Amines, N-(3-aminopropyl)-N-(C16-18 and C18-unsatd. alkyl)trimethylenedi-

Endpoint summary

Additional information

Branched polyamines C16-18 have a limited solubility in water and also have a strong tendency to adsorb to negatively charged surfaces such as suspended matter, algae and test vessels or organic material (including dissolved organic matter such as humic acids). Many cationic substances in general but long chain polyamines in particular rank among the most difficult substances to test in environmental toxicology. Standard guideline studies are inappropriate to test substances with such properties and the current REACH Guidance Documents do not provide sufficient guidance concerning bioavailability and exposure assessment for cationic surface-active substances like the polyamines as these were written with normal hydrophobic chemicals in mind, failing to take into account the lack of bioavailability that occurs in the environment with these substances.

The long-term aquatic ecotoxicity tests with branched polyamines C16-18 were therefore performed in river water to allow a PEC_{aquatic, bulk}/PNEC_{aquatic, bulk}approach and is considered to be conservative but more environmentally realistic than the standard method. This approach is based on PEC estimations representing ‘total aquatic concentrations’. To characterize the risk to the aquatic compartment the PEC_{aquatic, bulk}is compared with the PNEC_{aquatic, bulk}derived from river water ecotoxicity studies (ECETOC, 2001).

In order to classstandardlaboratory toxicity study valid, it is of particular importance that - besides information on test substance, test method /conditions and test organism used - suitable precautions are taken to prevent the loss of test substance by adsorption and that exposure concentrations are based upon measured levels.

For ecotoxicity tests performed using the “bulk”approach, however, adsorption to suspended matter and DOC is acceptable and only adsorption to glassware should be accounted for. For a valid bulk approach test the concentration-effect relationship should be based on the sum of adsorbed and dissolved substance in the volume of the medium tested. One of the advantages of the bulk approach tests with these difficult substances is that in the presence of suspended matter, humic acids and/or algae, the residual sorption to glassware will be negligible. The results of these bulk approach tests are therefore much easier to interpret, more environmental realistic, and if compared to PEC_bulkclearly provide a more appropriate assessment of risks for the environment. All effect values given for tests performed in natural river water are therefore based on the nominal test item concentrations. The PNEC_{aquatic bulk}should calculated using the assessment factor proposed by the TGD.

For the aquatic compartment two chronic key studies are available for the branched triamine C16-18. The chronic algae test gave a ErC10 of 347 mg/L and the chronic daphnia test a NOEC (reproduction) of 0.32 mg/L. Note that both chronic key studies are performed in river water with relatively low (realistic worst-case) DOC and suspended matter concentrations. This means that for the risk assessment the bulk approach should be applied i.e. both the effect and exposure assessment are based on the total concentration (dissolved and sorbed).

For the toxicity to micro-organisms an EC50 and EC10 of respectively 86 and 17 mg/L was observed for activated sludge bacteria after 3 hour exposure. In the absence of measured data, the toxicity data as observed for the branched triamine C12 (2372-82-9) is used for read-across as a worst-case. For this reason an overview of the aquatic ecotoxicity data of both the branched triamine C12 and C16-18 is presented in the table below.

Table available aquatic ecotoxicity for branched triamines

Branched triamines	CAS number	72 h algae ERC10/ NOEC (µg/L)	72 h algae ERC50(µg/L)	48 h daphnia EC50 (µg/L)	96 h Fish LC50 (µg/L)	21 d daphnia EC50 (µg/L)	21 d daphnia EC10/ NOEC (µg/L)
N-(3-aminopropyl)-N-dodecylpropane-1,3 diamine	2372-82-9	9.5	15	78	431	50	24
N-(3-aminopropyl)-N-N-(C16-18 evennumbered, 18 unsaturated)-alkylpropane-1,3-diamine	1219826-66-0	347	914			566	320

Figures for branched triamine C12 (CAS no 2372-82-9) are obtained by performing ecotoxicity tests in reconstituted lab water.

From the branched triamine C12 figures it is clear that fish are clearly less sensitive compared to algae and daphnia. In addition it is clear that the long-term EC50 can be used as a worst-case short-term EC50 for daphnia. No short-term fish data are available for branched triamine C16 -18 but as fish data for the branched triamine C12 will be used as a worst-case.

Based on the observed lower toxicity to fish not only for the branched polyamines C12 but also for primary fatty amines and mono and dialkyl quats it is considered unlikely that fish toxicity will be critical for Triamine C16 -18. This is supported by the low acute to chronic ratio observed in the long-term daphnia test. The daphnia reproduction test result shows that at 1 mg/L all parental daphnids were immobile within 11 days, with only one daphnia with one brood others did not reproduce, while at the next concentration of 320 µg/L not only is there no immobilisation, but there is no detrimental effect on reproduction when compared to the control. These observations results in the derivation of a NOEC of 320 µg/L resulting in a low acute-to-chronic ratio. A low acute-to-chronic ratio is indicative of a non-specific mode of action and is often associated with not systemic effects. This observation is consistent with the known effects of cationic surfactants on aquatic organisms, where toxicity is associated with physical binding to respiratory membranes. This explains the steep concentration curves seen and the lack of intermediate chronic effects on reproduction.Hence any additional toxicity testing with fish will not add scientific value to the ecotoxicity profile of the Triamine C16-18 other than for obtaining a lower assessment factor. It is therefore concluded that for scientific reasons and in accordance to REACH legislation further testing on fish has to be avoided for reasons of animal welfare and that based on the weight of evidence available on ecotoxicity data for several cationic surfactants a safety factor of 10 may be applied for the derivation of the PNEC_{aquatic, bulk.}