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Short-term toxicity to fish

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Endpoint:
short-term toxicity to fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
For details on endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “assessment report”.
Reason / purpose for cross-reference:
assessment report
Reason / purpose for cross-reference:
read-across source
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
21.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: river water fromDry Creek Fork (pH 8.4-8.6, Hardness 173 mg/L, TOC 4.6 mg/L)
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
36.2 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: river water from Little Miami River (pH 7.5-8.5, Hardness 175 mg/L, TOC 6.2 mg/L)
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
6.3 - 13.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: well water + humic acids
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
3.55 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: well water
Validity criteria fulfilled:
yes
Remarks:
Not all parameters according to OECD 203 are explicitly reported; daily renewal procedure as well as study design and reporting strongly suggests that validity criteria were met.
Conclusions:
In an acute fish toxicity study with the source substance DODMAC following EPA 600/4-85-013 (1985), two different river waters were used for the 96 h toxicity test on Pimephales promelas. The following results are relevant for the target substance DTDMAC (based on source nominal concentrations):
LC50 (96h) was 21.3 mg/L for the river water from Dry Fork Creek (4.6 mg/L TOC) and 36.2 mg/L for the river water from Little Miami River (6.2 mg/L TOC). The river waters differ mainly in the TOC content. The lower value of LC50 (96h) of 21.3 mg/L was taken for classification and labelling as well as the environmental hazard assessment. Reasoning is that the respective river has the lower TOC and therefore a less mitigating effect on toxicity. The MW difference between source and target substance is low (formally, a factor of 0.904 were needed to adapt effect concentrations to the target substance). Considering the overall variability observed as a function of the organic carbon content of test waters, the effect of the molecular weight difference between source and target on effect concentrations is negligible an thus no correction was performed.
Executive summary:

The study used as source investigated the 96 h acute toxicity towards freshwater fish using the source substance DODMAC in a study performed similar to OECD 203. The study results determined for the source substance were considered applicable to the target substance. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13 or find a link in cross reference “assessment report”.

Endpoint:
short-term toxicity to fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
For details on endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “assessment report”.
Reason / purpose for cross-reference:
assessment report
Reason / purpose for cross-reference:
read-across source
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
10.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: 95% CI: 8.3- 12.6
Remarks:
Town River Water (Plymouth Country, Massachusetts), ca. 13 mg/L susp. solids, ca. 1.3 mg/L TOC
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 24 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: different river water, not further specified: >24 mg/L and 14 mg/L given for LC50
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
ca. 1.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality (fish)
Remarks on result:
other: reconstituted water, AM from 6 different test results given, range: 0.62 to 3.0 mg/L
Remarks:
potentially different reconstituted water used
Conclusions:
Acute fish toxicity (96 h; Lepomis macrochirus; static; nominal) similar / equivalent to OECD 203 (1992), Lewis and Wee, 1983:
River water (susp. solids ca. 13 mg/L; TOC ca. 1.3 mg/L): LC50 (96 h) = 10.1 mg/L (96% CI: 8.3-12.6);
River water (susp. solids >= 50 mg/L): no mortality at 10.1 mg/L test item;
Reconstituted water: LC50 (96 h; AM over 6 results) = 1.35 mg/L.
Executive summary:

The study used as source investigated the 96 h acute toxicity towards freshwater fish using the source substance DHTDMAC in a study performed similar to OECD 203. The study results determined for the source substance were considered applicable to the target substance. Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13 or find a link in cross reference “assessment report”.

Description of key information

In an acute fish toxicity study with the source substance DODMAC following EPA 600/4-85-013 (1985), two different river waters were used for the 96 h toxicity test on Pimphales promelas. The following results are relevant for the target substance DTDMAC:

LC50 (96h) was 21.3 mg/L for the river water from Dry Fork Creek (4.6 mg/L TOC) and 36.2 mg/L for the river water from Little Miami River (6.2 mg/L TOC). The river waters differ mainly in the TOC content. The lower value of LC50 (96h) of 21.3 mg/L was taken for classification and labelling as well as the environmental hazard assessment. Reasoning is that the respective river has the lower TOC and therefore a less mitigating effect on toxicity. The MW difference between source and target substance is low (formally, a factor of 0.904 were needed to adapt effect concentrations to the target substance). Considering the overall variability observed as a function of the organic carbon content of test waters, the effect of the molecular weight difference between source and target on effect concentrations is negligible an thus no correction was performed.  

