Indole-3-Butyric Acid

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

An exemption from the requirement of a tolerance is established for residues of auxins (specifically: indole-3-acetic acid and indole-3-butyric acid) in or on all food commodities when used as plant regulators on plants, seeds, or cuttings and on all food commodities after harvest in accordance with good agricultural practices.

LC50 Oncorhynchus mykiss (Rainbow trout,donaldson trout) >90.5 ppm/96 hr; static /formulated product/

EC50 Daphnia magna (Water flea; intoxication, immobilization) 57 ppm/48 hr (95% confidence interval: 46-74 ppm); static /formulated product/

LC50 Colinus virginianus (Northern bobwhite, 14 day old) diet >5,000 ppm (in the diet)/8 days

LC50 Colinus virginianus (Northern bobwhite, 20 wk old) oral >2,150 mg/kg/14 days

EC50 Lactuca sativa (Lettuce; inhibition of germination) 0.06 mol/cu m/72 hr

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 550(SRC), determined from a structure estimation method(2), indicates that indolebutyric acid is expected to have moderate to low mobility in soil(SRC). The estimated pKa of indolebutyric acid is 4.7 for the ionization of the carboxylic acid group(3), indicating that this compound will primarily exist in the dissociated form in the environment; anions generally do not adsorb to organic carbon and clay as strongly as their neutral counterparts(4). Volatilization of indolebutyric acid from moist soil surfaces is not expected to be an important fate process, since indolebutyric acid is expected to exist primarily in its dissociated form in the environment(SRC). Volatilization of the undissociated form of indolebutyric acid from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.3X10-11 atm-cu m/mole(SRC), developed using a fragment constant estimation method(7). Indolebutyric acid is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 1.8X10-6 mm Hg(SRC), determined from a fragment constant method(5). Indolebutyric acid was reported to degrade rapidly in soil(6).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 550(SRC), determined from a structure estimation method(2), indicates that indolebutyric acid is not expected to adsorb to suspended solids and sediment(SRC). This compound is expected to exist in the dissociated form in the environment, based on an estimated pKa of 4.7 for the ionization of the carboxylic acid group(3), and therefore volatilization from water surfaces is not expected to be an important fate process(SRC). Volatilization from water surfaces is not expected for the undissociated form of indolebutyric acid(9) based upon an estimated Henry's Law constant of 1.3X10-11 atm-cu m/mole(SRC), developed using a fragment constant estimation method(10). Indolebutyric acid is not expected to undergo hydrolysis in the environment due to the lack of hydrolyzable functional groups(4). Indolebutyric acid was reported to be very stable in neutral, acidic, or alkaline media(5). According to a classification scheme(6), an estimated BCF of 3(SRC), from its log Kow of 2.30(7) and a regression-derived equation(8), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data for indolebutyric acid in water were not found; however, indolebutyric acid was reported to degrade rapidly in soil(11).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), indolebutyric acid, which has an estimated vapor pressure of 1.8X10-6 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase indolebutyric acid is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 2 hours(SRC), calculated from its rate constant of 2.0X10-10 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase indolebutyric acid may be removed from the air by wet and dry deposition(SRC). Indolebutyric acid may be susceptible to direct photolysis by sunlight(SRC), since it has an absorbance at 290 nm(4).

Using a structure estimation method based on molecular connectivity indices(1), the Koc for indolebutyric acid can be estimated to be 550(SRC). According to a classification scheme(2), this estimated Koc value suggests that indolebutyric acid is expected to have low mobility in soil. The estimated pKa of indolebutyric acid is 4.7 for the carboxylic acid group(3), indicating that this compound will primarily exist in the dissociated form in the environment; anions generally do not adsorb to organic carbon and clay as strongly as their neutral counterparts(4).

Indolebutyric acid's production may result in its release to the environment through various waste streams; its use as a rooting hormone for plant cuttings and plant growth regulator(1,2) will result in its direct release to the environment(SRC).

An estimated BCF of 3 was calculated for indolebutyric acid(SRC), using a log Kow of 2.30(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

This compound is expected to exist in the dissociated form in the environment, based on an estimated pKa of 4.7(1), and therefore volatilization from water surfaces or moist soil surfaces is not expected to be an important fate process(SRC). Indolebutyric acid is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 1.8X10-6 mm Hg(SRC), determined from a fragment constant method(2).

/LABORATORY ANIMALS: Acute Exposure/ ...These products have low acute toxicity as suggested from data of at least one formulated product (Toxicity Categories III and IV), no dermal irritation , and moderate eye irritation, perhaps from another active or an inert ingredient in the product formulation. /Formulated Indole-3-butyric acid/

/GENOTOXICITY/ ...Indole-3-butyric acid (IBA), was tested for genetic activity in Aspergillus nidulans in a plate test. IBA was found to greatly increase somatic segregation in the fungus. ... It was found that increasing concentrations of IBA increased mitotic segregation of the fungus with most of the segregants being produced by mitotic crossing-over, together with non-disjunctional segregants at a lower level. The metabolic activation technique was also used and it was shown that when S9 mixture was added to IBA a further 3- to 5-fold increase in the number of segregants was obtained.

