diethyl 1,4-cyclohexanedicarboxylate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

7.1 µg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

71 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.71 µg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

PNEC marine water (intermittent releases):

7.1 µg/L

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

32 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.148 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.015 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:

0.025 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

111 mg/kg food

Assessment factor:

90

Additional information

Environmental fate and pathways:

The registered substance is readily biodegradable (69% biodegradation after 28 days, 10 day window fulfilled) and was found to undergo hydrolysis at pH 9 only, with half-life at 25°C of 228 hours. In conclusion, the substance is not considered Persistent. In addition, a low potential for bioaccumulation is expected as the log Kow value of the registered substance is lower than 3.0 (=2.61).

Aquatic toxicity:

Experimental studies (Klimisch score 1), based on international guidelines, are available to assess the acute toxicity of the registered substance on the three aquatic trophic levels: Algae, Aquatic Invertebrates and Fish; and on Microorganisms. In accordance with column 2 of REACH annex IX, further testing on the long-term effects on aquatic organisms does not need to be conducted as the chemical safety assessment does not indicate a need for further investigation.

Among data available, a toxic effect was found at the three trophic levels. The fish, Oncorhynchus mykiss, is the most sensitive species with a 96h-LC50 at 7.1 mg/L. For the aquatic invertebrates Daphnia magna, the 48h-EC50 was determined at 45 mg/L. For the algae Scenedesmus subspicatus, the 72h-ErC50 and 72h-NOEC values based on growth rate were determined at 86 and 25 mg/L, respectively. Finally, for the activated sewage sludge microorganisms, the 3h-EC50 and 3h-NOEC values were determined at 840 and 320 mg/L, respectively.

Terrestrial toxicity:

In accordance with column 2 of REACH Annex IX, terrestrial toxicity studies does not need to be conducted as the registered substance is not supposed to be directly applied to soil and an indirect exposure to soil via sewage sludge transfer is unlikely since the substance is readily biodegradable. Indeed, the substance will be biodegraded within the STP process and as a consequence a transfer to the soil compartment is not expected. In addition, with a log Kow value lower than 3.0, a significant distribution into the soil compartment and a significant exposure of terrestrial organisms is not expected. Finally, based on a conservative estimation from Chesar, the chemical safety assessment of the substance indicates no need to investigate terrestrial testing. Hence, information about effects on terrestrial organisms is not required and the Equilibrium Partitioning Method (EPM) has been used for assessing the hazard to terrestrial organisms.

Conclusion on classification

For environmental hazards, the substance is currently classified as Aquatic Chronic 2 according to the Annex VI of the Regulation (EC) No 1272/2008.

Previously, acute toxicity data were available for all three aquatic trophic levels. The lowest acute L(E)C50 value was in the range 1-10 mg/L (LC50 (fish,Oncorhynchus mykiss) = 7.1 mg/L). Regarding chronic toxicity data, adequate long-term data were not available. The algae NOEC value was only available but even if the algae growth inhibition test is a multi-generation test, this NOEC cannot be used as a chronic data if it’s not supported by long-term data of species of other trophic levels. The substance was considered as non-readily biodegradable based on an experimental study (34% biodegradation after 28 days of incubation), and with an experimental log Kow value measured between 3.04 and 3.19. According to these values, the bioconcentration factor (BCF) was estimated to be comprised between 47.1 and 59.1 L/Kg (BCFBAF model, using log Kow methodology). Based on the poor biodegradation potential, the log Kow greater than 3.0 and the absence of experimental BCF value, the substance was classified for the environment as N, R51/53, according to the criteria of the previous Directive 67/548/EEC (DSD: Dangerous Substances Directive), corresponding to Aquatic Chronic category 2 from the CLP conversion table. Despite log Kow cut-off is now >4 (necessary but not sufficient condition), this classification was consistent with the dataset, based on acute toxicity range (1-10 mg/L) and not rapidly degradable criteria fulfilled. This is the current entry in Annex VI of CLP.

The existing harmonized classification and labeling for this substance is incorrect on the basis of the new valid studies: biodegradation and log Kow studies. The new biodegradation data (Firmenich, 2005) clearly shows that this substance is readily biodegradable (69% biodegradation after 28 days of incubation and satisfied the 10 -day window validation criterion) and the low potential for long-term effects is supported by the new log Kow data (Firmenich, 2010) showing that the log Kow value is lower than 3.0 (relevant for the previous DSD classification only, as in all cases, both log Kow results are lower than 4.0, relevant for the current CLP classification). Therefore, the substance does not meet neither the current nor the previously more stringent criteria for classification for the environment and, as such, the current harmonized classification is no longer justified. Action is therefore required to amend the existing entry in Annex VI of CLP. 

A new CLH proposal was prepared by Firmenich UK Ltd and submitted by the UK Competent Authority in accordance with Article 37(6) of CLP.