4-O-β-D-galactopyranosyl-D-glucitol

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1980

Report date:

1980

Reference 2

Reference Type:

other: Published secondary source

Title:

Lactitol

Author:

WHO/FAO

Year:

1983

Bibliographic source:

WHO/FAO: Expert Committee on Food Additives Summary of Toxicological Data of Certain Food Additives Series 18 (http://www.inchem.org/documents/jecfa/jecmono/v18je10.htm)

Materials and methods

Test guideline

Test guideline 1

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Deviations:

yes

Remarks:

not specified

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.5 (Degradation: Biochemical Oxygen Demand)

Version / remarks:

carried out according to Dutch standard method (NEN3235-5.4)

Deviations:

not specified

Test guideline 3

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.6 (Degradation: Chemical Oxygen Demand)

Version / remarks:

carried out according to Dutch standard method (NEN3235-5.3)

Deviations:

not specified

Principles of method if other than guideline:

A die-away test (modified OECD-screening test), chemical- (COD) and biochemical oxygen demand (BOD) determinations were carried out to determine the biodegradability of Lactitol. In the die-away test, biodegradation was based on dissolved organic carbon analysis (DOC). The modified OECD-screening test was also carried out, because normally COD and BOD findings underestimate biodegradation of carbohydrates.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

4-O-β-D-galactopyranosyl-D-glucitol

EC Number:

209-566-5

EC Name:

4-O-β-D-galactopyranosyl-D-glucitol

Cas Number:

585-86-4

Molecular formula:

C12H24O11

IUPAC Name:

4-O-beta-D-galactopyranosyl-D-glucitol

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Test substance name: lactitoldihydrate
- Source and lot/batch number of test material: CCA; tests described in this report were carried out with a sample of the homogenized lot sent to CIVO-TNO.

Study design

Oxygen conditions:

anaerobic

Inoculum or test system:

sewage, domestic, adapted

Details on inoculum:

Settled effluent from a sewage purification plant receiving only domestic sewage was used as the inoculum.

Duration of test (contact time):

2 d

Details on study design:

Medium, inoculum, and test or control substance were added to 300 mL Erlenmeyer flasks (in duplicate). The flasks were incubated on a rotary shaker at 23±1°C. Samples for analysis were taken at the start of the test and after 2, 5, 7, 9, 12, 14, and 16 days. Suspended solids were removed by centrifuging the samples for 10 minutes at 500000 x g in stainless steel tubes. The dissolved organ carbon content of the samples was determined using a Beckmann Total Organic Carbon Analyser.

The degradation (%) was calculated according to the following formula:
% biodegradation = [ (co - ct) ÷ co ] x 100
where :
co is the DOC content at the start of the experiment.
ct is the DOC content at time t.

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (DOC removal)

Value:

0

Sampling time:

0 d

% Degradation 2

Parameter:

% degradation (DOC removal)

Value:

94

Sampling time:

2 d

% Degradation 3

Parameter:

% degradation (DOC removal)

Value:

84

Sampling time:

5 d

% Degradation 4

Parameter:

% degradation (DOC removal)

Value:

88

Sampling time:

7 d

% Degradation 5

Parameter:

% degradation (DOC removal)

Value:

84

Sampling time:

9 d

% Degradation 6

Parameter:

% degradation (DOC removal)

Value:

71

Sampling time:

12 d

% Degradation 7

Parameter:

% degradation (DOC removal)

Value:

93

Sampling time:

14 d

Details on results:

The somewhat irregular results of the lactitol degradation are most probably due to the death of the biomass formed during degradation and the subsequent release of soluble organic matter. This can, in turn, be metabolized by other micro-organisms finally leading to exhaustion of the system. The same sort of irregularities occur in the inoculum blank. The inoculum blank was neglected in the calculation of the biodegradation.

As expected, the test substance appeared to be non-toxic at the concentration tested; this is demonstrated by the identical results for the biodegradation of the test substance/acetate mixture and acetate alone. The results of the BOD and COD determinations and of the degradability test seem to be in contradiction. After five days only just over 50% of the amount of oxygen theoretically needed to oxidize the test substance had been used up completely, although the test substance was ultimately degraded (based on DOC) in this period. Compounds like the test substance are used for a substantial part during degradation for growth of micro-organisms (synthesis of cell materials) and for this reason oxygen consumption is less than expected although degradation is complete. The substance must therefore be considered readily biodegradable.

BOD5 / COD results

BOD5 / COD

BOD5 / COD 1

Key result

Parameter:

COD

Value:

955 mg O2/g test mat.

BOD5 / COD 2

Key result

Parameter:

BOD5

Value:

550 mg O2/g test mat.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

A die-away test (modified OECD-screening test), chemical- (COD) and biochemical oxygen demand (BOD) determinations were carried out to determine the biodegradability of Lactitol. The values for COD and BOD5 were 955 and 550 mg/g Lactitol respectively. In the die-away test, biodegradation based on dissolved organic carbon analysis (DOC) was complete in two days. For this reason, Lactitol is considered readily biodegradable.

Executive summary:

A die-away test (modified OECD-screening test), chemical- (COD) and biochemical oxygen demand (BOD) determinations were carried out to determine the biodegradability of Lactitol. In the die-away test, biodegradation was based on dissolved organic carbon analysis (DOC). The modified OECD-screening test was also carried out, because normally COD and BOD findings underestimate biodegradation of carbohydrates. The values for COD and BOD5 were 955 and 550 mg/g lactitol respectively. In the die-away test, biodegradation based on dissolved organic carbon analysis (DOC) was complete in two days. For this reason, lactitol is considered readily biodegradable.