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Ecotoxicological information

Toxicity to aquatic plants other than algae

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Administrative data

Endpoint:
toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
other information
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The method mainly follows the OECD guideline requirements with deviations (no reference substances, four concentrations tested). GLP and purity of the substance were not mentioned, and there is no analytical monitoring of the substance. But analysis of the results consider the potential pH effect on the toxicity.

Data source

Reference
Reference Type:
publication
Title:
Fate and effects of salicylic acid compounds in freshwater systems.
Author:
Wang WH and Lay JP
Year:
1989
Bibliographic source:
Ecotoxicology and Environmental Safety 17 : 308-316

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
These test cycles were repeated six times.
Exposure time : 7 days.
EC0, EC50, and EC100 were determined for salicylic acid and
for salicylic acid + fulvic acid (10 mg/L).
EC0 and EC10 were determined for Na salicylate and Na
salicylate + fulvic acid (10 mg/L).
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
no data

Sampling and analysis

Analytical monitoring:
not specified

Test solutions

Vehicle:
not specified
Details on test solutions:
no data

Test organisms

Test organisms (species):
Lemna minor
Details on test organisms:
TEST ORGANISM
- Common name: duckweed
- culturing conditions: laboratory conditions
- culture medium: specific nutrient solution
no more data

Study design

Test type:
static
Water media type:
freshwater
Total exposure duration:
7 d
Post exposure observation period:
no data

Test conditions

Hardness:
no data
Test temperature:
20°C
pH:
no data
Dissolved oxygen:
no data
Salinity:
no data
Nominal and measured concentrations:
nominal concentrations tested: 0, 15, 30, 60, and 120 mg/L
Details on test conditions:
TEST SYSTEM
- Incubation chamber used: yes/no
- Test vessel: 2 L beakers filled with 200mL maximum of nutrient solution
- No. of colonies per vessel: 10 plants per vessel
- No. of fronds per colony: one-leaf stage plants
- No. of replicates : 3 replicates per concentrations and test cycles were repeated 6 times

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 12h light : 12 h dark
- Light intensity and quality: 115 µE/m²

TEST CONCENTRATION
-spacing factor : 2
- nominal concentrations tested : 0, 15, 30, 60, and 120 mg/L

EFFECT PARAMETERS MEASURED
- Determination of biomass:
_ dry weight,
_ chlorophyll contents (extraction with alcohol 95% in darkness for 24 h)
_ number of leaves per test vessel
Reference substance (positive control):
not specified

Results and discussion

Effect concentrations
Duration:
7 d
Dose descriptor:
EC50
Effect conc.:
60 - 120 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: dry weight, number of leaves and chlorophyll contents
Details on results:
see freetext
Reported statistics and error estimates:
no data

Any other information on results incl. tables

At 60 and 120 mg/l of salicylic acid reduced the final leaf number, the dry weight and the chlorophyll contents of L. minor (see table 1 below).

Chlorophyll contents in Lemna tissues and in water are negatively correlated.

The highest dose caused a rapid yellowing of leaves.

Table 1: Effect of salicylic acid on the growth, biomass and chlorophyll contents of L. minor. Values expressed as percentage of controls after 7 days exposure.

Nominal concentration of salicylic acid (mg/L)

 

 No. of leaves

 

 biomass (dry weight)

 

 Chlorophyll content

 

 Tissue

 water

 15

 94*

100 

102 

160 

 30

96 

90 

100 

180 

 60

90* 

75* 

75* 

220* 

 120

20* 

15* 

3* 

* data significantly different from controls.

It was suggested in the article that additional toxic effect on the plants are likely at a pH below 5.

table 2 : pH values at different concentrations in salicylic acid and sodium salicylate

 concentration in mg/L

 0

15

30

60 

120 

 pH in salicylic acid solution

 6.74

6.60 

6.42 

5.92 

3.66 

 pH in sodium salicylate solution

 6.89

6.92 

7.00 

7.14 

7.38 

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Remarks:
not applicable no guideline followed and not enough data to assess validity criteria
Conclusions:
In the conditions tested, salicylic acid showed a slight effect on growth of the aquatic plant Lemna minor.
However, complementary results with sodium salicylate which does not lower the pH as much as salicylic acid showed no toxicity directly linked to the substance. This toxicity of salicylic acid therefore might be due to a physical effect (acid).
Executive summary:

In a 7 days acute toxicity test, single-leaf plants of Lemna minor were exposed to salicylic acid at nominal concentrations of 0, 15, 30, 60 and 120 mg/L.

The study did not followed a guideline but seems to be scientifically well performed.

Growth inhibition was recorded via biopmass parameters (dry weight, number of leaves and chlorophyll content inside tissues and in water).

These parameters and were significantly different from control between 60 and 120 mg/L, therefore the The 7 -d EC50 is between 60 and 120 mg/L of salicylic acid.

Yellowing was only observed at the highest concentration tested.

In the test conditions, salicylic acid is considered as harmful to algae according to Directive 67/548/EEC criteria.

Authors also indicate that salicylic acid and sodium salicylate are of a lower toxicity to aquatic plants in a concentration range up to 50 mg per liter and could be ranked into class 1 of chemicals with a low hazard potential (Geyer et al., 1985).

Considering the effect on solution pH of salicylic acid it is therefore relevant to consider that the toxic effect observed in this study is related to a physical effect (acid) and as suggested by authors, to consider salicylic acid as a substance with low hazard potential.

The authors have not followed any guideline and no information is given for GLP, analytical monitoring of the substance, purity of the substance, test conditions. But, it seems that the method mainly follows OECD guidelines with deviations (no reference substances testing, four concentrations tested). And analysis of the results is reliable by considering the potential pH effect on the toxicity.

Therefore this toxicity study is considered as reliable with restrictions