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EC number: 271-689-5 | CAS number: 68604-38-6
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Bioaccumulation: aquatic / sediment
Administrative data
Link to relevant study record(s)
Description of key information
Polyol esters are expected to have a low potential for bioaccumulation.
Key value for chemical safety assessment
Additional information
Experimental data on bioaccumulation of Fatty acids, C16-18 and
C18-unsatd., hexaesters with dipentaerythritol (CAS 68604-38-6) is not
available. The evaluation of the bioaccumulation potential of the
substance is therefore based on a Weight of Evidence (WoE), combining
all available related data. This is 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. 1907/2007 Annex IX and X
(Guidance on information requirements and chemical safety assessment
Chapter R.7c: Endpoint specific guidance, R.7.11.5.3, page 123 ff (ECHA,
2012)).
Environmental behaviour
The bioaccumulation potential of a substance is driven by the
physic-chemical properties of the substance triggering the
bioavailability as well as by metabolism and excretion. The
bioavailability of the substance is expected to be low. Though the
substance has a high calculated partition coefficient (log Kow of main
components: 42.27 - 46.87, KOWWIN v1.68; Blum, 2011) indicating the
potential to bioaccumulate a significant accumulation is not expected
based on the environmental fate and on BCF/BAF calculation.The
calculated log Koc values of the main components of > 5 indicates that
the substance will adsorb to suspended organic particles, dissolved
organic matter and to some degree biota in the aquatic environment
(Jaffé, 1991).A potential uptake of the substance by organisms of the
pelagic zone is expected to occur mainly via food ingestion since the
substance may adsorb to solid particles. Benthic or sediment-dwelling
organisms may take the substance up by ingestion of contaminated
sediment.
Despite that the substance is not readily biodegradable elimination in
sewage treatment plants is expected due to the high adsorption potential
and the very low water solubility. Insoluble substances are largely
removed in the primary settling tank and fat trap during the
clarification and sedimentation process of waste water treatment
(according to the Guidance on information requirements and chemical
safety assessment, Chapter R7.b (ECHA, 2012)). Only small amounts of the
substance may enter the secondary treatment and thus get in contact with
activated sludge. Due to the high log Koc calculated for the substance
components an extensive adsorption to sewage sludge is expected. Thus
the substances is expected to be removed from the water column to a
significant degree (Guidance on information requirements and chemical
safety assessment, Chapter R.7a (ECHA, 2012)). However, when released to
the aquatic environment the concentration in the water phase will be
further reduced by potential of adsorption to solid particles and to
sediment. Thus a significant uptake of the substance by aquatic
organisms through the water phase is not expected.Considering this, one
can assume that the availability of the substance in the aquatic
environment is generally low, which reduces the probability of uptake by
aquatic organisms (e.g., see McKim et al, 1984; Björk, 1995; Haitzer et
al., 1998).
If the substance is taken up by ingestion, absorption ofFatty acids,
C16-18 and C18-unsatd., hexaesters with dipentaerythritolis expected to
be low based on the molecular weight, size and structural complexity of
the substance. These large and complex structures assume a high degree
of conformational flexibility. Dimitrov et al. (2002) revealed a
tendency of decreasing log BCF with an increase in conformational
flexibility of molecules. They suggest that this effect is related to
the enhancement of the entropy factor on membrane permeability of
chemicals. This concludes a high probability that the substance may
encounter the membrane in a conformation which does not enable the
substance to permeate. Furthermore, the main components of the UVCB
substance have high molecular weights of 1684 to 1853 g/mol. Thus, it is
unlikely that they are readily absorbed due to the steric hindrance of
crossing biological membranes. According to the Guidance on information
requirements and chemical safety assessment; Chapter R.11: PBT
Assessment (ECHA, 2012) a molecular weight of > 700 in combination with
a calculated log Kow of > 8 can be used as enough evidence to conclude
that a substance is unlikely to bioaccumulate. Following 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), the substance is considered to be
poorly absorbed after oral uptake (also see Hsieh & Perkins, 1976).
