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

In the key study, an early life stage test with fathead minnow (Pimephales promelas) according to OECD Test Guideline 210 in compliance with GLP, the NOEC for HHCB was found to be 0.068 mg/l.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater fish:

0.068 mg/L

Additional information

An early life stage test was carried out with fathead minnow (Pimephales promelas) according to OECD Test Guideline 210 under flow-through conditions (Croudace et al. 1997). Eggs less than 24 h old were exposed to nominal concentrations ranging from 0.0125 to 0.2 mg/l (step size 2). Concentrations were measured 13 times at regular intervals during the 36-day test period. Egg hatchability was not significantly affected in any of the test concentrations. Larval survival after 32 days was not affected in concentrations of 0.068 mg/l and below. In the highest concentration of 0.140 mg/l mean larval survival was 78%. Larval growth was not affected in concentrations of 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 NOEC for HHCB from this e.l.s. fish study is 0.068 mg/l. The study was carried out according to GLP principles. The validity criteria were met. The test is valid without restrictions (Reliability 1).

In addition, a 21 -d prolonged toxicity test is available. This test was carried out with bluegill sunfish (Lepomis macrochirus) according to OECD Test Guideline 204 under 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 2). Concentrations were measured at the start, halfway through and at the end of the test period. Survival of the fish was not significantly affected up to and including 0.182 mg/l. However, at 0.182 mg/l (and above) clinical signs of irregular respiration, bottom and tail dominated swimming, loss of equilibrium and righting reflex were observed. Mortality was 10% at the next higher concentration of 0.393 mg/l and coincided with significantly reduced growth. In 0.830 mg/l, mortality reached 100% after 14 days and in 1.566 mg/l at day 2. The 21-d LC₅₀was 0.452 mg/l. The overall NOEC of the test was 0.093 mg/l as determined by the onset of clinical signs at the next higher concentration. GLP study; the validity criteria were met: control mortality < 10%. Dissolved oxygen above 60% of air saturation. Steady dose-effect relation. Reliable without restriction.

As the lowest NOEC was found in the early life stage test, this study was chosen as key study.