Kombucha

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

Temperature in the experiment (range 19.6 – 22.0 °C) and during pre-culture incubation (range 19.4 – 25.2 °C). As all validity criteria were met and exponential growth was observed in the blank control these deviations were stated as uncritical.

GLP compliance:

yes (incl. QA statement)

Remarks:

GLP compliance statement and Quality assurance unit statement available in the study report

Test material

Test material information

Constituent 1

Reference substance name:

Fermentation product of sucrose and Theaceae Camellia Camellia sinensis leaves with a variable symbiosis of bacteria and yeast, of including bacteria of Acetoacteraceæ Acetobacter and Gluconobacter genus, and yeasts of Saccharomycetaceae family

Molecular formula:

Not applicable

IUPAC Name:

Fermentation product of sucrose and Theaceae Camellia Camellia sinensis leaves with a variable symbiosis of bacteria and yeast, of including bacteria of Acetoacteraceæ Acetobacter and Gluconobacter genus, and yeasts of Saccharomycetaceae family

Test material form:

liquid

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Study design

Test type:

static

Water media type:

other: algal medium (demineralised water enriched with minerals but without algae)

Limit test:

no

Total exposure duration:

72 h

Test conditions

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (K2Cr2O7, CAS No. 7778-50-9)

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

244.12 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

205.94 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

yield

Effect concentrations 3

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1 892.33 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: Dissolved Organic Carbon

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

486.22 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

yield

Effect concentrations 5

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

yield

Effect concentrations 7

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

320 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

growth rate

Effect concentrations 8

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

320 mg/L

Nominal / measured:

meas. (geom. mean)

Basis for effect:

yield

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

According to OECD 201 test, algal 72h-EC50 for Kombucha (Fermentation product of sucrose and Camellia sinensis (Theaceae) leaves with a variable symbiosis of bacteria and yeast, including various Acetoacteraceæ bacteria and Saccharomycetaceae yeasts) is 1892.33 mg/l.

Executive summary:

One valid experiment was performed.

The study was performed using 5 concentrations ranging from 0.1 to 10 g/L (nominal). Incubation time (test system Desmodesmus subspicatus) was 72 hours. The cell concentration of each replicate was determined by measuring the cell numbers every 24 ± 1 hours with an electronic cell counter. Growth rate µ and the yield were determined from the cell number at the respective observation times.

Significant inhibition of algal growth was observed at all tested concentrations with exception of lowest concentration 0.1 g/L.

The inhibition in the two highest concentrations was in the same range. For the most accurate determination of the EC₁₀ and EC₅₀ values by regression analysis, the highest concentration was therefore excluded from the statistical evaluation.

At the start and at the end of the test, the content of the test item in the test solutions was estimated by determination of the total organic carbon (TOC) content in the test solutions using a carbon analyser. The TOC concentrations in the test solutions were in a range between 2.9 and 230.7 mg/l at the beginning and between 1.5 and 105.6 mg/L at the end of the test. The measured TOC concentrations prove that the substance was present in the test solution. The lower measured concentrations at the end of the test were most likely caused by adsorption of the test item to the algal cells or precipitation of the test item due to a reaction between the test item and the minerals in the test medium. Because the test item is a UVCB with several different components, the determination of the biological result was based on the nominal concentration.

The 72h-EC₅₀ values of potassium dichromate (K₂Cr₂O₇, CAS No. 7778-50-9) were determined in a separate reference test. The values lay within the range of the laboratory (growth rate 0.64 - 1.10 mg/L, yield 0.21 – 0.66 mg/L).

The following results for the test item Kombucha;Echa name: "Fermentation product of sucrose and Camellia sinensis (Theaceae) leaves with a variable symbiosis of bacteria and yeast, including various Acetoacteraceæ bacteria and Saccharomycetaceae yeasts" were determined:

Endpoint	NOEC	LOEC	EC10	EC50
Growth Rate	100.00 mg/L	320.00 mg/L	244.12 mg/L	1892.33 mg/L
Yield	100.00 mg/L	320.00 mg/L	205.94 mg/L	486.22 mg/L

Note: The NOEC is determined by comparing each treatment with the blank control using a hypothesis test. A statistically insignificant variation is considered as "no observed effect". In contrast, EC10 and EC50 are determined by regression analysis and read from the toxicity vs. concentration graph