Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Di-C12-18 alkyldimethyl ammonium chloride is poorly soluble in water and has a strongly adsorbs to negatively charged surfaces such as suspended matter, vessels or organic material (including dissolved organic matter such as humic acids). Standard guideline studies and guidance documents are not fully appropriate to test cationic surface-active substances like the dialkylquats as these apply rather to normal hydrophobic chemicals, and do not take into account the low bioavailability of dialkylquats under environmental conditions. Aquatic ecotoxicity tests performed in river water are therefore considered to assess the aquatic environmental risk more realistically for quaternary ammonium compounds as the use of river water in the effect assessment compensates for the missing prediction of the bioavailability in the exposure assessment. Aquatic ecotoxicity tests performed in river water are therefore considered as higher tier tests when compared to aquatic ecotoxicity tests performed in reconstituted lab water. Aquatic ecotoxicity tests performed in river water were therefore selected to allow a PECaquatic, bulk/PNECaquatic, bulk approach. This is considered to be conservative but more environmentally realistic than the standard method. This approach is thus 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, 2003).

 

No experimental data on short- or long-term toxicity to fish, short- or long-term toxicity to aquatic invertebrates and toxicity to algae are available for the target substance. However, studies are available for the closely related source substances DODMAC and DTDMAC. A justification for read-across is attached to IUCLID section 13.

 

Short-term toxicity to fish

Several studies are available for the closely related source substancesDODMAC andDTDMAC.

Depending on species tested and experimental conditions (river water, well water) the 96 h LC50 ranges from 0.29 to > 24 mg/L. The key study that has been selected was obtained in river water with a total organic carbon content of 4.6 mg/L and a 96 h LC50 of 21.3 mg/L.

From QSAR data it is deduced, that the target substance should be expected to be more toxic than the source substance DODMAC, and a factor of approx. 2 should be applied to the LC50 obtained with DODMAC. Thus, the 96 h LC50 ofthe target substanceDi-C12-18 alkyldimethyl ammonium chloride is considered to be 10.65 mg/L.

 

Long-term toxicity to fish

Embryo larval tests were conducted with DTMAC in Pimephales promelas in filtered well water and natural river water. In river water the NOEC for the most sensitive parameters hatchability and mean weight of larvae was 0.23 mg/L after 33 days test duration versus 0.053 mg/L

From the QSAR data on short-term toxicity it was deduced, that the target substance should be expected to be more toxic than the source substance DTDMAC, and a factor of approx. 2 should be applied to the NOEC obtained in this study. Thus, the NOEC ofthe target substanceDi-C12-18 alkyldimethyl ammonium chloride is considered to be 0.027 mg/L.

 

Short-term toxicity to aquatic invertebrates

Acute toxicity to daphnids varied with the type of dilution water used in the toxicity tests. In laboratory dilution water, the 48-h LC50 for DODMAC was 0.16 mg/L.The key value used was obtained in river water and was 3.1 mg/L.

From the QSAR data it is deduced, that the target substance should be expected to be more toxic than the source substance DODMAC, and a factor of approx. 2 should be applied to the LC50 obtained with DODMAC. Thus, the 48 h EC50 ofthe target substanceDi-C12-18 alkyldimethyl ammonium chloride is considered to be 1.55 mg/L.

 

Long-term toxicity to aquatic invertebrates

The no observed effect concentration (NOEC) for daphnids exposed to 14C-labeled DODMAC in river water was determined to be 0.38 mg/L

From the QSAR data on short-term toxicity it was deduced, that the target substance should be expected to be more toxic than the source substance DODMAC, and a factor of approx. 2 should be applied to the NOEC obtained in this study. Thus, the NOEC ofthe target substanceDi-C12-18 alkyldimethyl ammonium chloride is considered to be 0.19 mg/L.

 

Toxicity to algae and cyanobacteria

The key study selected for the assessment of toxicity to algae was obtained in river water. The NOEC value was 0.062 mg/L

From the QSAR data on short-term toxicity to fish and Daphnia (no model is available for algae) it was deduced, that the target substance should be expected to be more toxic than the source substance DODMAC, and a factor of approx. 2 should be applied to the NOEC obtained in this study. Thus, the NOEC ofthe target substanceDi-C12-18 alkyldimethyl ammonium chloride is considered to be 0.031 mg/L.

 

Toxicity to microorganisms

In a 3 hour toxicity study conducted according to OECD Guideline 209 (2010) using the cultures of activated sludge of a predominantly domestic sewage treatment plant, the 3 h NOEC of Di-C12-18 alkyldimethyl ammonium chloride was 10 mg a.i./L. The 3 h EC10 is 28.5 mg a.i./L, and the EC50 is 127 mg a.i./L.

 

Conclusion

The most sensitive species was algae. The NOEC of the target substance Di-C12-18 alkyldimethyl ammonium chloride was 0.031 mg/L. This value is used to derive the PNECs.

 

The substance is not readily biodegradable. The measured BCF for the closely related substance DODMAC is 13 L/kg and therefore the bioconcentration potential is very low. The bioaccumulation criterion (BCF >= 100 L/kg) is not fulfilled.

 

Therefore. based on the results above Di-C12-18 alkyldimethyl ammonium chloride is classified as Aquatic acute category 1 (M-factor 10) and Aquatic chronic category 1 (M-factor 1).