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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
This read-across is based on the hypothesis that source and target substances have similar toxicological properties because
• they are manufactured from similar or identical precursors under similar conditions
• they share structural similarities with common functional groups: quaternary ammonium and saturated or unsaturated alkyl chains with comparable length (corresponding to scenario 2 of the read-across assessment framework)

The read-across hypothesis is based on structural similarity of target and source substances. Based on available experimental data, including key physicochemical properties and data from acute toxicity, irritation, sensitization (human) and genotoxicity studies, the read-across strategy is supported by a quite similar toxicological profile of all substances.

Therefore, read-across from the existing ecotoxicity, environmental fate and toxicity studies conducted with the source substances is considered as an appropriate adaptation to the standard information requirements of the REACH Regulation for the target substance, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.

A justification for read-across is attached to IUCLID section 13.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See justification for read-across attached to IUCLID section 13.

3. ANALOGUE APPROACH JUSTIFICATION
See justification for read-across attached to IUCLID section 13.

4. DATA MATRIX
See justification for read-across attached to IUCLID section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across: supporting information
GLP compliance:
no
Nominal and measured concentrations:
Nominal concentration tested = 20 µg/L
Type:
BCF
Value:
256 L/kg
Basis:
non-edible fraction
Time of plateau:
14 d
Calculation basis:
steady state
Remarks on result:
other: Conc.in environment / dose:20 µg/L - Well water
Type:
BCF
Value:
94 L/kg
Basis:
non-edible fraction
Time of plateau:
49 d
Calculation basis:
steady state
Remarks on result:
other: Conc.in environment / dose:23 µg/L - River water
Type:
BCF
Value:
32 L/kg
Basis:
whole body w.w.
Time of plateau:
14 d
Calculation basis:
steady state
Remarks on result:
other: Conc.in environment / dose:20 µg/L - Well water
Key result
Type:
BCF
Value:
13 L/kg
Basis:
whole body w.w.
Time of plateau:
49 d
Calculation basis:
steady state
Remarks on result:
other: Conc.in environment / dose:23 µg/L - River water
Elimination:
yes
Parameter:
other: 93% of the test item was depurated after 14d
Depuration time (DT):
14 d
Validity criteria fulfilled:
not applicable
Conclusions:
The BCF values for bluegill were very low in river water (13 L/kg wwt), and slightly higher in well water (32 L/kg wwt). The BCF river water of 13 L/kg wwt was used in the EU Risk Assessment DODMAC (EU, 2002).
The relatively higher values in well water, whether based on residues in inedible tissue or in whole body, indicate the reduced bioavailability of the surfactants in surface water.
Endpoint:
bioaccumulation in aquatic species: fish
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification
Justification for type of information:
1. SOFTWARE
EpiSuite v4.11

2. MODEL (incl. version number)
BCFBAF v3.01

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
Trimethyl-dodecyl ammonium [Cl-].C[N+](C)(C)CCCCCCCCCCCC
Trimethyl-tridecyl ammonium [Cl-].C[N+](C)(C)CCCCCCCCCCCCC
Trimethyl-tetradecyl ammonium [Cl-].C[N+](C)(C)CCCCCCCCCCCCCC
Trimethyl-pentadecyl ammonium [Cl-].C[N+](C)(C)CCCCCCCCCCCCCCC
Trimethyl-hexadecyl ammonium [Cl-].C[N+](C)(C)CCCCCCCCCCCCCCCC
Trimethyl-octadecyl ammonium [Cl-].C[N+](C)(C)CCCCCCCCCCCCCCCCCC
Dimethyl-didodecyl ammonium (C 26) [Cl-].CCCCCCCCCCCC[N+](C)(C)CCCCCCCCCCCC
Dimethyl-ditridecyl ammonium (C 28) [Cl-].CCCCCCCCCCCCC[N+](C)(C)CCCCCCCCCCCCC
Dimethyl-ditetradecyl ammonium (C 30) [Cl-].CCCCCCCCCCCCCC[N+](C)(C)CCCCCCCCCCCCCC
Dimethyl-dipentadecyl ammonium (C 32) [Cl-].CCCCCCCCCCCCCCC[N+](C)(C)CCCCCCCCCCCCCCC
Dimethyl-dihexadecyl ammonium (C 34) [Cl-].CCCCCCCCCCCCCCCC[N+](C)(C)CCCCCCCCCCCCCCCC
Dimethyl-dioctadecyl ammonium (C 38) [Cl-].CCCCCCCCCCCCCCCCCC[N+](C)(C)CCCCCCCCCCCCCCCCCC
Tridodecyl-methyl ammonium (C 36) [Cl-].CCCCCCCCCCCC[N+](C)(CCCCCCCCCCCC)CCCCCCCCCCCC
Tritridecyl-methyl ammonium (C 39) [Cl-].CCCCCCCCCCCCC[N+](C)(CCCCCCCCCCCCC)CCCCCCCCCCCCC
Tritetradecyl-methyl ammonium (C 42) [Cl-].CCCCCCCCCCCCCC[N+](C)(CCCCCCCCCCCCCC)CCCCCCCCCCCCCC
Tripentadecyl-methyl ammonium (C 45) [Cl-].CCCCCCCCCCCCCCC[N+](C)(CCCCCCCCCCCCCCC)CCCCCCCCCCCCCCC
Trihexadecyl-methyl ammonium (C 48) [Cl-].CCCCCCCCCCCCCCCC[N+](C)(CCCCCCCCCCCCCCCC)CCCCCCCCCCCCCCCC
Trioctadecyl-methyl ammonium (C 54) [Cl-].CCCCCCCCCCCCCCCCCC[N+](C)(CCCCCCCCCCCCCCCCCC)CCCCCCCCCCCCCCCCCC


