Acetic Acid

CAS RN: 64-19-7

Exposure Summary

Acetic acid's production and use in the in the manufacture of various acetates and other chemicals, food preservation, textile dyeing, and as a pharmaceutical aid may result in its release to the environment through various waste streams. Its use in hydrofracking operations will result in its direct release to the environment. Atmospheric emissions occur from combustion of biomass, plastics and refuse and in exhaust from gasoline and diesel engines. Acetic acid is a natural product of fermentation and widely used in the form of common vinegar. Acetic acid occurs in ocean water, oilfield brines, rain, and at trace concentrations in many plant and animal liquids. Formation of acetic acid can occur via the reaction of olefins with ozone in the atmosphere. Decomposition of solid biological wastes produces acetic acid which is readily metabolized by living organisms; acetic acid occurs as a normal metabolite in both plants and animals. If released to air, a vapor pressure of 15.7 mm Hg at 25 deg C indicates acetic acid will exist solely as a vapor in the ambient atmosphere. The pure compound is a solid below 68 deg F. Vapor-phase acetic 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 22 days. Particulate-phase acetic acid will be removed from the atmosphere by wet and dry deposition. Acetic acid does not absorb light with wavelengths >290 nm, and is not expected to be susceptible to direct photolysis by sunlight. Acetic acid occurs in rainwater, cloud water and fog and can be removed from the atmosphere by wet deposition. If released to soil, acetic acid is expected to have very high mobility based upon a Koc value of 1.0. The pKa of acetic acid is 4.76, indicating that this compound will exist partially in anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts. Volatilization from moist soil surfaces is not expected to be an important fate process based upon a Henry's Law constant of 1.43X10-7 atm-cu m/mole. Acetic acid is expected to volatilize from dry soil surfaces based upon its vapor pressure. Using a modified Organization of Economic Cooperation and Development (OECD) protocol, 75% degradation was reported in 14 days using garden soil as an inoculum, indicating that biodegradation is an important environmental fate process in soil. A variety of biological screening studies have determined that acetic acid biodegrades readily under anaerobic conditions. If released into water, acetic acid is not expected to adsorb to suspended solids and sediment based upon the Koc value. Utilizing the Japanese MIT test, a 74% of theoretical BOD in 2 weeks using activated sludge indicates that biodegradation is an important environmental fate process in water. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's Henry's Law constant. 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. Occupational exposure to acetic acid may occur through inhalation and dermal contact with this compound at workplaces where acetic acid is produced or used. Acetic acid occurs ubiquitously and is a normal metabolite in animals; therefore, the general population is continually exposed to the compound. Monitoring data indicate that the general population may be exposed to acetic acid via inhalation of ambient air, ingestion of food, and dermal contact with consumer products containing acetic acid. (SRC)
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