2-Pyridinesulfonamide, N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]-3-(2,2,2-trifluoroethoxy)-, sodium salt (1:1)

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

4.99 ng/L

Assessment factor:

10

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.499 ng/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

4.99 ng/L

Assessment factor:

10

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

100 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

18.2 ng/kg soil dw

Assessment factor:

50

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Selection of endpoints for the PNECaquatic

There are four toxicity studies conducted with Lemna gibba. The species was found to be the most sensitive amongst all aquatic species tested, including all microalgal species and one more macrophyte species. Only two out of the four available studies are considered appropriate for the calculation of PNECs and are therefore used for deriving a geometric mean which is consecutively used for the derivation of the PNEC.

Studies excluded:

The first study that was excluded from PNEC derivation (Kranzfelder, 2000) presents results for the following concentrations: 0.2, 0.6, 1.7, 5.2, 18, 56 and 190 ng/L of the substance. The results show statistically significant reduction in growth compared to the solvent control for the concentrations 0.2 to 18 ng/L varying between 12 to 20%. For the same range of concentrations very good recovery was observed within a week after the exposure was terminated. For the two highest concentrations (56 and 190 ng/L) the reduction observed was of 97% and 99%, respectively and no recovery was achieved after the end of the exposure period for the plants that were exposed to these two treatments levels. According to the results, the NOEC based on growth reduction (frond number) was <0.2 ng/L. The major reason for the exclusion of this study is that the authors mentioned that only the normal frond numbers were counted. This may have lead to an over-conservative estimation of the effects. Dead fronds may be identified by a total discoloration (yellow, white, black or clear) of the entire frond and it seems that the authors may have not counted the smaller fronds or the partially deformed ones (implied by the presentation of the results) and in that case they may have overestimated the effects. In addition, in a preliminary test discussed within the same study, at the concentration of 0.2 ng/L an increase in frond number compared to controls of 6% was observed, which was not observed in the definitive test. Due to the above, the NOEC presented in this study is not considered for the derivation of the aquatic PNEC.

The second study that is excluded from PNEC derivation (Sunderland et al., 2001) which concluded the highest NOEC (100 ng/L) value amongst the four studies on Lemna. This study is the only one that was conducted with no renewals of the test solutions for the entire exposure period of 14 days and with only one analytical measurement of the test solution, with samples taken at day 0 of the experiment. The NOEC value was derived on the basis of nominal concentrations. Using the nominal value in this case is not a valid assumption, particularly when in the first study was shown that the substance degraded by >50% within 3 days in the test medium. However, it is noted that these two studies used different test mediums.

The third study that was not included in PNEC derivation (Knauer, 2002) was performed on Glyceria maxima variegate (sweet reed grass), which was found to be less sensitive than Lemna gibba (duckweed) under similar test conditions. Although the study demonstrated that sweet reed grass was less sensitive than duckweed to the effects of the test material, it nevertheless demonstrated that the test substance had significant toxic effects on sweet reed grass. Although not included for the calculation of PNECs, the study was provided as supporting information.

Conclusion on classification

In accordance with criteria for classification as defined in Annex I Point 4 Regulation 1272/2008, the test material requires classification for acute and chronic aquatic toxicity, meeting the criteria for acute category 1 and chronic category 1. A chronic M factor of 1000 has been assigned based on the most sensitive species, Lemna gibba. An acute M factor of 100 has been assigned on the basis of the most sensitive species in the acute toxicity studies, algae.

In accordance with criteria for classification as defined by Directive 2001/59/EC, Annex VI, Point 5.2.1, the test material requires classification for acute and chronic aquatic toxicity, meeting the criteria for R50-53, very toxicity to aquatic organisms and may cause long-term adverse effects in the aquatic environment.