Magnesium oxalate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study (OECD), GLP compliance.

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

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

162.2 mg/L

Basis for effect:

mobility

Quality criteria have been satisfied:

% of Daphnie immobilized present in control: 0

 

Analytical verification of the concentration of the test substance

The test substance is considered stable, because the HPLC-UV values, at the beginning and at the

end of the test, at lower and higher concentration, remain within the required range, so results are

referred to the nominal concentration.

The percentage stability for lower concentration is 99%

The percentage stability for higher concentration is 100%

The results are reported in the Appendix 5.

 

EC50

EC50was evaluted using EPA Probit analysis program version1.5.

 

On the basis of results, interpreted according with OECD guideline N° 202, the test substance

“OXALIC ACID DI-HYDRATE” has an EC50(48h) of 162.2 mg/l.

Validity criteria fulfilled:

no

Conclusions:

The 48h EC50 was 162.2 mg/l. This result is used for magnesium oxalate.

Executive summary:

Daphnia magna were exposed to oxalic acid during 48 h according to the guideline OECD TG 202 in a GLP laboratory test. An 48 h EC50 of 136.9 mg/l was determined. This study is considered relevant in a read across purpose and the result is used for the assessment of magnesium oxalate.

Description of key information

Daphnia magna were exposed to oxalic acid during 48 h according to the guideline OECD TG 202 in a GLP laboratory test. An 48 h EC50 of 136.9 mg/l was determined. This value is used in a read across approach.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

162.2 mg/L