Iodomethane

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:

22 January 2001 to 06 April 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

yes

Remarks:

The OECD guideline recommends the use of 5 .0 ± 1.0 cm fish, the test used smaller fish (average 3.3 cm, range: 2.9 to 3.8 cm) to reduce the loading rate in the closed bottle test system. This deviation is not expected to have affected the study results.

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1075 (Freshwater and Saltwater Fish Acute Toxicity Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Japanese MAFF 12 Nousan No 8147

Deviations:

yes

Remarks:

The test was performed at 12 ± 2 °C, rather than 15 ± 2 °C as stated in the JMAFF guidelines but the difference is not expected to affect the study results.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Sampling method: Water samples were collected from each replicate test chamber at test initiation and from each test chamber at 24 hour renewal periods.
- Sample storage conditions before analysis: Samples were placed directly in autosampler vials, capped and analysed as soon as possible without storage.

Vehicle:

no

Details on test solutions:

- A primary stock solution was prepared at a concentration of 100 mg/L by volumetrically adding 88 µL of test material to 2000 mL of dilution water using a gas tight syringe.
- The primary stock was sealed, inverted to mix and covered with aluminium foil. Appropriate aliquots of the primary stock were added to the test chambers that were partially filled with dilution water.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow Trout
- Age at study initiation: Juveniles
- Length at study end: Range 2.9-3.8 cm (Mean 3.3cm)
- Weight at study end: 0.24 g (range 0.14 to 0.36)
- Feeding during test: Fish were fed commercially prepared diet daily during holding period. Fish were not fed during the acclimation (at least 48 hours prior to the test) or test period.
- Holding period:19 days prior to the test in water from the same source and at approximately the same temperature as used during the test.
- Loading was defined as the total wet weight of fish per litre of test water and was 0.44 g fish/L.

ACCLIMATION
- Acclimation period: 51 hours
- Acclimation conditions: Temperature 11.6 to 12.7 °C, pH 8.0 to 8.4 and dissolved oxygen 9.0 to 9.8 mg/L. Animals were not fed during accclimation period.
- During the acclimation period no mortalities occurred and the fish showed no signs of disease or stress.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

140 mg/L as CaCO3

Test temperature:

12 ± 2°C

pH:

7.9 to 8.6

Dissolved oxygen:

≥ 7.4 mg/L (69 % of saturation)

Nominal and measured concentrations:

- Nominal concentrations: 0.80, 1.2, 1.8, 2.7, 4.1 and 6.1 mg/L
- Measured concentrations: 0.62, 0.97, 1.5, 2.3, 3.4 and 5.1 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 3.8 L glass jars with Teflon lined lids
- Type: closed
- Material, size, headspace, fill volume: jars were completely filled with test solution to minimise headspace.
- Jars were covered with aluminium foil to reduce the potential of photodegradation
- Renewal rate of test solution: Test solutions were renewed on a daily basis and the trout were transferred from the old, to new solutions.
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- Biomass loading rate: 0.44 g fish/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The water was obtained from a well on the testing laboratory site, the water is characterised as being moderately-hard. The well water was passed through a sand filter to remove particles greater than approximately 25 µm, and pumped into a 37800 L storage tank where the water was aerated with spray nozzles. Prior to use, the water was filtered (0.45 µm) again to remove microorganisms and particles.
- Specific conductance: 265 µmhos/cm
- Alkalinity: 184 mg/L (as CaCO3)
- Intervals of water quality measurement: at 0, 24 and 48 hours

OTHER TEST CONDITIONS
- Photoperiod: A photoperiod of 16 hours of light and 8 hours of darkness was controlled with an automatic timer. A 30 minute transition period of low light intensity was provided at the beginning and end of the 16-hour light period to avoid sudden changes in lighting.
- Light intensity: at test initiation approximately 289 lux

EFFECT PARAMETERS MEASURED:
- Observations of mortality and other signs of toxicity were made approximately 3, 6, 24, 48, 72 and 96 hours after test initiation. Cumulative percent mortality observed n the treatment groups was used to estimate or calculate the LC50 values and the No-observed effect concentration (NOEC) was determined by visual interpretation of the mortality and biological observation data.

TEST CONCENTRATIONS
- Nominal concentrations selected for use in this study were: 0. 80, 1.2, 1.8, 2. 7, 4.1 and 6.1 mg /L.

