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Environmental fate & pathways

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Hydrolysis

A hydrolysis study performed according to OECD 111 (Hydrolysis as a function of pH) Guideline is available for (Volic, 2018).

  

Results from the preliminary test (Tier 1) showed that at each pH value (pH 4, pH 7 and pH9) <10% hydrolysis of the test item was observed after 5 days, thereby demonstrating that the half-life time of the test item at 25°C is >1 year. According to the guideline, performance of the main study (Tier 2) was not required and it is concluded that TMEDA is hydrolytically stable.

Biodegradation

A ready biodegradability study performed according to the OECD 301B (CO2 Evolution Test) Guideline is available for TMEDA (Flach, 2018).

Disparate degradation of TMEDA was observed in the triplicate vessels containing the test substance. No degradation (negative degradation, implying CO2 yield below the background recorded in the blanks) was observed in two of the vessels throughout the entire incubation. The third replicate showed a similar lack of CO2 production up to and including Day 21, but abruptly reached 32.9% ThCO2 yield on Day 28 and 36.5% ThCO2 after terminal acidification, indicating late-onset biodegradation during the final week of the test. Since measured CO2 yield did not reach 60% ThCO2 within 28 days, it may be concluded that TMEDA is not readily biodegradable.

Given the timing of the onset of CO2 production in the third replicate, it is not possible to determine whether biodegradation had reached a plateau by the end of the incubation, or whether it was still in progress at the time when biological activity was stopped by acidification.  However, the indication of significant biodegradation in the third replicate does suggest that more extensive and consistent degradation might occur under extended incubation conditions. TMEDA may be considered to be inherently biodegradable, not fulfilling specific criteria.  

Adsorption / desorption

The experimentally determined n-octanol/water partition coefficient (log Pow) of TMEDA at 20.2 ºC was -0.13. Low adsorption potential is therefore assumed and in accordance with Column 2 of REACH Annex VIII, an adsorption/desorption study does not need to be conducted given that the adsorption potential of the substance is related to this parameter.

Additional information