Sulphuric acid

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

Sodium sulphate will dissociate under aqueous conditions to form sodium and sulphate ions, whereas sulphuric acid dissociates in solution to form hydrogen and sulphate ions. Both substances therefore dissociate into similar compounds (i.e. sulphate ions), with the main difference being the generation of sodium and hydrogen ions in sodium sulphate and sulphuric acid, respectively. It is therefore justifiable to derive hazard conclusions for sulphate ions generated from the dissociation of sulphuric acid from sodium sulphate data, with regard to ecotoxicological endpoints.

Reason / purpose for cross-reference:

read-across source

Specific details on test material used for the study:

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

Duration:

37 d

Dose descriptor:

NOEC

Effect conc.:

ca. 26 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

A NOEC of approximately 26 g/L is reported under the conditions of this study.

Validity criteria fulfilled:

not applicable

Conclusions:

A NOEC of approximately 26 g/L is reported for sodium sulphate, incidating that sulphate is essentially non-toxic to activated sludge.

Executive summary:

Sodium sulphate will dissociate under aqueous conditions to form sodium and sulphate ions, whereas sulphuric acid dissociates in solution to form hydrogen and sulphate ions. Both substances therefore dissociate into similar compounds (i.e. sulphate ions), with the main difference being the generation of sodium and hydrogen ions in sodium sulphate and sulphuric acid, respectively. It is therefore justifiable to derive hazard conclusions for sulphate ions generated from the dissociation of sulphuric acid from sodium sulphate data, with regard to ecotoxicological endpoints.

The authors investigated the effects of inorganic salts (inclduing sodium sulphate) on bacteria in activated sludge. A NOEC of approximately 26 g/L is reported for sodium sulphate, incidating that sulphate is essentially non-toxic to activated sludge.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-standard published study.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Non-standard study investigating effects on bacteria in sewage sludge

GLP compliance:

no

Remarks:

: older published study, pre-dates GLP

Specific details on test material used for the study:

Sodium sulphate will dissociate under aquoeus conditions to form sodium and sulphate ions.

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

activated sludge

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

37 d

Test temperature:

18.5-22.5 C

Dissolved oxygen:

6-8 mg/L

Nominal and measured concentrations:

Concentrations: concentrations were increased from 8 to 35 g/l over a time period of 37 days. Concentration steps were 2 - 5 g/l.

Reference substance (positive control):

no

Duration:

37 d

Dose descriptor:

NOEC

Effect conc.:

ca. 26 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

A NOEC of approximately 26 g/L is reported under the conditions of this study.

Validity criteria fulfilled:

not applicable

Conclusions:

A NOEC of approximately 26 g/L is reported for sodium sulphate, incidating that sulphate is essentially non-toxic to activated sludge.

Executive summary:

The authors investigated the effects of inorganic salts (inclduing sodium sulphate) on bacteria in activated sludge. A NOEC of approximately 26 g/L is reported for sodium sulphate, incidating that sulphate is essentially non-toxic to activated sludge.

Reference 3

Endpoint:

activated sludge respiration inhibition testing

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

Sodium sulphate will dissociate under aqueous conditions to form sodium and sulphate ions, whereas sulphuric acid dissociates in solution to form hydrogen and sulphate ions. Both substances therefore dissociate into similar compounds (i.e. sulphate ions), with the main difference being the generation of sodium and hydrogen ions in sodium sulphate and sulphuric acid, respectively. It is therefore justifiable to derive hazard conclusions for sulphate ions generated from the dissociation of sulphuric acid from sodium sulphate data, with regard to ecotoxicological endpoints.

Reason / purpose for cross-reference:

read-across source

Specific details on test material used for the study:

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

Duration:

30 d

Dose descriptor:

NOEC

Effect conc.:

>= 30 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Validity criteria fulfilled:

not specified

Conclusions:

A NOEC of approximately 30 g/L is reported for sodium sulphate.

Executive summary:

Sodium sulphate will dissociate under aqueous conditions to form sodium and sulphate ions, whereas sulphuric acid dissociates in solution to form hydrogen and sulphate ions. Both substances therefore dissociate into similar compounds (i.e. sulphate ions), with the main difference being the generation of sodium and hydrogen ions in sodium sulphate and sulphuric acid, respectively. It is therefore justifiable to derive hazard conclusions for sulphate ions generated from the dissociation of sulphuric acid from sodium sulphate data, with regard to ecotoxicological endpoints.

