Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

There are no long-term data on the toxicity of HMDTMP to terrestrial (soil-dwelling) organisms. 

HMDTMP and its salts are highly adsorbing to soil and soil mineral substrates. The nature of the adsorption is believed to be primarily due to interaction with inorganic substrate or generalised surface interactions. High adsorption is consistent with similar behaviour seen for the analogues ATMP and DTPMP, and other common complexing agents such as EDTA. By reference to findings with other similar substances, the binding occurs very rapidly and is effectively irreversible. For environmental fate purposes in exposure assessment this is assessed as a removal process.


The available evidence for HMDTMP and its salts in respect of terrestrial hazard has been considered in the context of the 'soil hazard category' defined in ECHA Guidance (on Information requirements and chemical safety assessment) part R.7c. HMDTMP and its salts are considered to be soil Hazard Category 3 due to their high adsorption values and low toxicity to aquatic organisms properties.

According to the soil hazard category 3 approach for screening assessment, the PNECsoil has been calculated from PNECfreshwater on the basis of the equilibrium partitioning method and a confirmatory long term toxicity to terrestrial organisms has been proposed for the HMDTMP category:

  • The risk characterisation ratio (RCR) based on PNECsoil derived from the equilibrium partitioning method is <1.
  • The long term terrestrial toxicity study proposed is the earthworm reproductive toxicity test (OECD TG 222) because the aquatic data indicate that vertebrate and invertebrate studies are relatively comparable, while algal data is not used in the hazard assessment.
  • The study is proposed to conducted with the analogous substance ATMP sodium salt, a neutralised form of ATMP, and read-across to the HMDTMP category members in terms of active acid content. Both substances are aminomethylenephosphonic acids, see Sections 7.0 and 1.4 of the CSR for read-across justifications and category hypothesis.

Additional information

In accordance with Column 2 of REACH Annex IX, there is no need to further investigate the effects of this substance in terrestrial toxicity to invertebrates and higher plants studies because, as indicated in guidance R.7.11.6 (ECHA 2016), the quantitative chemical safety assessment (conducted according to Annex I of REACH) indicates that the Risk Characterisation Ratio is below 1, therefore the risk is already adequately controlled and further testing is not justifiable.

The substance is involatile and highly adsorbing and low toxicity was observed in short-term aquatic tests, and there is no reason to expect effects in the terrestrial compartment that were not expressed in the aquatic compartment.

Based on the short-term aquatic data set, the most sensitive trophic level is invertebrates. The soil hazard category 3 (ECHA 2014, guidance part R7(c) Table R.7.11—2) has been derived for the category. According to the screening assessment for soil hazard category 3 substances, a PNECsoil has been calculated from the aquatic data on the basis of the equilibrium partitioning method and a confirmatory long term toxicity study with terrestrial invertebrates has been proposed for the structural analogue (ATMP category). The PNEC derived by Equilibrium Partitioning has been derived for the purpose of deriving a chemical safety assessment and the risk characterisation ratios are below 1.

Details on how the PNEC and the risk characterisation ratio have been derived can be found in IUCLID Section 6.0 and Chapters 9 and 10 of the Chemical Safety Report, respectively.