Registration Dossier

Administrative data

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:
PNEC aqua (freshwater)
PNEC value:
0.008 mg/L
Assessment factor:
1 000
Extrapolation method:
assessment factor

Marine water

Hazard assessment conclusion:
PNEC aqua (marine water)
PNEC value:
0.001 mg/L
Assessment factor:
10 000
Extrapolation method:
assessment factor

STP

Hazard assessment conclusion:
PNEC STP
PNEC value:
10 mg/L
Assessment factor:
10
Extrapolation method:
assessment factor

Sediment (freshwater)

Hazard assessment conclusion:
PNEC sediment (freshwater)
PNEC value:
0.055 mg/kg sediment dw
Extrapolation method:
equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:
PNEC sediment (marine water)
PNEC value:
0.006 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:
0.006 mg/kg soil dw
Extrapolation method:
equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:
no potential for bioaccumulation

Additional information

Acute data is available for freshwater fish, Daphnia magna and algae. An activated sludge respiration inhibition test is also available. Aquatic PNECs were derived from the lowest freshwater L(E)C50, the ErC50 of 7.8 mg/L for the freshwater algae Selenestrum capricornutum.

PNECfreshwater = 0.0078 mg/L

PNECmarine = 0.00078 mg/L

PNECs for freshwater and marine sediment were calculated from the PNECfreshwater using the equilibrium partitioning method (EPM). Calculations were made based on a molecular weight of 222 g/mol, a vapour pressure of 0.0001079 Pa, a water solubility of 822 mg/L at 25oC, and a Koc of 34 (calculated from a log Kow of 1). EPM PNECs are considered to be conservative and worst-case for the risk assessment.

PNECfreshwater sediment = 0.0551 mg/kg dw

PNECmarine sediment = 0.00551 mg/kg dw

The PNEC for soil was also calculated by equilibrium partitioning from the values outlined above.

PNECsoil = 0.00645 mg/kg dw

The PNECstp was calculated using the NOEC from the activated sludge respiration inhibition test and an assessment factor of 10.

PNECstp = 10 mg/L

It was not considered necessary to derive PNECs for air or secondary poisoning as there is no hazard for these compartments.

Conclusion on classification

As the lowest acute L(E)C50 is 7.8 mg/L, the substance does not meet the requirements for classification as acutely toxic to the aquatic environment.

No chronic data is available. As an inorganic metal the substance cannot be considered to be rapidly biodegradable as biodegradability is not relevant in this case. For a standard organic chemical this might lead to a classification as toxic to the aquatic environment, chronic category 2. However in this case further consideration should be given.

The toxicity of the test substance in acute studies is likely to be driven by the availability of dissociated barium ions which react with biological systems to manifest effects. Dissociated barium is known to be highly reactive in the environment.

However once emitted to the environment barium ions will not exist in their ionic state due to their high level of reactivity. Thus upon contact with organic fractions such as humic acid the barium ions will react to form barium metallic complexes which are common in the environment, are generally non-toxic and are essentially inert.

As such the test substances itself and its dissociation products (notably barium ions) will not exist beyond the short term in the environment and will rapidly react with organic molecules to form unreactive barium complexes. Given this, though the barium ions may cause toxic effects in the short term, long terms effects are not expected as bioavailability of the emitted barium will be limited once it reacts in the environment.

As such long term exposure or persistence are not foreseen and thus a chronic classification is not proposed.