Iron digluconate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: screening test, other

Remarks:

Biodegradability in Seawater

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 October 2000 to 7 November 2000

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Followed OECD Guideline 306 but missing some information in report

Qualifier:

according to guideline

Guideline:

other: OECD 306 (Closed Bottle Procedure)

GLP compliance:

yes

Remarks:

Followed UK GLP Regulations 1997

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on inoculum:

All test bottles contained coarse filtered, natural seawater as inoculum. For each of the sample days, duplicate bottles were prepared for each of the test material concentrations and reference material. Three repIicates for the control vessels were prepared. During the study, all bottles were incubated at 17.0-19 .5°C, in the dark.

Natural seawater was collected from Penrhyn Point in North Wales on 27th September 2000. The temperature at collection was 16.7°C, pH 8.13, salinity 28.5 g/L and the dissolved oxygen level 91.6%. After collection the seawater was coarse filtered and maintained in the dark. The seawater was aged prior to use by gentle aeration, at 20± 2°C.

Duration of test (contact time):

28 d

Initial conc.:

6 mg/L

Initial conc.:

7.5 mg/L

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test Vessel: Completely filled, sealed glass BOD bottles of nominal 272 ml volume.

Dissolved oxygen (DO) concentrations were measured on sample days 0, 3, 7, 14, 21 and 28. Duplicate bottles of each concentration of test material, and bottles containing the reference compound (sodium benzoate) were measured. On each occasion three blank bottles were also measured.

Reference substance:

other: Sodium benzoate

Parameter:

% degradation (O2 consumption)

Value:

ca. 79.3

Sampling time:

28 d

Remarks on result:

other: Concentration 6.0 mg/L

Parameter:

% degradation (O2 consumption)

Value:

ca. 78.4

Sampling time:

28 d

Remarks on result:

other: Concentration 7.5 mg/L

Details on results:

The results at both 6.0 mg/L and 7.5 mg /L indicated that under these conditions, the test substance showed good potential for degradation. At 28 days the calculated percentage degradation values were 79.3% at a concentration of 6.0 mg/L and 78.4% at 7.5 mg/L.

Parameter:

COD

Value:

0.66 mg O2/g test mat.

Biochemical Oxygen Demand of Test Substance

02 Depletion ( mg BOD/L)	Day 3	Day 7	Day 14	Day 21	Day 28
Test material 6.0 mg/L  BODx= (mao- max ) - (mdo- mdx)	1.62	2.48	2.65	3.05	3.14
Test material 7.5 mg/L BODx= (mb0- mbx)- (mdo- mdx)	1.71	2.72	2.92	3.32	3.88
Reference- 2.50 mg/L sodium benzoate BODx= (mco- mcx) - (mdo- mdx)	2.68	3.09	3.21	3.28	2.81

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

Readily biodegradable based on 28 day oxygen consumption of 79.3% and 78.4%.

Executive summary:

In this study, the test substance was assessed for the rate and extent of biodegradation when exposed to marine microorganisms for 28 days according to the method detailed in STL Runcorn SOP III.36 and in accordance with OECD guideline 306.

The results indicated that, under the test conditions detailed, the test material showed good potential for degradation in the marine environment at the concentrations tested. At 28 days the calculated percentage degradation values were 79.3% at a concentration of 6.0 mg/L and 78.4% at 7.5 mg/L.

Description of key information

Readily biodegradable based on 28 day oxygen consumption of 79.3% and 78.4%.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window

Additional information

In this study, the test substance was assessed for the rate and extent of biodegradation when exposed to marine microorganisms for 28 days according to the method detailed in STL Runcorn SOP III.36 and in accordance with OECD guideline 306.

The results indicated that, under the test conditions detailed, the test material showed good potential for degradation in the marine environment at the concentrations tested. At 28 days the calculated percentage degradation values were 79.3% at a concentration of 6.0 mg/L and 78.4% at 7.5 mg/L.