Calcium nitrite

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Data waiving:

study technically not feasible

Justification for data waiving:

the study does not need to be conducted because the substance has a low octanol water partition coefficient and the adsorption potential of this substance is related to this parameter

Justification for type of information:

Please refer to the attached docuement for the justification of the data waiver, text copied below:

CALCIUM NITRITE DATA WAIVER FOR ADSORPTION/DESORPTION

Adsorption of Calcium Nitrite to soil particles is not expected due to very high solubility in water and very low partition coefficient.

Due to the ionic nature of the compound, in aqueous solution it is expected to disassociate almost completely into its component species – Ca2+ ions and NO2- ions.

Due to being strongly charged, ionic species are extremely hydrophilic/lipophobic and it is expected to only be soluble in non-polar solvents to an extremely low degree, and to be highly soluble in water. These facts are basic tenets of chemistry and are borne out in all related chemistry literature.

Indeed it is considered of questionable value to perform partition coefficient testing on inorganic, ionic compounds as due to the above factors, the outcome can reliably predicted to be zero or very close to zero.

However in order to support the data waiver for adsorption/desorption, a partition coefficient test was performed (Report attached) and the resulting Kow value was 0.003

Combined with the tested water solubility that exceeded 500g/L, we feel that this strongly supports the data waiver for adsorption/desorption.

To further flesh-out the waiver it should be noted that nitrite is naturally-occurring in aquatic ecosystem and the role of the nitrite ion in the ecological nitrogen cycle is well documented in historical literature, proving that the nitrite species is readily biodegraded. The Calcium ion is of course, non-reducible, but is on its own a benign and naturally occurring mineral species, being present in all natural fresh and saltwater sources.

And in accordance with the standard information requirements for REACH:




And further to that, when performing adsorption/desorption studies, the primary endpoint variable is the “Organic carbon normalised adsorption coefficient (Koc)”.

As Calcium Nitrite does not contain any carbon whatsoever, it is not technically possible to make this measurement.


In conclusion then, Calcium Nitrite:
• Has a practically-determined Kow value of 0.003
• Has a practically-determined solubility in water exceeding 500g/L
• Is composed of ionic species that are naturally occurring and/or readily biodegradable
• Due to the above properties, can reasonably be expected to have a very low potential for adsorption and a high mobility in soil/sediment
• Is not a suitable compound for adsorption/desorption testing

Therefore, in this way we waive the need to perform adsorption/desorption testing on this substance.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Deviations:

no

GLP compliance:

yes

Type of method:

flask method

Partition coefficient type:

octanol-water

Key result

Type:

Pow

Partition coefficient:

ca. 0.003

Temp.:

20 °C

pH:

ca. 8

Conclusions:

In a guideline study, the value of Kow for calcium nitrite was determined to be 0.003 at 20°C.

Executive summary:

In an OECD guideline study (18-0489), conducted according to GLP, the value of Kow for calcium nitrite (at 20^oC and using the shake flask method) was determined to be 0.003

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

23 January - 9 March 2018 [several physical-chemical studies]

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Good quality study, conducted to GLP. The reporting deficiencies are not expected to influence the validity of the result.

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

The pH was not reported.

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

The pH was not reported.

GLP compliance:

yes

Type of method:

other: gravimetric procedure based on the results of a preliminary test

Water solubility:

> 500 g/L

Conc. based on:

test mat.

Temp.:

20 °C

Remarks on result:

other: The pH was not reported.

Details on results:

Addition of 2 mL purified water to approximately 2 g of test item resulted in 96.02 and 96.05% solubles in the two respective replicates. The solubility was therefore confirmed to exceed 500 g/L. No further testing was considered necessary.

Conclusions:

In a guideline GLP study, the water solubility of anhydrous calcium nitrite was determined to exceed 500 g/L (i.e. highly soluble).

Executive summary:

In an OECD guideline study (TG 105), conducted according to GLP, the water solubility of anhydrous calcium nitrite (estimated in a preliminary test and subsequently confirmed by gravimetric analysis conducted in duplicate) was determined to be greater than 500 g/L. As such, calcium nitrite is considered to be highly soluble.