Ledum palustre, ext.

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

other: bibliography

Adequacy of study:

weight of evidence

Study period:

1986 to 1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Ledum palustre mother tincture is a UVCB and natural complex substance, and is assesed through constituents approach taking into account one the main constituent : ethanol present at 65%.

Qualifier:

according to guideline

Guideline:

other: Growth rate measured as chlorophyll content and biomass accumulation at concentrations of 0.05% (500 mg/l) and higher (range 500 to 10,000 mg/l).

Principles of method if other than guideline:

Growth rate measured as chlorophyll content and biomass accumulation at concentrations of 0.05% (500 mg/l) and higher (range 500 to 10,000 mg/l).

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

not specified

Details on test solutions:

Ethanol was tested three times at each concentration (0, 0.05, 0.1, 0.3, 0.5 and 1%).

Test organisms (species):

Chlorella vulgaris

Details on test organisms:

Cultivation method: Cultures were grown in Algal Assay Procedure (1971) medium in 500 ml flasks containing 250 ml algal suspension.
Cells were not removed from medium prior to measurement; cell density not given.
Controls consisted of algal suspensions without solvent in each experiment.

Test type:

not specified

Water media type:

not specified

Total exposure duration:

4 d

Remarks on exposure duration:

This duration is different than standard duration (72h or 96h) but this test was chosen because Chlorella vulgaris is the most sensitive species.

Hardness:

15 mg/l NaHCO3 and 12 mg/l K2HPO4

Test temperature:

21 +/- 1 deg C with continuous illumination at 100 microE/m^2-sec.

pH:

not described

Dissolved oxygen:

not described

Salinity:

not described

Conductivity:

not described

Nominal and measured concentrations:

Test design: Ethanol was tested three times at each concentration (0, 0.05, 0.1, 0.3, 0.5 and 1%).
Method of calculating mean measured concentrations: Only nominal concentrations were used.

Details on test conditions:

Cells removed before measurement: cells were not removed.
Biological observations:
+Cell density at each flask/each measuring point: Not given.

Reference substance (positive control):

not specified

Key result

Duration:

4 d

Dose descriptor:

EC50

Effect conc.:

1 000 mg/L

Nominal / measured:

meas. (not specified)

Basis for effect:

growth rate

Remarks on result:

other: Growth was inhibited 54% at an ethanol concentration of 1000 mg/l, the value approximating the EC50.Growth inhibition was 37% at 500 mg/l. Growth was significantly inhibited (p=0.05) at all concentrations of ethanol.

Details on results:

Growth was inhibited 48% at an ethanol concentration of 10,000 mg/l; this approximates the ErC50.

Validity criteria fulfilled:

not specified

Conclusions:

Growth was inhibited 48% at an ethanol concentration of 10,000 mg/l; this approximates the ErC50.

Executive summary:

Using CPL regulation criteria (1272/2008 regulation) for classification, ethanol is not toxic or harmful for algae.

Description of key information

DATA FOR ETHANOL

Two robust studies of 96-hr duration each give NOEC values of <500 mg/l for the growth rate end point in Chlorella vulgaris and Selenastrum capricornutum (El Jay, 1996). Corresponding EC 50 values were 1,000 mg/l and 10,000 mg/l. Another study conducted to a high standard in Chlamydomonas eugametos yielded a 48-hr EC 50  of 2000mg/l (Hess, 1980) and a study on Chlorella pyrenoidosa and a variety of algal species all gave EC 50 values greater than 1,000 mg/l (Cowgill, 1989; Hess, 1980; Stratton, 1987; Stratton, 1988). 

One study of 5 days duration in Skeletonema costatum gave a NOEC in the range 3,240 to 5,400 mg/l based on cell count and corresponding EC 50 values of 10,943-11,619mg/l). The authors (Cowgill, 1989) remark that using EPA criteria, ethanol can be judged non-toxic by this test and that ethanol was used as a carbon source stimulating growth of the alga before inhibition began.

All results are shown in the table 12 of UNEP publication (see below) :

SPECIES	TEST PERIOD (in days)	EC50 (mg/L)
Chlorella vulgaris	4	1000
Lemna gibba	7	4432
Lemna minor	7	3690
Selenastrum capricornatum	4	10000
Chlamydomonas eugametos	2	2000
Skeletonema costatum	4	10943 - 11619
Chlorella pyrenoidosa	10	1180

DATA FOR LEDUM PALUSTRE MOTHER TINCTURE

With a dilution in water (ca 33%), EC 50 value of tincture mother can be estimated as EC50 of ethanol in a wort case so it can can be estimated greater than 1000 mg/l.

Using CPL regulation criteria (1272/2008 regulation) for classification, ledum palustre mother tincture is not toxic or harmful for algae.