Quaternary ammonium compounds, C12-18-alkylbis(hydroxyethyl)methyl, chlorides

Endpoint summary

Additional information

Quaternary ammonium compounds, C12-18-alkylbis(hydroxyethyl)methyl, chlorides are poorly soluble in water and have a strong tendency to adsorb to negatively charged surfaces such as suspended matter and test vessels or organic material (including dissolved organic matter such as humic acids). Quaternary ammonium compounds with long alkyl chains rank among the most difficult substances to test in environmental toxicology. Standard guideline studies are inappropriate to test substances with such properties and the current REACH Guidance Documents do not provide sufficient guidance concerning bioavailability and ecotoxicity testing for cationic surface-active substances like these quaternary ammonium compounds as these were written with neutral hydrophobic chemicals in mind, failing to take into account the lack of bioavailability that occurs in the environment with these substances.

The long-term aquatic ecotoxicity tests with Quaternary ammonium compounds, C12-18-alkylbis(hydroxyethyl)methyl were therefore performed in river water to allow a PECaquatic,bulk/PNECaquatic,bulk approach and are considered to be more environmentally realistic than the standard method.This approach is based on PEC estimations representing ‘total aquatic concentrations’.To characterize the risk to the aquatic compartment the PECaquatic,bulk is compared with the PNECaquatic,bulk derived from river water ecotoxicity studies (ECETOC, 2001).

The difficulties encountered with the standardised ecotoxicity tests for these surfactants are avoided by the use of river water tests.

For ecotoxicity tests performed with riverwater adsorption to suspended matter and DOC is acceptable and only adsorption to glassware should be accounted for. For a valid bulk approach test, the concentration-effect relationship should be based on the sum of adsorbed and dissolved substance in the volume of the medium tested. One of the advantages of the bulk approach tests with these difficult substances is that in the presence of suspended matter, humic acids and/or algae, the residual sorption to glassware will be negligible.The results of these bulk approach tests are therefore much easier to interpret. The PNECbulk provides a more environmentally realistic estimation than the PNEC based on dissolved concentrations in reconstituted lab water. The PNECbulk should be compared to the PECbulk. All effect values given are therefore based on the nominal test item concentrations.

For some aquatic toxicity endpoints, supporting information is obtained from the related Quaternary ammonium compounds, C14 alkylbis(hydroxyethyl)methyl, chlorides and Quaternary ammonium compounds, C12 alkylbis(hydroxyethyl)methyl. These substances have the same basic structure consisting of quaternary ammonium having one methyl, two ethoxy groups and one fatty acid derived alkyl chain. The only difference consists of differing chain lengths (range of C12 - C18 alkyl chains, or C12 and C14 alkyl chains pure, respectively). The available aquatic data seem to suggest that acute toxicity depends on chain length and saturation. Increasing chain length leads to a lower bioavailability and less toxicity to biota. Therefore it is considered justified to use read-across from data of substances with C12 or C14 chain to the substance with a range of various C12 – C18 alkyl chains. The read-across has been used solely as supporting information for the acute toxicity to aquatic invertebrates and algae. 

It should be noted that the 21d-EC50 for daphnia, river water has been included as a worst case for the short term EC50-daphnia, river water. The effect concentrations are based on the active ingredient content.

An overview of the most relevant results is presented in the table.

 

	CAS number	Result	Reference
Danio rerio OECD 203 KEY Study (Rel. 2)	70750-47-9	96h-LC50 = 1.84 mg a.s./L, reconst lab water	AkzoNobel, 1992
Daphnia OECD 202 KEY Study	22340-01-8 (C12 - supporting evidence) 70505 -47 -9	48h-EC50 = 0.74 mg a.s./L, reconst lab water 21d-EC50 = 0.465 mg a.s./L, river water	Mark, 1994 Scheerbaum, 2010
Pseudokircherniella subcapitata OECD 201 KEY Study	70505-47-9	72h-ErC50 = 0.414 mg a.s./L, river water 72h-ErC10 = 0.121 mg a.s./L, river water	Scheerbaum, 2010
Daphnia OECD 211 KEY Study	70505-47-9	21d-NOEC = 0.268 mg a.s./L Reproduction, 21d-EC50 = 0.465 mg a.s./L river water	Scheerbaum, 2010
Microorganisms OECD 209 Key Study	70505-47-9	3h-EC50 = 28.8 a.s mg/L 3h-EC10 =10.9 mg a.s./L	Geerts, 2010

 

Conclusion

Acute toxicity results are available for three taxonomic groups (fish, invertebrates and algae). Long term toxicity results are available for aquatic invertebrates and algae. As fish is clearly less sensitive than daphnia and algae towards the substance, no further long term testing with fish is proposed to avoid further vertebrate testing. Moreover cationic surfactants are known to have a low bioaccumulation potential based on their chemical structure. The very low bioaccumulation potential does not trigger the need for long term fish testing either. Therefore long term fish testing has been waived.