Registration Dossier

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
other:
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
According to REACH Annex VII column 2, 9.1.2. Growth inhibition study aquatic plants (algae preferred), the study does not need to be conducted if there are mitigating factors indicating that aquatic toxicity is unlikely to occur for instance if the substance is highly insoluble in water or the substance is unlikely to cross biological membranes.

In general, there is no legal limit value available defining a substance as poorly water soluble or insoluble under REACH. However, in ECHA’s Guidance document Chapter R.7b: Endpoint specific guidance Version 3.0 – February 2016, it is stated: „poorly water soluble substances (e.g. water solubility below 1 mg/L or below the detection limit of the analytical method of the test substance)“. Further, poorly soluble substances are defined by OECD (2000 OECD SERIES ON TESTING AND ASSESSMENT, Number 23, GUIDANCE DOCUMENT ON AQUATIC TOXICITY TESTING OF DIFFICULT SUBSTANCES AND MIXTURES, ENV/JM/MONO(2000)6) as substances with a limit of solubility <100 mg/l although technical problems are more likely to occur at <1mg/l as defined in TGD (1996). Very low water solubility (i.e. in the low μg/l range) could be used as a reason to significantly modify a standard test or to test non-pelagic organisms preferentially.
ECHA’s Guidance document Chapter R.7c: Endpoint specific guidance Version 3.0 – June 2017 further says: „As indicated in the OECD TG 305, for strongly hydrophobic substances (log Kow > 5 and a water solubility below ~ 0.01-0.1 mg/L), testing via aqueous exposure may become increasingly difficult. However, an aqueous exposure test is preferred for substances that have a high log Kow but still appreciable water solubility with respect to the sensitivity of available analytical techniques, and for which the maintenance of the aqueous concentration as well as the analysis of these concentrations do not pose any constraints.

The water solubility is < 11.2 µg/L for the test item resp. < 1 mg/l for the analyte, i.e. iron, so the criteria mentioned above are met. Further, the criterion for “below the detection limit of the analytical method of the test substance” is also met. The establishment and validation of the analytical method was properly performed.
The detection limit of the analytical method is (ICP-OES) is 0.001 mg/l Fe, working range of the ICP-OES is actually 0.005 – 1 mg/l.
Ecotoxicity tests are performed in media containing various supplements and biological material, which is expected to lower the sensitivity of the analytical method. Hence, quantification of the test item up to its water solubility in ecotoxicity test media could like not be performed at all. So, the required analytics for ecotoxicity testing, both short and long-term, are technically not feasible, and testing does not need to be conducted.

Summarizing, a study of the acute toxicity of the registered substance to algae does not need to be conducted, as it is considered both not technically feasible and no additional information on classification and labelling could be retrieved, and the study can be omitted.
Cross-reference
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:
2018-01-15 - 2018-01-19
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
GLP compliance:
yes
Type of method:
column elution method
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: sponsor

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Refrigerated (5 ± 3°C)
Key result
Water solubility:
<= 11.2 µg/L
Conc. based on:
test mat.
Temp.:
20 °C
Remarks on result:
other: pH value not available
Water solubility:
<= 1 µg/L
Conc. based on:
element
Remarks:
Fe
Temp.:
20 °C
Remarks on result:
other: Analytical method was established with Fe as analyte
Conclusions:
Water solubility of the test item was performed according to OECD 105 under GLP using the column elution method, which was chosen as the substance was considered to have a water solubility below 10E-2 g/L. Quantification of the solved material was performed using ICP-OES by determination of the iron contained in the test item. An iron concentration of 1 μg/L corresponds to about 11.2 μg/L for the idealized structure of the test item. So, the method is considered suitable and the results are considered sufficiently reliable. The water solubility of the test item is below or equal to the detection limit of the analytical method (1 μg/L Fe) and hence appears insoluble in water. With reference to column 2 of Annex VII to REACH “If the substance appears ‘insoluble’ in water, a limit test up to the detection limit of the analytical method shall be performed”, the water solubility of the test item is reported as ≤11.2 μg/L. So the substance must be considered insoluble in water.
Executive summary:

The test item was analysed for water solubility according to OECD Guideline 105 under GLP, using the column elution method.

The concentration of the test item in the collected fractions was calculated from the iron content determined by ICP-OES.

The water solubility of the test item is below or equal to the detection limit of the analytical method (1 μg/L Fe) and hence appears insoluble in water.

An iron concentration of 1 μg/L corresponds to about 11.2 μg/L for the idealized structure of the test item.

With reference to column 2 of Annex VII to REACH “If the substance appears ‘insoluble’ in water, a limit test up to the detection limit of the analytical method shall be performed”, the water solubility of the test item is reported as ≤11.2 μg/L.

(See also “Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint specific guidance”, Version 6.0, July 2017, page 66ff).

The water solubility of the test item was determined to ≤11.2 μg/L.

The water solubility was determined at 20 °C. The pH value of the collected aqueous fractions could not be determined since HNO3 was immediately added for stabilization.

Data source

Materials and methods

Results and discussion

Applicant's summary and conclusion