Hexamethylenediamine

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.42 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.32 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.04 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

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:

65.35 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

6.54 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 is 0.42 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 acute tests compared to other taxa. Due to the short carbon chain lengths of HMD the submission substance does not show surface active properties and the octanol-water partition coefficient is very low. 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), HMD binds to soil and sediment. In spite of this adsorptive behaviour, HMD was shown to be readily biodegradable fulfilling the 10-day window requirement with total nitrification within 28 days. 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 very low. Due to the observed rapid mineralization, accumulation in soil or sediment is not anticipated. This is confirmed by the recently performed study on nitrogen-transformation by soil organisms (OECD 216; RL 1): independently from the submission substance concentration (between 62.5 and 1000 mg/kg soil dry weight), consistently between 50% and 64% of the submission 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 of the submission substance; considering in addition its ready biodegradability allows concluding on rapid mineralization of the submission substance within natural soil. With regard to the terrestrial compartment, reliable long-term results 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 (14.2 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).

With regard to the sediment compartment, PNEC was calculated using the Equilibrium Partitioning Method based on the experimentally determined adsorption data. For sediment a lower adsorption was observed as compared to soil and following ECHA’s criterion of log Koc > 4 it is concluded that HMD is not strongly adsorbing to sediment. Hence, no additional factor is applied for sediment compartments with regard to the RCR based on PNECsediment 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

1     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:

The lowest acute aquatic toxicity of three trophic levels was determined for Daphnia with a geometric mean EC₅₀(48 h) of 31.5 mg/L. Under Regulation (EC) 2008/1272 (CLP), only one acute category is implemented (category 1). This category is assigned to substances presenting L/EC₅₀≤1 mg/L.

Thus,no acute classificationresults from the available acute aquatic ecotoxicity data on HMD.

 

Chronic hazard category:

Using available acute data, decisive for a possible chronic classification is failure or fulfillment of (1) rapid degradability and / or (2) presence or absence of a bioaccumulation potential.

As substitute for an experimentally determined BCF in fish, log K_OWis taken as an indicator of bioaccumulation potential. As log K_OW of the submission substance is clearly below the cut-off value according to CLP of 4.0 (log Kow HMD ≤0.4), the submission substance is regarded as non-bioaccumulative.

Rapid degradability according to CLP is given for substances which were assessed as “readily biodegradable” in screening studies (OECD 301) with a minimum of 60% O₂-depletion of theoretical maximum (for respirometric OECD 301 methods) within 28 days and at the same time fulfillment of the 10-day-window. This is met by the submission substance. The submission substance is therefore considered as rapidly degradable.

No chronic classification results for the submission substance from the available acute data on ecotoxicity, the degradation and bioaccumulation potentials.

 

Chronic data are availablefor algae with an EC₁₀(72 h, growth rate) of 118.0 mg/L and for aquatic invertebrates (Daphnia magna): NOEC (21 d) 4.2 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: HMD is not classified regarding hazards for the aquatic environment according to CLP.

2     Classification according Directive 67/548/EEC (DSD)

The lowest acute aquatic toxicity of three trophic levels was determined for Daphnia with a geometric mean EC₅₀(48 h) of 31.5 mg/L.

The submission substance is considered as rapidly biodegradable and without potential for bioaccumulation (log Kow HMD << 3.0).

Thus, no classification according to Directive 67/548/EEC (DSD) is resulting.