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Ecotoxicological information

Toxicity to terrestrial plants

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Administrative data

Endpoint:
toxicity to terrestrial plants: short-term
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study is very well described regarding the experimental conditions and the obtained results. However, there is an important issue revealing by the analytical monitoring. Indeed, the authors reported an important drop in concentrations among the substances they tested. The precise measurements performed on catechol were not given, but this substance is include in the analysis; leaving doubt on its stability. For this reason, it is not possible to conclude on the toxicity of catechol to terrestrial plants.

Data source

Reference
Reference Type:
publication
Title:
Phytotoxicity studies with Lactuca sativa in soil and nutrient solution.
Author:
Hulzebos E.M. et al.
Year:
1993
Bibliographic source:
Environ. Toxicol. Chem., 12, 1079-1094.

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)
Deviations:
not specified
Principles of method if other than guideline:
The publication describes two tests. In the first of them, lettuce was exposed to catechol in soil under static conditions. In the second test, lettuce was exposed to a nutrient solution contaminated with catechol under semi-static conditions.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Pyrocatechol
EC Number:
204-427-5
EC Name:
Pyrocatechol
Cas Number:
120-80-9
Molecular formula:
C6H6O2
IUPAC Name:
pyrocatechol
Details on test material:
- Name of test material (as cited in study report): catechol.
- Source: commercially supplied.
- Analytical purity: Several compounds were tested in this study. The precise purity of catechol was not given. It is just known that the purity of the tested compNo further data.

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Sampling frequency: In both the soil test and the nutrient solution test, the concentrations were analyzed at the start of the tests to verify the added concentrations. Analyses were then performed at the end of the test (soil) or just before the next replacement of the test solution (nutrient solution) to detect any decrease in concentration due to degradation or volatilization.

Test substrate

Vehicle:
no
Details on preparation and application of test substrate:
SOIL TEST:
- Method of mixing into soil: Catechol was dissolved in water, added to the soil, and thoroughly mixed with an household mixer.
No further data.

NUTRIENT SOLUTION TEST:
- Method of mixing into the nutrient solution: There is no data except that the nutrient solution was treated with catechol. The solutions were renewed three times a week.
No further data.

Test organisms

Species:
Lactuca sativa
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: lettuce
- Plant family: asteracea
No further data.

Study design

Test type:
early seedling growth toxicity test
Study type:
laboratory study
Substrate type:
other: SOIL TEST: natural soil / NUTRIENT SOLUTION TEST: there was no substrate, seeds and seedlings were exposed to catechol in a nutrient solution.
Total exposure duration:
14 d
Remarks:
14 days is the exposure duration of the soil test. The nutrient solution test lasted 21 days.

Test conditions

Test temperature:
21 +/- 4°C in both tests
pH:
No data
Moisture:
SOIL TEST: 25 to 30% moisture content (80% of the water-holding capacity)
NUTRIENT SOLUTION TEST: not applicable (seeds and seedlings exposed in a liquid solution)
Details on test conditions:
--- SOIL TEST ---

TEST SYSTEM
- Testing facility: The tests were performed in climatic chambers in two institutes: the RIVM and the TNO.
- Test container (type, material, size): 0.25-L plastic trays
- Amount of soil: 400 g
- No. of seeds per container: 10
- No. of plants (retained after thinning): 5
- No. of replicates per treatment group: 2
- No. of replicates per control: 2
No further data.

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: Soil came from an orchard. There is no specification of its geographic localisation.
- % organic matter content: 1.4 for the soil sample used by TNO, 1.8 for the soil sample used by RIVM.
- % clay: 12 for the soil sample used in TNO, 24 for the soil sample used in RIVM.
- Pretreatment of soil: Soils were 4-mm-sieved before the tests started.
No further data.

NUTRIENT MEDIUM (if used)
None in the soil sample used by TNO.
K2HPO4 had to be added to the soil sample used by RIVM.

GROWTH CONDITIONS
- Photoperiod: 16:8h light:dark
- Light source: fluorescent tubes
- Light intensity and quality: 6500 lux
- Day/night temperatures: A test temperature of 21+/- 4 °C was applied during the day. It was lowered during the test (no information on the night temperature value).
- Relative humidity (%): Humidity varied between 40 and 80% during the day. It was increased during the dark period (no information on the night humidity value).
- Watering regime and schedules: Evaporation of water was compensated daily by adding demineralized water.
No further data.

