Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information


With regard to the chemical structure, o-toluidine is not expected to hydrolyse due to the lack of hydrolysable functional groups.

Phototransformation in air:

In the atmosphere, the substance is degraded by photochemically produced OH radicals. The estimated half-life was 2.915 hours, therefore the substance has no potential for long-range transport.


The biodegradability of o-toluidine was tested by 6 different laboratories under the conditions described by the OECD TG 301 A and E. Based on DOC measurement the following results were obtained after 28 days: with the method OECD TG 301 E, five laboratories obtained > 90 % biodegradation, the other one reported a 67 % value. The results obtained with the method OECD TG 301 A showed biodegradation between 88 and 90 % after 28 days.

Additionally according to the national Japanese standard method comparable to the OECD TG 301 C guideline an aerobic ready test was performed. After a period of 28 days 65.4 % biodegradation was observed.

Results on the inherent biodegradability of o-toluidine are also available.

The chosen test design was comparable to the Zahn-Wellens-Test (OECD TG 302 B). Based on COD measurement, a removal of 97.7 % within 5 days was obtained.

With adapted activated sludge from an industrial sewage treatment plant a test on inherent biodegradation was conducted. After 11 days (4 days adaptation) 96 % of the initial concentration were removed.

Under anaerobic conditions o-toluidine could not be removed after a period of 10 months in an aquifer slurry. o-Toluidine revealed no biotic transformation, neither under sulfate reducing nor under methanogenic conditions.

In a further test o-toluidine could not be removed after 150 days in a landfill environment under anaerobic conditions. The test was not performed according to current standard methods but indicates that the substance is stable under anaerobic terms.


As no data on BCF were available for o-toluidine the structural analogue p-toluidine was considered to assess the potential for bioaccumulation of the substance.

An experimentally determined BCF value for the structural analogue of < 13 indicates a very low bioaccumulation potential.

An experimentally determined logKow of 1.4 for o-toluidine supports this consideration that the substance has a low potential for bioaccumulation. Therefore a potential for secondary poisoning is not expected.

In addition experimental bioconcentration factors (BCF) for o-toluidine indicate no significant potential for bioaccumulation in oysters (Crassostrea gigas) or mussels (Mytilus edulis). The obtained BCF values were 4.2 and 4.6 for mussels and oyster, respectively.

Adsorption /desorption:

The Koc for o-toluidine was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v 4.11. The Koc was estimated to be 47.63 L/kg (logKow method), and 115 L/kg (MCI method).

The coefficient of distribution (Kd) between the sediment extracted from an aquifer was measured. A Kd of 0.013 was observed for o-toluidine, the Koc was calculated to be 87.

These results indicate a low sorption potential of o-toluidine onto the organic phase of soil or sediments according to the criteria of Litz (1990).

However, adsorption of o-toluidine in soil is influenced by ion-ion interactions. The mechanism responsible for adsorption of o-toluidine and other amines was investigated on montmorillonite. The maximum adsorption occurs when the pH is approximately equal to the pKa (4.44 - 4.45) of the protonation reaction.


Indicated by a Henry's Law constant of 0.2 Pa m³/mol o-toluidine is slightly volatile from water.