Registration Dossier

Diss Factsheets

Ecotoxicological information

Toxicity to terrestrial plants

Currently viewing:

Administrative data

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: Although not a guideline study, the publication is detailed enough to show good scientific practices.

Data source

Reference
Reference Type:
publication
Title:
Light and Electron Microscopy of Plant Leaf Cells after Short Term Exposure to Bromine Gas
Author:
Strauss SJ, KS Kim, LE Murray
Year:
1982
Bibliographic source:
Phytopathology, 72 (7): 793-800

Materials and methods

Principles of method if other than guideline:
Primary leaf tissue was exposed for 20 minutes to bromine gas at 1, 3, and 5 ppm, and then returned to normal environment. Visible and cellular changes were observed using light and electron microscopy.
GLP compliance:
not specified

Test material

Constituent 1
Reference substance name:
Bromine gas
IUPAC Name:
Bromine gas
Details on test material:
- Name of test material (as cited in study report): Bromine
- Physical state: Vapors from liquid bromine

Sampling and analysis

Analytical monitoring:
not specified

Test substrate

Details on preparation and application of test substrate:
- Method of application: Liquid bromine was allowed to evaporate from a ground glass weighing bottle in the 9.5 Liter desiccator used as the exposure chamber. The desiccator had a vacuum pump to circulate the bromine gas.

Test organisms

Species:
other: Vigna Unguiculata (L.) Walp. (Monarch)
Plant group:
Dicotyledonae (dicots)
Details on test organisms:
- Common name: Cowpea
- Plant family: dicotyledon
- Variety: "Monarch"

Study design

Test type:
other: observation of damage to primary leaf tissue
Study type:
laboratory study
Substrate type:
other: Plants exposed to bromine gas
Total exposure duration:
20 min
Post exposure observation period:
Tissues sampled immediately after exposure and at 24 hours after return to normal environment

Test conditions

Test temperature:
25 degrees C and atmospheric pressure
Details on test conditions:
TEST SYSTEM
- Testing facility: sunlit greenhouse during months of July and August
- Test container (type, material, size): 7.5 cm diameter clay pots
- Soil: Terralite Rediearth Peat-Lite Mix
- Fertilizer: Once with 20-20-20 Peters Soluble Fertilizer (60 gm/L) diluted 1:50
- No. of seeds per container: 1 plant per container

GROWTH CONDITIONS
- Photoperiod: Natural photoperiod for July, August in Fayetteville, Arkansas
- Light source: Natural sunlight
- Any fertilization (if used): Once with 20-20-20 Peters Soluble Fertilizer (60 gm/L) diluted 1:50


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

- Phytotoxicity rating system (if used): description of the histology and pathology of the leaf sections examined from control and treated plants

TEST CONCENTRATIONS
- Test concentrations: 1, 3, 5 ppm bromine gas generated from evaporation of liquid bromine volumes of 10, 30, and 50 uL into a desiccator of 9.5 L volume
Nominal and measured concentrations:
1, 3 or 5 ppm bromine (nominal)

Results and discussion

Effect concentrationsopen allclose all
Species:
other: Vigna unguiculata
Duration:
20 min
Dose descriptor:
other: phytopathology
Effect conc.:
ca. 5 other: ppm
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
phytotoxicity
Remarks:
irreversible damage to al cell types (electron microscopy)
Species:
other: Vigna unguiculata
Duration:
20 min
Dose descriptor:
other: phytopathology
Effect conc.:
1 other: ppm
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: loss of cell integrity and degeneration of plasmalemma, tonoplast and membranous organelles (electron microscopy)
Remarks on result:
other: Immediate post exposure samples
Species:
other: Vigna unguiculata
Duration:
20 min
Dose descriptor:
other: phytopathology
Effect conc.:
1 other: ppm
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Many adaxial cells had recovered compared to the immediate samples (electron microscopy)
Remarks on result:
other: Samples taken at 24 hours
Species:
other: Vigna unguiculata
Duration:
20 min
Dose descriptor:
other: phytopathology
Effect conc.:
3 other: ppm
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: epidermal cells had plasmolysis, four types of injury in mesophyll cells (light and electron microscopy)
Remarks on result:
other: Samples immediately after exposure
Species:
other: Vigna unguiculata
Duration:
20 min
Dose descriptor:
other: phytopathology
Effect conc.:
3 other: ppm
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Necrosis developed, with collapse and compression regardless of cell type (light microscopy)
Remarks on result:
other: Samples taken at 24 hours
Details on results:
The most visible changes in the cowpea primary leaf tissue after a 20 minute exposure to 1, 3, or 5 ppm bromine gas was the formation of circular, adaxial and abaxial surface lesions and leaf compressions. At 1 ppm, changes such as adaxial depression and anticlinal cell wall interdigitation were reversed when exposed plants were returned to normal environments. At 5 ppm, the entire population immediately became irreversibly necrotic.

Applicant's summary and conclusion

Conclusions:
A 20 minute exposure to bromine gas at concentrations of 1, 3 or 5 ppm produced formation of visible circular, adaxial and abaxial surface lesions and leaf compression. Although the degree and type of injury varied, all epidermal and mesophyll cells were affected. At 1 ppm, some cellular changes were reversed when plants were returned to normal environments, but at 5 ppm, the entire cell populations became irreversibly necrotic.
Executive summary:

Immediate and delayed (24 hours) effects of a 20 -minute exposure of cowpea (Vigna unguiculata) primary leaf tissue to 1, 3, or 5 ppm bromine gas were studied with light and electron microscopy. The formation of circular, adaxial and abaxial surface lesions an dleaf compression were the most visible changes. Major cytological modifications included cytoplasmic vacuolation, disruption of cellular membranes, plasmolysis, alteration of nucleolar structure, anticlinal cell wall interdigitation, and collapse of protoplast and/or cell wall. Although the degree and type of injury varied, all epidermal and mesophyll cells were affected by the treatments. Spongy mesophyll cells surrounded by large air spaces were more severely affected by the bromine gas than were the closely packed palisade mesophyll cells. At 1 ppm bromine, certain cellular changes such as adaxial depression and anticlinal cell wall interdigitation were reversed when the exposed plants were returned to a normal environment. At 5 ppm bromine, the entire cell population became irreversibly nectoric.