3,5-dimethylpyrazole

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:

18 March 2002 to 22 March 2002

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiencies, which do not affect the quality of the relevant results. No analytical determination of concentrations was performed.

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Appropriate amounts of test material were weighted out and dissolve directly into the dilution water. Approximately 2000, 200 and 20 mg of the test material was dissolved in 20 L of dilution water to create the 100, 10 and 1 mg/L stock solutions, respectively. Each solution was sonicated for approximately 3 minutes to aid dissolution.
- Controls: Untreated dilution water was used as the control.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow trout.
- Length at study initiation: 4 to 6 cm.
- Feeding during test Fish were fasted for 24 hours prior to exposure.
- Food type: Standard fish diet.
- Health of fish: All fish were in good health and free from apparent malformations on arrival.

ACCLIMATION
- Acclimation period: For at least 12 days.
- Acclimation conditions: Same as test.
- Type of food: Standard fish diet, same as during the study.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

-

Hardness:

67 mg/L as CaCO3, ranged between 57 and 69 mg/L.

Test temperature:

Ranged from 13.1 to 14.7ºC

pH:

Ranged from 7.08 to 7.87.

Dissolved oxygen:

Ranged from 83.2 to 98.0% air saturation value (ASV).

Nominal and measured concentrations:

Nominal test concentrations: 100, 10, 1.0 mg/L and an untreated control.

Details on test conditions:

TEST SYSTEM
- Test vessel: 25 litre glass tanks, covered with Perspex lids.
- Aeration: Constant throughout the study.
- Renewal rate of test solution (frequency/flow rate): The fish were transferred to freshly prepared test solutions every 24 hours throughout the study.
- No. of organisms per vessel: 7 fish per tank.
- No. of vessels per concentration (replicates): One tank per concentration.
- No. of vessels per control (replicates): One single tank.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The water was prepared in the laboratory by diluting high-grade salts with reverse osmosis water. The water was analysed on 05 November 2001.
- Total dissolved solids (at 180ºC): 92 mg/L
- Pesticides: < 0.01 µg/L, maximum concentration 0.50 µg/L.
- Chlorine: 48 mg/L
- Alkalinity: 10 mg/L
- Calcium: 23 mg/L
- Magnesium: < 3 mg/L
- Conductivity: Ranged from 170.4 to 194.7 µS.
- Intervals of water quality measurement: Parameters were recorded at 0, 24, 48, 72 and 96 hours. Water hardness was determined every 24 hours in the dilution water only.

OTHER TEST CONDITIONS
- Photoperiod: A 16 hour light, 8 hour dark cycle was maintained throughout the test. Light was provided by artificial daylight fluorescent tube lighting.

EFFECT PARAMETERS MEASURED
- Frequency of observations: 1, 4, 24, 48, 72 and 96 hours.
- Observations recorded: Mortality, either physical or behavioural abnormalities.
- Any fish deemed to be in unacceptable distress were removed from the tank and humanely killed, their death was added to the next mortality assessment.

VALIDITY CRITERIA
- Mortality must not exceed 1 out of 7 fish in the control and the dissolved oxygen must remain ≥ 60% of the air saturation value throughout the study.

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)

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

- Mortality in the test groups: One mortality was observed in the 10 mg/L test vessel. The fish was removed at 13:10 hours on the third day of the test, approximately 72 hours after introduction. No other mortalities were observed in any of the test vessels. Cumulative morality data is presented in Table 1.
- Behavioural abnormalities: All surviving fish appeared healthy and normal at all exposure concentration.
- Observations on body length and weight: Body length and weights are presented in Table 2.
- Mortality of control: No mortality was observed.
- Other adverse effects control: None, all fish appeared healthy and normal throughout the study period.
- Any observations effecting the concentration of the test solutions: All test solutions remained clear and colourless throughout the study.
- Water quality measurements are presented in Table 3.

Sublethal observations / clinical signs:

Table 1. Cumulative Mortality Data

Nominal Concentration (mg/L)	0 hrs	24 hrs	48 hrs	72 hrs	96 hrs
100	0/7	0/7	0/7	0/7	0/7
10	0/7	0/7	0/7	1/7	1/7
1.0	0/7	0/7	0/7	0/7	0/7
Control	0/7	0/7	0/7	0/7	0/7

 

Table 2. Surviving Fish Lengths and Weights

Nominal Concentration (mg/L)	Fish No.	Length (mm)	Weight (g)
100	1	48.7	1.51
	2	46.0	1.35
	3	47.6	1.21
	4	49.6	1.51
	5	52.2	1.79
	6	50.4	1.63
	7	49.5	1.54
	Mean	49.1	1.51
	SD	2.0	0.19
10	1	49.9	1.58
	2	45.2	1.01
	3	45.2	1.17
	4	46.8	1.33
	5	47.7	1.32
	6	48.4	1.30
	7	n/a	n/a
	Mean	47.2	1.28
	SD	1.9	0.19
1.0	1	47.6	1.32
	2	49.5	1.39
	3	50.7	1.48
	4	44.4	1.96
	5	50.6	1.57
	6	49.5	1.47
	7	46.8	1.32
	Mean	48.4	1.50
	SD	2.3	0.22
Control	1	47.3	1.61
	2	47.9	1.39
	3	47.9	1.48
	4	46.8	1.42
	5	48.9	1.74
	6	51.0	1.74
	7	48.5	1.36
	Mean	48.3	1.53
	SD	1.4	0.16

