Ammonium mercaptoacetate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 August 2004 - 22 October 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Version / remarks:

1992

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Duplicate samples and samples at 24 (fresh media), 48 and 72 hours (fresh and old media) were taken and stored at approximately -20°C for further analysis if necessary.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
For the purpose of the definitive test the test material was dissolved directly in dechlorinated tap water. The test material contains 71.2% as active ingredient (ai) and all test concentrations were corrected for this value.
An amount of test material (2810 mg) was dissolved in dechlorinated tap water and the volume adjusted to 20 litres to give the 100 mg ai/l test concentration. This method of preparation was conducted in duplicate to give replicates R; and R). Each of the stock solutions were inverted several times to ensure adequate mixing and homogeneity.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: rainbow trout
- Source: Brow Well Fisheries Limited, Hebden, UK
- Length at study initiation (length definition, mean, range and SD): 4.7 cm (sd = 0.2)
- Weight at study initiation (mean and range, SD): 1.34 g (sd= 0.31)
- Biomass loadign rate: 0.47 g bodyweight/litre.

ACCLIMATION
- Acclimation period: 13 d
- Acclimation conditions (same as test or not): same
- Feeding frequency during acclimation: stock fish were fed commercial trout pellets which was discontinued approximately 24 hours prior to the start of
the definitive test
- Health during acclimation (any mortality observed): no mortalities in the 7 days prior to the start of the test

FEEDING DURING TEST (as applicable)
- no

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Test temperature:

14°C

Details on test conditions:

TEST SYSTEM
- Test vessel: 20 litre glass vessels covered to reduce evaporation
- Aeration: yes, via narrow bore glass tubes
- Renewal rate of test solution (frequency/flow rate): daily renewal
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1


OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours darkness cycle with 20 minute dawn and dusk transition periods

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Any mortalities and sub-lethal effects of exposure were recorded at 3, 6, 24, 48, 72 and 96 hours after the start of exposure. The criteria of death were taken to be the absence of both respiratory movement and response to physical stimulation

Water temperature, pH and dissolved oxygen concentrations were recorded daily throughout the test.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: nominal test concentrations of 10 and 100 mg ai/l
There were no sub-lethal effects of exposure or mortalities during the range-finding test. Based on this information, a single test concentration, in duplicate, of 100 mg ai/l was selected for the definitive test. This experimental design conforms to a "Limit test" to confirm that at the maximum test concentration given in the OECD/EEC Test Guidelines, no mortalities or sub-lethal effects of exposure were observed.

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

There were no mortalities in 14 fish exposed to a test concentration of 100 mg ai/l for a period of 96 hours.
There were no sub-lethal effects of exposure observed in 14 fish exposed to a test concentration of 100 mg ai/I for a period of 96 hours.
Throughout the duration of the test the test preparations were observed to be clear colourless solutions.

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test material to the freshwater fish rainbow trout (Oncorhynchus mykiss) has been investigated and gave a 96-Hour LC50 of greater than 100 mg ai/l.

Executive summary:

This study was performed to assess the acute toxicity of the test material to rainbow trout (Oncorhynchus mykiss) in accordance with OECD TG 203 (1992).

Following a preliminary range-finding test fish were exposed, in two groups of seven, to an aqueous solution of the test material, at a single concentration of 100 mg active ingredient (ai)/l for a period of 96 hours at a temperature of approximately 14°C under semi-static test conditions. The number of mortalities and any sub-lethal effects of exposure in each test and control vessel were determined 3 and 6 hours after the start of exposure and then daily throughout the test until termination after 96 hours.

The 96-Hour LC50 based on nominal test concentrations was greater than 100 mg ai/l.
Data supplied by the Sponsor indicated that the test material, ammonium thioglycolate (ATG) was prone to oxidation to give diammonium dithiodiglycolate (DADTDG). Therefore analysis was performed to determine the concentration of both ATG and DADTDG.
The recovery analysis performed using test medium at room temperature showed the recovery rates for ATG and DADTDG to be 96% and 98% of fortification respectively. The stability analysis performed showed values for ATG to be 94% to 99% of the initial concentration after 24 hours. Analysis of the stability samples for DADTDG using test medium at room temperature showed concentrations between 7.7 and 9.5 mg/l after 24 hours. Given that the concentration of ATG was between 94% and 99% of initial concentration after 24 hours it was considered justifiable to perform the test using semi-static test conditions as opposed to dynamic, continuous flow test conditions.

