Sulphur trioxide

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Published investigative non-guideline, non-GLP study.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

read-across source

Qualifier:

no guideline available

Principles of method if other than guideline:

96-hour LC50 measurement

GLP compliance:

no

Remarks:

older, published study

Analytical monitoring:

yes

Details on sampling:

Not detailed

Vehicle:

no

Details on test solutions:

Not applicable

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

4 cm tail length obtained from a state fish hatchery in Louisiana. Maintained in groups of 30 in 38 L aquaria (51 x 32 x 27 cm)at pH 6.5 and temp. of 21 to 25 degrees C. Lighting was continuous and fish were fed tropical fish food or brine shrimp each evening.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Remarks on exposure duration:

Fish were exposed to each ph for 96 hours.

Post exposure observation period:

Not applicable

Hardness:

Not reported

Test temperature:

Presumed to be between 21 and 25 degrees C

pH:

pH was changed as appropriate during the study.

Dissolved oxygen:

Not reported

Salinity:

Not aplicable

Nominal and measured concentrations:

Test medium were amended with sulphuric acid to prepare the required pH of the test media.

Details on test conditions:

Not reported

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 16 - < 28 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

There was no mortality at pH 7.5, 5.0, 4.5, 4.0 or 3.5. Mortality was 100% at pH 3.25 and 3.0. The 96 hour LC50 was therefore between pH 3.25 and 3.5. Therefore the 96 h LC50 was between 16 and 28 mg/L.

No mortality was observed when the pH of the 3.0 aquarium was returned to pH 7.5 and fish were added to the aquaria.

Rate constants for locomotor activity before (pH7.5) and after (pH 4.0) exposure to sulphuric acid were 0.118 and 0.026 respectively, indicating that fish after acid exposure were only one quarter as active at pH 4.0 as they were at pH 7.5.

Results with reference substance (positive control):

No applicable.

Reported statistics and error estimates:

Not applicable

Sublethal observations / clinical signs:

The 96 hour LC50 for sulphuric acid to bluegill sunfish was determined to be between pH 3.25 and 3.5, equivalent to 16 to 28 mg/L.

Validity criteria fulfilled:

not applicable

Conclusions:

Based on the reported information an acceptable assessment of acute toxicity to fish was achieved.

Executive summary:

An acute toxicity with bluegill sunfish (Lepomis macrochirus) was conducted in which fish were exposed to series of pH decreasing from 7.5 to 3.25. There was no mortality at pH values of 7.5, 5.0, 4.5, 4.0 or 3.5 and 100% mortality at 3.25.

Rate constants for locomotor activity before (pH 7.5) and after (pH 4.0) exposure to sulphuric acid were 0.118 and 0.026 respectively, indicating that fish after acid exposure were only one quarter as active at pH 4.0 as they were at pH 7.5.

The 96 hour LC50 for sulphuric acid to bluegill sunfish was determined to be between pH 3.25 and 3.5, equivalent to 16 to 28 mg/L.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Published investigative non-guideline, non-GLP study.

Justification for type of information:

Sulphur trioxide readily reacts with water to form sulphuric acid. The reaction is instantaneous, to the extent that SO3 will react with water vapour in the atmosphere to form fumes of sulphuric acid. This reaction forms the basis of the manufacturing process of H2SO4. The read-across hypothesis is therefore that SO3 will instantaneously transform into H2SO4 upon contact with water (i.e. in aquatic ecotoxicology tests), thus any observed effects will be directly attributable to sulphuric acid. It is therefore justifiable to derive hazard conclusions from sulphuric acid data, with regard to ecotoxicological endpoints.

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

read-across source

Qualifier:

no guideline available

Principles of method if other than guideline:

96-hour LC50 measurement

GLP compliance:

no

Remarks:

older, published study

Specific details on test material used for the study:

Available study data for sulphuric acid is being used for read-across to the target substance, sulphur trioxide.

