Triboron trimethyl hexaoxide

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:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test procedures in accordance with accepted standard methods. Although not conducted according to GLP guidelines it is sufficiently documented and acceptable for assessment

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: EPA-660/3-75-009, 1975

Principles of method if other than guideline:

Test procedures followed the basic flow-through test method described by the U. S. Environmental Protection Agency (EPA-660/3-75-009, 1975)

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

Water for all tests was untreated and obtained directly from Lake Superior and heated to mean test temperature.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

TEST ORGANISM
- Common name: bluegill
- Source: Lake Mills Fish Hatchery, Lake Mills, WI, USA
- Weight at study initiation (mean and range, SD): Average weights of exposed fish were obtained by weighing control fish from each test. Average weight of bluegills was 3.07 ± 1.38 g

- Feeding during test: Fish were not fed 24 h before or during a test

- holding before 24 h before test: at respective test temperature and fed a commercial formulation of dry food.

Test type:

flow-through

Water media type:

freshwater

Total exposure duration:

96 h

Hardness:

46.6 mg/L CaCO3 (40.4 - 56.3)

Test temperature:

19.8 ± 2.3 °C

pH:

7.04 - 7.97

Dissolved oxygen:

78.8 % (54.3 - 88.9)

Nominal and measured concentrations:

five test concentrations and a control

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 530-L fiberglass holding tanks
- Type of flow-through (e.g. peristaltic or proportional diluter): The exposure system for fish consisted of several modified proportional diluters with dilution factors ranging from 0.6 to 0.8. Each diluter cycle delivered 1.0 L of water and toxicant, where appropriate, to each of five test concentrations and a control. Each test concentration and control was duplicated by dividing the original volume equally using flow-splitting tanks. The glass exposure tanks contained 6.3 L water. Diluters were cycled at a rate to yield 5 to 8 tank volumes/day.

- No. of organisms per vessel: 10

TEST MEDIUM / WATER PARAMETERS
- Alkalinity: 41.7 mg/L CaCO3 (30.0 - 46.0)
- Mean dissolved oxygen: 78.8 % (54.3 - 88.9)

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

15 400 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 13500-17600

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

12 700 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95% CL: 11800-13700

Reference 2

Endpoint:

short-term toxicity to fish

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: Guideline study; well performed study

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

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 3

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study meets generally accepted scientific standards, well documented and acceptable for assessment

Principles of method if other than guideline:

No particular guideline has been followed, however the test method has been described in detail within the publication.

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

not specified

Test organisms (species):

other: Trachinotus carolinus

Details on test organisms:

- Test fish: Florida pompano
- Origin: Port Fourchon Beach and Isle Dernieres, Louisiana
- Individual body mass at time of capture: 2.0 - 16.0 g

HOLDING
- Acclimation: Fish were held for at least 4 weeks in a 5000 L recirculating seawater system at 30 practical salinity units (psu)
- Medical treatment: during quarantine, fish were treated with 0.2 mg/L copper to eliminate ectoparasites
- Feeding: fish were fed commercially produced feed except within the 17 h before and during acute toxicity testing
- Holding system: system was constantly aerated and water parameters (pH, salinity, ammonia level) were monitored several times a week
- AmQuel (HOCH2SO3Na) was added to holding system to reduce the ammonia level when it exceeded 0.5 mg/L

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

24 h

Test temperature:

25°C

Salinity:

30 psu

Nominal and measured concentrations:

- Concentrations tested (nominal): 0.99%, 1.07%, 1.17%, 1.27%, 1.38% and 1.51% methanol plus control
- Concentrations tested (measured): 0.99%. 1.13%, 1.22%, 1.36%, 1.46% and 1.49% methanol plus control

Details on test conditions:

TEST SYSTEM
- Test vessel: conical fiberglass tanks filled with ultraviolet(UV)-sterilized, 30-psu seawater and covered with clear acrylic lids to reduce volatilization
- Test volume: 70 L
- Aeration: yes
- No. of fish / concentration: 10

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

10 112 mg/L

Conc. based on:

test mat.

Details on results:

1.28% v/v = 12.8 ml
12.8 ml * 0.79 g/ml = 10112 mg/L

Reference 4

Endpoint:

short-term toxicity to fish

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: Peer reviewed study

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)

LC50 after 48h : 75.7 (68.0 - 85.0)

LC50 after 72h : 75.7 (68.0 - 85.0)

Description of key information

TMBX is hydrolytically unstable and breaks down to form methanol and boric acid in the presence of water, these species can be expected to be found folllowing release to the environment. Therefore, an assessment of ecotoxicological potential was conducted taking account of the effects of the hydrolysis breakdown products of TMBX upon the different trophic levels.

Acute (96hr) Methanol toxicity was examined in Bluegill fish Lepomis macrochirus in a flow through fresh water system (Poirer et al 1986), the LC50 was calculated to be 15400 mg/L (13500-17600 95% CL) and the EC50 derived as 12700mg/L (11800-13700 95% CL).

Testing of boric acid/Disodium tetraborate in Fathead minnow (Pimephales promelas) in a 96 hour static freshwater system (Soucek et al 2010) resulted in a LC50 of 79.7 mg /L ( 95% CI: 72-88 mg/L) based on elemental Boron.

The 24 hour toxicity of methanol to Florida Pompano (Trachinotus carolinus) was determined in a static seawater system (Baltz et al 2005), the LC50 was determined to be 10112 mg/L.

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 (Taylor et al, 1985). No standard guideline was identified, but methods were equivalent to standard fish toxicity testing methods. The LC50 was determined to be 74mg/L based on elemental Boron ( 95% CI 66.4-83 mg/L).

Based on the above results, the EC50 values for boron were used to calculate equivalent values for TMBX:

Freshwater 96 hr LC50 = 79.7 x (173.5/32.4) =426.8 mg/L

Seawater 96 hr LC50 = 74 x (173.5/32.4) = 396.3 mg/L

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

426.8 mg/L

Marine water fish

Marine water fish

Effect concentration:

396.3 mg/L