/GENOTOXICITY/ The plant growth-regulating hormones indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), both strong recombinogens in Aspergillus nidulans, were tested in Salmonella typhimurium strains for his revertants at a range of concentrations from 1 to 2000 micrograms/plate with and without metabolic activation and were found negative.

The rate constant for the vapor-phase reaction of indolebutyric acid with photochemically-produced hydroxyl radicals has been estimated as 2.0X10-10 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 2 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Indolebutyric acid is not expected to undergo hydrolysis in the environment due to the lack of hydrolyzable functional groups(2). Indolebutyric acid was reported to be very stable in neutral, acidic, or alkaline media(3). Indolebutyric acid may be susceptible to direct photolysis by sunlight(SRC), since it has an absorbance at 290 nm(4).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 864 workers are potentially exposed to indolebutyric acid in the US(1). Occupational exposure to indolebutyric acid may occur through inhalation and dermal contact with this compound at workplaces where indolebutyric acid is produced or used(SRC). The general population may be exposed to indolebutyric acid via dermal contact with consumer products containing indolebutyric acid(SRC).

Indolebutyric acid's production may result in its release to the environment through various waste streams; its use as a rooting hormone for plant cuttings and plant growth regulator will result in its direct release to the environment. If released to air, an estimated vapor pressure of 1.8X10-6 mm Hg at 25 °C indicates indolebutyric acid will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase indolebutyric acid will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 2 hours. Particulate-phase indolebutyric acid will be removed from the atmosphere by wet and dry deposition. Indolebutyric acid may be susceptible to direct photolysis by sunlight, since it has an absorbance at 290 nm. If released to soil, indolebutyric acid is expected to have moderate to low mobility based upon an estimated Koc of 550. The estimated pKa of indolebutyric acid is 4.7 for the ionization of the carboxylic acid group, indicating that this compound will primarily exist in the dissociated form in the environment and anions generally do not adsorb to organic carbon and clay as strongly as their neutral counterparts. Volatilization from moist soil surfaces is not expected to be an important fate process for indolebutyric acid, since it is expected to exist primarily in its dissociated form in the environment. Volatilization from moist soil surfaces is not expected for the undissociated form of indolebutyric acid based on an estimated Henry's Law constant of 1.3X10-11 atm cu m/mol. Volatilization from dry soil is not expected based upon indolebutyric acid's estimated vapor pressure. Indolebutyric acid was reported to degrade rapidly in soil. If released into water, indolebutyric acid is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. This compound is expected to exist in the dissociated form in the environment and therefore volatilization from water surfaces is not expected to be an important fate process. An estimated BCF of 3 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions. Indolebutyric acid was reported to be very stable in neutral, acidic, or alkaline media. Occupational exposure to indolebutyric acid may occur through inhalation and dermal contact with this compound at workplaces where indolebutyric acid is produced or used. The general population may be exposed to indolebutyric acid via dermal contact with consumer products containing indolebutyric acid. (SRC)

/SRP:/ Basic treatment: Establish a patent airway. Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with normal saline during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poison A and B/

/SRP:/ Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in respiratory arrest. Positive pressure ventilation techniques with a bag valve mask device may be beneficial. Monitor cardiac rhythm and treat arrhythmias as necessary ... . Start an IV with D5W /SRP: "To keep open", minimal flow rate/. Use lactated Ringer's if signs of hypovolemia are present. Watch for signs of fluid overload. Consider drug therapy for pulmonary edema ... . For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam (Valium) ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poison A and B/

An exemption from the requirement of a tolerance is established for residues of auxins (specifically: indole-3-acetic acid and indole-3-butyric acid) in or on all food commodities when used as plant regulators on plants, seeds, or cuttings and on all food commodities after harvest in accordance with good agricultural practices.

As the federal pesticide law FIFRA directs, EPA is conducting a comprehensive review of older pesticides to consider their health and environmental effects and make decisions about their future use. Under this pesticide reregistration program, EPA examines health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether they are eligible for reregistration. In addition, all pesticides must meet the new safety standard of the Food Quality Protection Act of 1996. Pesticides for which EPA had not issued Registration Standards prior to the effective date of FIFRA '88 were divided into three lists based upon their potential for human exposure and other factors, with List B containing pesticides of greater concern and List D pesticides of less concern. Indole-3-butyric acid is on List B. Case No: 2330; Pesticide type: fungicide, herbicide; Case Status: RED Approved 09/1992; OPP has made a decision that some/all uses of the pesticide are eligible for reregistration, as reflected in a Reregistration Eligibility Decision (RED) document.; Active ingredient (AI): indole-3-butyric acid; AI Status: OPP has completed a Reregistration Eligibility Decision (RED) for the case/AI..

The Agency ... finds that products containing only IBA as an active ingredient are eligible for reregistration once the product specific data, confirmatory ecotoxicity data, and amended labeling are received and accepted by the Agency. Products that contain additional active ingredients will be reregistered once the Agency completes eligibility decisions on the other active ingredients and once product specific and amended labeling are received and accepted.