2,9-dichloro-5,12-dihydroquino[2,3-b]acridine-7,14-dione

Endpoint summary

Description of key information

Hydrolysis

The abiotic degradation of the substance cannot be determined, because there are no functional groups present in the molecule which could undergo hydrolytic cleavage in aqueous media (e.g. ester, ether or amide functions). Therefore, the study is scientifically not necessary.

In addition, the pigment is practically not soluble in water (water solubility: 14.5 µg/L)

Nevertheless, for the test item, the potential for hydrolytic degradation had been tested according to OECD-guideline for testing of chemicals no. 111 and E.U-method C.7 according to GLP (reliability category 1).

The test could not proceed further as to the first recovery-experiments after preparation of the buffered solutions of the test substance. In spite of trying 4 different co-solvents to increase dissolution of the test item in the buffer solutions all the resulting solutions were too dilute to be detectable by analytics based on HPLC/UV-Vis-spectroscopy after chemical derivatization (LOQ about 0.007 µg/mL).

Therefore, solubility of the test item in buffered solutions is far too low to allow for testing of the potential for hydroyltic degradation.

 

Biodegradation, screening tests

 

Two biodegradation tests with read across substances are available with the same result.

he ready biodegradability in the Manometric Respirometry Test was determined with a non adapted activated sludge for the test item over a period of 28 days. The study was conducted from 2006-06-20 to 2006-07-18 according to OECD guideline 301 F at DR.U.NOACK-LABORATORIEN, D-31157 Sarstedt. The test item concentration selected as appropriate was 40 mg/L, corresponding to a ThOD of 87.2 mgO₂/L in the test vessel. The oxygen was depleted by the respiration of bacteria and the degradation was followed by measuring the oxygen concentration. The biodegradation is therefore expressed as the percentage BOD and was calculated for each study day.

The mean oxygen depletion in the inoculum control came to 33.8 mgO₂/L after 28 days. In order to check the activity of the test system sodium benzoate was used as functional control. The pass level > 60 % was reached after 3 days. The biodegradation rate came to 92 % after 28 days.

In the toxicity control containing both test and reference item 39 % degradation occurred within 14 days. The degradation of the reference item was not inhibited by the test item.

The 10 % level (beginning of biodegradation) was not reached until 28 days. The mean biodegradation remained at 0 %.

The validity criteria of the guideline are fulfilled.

The test item must be regarded as not readily biodegradable in the 10-d-window and after 28 days.

In addition, the second biodegradation test with a read across substance is available with the same result.

In a ready biodegradability test based upon CO2-evolution (reliability category 1, compliant to GLP) no biodegradation could be observed at the end of the test period (28 days). The reference substance (sodium benzoate) was thoroughly degraded at day 28 and to 79% at day 14 proving the suitability of the activated sludge used. On the other hand, lack of biodegradation was not caused by toxicity of the test item as the toxicity control with both, the test item and the reference substance, showed no inhibition compared to the procedural controls with the reference substance only. 

 

Biodegradation, simulation tests

The testing of biodegradation in water: simulation testing on ultimate degradation in surface water was waived according to "column 2" in Annex IX of REGULATION (EC) No 1907/2006 (CSA does not indicate need for further investigations. Substance considered to be not readily biodegradable, no further relevant information expected from additional testing) In addition the substance is hig´hly insoluble in water.

Regarding sediment simulation testing a second waiver is available, because the substance is not supposed to be directly applied to sediment. Based on the PC properties of the substance (extremely low solubility in water and octanol), a low adsorption potential is indicated. As a consequence, a binding/transfer to sediment is not expected. Therefore, it can be assumed that there is no direct and indirect exposure to the sediment

 

 

Biodegradation in soil

The substance is not supposed to be directly applied to soil. Based on the PC properties of the substance (extremely low solubility in water and octanol), a low adsorption potential is indicated. Therefore, binding to sewage sludge is unlikely and as a consequence a transfer to the soil compartment is not expected. Therefore, it can be assumed that there is no direct and indirect exposure to the environment 

In addition, the test is waived according to "column 2" in Annex IX of REGULATION (EC) No 1907/2006 (CSA does not indicate need for further investigations. Substance considered to be not readily biodegradable, no further relevant information expected from additional testing)

 

Bioaccumulation

The study is scientifically not necessary and does not to be conducted because the substance has a low potential for bioaccumulation based on a log Kow < 3.

 

Adsorption/Desorption

The study does not need to be conducted because substance has a low octanol water partition coefficient and the adsorption potential of this substance is related to this parameter.

Nevertheless, the estimation of the adsorption coefficient Koc of a read across substance had been applied according to the OECD Guideline 121

The poor solubility of the test item in water as well as in other solvents precluded the deduction of useful results. Using different solvent mixtures, partial dissolution of the test item had been possible. Elution from the HPLC-column, however, proved to be impossible in spite of different solvent systems used. Most probably, the test item had precipitated on the column. Therefore, Koc for the test item cannot be determined using the estimation method based on HPLC.