Registration Dossier
Registration Dossier
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EC number: 232-075-2 | CAS number: 7785-21-9
Toxicity to microorganisms
Administrative data
Link to relevant study record(s)
Description of key information
The influence of Diammonium hydrogenorthophosphate on the respiration rate of activated sludge was investigated after a contact time of 3 hours according to OECD guideline 209.Under the conditions of the test, Diammonium hydrogenorthophosphate was not toxic to waste water (activated sludge) bacteria at 100 mg/l. The 3-hour EC50 of Diammonium hydrogenorthophosphate exceeded 100 mg/l (based on nominal concentrations). The reported study is GLP-compliant and has Klimisch score 1.
Read across from diammonium phosphate to magnesium ammonium phosphate is considered justified based on following background:
Since both the magnesium ammonium phosphate and diammonium phosphate dissociate to their respective ammonium, (magnesium) and phosphate ions, it is considered acceptable to approach the assessment of magnesium ammonium phosphate based on the individual components.
Since Diammonium phosphate is very soluble in water and therefore much more bioavailable (588 g/l; The Merck Index“, 14th Edition, M. J. O’Neil (Editor), Merck Research Laboratories, Division of Merck & Co., Inc., Whitehouse Station, NY, USA (2006)) read across to the only slightly soluble magnesium ammonium phosphate (0.1 g/l) is considered as worst-case assumption. The only difference between the two inorganic salts is the replacement of one ammonia ion and one hydrogen ion by magnesium.
Magnesium from magnesium ammonium phosphate is not assumed to pose an additional risk for acute ecotoxicity since it is an essential mineral and ubiquitous present in food. Magnesium is the eighth most abundant element, constitutes about 2% af the Earth's crust by weight and is an essential element in biological systems, present in every cell type and organism.
The most common source of magnesium in groundwater is through the erosion of rocks, such as dolomite and minerals, such as magnesite. It is also
naturally present in sea water and salt deposits. It is found naturally in many foods such as vegetables, nuts, grains.
Key value for chemical safety assessment
- EC50 for microorganisms:
- 100 mg/L
- EC10 or NOEC for microorganisms:
- 100 mg/L
Additional information
The key study is GLP-compliant and has a Klimisch score of 1 .The measured value for EC50 of >100 mg/l is read across to magnesium ammonium phosphate. No further testing is required.
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