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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002-05-14 - 2002-06-28
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study following GLP. The actual concentration of dissolved test material was not measured analytically.
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
CYANOX® 1790 Antioxidant
IUPAC nomenclature - Tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate
Synonym - [tris(4-t-butyl-3-hydroxy-2,6-dimethyl-benzyl)-s-triazine-2,4,6-(1H,3H,5H) trione]
Lot PA2010802
Appearance - White powder, odorless
CAS No. 40601-76-1
Molecular Formula - C42H57N3O6
Molecular Weight - 699.92 g/mole
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
Each of three replicates was spiked by direct addition of the test material (0.9 g) into 9 liters of dilution water. The replicate test chambers were placed onto mechanical stir plates with rotating stir bars. The test material was spiked directly into the vortex and allowed to mix for approximately 25 minutes. The liquid in each of the test chambers was then filtered through a Gelman minicapsule (0.45 microns) Versapore membrane filter. The test filtrate (which appeared clear) was transferred into glass test chambers
Test organisms (species):
Oncorhynchus mykiss (previous name: Salmo gairdneri)
Details on test organisms:
Juvenile rainbow trout (4.0 +/- 0.23 cm avg length and 0.8569 +/- 0.12 g average wet weight) were acclimated for 12 days before treatment. They were maintained in filtered laboratory freshwater at a temperature of 13.0 to 15.0 degrees C during the 12-day period prior to test initiation. They were fed a diet of salmon starter up to 24 hours before treatment. Mortality during the 7-day period prior to testing was 0%
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Post exposure observation period:
None
Hardness:
90 mg/l as calcium carbonate
Test temperature:
15 +/- 1 degrees C nominal. The temperature ranged from 14.2 - 14.6 degrees C during the test.
pH:
pH values ranged from 7.4 to 7.6 at the beginning of the test and were all 7.0 at the end of the test.
Dissolved oxygen:
The dissolved oxygen concentrations in the test water ranged from 10.4 to 10.6 mg/l (102-104 % of saturation) at the beginning of the test and 8.4 to 8.8 mg/l (82-86% of saturation) for the remainder of the test.
Salinity:
no data
Nominal and measured concentrations:
Range-finding test: 0.01, 0.1, 1.05, 10 and 100 mg wm/L
Definitive test: 100 mg/L
Details on test conditions:
The dilution water was a moderately hard freshwater, which originated from Jupiter Florida. It was treated by vigorous aeration, filtered to 20 microns, passed through activated carbon and re-aerated prior to use. The hardness (as calcium carbonate), alkalinity (as calcium carbonate) and specific conductivity were 90 mg/l, 31 mg/l and 377 microSiemens, respectively. Chemical characteristics were listed in an Appendix to the study.

A preliminary 96-hr range-finding test was conducted at nominal concentrations of 0.0 (control), 0.01, 0.10, 1.05, 10.0 and 100 mg whole material/l. Five fish were tested for each condition. None of the fish died in the experiment, and the material was insoluble at each concentration used.

Due to the insolubility of the test material in the preliminary test, the definitive test was initiated as a limit test with 100 mg whole material/l. Each of three replicates was spiked by direct addition of the test material (0.9 g) into 9 liters of dilution water. The replicate test chambers were placed onto mechanical stir plates with rotating stir bars. The test material was spiked directly into the vortex and allowed to mix for approximately 25 minutes. The liquid in each of the test chambers was then filtered through a Gelman minicapsule (0.45 microns) Versapore membrane filter. The test filtrate (which appeared clear) was transferred into glass test chambers, placed onto a 15 degrees C water table, and allowed to reach the desired test temperature (15 +/- 1 degrees C). Concurrent controls also were prepared in triplicate.

After initial water quality parameters (temperature, pH, dissolved oxygen) were measured, 7 fish (one or two at a time) were added to each test chamber (loading was 0.67 g fish/l). The test chambers were 10 liter glass tanks (43 cm x 23 cm x 14 cm) containing 9 liters of dilution water and providing a final water depth of 10 cm. All chambers were covered to reduce evaporation. The chambers were placed in a water bath and maintained under a photoperiod of 16 hours light/8 hours darkness (at 6-7 micromoles/m2/sec light intensity). Fish were not fed and water was not aerated during the test. Survival of fish and water quality were monitored daily. The test was terminated after 96-hr evaluations were performed.
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
LL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
NOELR
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
No mortality observed in the range-finding test.

None of the control or treated fish died or exhibited signs of toxicity. The No effect concentration (NOEL) and 96-hour LL50 values are therefore > 100 mg whole material/l.
Validity criteria fulfilled:
yes
Conclusions:
The test material was not toxic up to a nominal concentration of 100 mg/L.
Executive summary:

In a study conducted following OECD Guideline 203 and under GLP conditions, the test material was not toxic up to a nominal concentration of 100 mg/L. The 96-hour LC50 could not be calculated due to the lack of significant mortality at the specified time, and therefore can be stated to be > 100 mg/L. The no-observable-effect-concenration (NOEL) was 100 mg/L based on the lack of signification mortality and sublethal effects at this test concentration.

Description of key information

In a study conducted following OECD Guideline 203, the test material was not toxic up to a nominal concentration of 100 mg/L.

Key value for chemical safety assessment

LC50 for freshwater fish:
100 mg/L

Additional information

In an 96 -h acute aquatic toxicity study in juvenile rainbow trout, the test substance produced no mortality or signs of toxicity up to a highest dose of 100 mg/L (nominal).