ACCLIMATION PERIOD
No data.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable)
The first five germinated seedlings were required. After 7 and 14 days, shoots were harvested by cutting them off at soil level; the fresh weight of each plant was determined immediately after harvesting.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
No further data.

--- NUTRIENT SOLUTION TEST ---

TEST SYSTEM
- Testing facility: The tests were performed in climatic chambers in two institutes: the RIVM and the TNO.
- Test container (type, material, size):
* During germination: in 0.25-L plastic trays filled with perlite saturated with nutrient solution containing different catechol concentration.
* During seedlings growth: in 1-L pots filled with nutrient solution treated with different catechol concentrations.
- No. of seeds per container:
* During germination: no data.
* During seedlings growth: 5 seedlings per pot.
- No. of plants (retained after thinning): 5.
- No. of replicates per treatment group: 2.
- No. of replicates per control: 2.
No further data.

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
No soil, seeds and seedlings were exposed in nutrient solution whose the composition is not given in the prublication.

NUTRIENT MEDIUM (if used)
Seeds and seedlings were directly exposed in nutrient medium.

GROWTH CONDITIONS
- Photoperiod: 16:8h light:dark
- Light source: fluorescent tubes
- Light intensity and quality: 6500 lux
- Day/night temperatures: A test temperature of 21+/- 4 °C was applied during the day. It was lowered during the test (no information on the night temperature value).
- Relative humidity (%): Humidity varied between 40 and 80% during the day. It was increased during the dark period (no information on the night humidity value).
No further data.

ACCLIMATION PERIOD
No data.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable)
Shoots were harvested 16 and 21 days after sowing at TNO and RIVM, respectively. Fresh weight was then measured.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
No further data.
Nominal and measured concentrations:
No data, except that nominal concentrations were spaced by a factor of 3.2
Reference substance (positive control):
not specified

Results and discussion

Effect concentrationsopen allclose all
Species:
Lactuca sativa
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks on result:
other: Results of SOIL TEST
Species:
Lactuca sativa
Duration:
16 d
Dose descriptor:
EC50
Effect conc.:
5 other: mg/L nutrient solution
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Remarks on result:
other: Results of NUTRIENT SOLUTION TEST at TNO (The same result was observed following the 21-day exposure at RIVM)
Details on results:
Analytical results: The precise measurements obtained on catechol were not given in the publication. The general trend observed among the whole compounds tested was provided:

SOIL TEST:
At the beginning of the test, the analyzed concentrations were in agreement with the nominal concentrations, mostly 70 to 150 %. At the end of the test, the concentrations in soil of most phenolic compounds had dropped to a low value (<20% of the initial analyzed concentration).

NUTRIENT SOLUTION TEST:
At the beginning of the test, the analyzed concentrations of most compounds varied somewhat from 100% of the nominal concentration (60-113%). Just before renewal of the nutrient solution, in most tests the concentrations were still >50% of initial analyzed levels.

Conclusion for catechol: As the precise measurements performed on catechol were not given and knowing that concentration variations were observed during the tests, doubts remain concerning the stability of catechol. Consequently, the reliability of this study is questionable.
Reported statistics and error estimates:
The concentration at which growth was 50% of the control (EC50) was calculated by applying a logistic model according to Haanstra et al. (1985).

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
Due to the doubt remaining on the stability of catechol during the test, it is not possible to reliably conclude on its toxicity to terrestrial plants.
Executive summary:

Hulzebos et al. (1993) investigated the toxicity of catechol to the growth of Lactuca sativa seedlings. They performed two kinds of test. The first of them lasted 14 days and was performed in soil under static conditions. The second test was carried out during 16 to 21 days in nutrient solution under semi-static conditions. Catechol concentrations spaced by a factor of 3.2 were applied during both tests. Although the precise measurements performed on catechol were not given, there is some indication that the concentrations in test substances varied during the test. Consequently, due to the doubt remaining on the stability of catechol during the test, it is not possible to reliably conclude on its toxicity to terrestrial plants.

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