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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1991-05-15 to 1991-05-31
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP, Guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Version / remarks:
adopted April 4, 1984
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.2 (Acute Toxicity for Daphnia)
Version / remarks:
adopted September 19, 1984
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- The test media were prepared using stock solutions of 100 mg/L by adding quantitatively 99.7 mg of test substance to 1000 mL DWS (Dutch standard water). Ultra sonication was used to accelerate the dissolving of the test substance. The final test solutions ranged from clear to turbid without substance deposits at the start of the exposure. The concentrations of the test item actually prepared were: 5.6, 10, 18, 32, 56, and 100 mg/L.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia (Daphnia magna, Crustacea, Cladocera (Straus, 1820))
- Source: laboratory breed
- Age at study initiation (mean and range, SD): < 24 hours
- Method of breeding:
-- Start of each batch: With newborn animals, i.e. less than 3 days old, by placing about 250 of them into 10 litres of medium in all-glass culture vessel.
-- Maximum age of the cultures: 4 weeks
-- Renewal of the cultures: After 7 days of cultivation half of the medium twice a week.
-- Feeding: daily, a suspension of fresh water algae
-- Temperature of medium: 18 - 22°C, constant within +/- 1°C
-- Validity of batch: Frequent inspection of the cultures with respect to number of young, appearance of young and parental daphnia and global feeding behaviour.
- Feeding during test: no feeding
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
210 mg CaCO3/L (11.8°DH)
Test temperature:
20.5 to 21.5 °C
pH:
The initial pH increased with test concentrations from 8.2 in the controls to 8.8 at 100 mg/L. After 48 hours pH was 8.3 or 8.4.
Dissolved oxygen:
> 5 mg/L for all measurements
Salinity:
The test medium DWS had the following ion composition:
- Ca2+: 54.4 mg/L
- Mg2+: 17.5 mg/L
- Na+: 27.4 mg/L
- K+: 7.8 mg/L
Cl-: 96.6 mg/L
SO4(2-): 70.1 mg/L
Nominal and measured concentrations:
nominal: O (control), 5.6, 10, 18, 32, 56, 100 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL, all-glass
- No. of organisms per vessel: 10
- No. of vessels per concentration: 2 per concentration, except at 56 mg/L (only one vessel)
- No. of vessels per control: 2
- Introduction of young daphnia: Directly after preparation of the test media daphnia were introduced into the test medium.
- Illumination: 16 hours photoperiod daily

EFFECT PARAMETERS MEASURED:
- Immobility (including mortality): At 24 hours and 48 hours. Those animals not able to swim within 15 seconds after gentle agitation of the test vessel are considered to be immobile.
- Dissolved oxygen content and pH: At the beginning and at the end of the test, for all concentrations and the control(s)
- Temperature of media: Daily in control vessel, beginning at the start of the test.

RANGE FINDING STUDY:
- Test concentrations: Daphnia were exposed for 48 hours to a concentration range of 0.1 to 100 mg/L forming a geometric progression with a factor of 10.
- Results used to determine the conditions for the definitive study: 100 % immobility of daphnia was recorded at nominally 100 mg/L. No biologically significant immobility was seen at or below nominally 10 mg/L.

ACCEPTABILITY OF THE TEST:
- In the control, not more than 10 % of the daphnia should have been immobilised or trapped at the surface of the water.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
38 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks on result:
other: 95 % confidence interval: 29.8 to 51.8 mg/L
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
26.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks on result:
other: 95 % confidence interval: 22.8 to 32.2 mg/L
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Details on results:
Immobility in test groups:
- after 24 hours: 100 % at 100 mg/L, 60 % at 56 mg/L, 50 % at 32 mg/L. No immobilisation of daphnia was seen at or below 18 mg/L.
- after 48 hours: 100 % at 56 and 100 mg/L, 65 % at 32 mg/L, and 15 % at 18 mg/L. No immobilisation of daphnia was seen at or below 10 mg/L.

