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Short-term toxicity to fish

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Reference
Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Remarks:
Public Literature
Adequacy of study:
key study
Study period:
1994
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
equivalent or similar to
Guideline:
other: ASTM E279-80 (1980)
Principles of method if other than guideline:
This report refers to other studies that have been carried out such as Benoit et al (1982), Sprague (1969), Trimmed Spearman-Karber method (Hamiliton et al, 1977). The test described generally follows OECD 203.
GLP compliance:
no
Analytical monitoring:
yes
Details on sampling:
Water samples for chemical analyses were taken four times during the 96-hour acute tests and twice weekly during embryo-larval and 28-day larval tests. These water samples were taken alternately from each complete set of replicate tanks (6 tanks). The analyses of each et of 6 water samples included a replicated sample analysis for determination of percentage dupicate agreement, a spiked control sample and a series of analytical standards.
Vehicle:
no
Details on test solutions:
Stock solutions were prepared by dissolving the chemical in Lake Superior water using a high-speed stirrer. Stock solutions were prepared were prepared daily to wekly depending on chemical stability. Stock solutions were transferred to a glass stock bottle inside the vented diluter snclosure using Teflon tubing and air pressure. During each test, a predetermined volume (mL/min) of stock solution was continuously pumped from the stock bottle into the mixing cell of the diluter system.
Test organisms (species):
Oryzias latipes
Details on test organisms:
The medaka used for all tests were obtained from the Environmental Research Laboratory-Duluth (ERL-D) culture unit. Juvenile medeka for acute tests were reared in tanks at 25 °C and fed live Biomaine brand brine shrimp. Fish were not fed for 24-h before or during acute testing. Twenty medaka were exposed per concentration, ten per replicate, in acute tests. Medaka used for acute tests ranged from 28 - 43 days old and weighed 18 - 71 mg. Mean weights of test fish were determined by weighing the control group (20 fish) at the end of the 96-hour exposures.
Test type:
flow-through
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Hardness:
The mean and range for total hardness was 45.8 (38.0 - 52.0) mg/L as CaCO3 for all tests. The mean and range of alkalinity was 45.9 (35.0 - 58.5) mg/L as CaCO3 for all tests.
Test temperature:
25 ± 1 °C
pH:
The arithmetic mean, standard deviation and range of pH readings for all tests was 7.88 ± 0.18 (7.31 - 8.85) N = 333
Dissolved oxygen:
Measurements obtained from all studies - 6.8 ± 0.7 (5.0 - 8.5) N = 339.
Salinity:
Not applicable
Nominal and measured concentrations:
Measured water concentrations:
96-hour acute test: < 0.25, 1.48 ± 0.39, 2.45 ± 0.31, 4.43 ± 0.61, 8.81 ± 0.41, 19.8 ± 1.7
28-day larval test: < 0.25, 0.27 ± 0.07, 0.47 ± 0.16, 0.92 ± 0.33, 1.92 ± 0.45, 4.85 ± 0.82
Details on test conditions:
Continuous-flow mini-diluter exposure systems with vented enclosures were used for all tests. The diluters generated five exposure concentrations and a control, all in replicate, with a dilution factor of 0.5. Exposure tanks were glass aquaria 18.5 x 14.0 x 13.0 cm deep. Each exposure tank had a 8.6 cm standpipe which resulted in a tank volume of 2.0 L. Flow rates and 90 % replacement times were (Sprague 1969) were 25 mL/min and 2.8 hours respectively, during all tests. Fluorescent lamps provided a light intensity that ranged from 12 to 25 lumens at the water surface. A 16-hour photoperiod was used for all tests.

