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Toxicity to terrestrial arthropods

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Administrative data

Endpoint:
toxicity to terrestrial arthropods: long-term
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Already evaluated by the Competent Authorities for Biocides and Existing Substance Regulations.

Data source

Reference
Reference Type:
publication
Title:
Comparison of instantaneous rate of population increase and critical-effect estimates in Folsomia candida exposed to four toxicants
Author:
Herbert, I.N., Svendsen, C., Hankard, P.K. & Spurgeon, D.J.
Year:
2004
Bibliographic source:
Ecotox. Environ. Safety 57:175-183

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
ISO 11267 (Inhibition of Reproduction of Collembola by Soil Pollutants)
Principles of method if other than guideline:
Method: other: ISO
GLP compliance:
no
Application method:
soil

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
IUCLID4 Test substance: other TS: Cu2+ as delivered as copper chloride

TS-Freetext:
The soil was contaminated with CuCl2 (supplied by
SigmaAldrich).

The concentrations tested were based on previously published
data, spanning the reported LC50 and EC50 values for soil
species that were available.

Six treatments and a control (with four replicates at each
level) were utilized and doses were spaced in geometric
series such that the penultimate dose was approximate to
estimated LCso values based on available literature data.

The test used nominal concentrations of 12.5, 50, 200, 800,
3200, and 12,800 mg/kg dry soil for copper.

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
At Tend

Test substrate

Vehicle:
no
Details on preparation and application of test substrate:
Substrate type: artificial OECD soil. pH (H2O) 6.0 ; Clay 20% ; OM 10% ; background copper concentration: 3.2 mg/kg dw ; CEC 14.5 cmol/kg

Test organisms

Test organisms (species):
Folsomia candida
Animal group:
Collembola (soil-dwelling springtail)
Details on test organisms:
F. candida individuals were obtained from Reading University. Experiments were carried out using juveniles of between 10 and 12 days old.

Study design

Study type:
laboratory study
Limit test:
no
Total exposure duration:
28 d

Test conditions

Test temperature:
20 +_ 1°C
pH (if soil or dung study):
6.0
Photoperiod and lighting:
12 h light/ 12 h dark light regime
Details on test conditions:
endpoint: instantaneous rate of population increase. Tests were performed with 10 (F. candida) juveniles per container for each treatment and using 4 replicates. 35 g soil per container. 2 mg baker's yeast was added at the start and after 14 days.
Nominal and measured concentrations:
6 added test concentrations (between 12.5 and 12800 mg Cu/kg) + 1 control

Results and discussion

Effect concentrations
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
796.8 mg/kg soil dw
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
element
Remarks:
Cu
Basis for effect:
other: rate of population increase
Remarks on result:
other: IUCLID4 note: "m" (measured/nominal)
Reported statistics and error estimates:
NOEC value was derived using a GLM aNOVA and Dunnett's test.

Any other information on results incl. tables

RS-Freetext:
Three adults (mean 0.75 per replicate) survived at the top
dose (12,800 mg/kg) in the copper experiment (Fig. 1B).

Adult survival was significantly affected by soil copper
concentration (GLM; P<0.01), but was only significantly
different in comparison with the control at a soil
concentration of 12,800 mg/kg (Dunnetts, P<0.01). The LC50
value (Table 1) was calculated to be 6840 mg/kg. A
significant effect of copper on juvenile production was
found (GLM, P<0.01), with significant reductions in
comparison with the control at concentrations of 3200 mg/kg
and higher (Dunnetts, P<0.01). The EC50juvenile value (Table
1) was calculated to be 813 mg/kg.

Calculated ri values (Fig. 2B) ranged from -0.086
(extinction) to 0.077 (in one replicate at 200 mg/kg). The
mean control ri was calculated as 0.041. Copper
significantly affected ri (GLM, P<0.01), with significant
differences found between the control and treatment ri
values at concentrations of 3200 mg/kg and higher (Dunnetts,
P<0.01). Least-squared fitting of
ri values using a logistic model gave a good agreement (R2
>0.75) between the model and the observed values (Fig. 2B).
From this regression the concentration at which ri = 0 was
calculated to be 2760 mg/kg (Table 1 and Fig. 2B).

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Good quality study. NOEC data were used for the PNEC derivation. Reliable added NOEC value was 796.8 mg/kg.
Executive summary:

In this study the sensitivity of instantaneous rate of population increase is compared to critical-effect estimates for populations exposed to four toxicants with different modes of action. Populations of the Collembolan Folsomia candida were exposed to cadmium, copper, pyrene, and chlorpyrifos in artificial soil following the standardized ISO (International Organization for Standardization, Geneva, 1999) protocol. ri values and LC50, EC50juvenile, and NOEC values are calculated for each chemical. Reliable added Cu -NOEC value for F. candida was 796.8 mg/kg and was used for the PNEC derivation.

Comparison of the relative toxocity of the four chemicals indicated that chlorpyrifos had the lowest values and was thus the most toxic, followed by pyrene, cadmium, and copper. Significant changes in ri were seen to follow closely changes in the sublethal parameter measured (juvenile production) and showed populations in decline at concentrations as low as 40% of the LC50. The study showed ri to be a good measure of population response, and the authors conclude that the statistic gives a better understanding of effects on a population than through the sole use of traditional critical-effect estimates.