Phosphonic acid, calcium salt (2:1)

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

In the assessment of calcium dihydrogenphosphite (Ca(H2PO3)2, CAS 13780-04-6), a read-across approach is followed based on the information available for potassium phosphonate (KH2PO3/K2HPO3 EC 915-179-9). This read-across strategy is based on the hypothesis that the phosphite anion is the driver for the ecotoxicological and toxicological effects of both salts.The read-across hypothesis is justified by the immediate dissociation of calcium dihydrogenphosphate and potassium phosphonate upon dissolution in aqueous media. Both phosphite salts are highly soluble (>200 g/L) and are only present in their dissociated form in solution, i.e. the calcium or potassium cation and the phosphite anion. The transformation of the salts into the ions is rapid and complete in relevant environmental and physiological media and therefore no systemic exposure to the salts as such occurs. Exposure to the non-common cations (Ca2+ and K+) does not influence the prediction of the (eco)-toxicity because both elements are abundantly present in natural environments and emissions from these salts do not significantly increase the exposure concentration for calcium and potassium. Moreover, calcium and potassium are major essential element for living organisms.Further information is included as attachment in section 13 of IUCLID.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

> 135 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Remarks:

dihydrogenphosphite anion

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 135 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

act. ingr.

Remarks:

dihydrogenphosphite anion

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

> 168 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 168 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Validity criteria fulfilled:

yes

Conclusions:

LC0 and LC50 > 168 mg Ca(H2PO3)2 /LResults indicate that KH2PO3/K2HPO3 did not induce short-term toxicity to fish up to 200 mg/L. Values were corrected for Ca(H2PO3)2 based on the assumption that the phosphite anion is the active ingredient reposonsible for the effects, resulting in predicted LC0 and LC50 values of >168 mg/L.

Executive summary:

A full test under static conditions was performed to evaluate the effect of Potassium phosphonate (KH2PO3/K2HPO3) on zebra fish (Danio Rerio) (Tediosi E., 2013).

The fish were checked for mortality and abnormalities in appearance and behaviour after 2, 24, 48, 72 and 96 hours.

In the negative control no mortality was observed during the test period. This value complies with the validity criterion reported in the guidelines (maximum mortality of one fish, if seven fish are used, in the negative control medium at the end of the test).

No effect was observed until 200 mg/L. Values were corrected for Ca(H2PO3)2 based on the assumption that the phosphite anion is the active ingredient reposonsible for the effects, resulting in predicted LC0 and LC50 values of >168 mg/L.

Description of key information

LC50 and LC0 > 168 mg Ca(H2PO3)2 /L

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

168 mg/L

Additional information

A full test under static conditions was performed to evaluate the effect of Potassium phosphonate (KH2PO3/K2HPO3) on zebra fish (Danio Rerio) (Tediosi E., 2013).

The fish were checked for mortality and abnormalities in appearance and behaviour after 2, 24, 48, 72 and 96 hours.

In the negative control no mortality was observed during the test period. This value complies with the validity criterion reported in the guidelines (maximum mortality of one fish, if seven fish are used, in the negative control medium at the end of the test).

No effect was observed until 200 mg potassium phosphonate /L. Values were recalculated for Ca(H2PO3)2 based on the assumption that the phosphite anion is the active ingredient reposonsible for the effects, resulting in predicted LC0 and LC50 values of >168 mg Ca(H2PO3)2 /L.