Diarsenic trioxide

Sediment toxicity

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

sediment toxicity: short-term

Remarks:

14 d study endpoints survival autotomy

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

ASTM E1706 (Standard Test Method for Measuring the Toxicity of Sediment-Associated Contaminants with Freshwater Invertebrate

Deviations:

yes

Remarks:

Adapted from ASTM guideline

Principles of method if other than guideline:

14 days spiked sediment test with Tubifex tubifex

GLP compliance:

not specified

Specific details on test material used for the study:

Na2HAsO4. 7H20 but concentrations expressed as elemental As.

Analytical monitoring:

yes

Remarks:

ICP-AES

Details on sampling:

Metal concentrations were analyzed from the replicate used for chemical analysis The whole sediment sample was dried at ambient temperature, sieved through a 0.063 mm mesh before digestion.

Vehicle:

no

Details on sediment and application:

Natural sediment was used from Barrundia (Spain). Organic matter content 1.7 %, 49 % gravel, 39% sand and 4 % clay.

Test organisms (species):

Tubifex tubifex

Details on test organisms:

6-7 weeks old (sexually mature)

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

14 d

Exposure phase:

total exposure duration

Hardness:

not reported

Test temperature:

22°C

pH:

7.9 mg/L

Dissolved oxygen:

7.6 mg/L

Salinity:

not reported

Ammonia:

1.5 mg/L

Conductivity:

310 µS/cm-1

Nominal and measured concentrations:

0, 3.2, 10, 31.6, 100, 316(nominal); 12, 29, 44, 95, 208, 421 (measured)

Details on test conditions:

Test containers contained 100 mL sediment and 100 mL dilution water. For each of the five test concentrations 3 replicates were prepared. One replicate for the chemical analysis at the start of the toxicity tests and the other replcates were used for the effects assessment. Static test design. Temperature 22 °C.

Reference substance (positive control):

no

Key result

Duration:

14 d

Dose descriptor:

EC10

Effect conc.:

80.98 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

other: autotomy

Duration:

14 d

Dose descriptor:

EC50

Effect conc.:

210 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

other: Autotomy

Duration:

14 d

Dose descriptor:

LC10

Effect conc.:

116 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

251 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Reported statistics and error estimates:

Statistical analyses were conducted using the measured test concentrations. Two-parameter log-logistic (LL.2) regression models were used to calculate the effective and lethal concentrations (EC10, EC50, LC10, and LC50). Significant differences with controls were assessed by Fisher’s exact test. Significance level was α = 0.05.

Validity criteria fulfilled:

yes

Conclusions:

Lethal and sublethal (autotomy) effects were observed after 14 d exposure of the worm Tubifex tubifex to arsenic. The most sensitive endpoint was autotomy which yielded an EC10 value of 80.98 mg As/kg dw. Mortality was less sensitive with an LC 10 value of 116 mg As/kg dw.

Reference 2

Endpoint:

sediment toxicity: short-term

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:

according to guideline

Guideline:

other: Environment Canada guideline

GLP compliance:

not specified

Specific details on test material used for the study:

NaAsO2 but results expressed as elemental Arsenic

Analytical monitoring:

yes

Details on sampling:

Approximately 2g of wet sediment from the top 2cm layer were collected from three beakers per treatment on day 0 (priortotheadditionofanimals)with awide-tipped Pipet and placed directly in pre-cleaned bottles. Samples were dried at 60 °C for 96h.Sediments amples were also collected from threed ifferentb eakers on day10, and samples placed in clean glass petriplates for thorough examination for tes torganisms before drying the sediment for total metals analysis.

Vehicle:

no

Details on sediment and application:

Natural sediment Wollaston lake. Not contaminated collected in 1998; High TOC 7.4 % and AVS content of 1.7 µmol.g dw, clay 18.8 %, sand 57.1 %, Fe-oxide 23077 g/kg, background As 2.4 mg As/kg dw

Test organisms (species):

Hyalella azteca

Details on test organisms:

7-14 days old juveniles

Study type:

laboratory study

Test type:

flow-through

Water media type:

freshwater

Type of sediment:

natural sediment

Remarks:

High TOC 7.4 % and AVS content of 1.7 µmol.gdw

Limit test:

no

Duration:

