Guanidinium thiocyanate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For justification for read-across applying the analogue approach please refer to attached document in Chapter 13.2 "other assessment reports".

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1.94 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other: NOEC calculated from key result of source based on molecular weigth of target substance

Details on results:

Based on the read-across source Ammonium thiocyanate the NOEC is calculated to be 1.94 mg/l based on molecular weight of Guanidine thiocyanate.

Conclusions:

The strong points of this study are that 1) the study was conducted following OECD guidelines, 2) under GLP, and 3) that there was analytical monitoring of the concentration of ammonium thiocyanate during the study. The weak points mainly relate to the lack of provision of information on the results of a test with a reference compound. However, this would not prevent the reproduction of the test.

Based on the results of this study, the 21-d NOEC is 1.25 mg/L and the 21-d EC50 for reproduction is 2.6 mg/L.

Executive summary:

The purpose of this study was to assess the toxicity of ammonium thiocyanate dissolved in fresh water, on the reproductive efficacy ofDaphnia magna STRAUS - clone 5, in a 21-day semi-static test complying with the OECD Guideline No. 211, September 21 1998 and EU guideline C.20 from Annex V of Directive 67/548/EEC. 

 

The test criterion of toxicity used was reproductive capacity expressed as the number of neonates per daphnid per day.

 

The nominal concentrations used in the study were as follows: 0, 0.6, 1.25, 2.5, 5 and 10 mg/I

 

Analytical determinations of the test solutions were made on six occasions during the test. The concentrations were found to remain stable to within±20% of the nominals. The nominal concentrations were used to calculate the effect concentrations.

 

The validity criteria were respected:

Less than 20% mortality occurred in the control group over the test period.

The average number of juveniles per parent in the control was greater than 60 per surviving parent daphnid (average = 92.8) after 21 days.

 

The 21 d EC50s for adult mortality and for reproduction were determined as 3.8 mg/I and 2.6 mg/I, respectively.

 

The No Observed Effect Concentration (NOEC) is determined as the concentration used in the study that is immediately below the Lowest Observed Effect Concentration (LOEC), the latter derived statistically from the data using the appropriate statistical test.

 

Data were found to be normally distributed and homogeneous. Using Dunnett's and Bonferroni-t tests, the Lowest Observed Effect Concentration (LOEC) based on reproductive output, and on parent body length were found to be 2.5 mg/1. The lowest Observed Effect Concentration (LOEC) based on weight of adult daphnids was 5 mg/1.

 

Based on these statistical results, the lowest NOEC is 1.25 mg/L

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2004-08-11 to 2004-09-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Test substance, project sample code is T 04006, supplied by Akzo Nobel CARBOSULF Chemische Werke GmbH. Data on the handling, stability, composition, purity or other characteristics of the test substance supplied has been used without further verification. The analytical certificate is included together with the attached study report.

Chemical name: AMMONIUM THIOCYANATE
CAS reg. no: 1762-95-4
Purity: 99.9%
Appearance: White crystals
Stability: Stable under test conditions
Expiry date: 01.01.06
Storage until required: At room temperature in a hermetically sealed container
Water solubility: >100 g/l at 20°C and pH7
Vapour pressure: <100 Pa at 20°C


Analytical certificate included in report

Analytical monitoring:

yes

Details on sampling:

Samples were taken on the first day of the study on preparation and just before changing (same solution). Further samples were taken weekly thereafter following the same procedure. Samples were frozen until analysis. The volume of the samples was 50 ml. All samples were taken in duplicate.

Vehicle:

no

Details on test solutions:

Preparation of the stock solutions
Approximately 0.1 g of test substance was dissolved directly in 100 ml of M4 medium by mechanical agitation for up to 3 h in order to completely dissolve the test substance. The pH of each stock solution was checked and found to be between 6.9 and 7.2. The pH was adjusted to between 7.7 and 7.8 with 1 M NaOH (reagent grade). A fresh stock solution was prepared for each solution change.

Preparation of the test solutions
Test solutions were prepared by further dilution of the stock solution with M4. A geometric series of concentrations were used. The ratio between two consecutive concentrations was approximately 2. Test vessels were filled directly from the test solution containers immediately after preparation. The solutions were renewed at least three times a week during the test. One control containing only test medium was included in the test.

Test organisms (species):

Daphnia magna

Details on test organisms:

The test animals were taken from a Daphnia magna clone 5 stock, (origin: Notox b.v.,Hambakenwetering 7, P.O. Box 3476, 5203 DL 's-Hertogenbosch.The Netherlands). The animals used in the test were less than 24 hours old and were obtained from parent animals reproducing parthenogenically and having an age of 2-4 weeks (having previously produced at least one brood before use).
Ten vessels per parallel, with one daphnid per vessel, were tested at each concentration and in dilution water to serve as a control. The daphnids were randomly distributed to the test vessels before being arranged in the parallels. Neonates were counted by removing them with a pipette after adult daphnids had been pipetted gently into the replacement test solution.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

At the end of the test, the length of all surviving parent animals were measured to the nearest 0.1 mm using a binocular microscope.

