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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Method similar to OECD guideline with some restrictions: 14 d tested
Principles of method if other than guideline:
Daphnia magna (ca. 12 hours old) were exposed to different concentrations of 1,2-dichlorobenzene for about 14 days until at least three broods were obtained. The animals in groups of 10 were kept in 500 mL closed bottles, completely filled with IRCHA standard water added with the test material, 8 mg/L dried wtight Selenastrum capricornutum and 200 mg/L wet weight commercial yeast. The bottles (3 replicates per test group) were kept in a climatic room at 20 °C with a 16 h light photoperiod. The solutions were changed every other day, at the same time the numbers of dead and newborn animals were observed and removed. Samples of water were taken for the gas-chromatographic analysis of the test concentration after 48 hours. During the test, the loss of compound did not exceed 15% of the initial value. Repeated measurements of pH and O2 in the test solutions did not show fluctuation higher than 10%. Fertility data were elaborated according to Winner and Farrel (1976) to obtain instantaneous growth rates, while multiple controntations in the variance analysis were adopted to find the concentrations which gave differences of r significant compared with the control.
Winner RW and Farrel MP (1976): J. Fish. Res. Board Canada, 33: 1685-1691
GLP compliance:
not specified
Analytical monitoring:
yes
Test organisms (species):
Daphnia magna
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Duration:
14 d
Dose descriptor:
other: EC16
Effect conc.:
0.37 mg/L
Nominal / measured:
not specified
Conc. based on:
not specified
Basis for effect:
reproduction
Remarks on result:
other: The EC16 is viewed as being the NOEC
Duration:
14 d
Dose descriptor:
EC50
Effect conc.:
0.55 mg/L
Nominal / measured:
not specified
Conc. based on:
not specified
Basis for effect:
reproduction
Duration:
14 d
Dose descriptor:
LOEC
Effect conc.:
0.4 mg/L
Nominal / measured:
not specified
Conc. based on:
not specified
Basis for effect:
reproduction
Details on results:
The EC16 is reported as no effect concentration due to the accepted hypothesis that a reproductive impairment ranging from 10 to 20% could be considered in the range of natural variability.
Conclusions:
A 14 day reproduction toxicity test with Daphnia magna was performed under semi-static conditions with a daily renewal of the test solution. Reported endpoints were EC50 (14 d) of 0.55 mg/L 1,2 -dichlorobenzene, EC16 (14 d) of 0.37 mg/L and LOEC (14 d) of 0.4 mg/L. The EC16 is reported as NOEC due to the accepted hypothesis that a reproductive impairment ranging from 10 to 20% could be considered in the range of natural variability.
Executive summary:

Calamari et al (1983).

A 14 day reproduction toxicity test with Daphnia magna was performed under semi-static conditions with a daily renewal of the test solution. Reported endpoints were EC50 (14 d) of 0.55 mg/L 1,2 -dichlorobenzene, EC16 (14 d) of 0.37 mg/L and LOEC (14 d) of 0.4 mg/L. The EC16 is reported as NOEC due to the accepted hypothesis that a reproductive impairment ranging from 10 to 20% could be considered in the range of natural variability.

Description of key information

A 14 day reproduction toxicity test with Daphnia magna was performed under semi-static conditions with a daily renewal of the test solution (Calamari et al, 1983). Reported endpoints were EC50 (14 d) of 0.55 mg/L, EC16 (14 d) of 0.37 mg/L and LOEC (14 d) of 0.4 mg/L.  The EC16 was found to be the lowest endpoint for the long-term toxicity of the test substance to aquatic invertebrates. This value is reported as a NOEC due to the accepted hypothesis that a reproductive impairment ranging from 10 to 20% could be considered in the range of natural variability. 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
0.37 mg/L

Additional information

A 14 day reproduction toxicity test with Daphnia magna was performed under semi-static conditions with a daily renewal of the test solution (Calamari et al, 1983). Reported endpoints were EC50 (14 d) of 0.55 mg/L, EC16 (14 d) of 0.37 mg/L and LOEC (14 d) of 0.4 mg/L. The EC16 was found to be the lowest endpoint for the long-term toxicity of the test substance to aquatic invertebrates. This value is reported as a NOEC due to the accepted hypothesis that a reproductive impairment ranging from 10 to 20% could be considered in the range of natural variability.

In another publication (Kühn et al, 1989), the long-term effect of 1,2-dichlorobenzene on Daphnia magna was investigated in a 21 day toxicity test according to the provisional procedure proposed by the Federal Environmental Agency (1984). The NOEC was determined at 0.63 mg/L.

Although Kühn et al (1989) investigated the toxiciy of 1,2 dichlorobenzene to Daphnia magna over 21 days, which is recommended by the OECD guideline, the reported NOEC was higher than the EC16 reported by Calamari et al, 1983. Therefore, as a worst case the EC16 of 0.37 mg/L, reported by Calamari et al (1983) has been selected to represent the long term toxicity of 1,2 dichlorobenzene to aquatic invertebrates.