Immobility in negative of control:
- after 24 hours and 48 hours: 0 %, no daphnia became immobilized or trapped at the surface of the water
Results with reference substance (positive control):
- Results with reference substance valid?: yes
- EC50 for the reference substance potassium dichromate:
-- 24 h: 1.64 mg/L, which is within the expected range of 1.0 to 2.4 mg/L (n=60)
-- 48 h: 1.11 mg/L, which is within the expected range of 0.6 to 1.9 mg/L (n=60)
Executive summary:

Acute toxicity of substance "reaction mass of calcium hydrogen phosphonate and dialuminium tricalcium hexaoxide" (90 % a.i.) to daphnia magna was studied under static conditions according to OECD Guideline 202, adopted April 4, 1984 and EU method C-2, adopted September 19, 1984. Daphnids were exposed at nominal concentrations of 0 (control), 5.6, 10, 18, 32, 56, and 100 mg/L for 48 hours. 

Based on immobilization, the 24-h EC50 was 38.0 mg/L with 95 % confidence interval ranging from 29.8 to 51.8 mg/L, and the 48-h EC50 was 26.3 mg/L with 95 % confidence interval ranging from 22.8 to 32.2 mg/L. The 48-h NOEC based on immobilization was 10 mg/L.  

This study is classified as acceptable and satisfies the guideline requirements of OECD Guideline 202 and EU method C-2 for an acute toxicity study with freshwater invertebrates.

Description of key information

A reliable, relevant and adequate study according to OECD Guideline 202, adopted April 4, 1984 and EU method C-2, adopted September 19, 1984 is available.

The 48-h EC50 for daphnia magna was 26.3 mg/L with 95 % confidence interval ranging from 22.8 to 32.2 mg/L.
The dissociation of the substance in water will result in common environmental constituents - calcium, aluminium, phosphate. Calcium and phosphate are essential for almost all living organisms including fresh- and saltwater invertebrates and natural constituents of their habitats. Aluminium as most abundant metallic element of the earth´s crust, is also a natural component in environmental habitats. Therefore, the substance is not expected to have a relevant intrinsic toxic activity to aquatic organisms.
Noticed toxicity is most probably triggered by a pH effect. Dissociation of the reaction mass under the conditions of OECD Guidelines 112 or 105, resulted in a pKa of 10.1 and a pH of 11.4, respectively. A temporary pH effect as toxicodynamic reason for aquatic toxicity of inorganic alkaline substances dissolving in common environmental constituents has been discussed in detail in the EU Risk Assessment on sodium hydroxide and in several OECD HPV SIDS documents on alkaline substances. In general, natural waters do have a sufficient buffering capacity to overcome this effect (c. f. EU RAR sodium hydroxide, 2007; http: //echa. europa. eu/documents/10162/0ded9c53-4082-405b-b09a-e16e57e158af) or e. g. http: //www. inchem. org/documents/sids/sids/Naco. pdf). Therefore, substance "reaction mass of calcium hydrogen phosphonate and dialuminium tricalcium hexaoxide" is not expected to have a relevant intrinsic toxic activity to aquatic organisms and PNECs will not be derived.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
26.3 mg/L

Additional information

Acute toxicity of substance "reaction mass of calcium hydrogen phosphonate and dialuminium tricalcium hexaoxide" (90 % a.i.) to daphnia magna was studied under static conditions according to OECD Guideline 202, adopted April 4, 1984 and EU method C-2, adopted September 19, 1984. Daphnids were exposed at nominal concentration of 0 (control), 5.6, 10, 18, 32, 56, and 100 mg/L for 48 hr. Immobilization was observed daily.  The 24-h EC50 was 38.0 mg/L with 95 % confidence interval ranging from 29.8 to 51.8 mg/L, and the 48 -hour EC50 was 26.3 mg/L with 95 % confidence interval ranging from 22.8 to 32.2 mg/L. The 48-h NOEC based on immobilization was 10 mg/L. 

 

This study is classified as acceptable and satisfies the guideline requirements of OECD Guideline 202 and EU method C-2 for an acute toxicity study with freshwater invertebrates.

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