Strontium hydroxide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

2.1 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

no data: aquatic toxicity unlikely

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

4.2 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

2 720 mg/kg sediment dw

Assessment factor:

1

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

no hazard identified

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

329 mg/kg soil dw

Assessment factor:

1

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

PNEC sediment:

The PNEC_sediment can be derived from the PNEC_aquatic using the equilibrium partitioning method (EPM).

A distribution/partition coefficient (K_D) between the water and sediment compartment for strontium has been determined. This resulted in a typical K_{D, susp-water} of 1,291.8 L/kg (logK_D: 3.11). In a first step the units have to be converted from L/kg to m³/m³ using the formula below.

K_{D, susp-water}(m³/m³) = 0.9 + [0.1 x (K_{D, susp-water}(L/kg) x 2,500) / 1,000]

This results in a K_{D, susp-matter} of 323.9 m³/m³. This value can be entered in the equation below to calculate the PNEC_sediment:

PNEC_sediment = (K_{D, susp-water}/ RHO_susp) x PNEC_aquatic x 1,000

with the PNEC_aquatic expressed as mg/L, RHO_susp representing the bulk density of wet suspended matter (freshly deposited sediment) (1,150 kg/m³), and a K_{D, susp-water} of 323.9 m³/m³, a PNEC_sediment that is expressed as mg/kg wet weight can be derived. This value can be converted to a dry weight-based PNEC, using a conversion factor of 4.6 (CONVsusp = RHOsusp/Fsolid-susp * RHOsolid) kg wet weight/ kg dry weight.

This results in a PNEC_sediment of 2,720 mg Sr/kg dry sediment

PNEC soil:

The PNEC_soil can be derived from the PNEC_aquatic using the equilibrium partitioning method (EPM).

A distribution/partition coefficient (KD) between the water and soil compartment was derived for strontium of 157.03 L/kg (Log KD: 2.2). In a first step the units have to be converted from L/kg to m³/m³ using the formula below.

KD,_soil (m³/m³) = 0.2 +[0.6 x (KD,_soil (L/kg) x 2,500) / 1,000]

This results in a KD,_soil of 235.75 m³/m³. This value can be entered in the equation below to calculate the PNEC_soil

PNEC_soil = (KD,_soil/ RHO_soil) x PNEC_aquatic x 1,000

With the PNEC_aquatic expressed as mg/L, RHO_soil representing the bulk density of wet soil (1,700 kg/m³) and KD,soil is 157.03 m³/m³, a PNEC_soil expressed as mg/kg wet weight is derived. This value can be converted to a dry weight-based PNEC, using a conversion factor of 1.13 kg wet weight/ kg dry weight.

 

This results in a PNEC_soilof 329 mg Sr/kg dry soil

Conclusion on classification

Short-term toxicity EC/LC50 values of Sr available for 3 trophic levels are situated between >40.3 mg Sr/L and >125 mg Sr/L, corresponding to > 55.9 mg/L and 173.6 mg/L strontium hydroxide based on an average Sr content of 72%. In accordance with Regulation (EC) No 1272/2008, Table 4.1.0 (a), classification for acute aquatic hazard is not required for strontium hydroxide as all EC50/LC50 values are above the classification criteria of 1 mg/L.

Long-term toxicity data are available for three trophic levels and range from 21 mg Sr/L to ≥ 43.3 mg Sr/L, corresponding to 29.2 mg/L and 60.1 mg/L strontium hydroxide based on an average Sr content of 72%. In accordance with Regulation (EC) No 1272/2008, Table 4.1.0 (b) (i), classification for chronic aquatic hazard is not required for strontium hydroxide as all chronic EC10/NOEC values are above the classification criteria of 1 mg/L.