2,3-epoxypropyltrimethylammonium chloride

Endpoint summary

Additional information

Abiotic degradation:

Hydrolysis of EPTAC to DIOL at pH conditions relevant for the environment (ca. pH 7.8) takes approximately t^½= 177 days at 12°C.

Biodegradation:

According to existing biodegradation study results EPTAC is not readily biodegradable. Two reliable tests are available: one regarding inherent biodegradability (Zahn-Wellens test), and the other on STP degradation simulation of EPTAC. In the Zahn-Wellens test, 61% of the substance was mineralized after 28 days and 94% after 42 days, showing moderate degradation in this inherent study. In the 135-day STP simulation test 15 ± 9.7% primary degradation was observed in 6 hours (sludge retention time 6 hours). These results indicate that competent degraders of EPTAC exist and they are not very rare. In conclusion, available data shows that degradation rate of EPTAC in the environment is slow and the screening P criterion is fulfilled regarding biodegradation.

Bioaccumulation:

No experimental test result on bioaccumulation of EPTAC is available. Bioconcentration factors (BCF) for fish and earthworm can in principle be estimated according to equations reported in EU TGD (rev3) using known Kow. However, the equation in the TGD is relevant only for substances with a Log Kow 1–6 (for EPTAC Log Kow < -1.3). In addition for certain types of chemicals e.g. those which ionise in water, Log Kow values may not be suitable for calculation of a BCF value. Therefore precaution should be taken to interpret the results from the calculations. As reported in the EU RAR, BCFs calculated according to EUSES are: BCF_Fish =1.41 L/kg and BCF_Worm = 3.34 kg/kg. Based on calculated BCFs no significant bioaccumulation is expected.

Transport and Distribution:

The theoretical distribution of EPTAC between four environmental compartments at equilibrium has been calculated using the fugacity model EQC v.1.1 (Mackay level I). The results clearly indicate that EPTAC will partition to water almost totally (100 %) and distribution to other compartments is negligible (soil 3.53 x 10^-5%, sediment 7.83 x 10^-7% and air 3.59 x 10^-6%). Similar results can been seen from Level III fugacity model EPIWIN v3.20, where 99.8 % of the substance remain in water, when the release is to water compartment.

Adsorption/desorption:

As reported in the EU RAR, since measured values for adsorption of EPTAC to soil, sediment or suspended matter are not available, the calculated value for the chlormequat-chloride could serve as a realistic surrogate value for EPTAC (with known limitations). Like in the chlormequat-chloride, the positively charged quaternary nitrogen group in EPTAC is adsorbed by ion exchange mechanism to anionic groups of sediment mineral particles and to organic matter. Therefore this surrogate value, sediment-water partition coefficient (Kp sed) 67 L/kg, could better describe the adsorption of EPTAC to sediments than Kp derived from Log Kow. Adsorption to suspended matter is usually assumed to be two times higher than adsorption to sediment due to two times higher organic carbon content of solids. Based on additional test results, the adsorption of EPTAC is not assumed to correlate highly on the organic carbon content. Thus, the same Kp value (67 L/kg) could be used for suspended matter. Taken the same arguments presented above on sediment it could be possible to use a Kpsoil from chlormequat-chloride (2.4) to describe adsorption of EPTAC to soil. However, as there is information on EPTAC adsorption to STP sludge, an Koc value has been derived for EPTAC from this study. This Koc (53.8 L/kg) can be used to estimate Kp values for EPTAC in soil, suspended matter and sediment. Partition coefficients estimated from the measured Koc for soil, suspended matter and sediment will be used in further calculations.