Barium titanium trioxide

Toxicity to soil macroorganisms except arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to soil macroorganisms except arthropods: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Guideline test, but conducted in a natural soil that promotes bioavailability of metal cations (e.g., Ba): relatively low pH , low organic matter, low cation exchange capacity, and high sand content

Qualifier:

according to guideline

Guideline:

ISO 11268-2 (Effects of Pollutants on Earthworms. 2. Determination of Effects on Reproduction)

Deviations:

yes

Remarks:

21d-earthworm reproduction test, measuring adult survival and juvenile production. Method was modified for use with natural soil having a physical and chemical characteristics that support a relatively high level of metal bioavailability. Modifications in

GLP compliance:

not specified

Remarks:

There is no reference to GLP in the publication

Specific details on test material used for the study:

purity 99%
source: Fisher Scientific, Pittsburgh, PA, USA

Analytical monitoring:

yes

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Details on test organisms:

no details provided

Study type:

laboratory study

Substrate type:

natural soil

Limit test:

no

Total exposure duration:

21 d

pH:

control soil pH: 5.29
pH decreased with increasing substance-levels , but the decrease was less than 1 pH-unit

Moisture:

according to guideline specification (95% of the water holding capacity)

Details on test conditions:

Soil type: Sassafras sandy loam SSL (fine-loamy, siliceous, mesic Typic Hapludult), collected from open grassland field; 71% sand, 18% silt, 11% caly, 1.2% organic matter, 4.3 cmol/kg CEC, pH 5.29, - Ba background 34 mg/kg dw
- 7-9 test concentrations (not specified)
- 4 replicates/concentration
- soils were aged and weathered for 3 weeks to simulate, at least in part, weathering & aging of barium in soil and to approximate more closely the exposure effects on soil biota in the field, incl. exposing amended soils, initially hydrated to 60% of the WHC, in open plastic bags in the greenhouse to alternating wetting and air-drying cycles for three weeks before definitive testing. Soil treatments were monitored & adjusted to initial weights twice each week and brought to 95 % of the WHC for the test.

Nominal and measured concentrations:

7-9 concentrations; exact nominal/measured levels not specified
measured range: 34 (control) -3700 mg/kg
Mean analytical recovery: 109% (survival test), 112% (cocoon test).

Reference substance (positive control):

yes

Remarks:

4-nitrophenol

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1 348 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Basis for effect:

mortality

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

1 585 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Basis for effect:

mortality

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

258 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

433 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

other: EC20

Effect conc.:

370 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Basis for effect:

reproduction

Remarks on result:

other: 230-510

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

664 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Basis for effect:

reproduction

Remarks on result:

other: 558-770

Details on results:

Good overal agreement among nominal and measured concentrations was noted.
Ba-background is SSL soil was 34 mg/kg
Barium concentrations (in excess of background) in the experimental treatments ranged from 88 to 139%, and averaged 111% of nominal.

Reported statistics and error estimates:

Toxicity data were analyzed using non-linear regression models. Variances of the residuals were examined to decide wether to weight the data and to select potential models. The logistic (Gompertz) model was used.
Analysis of variance was used to determine the bounded NOEC and LOEC for adult survival or reproduction data. Mean separations were determined using Fisher's least-significant-difference pairwise comparison tests.

Validity criteria fulfilled:

not specified

Conclusions:

A guideline study with the earthworm Eisenia fetida, using a natural soil, has been conducted with barium nitrate. NOEC, LOEC, EC20 and EC50 values - based on measured levels - are reported for survival and/or reproduction. Data can be used for the effects assessment of barium in the terrestrial compartment.

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for soil macroorganisms:

391 mg/kg soil dw

Additional information

Kuperman et al (2006) reported reliable NOEC-values for barium (added as barium nitrate) for two different soil macro-organisms (E. fetida, E. crypticus). The derived effect values were based on ecological relevant endpoints (mortality and reproduction). Reproduction was the most sensitive endpoint, and NOEC-values were 258 and 433 mg barium/kg soil dw for E. fetida and E. crypticus, respectively.