Salicylic acid

Toxicity to aquatic plants other than algae

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

Test material information

Constituent 1

Reference substance name:

Salicylic acid

EC Number:

200-712-3

EC Name:

Salicylic acid

Cas Number:

69-72-7

Molecular formula:

C7H6O3

IUPAC Name:

2-hydroxybenzoic acid

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