Zinc bis(benzenesulphinate)

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

5.9 µg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

59 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.59 µg/L

Assessment factor:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

0.25 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

25 µg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

2.5 µg/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:

1.56 µg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

No long-term studies were available. Available short term studies showed LC50 (96h) on fish > 100 mg/l, EC50 (48h) on daphnia = 5.9 mg/l and EC50 (72h) on algae > 100 mg/l. The lowest value, i.e. EC50 = 5.9 mg/l, was used in the calculation of PNEC_water .

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, i.e. 5.9 mg/l.

The value of PNEC_stpwas derived using the concentration at which no toxicity to inoculum was seen in a ready biodegradability assay. Such concentration can be considered as a NOEC for the toxicity to STP microorganisms. Therefore, a concetration of 2.5 mg/l was used and an assessment factor of 10 was applied.

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. The suspended matter-water partition coefficient was computed and resulted as 1.06 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_waterfor aquatic organisms and soil-water partition coefficient were used as inputs. Bulk density of wet soil is 1700 kg/m³. Soil-water partition coefficient was computed and resulted as 0.397 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 -0.39, 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.

Test substance was found to be soluble and stable in test medium under test conditions. In a ready biodegradability assay, the substance resulted as ready biodegradable.

In short term studies on fish, daphnia and algae, daphnia resulted to be the most sensitive species, with an EC50 value of 5.9 mg/l after a 48 h exposure. Based on these results, no classification for acute toxicity is applied.

No chronic toxicity data was available from long-term studies.

In case of lack of chronic data, a decision on classification is based on acute toxicity data, potential of degradability and potential of bioaccumulation.

In particular, substances for which adequate chronic toxicity data are not available, are classified in:

- category chronic 1, when E(L)C50 < 1 mg/l

- category chronic 2, when E(L)C50 between 1 and 10 mg/l

- category chronic 3, when E(L)C50 between 10 and 100 mg/l

and the substance is not rapidly degradable and/or the experimentally determined BCF ≥ 500 (or, if absent, the log Pow ≥ 4).

As the lowest EC50 value of test substance is between 1 and 10 mg/l, but the substance is ready biodegradable and has a logPow < 4, no classification for chronic aquatic toxicity is applied according to the CLP Regulation (EC 1272/2008).