Iron digluconate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

migrated 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:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

GDL was diluted with demineralised water to obtain the desired concentrations.

Test organisms (species):

activated sludge

Details on inoculum:

Activated sludge of Rouen treatment plant system was taken the day of the essay (March 25th, 2010 for preliminary test and March 30th, 2010 for definitive test).
Activated sludge was washed twice with dechlorinated water and put back in suspension to obtain a concentration approximately 4 g/L (4.111 g/L for preliminary test and 3.944 g/L for definitive test).

This value gives a concentration approximately 1.6 g/L in the final volume.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20°C ± 2°C

Nominal and measured concentrations:

For definitive test theoretical concentration = 100.03625, 200.0725, 400.145, 800.29, 1600.58 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: flasks of 660mL
- No. of vessels per concentration (replicates): one per concentration
- No. of vessels per control (replicates): two vessels

TEST MEDIUM
Peptone (16.01699 g), beef extract (11.01693 g), urea (3.00898 g), Sodium chloride NaCl (0.70318 g), Calcium chloride CaCl2, 2H2O (0.40622 g), Magnesium sulphate MgSO4, 7H2O (0.20994 g), and DiPotassium hydrogenophosphate, KH2PO4 (2.79980 g) dissolved in demineralised water and completed to 1L.

EFFECT PARAMETERS MEASURED: After 3 hours of incubation, measured the respiration rate in each flask with an oxymeter during a maximum time of 12 minutes.

TEST CONCENTRATIONS
- Range finding study Test concentrations: 1.00039, 10.0039, 100.039, 1000.39, 10003.9 mg/L
- Range finding study Results used to determine the conditions for the definitive study: Yes

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

649.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: Confidence limits at 95% 321.1 – 978.5 mg/L

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

EC50 of 3,5-Dichlorophenol was between 5 and 30 mg/l (9.6 mg/l for definitive test).

Reported statistics and error estimates:

EC50 (Effect Concentration) and confidence limits were obtained by calculation according to linear regression (Probits).

Via read across Iron Gluconate is classified as non-hazardous for this end point

Validity criteria fulfilled:

yes

Conclusions:

Via read across Iron Gluconate is classified as non-hazardous for this end point

Executive summary:

Via read across Iron Gluconate is classified as non-hazardous for this end point

Description of key information

There are no toxicity to microorganisms studies on ferrous gluconate. Results of a study conducted with a structurally similar compoud, D-glucono-1,5-lactone , are reported and used for read across. 
Via read across Iron Gluconate is classified as non-hazardous for this end point

Key value for chemical safety assessment

EC50 for microorganisms:

649.8 mg/L

EC10 or NOEC for microorganisms:

100 mg/L

Additional information

Via read across Iron Gluconate is classified as non-hazardous for this end point

Iron Gluconate does not have any of the key properties that would alert for toxicity to microorganisms. The lack of an alert and the physical-chemical properties indicate that iron gluconate should not be toxic to microorganisms.

 

Removal of Iron Gluconate by means of activated sludge would be via a similar mechanism as for D-glucono-1,5-lactone; the biodegradation of the gluconate ion, not adsorption to sludge or volatilization. The LC50 figure for D-glucono-1,5-lactone is 650 mg/L. However, the confidence limits at 95% are between 321 – 979 mg/L. Iron Gluconate can be read across to D-glucono-1,5-lactone due to the comparable structures and relevant properties.

Full read across justification summary is attached to the end point summary