4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
- Defined endpoint: BCF
- Unambiguous algorithm:
Ionic compounds are predicted as follows:
log BCF = 0.50 (log Kow < 5.0)
log BCF = 1.00 (log Kow 5.0 to 6.0)
log BCF = 1.75 (log Kow 6.0 to 8.0)
log BCF = 1.00 (log Kow 8.0 to 9.0)
log BCF = 0.50 (log Kow > 9.0)
- Defined domain of applicability: The BCFBAF method classifies a compound as either ionic or non-ionic. Ionic compounds include charged nitrogen compounds (nitrogen with a +5 valence such as quaternary ammonium compounds).
- Appropriate measures of goodness-of-fit and robustness and predictivity:
- Mechanistic interpretation:

5. APPLICABILITY DOMAIN
Currently there is no universally accepted definition of model domain. However, users may wish to consider the possibility that bioconcentration factor estimates are less accurate for compounds outside the MW and logKow ranges of the training set compounds, and/or that have more instances of a given correction factor than the maximum for all training set compounds. It is also possible that a compound may have a
functional group(s) or other structural features not represented in the training set, and for which no fragment coefficient was developed; and that a compound has none of the fragments in the model’s fragment library. In
the latter case, predictions are based on molecular weight alone. These points should be taken into consideration when interpreting model results.

As quaternary ammonium compounds are represented in the training set and the molecular weight of C12-18 alkyldimethyl ammonium chloride (ranging from 229.45 to 790.54) is within the range covered by the training set (minimum MW: 68.08, maximum MW: 991.80), the substance lies in the applicability domain of the model. Although the longer chain derivatives are outside of the range of log Kow of the training set (minimum LogKow: -6.50, maximum LogKow: 11.26), the major part of the constituents is within the applicability domain.

6. ADEQUACY OF THE RESULT
The results are considered appropriate to support teh read-across approach.
Principles of method if other than guideline:
prediction of bioaccumulation using EpiSuite v4.11, BCFBAF v3.01
GLP compliance:
no
Type:
BCF
Value:
70.79 L/kg
Basis:
whole body w.w.

Summary Results:

 Log BCF (regression-based estimate): 1.85 (BCF = 70.8 L/kg wet-wt)

 Biotransformation Half-Life (days) : 0.277 (normalized to 10 g fish)

 Log BAF (Arnot-Gobas upper trophic): 0.40 (BAF = 2.5 L/kg wet-wt)

 

Log Kow (experimental): not available from database

Log Kow used by BCF estimates: 1.22

 

Equation Used to Make BCF estimate:

  Log BCF = 1.85 (Ionic; 11 or more -CH2- groups)

 

 

  Estimated Log BCF = 1.850 (BCF = 70.79 L/kg wet-wt)

Conclusions:
The BCF of Di-C12-18 alkyldimethyl ammonium chloride was predicted to be 70.79 L/kg (Episuite v4.11, BCFBAF v3.01).

Description of key information

BCF = 13 L/kg (river water); read-across from DODMAC and DTDMAC

Key value for chemical safety assessment

BCF (aquatic species):
13 L/kg ww

Additional information

No experimental data on bioaccumulation are available for Di-C12-18 alkyldimethyl ammonium chloride. Data are, however, available for the closely related source substances DTDMAC and DODMAC. A justification for read-across is attached to IUCLID section 13.

 

Lepomis macrochirus was exposed to 14C-DTDMAC for 49 days in a continuous flow-through system in river water and laboratory water with mean concentrations in the test period of 18 μg/L and 16 μg/L respectively (no solvent carrier, Lewis & Wee, 1983). The river water was sampled at Town River, Massachusetts, and contained 2-84 mg/L suspended solids, 0.04-0.59 mg/L (methylene blue active substances) MBAS and 10-15 mg/l disulfine blue active substances (DBAS) (pH = 6.4-7.7; total hardness = 14-38 mg/L CaCO3). In river water, BCFs of 13 L/kg in the whole body and 94 in the inedible tissue (viscera) were estimated based on measured concentrations. When laboratory water was used, the respective BCFs were 32 and 256 L/kg. In both waters DTDMAC did not concentrate to a significant degree in edible tissue (BCF of the fillets < 5 L/kg). In a depuration phase in well water 93% of the accumulated radioactivity was eliminated from the inedible tissues after 14 days.

Overall, these results demonstrated that testing cationic surfactants under more realistic conditions (in river water) give lower bioavailability compared to studies using laboratory water.

Based on these test data, it can be concluded that DTDMAC does not accumulate in fish.

Juvenile fish (Pimephales promelas) were exposed to DODMAC for 24 h under flow-through conditions, followed by a depuration period of 72 h. Without Humic acid, a BCF of 103.8 L/kg could be calculated based on the uptake rate constant (k1) of 1.35 mg/g x h and the depuration rate constant (k2) of 0.013 mg/g x h. With the addition of 1 mg/L and 6.8 mg/L Humic acid, the BCF was 37.5 and 2.8 L/kg, respectively.

 

Low bioaccumulation potential of Di-C12-18 alkyldimethyl ammonium chloride is also predicted by QSAR. The BCF of Di-C12-18 alkyldimethyl ammonium chloride was predicted to be 70.79 L/kg (Episuite v4.11, BCFBAF v3.01).