The authors investigated the effects of salinity on bacteria in sewage sludge. A NOEC of approximately 30 g/L is reported for sodium sulphate, confirming the essentially low toxicity of sulphate to bacteria in sewage sludge.

Reference 4

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-standard published study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Non-standard study investigating effects on bacteria in sewage sludge.

GLP compliance:

no

Remarks:

: older, published study

Specific details on test material used for the study:

Sodium sulphate will dissociate under aqueous conditions to form sodium and sulphate ions.

Analytical monitoring:

no

Vehicle:

not specified

Test organisms (species):

activated sludge

Test type:

static

Water media type:

freshwater

Total exposure duration:

40 d

Test temperature:

20-23C

pH:

7-7.5

Dissolved oxygen:

2.3-3.5 mg/L

Nominal and measured concentrations:

concentrations were increased from 10 to 40 g/l over a time period of ca. 40 days. Concentration steps were 10 g/l.

Details on test conditions:

TEST SYSTEM - Concentrations: concentrations were increased from 10 to 40 g/l over a time period of ca. 40 days. Concentration steps were 10 g/l. - Exposure vessel: 10 l - Analyses: effluent analyses were done according to APHA standard methods. - pH: 7 - 7.5 - Temperature: 20 - 23 degree C - Dissolved oxygen: 2.3 - 3.5 mg

Reference substance (positive control):

no

Duration:

30 d

Dose descriptor:

NOEC

Effect conc.:

>= 30 g/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Validity criteria fulfilled:

not specified

Conclusions:

A NOEC of approximately 30 g/L is reported for sodium sulphate.

Executive summary:

The authors investigated the effects of salinity on bacteria in sewage sludge. A NOEC of approximately 30 g/L is reported for sodium sulphate, confirming the essentially low toxicity of sulphate to bacteria in sewage sludge.

Reference 5

Endpoint:

toxicity to microorganisms, other

Remarks:

Microcosm study investigating chronic effects of pH of protozoa, bacteria and algae

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Published non-standard study investigating pH effects

Qualifier:

no guideline followed

Principles of method if other than guideline:

Investigation of pH effects in a microcosm study.

GLP compliance:

no

Remarks:

: published, non-guideline study

Analytical monitoring:

no

Vehicle:

yes

Test organisms (species):

other: total bacteria

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

5.34 other: pH

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: pH

Basis for effect:

other: bacterial abundance

Remarks on result:

other: 100 mg/L

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

6.61 other: pH

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: pH

Basis for effect:

other: bacterial abundance

Remarks on result:

other: 88 mg/L

Bacterial abundance decreased at pH levels of 5.34 and less. The concentration of sulphuric acid added to the test systemic to achieve this pH was 100 mg/L. No effect was seen on bacterial abundance at pH levels of 6.61 and above (88 mg/L).

Validity criteria fulfilled:

not applicable

Conclusions:

Bacteria were shown to be relatively insensitive to the effects of acid pH under the conditions of this study.

Executive summary:

The authors investigated the chronic effects of pH of protozoa, bacteria and algae in a microcosm study using sulphuric acid as a test substance. Bacterial abundance was shown to decrease at pH levels of <= 5.34 (100 mg/L sulphuric aicd), with no effects seen at pH 6.61 (88 mg/L sulphuric acid). Bacteria were shown to be relatively insensitive to the effects of acid pH under the conditions of this study.

Description of key information

Available non-standard data for the read-across compound sodium sulphate report NOECs for bacteria in sewage sludge of 26 -30 g/L.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

26 000 mg/L

Additional information

Sulphate is inherently non-toxic to bacteria and is used by strains of anaerobic bacteria as an energy source. Sulphate reducing bacteria are required for the anaerobic digestion of raw sewage sludge. Sulphate is included as a component of the synthetic sewage feed defined by OECD 209. The toxic effects of sulphuric acid will therefore be driven by pH. Available non-standard data for the read-across compound sodium sulphate report NOECs for bacteria in sewage sludge of 26 -30 g/L. Niederlehner & Cairns (1990) investigated the chronic effects of pH of protozoa, bacteria and algae in a microcosm study using sulphuric acid as a test substance. Bacterial abundance was shown to decrease at pH levels of <= 5.34 (100 mg/L sulphuric acid), with no effects seen at pH 6.61 (88 mg/L sulphuric acid). Bacteria were shown to be relatively insensitive to the effects of acid pH under the conditions of this study.