Reaction mass of endo-2-methyl-exo-3-methyl-exo-2-[(endo-3-methylbicyclo[2.2.1]hept-endo-2-yl)methyl]bicyclo[2.2.1]heptane and endo-2-methyl-exo-3-methyl-exo-2-[(endo-2-methylbicyclo[2.2.1]hept-endo-3-yl)methyl]bicyclo[2.2.1]heptane and endo-2-methyl-exo-3-methyl-exo-2-[(exo-3-methylbicyclo[2.2.1]hept-exo-2-yl)methyl]bicyclo[2.2.1]heptane and endo-2-methyl-exo-3-methyl-exo-2-[(exo-2-methylbicyclo[2.2.1]hept-exo-3-yl)methyl]bicyclo[2.2.1]heptane

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Please refer to attached justification for read across.

Reason / purpose for cross-reference:

read-across source

Vehicle:

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.21 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Remarks:

estimated from limit of quantification

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.21 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Remarks:

estimated from limit of quantification

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 0.21 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Remarks:

estimated from limit of quantification

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

> 0.21 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Remarks:

estimated from limit of quantification

Basis for effect:

biomass

Details on results:

In unfiltered samples of test cultures, the measured concentrations of T-12 ranged from 84.4 mg/L at the start to 79.2 mg/L after 72 hours. The concentrations of T-12 in filtered samples were below the limit of accurate quantification of the available analytical method (<0.210 mg/L) on both occasions of analysis. Although the concentration of dissolved T-12 to which the algae were exposed could not be identified, a condition of maximum attainable exposure is considered to have been employed.

Cell numbers were counted daily to monitor growth. The test results are expressed in terms of the area under the growth curve and growth rate. At a nominal concentration of 100 mg/L, the reductions in these values during the study were, at most, only 2% compared to the control cultures.
Consequently, neither the 72-hour median effect concentrations (EbC50 and E,C50) nor the no observed effect concentration (NOEC) were identified but must be greater than limit of quantification of the test substance in test medium.

Results with reference substance (positive control):

The results of the most recent laboratory reference test using potassium dichromate indicated that its 72-hour EbC50 to Selenastrum capricornutum was 0.52 mg/L; this was within the range typically obtained in this laboratory (0.3 to 1 mg/L).

Reported statistics and error estimates:

None required

Nominal T-12 concentration	Cell densities (x10^4cells/ml)
	24 hours	48 hours	72 hours
Control                               R1                               R2                               R3                               R4                               R5                               R6                             Mean	9.12 7.62 6.28 7.21 7.05 6.33   7.27	33.9 24.1 28.0 28.5 26.5 26.6   27.9	113 67.4 137 137 125 121   117
100 mg/ml                               R1                               R2                               R3                               R4                               R5                               R6                             Mean	10.5 9.14 9.32 9.92 9.85 9.10   9.64	37.4 33.4 24.8 31.7 31.0 29.6   31.3	94.6 104 113 87.0 116 117   105

R1 – R6 Replicates 1 -6

Validity criteria fulfilled:

yes

Remarks:

Although the concentration of dissolved T-12 to which the algae were exposed could not be identified, a condition of maximum attainable exposure is considered to have been employed.

Conclusions:

T-12 was not found to be inhibitory to Selenastrum capricornutum when dispersed in algal nutrient medium at concentrations greatly in excess of its limit of aqueous solubility.

Description of key information

The test substance, T-12, an analogue of the registered substance T-13h, was not found to be inhibitory to Selenastrum capricornutum when dispersed in algal nutrient medium at concentrations greatly in excess of its limit of aqueous solubility.

Additional information

The toxicity of T-12 to aquatic algae was determined by HLS, 1998, Report No.: IDK0064. The study was conducted in accordance with OECD Method 201 and EU method C3 and was considered reliable.