Cyclohex-1,2-ylenediamine

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

1.3 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

1.3 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.13 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

PNEC marine water (intermittent releases):

0.13 mg/L

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

29.1 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

202.3 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

20.2 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:

3.52 mg/kg soil dw

Assessment factor:

50

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

The calculated PNEC aquatic for the submission substance DCH is 1.3 mg/L, using an assessment factor of 10 based on the fact that chronic toxicity results are available for two trophic levels, and combined with the fact that acute toxicity data for fish demonstrated that this trophic level is clearly the least sensitive by far more than a factor of 10 in relation to the ErC50 determined from algae (being representative for acute exposure, as no acute toxicity tests on aquatic invertebrates is available for DCH). Due to the short cyclic carbon chain length of DCH, any surface-active properties can safely be excluded, and the octanol-water partition coefficient is very low (below 1). Because there is no potential for bioaccumulation, secondary poisoning needs not to be assessed. Aliphatic amines are readily protonated at environmental pH and due to their positive charge are prone to bind to negatively charged solid matter. According to the available adsorption-desorption study (OECD 106; RL1) on read across source substance 1,6-hexane diamine (HMD), there is relevant binding to soil and sediment. In spite of this adsorptive behaviour, DCH was shown to be readily biodegradable fulfilling the 10-day window requirement with total nitrification within 28 days (measured nitrate concentration approximately equalled the theoretical one). From these properties, rapid degradation in sewage treatment plants or the environment is expected which would lead to overall low environmental concentrations. In addition, due to adsorption on suspended matter or soil, bioavailable concentrations in the aquatic phase are expected to be low. Due to the observed rapid mineralization, accumulation in soil or sediment is not anticipated. This is confirmed by the study on nitrogen-transformation of read-across source substance HMD by soil organisms (OECD 216; RL 1): independently from the substance concentration (between 62.5 and 1000 mg/kg soil dry weight), consistently between 50% and 64% of the substance borne nitrogen was transformed to nitrate within 28 days, in addition to the nitrate stemming from amending soil with Lucerne meal containing nitrogen. As cleavage of the C-N-bonds is a prerequisite for nitrification and will reduce adsorption and increase bioavailability; and considering in addition ready biodegradability; this allows for concluding on rapid mineralization of DCH within natural soil. Regarding the terrestrial compartment, reliable long-term results from read-across source substance HMD on earthworm (OECD 222; RL 1) and soil microorganisms (OECD 216; RL1) are available. A PNEC_soil was derived from these data in parallel to the EPM-method, as required according to ECHA guidance R.7c, sections R.7.11.5.3 and R.7.11.6.3. From these experimental data (two trophic levels, i.e. detrivors and consumers; AF 50 according to ECHA guidance R.10), a terrestrial PNEC of 3.52 mg/kg soil (dw) results. This value is lower compared to the terrestrial PNEC obtained from EPM (44 mg/kg soil dw after application of additional factor of 10) and is therefore used for environmental risk assessment. As there is no indication of risk from these confirmatory long-term soil toxicity results (PEC/PNEC_exp <1), no further toxicity testing for soil organisms is required (ECHA guidance R.7c).

Regarding the sediment compartment, the PNEC was calculated using the Equilibrium Partitioning Method based on the aquatic PNEC and the experimentally determined adsorption data from read-across source substance HMD. For sediment, a lower adsorption was observed as compared to soil, and following ECHA’s criterion of log Koc > 4 it is concluded that DCH is not strongly adsorbing to sediment. Hence, no additional factor is applied for sediment compartments with regard to the RCR based on PNEC_sediment derived via the equilibrium partition method. As there is no indication of risk from this RCR (PEC/PNEC_EPM <1), no further toxicity testing for sediment organisms is required.

Conclusion on classification

Classification according to Regulation (EC) 2008/1272 (CLP)

Classification according to Regulation (EC) 2008/1272 (CLP) is performed independently for acute and chronic hazards. If data for chronic hazards are incomplete (data not available for all three trophic levels), chronic classification is performed both, based on acute data and environmental fate and based on available chronic data, and the more stringent outcome is taken for final chronic classification.

Acute hazard category:
For the most sensitive trophic level, aquatic invertebrates, no acute data are available for DCH. However, because long-term exposure integrates short term effects, if long-term ECx-values are definitely above the threshold of <= 1 mg/L for classification into aquatic environmental hazard Category Acute 1, there is no need to classify for this hazard class. As the most sensitive trophic level was identified without doubt to be aquatic invertebrates, with representative species Daphnia magna tested in a reproduction test according to OECD TG 211, the determined EC50 (21 d; reprod.) of 32 mg/L definitely excludes the need for acute hazard classification.

Thus, no acute classification results from the available ecotoxicity data on DCH.

Chronic hazard category:
Because of the lack of chronic toxicity data for fish, formally chronic classification based on acute data needs to be considered. However, fish toxicity is such low (LC50 96 h: 1825 mg/L) that any classification needs can readily be excluded, besides the fact that the substance is neither bioaccumulative nor persistent (but readily biodegradable). Accordingly, no chronic classification results for DCH from the available acute data on ecotoxicity.

Chronic data are available for Daphnia and algae, with Daphnia being considerably more sensitive with an EC10 (21 d; reprod.) of 13 mg/L. To trigger a chronic classification, such chronic data have to be inferior or equal to 1 mg/L; which is not the case here. Thus, also based on available chronic data, no chronic classification results.

Final conclusion: DCH is not classified regarding hazards for the aquatic environment according to CLP.