Registration Dossier

Administrative data

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:
PNEC aqua (freshwater)
PNEC value:
0.001 mg/L
Assessment factor:
50
Extrapolation method:
assessment factor
PNEC freshwater (intermittent releases):
0.002 mg/L

Marine water

Hazard assessment conclusion:
PNEC aqua (marine water)
PNEC value:
0 mg/L
Assessment factor:
500
Extrapolation method:
assessment factor

STP

Hazard assessment conclusion:
PNEC STP
PNEC value:
10 mg/L
Assessment factor:
10
Extrapolation method:
assessment factor

Sediment (freshwater)

Hazard assessment conclusion:
PNEC sediment (freshwater)
PNEC value:
3.2 mg/kg sediment dw
Assessment factor:
10
Extrapolation method:
assessment factor

Sediment (marine water)

Hazard assessment conclusion:
PNEC sediment (marine water)
PNEC value:
0.064 mg/kg sediment dw
Assessment factor:
500
Extrapolation method:
assessment factor

Hazard for air

Air

Hazard assessment conclusion:
no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:
PNEC soil
PNEC value:
0.398 mg/kg soil dw
Assessment factor:
1
Extrapolation method:
equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
PNEC oral
PNEC value:
6.6 mg/kg food
Assessment factor:
300

Additional information

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 compartment.

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 aquatic environment.

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.

Conclusion on classification

GHS classification: The test substance is classified as:

Aquatic Acute 1 / H400 and

Chronic 2 / H411.

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.