Reaction products of boric acid and calcium dihydroxide and lithium hydroxide

Endpoint summary

Description of key information

Variations in structure (trigonal vs tetrahedral) between the substances are not expected to lead to any changes as at physiological pH as all the substances dissociate to provide the same common compounds. Read-across to the result for dilithium tetraborate is proposed.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Systemic mammalian toxicity will be influenced by the degree to which the substances are capable of being absorbed via the appropriate route of exposure.

At physiological pH, the substances dissociate and release boric acid and lithium/calcium ions as a result of relevant transformation pathways. It will be the boric acid component of the substances which will drive the mammalian toxicity endpoints.

The target UVCB substance has a higher precursor molar ratio for lithium hydroxide than for calcium hydroxide, and therefore the precautionary principle should be applied and read across from dilithium tetraborate where relevant to consider the worst case.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

500 mg/kg bw

Based on:

test mat.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

At physiological pH, the substances dissociate and release boric acid and lithium/calcium ions as a result of relevant transformation pathways. It will be the boric acid component of the substances which will drive the mammalian toxicity endpoints.

The target UVCB substance has a higher precursor molar ratio for lithium hydroxide than for calcium hydroxide, and therefore the precautionary principle should be applied and read across from dilithium tetraborate where relevant to consider the worst case.

Read-across to the result for dilithium tetraborate is proposed for this endpoint which quotes an oral LD50 value for dilithium tetraborate in Wistar rats in the range of 300-2000 mg/kg body weight. The same result is therefore quoted for Reaction products of boric acid and calcium dihydroxide and lithium hydroxide.

Executive summary:

The oral LD50 value of dilithium tetraborate in Wistar rats was established to be within the range of 300-2000 mg/kg body weight. According to the OECD 423 test guideline, the LD50 cut-off value was considered to be 500 mg/kg body weight.

 

Based on these results, dilithium tetraborate should be classified as Category 4 based on GHS criteria. Variations in structure (trigonal vs tetrahedral) between the substances are not expected to lead to any changes as at physiological pH as all the substances dissociate to provide the same common compounds.

 

The target UVCB substance has a higher precursor molar ratio for lithium hydroxide than for calcium hydroxide, and therefore the precautionary principle should be applied and read across from dilithium tetraborate where relevant to consider the worst case. Therefore Reaction products of boric acid and calcium dihydroxide and lithium hydroxide should be classified as acute toxicity, category 4.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

500 mg/kg bw

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Systemic mammalian toxicity will be influenced by the degree to which the substances are capable of being absorbed via the appropriate route of exposure.

At physiological pH, the target and source substances have been demonstrated to dissociate and release boric acid and lithium/calcium ions as a result of relevant transformation pathways (hydrolysis). It will be the boric acid component of the substances which will drive the mammalian toxicity endpoints. In order to minimise animal testing, one substance in each category was tested in support of EU REACH registration, dilithium tetraborate and calcium metaborate. For all other substances in these categories, read-across is proposed. Consequently, for the UVCB target substance that releases boric acid as well as the lithium and calcium ions, read-across is proposed.

The target UVCB substance has a higher precursor molar ratio for lithium hydroxide than for calcium hydroxide, and therefore the precautionary principle should be applied and read across from dilithium tetraborate where relevant to consider the worst case.

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Interpretation of results:

GHS criteria not met

Conclusions:

At physiological pH, the substances dissociate and release boric acid and lithium/calcium ions as a result of relevant transformation pathways. It will be the boric acid component of the substances which will drive the mammalian toxicity endpoints.

The target UVCB substance has a higher precursor molar ratio for lithium hydroxide than for calcium hydroxide, and therefore the precautionary principle should be applied and read across from dilithium tetraborate where relevant to consider the worst case.


Therefore read-across to the result for dilithium tetraborate is proposed for this endpoint which quotes an oral LD50 value for dilithium tetraborate which exceeds 2000 mg/kg body weight. The same result is therefore quoted for Reaction products of boric acid and calcium dihydroxide and lithium hydroxide

Executive summary:

The dermal LD50 value of Dilithium tetraborate in Wistar rats was established to exceed 2000 mg/kg body weight. Based on these results, dilithium tetraborate does not have to be classified and has no obligatory labelling requirement for acute dermal toxicity according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2015) (including all amendments) and Regulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures (including all amendments).

 

Variations in structure (trigonal vs tetrahedral) between the substances are not expected to lead to any changes as at physiological pH as all the substances dissociate to provide the same common compounds. It can be concluded that all substances in the categories : lithium salts of the oxyacids of boron (B); and calcium salts of the oxyacids of boron (B) including the UVCB  Reaction products of boric acid and calcium dihydroxide and lithium hydroxide should not be classified.

Justification for classification or non-classification

Based on these results, dilithium tetraborate should be classified as Category 4 based on GHS criteria. Variations in structure (trigonal vs tetrahedral) between the substances are not expected to lead to any changes as at physiological pH as all the substances dissociate to provide the same common compounds.

 

The target UVCB substance has a higher precursor molar ratio for lithium hydroxide than for calcium hydroxide, and therefore the precautionary principle should be applied and read across from dilithium tetraborate where relevant to consider the worst case. Therefore Reaction products of boric acid and calcium dihydroxide and lithium hydroxide should be classified as acute toxicity, category 4.

 

No classification is required for acute dermal toxicity.