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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
no data
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The reaction mass of sulphuric acid, hydrogen peroxide and peroxomonosulphuric acid is predominantly sulphuric acid (>80%). Although all constituents of the reaction mass contribute towards and are essential for the desired technical effects of the range, it is considered acceptable to read-across to data on sulphuric acid. This because significant toxicological effects are likely to be masked in the multi-constituent substance by its corrosive nature and so it considered appropriate to read across to the mean constituent, sulphuric acid, when considering aquatic toxicity.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See read-across data matrix under 'Attached background material' below.

3. ANALOGUE APPROACH JUSTIFICATION
See read-across data matrix under 'Attached background material' below.

4. DATA MATRIX
See read-across data matrix under 'Attached background material' below.
Qualifier:
no guideline followed
Principles of method if other than guideline:
All stages of the life cycle of the midge Tanytarsus dissimilis were subjected to low pH and extremes of tolerance were determined.
GLP compliance:
no
Remarks:
study pre-dates GLP
Analytical monitoring:
yes
Details on sampling:
- During the testing period the pH was checked and corrected, if needed, twice per day using a standard laboratory pH meter.
Vehicle:
no
Details on test solutions:
- Static bio-assays were conducted to evaluate the toxicity of low pH to T. dissimilis.
- Six 8 gallon glass aquaria filled with carbon filtered Lake Superior water were used.
Test organisms (species):
other: Tantytarsus dissimilis
Details on test organisms:
- The test species was selected because of its widespread distribution, value as food for fish, ease of rearing in the laboratory, and its relatively short life cycle.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
45 d
Post exposure observation period:
- Study extended to three complete generations at pH 5.0, 6.0 and 7.8
Hardness:
Refer to physical and chemical data for test water (below)
Test temperature:
18.5 ± 1 °C
pH:
- Test systems: pH 3.0, 4.0, 5.0, 5.5 and 6.0 (measured)
- Control: pH 7.8 (measured)
Dissolved oxygen:
- Refer to physical and chemical data for test water (below)
-Test water was not aerated because adeqate oxygen was produced by algae.
Salinity:
Not applicable
Nominal and measured concentrations:
See pH conditions (above)
Details on test conditions:
- Fifteen larvae of T. dissimilis and a mixed culture of algae (90 % Scenedesmus sp; 10 % other genera) were introduced into each aquarium.
- To prevent outside contamination and escape of the adults, a tightly fitting glass lid was placed on top of each aquarium.
- To encourage growth of algae, fluorescent light with one wide-spectrum Gro-lux and one Cool-white lamp were used to provide 162 ft-c of illumination as measured photometrically at the surface of the water.
- Utilising a 16 h (lights on) photoperiod, the oxygen levels provided by the algae ranged from 7.7 to 9.0 mg/L.
- During the 8 h night (lights off) oxygen levels dropped to 4.1 to 5.2 mg/L as measured 30 min before the lights came on.
Reference substance (positive control):
no
Dose descriptor:
NOEC
Effect conc.:
0.15 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: equivalent to pH 5.5
Details on results:
- Normal daily deviation in pH did not exceed 0.1 units.
- Oxygen levels varied only slightly throughout the testing period.
- After 5 d several larvae at pH 4.0 were dead and the rest appeared to be under stress.
- At pH 5.5, 6.0 and the control aquarium, all larvae survived and began pupating at 12 to 14 d.
- Adults began to appear after 27 d at pH 5.5, 6.0 and 7.8. All 15 larvae from each concentration emerged successfully within 35 days.
- At pH 5.0, no adults had emerged within 35 d. Five of the pupal cases were removed an examined and it was found that the larvae had pupated successfully and adult characteristics were present. However, the adults were unable to escape the pupal case. The 10 remaining larvae were kept under test conditions for an additional 10 d but no adults appeared.
- All tests at pH 5.5, 6.0 and the control were allowed to continue and three complete generations were obtained. Numbers increased from 15 to between 500 and 550 larvae at each of these pH values.
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
Not applicable

JUSTIFICATION FOR USE OF READ-ACROSS DATA

See comparison of overall physico-chemical and toxicity profiles for target and source chemicals in the data matrix (attached).

PHYSICAL AND CHEMICAL DATA FOR TEST WATER AFTER 35 DAYS

pH

Temperature (°C)

Disolved O2(mg/L)

Free CO2(mg/L)

Total acidity (CO2+ H2SO4) (mg/L)

Total alkalinity (mg/L)

Total hardness (mg/L)

3.0

18.5

7.71

16.7

69.0

0.0

78.0

4.0

18.5

8.06

12.6

41.0

0.0

64.0

5.0

18.5

7.93

8.4

21.0

2.0

54.0

5.5

18.5

8.70

4.9

19.0

9.0

54.0

6.0

18.5

8.54

3.7

11.0

12.0

50.0

7.8

18.5

9.01

1.5

3.0

40.0

50.0

EFFECTS OF LOW pH ON LIFE CYCLE

pH

Effect

3.0

All larvae died within 5 days.

4.0

All larvae died within 10 days.

5.0

Larvae survived, pupae formed, adults failed to emerge within 45 days.

5.5

Larvae survived, pupae formed, adults emerged, eggs hatched within 35 days.

6.0

Larvae survived, pupae formed, adults emerged, eggs hatched within 35 days.

7.8

Larvae survived, pupae formed, adults emerged, eggs hatched within 35 days.

Validity criteria fulfilled:
not applicable
Conclusions:
The No Observed Effect Concentration (NOEC) for Tanytarsus dissimilis exposed to sulphuric acid was found to be pH 5.5 based on reproduction.

Description of key information

NOEC 0.15 mg/L (pre-GLP assessment of Tanytarsus dissimilis exposed to sulphuric acid)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
0.15 mg/L

Additional information

Sulphuric acid, peroxomonosulphuric acid and hydrogen peroxide are each expected to contribute to the physico-chemical properties of the multi-constituent substance. However, significant toxicological effects are likely to be masked in the multi-constituent substance by its corrosive nature. It is therefore considered appropriate to read-across to the main constituent, sulphuric acid, when considering aquatic toxicity (NOEC equates to pH 5.5)

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