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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
02 - 11/1984
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Reason / purpose:
reference to other study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Principles of method if other than guideline:
no guideline mentioned but the method was similar as described in the guideline OECD Guideline 211, adopted 3 october 2008
GLP compliance:
not specified
Analytical monitoring:
yes
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Source: in-house culture unit
- Age of parental stock (mean and range, SD): neonates obtained from 11 day-old daphnids for the first daphnid chronic test, 32 day-old daphnids for the second daphnid chronic test
- Feeding during test
- Food type: Ankistrodesmus falcatus raised and supplemented with vitamins as recommended by Goulden et al., 1982
- Amount:2mg/L in the morning, 4mg/L in the afternoon
- Frequency: twice a day


ACCLIMATION
- Acclimation period:test started with less than 24hr old daphnids

Test type:
flow-through
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
1.test: 169mg/L CaCO3
2. test: 165-181mg/L CaCO3
Test temperature:
1. test: 18.3-21.1
2.test: 19.4-20.6
pH:
1.test: 7.8-8.3
2.test:7.8-8.2
Dissolved oxygen:
1.test: 8.1-8.5mg/L
2.test: 7.6-8.7mg/L
Nominal and measured concentrations:
1.test: nominal concentrations: 60/33.6/18.8/10.5/5.9/0mg/L
measured concentration: 52/26.2/16.8/8.8/4.2/<1mg/L
2.test: nominal concentrations: 6.19/3.45/1.97/1.08/0.63/0mg/L
measured concentrations: 6.09/2.9/1.66/1.14/0.75/<1mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type: flow through
- Material, size, headspace, fill volume: 50ml beakers/25ml
- Type of flow-through: peristaltic
- Renewal rate of test solution (frequency/flow rate):two tank volumes of test solution per day
- No. of organisms per vessel:10
- No. of vessels per concentration (replicates):4
- No. of vessels per control (replicates):4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:from 62m well at Ft. Detrick, water softening system, afterwards pumped through a spray nozzle for aeration and sent through a 5micron cellulose acetate cartidge filter, an UV sterilizer, and temperature control equipment prior to use in test
- Conductivity:868micro mhos/cm

OTHER TEST CONDITIONS
- Photoperiod:16hr light, 8hr dark
- Light intensity:400lux(test), 200lux(stock)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
survival, total young per replicate tank, young per female per replicate day, growth reproduction rate, immobilization
Reference substance (positive control):
not specified
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
2.9 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: second test
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
6.09 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: second test
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
4.2 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
reproduction
Remarks on result:
other: first test

Measured GN concentrations – first Daphnid chronic test:

nominal concentration (mg/L)

mean measured concentration (mg/L)

standard deviation

Range

n

60

52

-

-

1

33.6

26.2

±0.87

25-28

4

18.8

16.8

±2.87

15-21

4

10.5

8.8

±0.5

8-9

4

5.9

4.2

±2.06

2-7

4

0

<1A

 

-

4

Abelow detection limit

 

 

Results of first Daphnid chronic test with GN:

Mean measured concentration (mg/L)

ImmobilizationA

(%)

Young per Female per reproductive dayB

total young per tankB

LengthC

(mm)

52.0

100D

-

-

-

26.2

22.5

1.02D

83.8D

2.89D

16.8

5.0

2.91D

331.5D

3.4D

8.8

7.5

4.24D

468.8D

3.78D

4.2

12.5

6.22D

683.5D

4.18D

<1(control)

12.5

7.93

914.0

4.51

ATotal for four replicate tanks at each treatment level

BMean of four replicate tanks at each treatment level

CMean length per daphnid for four replicate tanks at each treatment level

DSignificantly different from the controls (overalla=0.05)

 

Measured GN concentrations – second Daphnid chronic test:

nominal concentration (mg/L)

mean measured concentration (mg/L)

standard deviation

Range

n

6.19

6.09

±0.179

5.94-6.35

4

3.45

2.90

±0.143

2.77-3.05

4

1.97

1.66

±0.140

1.55-1.84

4

1.08

1.14

±0.162

1.04-1.38

4

0.63

0.75A

±0.0520

0.72-0.81

3

0

<1B

-

-

4

Aestimated concentration

BBelow detection limit

 

Results of second Daphnid chronic test with GN:

Mean measured concentration (mg/L)

ImmobilizationA

(%)

Young per Female per reproductive dayB

total young per tankB

LengthC

(mm)

