3α,7α-dihydroxy-12-oxo-5β-cholan-24-oic acid

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

8. PBT AND vPvB ASSESSMENT

 

8.1. Assessment of PBT/vPvB properties

 

The assessment of PBT/vPvB properties has been done on the basis of the data available from the testing programme as well as from some calculated approaches.

 

8.1.1. Persistent assessment

 

To evaluate the persistence of the five bile acids (ursodeoxycholic acid, cholic acid, chenodeoxycholic acid, 7-ketolithocholic acid and 12-ketochenodeoxycholic acid)a ready biodegradability study has been carried out and results have been used in a read-across approach to evaluate the persistence in water of the other bile acids. In the experiment,ursodeoxycholic acid reached 53.4% of degradation after the 10-d window, and 82% after 28 days. The test item and the other bile acids,although they are not used in detergents,are surfactants as defined in Regulation 648/2004/EC: “any organic substance and/or mixture used in detergent, which has surface-active properties and which consist of one or more hydrophilic and one or more hydrophobic groups of such a nature and size that is capable of reducing the surface tension of water, and of forming spreading or adsorption monolayers at the water-air interface, and of forming emulsions and /or microemulsions and/or micelles, and of adsorption at water-solid interfaces”. Therefore, a surfactant shall be considered as biodegradable if the level of biodegradability is at least 60% within 28 days, irrespectively from 10-day window principle.

To determinate the abiotic degradation hydrolysis of bile acids, a test on ursodeoxycholic acid has been performed according to C.7 method in Council Regulation (EC) No 440/2008 of 30 May 2008 and OECD guideline No. 111. The results of the preliminary test showed that less than 50% of the test item has been hydrolysed in 2.4 hours at, and that less than 10% of the test item has been hydrolysed after five days for the three pH values, the full test was not performed. Therefore, according to guideline dispositions, the full test was not performed and it can be concluded that the abiotic degradation hydrolysis of ursodeoxycholic acid is lower than 10% after 5 days at pH values 4, 7 and 9.

Therefore, according to a read-across approach, bile acids are not expected to hydrolyze if released into the environment.

As a result of the previous considerations, the five bile acids, if released into the aquatic compartment, will not undergo to significant hydrolysis, but it will rapidly biodegraded.

Therefore the substances do not meet the criteria of Annex XIII of Regulation EC 1907/2006 for the classification as “Persistents”.

  

8.1.2. Bioaccumulation assessment

 

As a result of the values of logK_OW, and considering the low to moderate BCFs and the available toxicokinetics data, the five bile acids are not expected to bioaccumulate in aquatic organisms.

On the basis of the above consideration, the substances are not expected to meet the criteria ofAnnex XIII of Regulation EC 1907/2006 for the classification as “Bioaccumulative”.

8.1.3. Toxicity assessment

 

Results of the acute toxicity studies on aquatic organisms showed that ursodeoxycholic acid and, according to a read-across principle cholic acid, 7-ketolithocholic acid and 12-ketochenodeoxycholic acid, have a moderate to low aquatic toxicity. Considering that bile acids are also readily biodegradable and therefore the substances will be rapidly removed from the aquatic compartment, they are not a cause of concern.

Furthermore, considering the results of the toxicological assessment, no toxic properties have been observed for the previsous bile acids.

On the basis of the above consideration, it can be reasonably assumed that the substances do not meet the criteria of Annex XIII of Regulation EC 1907/2006 for the classification as “Toxic”.

  

8.1.4. Summary and overall conclusions on PBT or vPvB properties

 

Although environmental emissions are not foreseen in view of their use as intermediate under controlled conditions,, the five bile acid are considered to be readily biodegradable if released in water. Moreover, the substances are not expected to bioaccumulate and they are expected to be of low toxicity for aquatic organisms, as indicated by the short-term ecotoxicity studies on fish, crustaceans and algae.

In conclusion, considering all the available data, the substances do not meet the criteria ofAnnex XIII of Regulation EC 1907/2006 for the classification as “Persistent”, “Bioaccumulative” and “Toxic”. Therefore, ursodeoxycholic acid, cholic acid, 7-ketolithocholic acid and 12-ketochenodeoxycholic acidarenot considered to be neither PBT nor vPvB substances.

 

8.2. Emission characterization

Because the substances do not fulfil the PBT and vPvB criteria, no emission characterisation is performed. Furthermore on the basis of the exposure assessment, no significant release to environment is expected during the lifecycle of the substance.

Likely routes of exposure:

Bile acids (ursodeoxycholic acid, cholic acid, chenodeoxycholic acid, 7-ketolithocholic acid and 12-ketochenodeoxycholic acid) are used as intermediates in the synthesis of other substances, under controlled conditions.No significant release to the environment is expected, then human exposure is evaluated as unlikely and not significant.