10 d

Exposure phase:

total exposure duration

Hardness:

112 mg/L CaCO3

Test temperature:

22.6-22.8

pH:

8.2

Dissolved oxygen:

7.8

Salinity:

not reported

Ammonia:

0.05 mg/L

Conductivity:

Total chlorine < 0.1 mg/L

Nominal and measured concentrations:

Concentration range not given

Details on test conditions:

Tests were run in a flow through system. Test bekers of 300 mL were used and contained 100 mL of sediment. During the 10d experiment each beaker received 6 mg of Tetramin slurry daily. Six replicates per concentration. Equilibration time before test initiation was 20 days.

Reference substance (positive control):

no

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

462 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Remarks:

and growth

Duration:

10 d

Dose descriptor:

LOEC

Effect conc.:

724 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Remarks:

and growth

Duration:

10 d

Dose descriptor:

LC50

Effect conc.:

532 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Duration:

10 d

Dose descriptor:

other: LC25

Effect conc.:

521 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Reported statistics and error estimates:

All LC50 data were calculated using the model Spearman– Karber method. .LC25s were estimated by linear interpolation. No-observed-effectconcentrations( NOECs) and lowest-observed-effect concentrations (LOECs) were calculated by one-way analysis of
variance (ANOVA) followed byaTukey multiple comparison test(0.05) using SigmaStat.

Validity criteria fulfilled:

yes

Conclusions:

A NOEC of 462 and a LOEC of 724 mg As/L have been observed for the endpoint mortality of Hyalella azteca. Dose-repsonse curves were not reported but are quite steep as LC50 and LC25 values are close to eachother (532 and 521 mg As/kg dw, respectively. For the growth endpoint the dose -response data were reported to be inadequate.

Reference 3

Endpoint:

sediment toxicity: short-term

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:

according to guideline

Guideline:

other: Environment Canada guideline

GLP compliance:

not specified

Specific details on test material used for the study:

NaAsO2 but results expressed as elemental Arsenic

Analytical monitoring:

yes

Details on sampling:

Approximately 2g of wet sediment from the top 2cm layer were collected from three beakers per treatment on day 0 (priortotheadditionofanimals)with awide-tipped Pipet and placed directly in pre-cleaned bottles. Samples were dried at 60 °C for 96h.Sediments amples were also collected from threed ifferentb eakers on day10, and samples placed in clean
glass petriplates for thorough examination for tes torganisms before drying the sediment for total metals analysis.

Vehicle:

no

Details on sediment and application:

Natural sediment Wollaston lake. Not contaminated collected in 1998; High TOC 7.4 % and AVS content of 1.7 µmol.g dw, clay 18.8 %, sand 57.1 %, Fe-oxide 23077 g/kg, background As 2.4 mg As/kg dw

Test organisms (species):

Chironomus dilutus (previous name: Chironomus tentans)

Details on test organisms:

8 days old larvae

Study type:

laboratory study

Test type:

flow-through

Water media type:

freshwater

Type of sediment:

natural sediment

Remarks:

High TOC 7.4 % and AVS content of 1.7 µmol.gdw

Limit test:

no

Duration:

10 d

Exposure phase:

total exposure duration

Hardness:

112 mg/L CaCO3

Test temperature:

22.6-22.8

pH:

8.2

Dissolved oxygen:

7.8

Salinity:

not reported

Ammonia:

0.05 mg/L

Conductivity:

Total chlorine < 0.1 mg/L

Nominal and measured concentrations:

Conentration range not given

Details on test conditions:

Tests were run in a flow through system. Test bekers of 300 mL were used and contained 100 mL of sediment. During the 10d experiment each beaker received 6 mg of Tetramin slurry daily. Six replicates per concnetration.

