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EC number: 939-592-9
CAS number: 67254-71-1
The test substance was not stored inside fish and no relationship
between BCF and lipid content was observed. The elimination rate
suggested rapid biotransformation of the test substance.
Alcohol ethoxylates are not expected to bioaccumulate due to a
rapid biotransformation and excretion.
The bioaccumulation potential of alcohol ethoxylates fish (Fathead
minnow) was extensively investigated and in flow-through experiments by
Tolls (1998) and Tolls et al. (2000). The BCFs, reported in the
publication ranged between <5 and 387.5 L/kg. For the uptake rate
constant (k1) a range of 330 - 1660 (L/kg per day) was reported; the
determined elimination rate constant (k2) ranged from 3.3 - 59 L/kg per
day. According to the authors, the uptake rate constant and the BCF
increase with increasing chain length of alkyl chain. Whereas an
increase in the length of the ethoxylate chain reduces the
bioaccumulation potential. The elimination rate constant decreases with
increasing alkyl chain length and decreasing ethoxylate chain length. A
decrease in the elimination rate constant was correlated with increasing
alkyl chain length and decreasing ethoxylate chain length. The results
indicate a rapid biotransformation of alcohol ethoxylates.
In a publication by Dyer et al. (2008) the biotransformation of
two surfactants, i.e. C12-2-LAS and C13EO8, was tested in subcellular
and cellular hepatic systems. Liver homogenates and microsomes from the
common carp (Cyprinus carpio) and rainbow trout (Oncorhynchus
mykiss) were used as subcellular systems. The cellular systems
consisted of primary hepatocytes from the common carp (Cyprinus carpio)
and PLHC-1 cells, and hepatocarcinoma cells from the clearfin livebearer
(Poeciliopsis lucida). All in vitro systems were exposed to
radiolabelled test compounds and assayed for biotransformation using
liquid scintillation and thin layer chromatographic methods. Predicted
BCF-values corresponded closely to measured values in several fish
species, verifying the utility of in vitro systems in refining
Kow-only-based BCFs via the inclusion of biotransformation rates.
Resulting from that study biotransformation of C13EO8 could be
demonstrated with both, primary hepatocytes and PLHC-1 cells, although
with different metabolic profiles. First-order in vitro clearance rates
based on exposure of C13EO8 to rainbow trout and carp microsomes and
primary hepatocytes from carp lead to predicted BCF-values which were
below 98 for all test systems.
Munoz et al. (2010), performed in-vivo experiments investigating
the uptake and elimination kinetics of pure homologues of linear alcohol
ethoxylates. The bioconcentration (BCF), biotransformation
(identification of the metabolites generated by an organism), and
depuration at different exposure levels was determined. Steady state
BCF-values ranged from 99.4 to 130 L/kg/d for the tested alcohol
ethoxylates. For C12EO6 the rate of uptake (k1) ranged from 63.2 to
122.6 L/kg/d. The rate of uptake was not affected by the exposure
concentration. For the rate of elimination (k2) the results showed a
very slight decrease with increasing exposure level. As internal
degradation products in fish, the glucuronic conjugate of alcohol
ethoxylates was detected. The results suggest that predominant
biotransformation process for alcohol ethoxylates is a phase II
biotransformation. Although the depuration percentage was very high at
the beginning of the elimination phase, a slight increase was observed
over time. Alcohol ethoxylates were considered to have a delayed
elimination and potential of short-term bioaccumulation (Beek, 2000).
The common principle of the biotransformation of surfactants is
either an enzymatic cleavage of the two surfactant molecule moieties
(forming a fatty alcohol/acid and a hydrophilic product) or is a
terminal oxidation and subsequent stepwise degradation of the alkyl
chain (leaving again a hydrophilic product). The metabolism of the
surfactant alkyl chain through a combination of omega- and
beta-oxidations with subsequent excretion of a short chain derivative
has been demonstrated for several fish species (Newsome et al., 1995;
Van Egmond et al. 1999).
In conclusion, bioconcentration factors of alcohol ethoxylates in
the aqueous phase are below the level of concern, and can be
quantitatively related to the length of the hydrophobic and hydrophilic
components. There is also evidence that overall molecular size may place
constraints on biological uptake. The cited studies cited indicate no to
long-term retention of accumulated surfactant material in tissue. The
studies provide clear evidence that alcohol ethoxylates are rapidly
eliminated and metabolised. Although the fate of metabolites of AE has
not been thoroughly studied, rapid biodegradation of alcohol ethoxylates
in the aquatic environment is considered to be a mitigating aspect,
since the rate of biodegradation of alcohol ethoxylates are
significantly faster than the uptake rates of bioaccumulation.
Dyer, S. D., Bernhard, M. J., Cowan-Ellsberry, C. C.,
Perdu-Durand, E., Demmerle, S. and Cravedi, J.-P. (2008): In vitro
biotransformation of surfactants in fish. Linear alkylbenzene sulfonate
(C12 -LAS) and alcohol ethoxylate (C13EO8).Chemosphere 72, 850 -862.
Munoz DA, Gomez-Parra A and Gonzalez-Mazo E (2010) Influence of
the molecular structure and exposure concentration on the uptake and
elimination kinetics, bioconcentration, and biotransformation of anionic
and nonionic surfactants, Environ. Toxicol. Chem, 29 (8): 1721-1734
Newsome, C. S., Howes, D., Marshall, S. J. and Van Egmond, R. A.
(1995): Fate of some anionic and alcohol ethoxylate surfactants in
Carassius auratus. Tenside Surfact. Deter. 32, 498 -503.
Van Egmond, R., Hambling, S. and, S. (1999): Bioconcentration,
biotransformation, and chronic toxicity of sodium laurate to zebrafish
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