4-ethylbenzaldehyde

Long-term toxicity to fish

Additional information

Long-term toxicity (Rácz et al)

In addition to the acute toxicity test to fish, the publication by Rácz et al. also describes a long-term set up, which does not follow any specific guideline and is therefore summarized here.

Long-term effects of the test substance is determined in a research study. In this study, two groups of 25 zebrafish (Danio rerio) per treatment were exposed to nominal concentrations of 5 and 10 mg/L for 3 months under semi-static conditions. The test media were renewed every 4 days. The test concentrations were derived from the short-term toxicity test and represent a sub-acute toxicity level, below the 96-h LC10. The biomass loading rate was 0.4 - 0.5 g fish/L. The test conditions were continuously maintained. Twice every day, the behaviour of the test organisms was observed. Furthermore, each week two fish were taken from the study and prepared for histological analysis. During the study, 100% lethargy was observed, as fish did not escape capture. However, no disorientation was observed. 14 days after study initiation, histological changes in liver, skin and kidney occurred, which progressed in severity throughout the study, especially in the 10 mg/L group. Effects included change in fat droplet distribution and glycogen content in parenchyma cells in the liver, pycnotic chromatic condensations in the kidney and increase of mucin-producing cells over time in the skin. Only in the high-dose treatment, the quantitative analysis showed an increase in the degree of fatty change of the liver cells. No tumors were observed. Even though effects are observed at 5 mg/L, insufficient information is available to derive an EC10 value that can be used for risk assessment.