Barium chloride

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Data available on BaCO3 has been used as a basis for BaCl2. In the assessment of the environmental fate and behaviour of barium substances, a read-across approach is applied based on all information available for inorganic barium compounds. This is based on the common assumption that after emission of metal compounds into the environment, the moiety of toxicological concern is the potentially bioavailable metal ion (i.e., Ba2+). The dissolution of barium substances in the environment and corresponding dissolved Ba levels are controlled by the solubility of barite (BaSO4) and witherite (BaCO3), two naturally occurring barium minerals (Ball and Nordstrom 1991; Menzie et al, 2008), and the concentration of dissolved Ba cations in freshwater is rather low. However, in the dissolved state, the divalent barium cation, is the predominant form in soil, sediments and water. The solubility of barium compounds increases as solution pH decreases (US EPA, 1985a). Nevertheless, the speciation of barium in the environment is considered to be rather simple (USEPA 2005):
- Barium cations are not readily oxidized or reduced
- Barium cations do not bind strongly to most inorganic ligands or organic matter

In sum, transport, fate, and toxicity of barium in the environment are largely controlled by the solubility of barium minerals. The barium cation is the moiety of toxicological concern, and thus the hazard assessment is based on Ba2+. Since the dissolved concentration of Ba2+ was determined in the current study, a full read-across is considered justified.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: EPA-821-R-02-014 Short-Term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to Freshwater Organisms. US Environmental Protection Agency, Cincinatti, Ohio, 350 pp.

Key result

Duration:

7 d

Dose descriptor:

EC10

Remarks:

EC10 estimated by non-linear regression of reproduction data from digitised figure as 60.79 µM Ba2+

Effect conc.:

12.66 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Remarks:

BaCl2 (conversion from µM Ba2+ to mg/L BaCl2 via molecular weight)

Basis for effect:

reproduction

Key result

Duration:

7 d

Dose descriptor:

EC10

Remarks:

EC10 estimated by non-linear regression of reproduction data from digitised figure as 60.79 µM Ba2+

Effect conc.:

8.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Remarks:

Ba2+

Basis for effect:

reproduction

Duration:

7 d

Dose descriptor:

other: EC25

Effect conc.:

15.2 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Remarks:

BaCl2 (conversion from µM Ba2+ to mg/L BaCl2 via molecular weight)

Basis for effect:

reproduction

Duration:

7 d

Dose descriptor:

other: EC25

Effect conc.:

10.02 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Remarks:

Ba2+

Basis for effect:

reproduction

Duration:

7 d

Dose descriptor:

EC50

Remarks:

geometric mean of the highest concentration with 100% survival and lowest concentration with 0% survival

Effect conc.:

30.19 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Remarks:

BaCl2 (conversion from µM Ba2+ to mg/L BaCl2 via molecular weight)

Basis for effect:

mortality

Duration:

7 d

Dose descriptor:

EC50

Remarks:

geometric mean of the highest concentration with 100% survival and lowest concentration with 0% survival

Effect conc.:

19.91 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Remarks:

Ba2+

Basis for effect:

mortality

Validity criteria fulfilled:

yes

Conclusions:

In a 7d toxicity assessment following effect concentrations were observed: EC10 for reproduction = 60.79 µM Ba2+ = 12.66 mg/L BaCl2 and EC50 for survival = 145 µM Ba2+ = 30.19 mg/L BaCl2

Executive summary:

The chronic toxicity of Ba2+ to Ceriodaphnia dubia has been assessed according to US EPA-821-R-02-014. The C. dubia are exposed to a range of Ba2+ concentrations in the form of BaCO3 for 7d and mortality and reproduction are recorded. Nominal test concentrations of 50, 100, 250, 500 and 1000 µM Ba2+ were used. All test concentrations were analytically verified by ion chromatography. 

In the publication an IC25 for reproduction has been calculated: 73 µM Ba2+ which corresponds to 15.20 mg/L BaCl2. For a figure in the publication additional effect levels could be derived: EC10 for reproduction of 60.79 µM, which corresponds to 12.66 mg/L BaCl2 and EC50 for survival of 145 µM Ba2+ which corresponds to 30.19 mg/L BaCl2. 

Description of key information

One reliable study has been identified, i.e. Brix et al. (2010). The long-term toxicity of BaCO3 to C.dubia was assessed in a 7-d study according to EPA-821-R-02-014. The reported, measured EC10 value is 8.3 mg/L Ba.

Two other supporting chronic toxicity studies were identified. the first study by Biesinger and Christensen reported a 21d-EC16 of 5.8 mg Ba/L (nominal values). The second data point was generated for the marine invertebrate Cancer anthonyi (Macdpnald et al, 1988). Here, a nominal, 7d-NOEC of 10 mg Ba/L was reported, and thids for the endpoint embryonal hatching.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC10

Effect concentration:

8.3 mg/L

Marine water invertebrates

Marine water invertebrates

Dose descriptor:

NOEC

Effect concentration:

10 mg/L

Additional information

The chronic toxicity of Ba2+ to Ceriodaphnia dubia has been assessed according to US EPA-821-R-02-014 by Brix et al. (2010). The C. dubia were exposed to a range of Ba2+ concentrations in the form of BaCO3 for 7d and mortality and reproduction are recorded. Nominal test concentrations of 50, 100, 250, 500 and 1000 µM Ba2+ were used. All test concentrations were analytically verified by ion chromatography. 

In the publication an IC25 for reproduction has been calculated: 73 µM Ba2+ (10.02 mg/L Ba2+) which corresponds to 15.20 mg/L BaCl2. For a figure in the publication additional effect levels could be derived: EC10 for reproduction of 60.79 µM Ba2+ (8.3 mg/L Ba2+), which corresponds to 12.66 mg/L BaCl2 and EC50 for survival of 145 µM Ba2+ (19.91 mg/L Ba2+) which corresponds to 30.19 mg/L BaCl2.