Bronopol

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:

09 NOEVMBER 2005 to 18 NOVEMBER 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

US EPA OPPTS 850.1075

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Test medium samples were collected from alternating replicate test chambers in each treatment and control group at 0, 48 and 96 hours. The samples were collected from mid-depth in each chamber and processed immediately for analysis.

Vehicle:

yes

Remarks:

DMF 0.1 mL/L in the solvent control and all Bronopol treatment groups

Details on test solutions:

One stock solution was prepared for each of the 5 concentrations tested. A primary stock solution was prepared in DMF at a nominal concentration of 600 mg/mL. Aliquots of the primary stock solution were proportionally diluted with DMF to prepare the additional stock solutions at concentrations of 330, 180, 100 and 55 mg/mL. The five stock solutions were mixed by inversion and appeared clear and yellow.
The stock solutions were injected (12.5 μL/min) into the diluter mixing chamber where they were mixed with well water at a rate of 125 mL/min to achieve the desired test concentrations. The test solutions appeared clear and colorless in the test chambers during the test.

Test organisms (species):

Lepomis macrochirus

Details on test organisms:

Species/strain: Bluegill (Lepomis macrochirus)
Source: Northeastern Aquatics, Rhinebeck, New York, USA
Wild caught: No
Age/size: Age not specified in the report;
Average length at test start: 3.0 cm (range: 2.8-3.1 cm, n=10);
Average wet weight at test start: 0.34 g (range: 0.24-0.41 g, n=10)
Diet: Commercially-prepared diet (Zeigler Brothers, Inc., Gardners, Pennsylvania)
Amount of food: Not specified in the report
Feeding frequency: Daily until 2 days prior to the start of the test.
Pretreatment: 2-weeks acclimation period to the test water and temperature;
there were no mortalities and fish showed no signs of desease or
stress.
Feeding of animals during test: No

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

136 mg/L as CaCO3

Test temperature:

21.5 – 22.0°C

pH:

8.0 – 8.3

Dissolved oxygen:

7.9 – 8.6 mg/L (≥91% of saturation at 22°C)

Salinity:

no data available

Conductivity:

310 μmhos/cm

Nominal and measured concentrations:

blank control, solvent control, 5.5, 10, 18, 33 and 60 mg/L
Besides Bronopol, a secondary component (resulting from either alkaline rearrangement or degradation) was found in the test medium of all treatment groups. Amounts of Bronopol analysed at 0 and 96 hours were between 34 and 48% and 23 and 55% of nominal, respectively, whilst the sum of Bronopol and the secondary component amounted to 98 to 103% of nominal at any sampling.

see Table 1 in "any other information on materials and methods incl. tables"

Details on test conditions:

TEST SYSTEM
- Test vessel: 25-L Teflon-lined stainless steel aquaria filled with approximately 15 L of test water (equivalent to a depth of 18 cm)

- Aeration: The well water in the storage tank was aerated.
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate): Approximately 6 volume additions every 24 hours
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): 2
- Biomass loading rate: 1.5 L/fish; instantaneous loading: 0.22 g fish/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Freshwater from a well approximately 40 m deep located on the test site. The well water was passed through a sand filter to remove particles >25 μm, and pumped in a 37800-L storage tank where the water was aerated. Prior to use, the water was filtered to 0.45 μm.

- Alkalinity: 180 mg/L as CaCO3
- Ca/mg ratio:
- Culture medium different from test medium:
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h of fluorescent light and 8 h of darkness with 0.5h transition period.
- Light intensity: 163 lux at the start of the test

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations:
- Results used to determine the conditions for the definitive study:

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

11 mg/L

95% CI:

9.3 - 13

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Remarks:

LC 50 based solely on mean measured bronopol concentration

Basis for effect:

mortality (fish)

Details on results:

please see section "Any other information on results incl. tables"

Reported statistics and error estimates:

LC50 values and the 95% confidence limits were calculated using Probit analysis. LC0 and LC100 were taken directly from the toxicity data.

Sublethal observations / clinical signs:

Table 2: Mortality data

Bronopol concentration (nominal / mean measured^&) [mg/L]	Mortality (replicate A/B)
	Number     24 h          48 h          72 h          96 h				Percentage     24 h         48 h          72 h           96 h
Control	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)
Vehicle control	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)
5.5 / 1.5	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)
10 / 2.9	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)	0  (0/0)
18 / 7.0	1  (1/0)	1  (1/0)	1  (1/0)	1  (1/0)	5  (10/0)	5  (10/0)	5  (10/0)	5  (10/0)
33 / 15	12  (7/5)	15  (8/7)	17 (10/7)	17 (10/7)	60 (70/50)	75 (80/70)	85 (100/70)	85 (100/70)
60 / 31	20 (10/10)	--	--	--	100 (100/100)	--	--	--

^& arithmetic mean of the measured concentrations of parent Bronopol in the test medium samples collected at 0, 48 and 96 hours

 

Table 3: Effect data based on mean measured bronopol concentrations

	24 h [mg/L]	95 % c.l.	48 h [mg/L]	95 % c.l.	72 h [mg/L]	95 % c.l.	96 h [mg/L]	95 % c.l.
LC0	2.9	n.a.	2.9	n.a.	2.9	n.a.	2.9	n.a.
LC50	13	11 – 16	12	10 – 14	11	9.3 – 13	11	9.3 - 13
LC100	31	n.a.	31	n.a.	31	n.a.	31	n.a.

n.a. not applicable

 

Validity criteria fulfilled:

yes

Conclusions:

The test item showed acute toxicity to bluegill with a LC 50 of 11.0 mg/L

Description of key information

Acutely harmful to aquatic organisms.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

11 mg/L

Additional information

The acute toxicity of Bronopol to bluegill sunfish (Lepomis macrochirus) was tested in a flow-through test system according to OECD TG 203 [Wildlife International, Ltd., Easton, MD, USA], 2006. The LC50 was 11.0 mg/L based on mean measured concentrations in a flow-through system. Several other supporting data are also available:

US EPA Guideline OPP 72 -1 [The Boots Company 1984 (a)]. After 96 hours, the LC50 was determined to be 35.7 mg/L (measured), whereas symptoms of toxicity occurred at a concentration of 20 mg/L (measured).

Two more supporting studies conducted under equal testing conditions as the key study show similar results [The Boots Company (b) and (c)]. The LC50 for Salmo gairdneri was determined to be 41.2 mg/L (measured) after 96 h and the LC50 for the seawater species Cyprinodon variegatus was determined to be 57.6 mg/L (measured) after 96 h, respectively.