Quaternary ammonium compounds, bis(C16-18 and C18-unsatd. alkyl)dimethyl, chlorides

Long-term toxicity to fish

Description of key information

Toxicity figure based on river water testing.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

0.23 mg/L

Additional information

Read across for DTDMAC from structurally similar Quats DHTDMAC/DODMAC can be applied and the corresponding effect data form DHTDMAC/DODMAC used for DTDMAC as well.

In the Endpoint Summary Aquatic toxicity (IUCLID Chapter 6.1) an Overview table with the available chronic fish tests is given. From the EU Risk Assessment DODMAC (EU, 2002) the following discussion on Fish toxicity is available:

Chronic fish toxicity

To assess the long-term toxicity of DHTDMAC (71.4% active ingredient, 8% MTTMAC) embryo larval tests were conducted withPimephales promelasin filtered well water and natu­ral river water (EG & G Bionomics, 1982; Lewis & Wee, 1983). Exposure was initiated within 48 hours after fertilization and continued through 30 days post hatch in a flow-through system. In well water the most sensitive parameters were mean percent survival, length and weight of larvae. The NOEC was 0.053 mg/l (measured concentration) after 34 days test duration. 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. The river water (TownRiver) had the following characteristics: pH = 6.4 - 6.9, total hardness = 62 mg/l CaCO3, 9.4 mg/l suspended solids, 0.59 mg/l MBAS and triethyleneglycol was used as carrier solvent. The well water had a hard­ness of 28 -31 mg/l CaCO3, pH = 6.8-7.6 and isopropanol was used as carrier solvent. In well water the measured concentrations were equal to the nominal concentrations whereas in river water measured concentrations averaged 45-67% of the nominal concentrations.

In a study with natural water from Little Miami River, Ohio, newly hatched larvae ofPime­phales promelaswere exposed to DODMAC for 7 days (Versteeg & Shorter 1993). Measured concentrations up to 12.7 mg/l did not cause toxicity. However, the carrier solvent acidic methanol reduced the dry weight of the larval fish in a dose-dependent manner relative to con­trol fish so that the authors concluded that it would be better to test the substance in the absence of a carrier solvent. (river water quality, filtered: 5.4 mg/l total organic carbon, pH = 8.1 - 8.4, hardness = 171 mg/l CaCO3.) That this NOEC is higher than that derived by EG & G Bionomics possibly is caused by exposure in different periods in the life cycle and does not necessarily show that DHTDMAC is more toxic than DODMAC. (DODMAC was synthesized by a special route which ensures no MTTMAC.)