Trisodium 1-(1-naphthylazo)-2-hydroxynaphthalene-4',6,8-trisulphonate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.1 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

1 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.01 mg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

10 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.392 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.039 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:

0.02 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Calculation of PNEC_waterwas based on results obtained in short-term studies on fish, daphnia and lemna, namely L(E)C50 > 100 mg/l. These results indicate the lack of acute toxicity for the three trophic levels at least up to concentration of 100 mg/l. Assessment factors of 1000 and 10000 were used for fresh water and marine water, respectively.

The derivation of PNEC_{water, intermittent}was done by applying an assessment factor of 100 to the lowest value obtained in at least three short-term aquatic toxicity studies from three trophic levels. Accordingly, a concentration of 100 mg/l was used.

The value of PNEC_stpwas derived from the result of the activated sludge respiration inhibition test EC50 > 1000 mg/l by using an assessment factor of 100.

Due to the lack of ecotoxicological data, PNEC_sedimentfor fresh water and marine water were calculated using equilibrium partitioning method. This method uses PNEC_waterfor aquatic organisms and suspended matter/water partition coefficients as inputs. Bulk density of wet suspended matter is 1150 kg/m³. Note that this approach is used only as a rough screening since it may result in both an overestimation or underestimation of toxicity. A predicted value for partition coefficient organic carbon-water was available, namely K_oc = 3.16 l/kg at 20 °C. Based on this data, the suspended matter-water partition coefficient was computed and resulted as 0.979 m³/m³. A correction factor of 4.6 from wet weight to dry weigth was applied to obtain the final PNEC_sediment.

The amount of test substance in the air compartment was expected to be very low, since the substance is a solid with a negligible vapour pressure. Therefore, no hazard was identified.

The calculation of PNEC_soilwas done using the equilibrium partitioning method, based on the assumption that soil toxicity, expressed in terms of freely-dissolved substance concentration in the pore water, is the same as aquatic toxicity. The pore water concentration is correlated with the bioavailable fraction. Note that this approach was originally developed for sediments but it may be applied to soil. In the calculation of PNEC_soil, PNEC_water for aquatic organisms and soil/water partition coefficient are used as inputs. Bulk density of wet soil is 1700 kg/m³. Based on a K_oc of 3.16, the soil-water partition coefficient was computed and resulted as 0.295 m³/m³. A correction factor of 1.13 from wet weight to dry weight was applied to obtain the final PNEC_soil.

Secondary poisoning concerns toxic effects in the higher members of the food chain which results from ingestion of organisms from lower trophic levels that contain accumulated substances. It is relevant for highly lipophilic organic chemicals, with a log P_ow above the cutoff value of 4 reported in the CLP Regulation (EC 1272/2008). Due to the absence of potential for bioaccumulation indicated by a log P_ow of -2.2671, test substance was considered as not hazardous with respect to secondary poisoning.

Conclusion on classification

According to the CLP Regulation (EC 1272/2008), the threshold of classification of a substance for acute aquatic toxicity is 1 mg/l. This limit is compared with LC50 (96h) for fish, EC50 (48 h) for daphnia and EC50 (72 - 96 h) for algae or aquatic plants.

Test substance has high water solubility, i.e. above 300 g/l at 20 °C. The substance was soluble at concentrations reported in available tests and no signs of precipitation were reported in tested media. Moreover, test consentrations were found to be stable for tests duration.

 

In the available 96-hour test on fish, no mortality was recorded up to the highest tested dose of 1000 mg/l.

Toxicity on daphnia was assessed in a 48 -hour study, where no acute immobilisation was seen in daphnids exposed up to a concentration of 100 mg/l.

Toxicity on aquatic plants was assessed in a 7 -day test on lemna. No effects were reported at 100 mg/l concentration of a.i..

In all studies, no acute toxicity was recorded up to the highest tested doses, thus no 50 % effect levels could be established.

No chronic toxicity data was available from long-term studies. In case of lack of chronic data, the potential for chronic toxicity is identified by appropriate combinations of acute toxicity data and lack of biodegradability. The threshold of classification is 100 mg/l.

Overall, based on the lack of acute toxicity by test substance at the threshold level of 100 mg/l, no classification for both acute and chronic aquatic toxicity was applied according to the CLP Regulation (EC 1272/2008).