1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylindeno[5,6-c]pyran

Long-term toxicity to fish

Description of key information

The NOEC for Pimephales promelas (fathead minnow) according to OECDTG 210 under flow through conditions was 0.068 mg/l based on mean measured concentrations.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

NOEC

Effect concentration:

0.068 mg/L

Additional information

Three long term fish toxicity studies are available. The study by Croudace et al. (1997) is considered key as it presents the lowest NOEC. Two other studies are presented as supporting studies, which are not included in the study records.

Key study: Croudace et al. (1997), freshwater, Fathead minnow

An early life stage (ELS) test was carried out with fathead minnow (Pimephales promelas) according to OECD Test Guideline 210 under GLP and flow-through conditions. Eggs less than 24 h old were exposed to nominal concentrations ranging from 0.0125 to 0.2 mg/l (step size factor 2). Concentrations were measured 13 times at regular intervals during the 36-day test period.

Results: Egg hatchability was not significantly affected in any of the test concentrations: effect value > 0.140 mg/l. A 32d-NOEC for larval survival was > 0.068 mg/l (at 0.140 mg/l; larval survival was 78%). The NOEC for Larval growth was 0.068 mg/l (-11% weight, not statistically significant; at 0.140 mg/l, mean length and weight were reduced by 20 and 54%, respectively, as compared to the solvent control. Larvae surviving in the highest concentration (0.140 mg/l) were recorded to be generally smaller, less well developed and appeared less active, exhibiting some erratic swimming behaviour and loss of balance. Therefore, the overall NOEC for long-term fish is 0.068 mg/l.

 

Supporting study: Wüthrich (1996), freshwater, Bluegill sunfish, RCC 380711

A 21-d prolonged toxicity test was carried out with bluegill sunfish (Lepomis macro­chirus) according to OECD TG 204 under GLP and flow-through conditions. Test parameters included fish growth (weight and length). The fish weights at the start of the experiment varied between 1.4 and 1.6 g.  Nominal concentrations ranged from 0.125 to 2.0 mg/l (step size factor 2). Concentrations were measured at the start, halfway through and at the end of the test period.

Results: The validity criteria were met: control mortality < 10%; the dissolved oxygen was above 60% of air saturation and; steady dose-effect relation. Study is considered Kl 2. LC50 for mortality is 0.452 mg/l. Mortality was 100% at 1.566 mg/l after 2-days and at 0.8390 after 14 days. Mortality (10%) and growth were affected at 0.393 mg/l and coincided with significantly reduced growth. NOECsurvival is 0.182 mg/l. At this 182 mg/l (and above) clinical signs of irregular respiration, bottom and tail dominated swimming, loss of equilibrium and righting reflex were observed, resulting in a NOEC of 0.093 mg/l for clinical signs.

 

The study below is not relevant for the risk assessment: Kl. 3. 

Chen et al. (2011), freshwater, Goldfish, Environmental Pollution 162: 91-97: Oxidative stress biomarkers were used to assess the toxic effects of simulated runoff containing the substance on Goldfish (Carassius auratus). Fish were exposed to concentrations equal to 0.15, 1.5, 15, 75 and 150 μg/l of the substance for 21 days. The activity of antioxidant enzymes in the liver of C. auratus were analyzed after 7-,14- and 21-day exposure. The results showed that the activity of antioxidant enzymes and the content of malondialdehyde increased significantly when exposed to simulated urban runoff containing the substance alone or in a mixture with Cd and returned back to baseline after 21 days exposure. 

As this study only indicated potential oxidative stress, data is insufficient to measure long term toxicity to fish, no concentration response for the measured endpoint (non-regulatory) and would require further validation to extrapolate from in vitro to in vivo data, the study is therefore disregarded.