Diboron calcium tetraoxide

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

other: ASTM E729-95 Standard Guide for Conducting Acute Toxicity Tests on Test Materials with Fishes, Macroinvertebrates, and Amphibians

Qualifier:

equivalent or similar to guideline

Guideline:

EPA OPPTS 850.1075 (Freshwater and Saltwater Fish Acute Toxicity Test)

GLP compliance:

no

Remarks:

study is not in compliance with GLP

Analytical monitoring:

yes

Details on sampling:

each treatment at beginning and end of test

Vehicle:

no

Test organisms (species):

Pimephales promelas

Details on test organisms:

TEST ORGANISM
- Common name: Fathead minnow
- Source: Aquatic Biosystems, Fort Collins Colorado
- Age at study initiation (mean and range, SD): less than 7 d
- Feeding during test
- Food type:

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Hardness:

91

Test temperature:

24.7

pH:

8.0

Dissolved oxygen:

>6.0 mg/L

Nominal and measured concentrations:

Nominal: Control, 15.6, 31.3, 62.5, 125, 250 mg B/L
Measured: <0.022, 15, 32, 64, 125, 255

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 ml beakers
- Type : open
- Material, size, headspace, fill volume: glass, 200 ml
- Aeration: none
- Renewal rate of test solution: none

- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates):4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: MHRW (moderately hard reconstituted water) per US EPA 2002
- Total organic carbon: 0 nominal
- Particulate matter:
- Metals:
- Pesticides:
- Chlorine: 0 nominal
- Ca/mg ratio: 1.46
- Conductivity:
- Salinity:
- Culture medium different from test medium: Cultured at Aquatic Biosystems Lab water, hardness 114 mg/L, alkalinity 115 mg/L
- Intervals of water quality measurement: boron, pH, conductivity, alkalinity, hardness at beginning and end of test, temperature and D.O. daily

OTHER TEST CONDITIONS
- Adjustment of pH: none
- Photoperiod: 16 L: 8 D

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

79.7 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

element

Basis for effect:

mortality (fish)

Remarks on result:

other: (95% CI 72-88 mg B/L), control mortality 2.5%

Sublethal observations / clinical signs:

Data

Concentration (mg B/L)	Number dead (out of 40)	Percent Mortality
<0.022 (control)	1	2.5%
15	3 of 39	7.7%
32	0	0.0%
64	8	20.0%
125	38	95.0%
255	40	100.0%

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

The acute toxicity of boron has been studied with the dab (Limanda limanda) by subjecting them to a range of concentrations of the test material for 96 h in a continuous flow system. No standard guideline was identified, but methods were equivalent to standard fish toxicity testing methods.

GLP compliance:

yes

Remarks:

OECD, 1982

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

Limanda limanda

Details on test organisms:

TEST ORGANISM
- Common name: Dab
- Source: Uncontaminated south Devon environments
- Age at study initiation (mean and range, SD):
- Length at study initiation (length definition, mean, range and SD): mean length of 10.1 cm (range 7.0 - 13.2 cm)
- Weight at study initiation (mean and range, SD): mean weight of 16.9 g (range 5.6 - 30.8 g)
- Feeding during test: No feeding during test


ACCLIMATION
- Acclimation period: > 7 days in the laboratory, then acclimated to the test temperature of 12°C at a rate of 1-3 °C per day from their ambient temperature storage conditions. They were then maintained at the test temperature for a minimum of three days before being transferred to the test system where they were held for a minimum of 24 h under test conditions prior to the commencement of the exposure to the test substance.
- Feeding frequency: No feeding during acclimatisation

Test type:

flow-through

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

12 +-1 °C

pH:

7.7 +/- 0.8

Dissolved oxygen:

7.9 +/- 0.6 mg/L

Salinity:

34.6 +/- 0.2 ‰

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 30 L rectangular glass tanks
- Aeration: The test solutions were gently aerated with compressed air.
- Renewal rate of test solution (frequency/flow rate): 24h
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1


TEST MEDIUM / WATER PARAMETERS
- Intervals of water quality measurement: 24h

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

74 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Basis for effect:

mortality (fish)

Remarks on result:

other: 66.4-83.0 mg/L

Reported statistics and error estimates:

Probit analysis (Finney, 1971), of mortality observations every 24 h and measured test substance concentration gave the LC50 values for each substance.

Sublethal observations / clinical signs:

LC50 after 24h : 88.3 (80.3 - 97.3) mg/L

LC50 after 48h : 75.7 (68.0 - 85.0) mg/L

LC50 after 72h : 75.7 (68.0 - 85.0) mg/L

Conclusions:

The study was not conducted according to standard guidelines, but methods are equivalent to standard fish toxicity testing methods. Hence, the method is to be considered scientifically reasonable and the results can be considered as reliable to assess the toxicity towards fish. The test was conducted on the test material Disodium tetraborate.
The toxic effect towards fish was assessed on the saltwater species Dab (Limanda limanda) in a 96 h concentration-response test with flow-through conditions. The 96-hour LC50 was determined to be 74 mg/L based on the boron element. The exposure concentrations were verified by analytical measurements.

Executive summary:

The study was not conducted according to standard guidelines, but methods are equivalent to standard fish toxicity testing methods. The test was conducted on the test material Disodium tetraborate.

The purpose of this study was to determine the toxicity of the test item to fish. For this purpose, the saltwater species Dab (Limanda limanda) was exposed in a static test to various concentrations under defined conditions for 96 hours. The study encompassed 6 treatment groups (5 dose rates of the test item and a control) each containing 20 individuals.The exposure concentrations were verified by analytical measurements. The mortality of the fish was determined by visual observation after 24, 48, 72 and 96 hours.

The 96h-LC50 was determined to be 74 mg/L based on the boron element.

Description of key information

In the environment the transformation/hydrolysis of boron compounds is complex and is dependent on environmental factors; however, under typical aquatic environmental conditions it is expected that boric acid will be the most common and dominant species. Therefore, a read-across approach is considered appropriate to use a mixture of boric acid and borate compounds and other borate compounds as the source substance in the aquatic environment, rather than the target compound, calcium metaborate, refer to Section 13.

 

There are two weight of evidence read-across studies, which assess the acute toxicity to fish in freshwater and marine water. Due to the natural levels of boron in marine waters it is not expected that marine species will be more sensitive to boron toxicity than freshwater organisms, consequently both freshwater and marine species have been included. The freshwater study is used as part of a Species Sensitivity Distribution (SSD) method for derivation of the freshwater intermittent PNEC.

 

According to the ASTM E729-95B study guideline, a 96-hour freshwater LC50 value Pimephales promelas was determined to be 79.7 mg B/L (geometric mean), based on read-across from the source substance, a mixture of 82 % boric acid and 18 % borax.

 

A 96-hour marine LC50 of 74 mg B/L was identified in a standard toxicity testing method in fish, Limanda limanda, based on the read-across substance, disodium tetraborate.