4-Hydroxybenzoic 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.

15 [mg/m3]

22 [mg/m3]

130 [mg/m3]

LC50 Oncorhynchus mykiss (Rainbow trout) >99 mg/L/96 hr /Conditions of bioassay not specified in source examined/

EC50 Daphnia magna (intoxication, immobilization) 181 mg/L/24 hr (95% confidence interval: 167-198 mg/L); 173 mg/L/48 hr; static

LD50 Oncorhynchus mykiss (Rainbow trout) ip 1.01 mmol/kg /formultated product/

TERRESTRIAL FATE: Based on a classification scheme(1), Koc values of 142, 20, and 14(2), indicate that 4-hydroxybenzoic acid is expected to have high to very high mobility in soil(SRC). Volatilization of 4-hydroxybenzoic acid from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 7.2X10-12 atm-cu m/mole(SRC), derived from its vapor pressure, 1.9X10-7 mm Hg(3), and water solubility, 5000 mg/L(4). In addition, the pKa of 4-hydroxybenzoic acid is 4.54(5), indicating that this compound will primarily exist in anion form in the environment and will not volatilize from moist soil surfaces(SRC). 4-Hydroxybenzoic acid is not expected to volatilize from dry soil surfaces(SRC) based upon its extrapolated vapor pressure value(3). Biodegradation of 4-hydroxybenzoic acid is expected to occur in aerobic and anaerobic soil environments based on both screening and microcosm studies (SRC). In aquifer sediment, from 34 to 70% mineralization was reported under aerobic conditions in 6 days(6). Under anaerobic conditions, 4-hydroxybenzoic acid was completely degraded in river sediments within 23 to 59 days(7).

AQUATIC FATE: Based on a classification scheme(1), Koc values of 142, 20, and 14(2)indicate that 4-hydroxybenzoic acid is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 7.2X10-12 atm-cu m/mole(SRC), derived from its vapor pressure, 1.9X10-7 mm Hg(4) and water solubility, 5000 mg/L(5). The pKa of 4-hydroxybenzoic acid is 4.54(9), indicating that this compound will primarily exist in anion form and anions generally do not adsorb more strongly to suspended solids and sediment than their neutral counterparts(6). According to a classification scheme(7), an estimated BCF of 9(SRC), from its log Kow(8) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is low (SRC). Biodegradation of 4-hydroxybenzoic acid is expected to occur in aerobic and anaerobic aquatic environments based on both screening and microcosm studies (SRC). In aquifer sediment, from 34 to 70% mineralization was reported under aerobic conditions in 6 days(10). Under anaerobic conditions, 4-hydroxybenzoic acid was completely degraded in river sediments within 23 to 59 days(11).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 4-hydroxybenzoic acid, which has an extrapolated vapor pressure of 1.9X10-7 mm Hg at 25 °C(2), is expected to exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase 4-hydroxybenzoic 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 30 hours(SRC), calculated from its rate constant of 1.3X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase 4-hydroxybenzoic acid may be removed from the air by wet and dry deposition(SRC).

The CIR Expert Panel concluded that the following 20 parabens are safe in cosmetics in the present practices of use and concentration described in the safety assessment when the sum of the combined concentration of parabens in any given formulation does not exceed 0.8 %...4-Hydroxybenzoic Acid...

Safe for use in cosmetics, with qualifications

Night soil treatment plant effluents collected on two occasions in Japan in 1975 contained 4-hydroxybenzoic acid at 2.0 and 2.5 ug/L(1). Incinerating plant effluent collected in Japan in 1975 contained 4-hydroxybenzoic acid at a concentration of 6.5 ug/L(1).

Koc values of 142, 20, and 14 were measured according to a modified version of OECD guideline 106 for 4-hydroxybenzoic acid in a podzol (pH=2.8, C organic=4.85%, sand:silt:clay=89.2:8.2:2.6%), alfisol (pH=6.7, C organic=1.25%, sand:silt:clay=69.7:14.4:15.9%), and a sediment (pH=7.1, C organic=1.58%, sand:silt:clay=5.5:58.8:35.7%), respectively(1). According to a classification scheme(2), these Koc values suggest that 4-hydroxybenzoic acid is expected to have high to very high mobility in soil. The pKa of 4-hydroxybenzoic acid is 4.54(3), indicating that this compound will primarily exist in anion form in the environment and anions generally do not adsorb more strongly to organic carbon and clay than their neutral counterparts(4).

URBAN/SUBURBAN: Aerosol samples collected in April 1985 approximately 60 km northeast of Tokyo in a suburban area surrounded by agricultural fields and forests contained unreported concentrations of 4-hydroxybenzoic acid(1). 24-Hour air samples collected from two urban sites in the San Joaquin valley, CA from December 5, 1995 to January 6, 1996 contained 4-hydroxybenzoic acid at 7.8(Bakersfield, CA) and 12 (Fresno, CA) ng/cu m(2). Atmospheric fallout samples collected in a residential district of Tokyo, Japan, between February 1976 and January 1978, contained 4-hydroxybenzoic acid at concentrations ranging from 0.3 to 4.7 ug/cu m/day(3).

RURAL/REMOTE: 24-Hour air samples collected from the Kern Wildlife refuge in the San Joaquin valley, CA, from December 5, 1995 to January 6, 1996 contained 4-hydroxybenzoic acid at 0.6 ng/cu m(1).

