[nitrilotris(methylene)]trisphosphonic acid, ammonium salt

Short-term toxicity to fish

Description of key information

There are no test data for the substance. A 96 h LC50 value of 160 mg/L (as active acid) has however been determined for the effects of ATMP acid (CAS 6419-19-8) on mortality of the freshwater fish Salmo gairdneri (now known as Onychorhynchus mykiss). A 96 h LC50 value of >282 mg/L (as active acid) has also been determined for the effects of ATMP  on mortality of the marine fish Cyprinodon variegatus. The result was obtained in a test conducted with ATMP 5Na salt (CAS 2235-43-0) and the result has been expressed relative to the concentration of ATMP acid.

Additional information

ATMP-xNH₄ will dissociate when it is released into aqueous environments to yield ATMP and ammonia.

The assessment of short-term toxicity of the substance to fish and the resulting hazard classification are therefore, in the absence of test data for the substance, based on treating the substance as a preparation. Test data do not indicate that ATMP acid is toxic to fish following short-term exposure. The un-ionised ammonia moiety is however known to be toxic to aquatic organisms and concentration limits, as stipulated in the Annex I (DSD)/Annex VI (CLP) entry for ammonia, will be applied in order to derive a hazard classification for ATMP-xNH_4.

ATMP and ammonia will also be treated separately for the purposes of deriving PNECs for the aquatic compartment. A PNEC_aquatic for ammonia has already been derived by the UK Environment Agency for the purpose of setting an Environmental Quality Standard (EQS) under Annex VIII of the Water Framework Directive (WFD). The relevant data are presented in section 7.6 of the CSR. This PNEC is also considered to be adequate for the purpose of risk characterisation of ammonia present in ATMP-xNH₄. A PNEC for ATMP will be determined using test data for the substance.