Reference substance (positive control):

no

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

39 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Duration:

10 d

Dose descriptor:

LOEC

Effect conc.:

116 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Duration:

10 d

Dose descriptor:

LC50

Effect conc.:

642 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Duration:

10 d

Dose descriptor:

other: LC25

Effect conc.:

675 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Remarks on result:

other: LC25 higher than LC50. Unreliable

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

< 39 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

biomass

Remarks:

growth

Duration:

10 d

Dose descriptor:

LOEC

Effect conc.:

<= 39 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

biomass

Remarks:

growth

Remarks on result:

other: 11 % effect at LOEC

Duration:

10 d

Dose descriptor:

EC50

Effect conc.:

342 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

biomass

Remarks:

growth

Duration:

10 d

Dose descriptor:

other: EC25

Effect conc.:

174 mg/kg sediment dw

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

biomass

Remarks:

growth

Reported statistics and error estimates:

All LC50 data were calculated using the model Spearman– Karber method. .LC25s were estimated by linear interpolation. No-observed-effectconcentrations( NOECs) and lowest-observed-effect concentrations (LOECs) were calculated by one-way analysis of variance (ANOVA) followed byaTukey multiple comparison test(0.05) using SigmaStat.

Validity criteria fulfilled:

yes

Conclusions:

The lowest value obtained for the effect of NaAsO2 on Chironomus dilutus is an unbounded LOEC of 39 mg As/kg dw for the growth endpoint. At the LOEC of 39 mg As/kg dw 11 % effect is observed so this can be taken as the true EC10 value. The growth endpoint was much more sensitive than the mortality endpoint wit a NOEC based on mortality of 642 mg As/kg dw versus < 39 mg As/kg dw for growth.

Reference 4

Endpoint:

sediment toxicity: short-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

14 days

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Remarks:

Environment Canada EPS 1/RM/33

Qualifier:

according to guideline

Guideline:

other: Environment Canada EPS 1/RM/33

Deviations:

no

GLP compliance:

not specified

Specific details on test material used for the study:

NaAsO2 but results expressed as elemental Arsenic

Analytical monitoring:

yes

Details on sampling:

Concentrations of As were measured at the end of the toxicity tests in all sediment treatments for both juveniles and adults). Sediment samples were thoroughly mixed, and 20 g were transferred to weighing dishes. Then, samples were weighed, and the wet weight was recorded.
Sediment samples were then dried to a constant weight at 60 8C. To achieve homogeneity, dried samples were sieved using a 5-mesh polypropylene sieve and ground in a mortar and pestle. Dried, ground sediment samples were weighed accurately, and a representative 1.00.01 g aliquot of the sample was weighed and transferred to a 250-mL glass beaker for acid extraction.
Samples were digested in solutions containing 2mL of concentrated HNO3 and 2mL of concentrated HCl diluted to 14mL with deionized water and covered with a glass lid Beakers were then placed on a hot plate in a fume hood at a temperature of approximately 95 8C for 30 min. Extracted samples were transferred into a 100-mL amber glass and stored at 4 8C until analysis.

Vehicle:

no

Details on sediment and application:

Natural sediment Lake St. François. Background As < 4-5 mg As/kg dw. Organic carbon content not reported

Test organisms (species):

Hyalella azteca

Details on test organisms:

Tests were conducted both with adults (> 21d) and juveniles (2-9d)

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

natural sediment

Remarks:

Natural sediment Lake St. François. Background As < 4-5 mg As/kg dw.. Organic carbon content not reported

Limit test:

no

Duration:

14 d

Exposure phase:

total exposure duration

Hardness:

105-366 mg CaCO3/L for tests with adults
144-270 mg CaCO3/L for tests with juveniles

Test temperature:

19.8-23.2 °C for tests with adults
20.8-24.0 °C for tests with juveniles

pH:

7.14-8.91 for tests with adults
7.99-8.71 for tests with juveniles

Dissolved oxygen:

not reported

Salinity:

not reported

Ammonia:

not reported

Conductivity:

not reporter

Nominal and measured concentrations:

0-20-40-77-145 and 324 (nominal)

Details on test conditions:

1L glass jars with 200 mL spiked sediment and 350 mL overlying water. Static tests, feeding 3 times a week. 5 replicates per concentration. Temperature 20-24 °C. spiking in pore water and then mixed used wet sediment rolling. Equilibration time was 8 weeks. No renewal of the overlying water. Arsenic levels in the overlying water were 250 µg/L after 2wk and 200 µg/L after 4 wk.

