Didecyldimethylammonium chloride

Toxicity to birds

Administrative data

Endpoint:

long-term toxicity to birds

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

bioaccumulation in aquatic species: fish

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance has a low potential for bioaccumulation based on log Kow <=3

Validity criteria fulfilled:

not applicable

Conclusions:

The test substance has low bioaccumulation potential (BCF = 2.1).

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Based on the study results, the test substance is considered to be readily biodegradable.

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

The ready biodegradability of the test substance was determined according to OECD Guideline 301 D (Closed Bottle test) and 301 B (Sturm test) in compliance with GLP. In both studies, the substance was found to be readily biodegradable (Van Ginkel and Pomper, 1996 and Fiebig, 2000). Another study was conducted to determine inherent biodegradability in a Zahn Wellens test (EU Method C.9). The substance required over 15 days of adaptation time, after which degradation was rapid (80% after 28 days). At test start, only adsorption to sludge occurred (Voelkskow, 1989).

Biodegradation mechanism

The pathway of dialkyldimethylammonium salts has been studied with pure cultures. The pure culture, strain DD1, capable of growing on didecyldimethylammonium salt as sole carbon and energy source was isolated from activated sludge. Decyldimethylamine, decanoate, and acetate also served as growth substrates. Dimethylamine was stoichiometrically accumulated during growth on didecyldimethylammonium chloride. These results strongly indicate that the alkyl chains are metabolized sequentially (van Ginkel et al, 2003). Another bacterium is required to degrade the dimethylamine formed (Large, 1971). Nishihara et al (2000) isolated aPseudomonas fluorescensstrain TN4 with didecyldimethylammonium chloride as carbon and energy source. Decyldimethylamine and dimethylamine were identified as intermediates in the biodegradation pathway. Both pure culture studies demonstrate that the degradation of the alkyl chains of dialkyldimethylammonium salts precedes the breakdown of the dimethylamine (Figure). Pseudomonas fluorescensstrain TN4 also degraded other quaternary ammonium salts i.e., alkyltrimethylammonium salts and alkylbenzyldimethylammonium compounds (Nishihara et al, 2000). Strain DD1 was also capable of growing on didodecyldimethylammonium and tetradecyldimethylammonium salts showing broad substrate specificity towards the alkyl chain lengths (van Ginkel et al, 2003). Broad substrate specificities with respect to alkyl chain were demonstrated more comprehensively for other fatty amine derivatives (van Ginkel, 2007[SM1] ).

The Figure 1 in the CSR shows the ability of microorganisms to catalyze C-alkyl-N fissions, thereby forming alkanals that can enter the common pathways of metabolism via β-oxidation (van Ginkel, 2004).

 

Overall, based on the available information, DDAC is considered to be completely mineralised and therefore does notpersist or present a risk to the environment.   

Cross-reference 3

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Based on the study results, the test substance is expected to have little or no potential for mobility in soil. 

Koc at 20 °C:

562 314

A study was conducted to determine the adsorption / desorption of the test substance, DDAC (40.37% active) using the batch equilibrium, according to OECD Guideline 106, in compliance with GLP. 

The amount adsorbed on soils was calculated from depletion of the test substance in the overlaying solution (indirect method). The soils used were EURO-soil standard numbers 1, 2, 3, 4 and 5. The soil/solution ratio was 1:50 (1.0 g soil and 50 mL solution). Based on the results of preliminary tests, 100, 500, 1000, 5000 and 10000 mg/L were selected as nominal concentrations. The concentration of test substance in solution was determined via spectrophotometry. The concentration adsorbed to the soil was then determined by calculation. Under the study conditions, the test substance can be considered as immobile in five soil types. The adsorption mobility (Kaoc) and desorption mobility (Kdoc) coefficients were in the range 40339 to 280547 L/kg and 53883 to 232426 L/kg respectively. Based on the Kd values and organic carbon percentage, the respective Koc values were determined as follows:  

 

Soil type	% Organic carbon	CEC (mval/100g)	Adsorption			Desorption
			Ka	1/na	KaOC	Kd	1/nd	KdOC	Ka/Kd
Euro soil 1: clay	3.29	32.4	9230	0.4447	280547	3718	0.8048	113009	2.48
Euro soil 2: silt loam	28.9	28.9	2868	0.5715	120000	4237	0.7288	177280	0.68
Euro soil 3: loam	16.6	16.6	1456	0.4739	43855	2117	0.6390	63765	0.69
Euro soil 4: silt	17.3	17.3	2188	0.6248	160882	3161	0.6386	232426	0.69
5: loamy sand	24.1	24.1	1787	0.4582	40339	2387	0.5815	53883	0.75

Kaoc = Adsorption coefficient; Kaoc = Adsorption coefficient based on organic carbon content; Kd=Desorption coefficient; Kdoc = Desorption coefficient based on organic carbon content; Ka/Kd = Adsorption / Desorption distribution coefficient 

The 1/n values indicate that a non-linear relationship exists between the concentrations in soil and the concentrations the water. DDAC adsorbs strongly onto soil and does not desorb very easily for all soil types (2-3%). It is well known that, because of their positive charge, cationic surfactants adsorb strongly to the negatively charged surfaces of sludge, soil and sediments. Based on these results, it can be concluded that the substance is immobile in soil (Geffke, 2002). The average Koc was determined to be 129125 L/kg. 

Further, the DDAC biocides assessment report for Product Type 8 conducted under Directive 98/8/EC (evaluating Competent Authority: Italy, June 2015, attached in Section 13 of the IUCLID dataset), presented an additional study on DDAC, apart from the above EQC study (Geffke, 2002). In this study, DDAC was found to be immobile in in four soil/sediment types with the adsorption (Ka) and mobility (Kaoc) coefficients of Ka=1.095 and Kaoc=437805 for sand, Ka=8179 and Kaoc=908757 for sandy loam, Ka=32.791 and Kaoc=1599564 for silty clay loam, and Ka=30851 and Kaoc=1469081 for silt loam. The desorption (Kd) and mobility (Kdoc) coefficients are following reported: Kd=591 and Kdoc=236473 for sand, Kd=2074 and Kdoc=230498 for sandy loam, Kd=8309 and Kdoc=405328 for silty clay loam, and Kd=7714 and Kdoc=367334 for silt loam. The average Koc is 1103801 L/kg.   

The RMS further stated that:“Based on the conclusion of the Ad-hoc follow up on ATMAC/TMAC (PT 8) (opinion of the ENV WG on the Koc to be used for the risk assessment) the koc value to be used for risk assessment is the mean Koc from the both studies available. The Koc value is 562314 L/Kg.” 

 

In general, for quaternary ammonium compounds there is no relationship between the values of Kd and the OC-content of the soils. This confirms that organic carbon content alone is not a suitable normalization basis for charged organic substances (Droge & Goss 2013). When comparing the sorption data per soil, no consistent variation of the Kd–values with the different soils can be discerned. Nevertheless, in line with the biocides assessment report, the higher mean Koc value of 562314 L/kg, which was derived based on both the available studies on DDAC for all soil types, has been considered further for hazard/risk assessment as a worst case.   

Cross-reference 4

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

medium hazard (no threshold derived)

Hazard assessment conclusion:

medium hazard (no threshold derived)

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

medium hazard (no threshold derived)

Hazard assessment conclusion:

medium hazard (no threshold derived)

Hazard assessment conclusion:

medium hazard (no threshold derived)

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified

Hazard assessment conclusion:

no hazard identified