Preliminary test samples were analysed for ATG at 0 and 24 hours. The results showed measured concentrations at 0 hours to be 96% and 99% of nominal and 99% and 102% of nominal after 24 hours.
Analysis of the test preparations for ATG at 0, 24 and 96 hours showed the measured concentrations to range between 96% to 102% of nominal. Analysis for DADTDG at 0 hours showed the concentrations to be 1.4 and 2.2 mg/l. However, after 24 hours concentrations of 2.9 and 3.0 mg/l of DADTDG were determined which were in-line with the stability analysis performed. The concentration of DADTDG in the 96-Hour test samples was not determined at the time point due to instrument malfunction but were analysed later when elevated levels of DADTDG were observed. Analysis of duplicate frozen samples showed elevated levels of DADTDG. However this was due to further degradation of the parent test material during the thawing process. It was however considered that the results would have been similar to the 24-Hour old test media result had the sample been analysed immediately.
Given that the measured concentrations of ATG were near nominal it was considered justifiable to estimate the results on nominal concentrations only.

Description of key information

96 h LC 50 >100 mg/L (OECD TG 203, Oncorhynchus mykiss, RL1, GLP)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

> 100 mg/L

Additional information

Experimental data on short-term toxicity to aquatic invertebrates are available for TGA, ATG and MeaTG.

 

TGA

The objective of this 96 hour study was to evaluate the acute toxicity of the test item to fish in accordance with OECD Guideline 203. For this purpose, juvenile Rainbow Trout were exposed in a flow-through test to aqueous test media containing the test item at the limit concentration of 100 mg/L (nominal). The recorded effects were mortality and symptoms of intoxication of the test fish. 7 fish were exposed for 96 hours to thioglycolic acid.

Based on the test results the 96 hour LC50 of Thioglycolic Acid for Oncorhynchus mykiss was determined to be higher than 100 mg test item/L based on nominal concentration.

 

The acute toxicity to Oryzias latipes (Japanese Medaka) has been investigated in a study according to OECD Guideline 203 (1992) under semi-static conditions with daily renewal of the test solutions. 10 fish/concentration were exposed to the test item for 96 hours at concentrations of 9.5 mg/L, 17.1 mg/L, 30.9 mg/L, 55.6 mg/L, and 100.0 mg/L and one pH-adjusted (neutralized) concentration of 100.0 mg/L.

Concentrations were based on a pre-test, in which preliminary results showed a 96 h LC50 of 55.9 mg/L, a 0% lethal maximum concentration of 25 mg/L, and a 100% lethal minimum concentration of 125 mg/L. 

Because the measured concentration deviated from the set concentration by ± 20%, the geometric mean of the measured concentration was used to calculate the test results.

Mortality rate of fish exposed to mercaptoacetic acid for 96 hours was 0% in the lowest concentration of 5.9 mg/L and 100% in the highest concentration of 102.5 mg/L. The mortality rate in the control was 0%. The mortality rate in the pH-adjusted (neutralized) test solution was 10%.

Abnormal swimming was observed in the concentration of 56.3 mg/L as a toxic symptom. No abnormal symptoms were observed during the test in the control and other concentrations. Based on the test results the 96 hour LC50 of the test item was 39.8 mg/L, and its 95% confidence interval was 28.1 mg/L to 56.3 mg/L and in the pH adjusted (neutralized) test solution was > 74.8 mg/L (geom. Mean; corresponding to > 100 mg/L nominal).

Since the pH was in the range of 3.4-4.0 at the two highest concentration levels, the result with the neutralised pH is considered to be more relevant, which is also in line with the test conducted in rainbow trout.

 

ATG

This study was performed to assess the acute toxicity of the test material to rainbow trout (Oncorhynchus mykiss) in accordance with OECD TG 203 (1992).

