o-cresol

Toxicity to terrestrial plants

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to terrestrial plants: short-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)

Deviations:

no

Principles of method if other than guideline:

Second experiments were carried out in nurtient solutions

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

analytical monitoring at test start and end of exposure and before renewal of test solution

Vehicle:

no

Details on preparation and application of test substrate:

test substance was dissolved in water

Species:

Lactuca sativa

Plant group:

Dicotyledonae (dicots)

Test type:

early seedling growth toxicity test

Study type:

laboratory study

Substrate type:

other: soilo and solution (and perlite as an unreactive substrate)

Limit test:

no

Remarks:

14 d in soil, 21 in nutrient solution

Test temperature:

21 +/- 4 °C

pH:

7.5

Moisture:

Soil experiment: 25 to 30 % moisture content (80% of the water-holding capacity)

Details on test conditions:

16:8 h light:dark 6500 lx fluorescent tubes

Nominal and measured concentrations:

analytical monitoring at start and end of test

Species:

Lactuca sativa

Duration:

7 d

Dose descriptor:

other: EC50 soil

Effect conc.:

67 mg/kg soil dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth

Remarks on result:

other: 95% C.I.: 52-86

Species:

Lactuca sativa

Duration:

14 d

Dose descriptor:

other: EC50 soil

Effect conc.:

> 100 mg/kg soil dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth

Species:

Lactuca sativa

Duration:

21 d

Dose descriptor:

other: EC50 nutrient solution

Effect conc.:

23 other: mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth

Remarks on result:

other: 95% C.I.: (16-31)

For most of the examined phenols (including o-cresol) applied concentrations 
dropped but remained larger than 50 % of the nominal values.

Validity criteria fulfilled:

not specified

Conclusions:

The toxicity of o-cresol to lettuce seedlings (Lactuca sativa) was determined according to OECD Guideline 208 in soil. The EC50 was 67 mg/kg soil d.w. after 7 d, >100 mg/kg soil d.w. after 14 d. The highest effect concentration (EC50 >100 mg/kg) was normalised to an OC content of 3.4% according to TGD (EU 2003), resulting in a corrected EC50 of >242 mg/kg.

Executive summary:

The short-term toxicity of o-cresol to lettuce (Lactuca sativa) was examined by Hulzebos (1993). The test compound was incorporated into soil according to OECD-guideline 208. The organic matter of 2 soil types used was given as 1.4 to 1.8 %. Lettuce seed was sown and the weight of the crops (above-ground biomass) was measured after 7 and 14 days. After an exposure period of 14 days, a nominal EC50 of >100 mg/kg soil (dry weight) was obtained. According to TGD (EU 2003), the effect concentration (EC50 >100 mg/kg) is corrected for a standard soil with a content of organic matter of 3.4 % resulting in a corrected EC50 of >242 mg/kg. The authors stated that “at the end of the test, the concentrations of most phenols in soil had dropped to a low value (<20% of the initial analysed concentrations)”.

Reference 2

Endpoint:

toxicity to terrestrial plants: long-term

Type of information:

other: expert judgement on long-term toxicity

Adequacy of study:

other information

Reliability:

other: expert judgement on long-term toxicity

Justification for type of information:

A long-term toxicity test on plants is not relevant according to column 2 of Annex X of Regulation EC 1907/2006, as the risk assessment does not indicate the need to investigate further the effects of the substance on terrestrial organisms (please refer to the Chemical Safety Report). The risk to soil organisms exposed to the substance is acceptable based on the PNECsoil calculated using the Equilibrium Partitioning Method and does not need to be refined using long-term tests.

Principles of method if other than guideline:

not applicable; expert judgement on long-term toxicity

A long-term toxicity test on plants is not relevant according to column 2 of Annex X of Regulation EC 1907/2006, as the risk assessment does not indicate the need to investigate further the effects of the substance on terrestrial organisms (please refer to the Chemical Safety Report). The risk to soil organisms exposed to the substance is acceptable based on the PNECsoil calculated using the Equilibrium Partitioning Method and does not need to be refined using long-term tests.

Executive summary:

A long-term toxicity test on plants is not relevant according to column 2 of Annex X of Regulation EC 1907/2006, as the risk assessment does not indicate the need to investigate further the effects of the substance on terrestrial organisms (please refer to the Chemical Safety Report). The risk to soil organisms exposed to the substance is acceptable based on the PNECsoil calculated using the Equilibrium Partitioning Method and does not need to be refined using long-term tests.

Description of key information

The toxicity of o-cresol to lettuce seedlings (Lactuca sativa) was determined according to OECD Guideline 208 in soil. The EC50 was  >100 mg/kg soil d.w. after 14 d. The effect concentration was normalised to an OC content of 3.4% , resulting in a corrected EC50 of >242 mg/kg.
However, in case of only one test result is available, the risk assessment should be performed both on this test result and on the basis of the outcome of the aquatic toxicity data. Therefore the equilibrium partitioning method with the PNEC for aquatic organisms is also taken into account for assessment.

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:

242 mg/kg soil dw

Additional information

Several studies of toxicity of o-cresol towards terrestrial plants were found in the literature.

The scope of the terrestrial effects assessment under the adopted REACH regulation is restricted to soil organisms in a narrow sense and does not actually include adverse effects on soil functions that are only indirectly linked to the biota in soils.

Some tests were designed assessing the influence of o-cresol on germination and growth on moist filter paper or agar treated with the substance. As no soil was used in the tests standardisation of soil effect data to given soil parameters is not possible. Further, converting the results to an appropriate dimension is not applicable. Therefore the results should not be used for the hazard assessment.

Using soil, short-term toxicity of o-cresol to lettuce (Lactuca sativa) was examined. The test compound was incorporated into soil according to OECD-guideline 208. The organic matter of 2 soil types used was given as 1.4 to 1.8 %. Lettuce seed was sown and the weight of the crops (above-ground biomass) was measured after 7 and 14 days. After an exposure period of 14 days, a nominal EC50 of >100 mg/kg soil (dry weight) was obtained. According to TGD (EU 2003), the effect concentration (EC50 >100 mg/kg) is corrected for a standard soil with a content of organic matter of 3.4 % resulting in a corrected EC50 of >242 mg/kg. The authors stated that “at the end of the test, the concentrations of most phenols in soil had dropped to a low value (< 20% of the initial analysed concentrations)".