Reaction mass of Phenol, dodecyl-, sulfurized, calcium salts and benzene and butene and calcium carbonate and calcium dihydroxide and sulphur trioxide

Bioaccumulation: aquatic / sediment

Description of key information

A low bioaccumulation potential can be expected for this substance.

Key value for chemical safety assessment

BCF (aquatic species):

71 L/kg ww

Additional information

No experimental data evaluating the bioaccumulation potential of EC 903-161-3 is available. However, the existing data as described below, provide enough evidence (in accordance to the REACh Regulation (EC) No 1907/2006, Annex XI General rules for adaptation of the standard testing regime set out in Annexes VII to X, 1.2, to cover the data requirements of Regulation (EC) No. 1907/2006, Annex IX) to state that this substance is likely to show low bioaccumulation potential.

Intrinsic properties and behavior in the environment

The constituents of EC 903-161-3 exhibit very high log Kow´s (log Kow > 10) and a water solubility < 0.5 mg/L. If insoluble chemicals such as EC 903-161-3 enter a standard STP, they will be extensively removed in the primary settling tank and fat trap and thus, only limited amounts will get in contact with activated sludge organisms (Guidance on information requirements and chemical safety assessment, Chapter R.7b, ECHA, 2012b). Nevertheless, once this contact takes place, these substances are expected to be removed from the water column to a significant degree by adsorption to sewage sludge (Guidance on information requirements and chemical safety assessment, Chapter R.7a, ECHA, 2012a). Therefore, discharged concentrations of these substances into the aqueous compartment are likely to be very low. Should however, such substances to be released into the water phase, based on their hydrophobicity, they will tend to bind to sediment and other particulate organic matter, and therefore, the actual dissolved fraction available to fish via water will be significantly reduced.

Low potential for bioaccumulation

This interaction between bioavailability, hydrophobicity and membrane permeability is regarded as the main reason why the relationship between the bioaccumulation potential of a substance and its hydrophobicity is commonly found to be described by a steep Gaussian curve with the bioaccumulation peak approximately at log Kow of 6-7 (e.g. see Dimitrov et al., 2002; Nendza & Müller, 2007; Arno and Gobas 2003). Substances with log Kow values above 10, which have been calculated for even the smallest structures of the main components of this substance, are, thus, again considered to have a low bioaccumulation potential (e.g. see Nendza & Müller, 2007; 2010). Furthermore, a log Kow value >10 is recognized by the relevant authorities as an indicator for reduced bioaccumulation (Guidance on information requirements and chemical safety assessment, Chapter R.7c, ECHA, 2012c). In fact, the aquatic BCF of a substance is probably lower than 2000 L/kg if the calculated log Kow is higher than 10 (Guidance on information requirements and chemical safety assessment, Chapter R.11, ECHA, 2012d). Regarding this substance, this assumption is supported by QSAR calculations using BCFBAF v3.01 performed for the lowest molecular weight compounds representing the main structures (Gerloff-Elias, 2013, only components > 10% were considered). BCF values were calculated to be between 71 and 3.16 L/kg (regression based method). A model, which considered biotransformation, calculated even lower BCF and BAF values, i.e. < 1 and < 1 - 7 L/kg, respectively (Arnot-Gobas, upper trophic). Even though even the smallest representative structures are, due to their high calculated log Kow values (log Kow >10), outside the applicability domain of the used model (model training set is constituted of substances with log Kow values in the range of 0.31 to 8.70), it can be safely assumed that the calculations reflect a lack of bioaccumulation potential of EC 903-161-3, adequately, since two independent models were used.

Considering the physico-chemical properties and the behaviour in the environment, the relevant route of uptake of this substance in organisms is considered to be predominately by ingestion of particles. As the substance consists of main components featuring high molecular weights, they may not be readily taken up due to the steric hindrance of crossing biological membranes. This assumption is supported by the ‘rule of 5’ (Lipinski et al., 2001), developed to identify drug candidates with poor oral absorption based on criteria in partitioning (log Kow > 5), molecular weight (> 500 g/mole) and hydrogen bonding (more than 5 hydrogen bond donors; more than 10 hydrogen bond acceptors). Considering this, it can be safely assumed that this substance is poorly absorbed after oral uptake. This is supported by existing data for EC 903-161-3, indicating that the substance does not significantly metabolise within the body (please see toxicokinetic statement chapter 7.1 of IUCLID).

Absence of aquatic toxicity

The available data on aquatic ecotoxicity show that EC 903-161-3 is not toxic to aquatic organisms, including fish, algae and invertebrates in short term tests. In addition, the substance was found not to inhibit microorganisms, based on the high biodegradation as observed in the toxicity control of an OECD 301B test and based on a test with activated sludge according to OECD 209. Therefore, adverse effects of EC 903-161-3 to the environment are not anticipated.

Testing difficulties

According to Annex XI, 2 of regulation Regulation (EC) No. 1907/2006 a study does not have to be conducted, if testing is technically not possible. Due to the very low water solubility and high log Kow no reliable test results can be retrieved for the analysis of the substance in the aqueous phase if an aqueous bioaccumulation test (OECD 305) would be conducted. According to “Guidance on information requirements and chemical safety assessment; Chapter R.7c” (ECHA, 2012c), a dietary accumulation test with fish may be used in cases where an aquatic bioaccumulation study is not suitable. However, considering the complexity of this UVCB substance, a reliable chemical analysis (e.g. radioactive labeling) would be almost impossible and a dietary study is thus not a reliable approach to characterising this property. The most reliable approach is therefore one of estimation and so a test would be unjustified and contrary to animal welfare.

Conclusion

EC 903-161-3 is not expected to be bioaccumulative. The high adsorption properties of this substance in combination with the low water solubility will result in very low concentrations in the aquatic environment. Due to the high molecular weight range of the main components and the high octanol/water partition coefficient of > 10 the material is expected to be mainly available to organisms via ingestion of food or suspended organic matter. Absorption from the gut or across other membranes is likely to be very limited. Calculated BCF/BAF values for representative structures of this UVCB, also indicate a negligible potential for bioaccumulation with values well below the trigger value for bioaccumulative substances (< 2000 L/kg).