Reference substance (positive control):

no

Duration:

14 d

Dose descriptor:

LC50

Remarks:

Adults

Effect conc.:

165 mg/kg sediment dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Remarks on result:

other: LC50 based on As in water: 1198 µg As/L

Duration:

14 d

Dose descriptor:

other: LC20

Remarks:

Adults

Effect conc.:

45 mg/kg sediment dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Remarks on result:

other: LC20 based on As in water: <23 µg As/L

Duration:

14 d

Dose descriptor:

other: EC20

Remarks:

Adults

Effect conc.:

239 mg/kg sediment dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

biomass

Remarks:

growth

Remarks on result:

other: EC20 based on As in water: 973 µg As/L

Duration:

14 d

Dose descriptor:

LC50

Remarks:

Juveniles

Effect conc.:

134 mg/kg sediment dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Remarks on result:

other: LC50 based on As in water: 899 µg As/L

Duration:

14 d

Dose descriptor:

other: LC20

Remarks:

Juveniles

Effect conc.:

< 23 mg/kg sediment dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element (total fraction)

Remarks:

As

Basis for effect:

mortality

Remarks on result:

other: LC20 based on As in water: <23 µg As/L

Reported statistics and error estimates:

Statistical analysis for both growth and survival was performed using TOXSTAT. The statistical analyses used to determine if growth and survival for each metal were different from the control were the nonparametric Tukey test and the nonparametric Steel’s many-one rank test, respectively.

Validity criteria fulfilled:

not specified

Conclusions:

Arsenic was less toxic to adult H. azteca than to juveniles, with an LC50 values of 165 mg As/kg dry weight for adults in comparison with LC50 values of 135 mg As/kg dry weight for juveniles. The LC20 values exhibited a similar pattern. The lowest value observed was an LC20 <23 mg As/kg dw.

Description of key information

No chronic sediment toxicity tests could be identified. Only three reliable (Klimisch 2) acute/sub-acute freshwater sediment tests were identified for three species: Tubifex tubifex (14d EC10 autotomy: 81 mg As/ kg dw, Lobo et al, 2016); Hyalella azteca (10 d NOEC survival: 462 mg As/kg dw, high organic carbon content, Liber et al, 2011; LC20 <23 and 45 mg As/kg dw for juveniles and adults, respectively, Goulet et al., 2018); and Chironomus dilutus (EC10 survival: 116 mg As/kg dw and EC10 growth: 39 mg As/kg dw, Liber et al, 2011).

Additional information

The number of available and relevant sediment toxicity data for arsenic is scanty. No chronic sediment toxicity tests could be identified. Only three reliable (Klimisch 2) acute/sub-acute freshwater sediment tests were identified for three species: Tubifex tubifex (14d EC10 autotomy: 81 mg As/ kg dw, Lobo et al, 2016); Hyalella azteca (10 d NOEC survival: 462 mg As/kg dw, high organic carbon content, Liber et al, 2011; LC20 <23 and 45 mg As/kg dw for juveniles and adults, respectively, Goulet et al., 2018); and Chironomus dilutus (EC10 survival: 116 mg As/kg dw and EC10 growth: 39 mg As/kg dw, Liber et al, 2011).

According to ECHA Guidance on information requirements and chemical safety assessment (Chapter R.10.5.2.2 an assessment factor of 1,000 is applicable to the lowest value of acute sediments tests. This would yield a PNEC for freshwater sediment ranging from 0.023 - 0.081 mg As/kg dw. This is 74 to 260 times below the median natural background of 6 mg As/kg dw as reported by the FOREGS database and even up to a factor of almost 1000 below the reported 90^th percentile for As background concentration in sediment of 22 mg As/kg dw.

In the case of having only acute data the PNEC_sed should also be calculated from the PNEC_water using the equilibrium partitioning method. With a PNEC_water of 5.6 µg As/L (freshwater) and 4.7 µg As/L (marine) this would give a PNEC_sed,EqP  of 70.5 and 35.9 mg As/kg dw for freshwater and marine sediments, respectively. These values are in the range of the actual lower no observed effect data (23-81 mg/kg dw) of the acute whole sediment toxicity test data. It must be noted that the spiking procedures used in these acute toxicity tests resulted in higher As concentrations in overlying water and pore water than what would be expected under field conditions. Therefore, these results can be considered as overly conservative.

In the absence of chronic whole sediment toxicity tests the EqP-derived sediment PNEC should be used for screening purposes.