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EC number: 639-566-4
CAS number: 165184-98-5
The toxicity of HCA to various aquatic
organisms has been examined.
Acute aquatic data:
For algae, a study was
performed to assess the effect of the test item on the growth of the
green alga Desmodesmus subspicatus following OECD Guideline 201. It
was not possible to maintain the substance in a 72 hour study at the
solubility limit of the substance as hexyl cinnamic aldehyde
photodegraded and hydrolysed under the conditions of the study. No
efects were observed at a test concentration of 0.32 mg/l, the highest
attainable test concentration that could be attained due to abiotic (and
possibly biotic) degradation properties of the test substance. As no
effects were found at the highest concentration attainable, no EC50 or
NOEC can be provided for this endpoint
One valid OECD 202 study on Daphnia magna was
performed according to GLP, using a flow-through method with a solvent.
The study using solvent was considered valid as, further to a recent
solubility study using a slow-stir method in pure water and daphnid
medium, the solubiltiy in water was observed to be much higher than
previously thought, around 1.5 mg/L. The previous lower solubility
results of 0.3 mg/L were found to be caused by loss of the test
substance during centrifugation step.
For fish, no effects were observed up
to the aqueous solubility limit of the substance. Any mortality or
effects observed were therefore due to physical effects due to the
solvent artificially maintaining the test substance in an emulsion that
was stable under the conditions of the study (flow-through conditions)
but not possible to maintain under environmental conditions.
In conclusion, for acute data, one
valid study was performed in which toxicity was observed below the level
of water solubility of the substance (which is approximately 1.5 mg/L in
daphnid medium). The 48 h EC50 for daphnids of hexyl cinnamic aldehyde
was observed to be 0.247 mg/L.
Chronic pelagic data:
A chronic study was performed on
daphnids according to international guidelines but with the use of
solvent. It appears that there were no statistically significant
treatment-related effects on survival, reproduction or growth at
concentrations up to 63 µg a.i./L which is used as the NOEC for this
study. Growth, measured as length and dry weight, and reproduction were
the most sensitive biological endpoints measured in this study. Daphnids
exposed to the test substance at a concentration of 157 µg a.i./L had
statistically significant reductions in growth and reproduction in
comparison to the pooled control. Consequently, the 21-day EC10 value
for adult immobility was 107 µg a.i./L and the 21-day EC10 value for
reproduction was 69 µg a.i./L.
Under normal circumstances a chronic
fish study could also be requested, however for several reasons this
study is considered unjustified. Due to the abiotic degradation
properties and strong potential for adsorption of th etest substance,
the long-term fish study would be technically difficult to perform. As
this substance is expected to adsorb to organic matter and sediment (in
which it mould rapidly degrade) and would therefore not be expected to
be present at concentrations that could cause toxicity in the pelagic
In conclusion, a chronic effect was
observed on Daphnia magna. The assessment factors used for the
determination of the freshwater and marine PNECs is 50. Two long-term
results from species representing two trophic levels: Daphnia and
algae, are available and the lowest NOEC found if for daphnids as no
effects were observed at the highest concentration testable for algae.
Based on biodegradation studies,
micro-organisms are not considered sensitive to the test substance.
Sediment and soil PNECs were
determined using the Partition Equilibrium theory. In an environmental
CSA, neither of these compartments were found to lead to RCRs greater
than 1 for manufacturing, compounding, formulation or use of hexyl
cinnamic aldehyde. For this reason and due to the ready biodegradability
of the substance, it is considered that long term studies on sediment
and soil are not scientifically justified.
Secondary poisoning is not considered
likely for this substance as it does not meet PBT or vPvB criteria and
notably the substance has been shown to degrade extremely rapidly in the
Chronic sediment toxicity
A sediment toxicity study was performed
according to OECD Guideline 225 and in compliance with GLP. Following
the preliminary range-finding tests, groups of oligochaete Lumbriculus
variegatus were exposed to Hexyl Cinnamic Aldehyde in a static
water-sediment system for 28 days by spiking the test item into
artificial sediment with concentrations of 3.2, 10, 32, 100, 320 and
1000 mg/kg sediment dry weight followed by a recovery phase of further
28 days in clean sediment.
The concentrations of Hexyl Cinnamic
Aldehyde in the sediment and the overlying water were analytically
verified for all test item concentrations (Day -7) was 92 % of the
nominal value and were in the range of 26 - 81 % of the nominal values.
On Day 7 decreased to 9 – 52 %. At the end of the exposure period (Day
28) the measured concentrations further decreased to < LOQ in the lowest
2 concentrations, just 2% of the nominal in concentrations from 32 to
320 mg/Kg dw and 13 % of the highest concentration at 1000 mg/Kg dw. In
the aqueous layer the concentrations were constantly <LOQ during the
test. This provides further evidence that the substance would be rapidly
removed in the sediment compartment and unlikely to be transferred to
the pelagic compartment.
After 28 days of exposure, the test item
induced no evident mortality (< 10%) at all concentrations. The total
number of worms was statistically significantly reduced at 100, 320 and
1000 mg/kg sediment dry weight compared to the pooled control. The EC50,
NOEC and LOEC values for the total number of worms were determined to be
334 (253-451), 32 and 100 mg/kg sediment dry weight, respectively. The
biomass EC50, NOEC and LOEC values for worm biomass were determined to
be 659 (397-470), 100 and 320 mg/kg sediment dry weight, respectively.
Effects on the worms themselves were limited
during the study. No significant mortality was observed (>10%) at any
concentration. Moreover, effects observed on biomass and total worm
number were suspected to be due to palatability issues related to the
high concentrations. At the highest concentration of 1000 mg/Kg dw, the
worms refused to burrow and in the recovery study complete reversibility
of the effects were demonstrated.
GHS classification: The test substance is
Aquatic Acute 1 / H400 and
Classification according to the Directive 67/548/EEC:
The test substance is classified as R50/R53 for the environment.
Acute toxicity to aquatic organisms is <1 mg/L. While it appears
that the test substance is readily biodegradable, on the basis of the
available evidence concerning the potential to accumulate (log Kow =
5.3) and observed toxicity in long-term, the test substance may present
a long-term danger to the structure and/or functioning of aquatic
ecosystems. There is no additional scientific evidence to suggest that
the substance or its degradation products will constitute a potential
long-term danger to the aquatic environment.
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.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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