3,5,5-trimethylcyclohex-2-enone

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No standard test procedure, but in accordance with generally accepted scientific standards and described in sufficient detail.

Qualifier:

according to guideline

Principles of method if other than guideline:

Method: other: see Test Conditions

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Isophorone was dispensed directly from the bottle

Test organisms (species):

other: other algae: Champia parvula (marine red macroalgae)

Details on test organisms:

TEST ORGANISMS
- Strain: Champia parvula (C. Agardh) Harvey
- Laboratory culture: inhouse
- Method of cultivation: 1000 ml Erlenmeyer flasks containing 800 ml of  culture medium; culture medium made from natural seawater to which additional nutrients (as below, but 4/4 portions of vitamin solution)  were added after filtration and autoclave treatment
- Pretreatment: stock cultures started weekly, halved weekly with change  of media, ready after 3 weeks

Test type:

semi-static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

14 d

Test temperature:

22 - 24 °C

Salinity:

28-30 o/oo

Nominal and measured concentrations:

29.9, 49.84, 83.07, 138,45 and 230.75 ug/L

Details on test conditions:

TEST SYSTEM
- Concentrations: dilution factor 0.6; maximum determined in screening  test
- 5 female branch tips (2-3 mm) plus one  male branch, visibly producing spermatia, per test vessel
- Renewal of test solution: days 7 and 11
- Exposure vessel type: 500 ml Erlenmeyer flask filled 80 %, screw-capped
- 5 concentrations with a dilution factor of 0.6
- Number of replicates: 2
- Intensity of irradiation: 75 uE/(m2 s)
- Photoperiod: 16 h light / 8 h dark
- Aeration: replaced by 150 mg/l sodium bicarbonate

GROWTH/TEST MEDIUM 
- the following substances were added per liter of filtered seawater:    
37.4 mg NaNO3,  2.5 mg NaH2PO4 x H2O, 10.4 ug Fe (as FeCl2),  1/4 portion of:   (0.24 ug vitamin B12, 0.24 ug biotin, 50 ug thiamine x HCl)

EFFECT PARAMETERS MEASURED
- females were examined for the presence of cystocarps (evidence of sexual reproduction)
- tetrasporophytes (vegetative growth) were counted as well
- both parameters were recorded as final dry weight

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

49.8 mg/L

Nominal / measured:

nominal

Basis for effect:

other: vegetative growth and sexual reproduction of females

Duration:

14 d

Dose descriptor:

LOEC

Effect conc.:

83.07 mg/L

Nominal / measured:

nominal

Basis for effect:

other: vegetative growth and sexual reproduction of females

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

29.9 mg/L

Nominal / measured:

nominal

Basis for effect:

other: vegetative growth and reproduction of tetrasporophytes

Duration:

14 d

Dose descriptor:

LOEC

Effect conc.:

49.8 mg/L

Nominal / measured:

nominal

Basis for effect:

other: vegetative growth and sexual reproduction of tetrasporophytes

Duration:

14 d

Dose descriptor:

other: MATC

Effect conc.:

38.6 mg/L

Nominal / measured:

nominal

Basis for effect:

other: vegetative growth and sexual reproduction of tetrasporophytes

Details on results:

MATC (maximum acceptable toxicant concentration): was calculated as the geometric mean of the lowest concentration that resulted in a significant
difference from the control and the next lowest concentration tested.

LOECs (lowest concentration that is statistically different from the control)

for various endpoints:
- vegetative growth (dry weight): 83.07 mg/l
- sexual reproduction (cystocarps): 83.07 mg/l
- presence of tetrasporangia: 49.84 mg/l
NOEC = 60% of LOEC

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study in accordance with generally accepted scientific standards and described in sufficient detail

Qualifier:

according to guideline

Principles of method if other than guideline:

Method: other: Growth Inhibition Test according to a proposal of the Umweltbundesamt, Germany

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

STOCK AND TEST SOLUTION AND THEIR PREPARATION
- Concentration of vehicle/ solvent: 10 g test substance/l

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISMS
- Strain: CHODAT (86.81 SAG)
- Source/supplier: Origin: Institut fuer Wasser-, Boden- und Lufthygiene,  Berlin, further bred inhouse
- Laboratory culture: From a stock culture, a preculture was established three days before begin of test. Test cultures were inoculated from the latter.
- Method of cultivation: Erlenmeyer flasks on tables exposed to light
- Initial cell concentration: ca. 20,000 cells/ml

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Nominal and measured concentrations:

0 / 125 / 200 / 350 / 600 / 1000 mg/l (nominal concentrations)

Details on test conditions:

TEST SYSTEM
- The test cultures were established from a 3 day old pre-culture via inoculation
- cell density: 20,000/ml
- Number of replicates: 3

DILUTION WATER
- Aeration: yes, sterile
- illumination: yes

EFFECT PARAMETERS MEASURED
- turbidity; method not specified

Reference substance (positive control):

not specified

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

64 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

475 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC90

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: not calculable

Details on results:

STATISTICAL RESULTS
- comparison of areas under growth curves, probit transformation, probit analysis (Cavalli-Sforza 1972)

Turbidity after 0 / 24 / 48 / 72 h:
 Control:  0.5 / 1.8 / 4.4 / 8.9
 125 mg/l: 0.5 / 1.9 / 3.5 / 6.4
 200 mg/l: 0.5 / 1.9 / 3.5 / 5.8
 350 mg/l: 0.5 / 2.1 / 2.5 / 4.1
 600 mg/l: 0.5 / 2.1 / 1.9 / 1.9
1000 mg/l: 0.5 / 1.8 / 1.6 / 2.2

Executive summary:

In a 72 hour toxicity study, the cultures of Scenedesmus subspicatus were exposed to the test item at nominal concentrations of 125; 200; 350; 600 and 1000  mg/L under static conditions according to a method proposed by UBA (Feb. 1984).

The EC10 and EC50 values based on biomass were 64 mg/L and 475 mg/L, respectively.

The study was assessed as "reliable with restrictions".

Description of key information

The growth inhibition of the substance on the freshwater alga Scenedesmus subspicatus was tested by Huels AG (1996d) according to a test procedure similar to OECD- Guideline 201. The algae were exposed to 5 concentrations between 125 and 1000 mg/l and one control.
Thursby et al. (1985) tested the effects of the test item on the marine red alga Champia parvula. Various biological endpoints, namely vegetative growth, formation of tetrasporangia (asexual reproduction) and production of cystocarps (sexual reproduction) were observed.

Key value for chemical safety assessment

EC50 for freshwater algae:

475 mg/L

EC10 or NOEC for freshwater algae:

64 mg/L

EC10 or NOEC for marine water algae:

29.9 mg/L

Additional information

Based on nominal concentrations, the 72h-EC10 value (based on biomass development) was determined as 64 mg/l and the EC50 as 475 mg/l (Huels AG, 1996).

In the second study (Thursby et al, 1985), the most sensitive endpoints after a 14 -day exposure period were found to be growth of tetrasporophytes and number of tetrasporangia exhibiting a LOEC of 49.8 mg/l. The next lowest test concentration was 60 % of this value, thus the NOEC is calculated to be 29.9 mg/l.