Chlorhexidine dihydrochloride

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Version / remarks:

cited as 92/69/EEC (C.2.) (1992)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Infracor Chemistry Services

Analytical monitoring:

yes

Details on sampling:

The analyses were carried out by measurement of dissolved organic carbon.
The test item concentration range for the testing was below the detection limit of 1 mg TOC/L. Beside this, no suitable substance specific method exist at this time to analyse the test item concentrations in this very low range.
Due to these facts, only the test item concentrations of the stock solution and one of the additional test concentration directly above the detection limit (= additional stability control) could be determined after 0 and 48 h by TOC analysis. These measurements were used to assess the stability of the test item in this test system. The results of the stock solution analysis were used for the calculation of the nominal amount of the test item in the test vials.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna Straus
- Strain: clone 5
- Source: Animals bred at the testing facility, originally derived from Dr. N. Caspers, Bayer AG, Leverkusen, Germany
- Age at study initiation: Neonates < 24 h old
- Method of breeding: For breeding the females were maintained in M4-medium in 1L beakers.
At two to three day intervals, the exuviae were syphoned off, the water was changed and the offspring
removed from the breeding vessels.
At regular intervals of approximately 4 weeks, offspring was isolated from the vessels. They served as
a basis for further breeding.
Females are separated from the offspring 24 hours before the start of the test. The litter produced
overnight was used for the test.
The culture conditions ensure parthenogenetic reproduction.
- Feeding during test: no

ACCLIMATION
- Food type: Desmodesmus (formerly Scenedesmus) subspicatus, unicellular green algae
- Amount: Amount of food was such that the amount added was consumed by the animals
- Frequency: Daily

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

14°dH = 250 mg CaCO3/L

Test temperature:

20 +/- 1°C

pH:

7.8 - 8.1

Dissolved oxygen:

7.7 - 8.2 mg/L

Nominal and measured concentrations:

0.0077, 0.013, 0.023, 0.040, 0.070, 0.12 mg/L (concentration are based on the main product)
The analytical concentrations of the stock solution and the additional stability control after 48 h did not deviate by more than 20% from the freshly prepared solutions. It can be concluded that the test substance concentration was stable during the whole exposure time. Therefore, the nominal concentration of the stock solution was used to calculate the test item concentrations in the test batches.

Details on test conditions:

TEST SYSTEM
- Test vessel: 10 mL
- Type: open. Test substance is not volatile
- No. of organisms per vessel: 5 +/- 1
- No. of vessels per concentration (replicates): 4
- Biomass loading rate: Approx. 2 mL per test organisms

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Synthetic fresh water
- Ca/Mg ratio: 4 : 1
- Culture medium different from test medium: Yes, Elendt M4 medium as described in OECD Guideline 202

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: Complete darkness

EFFECT PARAMETERS MEASURED : Immobility. Sampling at 24 and 48 hours

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

0.04 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.055 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: range of EC50: 0.04 - 0.07 mg/L

Duration:

48 h

Dose descriptor:

EC100

Effect conc.:

0.12 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mobility

Results with reference substance (positive control):

- Results with reference substance valid? yes
EC50 (24 h) > 1 mg/L (nominal concentrations)
EC100 (24 h) = 2 mg/L

Reported statistics and error estimates:

EC50 -values were determined graphically

Validity criteria fulfilled:

yes

Conclusions:

The test results indicate that Chlorhexidine dihydrochloride is acutely very toxic towards daphnia. The 48h-EC50 was determined to be 0.055 mg a.s./L.

Description of key information

An GLP acute toxicty study with Daphnia magna according to the OECD 202 guideline was performed.

The test results indicate that Chlorhexidine dihydrochloride is acutely very toxic towards daphnia. The 48h-EC50 was determined to be 0.055 mg a.s./L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.055 mg/L