Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

p-TSH is not readily biodegradable according to OECD Guideline no. 301C.

The hydrolytic half life of p-TSH at 20 °C was:

138.63 h at pH 4

38.51 h at pH 7

40.77 h at pH 9

These data suggest that p-TSH will degrade hydrolytically at environmentally relevant pH and temperature conditions. The primary degradation products are hydrazine and p-Toluenesulfonic acid.

Once released into the water environment, p-TSH will readily - due to hydrolysis - be degraded into primarily hydrazine and p-Toluenesulfonic acid

Some retention of the waste water within in the industrial settings can be expected. The travelling time from p-TSH is released into waste water until arrival in the STP can vary quite much - in dependence of the distance to plant and the flow velocity. Typically, the flow velocity in the sewer is about 1 m/s, and with an average distance between the point of discharge and STP of 10 km, a retention time in the sewer of approximately 3 hours is calculated. In the sewer, a pH above 7 is usual (in order to limit the concentration of free H2S and to limit the corrosion due to the presence of sulfuric acid).

The overall retention time in a standard SimpleTreat sewage treatment plant (STP) is approximately 15 hours. Overall, a total retention time of 1 day = 24 hours is assessed to be a reasonable value to apply for the risk assessment. A pH between 7 - 8 is expected in the sewer and the sewage treatment plant.

In conclusion, a total hydrolytic transformation of approximately 65% before final discharge into the environment is assessed to be a reasonable value to use for the environmental risk assessment.

Additional information

p-TSH is not readily biodegradable according to OECD Guideline no. 301C.

The hydrolytic half life of p-TSH at 20 degrees celcius was:

138.63 h at pH 4

38.51 h at pH 7

40.77 h at pH 9

These data suggest that p-TSH will degrade hydrolytically at environmentally relevant pH and temperature conditions. The primary degradation products are hydrazine and p-Toluenesulfonic acid.

Once released into the water environment, p-TSH will readily - due to hydrolysis - be degraded into primarily hydrazine and p-Toluenesulfonic acid

Some retention of the waste water within in the industrial settings can be expected. The travelling time from p-TSH is released into waste water until arrival in the STP can vary quite much - in dependence of the distance to plant and the flow velocity. Typically, the flow velocity in the sewer is about 1 m/s, and with an average distance between the point of discharge and STP of 10 km, a retention time in the sewer of approximately 3 hours is calculated. In the sewer, a pH above 7 is usual (in order to limit the concentration of free H2S and to limit the corrosion due to the presence of sulfuric acid).

The overall retention time in a standard SimpleTreat sewage treatment plant (STP) is approximately 15 hours. Overall, a total retention time of 1 day = 24 hours is assessed to be a reasonable value to apply for the risk assessment. A pH between 7 - 8 is expected in the sewer and the sewage treatment plant.

In conclusion, a total hydrolytic transformation of approximately 65% before final discharge into the environment is assessed to be a reasonable value to use for the environmental risk assessment.