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Toxicity to terrestrial plants

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Endpoint:
toxicity to terrestrial plants: long-term
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint:
toxicity to terrestrial plants: short-term
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP Guideline study but eight deviations from protocol are listed and no analytical monitoring reported.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test)
GLP compliance:
yes
Analytical monitoring:
not specified
Vehicle:
no
Details on preparation and application of test substrate:
An appropriate amount of coarse sand was coated with MDI (MDI added to acetone and mixed with sand which was subsequently dried for 2 days in furne-cupboard) and mixed with agricultural soil (ratio 1:1) to reach a concentration of 1000 mg MDI per kg of dry soil. Demineralized water added (ratio 1:1 on weight basis).

Artificial soil: mixture of natural soil from an orchard in Heerewaarden (The Netherlands) and coarse sand (grain size 50 to 1 000 µm) + 1.66 g K2HPO4; final pH of range: 5.0 - 7.5
Species:
Avena sativa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
Oat: CEBECO, Roterdam (The Netherlands)
Species:
Lactuca sativa
Plant group:
Monocotyledonae (monocots)
Details on test organisms:
Lettuce: Rijk Zwaan (De Lier, The Netherlands)
Test type:
seedling emergence toxicity test
Study type:
laboratory study
Substrate type:
artificial soil
Limit test:
yes
Total exposure duration:
14 d
Post exposure observation period:
Test parameter: emergence, mortality, appearance and growth (weight).
Test temperature:
19°C (dark)
25 °C (light)
pH:
6.3 (at start)
6.4 (at end)
Moisture:
50%
Details on test conditions:
- Number of replicates, seeds per replicate: 10 seeds per cup containers, five replicates for both test containers and controls (one replicate for pH measurement). Five seeds removed from each cup after emergence.
- photoperiod: 16 hours
- light intensity: 6 000- 8 000 lux.
- control: yes (with acetone)
Nominal and measured concentrations:
1000 mg per kg of dry soil.
Species:
Avena 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
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
Species:
Avena sativa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
seedling emergence
Species:
Lactuca sativa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
seedling emergence
Species:
Avena sativa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Species:
Lactuca sativa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth
Species:
Avena sativa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: survival
Species:
Lactuca sativa
Duration:
14 d
Dose descriptor:
NOEC
Effect conc.:
>= 1 000 mg/kg soil dw
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: survival
Details on results:
No parameter significantly (5%) affected by test substance.

Description of key information

A 14d-EC50 of >1000 mg/kg soil (d.w.) was obtained for the test substance with the monocotyleous plants Avena sativa and Lactuca sativa according to OECD 208. Because MDI reacts rapidly with water to form predominantly insoluble and inert polyurea (Yakabe et al., 1994), no long-term toxicity tests with plants have been performed.

Key value for chemical safety assessment

Short-term EC50 or LC50 for terrestrial plants:
1 000 mg/kg soil dw

Additional information

The test substance is covered by the category approach of methylenediphenyl diisocyanates (MDI). Hence, data of the category substances can be used to cover this endpoint. A short-term toxicity study (van der Hoeven et al, 1992), carried out according to OECD 208, is available for PMDI for the monocotyleous plants Avena sativa and Lactuca sativa. In this limit test, a 14d-EC50 of >1000 mg/kg soil (d.w.) was obtained in artificial soil. The endpoint was based on emergence, mortality, appearance and growth (weight) of the plants.

No long-term terrestrial toxicity tests on terrestrial plants are available for the test substance. Because MDI reacts rapidly with water to form predominantly insoluble and inert polyurea (Yakabe et al., 1994), long-term toxicity tests with plants are not appropriate for the derivation of PNEC values.