Phenol

Long-term toxicity to aquatic invertebrates

Description of key information

Reliable study results are available from 7 long-term studies with Daphnia magna or Ceriodaphnia dubia.  The NOEC or EC10 values of the seven studies were in the range between 0.05 and 2.38 mg phenol/L. The EC10 of 0.46 mg phenol/L, obtained in a 16 day study for growth of D. magna under semi-static conditions, was selected as key information.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.46 mg/L

Additional information

Data on long term toxicity of phenol on aquatic invertebrates is presented in EU RAR (2006) in Section 3.2.1 (Aquatic compartment (incl. Sediment), page 36ff). It is stated that the lowest long-term effect value was found forDaphnia magnaby Deneer et al. (1988) for growth reduction as test parameter. Although this parameter is not a standardised endpoint the EC10-value of 0.46 mg/L will be used as long-term effect value for aquatic invertebrates.

Reliable study results are available from 7 long-term studies withDaphnia magnaorCeriodaphnia dubia. The tests were conducted under flow-through or semi-static conditions and the exposure concentrations were analytically verified in the flow-through study (Tisler & Zagorc-Koncan, 1999) and the semi-static studies of Oris et al. (1991) and SLOVNAT (2009). In the other semi-static studies the phenol concentrations are regarded as stable, since Colgan et al. (1982) and Lewis et al. (1983) demonstrated the stability of phenol under semi-static conditions. The NOEC or EC10 values of the six studies were comparable ranging between 0.46 and 2.38 mg/L.

The most reliable sensitive endpoint was the EC10 of 0.46 mg/L, based on nominal concentrations, obtained in a 16 day study withDaphnia magnaunder semi-static conditions with a 2 or 3 day renewal period (Deneer et al., 1988) according to the Dutch Standard Organisation NEN 6502 (1980). Test parameters were inhibition of length increase and reproduction of the daphnids. The most sensitive parameter was growth. As growth reduction will generally result in a lowered reproductive output, this endpoint is of high relevance. The measured EC10 of 2.38 mg/L for survival of adults and reproduction obtained in a 21 day flow-through study fulfilling the validity criteria of the OECD guideline (1982) performed by Tilser & Zagorc-Koncan (1999) are in the same order of magnitude like the EC10 of Deneer et al. (1988) and confirms their findings.

In the study of SLOVNAFT (2009), the long-term toxicity of phenol to Daphnia magna was investigated. The GLP-study was conducted according to OECD Guideline 211 (Daphnia magna Reproduction Test) for 21 d under semi-static conditions. The stability of the test solutions was investigated over a period of 5 days via TOC analysis. After 5 d 92.1% of the initial test substance concentration was found. Therefore the effect values refer to nominal concentrations. The 21 d NOEC, EC10, and EC50 based on reproduction were determined to be <0.1, 0.05, and 0.48 mg/L nominal, respectively. This study is regarded as valid with some restrictions: the extrapolated EC10 is below the lowest applied test substance concentration; toxicity results determined for the reference substance are reported to be considerably below values in comparable tests, which may point to an extraordinary sensitivity of the used daphnia strain. Therefore, this EC10 is not regarded as key result for long-term toxicity to aquatic invertebrates.