Registration Dossier

Administrative data

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:
PNEC aqua (freshwater)
PNEC value:
1.09 µg/L
Assessment factor:
1 000
Extrapolation method:
assessment factor
PNEC freshwater (intermittent releases):
10.9 µg/L

Marine water

Hazard assessment conclusion:
PNEC aqua (marine water)
PNEC value:
0.11 µg/L
Assessment factor:
10 000
Extrapolation method:
assessment factor

STP

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

Sediment (freshwater)

Hazard assessment conclusion:
PNEC sediment (freshwater)
PNEC value:
0.107 mg/kg sediment dw
Extrapolation method:
equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:
PNEC sediment (marine water)
PNEC value:
0.011 mg/kg sediment dw
Extrapolation method:
equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:
no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:
PNEC soil
PNEC value:
0.021 mg/kg soil dw
Extrapolation method:
equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
PNEC oral
PNEC value:
6.67 mg/kg food
Assessment factor:
90

Additional information

Aquatic toxicity (including STP)

Experimental studies and/or QSAR results are available to assess the aquatic toxicity of the registered substance.

- To assess the short-term toxicity to fish, one experimental study is available on the registered substance. This study (Kurume, 2004) was assessed as the key study and was performedon the registered substance according to aJapanese Industrial Standard (JIS K 0102 -1998 -71) with GLP statement. In this study, the test substance was exposed toOryzias latipesat the concentrations of 0 (control with dilution water only), 0.889, 1.33, 2.00 and 3.00 mg/L under semi-static conditions for 96 hours. According to the results of this study, the96h-LC50 was determined at 1.09 mg/L (95% CL: 0.889 - 1.33 mg/L), based on nominal concentrations (no analytical monitoring was performed).

- To assess the short-term toxicity to aquatic invertebrate, one experimental study and one QSAR result are available on the registered substance.

The experimental study(NOACK, 2015) was assessed as the key study and was performed on the registered substance according to OECD Guideline 202 with GLP statement. The test substance was exposed toDaphnia magnaat the concentrations of 0 (control with dilution water only), 0.625, 1.25, 2.50, 5.00 and 10.0 mg/L for 48 hours, under semi-static conditions for 48 hours. According to the results of this study, the 48h-EC50 was determined at 2.37 mg/L (95% CL: 1.99 - 2.81 mg/L), based on analytically confirmed nominal concentrations.

The second data (KREATiS, 2015), assessed as a supporting data, is a QSAR. This QSAR prediction (iSafeRat holistic approach v1.4) was performed on the registered substance.The immobility of the daphnids was determined using a validated QSAR for the Mode of Action in question, (MOA 1, non-polar narcosis), using training set of 58 chemicals derived from 48h-EC50 tests on daphnids, for which the concentrations of the test substance had been determined by chemical analyses over the test period.The48h-EC50 value on the registered substance based on mobility was determined to be 5.5 mg/L (95% CL: 5.0 - 6.1 mg/L). This QSAR result supports the experimental key study performed on the same substance with an EC50 value in the same order of magnitude, considering the biological and experimental variabilities (factor 2 - 3). Therefore, this QSAR is considered relevant and sufficient to assess, alone, the toxicity of the registered substance to aquatic algae, without the use of an experimental study.

- To assess the toxicity of the registered substance to aquatic algae, the QSAR model presented above (iSafeRat holistic approach v1.4) was used.The growth inhibition of algae was determined using a validated QSAR for the Mode of Action in question, (MOA 1, non-polar narcosis), using training set of 40 chemicals derived from 72 -hour ErC50 tests on algae, for which the concentrations of the test substance had been determined by chemical analyses over the test period.The 72 -h ErC50 value on the registered substance based on growth rate was determined to be 5.0 mg/L (95% CL: 4.3 - 5.7 mg/L). An in vivo algae study is not considered necessary as this QSAR is considered sufficient to cover this endpoint.

- Finally, to assess the toxicity of the registered substance to microorganisms, one experimental study is available on a source substance, (2E)-1-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)-2-buten-1-one (CAS n° 23726 -93 -4). This substance is structurally similar to the registered (target) substance. Both the target and the source substances are mono-constituents. They are structurally related, with the same 2,6,6-trimethylcyclohexyl ring branched with 2-buten-1-one chain at the C-1 position. They differ by the number and location of the endocyclic double bonds: the target has a single one in cyclohex-2-enyl, while the source substance has two, in 1,3-cyclohexadienyl.

Based on structural similarity, comparing physicochemical properties, environmental fate properties and ecotoxicological profile, both substances are not expected to have significantly difference on the activated sludge respiration inhibition.

This experimental valid study was performed according to OECD Guideline 209 (ASRIT) in compliance with GLP, under static conditions during 3 hours.The mean inhibition of respiration for the test substance replicates were -3, 2, 12, 53 and 58% at 10, 32, 100, 320 and 1000 mg/L, respectively. Therefore, the test substance is not considered toxic up to the concentration of 32 mg/L to activated sludge of a municipal sewage treatment plant (NOEC value). The 3h-EC10 value was determined at 93.9 mg/L (95% CL: 81.5 -108 mg/L)and the 3h-EC50 value was determined at 275 mg/L (95% CL: 214 -339 mg/L) of the test substance.

Based on the considerations above, it can be concluded that the result of the ASRIT study conducted with the source substance is likely to predict the properties of the target substance.

Sediment, terrestrial toxicity and hazard for predators

In the absence of any ecotoxicological data for sediment-dwelling/soil organisms, the PNEC sediment/soil were calculated using the equilibrium partitioning method (EPM). Furthermore, no toxicity studies reporting the secondary poisoning effects on bird were available, therefore the 90-day repeated dose toxicity study performed on a read-across substance was used to derive the PNECoral.

Environmental fate and pathways

The registered substance is not readily biodegradable and is considered hydrolytically stable at environmentally relevant pH. Therefore, the substance is considered persistent. The registered substance is considered environmentally low mobile in soils (according to P.J. McCall et al., 1980) with a Koc value at 941.1 L/kg (log Koc = 2.97) and is not considered bioaccumulable. Indeed, the experimental BCF value is comprised between 8.4 and 20, well lower than the CLP criteria at 500 and the PBT criteria at 2000.

Conclusion on classification

No harmonised classification is available on the registered substance.

1 < lowest E(L)C50 value < 10 mg/L; not readily biodegradable; experimental BCF = 8.4 - 20.

Classification according to the Annex VI of the Regulation (EC) No 1272/2008 (CLP): The registered substance is classified Aquatic Chronic 2 for the environment.