Magnesium oxalate

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

Study period:

1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information in a detailed justification report is included as attachment to the same record.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
For the determination of analogue in this read-across approach, the following points have been considered:
- Chemical speciation and valency (common magnesium cation: Mg2+).
- The water solubility, as it provides a first indication of the availability of the metal ion in the different compartments of interest. The most simplistic approach to hazard evaluation is to assume that the specific metal-containing compound to be evaluated shows the same hazards as the most water-soluble compounds.
- In fluids of organisms and in aqueous media, dissociation of magnesium oxalate takes place immediately, resulting in formation of magnesium cations (Mg2+) and oxalate anions. Thus, any ingestion or absorption of magnesium oxalate by living organisms, in case of systemic consideration, will inevitably result of exposure to the dissociation products.
- Magnesium is an abundant mineral naturally present in the body. It is a cofactor in more than 300 enzyme systems that regulate diverse biochemical reactions in the body, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation (IOM 1997, Rude 2010, Rude 2012). Magnesium is required for the normal functioning of several biochemical and physiological reactions and pay an essential role in the human body (Rude 2012). An adult body contains approximately 25 g magnesium, with 50% to 60% present in the bones and most of the rest in soft tissues (Volpe 2012). Human Recommended Dietary Allowances (RDA) for magnesium is up to 420mg per day (IOM 1997). For the same reasons (involvement in biochemical and physiological functions), magnesium is also naturally present in various organisms of the environment such as fish, crustacea or vegetables. Besides they are identified as food sources of magnesium (US 2012). Consequently, it can be concluded that magnesium is of low (eco)toxicological relevance when ingested and taken up systemically. Thus, any possible toxicological or ecotoxicological effect triggered by magnesium oxalate exposure can be attributed to oxalate anion.
- Counter ions: the assumption that the oxalate ion is responsible for the common property or effect implies that the toxicity or ecotoxicity of the counter ion present in the compound will be largely irrelevant in producing the effects to be assessed.
- Likely common breakdown products via physical and/or biological processes for the targeted substance (magnesium oxalate) and the analogues identified cannot present strong differences since the structures are very simple and very similar (formation of Mg2+ or oxalate ion).

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source chemical information is provided in the “source” endpoint. No impurity affecting the classification is reported for the source chemical.
Information on the impurities of the target chemical are detailed in the attached report.

3. ANALOGUE APPROACH JUSTIFICATION
The main hypothesis for the analogue approach are verified. They are presented in the detailed report attached. The experimental data performed on the substance (tests performed in this REACH registration dossier on strontium peroxide) confirms the analogue approach performed (same results on analogues).

4. DATA MATRIX
A data matrix is presented in the detailed report attached.

Reason / purpose for cross-reference:

read-across source

Duration:

48 h

Dose descriptor:

LC0

Effect conc.:

250 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

325 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC100

Effect conc.:

400 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC0

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

160 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC100

Effect conc.:

250 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Conclusions:

The 48h LC50 values were determined to be 160mg/L and 325mg/L for oxalic acid. In a read-across approach, this value is considered for magnesium oxalate.

Executive summary:

Two 48h LC50 values corresponding to 325 mg/L and 160 mg/L have been determined in two laboratories for the effects of oxalic acid on mortality of the freshwater fish Leuciscus idus melanotus under the test conditions defined according to guideline Deutsche Einheitsverfahren zur Wasser, Abwasser und Schlamm-Untersuchung L 15 Fischtest.

In a read-across approach, this study is considered reliable and the value is used for magnesium oxalate.

Description of key information

Two 48h LC50 values corresponding to 325 mg/L and 160 mg/L have been determined in two laboratories for the effects of oxalic acid on mortality of the freshwater fish Leuciscus idus melanotus under the test conditions defined according to guideline Deutsche Einheitsverfahren zur Wasser, Abwasser und Schlamm-Untersuchung L 15 Fischtest.

In a read-across approach, this study is considered reliable and the value is used for magnesium oxalate.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

160 mg/L