2-Pyridinecarboxamide, 4-[4-[[[[4-chloro-3-(trifluoromethyl)phenyl]amino]carbonyl]amino]phenoxy]-N-methyl-

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Aug - Dec 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)

Deviations:

no

Principles of method if other than guideline:

Not relevant

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

Chironomus riparius

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

artificial sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

2.85 mg/kg sediment dw

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

emergence rate

Emergence ratio showed a clear dose-response relationship compared to the solvent control after a 28 d exposure period. Development rate was not inhibited at 10 mg/kg dry sediment. Measured initial concentrations were within ± 20% of the nominal concentrations (mean recovery: 87.2% of nominally applied test item). Therefore, the biological effect concentrations were expressed based on the nominal concentrations. After 28 days, mean recovery of applied test item was 89.3%.

Validity criteria fulfilled:

yes

Conclusions:

The EC50 for emergence ratio was found to be 2.85 mg/kg sediment after 28 d.

Executive summary:

The aim of this study was to determine the lethal and sublethal effects of the test item on the larvae of Chironomus riparius. To achieve this aim, first-instar larvae were exposed in a sediment-water system to a series of test item concentrations applied to the sediment phase of a sediment-water system. Test vessels without the addition of the test item served as controls. The test item was spiked into the formulated sediment, and the test organisms were subsequently introduced into the test vessels in which the sediment and water concentrations had been equilibrated for 2 days. The test animals were exposed to the systems for a period of 28 days which is considered to be sufficient to assess the impact of the test item on full maturation of the larvae to adult midges. The larvae were fed during the exposure period to ensure that the animals grew and emerged under control conditions. Endpoints based on emergence ratio (number of emerged adults compared with number of larvae introduced per vessel) and development rate (time elapsed between introduction of larvae to treated vessels and emergence of adults) were assessed in comparison to a control. Parameters were the total number of emerged adults and the development rate. In addition, different sensitivities of sexes were assessed. Since there were no indications of significantly different sensitivities of sexes, male and female results were pooled for statistical analysis. The data obtained concerning the toxicological effects of the test item on the test organisms were used to determine an ECx (e.g. EC50, EC20, EC15). In addition, the lowest observed effect concentration (LOEC) and hence the no observed effect concentration (NOEC) were determined. To verify the nominally applied concentrations, samples were taken from overlying water, pore water and sediment and analytically measured. The samples designated for chemical analysis were shipped to the analytical Test Site and analysed under the responsibility of the Principal Investigator for Analysis.

Emergence ratio showed a clear dose-response relationship compared to the solvent control after a 28 d exposure period. Development rate was not inhibited at 10 mg/kg dry sediment. Measured initial concentrations were within ± 20% of the nominal concentrations (mean recovery: 87.2% of nominally applied test item). Therefore, the biological effect concentrations were expressed based on the nominal concentrations. After 28 days, mean recovery of applied test item was 89.3%.

Description of key information

A guideline study according to OECD Guideline 218 (Sediment-water Chironomid Toxicity Test Using Spiked Sediment) was performed under GLP to assess the acute sediment toxicity of BAY 43-9006 to Chironomus riparius. Larvae of Chironomus riparius were exposed to the test substance at 5 concentrations: 10, 5.0, 2.5, 1.25, and 0.625 mg test item/kg dry sediment over a period of 28 days. Additionally a solvent control and a control treatment were prepared. To verify the nominally applied concentrations, samples were taken from overlying water, pore water and sediment and analytically measured. Endpoints based on emergence ratio (number of emerged adults compared with number of larvae introduced per vessel) and development rate (time elapsed between introduction of larvae to treated vessels and emergence of adults) and were assessed in comparison to a control. In addition, different sensitivities of sexes were assessed. Since there were no indications of significantly different sensitivities of sexes, male and female results were pooled for statistical analysis. Emergence ratio showed a clear dose-response relationship compared to the solvent control after a 28 d exposure period. Development rate was not inhibited at 10 mg/kg dry sediment. The EC50 for emergence ratio was found to be 2.85 mg/kg sediment after 28 d.

Key value for chemical safety assessment

EC50 or LC50 for freshwater sediment:

2.85 mg/kg sediment dw