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

1.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95 % CL: 1.2 to 1.6 mg/L

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.62 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

> 5.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95 % CL: 3.4 to 5.1 mg/L

Key result

Duration:

72 h

Dose descriptor:

LC50

Effect conc.:

2.1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: 95 % CL: 1.5 to 3.4 mg/L

Details on results:

MEASUREMENT OF TEST CONCENTRATIONS
- Nominal concentrations selected for use in this study were 0. 80, 1.2, 1.8, 2. 7, 4.1 and 6.1 mg /L. Samples collected at test initiation had measured concentrations that ranged from 78 to 88 % of nominal concentrations. "Old" samples collected after 24 hours of exposure had measured concentrations that ranged from 72 to 82 % of nominal. Although a decrease in concentration was observed over the 24-hour time period, the closed bottle system appeared to satisfactorily maintain the test concentrations. Samples collected at the other time intervals had similar recoveries. One Day 2 sample of new test solution (0.80 mg/L nominal concentration) was lost due to instrument malfunction. The sample could not be reanalysed because the test material volatised when the septum of the autosampler vial was perforated.
- When measured concentrations of the samples collected throughout the test were averaged, the mean measured test concentrations for this study were 0.62, 0. 97, 1.5, 2.3, 3.4 and 5.1 mg/L, representing 78, 81, 83, 85, 83 and 84 % of nominal concentrations, respectively. The results of the study were therefore based on mean measured concentrations.

OBSERVATIONS AND MEASUREMENTS
- Water temperatures were within the 12 ± 2 °C range established for the test. Dissolved oxygen concentrations remained ≥ 7.4 mg/L (69 % of saturation) throughout the test. Measurements of pH ranged from 7.9 to 8.6 during the test. Measurements of hardness, alkalinity, acidity, particulate matter, TOC and specific conductance in the dilution water at test initiation were typical of the well water.
- All rainbow trout in the negative control group appeared healthy and normal throughout the test. All rainbow trout in the 0.62 mg/L treatment group also appeared normal throughout the test with no mortalities or overt signs of toxicity observed. After 96-hours of exposure, mortality in the 0.97, 1.5, 2.3, 3.4 and 5.1 mg/L treatment groups was 7.1, 64, 100, 100 and 100 %, respectively. LC50 values at 24, 48, 72 and 96 hours were estimated or calculated from the mortality data and are shown in Table 2.

Reported statistics and error estimates:

When the concentration-response pattern allowed for the calculation of an LC50 value, the data were analysed using a computer program. The program was designed to calculate the LC50 value and the 95 % confidence interval by probit analysis, the moving average method, and binomial probability with nonlinear interpolation. In this study, the binomial method was used to evaluate mortality at 48 and 72 hours. The probit method was used to calculate the 96-hour LC50. The 24-hour LC50 value, the no-mortality concentration and NOEC were determined by visual interpretation of the mortality and biological observation data.

Sublethal observations / clinical signs:

Table 1: Cumulative mortality and observed effects

Mean measured test concentration (mg/L)	Replicate	No. exposed	24 hours		48 hours		72 hours		96 hours		Cumulative percent mortality
			No. dead	Effects	No. dead	Effects	No. dead	Effects	No. dead	Effects
Negative control	A	7	0	7AN	0	7AN	0	7AN	0	7AN	0
	B	7	0	7AN	0	7AN	0	7AN	0	7AN
0.62	A	7	0	7AN	0	7AN	0	7AN	0	7AN	0
	B	7	0	7AN	0	7AN	0	7AN	0	7AN
0.97	A	7	0	7AN	0	7AN	0	1C 6AN	0	6AN 1R	7.1
	B	7	0	7AN	0	7AN	0	7AN	1	6AN
1.5	A	7	0	7AN	0	7AN	0	7C	5	2R	64
	B	7	0	7AN	0	7AN	0	6C 1R	4	3R
2.3	A	7	0	7AN	0	6C 1R	5	2R	7	-	100
	B	7	0	7AN	0	5C 1R	4	3R	7	-
3.4	A	7	0	7AN	0	7R	7	-	7	-	100
	B	7	0	7AN	1	6R	7	-	7	-
5.1	A	7	0	7C	7	-	7	-	7	-	100
	B	7	0	7C	7	-	7	-	7	-

AN= appear normal, C= lethargic and R= lying on bottom

 

Table 2: EC50 values

Time	LC50 (mg/L)	Lower 95 % Confidence limit (mg/L)	Upper 95 % Confidence limit (mg/L)	Statistical method
24 hours	>5.1	-*	-*	Visual inspection
48 hours	4.0	3.4	5.1	Binomial
72 hours	2.1	1.5	3.4	Binomial
96 hours	1.4	1.2	1.6	Probit

-*= Confidence limits could not be calculated with the mortality data obtained

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of this study the 96-hour LC50 value for rainbow trout, Oncorhynchus mykiss, exposed to the test material was 1.4 mg/L. The 95 % confidence limits were 1.2 and 1.6 mg/L. The 96-hour no mortality concentration and the NOEC was 0.62 mg/L .

Executive summary:

The potential of the test material to cause acute toxicity to fish was investigated in accordance with the standardised guidelines OECD 203, EPA OPPTS 850.1075 and Japanese MAFF 8174, under GLP conditions.