Metabolism
Esters of fatty acids are hydrolysed to the corresponding alcohol
and fatty acids by esterases (Fukami & Yokoi, 2012). Depending on the
route of exposure, esterase-catalysed hydrolysis takes place at
different places in the organism: after oral ingestion, esters of
alcohols and fatty acids undergo enzymatic hydrolysis already in the
gastro-intestinal fluids. However, it is not anticipated that enzymatic
hydrolysis of the parent substance is taking place in the
gastrointestinal tract due to the high molecular weight and the complex
structure of the molecule. Additionally, the hydrolysis of esterified
alcohol with more than 3 ester groups is assumed to be slow (Mattson &
Volpenheim, 1972). In in vivo studies in rats, a decrease in absorption
was observed with increasing esterification. For example,
pentaerythritol tetraoleate ester had an absorption rate of 64% and 90%
(25% and 10% of dietary fat), whereas the hexaester of sorbitol was not
absorbed (Mattson & Nolen, 1972). As Fatty acids, C16-18 and
C18-unsatd., hexaesters with dipentaerythritol is a hexaester as well,
the absorption rate is expected to be low. In contrast, substances which
are absorbed through the pulmonary alveolar membrane or through the skin
enter the systemic circulation directly before entering the liver where
hydrolysis will basically take place.
Fatty acids, C16-18 and C18-unsatd., hexaesters with dipentaerythritol
are slowly hydrolysed to the corresponding alcohol (dipentaerythritol)
and fatty acids by esterases. It was shown in-vitro that the hydrolysis
rate for another polyol ester (pentaerythritol tetraoleate) was lower
when compared with the hydrolysis rate of the triglyceride glycerol
trioleate (Mattson & Volpenhein, 1972). Thus it is assumed that the
hydrolysis rate for Fatty acids, C16-18 and C18-unsatd., hexaesters with
dipentaerythritol is ever lower in comparison with pentaerythritol
esters.
Therefore, ester bond hydrolysis is expected to occur to a minor extent
in the gastrointestinal tract. Nevertheless possible cleavage products
should be discussed here.
The first cleavage products, fatty acids are stepwise degraded by
beta-oxidation based on enzymatic removal of C2 units in the matrix of
the mitochondria in most vertebrate tissues. The C2 units are cleaved as
acyl-CoA, the entry molecule for the citric acid cycle. For the complete
catabolism of unsaturated fatty acids such as oleic acid, an additional
isomerization reaction step is required. The omega- and alpha-oxidation,
alternative pathways for oxidation, can be found in the liver and the
brain, respectively (CIR, 1987).
The second cleavage product dipentaerythritol can either remain
unchanged or may further be metabolized or conjugated (e.g.
glucuronides, sulfates, etc.) to polar products that are excreted in the
urine.
Overall, the part ofFatty acids, C16-18 and C18-unsatd., hexaesters with
dipentaerythritolthat have become systemically available, might be
hydrolysed and the cleavage products can be further metabolized.
However, due to its high molecular weight, absorption ofFatty acids,
C16-18 and C18-unsatd., hexaesters with dipentaerythritolis not likely
and thus, no extensive metabolism is expected but rather direct
elimination.
Data from QSAR calculation
The interaction between lipophilicity, bioavailability and membrane permeability is considered to be the main reasons why the relationship between the bioaccumulation potential of a substance and its hydrophobicity is commonly found to be described by a relatively 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 the major components of the UVCB substance, are considered to have a low bioaccumulation potential (e.g., Nendza & Müller, 2007; 2010). Furthermore, for those substances with a log Kow value > 10 it is unlikely that they reach the pass level of being bioaccumulative according to OECD criteria for the PBT assessment (BCF > 2000; ECHA, 2012). This assumption is supported by QSAR calculations using BCFBAF v3.01.BCF/BAF values calculated for the single components of the substance exhibit a low bioaccumulation potential (Blum, 2011). A calculated BCF/BAF of 0.89 L/kg (SRC BCFBAF v3.01 Arnot Gobas, upper trophic level) indicates that the substance has a low bioaccumulation potential.Even though the main components of the substance are outside the applicability domain of the model it might be used as supporting indication that the potential of bioaccumulation is low. The model training set is only consisting of substances with log Kow values of 0.31 - 8.70. But it supports the tendency that substances with high log Kow values (> 10) have a lower potential for bioconcentration as summarized in the ECHA Guidance R.11 (ECHA, 2012) and they are not expected to meet the B/vB criterion, which is also in accordance with Annex IX of Regulation (EC) No 1907/2006.
Conclusion
The bioaccumulation potential of Fatty acids, C16-18 and
C18-unsatd., hexaesters with dipentaerythritol (CAS 68604-38-6) is
expected to be low. The substance is characterised by a low water
solubility and high log Koc leading to a low bioavailability. Due to its
high molecular weight, no extensive metabolism of the substance is
expected but rather direct elimination. In conclusion, a bioaccumulation
or biomagnification through the food chain of the substance is not
expected.
It can hence be concluded that the high log Kow, which indicates a
potential for bioaccumulation, overestimates the bioaccumulation
potential of the substance.
A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within CSR.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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