Registration Dossier
Registration Dossier
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EC number: 210-323-0 | CAS number: 612-83-9
Endpoint summary
Administrative data
Description of key information
Additional information
Stability:
All available studies relating to stability had been performed with the base of the submission substance, 3,3´-dichlorobenzidine (DCB).
DCB is stable against hydrolysis at different pH-values. However, sunlight and, to a lesser extent UV-light, is capable of inducing fast phototransformation in air as well as in water (water: 70% transfromation in 10 minutes). In water, via the transient products monochlorobenzidine and benzidine, in water unsoluble coloured compounds are formed.
Biodegradation:
In the key study, 3,3´-dichlorobenzidine was tested for "ready biodegradablilty" in a sound and sufficiently well documented study (relibility score 2, reliable with restrictions) according to the OECD-guideline 301 A (AFNOR method) with deviations especially regarding substance concentration (much lower, because of the poor water solubility) and analytics (spectroscopic monitoring of substance concentration). The study results, constituted by the single results of serveral different laboratories taking part, demonstrate, that 3,3´-dichlororbenzidine is not readily biodegradable under the applied conditions (0% degradation at the end of the observation period). Experimental results pointing to inherent biodegradability in the presence of yeast extract as an external carbon source are rather to be seen as the result of the inherently strong adsoprtion potential of DCB to organic matter, which results in the withdrawal from the water phase.
Bioaccumulation:
Reported bioaccumulation factors (DCB) are especially high for activated sewage sludge (BAF = 3100, related to dry weight) and for green algae (BAF = 940, related to fresh weight). For fish, BAF between 500 and 600 have been reported.
Transport and distribution:
Adsorption/Desoprtion:
3,3´-dichlorobenzidine (DCB) is readily adsorbed by aquatic sediments. Depending on the carbon content, sediment-water partition coefficients between 20 to 128 have been determined. With prolonged contact time, a transition from physical adsorption to covalent bonds by condensation reactions of amino groups of DCB with carbonyl groups of the organic carbon content of the sediment might be the reason for the ever reduced desoprtion observed with time.
Henry´s law constant:
H (3,3´-dichlororbenzidine) = Ps/Cs = 5*10(-5) Pa * m3 * mol(-1) (at 20 -25 °C); therefore, volatility of DCB form aquatic solutions is expected to be low.
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