Santicizer 278®

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:

22-26 March 1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP status not known, available as unpublished report, predates OECD study guidelines but otherwise acceptable for assessment. There was no information test solution preparation or observational data on the test substance behaviour which from tests on similar substances indicates that globules formed during the study. Therefore this study is used but major reservations.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Principles of method if other than guideline:

US EPA Algal Assay Procedure: Bottle Test. 1971.

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Not applicable

Analytical monitoring:

not specified

Details on sampling:

No data

Vehicle:

no

Details on test solutions:

Concentrations for the definitive test were based on the results of a 96-hour range-finding test. Test concentrations were prepared by adding appropriate weighed amounts of test material directly to each flask. Concentrations are reported as mg of test material per litre of algal growth medium or ppm.

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Obtained from the USEPA's Environmental Research Laboratory, Corvallis, Oregon. Maintained in stock culture at BMRL.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

none reported

Hardness:

no data reported

Test temperature:

24°C ±1°C

pH:

ranged from 7.2 to 7.4

Dissolved oxygen:

no data reported

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal. 3 replicates for each of the 3 concentrations (360, 600 and 1000 mg/l), plus 3 replicates for the control.

Details on test conditions:

125 ml flask. '~20,000 cells per ml. ~4000 lux.

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 other: ppm

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Key result

Duration:

96 h

Dose descriptor:

EC10

Effect conc.:

>= 360 - <= 600 other: ppm

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Details on results:

After 96 hours of exposure, decrease of in vivo chlorophyll α was from 22% in cultures exposed to 360 and 600 ppm to 36% in those exposed to 1000 ppm. Decrease of cell numbers was from 9% in cultures exposed to 360 ppm to 21% in those exposed to 1000 ppm.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Probit analysis.

Nominal				%	chg		% chg
concentration	pH			Chlor	alpha		Cell no.
mg/l;ppm	0 h	96 h	24 h	48 h	72 h	96 h	96 h
Control	7.2	7.4	---	---	---	---	---
360	7.2	7.3	-7	-17	-36	-22	-9
600	7.2	7.3	-13	-27	-40	-22	-12
1000	7.2	7.2	-9	-26	-47	-36	-21

Conclusions:

The estimated 24-, 48-, 72-, and 96-hour EC50s were >1000 ppm. The 96-hour EC50 based on cell number decrease was also >1000 ppm. The EC10 (cell number) can be estimated as being in the range of 360 to 600 ppm. The table of results shows some effects but concentrations were far in excess of the water solubility of the substance. It is therefore concluded that Santicizer 278 is non-toxic to algae.

Executive summary:

This laboratory study was conducted before current OECD guidelines came into effect, although it was conducted in accordance with U.S. guidelines of the time (1979) and is considered adequate for assessment. It is considered reliable with restrictions. The estimated 24-, 48-, 72-, and 96-hour EC50s were >1000 ppm.  The 96-hour EC50 based on cell number decrease was also >1000 ppm. The EC10 (cell number) can be estimated as being in the range of 360 to 600 ppm.  The table of results shows some effects but concentrations were far in excess of the water solubility of the substance. It is therefore concluded that Santicizer 278 is non-toxic to algae.

Description of key information

The 96-hour EC50 based on both cell number decrease and growth rate was >1000 mg/l.  The EC10 (cell number) can be estimated as being in the range of 360 to 600 ppm. This exceeds the solubility of the test compound (0.0015 mg/l at 25°C) and it is therefore concluded that Santicizer 278 is non-toxic to algae.