Further supporting information is available (Lewis and Wee, 1983) based on the source substance DHTDMAC. The following data are relevant for the target substance DTDMAC:

Acute fish toxicity (96 h; Lepomis macrochirus; static; nominal) similar / equivalent to OECD 203 (1992):

River water (susp. solids ca. 13 mg/L; TOC ca. 1.3 mg/L): LC50 (96 h) = 10.1 mg/L (96% CI: 8.3-12.6);

River water (susp. solids >= 50 mg/L): no mortality at 10.1 mg/L test item;

Reconstituted water: LC50 (96 h; AM over 6 results) = 1.35 mg/L.

Considering the lower TOC in river water used with source DHTDMAC (ca. 1.3 mg/L) compared with Dry Fork Creek water (TOC 4.6 mg/L) used with source DODMAC as well as the different species assessed, the difference in LC50 (96 h) values (10.1 mg/L vs. 21.3 mg/L) is plausible due to the known mitigating effect of suspended matter on the toxicity of dialkyl dimethyl quaternary ammonium compounds.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
21.3 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 acute fish tests is given. From the EU Risk Assessment DODMAC (EU, 2002) the following discussion on Fish toxicity is available:

Acute fish toxicity

The acute toxicity of DODMAC for fish was investigated in a study by Lewis & Wee, 1983. A static 96 h US EPA test was used with well water and Lepomis macrochirus (pH = 7.1 - 7.9, total hardness = 315 - 348 mg/l CaCO3). A LC50 of 1.04 mg/l was derived (nominal concentration of active ingredient). When the same test method was used for DHTDMAC and reconstituted laboratory waters the LC50-values ranged from 0.62 to 3.0 mg/l. In these cases it is not known whether different water qualities might have been used or which other test parameters were varied. These results demonstrate similar toxicities for DODMAC and DHTDMAC for Lepomis macrochirus.

Compared with the results described above the toxicity of DHTDMAC for Lepomis macrochirus was reduced in natural surface water which received municipal waste water effluent (Town River, Massachusetts: pH = 6.4 - 7.7, total hardness = 14 -38 mg/l CaCO3, 2-84 mg/l suspended solids, 0.04 - 0.59 mg/l methylene blue active substances - MBAS, 10-15 µg/l disul­fine blue active substances - DBAS). 96h LC50-values of 10.1 to > 24.0 mg/l were derived (Lewis & Wee, 1983). A combination with C12LAS reduced the adverse effects of DHTDMAC in laboratory water tests. The 96h LC50-values at molar ratios of DHTDMAC/ C12LAS ranging from 2:1 to 1:2 varied from 9.4 to 186 mg/l (nominal concentrations of active ingredient). In these tests of Lewis & Wee, 1983, no information is given on the purity of the test substance but isopropanol or methanol were added as carrier solvent.

In ECETOC, 1993, for different molar ratios of DHTDMAC/C12LAS the following 96h LC50-values forLepomis macrochirusare cited: 7.1 mg/l at 2:1; 17.6 mg/l at 1:2; 7.9-171 mg/l at 1:1 (no more details on test procedure, Procter & Gamble, 1974 - 1986).

The acute toxicity of DODMAC (97% purity, containing no MTTMAC) forPimephales promelaswas also investigated in different filtered natural river waters and well water enriched with different contents of humic acids (Versteeg & Shorter, 1992). Fish were exposed for 96 hours under static renewal conditions. In well water alone a LC50 of 3.55 mg/l (nominal) was derived (< 1 mg/l total organic carbon). In well water to which different amounts of dissolved humic acids extracted from natural rivers were added (1.6 - 2.2 mg/l total organic carbon) the corresponding LC50-values were 6.3 to 13.8 mg/l. In river water with a total organic carbon content of 4.6 mg/l (Dry Fork Creek,Ohio; pH = 8.4 - 8.6, hardness = 173 mg/l CaCO3) the LC50 was 21.3 mg/l. In another river with a total organic carbon content of 6.2 mg/l the LC50 was 36.2 mg/l (Little Miami River, Ohio; pH = 7.5 - 8.5, hardness = 175 mg/l CaCO3). In these tests the toxicity of DODMAC was positively correlated with the humic acid concentration and the total organic carbon content.

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.)