Hyoscine

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006-07-26 to 2007-01-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The read-across justification is included as attachmant to Iuclid section 13.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

ANALYSIS OF ALGAL GROWTH:Small volumes of the test media and the control (1.0 mL) were taken out of all test flasks after 24, 48 and 72 hours of exposure, and were not replaced.In addition, after 72 hours exposure, a sample was taken from the control and from the test concentration 100 mg/L. The shape and size of the algal cells were examined microscopically in these samples.
ANALYSIS OF TEST ITEM:For the analysis of the actual test item concentrations the following samples were taken:Just before the start of the test: duplicate samples from each test medium (without algae) and duplicate samples from the control (without algae).After 72 hours (stability samples): duplicate samples from each test medium (with algae) and duplicate samples from the control (with algae).For the 72-hour stability samples, the contents of the test flasks of each treatment were poured together.All samples were deep-frozen (at about -20°C) immediately after sampling. Based on pre-experiments (without GLP) for investigation of the storage stability, the test item is stable in the test water under these storage conditions.

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)- Method: The test stock solution was prepared by dissolving the test substance in the culture medium (as indicated in the OECD guideline)- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): The test medium of the highest test concentration of nominal 100 mg/L was prepared by dissolving 49.0 mg of the test item completely in 500 ml of test water using intense stirring for 10 minutes at room temperature. This intensively mixed test medium was used in a series of dilutions to prepare the test media with lower item concentrations. The test media were prepared just before the start of the test.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Species: Scenedesmus subspicatus CHODAT, Strain No.86.81 SAG
- Source: Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, D-37073 Göttingen, Germany)
- Age at study initiation (mean and range, SD): cells were taken from an exponentially growing pre-culture, which was set up 3 days prior to the test under the same conditions as in the test
- Culture density: 10,000 algal cells per mL of test medium

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Calculated water hardness of the test water: 0.24 mmol/L (=24 mg/L as CaCO3)

Test temperature:

22 to 23°C

pH:

pH was checked at start (pH 8.1-8.5) and end (8.2-8.4) of the exposure

Nominal and measured concentrations:

Nominal: 4.6, 10, 22, 46 and 100 mg/L Measured: 90% of the nominal value (100 mg/L) at the start of the testMeasured: 72% of the nominal value (100 mg/L) at the end of test

Details on test conditions:

The test was started (0 hours) by inoculation of 10000 algal cells per mL of test medium. These cells were taken from an exponentially growing pre-culture, which was set up three days prior to the test under the same conditions as in test. After the test vessels were set to 22-23°C in the test apparatus, the start was initiated. Cell density was checked after 24, 48 and 72 hours of exposure. To do so, an aliquot was taken off each solution and counted with an electronic particle counter (Coulter Counter, Model ZM).

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 50 mL
- No. of organisms per vessel: 15 mL algal suspension
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6


TEST MEDIUM / WATER PARAMETERS
- Total hardness (converted to CaCO3): 250 mg/L (2.5 mmol/L)
- Alkalinity: 0.9 mmol/L
- Water: Analytical grade salts and additives will be dissolved in purified water to obtain reconstituted M7 water.
- pH = 7.9

OTHER TEST CONDITIONS
- Photoperiod: continuously illumination
- Light intensity: about 7800 Lux (by fluorescent tubes (Philips TLD 36W/840), installed about 35 cm above the test flasks)
- Test temperature: 22-23°C (in a temperature controlled water bath)
- Initial pH 8.1 to 8.5

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- The inhibition of algal growth was determined from the mean values of counted algal cell densities.
- The LOEC and the NOEC were determined directly from the counted algal cell densities. A statistical evaluation of the algal cell densities was not necessary since the mean algal cell density in all test media up to the highest concentration was at all counting dates equal or slightly higher compared to the control.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

80 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

The 72-hours LOEC and the 72-hours EC10 and EC50 for the yield and growth rate could not be quantified due to the absence of a toxic effect of Hyoscine butylbromide at the tested concentrations. Accordingly, these parameters were clearly higher than the highest test concentration of mean measured 80 mg/L (nominal 100 mg/L), but concentrations above 100 mg/L have not been tested, according to EU Commission Directive 92/69/EEC.

Algal cell density during the 72 -hour test period

Nominal test item     concentration (mg/L)	Flask No.	Density of algal cells (cell number * 10000/mL) after
		24 h		48 h		72 h
Control	1	3.6	3.9	12.5	12.2	63.0	63.5
	2	5.0	4.6	16.5	16.8	79.7	78.7
	3	4.8	4.6	16.8	16.9	80.6	81.4
	4	4.7	4.6	16.1	16.8	84.2	84.5
	5	5.4	5.1	14.0	14.2	85.1	86.9
	6	5.2	4.9	16.8	16.6	85.5	84.5
	m	4.70		15.52		79.80
	s	0.52		1.86		8.51
	n	6		6		6
4.6	1	4.3	4.7	15.1	14.2	82.1	83.5
	2	4.5	4.5	16.4	16.1	84.6	85.7
	3	5.2	5.0	16.2	16.1	86.2	87.0
	m	4.70		15.68		84.85
	s	0.35		0.90		1.92
	n	3		3		3
10	1	4.8	4.7	15.9	16.1	86.0	84.3
	2	5.1	4.9	16.7	16.9	86.9	85.6
	3	5.0	4.8	16.0	15.5	85.2	86.6
	m	4.88		16.18		85.77
	s	0.13		0.55		0.56
	n	3		3		3
22	1	3.8	4.2	14.7	15.5	70.1	69.7
	2	4.5	4.8	16.3	16.3	78.9	77.4
	3	4.9	4.8	16.7	16.0	82.9	82.8
	m	4.50		15.92		76.97
	s	0.44		0.71		6.56
	n	3		3		3
46	1	4.9	5.0	16.9	16.6	76.8	77.2
	2	4.3	4.8	15.5	14.6	80.2	81.1
	3	5.5	5.0	18.4	18.2	89.8	88.4
	m	4.92		16.70		82.25
	s	0.35		1.63		6.21
	n	3		3		3
100	1	4.8	4.7	18.2	17.8	84.9	81.7
	2	4.9	4.6	17.4	16.8	79.9	80.4
	3	4.6	4.9	17.2	17.1	79.2	78.1
	m	4.75		17.42		80.70
	s	0.13		0.51		2.37
	n	3		3		3

Validity criteria fulfilled:

yes

Conclusions:

The influence of the test item Hyoscine butylbromide on the growth of the green algal species Scenedesmus subspicatus was investigated in a 72-hour static test according to the EU Commission Directive 92/69/EEC, C.3, 1992, and the OECD Guideline no. 201. The test item clearly had no inhibitory effect on the growth of Scenedesmus subspicatus during the test period of 72 hours at the mean measured test concentration of 80 mg/L (nominal 100 mg/L). This test concentration was therefore determined as the 72-hour NOEC.

Description of key information

The read-across substance Hyoscine butylbromide was assessed for its toxicological potential to algae in a static algal inhibition test over 72 hours according to OECD 201. Under this test conditions a NOEC of 80 mg/L (nominal 100 mg/L) was determined. A 72-hour LOEC and a 72-hour EC10 and EC50 for the yield and growth rate could not be quantified due to the absence of a toxic effect of Hyoscine butylbromide at the tested concentrations.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

80 mg/L