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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
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, conducted under GLP
Justification for type of information:
ANALOGUE APPROACH JUSTIFICATION
As few data are available on the target substance, a research of the potential analogues has been carried out.
The hypothesis is that properties are likely to be similar or follow a similar pattern as a result of the presence of a common metal ion (or ion complex including a hydrated metal ion). This is a reasonable assumption for the majority of inorganic compounds and some organic compounds (e.g. metal salts of some organic acids).
The following points are be considered:
- Chemical speciation and valency,
- 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.
- Counter ions: the assumption that the metal ion is responsible for the common property or effect implies that the toxicity of the counter ion present in the compound will be largely irrelevant in producing the effects to be assessed.
Based on these data, we have selected the analogue Strontium nitrate.
Strontium has also physiochemical properties similar to calcium and both appear mainly in ionic form in water.

A detail description is provided as attached report of this endpoint in this Iuclid file.
Reason / purpose for cross-reference:
read-across source
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 41.4 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
EC10
Effect conc.:
> 41.4 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Duration:
3 h
Dose descriptor:
NOEC
Effect conc.:
>= 41.4 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Details on results:
Difference between the controls was within 15% of each other
No inhibition of respiration rate (compared to the control) was noted in the test concentration of 100 mg test substance/L:
- % inhibition in replicate 1: 0%
- % inhibition in replicate 2: -2%
Results with reference substance (positive control):
the EC50 of 3,5-dichlorophenol was in the accepted range of 5-30 mg/L (i.e., 7.4 mg/L)
Reported statistics and error estimates:
a figure of more than 10% inhibition of respiration rate is considered significant. However, the test substance proved to be non-toxic at the tested concentration.
Validity criteria fulfilled:
yes
Conclusions:
An OECD-209-guideline test under GLP has been conducted, using strontium nitrate as test substance. A nominal test concentration of 100 mg/L (test substance) caused no effect; hence, the EC50 and EC10 are >100 mg/L test substance, and the NOEC is >= 100 mg/L test substance. These unbounded effect levels can be used for the estimation of a (worst-case) PNEC for micro-organisms.
Executive summary:

An OECD-209-guideline test under GLP has been conducted, using strontium nitrate as test substance. A nominal test concentration of 100 mg/L (test substance) caused no effect; hence, the EC50 and EC10 are >100 mg/L test substance, and the NOEC is >= 100 mg/L test substance.

This study was used in a read-across approach. These unbounded effect levels can be used for the estimation of a (worst-case) PNEC for micro-organisms for stonrium acetate.

Description of key information

An OECD-209-guideline test under GLP has been conducted, using strontium nitrate as test substance. A nominal test concentration of 100 mg/L (test substance) caused no effect; hence, the EC50 and EC10 are >100 mg/L test substance, and the NOEC is >= 100 mg/L test substance.

This study was used in a read-across approach. These unbounded effect levels can be used for the estimation of a (worst-case) PNEC for micro-organisms for stonrium acetate.

Key value for chemical safety assessment

EC50 for microorganisms:
41.4 mg/L
EC10 or NOEC for microorganisms:
41.4 mg/L

Additional information

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