Registration Dossier

Diss Factsheets

Ecotoxicological information

Endpoint summary

Currently viewing:

Administrative data

Description of key information

Effects seen in the reliable aquatic (marine) invertebrate test conducted with HEBMP are slightly more severe than for most analogous aminomethylene phosphonates. A reliable existing short-term fish study confirms that fish were less sensitive than invertebrates. Algae are the most sensitive trophic level in both short- and long-term tests.

Fish: 96-hour LC50 >300 mg/l - >600 mg active acid/l, Cyprinodon variegatus.

Invertebrates: 48-hour EC50 value of 64 mg active acid/l, Acartia tonsa.

Algae: 72-hour EC50 value of 46 mg active acid/l, Pseudokirchneriella subcapitata.

Long-term data:

Invertebrates: 21-day NOEC and EC10 values of ≥106 and >106 mg active acid/l, respectively, Daphnia magna.

Algae: 72-hour NOEC value of 10 mg active acid/l, Pseudokirchneriella subcapitata.

It is known that a structural moiety of the cyclised constituent is analogous to some biologically important chemicals: c-HEBMP has a superficial resemblance to the components of phospholipids phosphoethanolamine, phosphocholine and phosphoserine. These latter materials are vital cell components and it is suggested that if c-HEBMP interferes with steps in their biosynthesis or action that this may lead to toxic effects.

In the REACH chemical safety assessment the assumption is therefore made that the cyclic constituent of the test substance is the cause of the toxic effects seen in aquatic organisms. The proportion of cyclic constituent of the salt present in the test is not known but would likely have been approximately 50% w/w of the test material. The PNEC is therefore derived on this basis from the most sensitive result (toxicity to algae). Hazard assessment should be conducted bearing in mind the whole substance as supplied and the available test results used a representative substance.

Additional information

The acid and sodium salts in the HEBMP category are freely soluble in water. The HEBMP anion can be considered fully dissociated from its sodium cation when in dilute solution. Under any given conditions, the degree of ionisation of the HEBMP species is determined by the pH of the solution. At a specific pH, the degree of ionisation is the same regardless of whether the starting material was HEBMP-H, HEBMP-xNa, or another salt of HEBMP.

 

Therefore, when a salt of HEBMP is introduced into test media or the environment, the following is present (separately):

  1. HEBMP is present as HEBMP-H or one of its ionised forms. The degree of ionisation depends upon the pH of the media and not whether HEBMP-xNa salt, HEBMP-H (acid form), or another salt was used for dosing.
  2. Disassociated sodium cations. The amount of sodium present depends on which salt was added.
  3. It should also be noted that divalent and trivalent cations would preferentially replace the potassium ions. These would include calcium (Ca2+), magnesium (Mg2+) and iron (Fe3+).

Categories Display