Triethyl citrate

Endpoint summary

Additional information

Biodegradation in water

Triethyl citrate was tested for its biodegradability potential according to EU method C.4 -D and OECD Guideline 301 F (Feil, 2010). Sodium benzoate (purity of 100 %) was used as reference compound. Also a toxicity control (test item and reference compound mixed) was run in parallel, to ensure, that the chosen test concentration was not inhibitory to microorganisms. The mean biodegradation after 28 days of the test substance was 78 % (ThOD NH4), further the 10 day window criterion was passed and therefore it is considered to be readily biodegradable. The reference item sodium benzoate was sufficiently degraded to 85 % after 14 days and to 88 % after 28 days of incubation, thus confirming the suitability of the aerobic activated sludge inoculum used. Furthermore, the test item was found to be not inhibitory to the aerobic activated sludge micro organisms and all validity criteria of the test method were met.

Biodegradation in water and sediment

Simulation testing on ultimate degradation in surface water, information requirement 9.2.1.2 in Annex IX, does not need to be conducted, as triethyl citrate (TEC) is considered to be readily biodegradable. The mean biodegradation after 28 days of the substance was 78%, the 10 day window criterion was passed from day 4 until day 14 [OECD Guideline 301 F, 2010].

Simulation testing on ultimate degradation in sediment, information requirement 9.2.1.4 in Annex IX, does also not need to be conducted, as it has been shown in soil biodegradation tests with the structural analogue acetyl tributyl citrate (CAS 77-90-7; ATBC) that the test substance is readily biodegradable.

The hazard assessment of TEC reveals neither a need to classify the substance as dangerous to the environment, nor is it a PBT or vPvB substance, nor are there any further indications that the substance may be hazardous to the environment. Therefore, a simulation test on biodegradation in surface water and sediment is scientifically not justified.

Biodegradation in soil

Two experimental results are available regarding biodegradation in soil for triethyl citrate. Both tests are conducted according to US Guidelines, whereby the methodological details, test conditions and results are reported in sufficient detail.

One experiment was conducted according to EPA OPPTS 835.3300 and ASTM D5988, concluding that the test substance can be considered as readily biodegradable in soil (Farrell, 2000). The required time for achieving 50 % mineralisation (t50) or 60 % mineralisation (t60) increased as the substance concentration in the soil increased. Nevertheless, at all substrate concentrations, net mineralisation of triethyl citrate was greater than that of the positive control (cellulose). Moreover, biodegradation of the TEC met or exceeded the ‘pass levels’ defined in the ASTM, FDA, and EPA guidelines.

Another experiment regarding ultimate biodegradation was conducted according to ASTM D5338 and ASTM D5988, whereby actively aerated compost was used as inoculum (Farrell, 2000), where the mineralisation of the test substance reached 64.9 % ThCO₂in 45 days. Both the TEC and cellulose reference achieved total, net mineralisation values ≥ 50 % ThCO₂during the 45-day test exposure, cellulose was the only test material to exceed the 60 % ThCO₂pass level defined in the ASTM guideline during the test exposure. Nevertheless, the calculated t₆₀for the TEC was 53 days – well within the time limit defined in ASTM Standard D 6002 (i.e., during a test exposure of up to 180 days).