gher tier bird test would be needed.

2) How would the data be used? This study would be used to evaluate the toxicity of 2,4-Xylenol to non-target birds in terrestrial a

3) How could the data affect the risk assessment? Adverse effects to non-target birds in terrestrial and aquatic ecosystems may result in mitigation t



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### APPENDIX C PRODUCT CHEMISTRY DATA REQUIREMENTS

Guideline Number: 830.1600 Study Title: Description of Materials used to Produce the Product
Guideline Number: 830.1620 Study Title: Description of Production Process
Guideline Number: 830.1650 Study Title: Description of Formulation Process
Guideline Number: 830.1670 Study Title: Discussion of Formation of Impurities
Guideline Number: 830.1700 Study Title: Preliminary Analysis
Guideline Number: 830.1750 Study Title: Certified Limits
Guideline Number: 830.1800 Study Title: Enforcement Analytical Method
Guideline Number: 830.6313 Study Title: Stability to sunlight, normal and elevated temperature
Guideline Number: 830.6314 Study Title: Oxidation/Reduction: Chemical Incompatibility
Guideline Number: 830.6315 Study Title: Flammability/Flash Point
Guideline Number: 830.6316 Study Title: Explodability
Guideline Number: 830.6317 Study Title: Storage Stability
Guideline Number: 830.6319 Study Title: Miscibility
Guideline Number: 830.6320 Study Title: Corrosion Characteristic
Guideline Number: 830.6321 Study Title: Dielectric Breakdown Voltage
Guideline Number: 830. 7000 Study Title: pH
Guideline Number: 830.7050 Study Title: UV/VIS absorption Spectra
Guideline Number: 830.7100 Study Title: Viscosity Rationale for Requiring the Data

Product chemistry requirements are necessary for regi stration of a pesticide. These data provide the complete characterization of a chemical. Practical Utility of the Data

1. What is the value of this study?

These data are needed to support the registration to allow EPA to evaluate the potential of the product

to cause unreasonable adverse effects on man and the environment. The data requirements are intended to generate the data and information necessary to address concerns pertaining to the identity,



### 11

### 12 composition, potential adverse effects and the enviro nmental fate of each product. Product chemistry data requirements are comprised of product identity and composition data along with the physical and chemical characteristics of a pesticide chemical.

2. How will the data be used?

This is basic information about the chemical which ensures chemical identity a nd is used to form the basis for labeling and product safety.

3. How could the data affect the risk assessment? Product chemistry data help in the characterization of the pesticide and some of these characteristics become important parameters in various sections or risk assessment (vapor pressure for exposure, Kow fo r bioaccumulation etc.)