Symclosene

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed to GLP and guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

GLP compliance:

yes

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

TEST ORGANISM
- Common name: Earthworm
- Source: Blades Biological, Cowden, Edenbridge, Kent, UK
- Age at test initiation: 2 months old
- Weight at test initiation: See table 2


ACCLIMATION
- Acclimation period: The test organisms were transferred into artificial soil (without the test material) approximately 24 hours prior to the start of the test
- Acclimation conditions (same as test or not): Yes

Study type:

laboratory study

Substrate type:

artificial soil

Total exposure duration:

14 d

Test temperature:

See table 3 for individual data

pH:

5.6 - 6.1 at study initiation
5.6 - 5.9 at study termination

Moisture:

The moisture content of the soil in the definitive test was 29 to 30% of dry weight of basic substrate on day 0 and 26 to 27% on day 14.

Details on test conditions:

TEST SYSTEM
- Test container: 1 L glass beaker
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 6
- No. of replicates per control: 4



SOURCE AND PROPERTIES OF SUBSTRATE (artificial soil)
- % Industrial quartz sand: 70% w/w
- % Kaolinite clay: 20% w/w
- % Sphagnum moss peat: 10% w/w
- moisture content: 29% to 30% of dry weight of basic on day 0 and 26% to 27% on day 14
- pH: Adjusted to 6.0 ± 0.5 by addition of calcium carbonate



OTHER TEST CONDITIONS
- Light intensity: 520 - 575 Lux, continuous


EFFECT PARAMETERS MEASURED : Mortalities observed at 7 and 14 days exposure


VEHICLE CONTROL PERFORMED: no


TEST CONCENTRATIONS
- Range finding study
- Test concentrations: Nominal concentrations of 10, 100 and 1000 mg test material/kg dry soil
- Results used to determine the conditions for the definitive study: Based on the results of the range finder a limit test was conducted at a concentration of 1000 mg test material/kg

Nominal and measured concentrations:

1000 mg test material / kg of dry soil (equivalent to 756 mg cyanuric acid/kg of dry soil)

Reference substance (positive control):

yes

Remarks:

Chloroacetamide

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: Equivalent to >756 mg/kg cyanuric acid

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:

mortality

Remarks on result:

other: Equivalent to 756 mg/kg cyanuric acid

Results with reference substance (positive control):

- Relevant effect levels:
LC50 (7 days) = 21 mg/kg (95% c.l. = 19 – 22 mg/kg)
LC50 (14 days) = 20 mg/kg (95% c.l. = 18 – 22 mg/kg)
NOEC = 10 mg/kg

Reported statistics and error estimates:

Statistical analysis of the earthworm weight data was performed using Bartlett’s test for homogeneity of variance (Sokal and Rolf 1981) and a Students t-test. All statistical analyses were performed using the SAS computer software package (SAS 1999-2001).

Table 1: Cumulative mortality data for definitive test

Nominal concentration (mg test material/kg dry soil)	Cumulative mortality (initial population: 10)		% Mortality
Control	Day 7	Day 14	Day 7	Day 14
R1	0	0	0	0
R2	0	0	0	0
R3	0	0	0	0
R4	0	0	0	0
1000
R1	0	0	0	0
R2	0	1*	0	10
R3	0	0	0	0
R4	0	0	0	0
R5	0	0	0	0
R6	0	0	0	0

R1 - R6 =Replicates 1 to 6

* Mortality considered to be due to natural causes rater than a toxic effect

Table 2: Mean earthworm weights in the definitive test

Nominal concentration (mg test material/kg dry soil)	Mean earthworm weight (g)
	Day 0		Day 14
Control	Mean	SD	Mean	SD
R1	0.38	0.06	0.32	0.07
R2	0.43	0.08	0.38	0.07
R3	0.43	0.09	0.38	0.09
R4	0.40	0.08	0.37	0.08
1000
R1	0.41	0.06	0.40	0.06
R2	0.36	0.07	0.34	0.06
R3	0.45	0.08	0.42	0.07
R4	0.42	0.08	0.39	0.06
R5	0.43	0.06	0.39	0.06
R6	0.39	0.05	0.39	0.05

SD = standard deviation

Table 3: Room temperature records

Day	Room temperature (°C)
0	21.9
1	21.9
2	21.6
3	20.9
4	20.2
5	21.4
6	21.9
7	20.6
8	20.7
9	22.0
10	22.1
11	22.0
12	21.6
13	22.0
14	21.8

There were no significant mortalities or sub-lethal effects of exposure in 60 earthworms exposed to a test concentration of 1000 mg test material/kg dry soil for a period of 14 days. A single observed mortality was considered due to natural causes and not a toxic effect.  It was considered to be unnecessary and unrealistic to test at concentrations in excess of 1000 mg test material/kg dry soil.  The definitive test showed the highest test concentration resulting in 0% mortality to be greater than or equal to 1000 mg test material/kg dry soil and the lowest test concentration resulting in 100% mortality to be greater than 1000 mg test material/kg dry soil.  There were no observed sub-lethal effects of exposure of Eisenia foetida to the test material.

Validity criteria fulfilled:

yes

Conclusions:

Cyanuric acid is not harmful to earthworms

Description of key information

The chlorinated isocyanurates are unstable in the environment, because the free available chlorine is rapidly reduced.  CYA, or its salt, is the stable degradation product. Therefore, CYA, or its sodium salt, is the substance of interest for the terrestrial compartment is cyanuric acid. An acute earthworm toxicity test according to OECD Guideline 207 with the monosodium salt of cyanuric acid is available

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

756 mg/kg soil dw

Additional information

A study was performed to assess the acute toxicity of the monosodium salt of cyanuric acid to earthworms(Eisenia foetida) in an artificial soil (Goodband 2007). 60 earthworms (six replicates of 10 worms) were exposed to a single concentration of 1000 mg test material/kg of dry soil for a period of 14 days. The number of mortalities was determined after 7 and 14 days exposure. The 14 day LC50 for the test material based on nominal test concentrations was > 1000mg test material/kg dry soil (equivalent to 756 mg cyanuric acid/kg dry soil). The NOEC was 1000 mg test material/kg dry soil (equivalent to 756 mg cyanuric acid/kg dry soil).