Zeolite, synthetic, crystalline, non fibrous, silica and titanium based

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1991-08

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP guideline study; no analytical monitoring was performed in the study Further, the test medium was not modified as recommended in the OECD guideline to take into consideration that zeolites have strong effects on the availability of nutrients or minerals. For strongly absorbing substances like zeolites, the actual OECD guideline proposes a modification of the test medium in offering a nutrient-rich medium.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Zeolite, cuboidal, crystalline, synthetic, non-fibrous

IUPAC Name:

Zeolite, cuboidal, crystalline, synthetic, non-fibrous

Details on test material:

- Name of test material (as cited in study report): Wessalith P
- Related CAS number: 1318-02-1
- Chemical name: Natrium-Aluminiumsilikat
- Framework: monoclinic
- Analytical purity: 79,8%

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

As the test substance contained insoluble matter, water accomodated fractions and their filtrate were tested.
To adjust the desired concentrations, test material was directly weighed in algal medium, stirred for one hour and filtered (Whatman GF/C glass microfibre filter, d=4.7 mm, the first 200 mL of the filtrate discarded) prior to test.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

-strain: SAG 86.81
- source: Institute for Plant Physiology, University of Göttingen, Germany

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test conditions

Hardness:

no data

Test temperature:

23+/-1°C

pH:

Initial pH was 8.9, it increased with algal density to 8.6 - 10.6 after 4 days.

Dissolved oxygen:

no data

Nominal and measured concentrations:

Following concentrations were tested: 0, 2.9, 10.5, 38, 103 and 328 mg/L.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

18 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Unfiltered dispersion, particle counting

Effect concentrations 2

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

34 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Unfiltered dispersion, fluorescence measurements

Effect concentrations 3

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks on result:

other: Unfiltered dispersions

Effect concentrations 4

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

34 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Unfiltered dispersion, particle counting

Effect concentrations 5

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

45 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: Unfiltered dispersion, fluorescence measurements

Effect concentrations 6

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 328 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

eluate

Basis for effect:

growth rate

Remarks on result:

other: Filtered solutions

Effect concentrations 7

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

> 328 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

eluate

Basis for effect:

biomass

Remarks on result:

other: Filtered solutions

Effect concentrations 8

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

eluate

Remarks on result:

other: Filtered solutions

Any other information on results incl. tables

Reported data relate to unfiltered suspension, endpoint growth yield, measured by particle counting.

Summary of all results (range between tested concentrations):
I)   Unfiltered dispersion, particle counting
              growth yield       area under growth curve
                                        (=biomass)
     EC10     4.9                  5.7 (2.9-10.5)
     EC50    18   (10-32)         34   (10.5-38)
     EC90    66                  130   (105-328)
II)  Unfiltered dispersion, fluorescence measurement
           growth yield       area under growth curve
                                        (=biomass)
     EC10    11                   12 (10.5-38)
     EC50    34  (28-52)          45 (38-103)
     EC90    84                   200 (105-328)

III) Filtered solution, particle counting
           growth rate        area under growth curve
                                        (=biomass)
     EC10   >328                    77 (38-103)
     EC50   >328                    >328
     EC90   >328                    >328

Note: There is a typo in table 1 of the report; growth rate for filtered solutions should read 0.072 instead of 0.72. The results refer to nominal concentrations of the test substance.
By visual comparison of the measured and the calculated growth curves of algal suspensions exposed to the test substance with those of the algal controls, the NOEC of the test item was estimated to be 38 mg/L (filtered test substance) and 10 mg/L (unfiltered test substance).

Filtered test substance solutions appeared to be much less toxic than unfiltered ones. This is explained by leaching of toxic components from particles during the test with unfiltered samples. However, turbid test solutions also result in reduced light supply, and to an increased binding of nutrients by the test substance.
Microscopic examination of the cells showed that algal cells in the unfiltered 10E3 mg/L solutions were coagulated with test substance particles at the end of the test.