AEROBIC: In a 1% soil suspension screening test, 4-hydroxybenzoic acid at 25 ppm was completely degraded within 1 day, as measured by loss of UV absorbancy(1). 4-Hydroxybenzoic acid was readily biodegraded in several aerobic activated sludge screening tests including the Zahn-Wellens test (100% removal in 1 day), Japanese MITI test (98% theoretical BOD reached in 14 days), Sturm CO2 evolution test (61% theoretical CO2 produced in 28 days), OECD Screening test (95% DOC removal in 19 days), and the Closed bottle test (93% theoretical BOD reached in 30 days)(2). In an OECD coupled units biological treatment simulation test, 99% DOC removal of 4-hydroxybenzoic acid, initially present at 12 ppm C, was reported after an acclimation period of 7 days(2). 4-Hydroxybenzoic acid was mineralized 44 to 54% in 14 days in an assay where aquifer sediments from outside the coal-tar contaminated plume were added to the compound in distilled water at 20 °C(3). When aquifer sediment collected from within the plume were used, from 50 to over 80% of the added 4-hydroxybenzoic acid was generally mineralized within 14 days(3). Under microaerophilic conditions, mineralization of 4-hydroxybenzoic acid ranged from 13 to 54% in 6 days; sediment collected from within the plume was used as an inoculum(3). Under aerobic conditions, using the same sediment, from 34 to 70% mineralization was reported over the same time(3). The percent 4-hydroxybenzoic acid mineralization in 20 days ranged from 35 to 55, 35 to 55, and 0 to 35 in microcosms using sediment upgradient of a coal-tar contaminated plume, downgradient of the plume, and in pristine sediment, respectively(4). Mineralization of 4-hydroxybenzoic acid in aquifer sediment microcosms from uncontaminated and contaminated boreholes in an urban coal-tar waste site was reported as 43 to 51% and 46 to 52%, respectively, in 14 days(5).

ANAEROBIC: 4-Hydroxybenzoic acid was slowly mineralized in a microcosm study using aquifer sediment and groundwater from two boreholes in a coal-tar contaminated aquifer; the percent mineralization ranged from 0 to 30% in 28 days(1). 4-Hydroxybenzoic acid was readily degraded in several anaerobic digester sludge screening studies. Digester sludge from the Adrian and Jackson waste treatment plants, present at 10% in an anaerobic salts medium, degraded 100% of the added 4-hydroxybenzoic acid (at 50 ppm C) within 14 days(2). Complete mineralization of 4-hydroxybenzoic acid was reported within 14 days in a screening study using anaerobic digester sludge (initial test compound concentration of 30 mg C/L, sludge inoculum at 100 mg C/L, incubation at 37 °C, glucose and glutamic acid added)(4). In a second similar digester sludge screening test, 87% mineralization was reported in 28 days(5). In another digester sludge screening study, 17 days were required to completely degrade 4-hydroxybenzoic acid with over 80% of the initial concentration converted to gas(6). Significant mineralization of 4-hydroxybenzoic acid in a freshwater lake sediment was noted in 2 to 4 weeks(2). In anaerobic sediment slurries constructed using sediment from the Milwaukee Harbor and Green Bay, complete degradation of 4-hydroxybenzoic acid was generally reported in 24 to 59 days and 23 to 51 days, respectively(3). 4-Hydroxybenzoic acid was mineralized by 96 and 121% under denitrifying and methanogenic conditions, respectively, in a screening study using a 10% sediment slurry inoculum(7). Mineralization rate constants of >70(lag phase of 0 to 1.4 weeks) and 20 umol/L/day(lag phase of 0 to 1 week) were reported for 4-hydroxybenzoic acid during its degradation under denitrifying and methanogenic conditions, respectively(7).

SOIL: A peat soil contained 4-hydroxybenzoic acid at a concentration of 265 to 727 ug/100 gm dry soil(1). 4-Hydroxybenzoic acid dominated the other phenolic carboxylic acids present in soil samples collected from the McMurdo Sound region of the Antarctic(2). A composite of soil samples collected in a residential district of Tokyo, Japan, between February 1976 and January 1978, contained 4-hydroxybenzoic acid at a concentration of 4.2 ug/g dry soil(3). 4-Hydroxybenzoic acid concentrations in 5 freshwater sediment samples ranged from 3.47 to 133 ug/g dry weight(4).

SEDIMENT: 4-Hydroxybenzoic acid dominated the other phenolic carboxylic acids present in sediment samples collected from the McMurdo Sound region of the Antarctic(1). Sediments collected from Lake Haruna, Tama river, Komagari reservoir, Yatsuse river, and the Gulf of Mexico contained 4-hydroxybenzoic acid at 14, 1.2, 7.9, 16, and 0.51 ug/g dry sediment(2).

An estimated BCF of 9 was calculated for 4-hydroxybenzoic acid(SRC), using a log Kow of 1.58(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), provided the compound is not altered physically or chemically once released into the environment.

This action promulgates standards of performance for equipment leaks of Volatile Organic Compounds (VOC) in the Synthetic Organic Chemical Manufacturing Industry (SOCMI). The intended effect of these standards is to require all newly constructed, modified, and reconstructed SOCMI process units to use the best demonstrated system of continuous emission reduction for equipment leaks of VOC, considering costs, non air quality health and environmental impact and energy requirements. 4-Hydroxybenzoic acid is produced, as an intermediate or a final product, by process units covered under this subpart.