Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Biodegradation

The substance is not readily and not inherently biodegradable.

Hydrolysis

MDI reacts with water to form predominantly inert polyurea. Yakabe et al (1994) found that for loadings of 400 - 10,000 mg/l, and under heterogeneous conditions, MDI had a half-life of ca. 20h at 25°C when the disappearance rate was fitted to a zero-order kinetic model. Howver the rate constant increased approximately linearly with the nominal concentration of PMDI for all constituents. For the two-ring constituents the rate constant was found to be 0.5h-1 for a loading of 1000 mg/L PMDI.

Neither Desmodur PF nor polymeric MDI are biodegradable.

Phototransformation in Air

The half-life in the atmosphere has been estimated using the AOPWIN (TM) (v1.92) model and was 0.92 days.

Hydrolysis

MDI reacts with water to form predominantly inert polyurea. Yakabe et al (1994) found that for loadings of 400 - 10,000 mg/l, and under heterogeneous conditions, MDI had a half-life of ca. 20h at 25°C when the disappearance rate was fitted to a zero-order kinetic model. Howver the rate constant increased approximately linearly with the nominal concentration of PMDI for all constituents. For the two-ring constituents the rate constant was found to be 0.5h-1 for a loading of 1000 mg/L PMDI.

Bioaccumulation

MDI is virtually unavailable in aqueous solution, and in consequence no bioaccumulation of the substance is expected. The bioconcentration of 4,4’-MDI has been evaluated in this study, using flow-through exposures of 0.8 and 0.08 ug/L MDI. Whereas the analytics (liquid scintillation counting) for this study are suspect due to the expected reactivity of MDI in water and fish tissues, steady state bioconcentration factors (BCFss) of 92 and 200 are reported for these respective MDI exposure concentrations. Using a similar test procedure with (Cyprinius carpio), no measureable bioconcentration of the 4,4'-MDA substance, present at only low concentrations from reaction of MDI with water, was observed. Based on the exposure concentration (0.2 and 0.02 mg/L) and analytical detection limits for water and fish tissues, BCF values of 3-14 and <3-15 (respectively) were reported for these MDA exposures. (EU Risk Assessment Report 4,4’-methylenedianiline).