Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

AIR COMPARTMENT

2,4-Dinitrophenol can be release to the environment through various waste streams, due to the production and use in the manufacture of dyes.

The vapour pressure of 2,4-dinitrophenol is 1.49X10^-5 mm Hg at 18 °C. Organics with vapour pressures of 10^-4to 10^-4mm Hg at ambient temperature should exist partly in the vapour and partly in the particulate phase in the atmosphere (Eisenreich et al. 1981). Hence, the value of vapour pressure indicates that the 2,4-dinitrophenol will exist as a vapour in the ambient atmosphere and partly present in the particulate phase in the air.

In the gas phase, photodegradation may be an important fate process although the kinetics of this reaction are unknown (Atkinson et al., 1992). 2,4-dinitrophenol may be susceptible to direct photolysis by sunlight (> 290 nm)(Sadtler Res lab).

Once in the atmosphere, 2,4-dinitrophenol will be degraded in by reaction with photochemically-produced hydroxyl radicals, the half-life for this reaction in air is estimated to be 28 days degradation rate constant with OH radicals 5.76x10^-13cm3 . Conversely, reaction with nitrate radicals should not be a significant environmental fate (by structural analogy) (Grosjean D. 1985).

Nevertheless since dinitrophenols are expected to be present partly in the particulate phase in the air, the reaction rate is expected to be even slower than the estimated value for the gas phase reaction (Atkinson R. et al., 1988), so significant removal of dinitrophenols from the atmosphere due to photochemical or other chemical reactions is not likely.

WATER COMPARTMENT

Phototransformation in water still would not be important in water (half-life of ≈500 days).This value is based on the reaction between 2,4-dinitrophenol, singlet oxygen (O2) and peroxy radicals (RO2) concentrations.

The half-life of ~ 500 days was determined from the experimental value of the rate constant of 2,4-DNP’s reaction with singlet oxygen concentration 4.05x10^5 molar-second and the estimated average of the singlet oxygen concentration in typical eutrophic fresh water was 4x10^-14 molar (Tratnyek et al. 1991).

Similar values were calculated by Mabey WR, et al. 1981 concluding that the estimated rates of the reaction were 3x10^4 molar-hour for singlet oxygen (O2) and 5x10^5/molar hour for peroxy radicals (RO2).

Usually, concentration of singlet oxygen and peroxy radicals in typical eutrophic waters are 10^-12 and 10^-9 molar, respectively. Hence, the reaction of hydroperoxy radicals (HO2) with 2,4-DNP producing a ring hydroxylated products would not be significant (by classical Fenton reaction)(Mill and Mabey 1985).

Furthermore the direct photolysis of 2,4-DNP in water is too slow to be an important environmental fate process (Lipczynska-Kochany E, 1991).

2,4-DNP may be also photoreduced to 2-amino-4-nitrophenol in the presence of ascorbic acid or ferrous ions, and the reaction is sensitized by chlorophyll. The possibility of such photoreduction exists in natural water in which the suspended reducing matter may act as a reducing agent and humic substances or algae may serve as a sensitizer (Massini P, Voorn G. 1967).

SOIL COMPARTMENT

No study was located that reported the abiotic degradation/transformation of dinitrophenols in soil.

It has been speculated that 2,4-DNP in soil may be reduced to 2-amino-4-nitrophenol by sunlight in the presence of a reductant, such as ferrous ions and a sensitizer, such as chlorophyll (Kaufman 1976; Overcash et al. 1982; Shea et al. 1983). Despite these considerations, the sunlight would not penetrate below the surface layer of soil.