Barium 4-dodecylphenolate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.7 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.07 µg/L

Assessment factor:

100

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

no hazard identified

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

3.49 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.35 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:

697.32 µg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

1.37 mg/kg food

Assessment factor:

90

Additional information

The fate and toxicity of barium 4-dodecylphenolate in the environment is most accurately evaluated by separately assessing the fate of its moieties barium and 4-dodecylphenolate.

Barium 4-dodecylphenolate consists of a metal cation and a phenolate anion. Based on the solubility of barium 4-dodecylphenolate in water, dissociation of barium4-dodecylphenolate resulting in barium cations and 4-dodecylphenolate anions may be assumed under environmental conditions.he respective dissociation is reversible, and the ratio of the salt /dissociated ions is dependent on the metal-ligand dissociation constant of the salt, the composition of the solution and its pH.

A metal-ligand complexation constant of barium 4-dodecylphenolate could not be identified. Data for barium appear to be generally limited. However, barium ions tend to form complexes with ionic character as a result of their low electronegativity. Further, the ionic bonding of barium is typically described as resulting from electrostatic attractive forces between opposite charges, which increase with decreasing separation distance between ions.

 

Based on an analysis by Carbonaro et al. (2011) of monodentate binding of barium to negatively-charged oxygen donor atoms, monodentate ligands such as 4-dodecylphenolate anions are not expected to bind strongly with barium.The analysis by Carbonaro & Di Toro (2007) suggests that the following equation models monodentate binding to negatively-charged oxygen donor atoms of functional groups:

log KML= αO* log KHL+ βO; where

KML is the metal-ligand formation constant, KHL is the corresponding proton–ligand formation constant, and αO and βO are termed the Irving–Rossotti slope and intercept, respectively. Applying the equation and parameters derived by Carbonaro & Di Toro (2007) and the pKa of dodecylphenol of 10.31 results in:

log KML= 0.186 * 10.31 – 0.171

log KML= 1.75 (estimated barium 4-dodecylphenolate formation constant).

Thus, it may reasonably be assumed that based on the estimated barium-dodecylphenolate formation constant, the respective behaviour of the dissociated barium cations and 4-dodecylphenolate anions in the environment determine the fate of barium 4-dodecylphenolate upon dissolution with regard to (bio)degradation, bioaccumulation, partitioning resulting in a different relative distribution in environmental compartments (water, air, sediment and soil) and subsequently its ecotoxicological potential.

In the assessment of environmental fate and toxicity of barium 4-dodecylphenolate, read-across to the assessment entities soluble barium substances and 4-dodecylphenolate is applied since the ions of barium 4-dodecylphenolate determine its environmental fate. Since barium cations and 4-dodecylphenolate anions behave differently in the environment, including processes such as stability, degradation, transport and distribution, a separate assessment of the environmental fate of each assessment entity is performed. Please refer to the data as submitted for each individual assessment entity. For a documentation and justification of that approach, please refer to the separate document attached to section 13, namely Read Across Assessment Report for barium 4-dodecylphenolate.

Conclusion on classification

For barium 4-dodecylphenolate, aquatic toxicity studies are not available. Read-across to the assessment entities soluble barium substances and dodecylphenolate is applied for the assessment of barium 4-dodecylphenolate since the ions of barium 4-dodecylphenolate determine its fate and toxicity in the environment. Reliable data available for soluble barium substances and dodecylphenolate indicate that the moiety of ecotoxicological concern are dodecylphenolate anions.

Acute (short-term) toxicity data: EC/LC50 values of 3 trophic levels (algae, invertebrates and fish) range for barium from > 1.15 mg Ba/L to 14.5 mg Ba/L. According to QSAR-based predictions, dodecylphenolate has a potential for acute toxicity to fish and aquatic invertebrates since EC/LC50 values available for 2 trophic levels range from 0.038 mg/L to 0.112 mg/L. The aquatic hazard assessment is based on the most toxic moiety, i.e. the dodecylphenolate anions, and the lowest effect concentrations (acute ecotoxicity reference value) is recalculated for barium 4-dodecylphenolate based on a maximum dodecylphenolate content of 81 %.

Barium 4-dodecylphenolate meets based on i) the lowest acute aquatic ecotoxicity value of 0.038 mg/L dodecylphenolate; ii) the maximum dodecylphenolate content of barium 4-dodecylphenolate of 81%, and iii) the resulting acute ecotoxicity reference value of 0.047 mg/L barium 4-dodecylphenolate, classification criteria of acute (short-term) aquatic hazard Category 1 of Regulation (EC) No 1272/2008 with an acute M-Factor of 10.

 

Long-term (chronic) toxicity: NOEC/EC10 values of 3 trophic levels (algae, invertebrates and fish) range from ≥ 1.15 mg Ba/L to 2.9 mg Ba/L. According to QSAR-based predictions, dodecylphenolate has a potential for chronic toxicity to fish, aquatic invertebrates and algae since the chronic ChV values range from 0.0057 mg/L to 0.026 mg/L. The aquatic hazard assessment is based on the most toxic moiety, i.e. the dodecylphenolate anions, and the lowest effect concentrations (chronic ecotoxicity reference value) is recalculated for barium 4-dodecylphenolate based on a maximum 4-dodecylphenolate content of 81 %.

Barium 4-dodecylphenolate meets based on i) the lowest chronic aquatic ecotoxicity value of 0.0057 mg/L dodecylphenolate; ii) the maximum dodecylphenolate content of barium 4-dodecylphenolate of 81%, and iii) the resulting chronic ecotoxicity reference value of 0.007 mg/L barium 4-dodecylphenolate, classification criteria of long-term (chronic) aquatic hazard Category 1 of Regulation (EC) No 1272/2008 with a chronic M-Factor of 10.