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Long-term toxicity to aquatic invertebrates

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Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1972
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Results are based on nominal values, and test did not exacty follow existing guidance (1972-study), but test method was well described and test conditions (e.g., test medium composition) were properly reported and monitored. The study meets generally accepted scientific standards. The NOEC is an estimated value based on ECHA methodology. Overall, the study should be considered reliable with restrictions.
Qualifier:
no guideline followed
Principles of method if other than guideline:
The test did not exacty follow an existing guidance (1972-study), but the test method was well described and test conditions (e.g. test medium composition) were properly reported and monitored. The test meets generally accepted scientific standards.
GLP compliance:
not specified
Analytical monitoring:
no
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Strain: laboratory clone
- Source: University of Michigan
- Age at study initiation (mean and range, SD): 12h +/- 12h
- Feeding during test: yes
- Type of food: 0.5 g of powdered dried grass and 10g of enriched trout-fry granules added to 250 mL of Lake Superior water and mixed vigorously in a blender for 5 minutes. This suspension was strained through #20 bolting cloth. The blender was then rinsed with an additional 50 mL of lake water, and the rinse water was added to the suspension. This suspension was stored in a refrigerator and mixed thoroughly each time an aliquot was withdrawn.
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
44-53 mg CaCO3/L
Test temperature:
18 +/- 1 °C
pH:
7.4-8.2
Dissolved oxygen:
+/- 9 mg/L
Salinity:
not reported
Details on test conditions:
TEST SYSTEM
- Test vessel: beaker
- Type (delete if not applicable): open 250 mL beaker, but covered with a pane glass to minimize evaporation
- Fill volume: 200 mL
- Renewal rate of test solution (frequency/flow rate): weekly renewal of test medium
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Lake Superior water; unfiltered water strained through a #20 bolting cloth
- Metals: 14 µg Ba/L ; 16 µg Sr/L ; 0.78 µg Zn/L ; <0.5 µg Ni/L ; 1.51 µg Cu/L ; <0.5 µg Co/L ; < 0.01 g Hg/L ; < 0.1 µg Cd/L
- Chloride: 1.22 mg/L
- Alkalinity: 42.3 mg/L as CaCO3
- Ca: 13.7 mg /L
- Mg: 3.12 mg/L
- K: 0.53 mg/L
- Na: 1.13 mg/L

OTHER TEST CONDITIONS
- Photoperiod: 16h light
- Light intensity: +/- 115 ft-c at the air-water interface



Reference substance (positive control):
no
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
2.9 mg/L
Nominal / measured:
nominal
Conc. based on:
other: metal ion
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
other: EC16
Effect conc.:
5.8 mg/L
Nominal / measured:
nominal
Conc. based on:
other: metal-ion
Basis for effect:
reproduction
Details on results:
According to ECHA methodology, the EC16 (i.e., effects situated between 10 and 20%) can be used to estimate a NOEC value; ECx (10% < x < 20%) /2 = NOEC. In this case, a NOEC of 2900 µg/L can be derived.

Other 21d-effect levels that were reported, these are the 21d-EC50 (reproduction) of 8900 µg/L and the 21d-LC50 of 13500 µg/L (12200-15000 µg/L). Endpoints are nor relevant for PNEC derivation, hence not included as K2-data points
Reported statistics and error estimates:
Results were statistically evaluated with the method of Litchfield and Wilcoxon (1949) for establishing approximations of the 95% confidence limits for survival. The terminology recommended by Sprague (1969) (i.e., LC), was used for survival and represents an interpolation from three or more partial-effect concentrations. Reproductive effects were analyzed in a similar manner excluding confidence limits, but are given in terms of reproductive impairments by percentage.

Chemical characteristics of Lake Superior water were monitored during the testing period according to procedures outlined by the American Public Health Association and procedures employing atomic absorption spectroscopy.

Conclusions:
Results are based on nominal values, and test did not exacty follow existing guidance (1972-study), but test method was well described and test conditions (e.g. test medium composition) were properly reported. The test meets generally accepted scientific standards. The NOEC was estimated based on ECHA methodology (i.e., EC16 / 2) and was 2.9 mg Ba/L.
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
The justification for read across is attached in IUCLID Section 13.
Reason / purpose:
read-across source
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
2.9 mg/L
Nominal / measured:
nominal
Conc. based on:
element (total fraction)
Remarks:
Ba
Basis for effect:
reproduction
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
5.51 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat. (total fraction)
Remarks:
Ba(NO)2
Basis for effect:
reproduction

Description of key information

A read across approach was followed to cover this endpoint for barium nitrate. The study from Biesinger and Christensen (1972), performed with barium chloride, yielded a 21-d EC16 for reproduction of Daphnia magna of 5.8 mg Ba/L. Using ECHA guidance, a NOEC of 2.9 mg Ba/L was derived from this value.  This result was recalculated to barium dinitrate based on the barium content of both substances (i.e. 5.51 mg barium trinitrate/L). 

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
2.9 mg/L

Additional information

A single relevant and reliable (Klimisch 2, reliable with restrictions) study was identified. The study (Biesinger and Christensen, 1972) performed a 21-d toxicity test with Daphnia magna using barium chloride as test substance. An EC16 of 5.8 mg Ba/L was reported for reproduction. Based on ECHA guidance, a NOEC was calculated from this value dividing the value by 2, yielding a 21-d NOEC of 2.9 mg Ba/L. The study was considered reliable with restrictions because no analytical monitoring of test substance concentrations was performed.