 

Table 3. Water Quality Parameters

Parameter	Nominal Concentrations (mg/L)
	100		10		1.0		Control
Water Change	Prior	After	Prior	After	Prior	After	Prior	After
0 hrs
pH	n/a	7.38	n/a	7.40	n/a	7.58	n/a	7.61
Temperature (ºC)	n/a	14.6	n/a	14.5	n/a	14.6	n/a	14.7
Conductivity (µS)	n/a	177.6	n/a	177.6	n/a	177.0	n/a	176.4
Dissolved Oxygen (%)	n/a	92.8	n/a	98.0	n/a	95.9	n/a	97.9
Water Hardness (mg/L) as CaCO3	68
24 hrs
pH	7.77	7.54	7.68	7.64	7.79	7.60	7.82	7.67
Temperature (ºC)	13.1	14.0	13.2	14.1	13.3	14.3	13.5	14.3
Conductivity (µS)	187.7	182.4	187.5	182.8	188.7	183.7	187.3	183.7
Dissolved Oxygen (%)	91.2	83.2	91.6	88.8	89.0	90.2	86.3	86.4
Water Hardness (mg/L) as CaCO3	64
48 hrs
pH	7.33	7.35	7.36	7.42	7.39	7.46	7.08	7.51
Temperature (ºC)	13.4	13.5	13.8	13.5	13.9	13.6	13.9	13.7
Conductivity (µS)	173.2	175.2	170.4	175.4	176.1	175.4	179.7	175.0
Dissolved Oxygen (%)	92.3	93.2	91.3	93.7	91.6	92.1	94.2	94.1
Water Hardness (mg/L) as CaCO3	69
72 hrs
pH	7.71	7.57	7.74	7.68	7.66	7.60	7.87	7.49
Temperature (ºC)	13.5	13.4	13.5	13.3	13.5	13.4	13.6	13.3
Conductivity (µS)	189.2	193.9	188.9	193.1	188.5	192.3	189.0	194.7
Dissolved Oxygen (%)	90.3	84.3	84.6	85.7	88.5	91.2	91.2	88.6
Water Hardness (mg/L) as CaCO3	57
96 hrs
pH	7.36	n/a	7.41	n/a	7.38	n/a	7.29	n/a
Temperature (ºC)	13.4	n/a	13.5	n/a	13.5	n/a	13.6	n/a
Conductivity (µS)	188.8	n/a	189.5	n/a	189.2	n/a	188.9	n/a
Dissolved Oxygen (%)	92.9	n/a	94.1	n/a	93.5	n/a	94.6	n/a
Water Hardness (mg/L) as CaCO3	n/a

Validity criteria fulfilled:

not specified

Conclusions:

The 96 hr LC50 of the test material, under semi-static freshwater conditions, was estimated to be > 100 mg/L, the highest concentration tested. The NOEC was estimated to be 100 mg/L, as there were no mortalities or test item related abnormalities observed after 96 hr exposure.
One mortality was observed in the 10 mg/L exposure group, however this was not dose related and not considered to be as a direct result of exposure to the test material.
The test was considered to be valid as no fish died in the control and dissolved oxygen levels remained above 60% of air saturation value, although no information on maintenance of test substance concentrations at ≥ 80 % of initial concentrations is available as this was not examined.

Executive summary:

The short term toxicity to fish was determined in a 96 hour semi-static freshwater toxicity study performed using Oncorhynchus mykiss. The study was performed in line with GLP and according to the standardised guidelines OECD 203 and EU Method C.1.

The test organisms were exposed to the test material at the following nominal concentrations; 100, 10 and 1.0 mg/L. An untreated control was run concurrently for comparison. The test solution was renewed every 24 hours throughout the study by placing the fish into freshly prepared tanks. Fish were observed for mortality and signs of toxicity at 1, 4, 24, 48, 72 and 96 hours.

Under the conditions of the test the 96 hr LC₅₀ of the test material was estimated to be > 100 mg/L, the highest concentration tested. The NOEC was estimated to be 100 mg/L, as there were no mortalities or test item related abnormalities observed after 96 hr exposure.

One mortality was observed in the 10 mg/L exposure group, however this was not dose related and thus not considered to be as a direct result of exposure to the test material.

The test was considered to be valid as no fish died in the control and dissolved oxygen levels remained above 60% of air saturation value, although no information on maintenance of test substance concentrations at ≥ 80 % of initial concentrations is available as this was not examined.

Description of key information

The toxicity of 3,5-Dimethylpyrazole to freshwater fish has been determined to be LC50 > 100 mg/L and NOEC 100 mg/L in a key study (Hargreaves, Clayton & Carson, 2002) performed according to OECD 203 and EU Method C.1.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

100 mg/L

Additional information

Hargreaves, Clayton & Carson (2002) has been provided as the key study where the acute toxicity of the test material to freshwater fish was determined to be LC₅₀ > 100 mg/L with a NOEC of 100 mg/L. The study was performed to GLP and standardised guidelines and had thus been assigned a reliability score of 1 using the principles for assessing data quality as set out in Klimisch (1997).