Aniline (benzenamine): Environmental effects
Description
This substance may be hazardous to the environment; with special attention given to fish, crustaceans, and birds. Tests by the aniline industry show that aniline is highly toxic to aquatic life.
Aniline causes germination decrease, stunting, and size decreases (among other effects) on numerous agricultural crops.
Aniline acts to reduce the formation of photochemical smog.
Aniline is unlikely to exist in terrestrial environments in sufficient concentrations to cause serious acute or chronic effects to terrestrial organisms.
Entering the environment
Aniline in solution adsorbs strongly to colloidal organic matter, which effectively increases its solubility and movement into ground water. It is also moderately adsorbed to organic material in the soil. It will slowly volatilise from soil and surface water (vapour pressure 0.67 mm Hg @ 25°C) and is subject to biodegradation. Although rapidly degraded in the atmosphere, aniline can be deposited in the soil by wet and dry deposition, and by adsorption on aerosol particles.
Where it ends up
Air: Aniline degrades in the atmosphere primarily by reaction with photochemically produced hydroxyl radicals. The estimated half-life for aniline is 2 hours. The reaction products include nitrosamines, nitrobenzene, formic acid, nitrophenols, phenol, nitrosobenzene, and benzidine.
Soil: A number of microorganisms in soil can use aniline as a sole carbon and nitrogen source. Degradation of 44.2% of the incubated aniline to CO2 in 10 days and 12% in 20 days, respectively, by different isolated soil microorganisms has been demonstrated in the laboratory. Aniline bound to humic materials in the soil is subject to oxidation. Products apparently formed from oxidation include azobenzene, azoxybenzene, phenazine, formanilide, and acetanilide. Photodegradation of aniline on the soil surface is also thought to be an environmentally important removal process. The combination of these processes eventually results in the degradation of aniline to CO2. The half-life for the mineralisation of aniline to CO2 has been estimated at 4 days, utilising a model soil ecosystem. Information from studies done obtained under environmental conditions indicate that the half-life of aniline in the soil is less than one week
Water: Aniline in water is subject to biodegradation, photodegradation, and adsorption to sediment and humic materials. Low pH will increase the removal of aniline by adsorption; however, the adsorption to colloidal particles can extend the persistence of aniline in the aquatic environment. Although subject to oxidation when adsorbed to humic materials, aniline is resistant to hydrolysis. A half-life for aniline of 2.3 days has been reported in an industrial river. The presence of humic acids and various species of algae in the water can increase the photodegradation rates of aniline up to 50 fold.
Biota: The bioconcentration factor in two species of fish has been estimated at less than 1. A bioconcentration factor of 3 has also been calculated for fish. Aniline is not expected to accumulate significantly in aquatic organisms; however, it is absorbed and metabolised by fish.
Environmental guidelines
No national guidelines.
Key
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