Reaction mass of 2-(1,1-dimethylpropyl)anthraquinone and 2-(1,2-dimethylpropyl)anthraquinone

Endpoint summary

Additional information

- Hydrolysis:

The study was not performed since the substance is highly insoluble in water (water solubility of the test substance is 0.15 mg/l) and based on the structure, hydrolysis is not expected.

 

- Photolysis:

The direct photolysis of the two isomers of 2-amylanthraquinone was evaluated in a study according to the OECD 316 guideline. A tiered approach was followed. For 2-amylanthraquinone (A) the predicted environmental photolytic half-life varies between 1123 days at 30ºN in the summer and 20027 days at 60ºN in the winter. For 2-amylanthraquinone (B) the predicted environmental photolytic half-life varies between 148 days at 30ºN in the summer and 2595 days at 60ºN in the winter. The environmental photolytical half-life times are so high that photolysis is not assumed to be a relevant degradation process in the environment.

From the analysis of the stock solutions via LC/MS it was proposed that the peaks annotated as 2-amylanthraquinone (A) and 2 -amylanthraquinone (B) during Tier 2 correspond to the isomers (2-(3-methylbutan-2-yl) anthracene-9,10-dione) and (2-(2 -methylbutan-2-yl) anthracene-9,10-dione), respectively. A third isomer has also been proposed to be present, 2-(2-(2,2 -dimethylpropyl) anthracene-9,10-dione. The photolytic degradation of 2-amylanthraquinone produced at least six transformation products which were not successfully identified due to low initial concentrations, solubility and the number of transformation products that were separated during the analytical run. All transformation products observed appear to be short lived and transitory indicating that over time the residual related compounds were likely to be a mixture of many complex compounds.

 

- Biodegradation:

A ready biodegradability study of 2-amylanthraquinone in a closed bottle test was performed for 56 days (OECD301D). The following biodegradation was observed during the study: 30% (5 days), 23 % (15 days), 18% (28 days) and 17% (56 days). It is concluded that the test substance is not readily biodegradable under conditions applied in this test.

In a manometric respirometry biodegradability study (OECD301F), under aerobic circumstances activated sludge, domestic, non-adapted (30 mg/l) was exposed to 20 and 50 mg/l test substance for 56 days. Oxygen consumption was measured as parameter for biodegradation estimation. This study incorporated the REACH technical guidance for assessing the biodegradability of poorly water soluble compounds. For example surfactants, silica gel and silicone oil were used to increase the bioavailability of 2 -amylanthraquinone. The substance is considered not biodegradable as less than 11% degradation was observed after 56 days of inoculum exposure. In a supporting study, limited described but from a reliable source, the substance is assessed to be non biodegradable in an OECD302C study (0% after 14 days).

Ready biodegradability of 2-amylanthraquinone was also studied in modified Sturm test for 28 days (OECD301B). The initial concentration of the test substance was 10 and 20 mg/L. The sludge was present in a concentration of 30 mg of solid substance per L medium. The test substance did not dissolve to any visually detectable extent and was still visible on the bottom of the flasks at the end of the test. Therefore, this study was disregarded.

A study was conducted according to OECD 301F with modifications for poorly water soluble substances and enhancements. Oxygen consumption of the sludges was extremely large, which resulted in no useful information on ready biodegradation. However HPLC measurements of the 2-amylanthraquinone concentration generated useful information on the primary biodegradation of the substance. With adapted sludge the primary degradation was about 98 % after 2 weeks, while a primary degradation of 70 % has been found after 2 months when non-adapted sludge was used.  The study is considered supporting.

Although no significant ultimate biodegradation was observed in the available screening tests it has been shown that 2-amylanthraquinone is primary biodegradable. Other anthraquinone derivates, like 2-ethylanthraquinone, are inherently biodegradable. Furthermore the UM-BBD Pathway Prediction System indicates that several aerobic biodegradation pathways of 2-amylanthraquinone are likely. This biodegradation pathway prediction system has been developed by theof(Fishbach et al., 2011). 

 

- Bioaccumulation:

Two studies on bioaccumulation and biomagnification in fish were available. The study on biomagnification in fish is considered to be not reliable, but the study on bioaccumulation in fish was performed comparable to the OECD305 test guideline. At a concentration of 0.05 mg/L, hence below the water solubility (0.15 mg/l) the BCF of the two components has a mean value of 1215 L/kg ww, which was used for risk assessment purposes.

 

- Adsorption/desorption:

In and OECD121 guideline study using a HPLC method, the Koc and log Koc values of the major components in 2-amylanthraquinone and of a minor component with a peak area > 1% are determined to be:

Minor component – peak 1: Koc = 1.5 x 10^3; log Koc = 3.18

Major component – peak 4: Koc = 3.1 x 10^4; log Koc = 4.49

Major component – peak 5: Koc = 3.7 x 10^4; log Koc = 4.57

For risk assessment purposes, the log Koc value of a major component is taken, in this case the log Koc of 4.49 was used, being a worst case value for the water compartment (lower value results in less adsorption to soil and thus more possible leaching to the groundwater). The values show that the substance will adsorp to soil/sediment particles.