Registration Dossier
Registration Dossier
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EC number: 701-325-7 | CAS number: -
Toxicity to microorganisms
Administrative data
Link to relevant study record(s)
Description of key information
The NOEC of 500 mg Fe/L is set equal to 1429 mg submission item dry matter/L.
Key value for chemical safety assessment
Additional information
Iron
A number of results for iron salts are available for microbial inhibition, in several species and with varying reliability. In some cases the acidic pH (4-5) was noted by the reporting authors. The observed effects may be associated with the intrinsic acidity of Fe (III) salts.
Ferrous and ferric iron salts are used as flocculation and precipitation agents in mechanical and biological waste water treatment units. According to experience, under normal conditions, these applications of these substances cause no disturbances in the normal operation of the biological degradation, which is clear evidence of an absence of inhibitory effects within the normal loading range.
Inhibition of cellular respiration in activated sludge biomass was observed, with an IC50of ca. 500 mg FeCl3/L (equivalent to 172 mg Fe(III)/L) under conditions where the pH was not adjusted to neutralise pH effects (Broglio 1987). This was a non-standard shortened test and some details of test conduct and conditions are not reported, so the result is of non-assignable reliability. The author concluded that effects on aquatic micro-organisms appear to be related to the pH of the test medium, which decreases significantly as more iron is added; pH fell to ca. 5.7 at the 500 mg/L loading from a baseline pH of ca. 7.4.
A result of 782 µmol/L has been reported by Calleja et al (1994) using photobacteria (Photobacterium phosphoreum). The level corresponds to 43.7 mg Fe/L, but is of little relevance for the derivation of PNECstp.
Evidence for concentrations of 200-500 mg Fe/L activated sludge in the course of normal levels of use of iron salts in WWTP is available from company documentation (Kronos International Inc 2000). Overall there is substantial evidence to assume a NOEC to activated sludge of 500 mg Fe/L.
Manganese
This major constituent contribute in the order of < 10% to the total metal molarity of the submission item. The metal is considered have no effects up to levels of 500 mg Mn/L and thus being not of particular toxicity. As the threshold levels of the submission item will be based on the total dry mass no further assessment applies to manganese. These considerations will be checked with the published information on the dissemination page of the European Chemical Agency ECHA.
The hazard to the aquatic life is assessed on the basis of a Species Sensitivity Distribution (SSD) calculation (see discussion on Aquatic toxicity).
Aluminium
One activated sludge respiration inhibition test is available (Schwarz 2008). This test was performed with aluminium chloride (CAS 7446-70-0) according to the OECD TGD 209 protocol. No effects were seen up to the highest test concentration of 1000 mg test material/L. The test substance contained 20 g Al/100 g and the test concentrations can be converted to mg/L Al. 1000 mg/L test material is equal to 202 mg Al/L. As no effects were seen the threshold levels of the submission item will be based on the total dry mass no further assessment applies.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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