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Long-term toxicity to fish

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Reference
Endpoint:
fish early-life stage toxicity
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:
comparable to guideline study
Remarks:
Comparable to guideline study 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 hydrochloride for effects of guanidine dissociated from guanidine nitrate 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.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 210 (Fish, Early-Life Stage Toxicity Test)
GLP compliance:
not specified
Analytical monitoring:
yes
Test organisms (species):
Pimephales promelas
Details on test organisms:
TEST ORGANISM
- Common name: Fathead minnow (Pimephales promelas)
- Source: in-house culture unit


METHOD FOR PREPARATION AND COLLECTION OF FERTILIZED EGGS
- Method of collection of fertilised eggs: removing from the liners by gently rolling them with a fingertip
- Subsequent handling of eggs: pooling and examination under a stereoscope, any unfertilized or damaged eggs were discarded, test started with embryos less than 24hours old


POST-HATCH FEEDING
- feeding of the adult fathead minnowsType/source of feed: frozen brine shrimp (Artemia salina) and Rangens No.3 trout food (Fish and Wildlife Service formulation)
-feeding of the fry: twice daily with new hatched brine shrimp naulii (Colombia, South America), not fedded in the last 24hours of the test to allow their guts to empty prior to weighing
Test type:
flow-through
Water media type:
freshwater
Limit test:
no
Total exposure duration:
35 d
Hardness:
169-197mg/L CaCO3
Test temperature:
24.7-25.8°C
pH:
8.2-8.6
Dissolved oxygen:
5.2-8.5mg/L
Nominal and measured concentrations:
nominal: 400, 200, 100, 50, 25, 0 mg/L
measured: 424, 181, 98.1, 52.7, 27.3, <0.5mg/L
Details on test conditions:
TEST SYSTEM
- Emybro cups (if used, type/material, size, fill volume): egg cups/glass tubing covered at the bottom with 506 micron polyethylene mesh screen/size: 11.5cm length, 50mmID
- Test vessel:
- Material, size, headspace, fill volume: test tanks of 9.4L, covered with 506 micron mesh polyethylene screen, fillvolume: 6.9L of test solution, test tanks arranged in water bath in two rows of six
- Aeration: aerated after day 18 of the test, dissolved oxygen concentration greater than 60% saturation
- Type of flow-through: peristaltic
- Renewal rate of test solution (frequency/flow rate):diluter cylced once an hour, peristaltic pump which delivered GN-stock solution was turned on for 2min every hour between diluter cylces by a Chrontrol programmable timer0.9 tank volumes of test solution per day
- No. of fertilized eggs/embryos per vessel: 45
- No. of vessels per concentration (replicates):2
- No. of vessels per control (replicates): one control per replicate, 2 replicates


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: well water (62m well at Ft. Detrick)
- Alkalinity: 211-226mg/L as CaCO3 (to pH4.5)
- Conductivity:795-875 Micro mhos/cm

OTHER TEST CONDITIONS
- Photoperiod:16hours ligth, 8h dark
- Light intensity:150lux (during test)
- temperature: 25°C (controled by heating and cooling units)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
-time to hatch (= number of days from the start of the test requiered for hatching of at least 50percent of the eggs),
-egg hatching success,
-fry survival,
-overall survival (=contains both embryo survival and fry survival),
-growth(measured at the end of the test including standard length and weight)
- deformities (noted for dead fry and for those that survived to the end of the test)


FERTILIZATION SUCCESS STUDY
- Number of eggs used: 45eggs per egg cup
- Removal of eggs to check the embryonic development on day no.: egg cups removed, examined and dead eggs were removed daily
Reference substance (positive control):
not specified
Key result
Duration:
35 d
Dose descriptor:
NOEC
Effect conc.:
>= 181 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
35 d
Dose descriptor:
LOEC
Effect conc.:
>= 424 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
mortality

Results of the fathead minnow early life stage test with Guanidine Nitrate:

mean measured concentration (mg/L)

time to hatchA(mean days to 50% hatch)

hatching success (%)

fry survival (%)

overall survivial (%)

fry deformities (%)

fry length (mm)

fry weight (mg)

424

4.5

83.3

4.0B

3.3B

2.7

13.7

48

181

4

83.3

93.3

77.8

2.7

14.4

46

98.1

4

87.8

86.1

75.6

1.3

14.7

49

52.7

4

87.8

86.1

75.6

0.0

14.4

47

27.3

4

88.9

80.0

71.1

0.0

14.6

48

<0.5 (control)

4

90.0

88.9

80.0

0.0

14.6

48

ANot analysed statistically

BSignificantly different from the controls (overalla=0.05)

Minor diluter malfunction on day 20 resulted in an average 10% reduction in the test concentrations (within the necessary critical range of 20% appointed in the OECD guideline 210).

Validity criteria fulfilled:
yes
Conclusions:
The 35 – day NOEC values and LOEC-values, based on mortality were 181 and 424 mg/ L Guanidine nitrate respectively.   The sublethal effects included were hatching success, time to hatch, fry and overall survival, measurement of growth (length and weight).   The most sensitive end point was mortality.
Executive summary:

The 35 – day chronic toxicity of Guanidine Nitrate to early life stage of Fathead minnow (Pimephales promelas) was studied under flow through conditions.  Fertilized eggs of Fathead minnow were exposed to control and test chemical nominal concentrations of 400, 200, 100, 50, 25, 0 mg/L, measured concentrations of 424, 181, 98.1, 52.7, 27.3, <0.5mg/L.  The test system was maintained at 25 ºC and a pH of 8.2 to 8.6.  The 35 – day NOEC values and LOEC-values, based on mortality were 181 and 424 mg/ L respectively.   The sublethal effects included were hatching success, time to hatch, fry and overall survival, measurement of growth (length and weight).  The most sensitive end point was mortality.

 

This toxicity study is classified as acceptability and satisfies the guideline requirement for early life toxicity study with fish.

 

Results Synopsis

 Test Organism: Fathead minnow

Test Type Flowthrough

 

LOEC:  424 mg/ L

NOEC:  181 mg/ L

Endpoint(s) Effected:  long-term toxicity to fish

Description of key information

The chronic toxicity of the read-across substance Guanidine Nitrate was tested In a 35-day fish early life stage test (FELS) against Fathead minnow. The duration of the test was 35 days. The NOEC was 181mg/L and the lowest effect concentration was reported at 424mg/L (LOEC).

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater fish:
181 mg/L

Additional information

The NOEC to LOEC of the read-across substance Guanidine Nitrate to Fathead minnow in the 35-day long-term toxicity tested in a fish early life stage test ranged from 181 to 424 mg/L. Mortality was the parameter where significant statistical effect were found. In contrast no statistical relavant effects could be observed for hatching success, fry defromities,or fry growth (length and weight).

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.