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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Bioaccumulation testing in aquatic species is waived, in accordance with Regulation (EC) No.1907/2006, Column 2 of Annex IX.  Direct and indirect exposure of the aquatic compartment to the substance is unlikely; the substance has been shown to partition strongly to sediment and activated sludge soils (the key value for adsorption coefficient is Koc = 60,000); and the substance has been shown to be rapidly biodegradable in a soil aerobic degradation study (70.7% mineralization in 28 days).  

Key value for chemical safety assessment

Additional information

According to Regulation (EC) No.1907/2006, Annex IX, Column 2, bioaccumulation testing in aquatic species need not be conducted if the substance has a low potential for bioaccumulation (i.e., log Kow < 3), or if direct and indirect exposure of the aquatic compartment is unlikely.  

The substance has a low potential for bioaccumulation; the predicted octanol-water partition coefficient (Kow) is log Kow = 1.71, which is below the threshold of concern for potential bioaccumulation (i.e., log Kow ≥ 3). However, since the substance is a chloride salt of a quaternary ammonium compound, ionizes in the aquatic milieu, and exhibits surface-active properties, the partition coefficient may not be a reliable indicator of the actual potential for bioaccumulation.

Direct and indirect exposure of the aquatic compartment to the substance is unlikely. The substance has been shown to partition strongly to soils in a study of adsorption on five soils. The values for adsorption coefficient (Koc) ranged from 60,000 L/kg in sand to > 832,000 L/kg in clay/clayey loam; the key value was 60,000 L/kg.  Additionally, the substance has been shown to adsorb strongly to activated sludge solids.  From the activated sludge isotherm study, the value for soil (solids)/water partition coefficient (Kd) was 1150 L/kg, or log Kd = 3.06 (based on the linear regression of the six test concentrations), which indicated that the substance sorbs readily to sludge solids and would, therefore, be efficiently removed from a biological waste water treatment system by clarification. This finding regarding the strong sorption of the substance to sludge solids was supported by another study, which measured substance concentrations in the aqueous phase of a simulated activated sludge unit; this study showed that the substance was removed almost completely from the test system by adsorption to laboratory equipment and sludge. 

The substance has been shown to be rapidly biodegradable in a soil aerobic degradation study; the level of mineralization in soil (70.7% in 28 days) is sufficient documentation for showing rapid degradation in surface water and sediment, in accordance with ECHA guidance (Guidance on the application of the CLP criteria, Version 3.0, November 2012, Section II.2.3.6, p. 498). Substances that degrade rapidly in the environment “are likely to be rapidly metabolized in organisms” (ECHA, Guidance on information requirements and chemical safety assessment, Chapter R.7C, Endpoint-specific guidance, Section R.7.10.3.4, p. 26, November 2012).

Therefore, direct and indirect exposure of the aquatic compartment to the substance is unlikely, and bioaccumulation testing in fish (a vertebrate animal) is not indicated.