(E)-1-(2,6,6-trimethyl-1,3-cyclohexadien-1-yl)-2-buten-1-one

Ecotoxicological Summary

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:

0.087 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

8.67 µg/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:

0.017 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 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. This study (NOACK, 2015) was performedon the registered substance according to a OECD Guideline 203 in compliance withGLP.In this study, the test substance was exposed to zebra fish Danio rerio at nominal concentrations of 0.342, 0.751, 1.65, 3.64 and 8.00 mg/L, corresponding to geometric mean measured concentrations of 0.263, 0.664, 1.34, 3.47 and 7.30 mg/L, under semi-static conditions for 96 hours, plus one control without test substance. According to the results of this study, the 96h-LC50 was determined at 1.09 mg/L (95% CL: 1.08 -1.10 mg/L), based on geometric mean measured concentrations.

To assess the short-term toxicity to aquatic invertebrate and algae, two reliable QSAR results are available.The QSAR predictions (iSafeRat holistic approach v1.4) has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predict the ecotoxicological values which would be expected when testing the substance under experimental conditions in a laboratory following OECD Guidelines. The ecotoxicological predictions were determined using a validated QSAR for the Mode of Action in question, (MOA 1, non-polar narcosis). Use of this MOA for substitutedα,β-unsaturated ketones has previously been demonstrated as acceptable in a position paper (KREATiS, 2015; available in the Endpoint Study Records). This QSAR is based on validated data for training sets for which the concentrations of the test substance had been determined by chemical analyses over the test period. According to these predictions, the 48h-EC50 value for aquatic invertebrates, based on mobility, was determined to be 9.0 mg/L (95% CL: 8.2 - 9.9 mg/L), and the 72 -h ErC50 value for algae, based on growth rate, was determined to be 8.3 mg/L (95% CL: 7.3 - 9.5 mg/L). The substance falls within the applicability domain of the model.

Finally, to assess the toxicity of the registered substance to microorganisms, one experimental study is available. This study (NOACK, 2015) was performed on the registered substance according to OECD Guideline 209 in compliance with GLP, under static conditions during 3 hours.The mean inhibition of respiration for the test item replicates were -3, 2, 12, 53 and 58% at nominal test substance concentrations of 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.

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 considered readily biodegradable due to the 10-day window not fulfilled, and is considered hydrolytically stable at environmentally relevant pH. However, as 77% biodegradation was observed after 48 days of exposure in the biodegradation study, the substance is not considered persistent. The registered substance is considered environmentally low mobile in soils (according to P.J. McCall et al., 1980) with an estimated Koc value at 759.7 L/kg (log Koc = 2.88) and is not considered bioaccumulable. Indeed, the experimental BCF value is comprised between 14 and 56, 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 = 14 - 56.

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