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Long-term toxicity to aquatic invertebrates

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Description of key information

NOEC (21d) = 3.99 mg/L for Daphnia magna (OECD 211); read-across

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
3.99 mg/L

Additional information

There are no data available on long-term toxicity of 2-amino-1,3-propanediol (APD) to aquatic invertebrates. However, there are reliable data for another member of the chemical category APD belongs to. Therefore, read-across was performed based on a category approach. Within this chemical category, the members are APD, 2-amino-2-methyl-1,3-propanediol (AMPD) and 2-amino-2-ethyl-1,3-propanediol (AEPD), collectively called aminopropanediols. All the members contain a propane backbone carrying the same functional groups, one primary amine group and two hydroxyl groups, at the same position. The three category members differ only in the length of the alkyl side chain, which contains 0, 1 or 2 carbon atoms for APD, AMPD and AEPD, respectively.

Structural similarities of all category members, as well as similarities of short term toxicity results for all three taxonomic groups justify the read across from AEPD to APD in the case of long term toxicity to daphnia.

Both APD and AEPD are well soluble in water (> 900 g/L) and have a very low vapour pressure (0.01 Pa). The relatively low partition coefficient (log Kow) of -1.82 (APD) and -1.02 (AEPD) result in a low potential to accumulate in biological systems. Also the log Koc is low for both substances, 2.96 and 2.31 for AEPD and APD respectively. Acute aquatic toxicity of > 100 mg/L indicates that both substances have low toxic potential to aquatic organisms. By calculating potential metabolites via OECD QSAR toolbox v.2.0 (2010), no relevant metabolites were predicted by the liver metabolism simulator, by the skin metabolism simulator, or by the microbial metabolism simulator. The Cramer classification (related mainly to oral route) also indicates that no metabolism by cytochrome P450 enzymes in vivo is expected for APD and AEPD.

Both OASIS and ECOSAR classification models indicate narcosis as mode of action for all category members, however it is known that for amines the toxicity can be enhanced with respect to baseline and the mode of action can be classified as “amine narcosis”. Nevertheless, as in the general case of narcosis (i.e. with absence of specific and reactive effects – which is confirmed by the presence of only amine and alcohol functional groups), log Kow is the main toxicity trigger, which is very low for both substances.

In the ready biodegradation test (301F), APD reached 100% degradation within 5 days. AEPD is not readily biodegradable, but was rapidly degraded in the inherent test (> 90% with 7 days) and thereby represents the worst case for long-term effects, in comparison to APD.

The study with AEPD was conducted according the OECD guideline 211 and GLP (MOE, 2004). The test organism Daphnia magna was exposed to AEPD in a semi-static system for 21 days, at the test concentrations 3.99, 8.61, 18.7, 41.1, 88.5 mg/L (TWA). A NOEC based on reproduction of 3.99 mg/L was obtained.