6.09

0

9.32D

1.305

5.01

2.90

0

10.2

1.432

5.12

1.66

0

10.7

1.499

5.17

1.14

5.0

10.5

1.397

5.23

0.75

7.5

10.6

1.400

5.24D

<1(control)

0

10.6

1.453

5.11

ATotal for four replicate tanks at each treatment level

BMean of four replicate tanks at each treatment level

CMean length per daphnid for four replicate tanks at each treatment level

DSignificantly different from the controls (overalla=0.05)

Validity criteria fulfilled:
yes
Conclusions:
The 21-day NOEC based on reproduction was 2.90 mg/L Guanidine nitrate.  Production of offsprings in the treated groups indicated that Guanidine Nitrate had an effect on the reproduction at concentrations greater than 6.09 mg/L. In a first test the toxicity seems to be higher with 4.2mg/L Guanidine Nitrate reported as the lowest concentration where a toxic effect was observed.
Executive summary:

The 21-day-chronic toxicity of Guanidine Nitrate to Daphnia magna was studied under flow through conditions. Daphnids were exposed to control and test chemical at nominal (measured) concentrations of 60, 33.6, 18.8, 10.5, and 5.9mg/L (52, 26.2, 16.8, 8.8, 4.2mg/L) in the first test and 6.19, 3.45, 1.97, 1.08, 0.63 mg/L (6.09, 2.90, 1.66, 1.14, 0.75mg/L) in the second test respectively. In the first test significant toxic effects were found at the lowest concentration tested, 4.2mg/L. Therefore a second test was performed with lower concentrations of Guanidine Nitrate.

 

The 21-day NOEC based on reproduction was 2.90 mg/L.  Production of offsprings in the treated groups indicated that Guanidine Nitrate had an effect on the reproduction at concentrations greater than 6.09 mg/L. In a first test the toxicity seems to be higher with 4.2mg/L Guanidine Nitrate reported as the lowest concentration where a toxic effect was observed.

This study is classified as acceptable and satisfies the guideline requirements for a chronic toxicity study with freshwater invertebrates.

 

Results Synopsis

 

Test Organism Age (e.g. 1stinstar): 24hours

Test Type: Flowthrough

 

21-d-NOEL:  2.90mg/L

21-d-LOEC:  6.09mg/L / 4.2mg/L                    

Endpoint(s) Effected:  long-term toxicity to aquatic invertebrates, also ecotoxicological endpoints:

reproduction, immobilization

 

Description of key information

The long-term toxicity of the read-across substance Guanidine Nitrate to Daphnia magna was tested in a 21-day flow-through test.

The lowest concentration with an effect on reproduction (LOEC) was monitored at a concentration 4.2mg/L in a first chronic test of van der Schalie, 1985 and 6.09mg/L in a second chronic test. The highest concentration of the test item without an effect (NOEC) was found at 2.90mg/L.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
2.9 mg/L

Additional information

The toxic effect of the read-across substance Guanidine Nitrate was monitored in a 21-day toxicity test. 2.9 mg/L of the test substance was the highest concentration where no toxic effect was monitored. Because in a first chronic toxicity test of van der Schalie, 1985 an toxic effect was monitored at the lowest concentration tested (4.2mg/L), a second test was performed with lower concentrations tested. In this second test the lowest effect concentration was reported at 6.09 mg/L. In another study of Cooney et al. (1985) the LOEC was higher. Therefore the van der Schalie study can serve as the key study. It is interesting to mention that Guaninine Nitrate is 10 to 20 times more toxic in a chronic 21-day toxicity test compared to an acute 48h toxicity test which is reported in the same study of van der Schalie, 1985.

Justification for read-across:

Guanidine hydrochloride and guanidine nitrate dissociate in aqueous media to yield the guanidine ion and the respective anion. Therefore it is reasonable to discuss the effects of the ions separately. The chloride ion is a naturally occurring essential ion in human beings with well-known metabolism and mechanisms of action as described in standard textbooks on pharmacology and physiology. As well it is found as salt in the Earth´s crust and is dissolved in seawater. Effects of guanidine hydrochloride are expected to be based primarily on the guanidine ion. The physiological processing of the guanidine ion is expected to be independent of the individual source. Therefore read-across from guanidine nitrate for effects of guanidine dissociated from guanidine hydrochloride is considered valid. This strategy is supported by a quite similar toxicological profile of both substances, as shown in acute toxicity, irritation, sensitization and genotoxic studies.

A more detailed justification for read-across is attached in IUCLID chapter 13.