Iron digluconate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24 October through the 27 October, 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Guideline:

ISO 10253 (Water quality - Marine Algal Growth Inhibition Test with Skeletonema costatum and Phaeodactylum tricornutum)

GLP compliance:

yes

Details on test solutions:

Nominal concentrations of the test material over a range of 56.2, 100.0, 177.8, 316.2, 562.3. and 1000.0 mg/L were prepared in Guillard's f/2 + Si test media from the stock solution.

Test organisms (species):

Skeletonema costatum

Details on test organisms:

Supplier: Culture Collection of Algae and Protozoa. Dunstaffnage

Stock cultures were maintained in Guillard's f/2 medium + Si in accordance with STL Runcorn SOP 1.18.

Test type:

static

Water media type:

saltwater

Total exposure duration:

3 d

Remarks on exposure duration:

Exposures were conducted between 24 October and 27 October 2000.

Post exposure observation period:

2 ml sub-samples of the contents of each test vessel were removed after 24, 48 and 72 hours of incubation and cell numbers determined according to STL Runcorn SOP III.19

Hardness:

No data

Test temperature:

20 ± 2°C

pH:

pH range 5.73-8.90

Dissolved oxygen:

Dissolved Oxygen range: 82.7-98.8 %

Salinity:

No data

Nominal and measured concentrations:

Nominal concentrations of the test material over a range of 56.2, 100.0, 177.8, 316.2, 562.3. and 1000.0 mg/L were prepared in Guillard's f/2 + Si test media from the stock solution.

Details on test conditions:

Six replicate control flasks and three replicate flasks at each test concentration and reference material, were prepared with algae added from a culture concentrate to give an initial algal cell concentration of approximately 8820 cells per ml. The culture flasks were incubated in a rotary incubator at a target temperature of 20 ± 2°C under constant illumination for 72 hours.

Reference substance (positive control):

yes

Remarks:

3,5- dichlorophenol

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

265.7 mg/L

Basis for effect:

growth rate

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

106.2 mg/L

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

88.2 mg/L

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

56.2 mg/L

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

100 mg/L

Basis for effect:

growth rate

Details on results:

From this study the 72 hour EC50 value tor the test substance was determined to be 265.7 mg/L. The 24 and 48 hour values were determined to be 106.2 and 88.2 mg/L respectively.

The No Observed Effect Concentration, (NOEC), after 72 hours was determined to be 56.2 mg/L. The Lowest Observed Effect Concentration. (LOEC), was determined to be 100.0 mg/L.

Concentrations of 316.2, 562.3, and 1000.0 mg/L produced greater than 100% inhibition after 24 hours exposure. After 48 hours exposure concentrations of 562.3 and 1000.0 mg/L produced greater than 100% inhibition. Greater than 100% inhibition was also evident at 1000.0 mg/L after 72 hours exposure. There was evidence of a dose response in this study.

Microscopic examination indicated no unusual cell growth or deformity at any of the test concentrations.

Reported statistics and error estimates:

The growth rate, u, was determined for each test flask using the following equation:

u= ( In Nn - In No )/ tn

tn = time of the final measurement (days) after the beginning of the test
No = the nominal, or measured, initial cell density
Nn= the measured final cell density at time. n

From the calculated growth rates the percentage inhibition, (Iui) for each test concentration was determined using the following equation:

Iui = ((Uc-Ui)/Uc) X 100

Iui = the percentage inhibition (growth rate) for test concentration i
Ui = the mean growth rate for test concentration i
Uc = the mean growth rate for the control

The concentration of test material required to cause 50% inhibition of growth rate (EC50) was determined using the statistical computer programme, Toxcalc, supplied by Tidepool Scientific. (STL Runcorn SOP V.4).

In this study the effective concentration of the test substance which inhibited the algal growth rate by 50% after 72 hours exposure (72 hour EC₅₀) was determined to be 265.7 mg/L. The pH readings for the test concentrations 56.2 - 1000.0 mg/L at the start of the study were below the acceptable tolerance limit of 7.80-8.20. pH for the test volumes was adjusted to within acceptable limits before the inoculum was added. It was noted that the test media changed from clear to a yellow/orange colouration upon addition of the test material. This increased with increasing concentration.

Conclusions:

The 72 hour EC50 for expsoure to iron gluconate to the algae Skeletonema costatum is 265.7 mg/L.

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

Executive summary:

In study, a sample of iron gluconate was assessed for its potential toxicity to the marine alga Skeletonema costatum in a static test over 72 hours according to the procedure described in ISO/DIS 10253 and as detailed in STL Runcorn SOP III. 19. Test concentrations were prepared over the range 56.2 to 1000.0 mg/L. Cultures of Skeletonema costatum were exposed to determine the concentration which inhibited algal growth rate by 50% over 72 hours (EC_5o). From this study the 72 hour EC₅₀ value was determined to be 265.7 mg/L. The 24 and 48 hour values were determined to be 106.2 and 88.2 mg/L respectively.

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

Description of key information

A sample of iron gluconate was assessed for its potential toxicity to the marine alga Skeletonema costatum in a static test over 72 hours according to the procedure described in ISO/DIS 10253 and as detailed in STL Runcorn SOP III. 19. Test concentrations were prepared over the range 56.2 to 1000.0 mg/L. Cultures of Skeletonema costatum were exposed to determine the concentration which inhibited algal growth rate by 50% over 72 hours (EC50). From this study the 72 hour EC50 value was determined to be 265.7 mg/L. The 24 and 48 hour values were determined to be 106.2 and 88.2 mg/L respectively.
Iron Gluconate is classified as non-hazardous for this end point

Key value for chemical safety assessment

EC50 for marine water algae:

265.7 mg/L

EC10 or NOEC for marine water algae:

56.2 mg/L