Benzidine-2,2'-disulphonic acid

Endpoint summary

Additional information

Phototransformation in air

The atmospheric oxidation half-life ofBenzidine-2,2-disulphonic acidwas estimated using the level III multimedia model. It was estimated that the substance was not persistent in air medium as the half life period ofBenzidine-2,2’-disulphonic acidin air is 0.5 days. This indicates thatBenzidine-2,2-disulphonic acidis easily phototransformed in air.

Medium	Half life in Days	Percent in medium
Air	0.5	0%

Hydrolysis

Hydrolysis half life of Benzidine-2,2’-disulphonic acid is estimated to be 3.870 h while the hydrolysis rate constant is estimated to be 33.1629 E-12 cm3/molecule-sec. The estimated half life of the substance indicates that the substance is moderately hydrolysable.

Bio-degradation

Biodegradation in water:

The substance Benzidine-2,2’-disulphonic acid is 50% biodegradable in water in 38 days (half-life). This value indicates that Benzidine-2,2’-disulphonic acid is readily biodegradable in water since the half life is less than the threshold of <= 60 days (to qualify the chemical as not persistent).

Medium	Half life in Days	Percent in medium
Water	38	12%

Biodegradation in Water / Sediment :

Based on the Level III Fugacity Model , the half life period of the Benzidine-2,2’-disulphonic acid was estimated.

Half life period of Benzidine-2,2’-disulphonic acid in water was observed to be 38 days while in sediment it is 340 days. Based on these half life values of it is concluded that Benzidine-2,2’-disulphonic acid is readily biodegradable in water where as it is non biodegradable in sediment. However, since there is no diffusion of the substance in the sediment as evident from the reported data (0 % in sediment) and hence persistence in the sediment compartment is not likely to be critical.

The Supporting study also indicates that half life period of Benzidine-2,2’-disulphonic acid in water and sediment as900 hrs (37.5 days) and8100 hrs (337.5days) respectively.

Medium	Half life in Days	Percent in medium
Water	38	12%
Sediment	340	0%

Media	Half life (hrs)	Percent in medium	Emission (kg/hr)
Water	900	12.3%	1000

Biodegradation in soil:

Based on the Level III Fugacity Model , the half life period of the Benzidine-2,2’-disulphonic acid was estimated.

Half life period of Benzidine-2,2’-disulphonic acid in soil was observed to be 75 days. Based on these half life values it is concluded that Benzidine-2,2’-disulphonic acid is not readily biodegradable (persistent) in soil since the half life period of Benzidine-2,2’-disulphonic acid exceeds the threshold of 60 days (to qualify the chemical as persistent)

The supporting study also indicates that the half life of Benzidine-2,2’-disulphonic acid to be 1800 hrs (75 days).

Medium	Half life in Days	Percent in medium
Soil	75	87%

Media	Half life (hrs)	Percent in medium	Emission (kg/hr)
Soil	1800	87.3%	1000

Bio-accumulation

Bioaccumulation :

Bioaccumulation in Aquatic / Sediment :

Bioaccumulation is the process by which the chemical concentration in an aquatic organism achieves a level that exceeds that in water as a result of chemical uptake through all possible routes of exposure. The relationship between Bioaccumulation and Bioconcentration is that, chemicals that have potential to bioconcentrate also have potential to bioaccumulate. Bioaccumulation is closely related to bioconcentration factor (BCF)

The estimated bioconcentration factor (BCF) for Benzidine-2,2’-disulphonic acid is 1.129889.which does not exceed the bioconcentration threshold of 1000.

Other Weight of evidence studies also indicates that the bioconcentration factor to be 3.2 and 3.162 which does not exceed the bioconcentration threshold of 1000.

Sr no	Endpoint name	Value	Species
1	BCF	1.129889	Cyprinus carpio
2	BCF	3.2	Fish
3	BCF	3.162	Fish

From this it is concluded that Benzidine-2,2’-disulphonic acid is not expected to bioaccumulate in the food chain.

Transport and distribution

Adsorption/desorption:

Soil Adsorption Coefficient i.e. Koc value of Benzidine-2,2’-disulphonic acid at 25 deg C was estimated as 584.5 L/kg {Log Koc (2.7668) } by means of MCI method. This indicates that Benzidine-2,2’-disulphonic acid has good adsorption potential to the organic carbon fraction of the soil and shall have slow migration potential to groundwater.Log Koc value at 20 deg C is equivalent to 2.669

Henry's Law constant:

Henry's Law states that at a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.

Henrys Law Constant of Benzidine-2,2’-disulphonic acid at 25 deg C was estimated to be 1.14E-018 Pa m³/mol