Analytical monitoring:

yes

Details on sampling:

Not detailed

Vehicle:

no

Details on test solutions:

Not applicable

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

4 cm tail length obtained from a state fish hatchery in Louisiana. Maintained in groups of 30 in 38 L aquaria (51 x 32 x 27 cm)at pH 6.5 and temp. of 21 to 25 degrees C. Lighting was continuous and fish were fed tropical fish food or brine shrimp each evening.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Remarks on exposure duration:

Fish were exposed to each ph for 96 hours.

Post exposure observation period:

Not applicable

Hardness:

Not reported

Test temperature:

Presumed to be between 21 and 25 degrees C

pH:

pH was changed as appropriate during the study.

Dissolved oxygen:

Not reported

Salinity:

Not aplicable

Nominal and measured concentrations:

Test medium were amended with sulphuric acid to prepare the required pH of the test media.

Details on test conditions:

Not reported

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 16 - < 28 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

There was no mortality at pH 7.5, 5.0, 4.5, 4.0 or 3.5. Mortality was 100% at pH 3.25 and 3.0. The 96 hour LC50 was therefore between pH 3.25 and 3.5. Therefore the 96 h LC50 was between 16 and 28 mg/L.

No mortality was observed when the pH of the 3.0 aquarium was returned to pH 7.5 and fish were added to the aquaria.

Rate constants for locomotor activity before (pH7.5) and after (pH 4.0) exposure to sulphuric acid were 0.118 and 0.026 respectively, indicating that fish after acid exposure were only one quarter as active at pH 4.0 as they were at pH 7.5.

Results with reference substance (positive control):

No applicable.

Reported statistics and error estimates:

Not applicable

Sublethal observations / clinical signs:

The 96 hour LC50 for sulphuric acid to bluegill sunfish was determined to be between pH 3.25 and 3.5, equivalent to 16 to 28 mg/L.

Validity criteria fulfilled:

not applicable

Conclusions:

Based on the reported information an acceptable assessment of acute toxicity to fish was achieved.

Executive summary:

Data on the acute toxicity to freshwater fish is available for sulphuric acid and is considered suitable for read-across (based on the analogue approach) to the target substance, sulphur trioxide. Sulphur trioxide readily reacts with water to form sulphuric acid. The reaction is instantaneous, to the extent that SO₃ will react with water vapour in the atmosphere to form fumes of sulphuric acid. This reaction forms the basis of the manufacturing process of H₂SO₄. The read-across hypothesis is therefore that SO₃ will instantaneously transform into H₂SO₄ upon contact with water (i.e. in aquatic ecotoxicology tests), thus any observed effects will be directly attributable to sulphuric acid. It is therefore justifiable to derive hazard conclusions from sulphuric acid data, with regard to ecotoxicological endpoints.

An acute toxicity with bluegill sunfish (Lepomis macrochirus) was conducted in which fish were exposed to series of pH decreasing from 7.5 to 3.25. There was no mortality at pH values of 7.5, 5.0, 4.5, 4.0 or 3.5 and 100% mortality at 3.25.

Rate constants for locomotor activity before (pH 7.5) and after (pH 4.0) exposure to sulphuric acid were 0.118 and 0.026 respectively, indicating that fish after acid exposure were only one quarter as active at pH 4.0 as they were at pH 7.5.

The 96 hour LC50 for sulphuric acid to bluegill sunfish was determined to be between pH 3.25 and 3.5, equivalent to 16 to 28 mg/L.

Description of key information

A published paper on the effects of sulphuric acid on a freshwater fish, bluegill sunfish (Lepomis macrochirus) has been summarised and a 96 hour LC50 obtained.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

> 16 - < 28 mg/L

Additional information

Read-across from studies performed with sulphuric acid is proposed.

An acute toxicity with bluegill sunfish (Lepomis macrochirus) was conducted in which fish were exposed to series of pH decreasing from 7.5 to 3.25. There was no mortality at pH values of 7.5, 5.0, 4.5, 4.0 or 3.5 and 100% mortality at 3.25. The 96 hour LC50 for sulphuric acid to bluegill sunfish was determined to be between pH 3.25 and 3.5, equivalent to 16 to 28 mg/L.