UNITED STATES ENVIRONMENTAL 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 

1
TABLE OF CONTENTS 

2,4-XYLENOL: PRODUCT CHEMISTRY/ ENVIRONMENTAL FATE 

AND ECO-EFFECTS SCOPING DOCUMENT 

PAGE 

No. 

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

 2 

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

7 

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 very 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 actives: 2,4-xylenol and mcresol 

2
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 C8H10O 

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. 

3
Product Chemistry Summary

Table 3: Physical and Chemical 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 White1 

830.6303 Physical State Crystalline solid1 

830.6304 Odor Phenolic odor1 

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 26o C1 

830.7220 Boiling point 211o C at 760 mm Hg1 

830.7300 Density 0.97 g/cc at 20 o C1 

830.7370 Dissociation Constants in water 10.63 at 25 o C1 

830.7520 Particle size Not applicable 

830.7550 Octanol/water partition coefficient 

(KOW) (Log Kow ) 

2.351 

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

solutions1; 

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 C1 

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) 

4
Environmental Fate and Transport Data Summary:

EPA’s Reregistration Eligibility Decision (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. 

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 under 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 Eligibility 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 hydrolysis 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. 

5
BIBLIOGRAPHY FOR: PRODUCT CHEMISTRY, 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 Eligibility 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 AgBioChem, Inc. from Mary Waller, PM 

Fungicide Branch of Registration Division, September 17, 2009 

4. EPI Suite, Version 4.10: An Estimation (Screening level) Model Program, 

developed by OPPT. 

6
 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 the 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 the Agency’s future decision-making?

The results of hydrolysis data would indicate if 2,4-Xylenol is persistent or it degrades into degradation 

products which may adversely affect non-target organisms 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. 

7
 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 designed 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 threatened 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 marine/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.

8
Guideline 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 dietary 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 concentration-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 reptiles 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 threatened 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-registration 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 freshwater invertebrate endpoint so that the Agency 

can evaluate the toxicity of m-Cresol to non-target and endangered/threatened freshwater 

daphnids in freshwater aquatic ecosystems. 

9
 

 3. 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 present, 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-Xylen

the Agency to categorize 2,4-Xylenol as toxic or non-toxic to birds. If the avian acute oral LD50 

equal to 100 mg a.i./kg, additional higher 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

10
 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 registration 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 environmental 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 and 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 for bioaccumulation etc.)