Distillation residue, butyl alcohols production, rectification

Endpoint summary

Additional information

The substance is a UVCB-substance. Due to the complex composition of the substance there are a lot of technical difficulties related to the testing of the substance. Different constituents have different physical-chemical properties (e. g. solubility, vapour pressure, octanol/water partition coefficient) and biodegradation. Because the composition of this substance is not easily identifiable, the grouping methods and read-across was regarded as an unsuitable approach for this substance.

According to the vapour pressure measurement (0 kPa), the substance is non volatile at room temperature. It is water soluble (2-9 g/L) but most probably also contains constituents having low solubility in water. This conclusion is based on the results obtained by the flask method. During the testing, two phases were detected, the upper fraction with alcohols and the lower fraction with clear solution. According to experimental data on the partition coefficient study (EC 444/2008), this substance might contain substances having potential for adsorption and bioaccumulation. The HPLC method indicated peaks corresponding log Kow values of 1.8 to 5.8, but also constituents corresponding the log Kow values of 6.4 up to 7.5.

Substance is hydrolytically stable and the half-life estimated by the preliminary study (OECD 111) at three pH-values is over one year. This substance was inherently biodegradable in water (OECD 301B). Some biodegradation occurred (biodeg-% 49.6) but the criteria for ready biodegradability was not fulfilled (failing 10 days-window).

Due to differences in physical-chemical properties between the components, it is difficult to achieve a homogeneous solution by direct addition of the test substance into the test medium. Therefore water accommodated fractions (WAFs) were prepared for aquatic toxicity testing. The WAF of the multi-component substances contains only the fraction that is dissolved or present as a stable dispersion or emulsion. The exposure was expressed as the loading rate (mass to volume ratio of the mixture to medium).

Aquatic acute toxicity effects of the substance were tested with V. fischeri, D. magna, algae, fish and STP micro-organism toxicity tests. The substance had acute toxicity effects on algae, water fleas and luminescent bacteria at exposure loading rates (EL50) range of 10-100 mg/L. However, it was not an inhibitory to activated sludge microorganisms at maximum test concentration of 100 mg/L. PNEC values were determined based on the test results. Application of loading rate is not recommended for PNEC derivation but other methods were not possible for the substance. Long-term toxicity testing was not considered necessary at this stage of the chemical safety assessment because testing is not technically feasible for this kind of complex UVCB substance.