1,4:5,8-Dimethanonaphthalene, 2-ethylidene-1,2,3,4,4a,5,8,8a-octahydro-

Toxicity to aquatic algae and cyanobacteria

Description of key information

Pseudokirchneriella subcapitata: EC50 values could not be calculated but are considered to be >53.0 µg/L.  The "no observed effect concentration" (NOEC) in terms of growth rate and yield = 53.0 µg/L.  NOEC in terms of area under the growth curve = 29.4 µg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

53 µg/L

Additional information

An algal inhibition study was conducted (Huntingdon Life Sciences, 2013, study number VHJ0016) to assess the effect of ETD on aquatic algae. The study was performed according to EC test method C3 and OECD test guideline 201, and in compliance with GLP.

Five concentrations up to the measured limit of solubility (0.16 mg/L, 160µg/L) prepared using THF-based stock solutions were assessed (THF was present in the final solutions at 100 µL/L). At the end of the 72 hour test period the concentration of ETD in test solutions was found to be significantly lower than the nominal starting concentrations; concentrations in the test vessels were lower than concentrations measured in concurrent vessels without algal cells so it is considered that the presence of algal cells had affected the stability of ETD in solution.

There was no statistically significant inhibition of Pseudokirchneriella subcapitata in terms of average specific growth rate or yield after 72 hours of exposure to ETD up to a mean measured concentration of 53.0 µg/L. In terms of area under the growth curve, a statistically significant level of inhibition was observed at 53.0 µg/L but this may not be of biological importance as inhibition was reduced by less than 10%.

Consequently, EC50 values could not be calculated but are considered to be >53.0 µg/L.

The “no observed effect concentration” (NOEC) for average specific growth rate and yield was 53.0 µg/L. In terms of area under the growth curve, the NOEC was 29.4 µg/L.

ECOSAR (EPI Suite ECOSAR, v1), a computer model, was used to estimate the toxicity to Algae of ETD. ETD was classified as a Neutral Organic compound, and the partition coefficient was used to calculate the acute and chronic LD₅₀values.

The acute LD₅₀to Algae was estimated to be 0.343 mg/L. It was noted that this value was above the measured water solubility for ETD, and so ETD may not be soluble enough to measure the predicted effect.