Diarsenic trioxide

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

no guideline available

Principles of method if other than guideline:

48-h acute toxicity test with Daphnia magna

GLP compliance:

not specified

Specific details on test material used for the study:

Purity: reagent grade
NaAsO2

Analytical monitoring:

yes

Details on sampling:

Samples were taken at 0, 48, and 96 hr for the daphnid acute toxicity tests.
Five mL samples of exposure water and 50mL of control tank water were collected and diluted to near 100mL with deionized water. Before final volume adjustment, samples were acidified(1%HNO3,v/v) and fortified with 0.6% hydrogenperoxide (H202, v/v) and 0.1% nickel nitrate hexahydrate (Ni(NO3)z-6H20, w/v). Sample digestion was omitted.

Vehicle:

no

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnids were also obtained from Environmental Research Laboratory-Duluth (ERL-D), Duluth, MN stock culture.
Life stage: < 24h neonates
They were rearedin 25°C Lake Superior water and fed a mixture of ground trout pellets and yeast(ASTM 1980).
The food mixture was prepared by homogenizing 60 g of fish food pelletswith 1.5 g of bread-makers yeast in water.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

46.3-49.9 mg/L CaCO3

Test temperature:

15.6 °C

pH:

7.2-8.1

Dissolved oxygen:

79.6-99.3%

Nominal and measured concentrations:

0.815, 1.08, 1.86, 2.44, 4.19 and 6.46 mg As/L (<0.002 mg As/L in control)
Test concentration were analytically confirmed.

Details on test conditions:

An acute toxicity test with As and daphnids were completed at the UW-Superior laboratory without food added.
The exposure chambers were 250mL beakers containing 200 mL of the toxicant solution.
Six exposure concentrations and controls were prepared in duplicate for the unfed and fed tests.
The chambers were placed in a temperature controlled water bath and five daphnids,<24 hr old, were placed in each chamber.

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

1.5 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Remarks:

As

Basis for effect:

mortality

Remarks on result:

other: 95% confidence interval: 1.17 - 1.94 mg As/L

Reported statistics and error estimates:

Trimmed Spearman-Karbemr method

Conclusions:

The short-term 48 hours LC50 value reported for freshwater invertabrate is 1.500 mg As/L for the mortality of Daphnia magna.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

according to guideline

Guideline:

other: ASTM 1980. Standard practice for conducting acute toxicity tests with fishes, macroinvertebrates and amphibians

Principles of method if other than guideline:

short-term toxicity test to Opossum shrimp

GLP compliance:

not specified

Analytical monitoring:

yes

Test organisms (species):

Americamysis bahia (previous name: Mysidopsis bahia)

Test type:

flow-through

Water media type:

saltwater

Total exposure duration:

96 h

Test temperature:

20-25 °C

pH:

7.8-8.2

Salinity:

30 ppt

Nominal and measured concentrations:

Test concentrations were analytically confirmed.

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

1.74 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element (dissolved fraction)

Remarks:

As

Basis for effect:

mortality

Remarks on result:

other: 95% confidence limits: 1.39 - 2.26 mg As/L

Conclusions:

The 96-h LC50 for survival of the marine invertebrate Americamysis bahia is 1.74 mg As/L.

Description of key information

Six reliable data points were retained for acute toxicity of As to freshwater invertebrates, covering four different invertebrates (i.e. the crustaceans C. dubia, D. magna, D. pulex and G. pseudolimnaeus). L(E)C₅₀ values range between 1448 and 11900 µg As/L. The lowest value of 1448 µg As/L was observed for C. dubia, whereas the geometric mean value of the three data points for C. dubia was 1579 µg As/L. The lowest species mean 48 -h LC₅₀ value for D. magna of 1500 µg As/L is put forward for classification purposes.

In addition, one reliable datapoint was identified for a standard test with the marine opossum shrimp Americamysis bahia with a reported 96-h LC₅₀value of 1740 µg As/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1.5 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

1.74 mg/L