Rainbow trout (Oncorhynchus mykiss) were exposed to the test material for 96 hours at the nominal concentrations of 0. 80, 1.2, 1.8, 2. 7, 4.1 and 6.1 mg /L. 2 replicates were performed at each dose level with 7 fish per container. Test material solutions were analysed during the study using HPLC, the mean measured test concentrations for this study were 0.62, 0. 97, 1.5, 2.3, 3.4 and 5.1 mg/L, representing 78, 81, 83, 85, 83 and 84 % of nominal concentrations, respectively. The results of the study were therefore based on mean measured concentrations.

Observations of mortality and other signs of toxicity were made approximately 3, 6, 24, 48, 72 and 96 hours after test initiation.

All rainbow trout in the negative control group appeared healthy and normal throughout the test. All rainbow trout in the 0.62 mg/L treatment group also appeared normal throughout the test with no mortalities or overt signs of toxicity observed. After 96-hours of exposure, mortality in the 0.97, 1.5, 2.3, 3.4 and 5.1 mg/L treatment groups was 7.1, 64, 100, 100 and 100 %, respectively. LC50 values at 24, 48, 72 and 96 hours were estimated or calculated from the mortality data.

Under the conditions of this study the 96-hour LC50 value for rainbow trout, Oncorhynchus mykiss, exposed to the test material was 1.4 mg/L. The 95 % confidence limits were 1.2 and 1.6 mg/L. The 96-hour no mortality concentration and the NOEC was 0.62 mg/L .

Description of key information

Under the conditions of this study the 96-hour LC50 value for rainbow trout, Oncorhynchus mykiss, exposed to the test material was 1.4 mg/L. The 95 % confidence limits were 1.2 and 1.6 mg/L. The 96-hour no mortality concentration and the NOEC was 0.62 mg/L .

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1.4 mg/L

Additional information

Drottar et al. 2002 Trout

The potential of the test material to cause acute toxicity to fish was investigated in accordance with the standardised guidelines OECD 203, EPA OPPTS 850.1075 and Japanese MAFF 8174, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

Rainbow trout (Oncorhynchus mykiss) were exposed to the test material for 96 hours at the nominal concentrations of 0. 80, 1.2, 1.8, 2. 7, 4.1 and 6.1 mg /L. 2 replicates were performed at each dose level with 7 fish per container. Test material solutions were analysed during the study using HPLC, the mean measured test concentrations for this study were 0.62, 0. 97, 1.5, 2.3, 3.4 and 5.1 mg/L, representing 78, 81, 83, 85, 83 and 84 % of nominal concentrations, respectively. The results of the study were therefore based on mean measured concentrations.

Observations of mortality and other signs of toxicity were made approximately 3, 6, 24, 48, 72 and 96 hours after test initiation.

All rainbow trout in the negative control group appeared healthy and normal throughout the test. All rainbow trout in the 0.62 mg/L treatment group also appeared normal throughout the test with no mortalities or overt signs of toxicity observed. After 96-hours of exposure, mortality in the 0.97, 1.5, 2.3, 3.4 and 5.1 mg/L treatment groups was 7.1, 64, 100, 100 and 100 %, respectively. LC50 values at 24, 48, 72 and 96 hours were estimated or calculated from the mortality data.

Under the conditions of this study the 96-hour LC50 value for rainbow trout, Oncorhynchus mykiss, exposed to the test material was 1.4 mg/L. The 95 % confidence limits were 1.2 and 1.6 mg/L. The 96-hour no mortality concentration and the NOEC was 0.62 mg/L .

Sueta, 2003 Carp

The potential of the test material to cause acute toxicity to fish was investigated in accordance with the standardised guidelines OECD 203, EPA OPPTS 850.1075 and Japanese MAFF 8174, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

A 96-hour acute toxicity test of the test material with commoncarp(Cyprinus carpio) was conducted. Seven fish were used in each of five exposure levels [3.00, 2.14, 1.53, 1.09, and 0.781 mg/L (a geometric series with a factor of 1.4)] and a control. The water temperature was maintained within the range of 23 ± 1 °C. The test solutions were renewed once a day in semi-static method.

When analysed using HPLC, the measured concentrations of the test material in the test solutions were 94.0 to 115 % of the nominal concentrations at the preparation and 93.0 to 118 % after 24 hours. The results of the test were estimated based on the nominal concentration because the measured concentration in the test solution was maintained within the range of ± 20 % of the nominal concentration.

Under the conditions of this study the 48-hour LC50 of the test material for common carp was 2.07 mg/L and the 96- hour LC50 was 1.18 mg/L. The lowest test concentration which caused 100 % mortality was 1.53 mg/L and the highest concentration which caused 0 % mortality was 0.781 mg/L at 96 hours. The 96 hour NOEC was 0.781 mg/L.