Diboron trioxide

Toxicity to terrestrial arthropods

Administrative data

Endpoint:

toxicity to terrestrial arthropods: long-term

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: no accepted standard guideline followed, well performed study, raw data not available

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Materials and methods

Test guideline

Qualifier:

no guideline followed

Deviations:

not applicable

Principles of method if other than guideline:

test protocol "environment canada (2000)" was followed

GLP compliance:

not specified

Application method:

soil

Test material

Test material information

Constituent 1

Reference substance name:

Boric acid

EC Number:

233-139-2

EC Name:

Boric acid

Cas Number:

10043-35-3

Molecular formula:

H3BO3

IUPAC Name:

Boric acid

Details on test material:

- Name of test material (as cited in study report): boric acid
- Physical state: 98.29% pure powder
- origin: Fisher Scientific (catalog no A74-500, Fair Lawn, NJ, USA)

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
nr

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

nr

Test substrate

Vehicle:

not specified

Details on preparation and application of test substrate:

Test compound (H3BO3) added in solution to soil and the soil/water mixture was mixed for about three minutes. Soil moisture was 35% (based on wet weight). Equilibration period before start of test: 1 day.

Test organisms

Test organisms (species):

Onychiurus sp.

Animal group:

Collembola (soil-dwelling springtail)

Details on test organisms:

TEST ORGANISM
- Common name: springtail (Onychiurus folsomi)
- Source: synchronous and asynchronous cultures in artificial soil
- Age at test initiation (mean and range, SD): medium and large (>= 2mm) adults

Study design

Study type:

laboratory study

Limit test:

no

Total exposure duration:

35 d

Remarks:

static

Test conditions

Test temperature:

20 +/- 2°C

pH (if soil or dung study):

- artificial soil: 6.09 (the pH of treated soil varies from 7.41 to 7.66 and from 6.77 to 7.36 at start and end of test, respectively)
- clay loam reference soil: 6.05 (the pH of treated soil varies from 5.60 to 5.73 and from 5.57 to 5.69 at start and end of test, respectively)

Photoperiod and lighting:

- Photoperiod: 16h light, 6h dark
- Fluorescent illumination

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 125 ml glass, wide-mouth, mason jar. cover: metal lid with rubber seal and screw ring.
- Amount of soil or substrate: 30g
- No. of treatments: 10
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 10 (4 for acute tests)



SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: clay loam reference soil: field collected soil from Alberta (Canada) and classified as a Delacour Orthic Black Chernozem.
- pH water (1:2) 6.05
- eCEC 34.5 cmol c/kg
- Soil texture (if natural soil)
- % sand: 26.6
- % silt:43.3
- % clay: 30.1
- % organic matter: 12.8
- % total carbon: 6.83
- OM: 12.8%
- Cb: 1.0 mg B/kg dw


ARTIFICIAL SOIL
- Ingrediënts: 70% silica sand, 20% kaolinite clay, 10% sphangum peat and 0.25% calcium carbonate.
- pH water (1:2) 6.09
- eCEC 18.5 cmol c/kg
- Soil texture
- % sand: 77.3
- % silt: 7.8
- % clay: 14.9
- % organic matter: 9
- % total carbon: 4.46
- OM: 9%
- Cb: 3.5 mg B/kg dw


SOIL PREPARATION
- Test compound H3BO3 added in solution to soil and the soil/water mixture was mixed for about 3 minutes. Soil moisture was 35% based on wet weight.

Endpoints: mortality and juvenile production (mean number of juveniles produced) and reproduction (adult fecundity, i.e. mean number of juveniles produced per adult).

Nominal and measured concentrations:

nominal:
chronic tests: 0-50-75-125-250-500-650-850-1000-1500 mg boric acid/kg dw
acute tests: 0-2000-4000-5000-6000-8000-10000 mg boric acid/kg dw and 0-125-250-500-1000-1500-2000 mg boric acid/kg dw in the artificial and clay loam reference soil respectively

Reference substance (positive control):

not specified

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

35 d

Dose descriptor:

NOEC

Effect conc.:

43.75 mg/kg bw

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

B

Basis for effect:

reproduction

Remarks:

(juvenile production)

Remarks on result:

other: artificial soil

Effect concentrations 2

Duration:

35 d

Dose descriptor:

NOEC

Effect conc.:

175 mg/kg bw

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

B

Basis for effect:

mortality

Remarks on result:

other: artificial soil

Effect concentrations 3

Duration:

35 d

Dose descriptor:

NOEC

Effect conc.:

87.5 mg/kg bw

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

B

Basis for effect:

reproduction

Remarks:

(adult fecundity)

Remarks on result:

other: artificial soil

Effect concentrations 4

Duration:

35 d

Dose descriptor:

NOEC

Effect conc.:

21.9 mg/kg bw

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

B

Basis for effect:

reproduction

Remarks:

(juvenile production)

Remarks on result:

other: clay loam soil

Effect concentrations 5

Duration:

35 d

Dose descriptor:

NOEC

Effect conc.:

113.8 mg/kg bw

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

B

Basis for effect:

mortality

Remarks on result:

other: clay loam soil

Effect concentrations 6

Duration:

35 d

Dose descriptor:

NOEC

Effect conc.:

21.9 mg/kg bw

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

B

Basis for effect:

reproduction

Remarks:

(adult fecundity)

Remarks on result:

other: clay loam soil

Details on results:

- Ratio of culture units that produced viable eggs relative to the total number of culture units was about 30%.
- Adult survivorship was greater than 94%.

Reported statistics and error estimates:

7- and 14-day LCx values were generated using the Probit, Moving Average and the Trimmed Spearman-Karber methds. ECx values and their associated 95% confidence limits for the chronic tests were analysed by using either a linear or four nonlinear regression models (i.e., logistic, Gompertz, exponential and logistic with hormoesis). If data showed heteroscedasticity among treatments, data were weighed with the inverse of the variance of each treatment. NOEC values were estimated using ANOVA, Dunnett’s and Fischer’s protected LSD (Least Significant Difference) pairwise comparison tests.

Any other information on results incl. tables

Boric acid had an adverse effect upon survival of O. folsomi following 35d of exposure in spiked artificial and cly loam soil.

O. folsomi reproduction was more sensitive to boric acid than adult survival.

35d LC50:

- artificial soil: 88 (juvenile production), 258.3 (mortality), 94.8 (reproduction) mg B/kg

- caly loam soil: 19.7 (juvenile production), 174.6 (mortality), 32.4 (reproduction) mg B/kg

7d LC50: 652.6 (mortality, artificial soil); 316.2 (mortality, clay loam soil) mg B/kg

14d LC50: 248.48 (mortality, clay loam soil) mg B/kg

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

Study not according to an international guideline.
The study itself is well performed but raw data is not available. NOEC values are used for PNEC derivation.