Hardness:

Min 13.3 - Max 15.4

Test temperature:

min. 20.3ºc max 21.5ºC.

pH:

min. 7.3; max. 8.4

Dissolved oxygen:

min. 8.1 mg/o2 max 9.9 mg/02

Salinity:

Not Reported. (Fresh water)

Conductivity:

Conductivity = Min 635 Max 682

Nominal and measured concentrations:

0, 0.6, 1.25, 2.5, 5 and 10 mg/l = Nominal Concentrations were used due to ± 20 % recovery with analysis.

Details on test conditions:

The test duration is fixed at 21 days. Ten vessels per parallel, with one daphnid per vessel, were tested at each concentration and in dilution water to serve as a control. Temperature, pH, dissolved oxygen concentration and total hardnesslconductivity were measured in the control solution and the highest concentration at the beginning and the end of the test as well as at least once a week before and after the solution change. The test was
carried out in a temperature-controlled room. The light regime was 16 h of ambient light per day, provided by fluorescent tubes.

Reference substance (positive control):

not specified

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

1.25 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

2.5 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: Reproduction and Length

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

5 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

other: Weight

Key result

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

2.6 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

Based on these statistical results the lowest NOEC is 1.25 mg/l.

Results with reference substance (positive control):

Not reported however considered standard maintainence practice in GLP laboratories.

Reported statistics and error estimates:

The data was tested for normality using Chi-square test and found to be normally distributed. The data passed Hartley's and Bartlett's tests for
homogeneity of variance ( 0 . 0 5 ) . Analysis of variance was performed on the number of living neonates per parent using the Bonferroni t-test and
verified with a second multiple comparison method, the Dunnett's test.

Quality Criteria

 

Less than 20% mortality occurred in the control group over the test period. The average number of juveniles per parent in the control was greater than 60 per surviving parent daphnid (average = 92.8) after 21 days. Physical chemical parameter all fell within recommended range and no abnormal observations were reported.

 

 

Results of statistical tests

Both length and weight data were found to be normally distributed and displayed homogeneity of variance

Table 1: Number of juveniles per parent alive at end of the test at each test concentration, mean number of neonates per concentration and coefficient of variance (CV).

 

	Concentration (mg/L)
Replicate number	0	0.6	1.25	2.5	5	10
1	81	D	79	49	D	D
2	95	98	63	39	D	D
3	87	91	82	62	D	D
4	111	106	89	60	D	D
5	101	101	77	60	D	D
6	^aD	86	79	D	D	D
7	84	74	79	49	D	D
8	111	86	73	56	2	D
9	81	81	110	38	D	D
10	84	36	90	43	D	D
Mean	92.8	84.3	82.1	50.7	1	0
CV (%)	13.2	24.6	15.1	18.4	141.4	^bNC

^aD = died during the test

^bNC = not calculable

Validity criteria fulfilled:

yes

Remarks:

Yes: <20% mortality in control group over the 21 days, and average number of surviving juveniles was 93 (higher than the minimum acceptable of 60)

Conclusions:

The strong points of this study are that 1) the study was conducted following OECD guidelines, 2) under GLP, and 3) that there was analytical monitoring of the concentration of ammonium thiocyanate during the study. The weak points mainly relate to the lack of provision of information on the results of a test with a reference compound. However, this would not prevent the reproduction of the test.

Based on the results of this study, the 21-d NOEC is 1.25 mg/L and the 21-d EC50 for reproduction is 2.6 mg/L.

Executive summary:

The purpose of this study was to assess the toxicity of ammonium thiocyanate dissolved in fresh water, on the reproductive efficacy ofDaphnia magna STRAUS - clone 5, in a 21-day semi-static test complying with the OECD Guideline No. 211, September 21 1998 and EU guideline C.20 from Annex V of Directive 67/548/EEC. 

 

The test criterion of toxicity used was reproductive capacity expressed as the number of neonates per daphnid per day.

 

The nominal concentrations used in the study were as follows: 0, 0.6, 1.25, 2.5, 5 and 10 mg/I

 

Analytical determinations of the test solutions were made on six occasions during the test. The concentrations were found to remain stable to within±20% of the nominals. The nominal concentrations were used to calculate the effect concentrations.

 

The validity criteria were respected:

Less than 20% mortality occurred in the control group over the test period.

The average number of juveniles per parent in the control was greater than 60 per surviving parent daphnid (average = 92.8) after 21 days.

 

The 21 d EC50s for adult mortality and for reproduction were determined as 3.8 mg/I and 2.6 mg/I, respectively.

 

The No Observed Effect Concentration (NOEC) is determined as the concentration used in the study that is immediately below the Lowest Observed Effect Concentration (LOEC), the latter derived statistically from the data using the appropriate statistical test.

 

Data were found to be normally distributed and homogeneous. Using Dunnett's and Bonferroni-t tests, the Lowest Observed Effect Concentration (LOEC) based on reproductive output, and on parent body length were found to be 2.5 mg/1. The lowest Observed Effect Concentration (LOEC) based on weight of adult daphnids was 5 mg/1.

 

Based on these statistical results, the lowest NOEC is 1.25 mg/L

Description of key information

A study according to OECD TG 211 with Ammonium thiocyanate (CAS-No. 1762-95-4) was taken as read-across source for the Endpoint "Long-term toxicity to aquatic invertebrates"

The effect concentrations determined for Ammonium thiocyanate (CAS-No. 1762-95-4) were adjusted to the molecular weight of Guanidine thiocyanate (CAS-No. 593-84-0).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

1.94 mg/L