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Ecotoxicological information

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

DTPMP 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 HEDP, 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 DTPMP 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. DTPMP 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 DTPMP 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 be read-across from the analogous substance ATMP sodium salt, a neutralised form of ATMP, and read-across to the DTPMP 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. The study is proposed with ATMP instead of DTPMP because:

    o  ATMP adsorbs slightly more strongly to soil, the soil-water adsorption coefficient (Ksoil-water) is slightly higher for ATMP (~900 m3/m3) than DTPMP (570 m3/m3). This means that in the test there would be a slightly higher fraction in the solid phase than the pore water for ATMP than DTPMP, and

    o  ATMP has a higher purity profile.

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