Phenol

Toxicity to terrestrial plants

Description of key information

One seedling emergence and growth test with Lactuca sative in soil, one test on agar with the same plant species  and four root elongation tests (Panicum miliaceum, Cucumis sativus, Lactuca sativa, and Sinapis alba) in aqueous solution were performed. Due to the most realistic exposition the test with soil was considered as key study. The test was performed according to test guideline OECD 208. Information concerning GLP was not  provided. The data are reported in the literature. The EC50 (14 d) for growth (fresh biomass) was calculated as 79 mg/kg soil dw.  Considering a standard content of organic matter of 3.4 %, an EC50 of 149 mg/kg is calculated.
For all studies no chemical analyses were performed. In one test, however, the stability of test solution was investigated over a period of 5 days via TOC analysis. After 5 d 92.1% of the initial test substance concentration was found.

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:

79 mg/kg soil dw

Additional information

The data on effects of phenol on terrestrial soil organisms is presented in EU RAR (2006) in Section 3.2.3 (Terrestrial compartment, page 44ff).

Just one EC50 value for phenol in soil with one plant species is available. According to the guidelines for a comprehensive assessment several test species including monocotyledone and dicotyledone plants have to be investigated. Although this demand is not fulfilled for the test in soil several plant species were tested in aqueous medium. The same plant species (Latuca sativa) as well as two further species (Panicum miliaceum,Cucumis sativus) were tested in aqueous medium. The EC50 for Latuca sativa (EC50: 130 mg/L; 95 % C.L. 108 - 180) was comparable to the effects for Panicum miliaceum (EC50: 120 mg/L; 95 % C.L. 65 - 180). The sensitivity of both plants was higher compared to the sensitivity of the third plant (Cucumis sativus: EC50: 220 mg/L; 95 % C.L. 180 - 300).

Now a further study finished recently (2009) is available. The toxicity of phenol to Sinapis alba was investigated in a study conducted according to the national standard method STN 83 8303 (Slovakia; filter paper test) and the root growth after 72 h determined. In the frame of the study the stability of test solution 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 concentrions. A 72 h IC50>48 mg/L nominal was determined.

Furthermore, with Latuca sativa and Panicum miliaceum the demand of testing a dicotyledone and a monocotyledone plant species is fulfilled.

In the test guideline OECD 208 (published 2006) it is the first time that chemical analyses are demanded for ecotoxicological tests with terrestrial species. According to the guideline only the stock solution has to be analysed. Due to the chemical structure hydrolysis in water is not expected.

Therefore, the result of one plant test in soil without chemical analyses is considered to be sufficient.