Inositol phosphates

Ecotoxicological Summary

Additional information

As the test material is imported in the tonnage band 1 -10 tonnes per annum, a chemical safety assessment will not be required. Hence, the PNEC levels were not calculated.

Synthetic inositol phosphates are composed of a mix of inositol phosphates (26.7 – 38.4%) and orthophosphoric acid (23.8 – 26%). The toxicity to algae of this substance can therefore be determined based on data on these two components :

·        Inositol phosphates: A study conducted on a substance (‘Inositol phosphates from rice bran’) containing a comparable amount of inositol phosphates (26.8 - 29.1%) but less orthophosphoric acid (0.4 – 1%) yielded a 72 h ErC50 for Desmodesmus subspicatus equivalent to 55 mg/L(based on nominal concentrations as the substance degraded rapidly in the test medium). Read-across between the two substances is considered possible as their inositol phosphate content and physico-chemical properties (e.g. water solubility, log Kow, melting/freezing point, boiling point, relative density and surface tension) were shown to be in the same ranges.

·        Orthophosphoric acid: Toxicity to algae from orthophosphoric acid is not expected. Indeed, orthophosphoric acid is a source of phosphate, a nutrient that is essential to algae growth. In large concentrations, phosphate causes excessive growth of algae rather than toxicity. Also, the presence of orthophosphoric acid does not significantly decrease the pH of the substance compared to ‘Inositol phosphate from rice bran’, as both have a pH below 1 in undiluted form. No specific pH-related toxicity will therefore occur.

 

In conclusion, the toxicity to algae of ‘Synthetic inositol phosphate’ is expected to be comparable to that of ‘Inositol phosphates from rice bran’, with a 72h ErC50 = ca. 55 mg/L.

The toxicity to Daphnia of this substance can be determined as follows :

·        Inositol phosphates: A study conducted on a substance (‘Inositol phosphates from rice bran’) containing a comparable amount of inositol phosphates (26.8 - 29.1%) but less orthophosphoric acid (0.4 – 1%) yielded a 48 h LC50 for Daphnia magna > 100 mg/L (based on nominal concentrations as the substance degraded rapidly in the test medium). Read-across between the two substances is considered possible as their inositol phosphate content and physico-chemical properties (e.g. water solubility, log Kow, melting/freezing point, boiling point, relative density and surface tension) were shown to be in the same ranges.

·        Orthophosphoric acid: According to the IUCLID 2000 dataset (http://ecb.jrc.ec.europa.eu/IUCLID-DataSheets/7664382.pdf), toxicity to Daphnia of orthophosphoric acid is related to pH, not to the substance itself. Because the presence of orthophosphoric acid in ‘Synthetic inositol phosphates’ does not significantly alter the pH compared to ‘Inositol phosphates from rice bran’ (both substances have a pH <1 in undiluted form), no difference in toxicity specifically due to orthophosphoric acid is expected. Orthophosphoric acid has been shown to present low toxicity to fish, with a 96h LC50 for mosquito fish = 138 mg/L (http://www.hillbrothers.com/msds/pdf/n/phosphoric-acid-fg.pdf).

 

In conclusion, the toxicity to Daphnia of ‘Synthetic inositol phosphate’ is expected to be comparable to that of ‘Inositol phosphates from rice bran’, with a 48h LC50 > 100 mg/L.

Conclusion on classification

Based on the results from the read-across studies on daphnia and algae, it can be concluded that synthetic inositol phosphates does not require any environmental classification. The reason behind non-classification is that the criteria for acute category 1 (72 h ErC50 ≤ 1 mg/L) is not met with by the test material.