Pyrocatechol

Endpoint summary

Additional information

Short-term toxicity to fish

Seven studies were available, and one of them (Geiger et al., 1990) was selected as key study. In this 96-hour acute toxicity study, Pimephales promelas were exposed to catechol at nominal concentrations of 0, 8, 10, 12.5, 15.6 and 19.5 mg/L under flow through conditions, and mortality was recorded. The 96-h LC50 was 9.22 mg/L. Catechol is toxic for Pimephales promelas under the tested conditions. The toxicity study is classified as acceptable and satisfies the guideline requirements for acute fish toxicity study.

 

Two other reliable studies gave results in the same range as the key study and were considered supporting studies. The other available studies had a reliability 3 or 4.

 

Long-term toxicity to fish

No data on long-term toxicity to fish is available.

 

Short-term toxicity to aquatic invertebrates

A study which was done according to GLP and following the OECD Guideline is available (Seeland-Fremer et al., 2014). The study was done in closed systems and analytical measurements were performed and a Klimisch rating of 1 was assigned to this study. This study resulted in an EC50 of 1.09 mg/l after 48 hours of exposure and based on geometric mean measured concentrations.

 

Two other studies with a reliability 2 according to Klimisch are available (Devillers et al., 1987; Rhône-Poulenc, 1977). They were well described and followed the French standardised method NF T90301. The 24-hour EC50 values were 1.67 mg/L and 2.1 mg/L, respectively, which means that the results were in agreement with the study of Seeland-Fremer et al. (2014).

 

Long-term toxicity to aquatic invertebrates

The only chronic data available on invertebrates was performed on a non standardized species using a non standardized method. It is thus not possible to conclude on the long-term toxicity of catechol to aquatic invertebrates.

 

Toxicity to algae

Only one study (Majnusz, 1994) was reliable, with a score of 2 according to Klimisch. It was selected as a key study, because it was well described and conducted similarly to the OECD guideline 201. In this study, the toxicity of the test item catechol was evaluated in the algal strain Chlorella vulgaris during 96 hours.The main criterion measured was the EC50, a statistically derived concentration resulting in 50% reduction of the average specific growth rate. The 96-hour EC50 was 22 mg/L. There is no indication allowing to know whether the validity criteria were fulfilled. Based on these results, catechol is considered as harmful to algae.

 

Other studies were not well described, or not conducted according to recognized guidelines and were all scored as reliability 3.

 

Toxicity to micro-organisms

Most data were available on isolated species. Two of these studies were scored as reliability 2 according to Klimisch and selected as key studies. Based on growth inhibition of Tetrahymena pyriformis, 48h-EC50 values of 57.14 mg/L (Schultz, 1996) and 19.58 mg/L (Schultz, 1990) were reported. In view of the chemical safety assessment, the lowest value was retained.

 

The only reliable data available on mixed inoculum concerned anaerobic sludge, and was of reliability 2. A 3d-EC50 = 1814 mg/L, based on methane production inhibition, was reported in this study (Sierra-Alvarez, 1989).

 

The other available data contain few details. They were performed using species which are either not among those recommended by the guidelines, or considered of a low relevance when assessing the risk for micro-organisms from STP. Furthermore, some of the methods applied are not enough standardised to conclude on the toxicity of catechol to micro-organisms.

 Based on these results, catechol could be harmful to some of the tested microorganisms.