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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

HHCB does not mineralise under the conditions in screening tests for readily biodegradation in OECD TG 301 studies (e.g. OECD TG 301B study Jenkins 1991).

Key value for chemical safety assessment

Biodegradation in water:
not biodegradable
Type of water:
freshwater

Additional information

Modelled data and data available


According to (EPI) Suite v4.119 (EPA, 2011) BIOWIN models of the EPA do not indicate readily biodegradation for HHCB (BIOWIN models 1, 2, 5 and 6): all values are < 0.5. BIOWIN model 2 and 6 for non-linear biodegradability and BIOWIN 3 for ultimate biodegradation predict for HHCB: < 0.5 and < 0.5 and < 2.25 values, respectively. These values can be indicative for ‘persistency’ according to ECHA PBT guidance (R.11, page 62). BIOWIN 4 predicts primary biodegradation within days (value 4) to weeks (value 3) for HHCB which has the value of 3.08.


The removal of HHCB was simulated in EPISuite using the Sewage Treatment Plant model, BIOWIN output (as presented in the STP help-file) a. Based on the physio-chemical properties of HHCB, the model predicts total removal of HHCB at 96.6% in a aerobic waste water treatment plant with biodegradation accounting for 26% and sludge adsorption accounting for 70.6%. Loss via volatilization was modeled to be negligible.


Biotic degradation-screening data:


HHCB does not mineralise under the conditions in screening tests for readily biodegradation in OECD TG 301 studies (e.g. OECD TG 301B study Jenkins 1991). The possibility of primary degradation is also found in literature. From the available degradation studies and literature HHCB will break down into HHCB-lactone and to HHCB-hydroxylated-carboxylic acid presented in the table below (Franke et al. 1999; Federle et al. 2002 and 2003; and Berset et al. 2004). The first metabolite is an oxidation next to the ether bond resulting in a lactone, which is an ester. This can be an abiotic or biotic process (Franke et al., 1999). This ester can subsequently be cleaved by carboxylesterases (a biotic process) which are ubiquitous present in the environment resulting in a carboxylic-acid and a primary alcohol (Wheelock et al., 2008): HHCB-hydroxylated-carboxylic acid, which is the 3rd structure in the table. 


The table presents a representative of HHCBs constituent and two of its metabolites. HHCB-lactone is the first oxidation product of HHCB and HHCB-hydroxylated-carboxylic acid is a subsequent metabolite as found in several studies.










































Names



HHCB



HHCB-lactone



HHCB-hydroxylated-carboxylic acid



 



Parent



First oxidized metabolite



Second oxidized metabolite



Chemical structure


   

Smiles



CC1(C)c2cc3COCC(C)c3cc2C(C)(C)C1C



CC1(C)c2cc3C(=O)OCC(C)c3cc2C(C)(C)C1C



O=C(O)c1cc2c(cc1C(C)CO)C(C)(C)C(C)C2(C)C



 



C18H26O



C18H24O2



C18H26O3



MW



258



272



290



Reference list


Berset, Jean-Daniel, et al. "Considerations about the enantioselective transformation of polycyclic musks in wastewater, treated wastewater and sewage sludge and analysis of their fate in a sequencing batch reactor plant." Chemosphere 8 (2004): 987-996.


Federle, T. W., N. R. Itrich 2003. Biodegradation of Galaxolide (HHCB) in Activated Sludge. Notebooks: ITS-257, ITL-417. Proctor and Gamble Central Product Safety Division/Product Safety and Regulatory Affairs Environmental Science Department, OH


Federle, T. W., N. R. Itrich, D. M. Lee, and D. Langworthy. 2002. Recent Advances in the Environmental Fate of Fragrance Ingredients. Presentation and poster of Proctor & Gamble presented at SETAC 23rd Annual Meeting, Salt Lake City, USA (as cited in EC, 2008).


Franke, Stephan, et al. "Enantiomeric composition of the polycyclic musks HHCB and AHTN in different aquatic species." Chirality: The Pharmacological, Biological, and Chemical Consequences of Molecular Asymmetry 10 (1999): 795-801.


Jenkins, W. R., 1991. Abbalide: Assessment of its Biodegradability, Modified Sturm Test. Life Science Research Report 90/BAK003/1361. Bush Boake Allen, Inc. (as cited in EC, 2008).


Wheelock, C.E., Philips, B.M., Anderson, B.S., Miller, J.L., Miller, M.J., and Hammock, B.D., 2008, Application of carboxylesterase activity in environmental monitoring and toxicity identification evaluations, (TIEs), in Reviews of Environmental Contamination an Toxicology, ed. Whitacre, 117-178, D.M., Springer.

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