Following a preliminary range-finding test fish were exposed, in two groups of seven, to an aqueous solution of the test material, at a single concentration of 100 mg active ingredient (ai)/l for a period of 96 hours at a temperature of approximately 14°C under semi-static test conditions. The number of mortalities and any sub-lethal effects of exposure in each test and control vessel were determined 3 and 6 hours after the start of exposure and then daily throughout the test until termination after 96 hours.

The 96-Hour LC50 based on nominal test concentrations was greater than 100 mg ai/l.
Data supplied by the Sponsor indicated that the test material, ammonium thioglycolate (ATG) was prone to oxidation to give diammonium dithiodiglycolate (DADTDG). Therefore analysis was performed to determine the concentration of both ATG and DADTDG.
The recovery analysis performed using test medium at room temperature showed the recovery rates for ATG and DADTDG to be 96% and 98% of fortification respectively. The stability analysis performed showed values for ATG to be 94% to 99% of the initial concentration after 24 hours. Analysis of the stability samples for DADTDG using test medium at room temperature showed concentrations between 7.7 and 9.5 mg/l after 24 hours. Given that the concentration of ATG was between 94% and 99% of initial concentration after 24 hours it was considered justifiable to perform the test using semi-static test conditions as opposed to dynamic, continuous flow test conditions.

Preliminary test samples were analysed for ATG at 0 and 24 hours. The results showed measured concentrations at 0 hours to be 96% and 99% of nominal and 99% and 102% of nominal after 24 hours.
Analysis of the test preparations for ATG at 0, 24 and 96 hours showed the measured concentrations to range between 96% to 102% of nominal. Analysis for DADTDG at 0 hours showed the concentrations to be 1.4 and 2.2 mg/l. However, after 24 hours concentrations of 2.9 and 3.0 mg/l of DADTDG were determined which were in-line with the stability analysis performed. The concentration of DADTDG in the 96-Hour test samples was not determined at the time point due to instrument malfunction but were analysed later when elevated levels of DADTDG were observed. Analysis of duplicate frozen samples showed elevated levels of DADTDG. However this was due to further degradation of the parent test material during the thawing process. It was however considered that the results would have been similar to the 24-Hour old test media result had the sample been analysed immediately.
Given that the measured concentrations of ATG were near nominal it was considered justifiable to estimate the results on nominal concentrations only.

 

MeaTG

A study was performed to assess the acute toxicity of the test material to rainbow trout (Oncorhynchus mykiss). The method followed that described in the OECD Guidelines for Testing of Chemicals (1992) No 203, "Fish, Acute Toxicity Test" referenced as Method C.1 of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).
Following a preliminary range-finding test, fish were exposed, in two groups of seven, to an aqueous solution of the test material, at a single concentration of 100 mg active ingredient (ai)/l for a period of 96 hours at a temperature of approximately 14°C under dynamic, continuous flow test conditions. The number of mortalities and any sub-lethal effects of exposure in each test and control vessel were determined 3 and 6 hours after the start of exposure and then daily throughout the test until termination after 96 hours.
The 96-Hour LCs9 based on nominal test concentrations was greater than 100 mg ai/l and correspondingly the No Observed Effect Concentration was 100 mg ai/I.
The test material was known to oxidise, when diluted to very low concentrations in oxygenated water, to give dimonoethanolamine dithiodiglycolate (DiMEADTDG). As the analysis was carried out under acid conditions, the DIMEADTDG was converted to dithiodiglycolic acid (DTDGA) and MEATG was converted to thioglycolic acid (TGA). Therefore, all test preparations were analysed for TGA (calculated as MEATG) and DTDGA (used as a marker for DiMEADTDG).
Analysis of the test preparations at 0, 24, 48, 72 and 96 hours showed measured test concentrations of MEATG to range from 96% to 114% of nominal and measured concentrations of DTDGA of 2.41 to 3.76 mg/l. Given that the measured concentrations of the parent test material MEATG were within the 80% to 120% acceptance limits, it was considered justifiable to base the results on nominal test concentrations only.

 

Conclusion

In the available short-term toxicity studies, the examined substances were not toxic to fish up to and including the limit concentration of 100 mg/L. The 96 h LC50 for all substances within this category is >100 mg/L.