Twenty medaka were exposed per concentration, ten per replicate, in acute tests. Medaka used for acute tests ranged from 28 - 43 days old and weighed 18 - 71 mg. Mean weights of test fish were determined by weighing the control group (20 fish) at the end of the 96-hour exposures. All 28-day larval tests were initiated by randomly distributing groups of 60 larvae. (0 - 3 days old) to each of the 12 exposure tanks. The test was started by placing groups of fish in tanks containing dilution water only and then starting the toxicant dosing pump so that appropriate test concentrations were achieved gradually within approximately 3 hours. Fish were fed live brine shrimp twice per day, Monday through Friday. Observations for determining larval survival were made daily. Dead organisms were removed during the daily tank cleaning procedure. After 24-hours, remaining fish in each tank were weighed and transferred to the clean water for the 5-month induction time carcinogenicity portion of the study.
Reference substance (positive control):
not specified
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% confidence limits - 3.48 - 4.60
Duration:
28 d
Dose descriptor:
other: chronic value
Effect conc.:
1.33 mg/L
Details on results:
Survival and growth of medaka were significantly reduced by benzyl acetate concentrations of 1.92 mg/L and above (Table 1). Based on these effects, the estimated MATC for benzyl acetate lies between 0.92 and 1.92 mg/L. The chronic value and 96-h LC50 for benzyl acetate for medaka were 1.33 mg/L and 4.00 mg/L respectively. The resulting acute-to-chronic ratio was 3.0.
Results with reference substance (positive control):
No data
Reported statistics and error estimates:
The Trimmed Spearman-Karber method (Hamiliton et al, 1977) was used to estimate 96-hour LC50 values and 95 % confidence limits for the acute test. Mortality data from the replicate tanks were combined before the LC50 determinations were conducted. Percent hatch and percent survival data were normalised by using one-way analysis of variance with an F-test of significance (p = 0.05) and to subsequent analysis with Dunnett's one-sided comparison (p=0.05) of treatment means to control means. The mean chronic value was determined by calculating the geometric mean of the estimated MATC concentrations. The 96-h LC50 values were divided by the mean chronic value to determine an acute-to-chronic ratio.

Table 1        Benzyl Acetate Data

 

Control

Tank No. 2

Tank No. 3

Tank No. 4

Tank No. 5

Tank No. 6

96-Hour Acute Test

 

Measured Water Concentrations

< 0.25a

1.48 ± 0.39b

2.45 ± 0.31

4.43 ± 0.61

8.81 ± 0.41

19.8 ± 1.7

% Survivalc

100

100

100

80

0

0

28-Day Larval Test

Measured Water Concentrations

< 0.25a

0.27 ± 0.07b

0.47 ± 0.16

0.92 ± 0.33

1.92 ± 0.45

4.85 ± 0.82

% Survival d

98.3

95.8

99.2

98.3

19.2

6.6

28-Day Weights (mg)

30.6 ± 10.1

30.3 ± 10.5

31.2 ± 10.7

31.9 ± 12.0

7.65 ± 4.71e

1.88 ± 0.64e

a Detection limit of the analytical measurement procedure

b Mean ± standard deviation

c Based on 20 organisms exposed per concentration

d Based on 120 organisms exposed per concentration

e Significantly different than controls (p=0.05)

Validity criteria fulfilled:
yes
Conclusions:
The acute and chronic studies with benzyl acetate were carried out under flow-through test conditions, test species was medaka (Oryzias latipes).The 96 hour LC50 was calculated to be 4 mg/L (with 95% confidence limits of 3.48 – 4.60mg/L). The chronic value was calculated to be 1.33 mg/L.
Executive summary:

This summary summarises a published paper where the toxicity of a number of materials were assess for acute (96 hours) and chronic (28 days) effects. Only the results of the studies with benzyl acetate are reported in this summary.

No test guidelines were specified but the tests appear to have been conducted according to ASTM guideline E279-80 (1980). The 96 hour acute study design is similar to that described in the OECD 203 guideline. 

The acute and chronic studies were carried out under flow-through test conditions, test species was medaka (Oryzias latipes). Mean measured exposure concentrations in the acute toxicity study were 1.48, 2.45, 4.43, 8.81 and 19.8 mg/L, corresponding mortality was 0, 0, 20, 100 and 100%.   In the chronic study measured concentrations were 0.27, 0.47, 0.9, 1.92 and 4.85 mg/L, corresponding 28 day weights were 30.6 mg in the control and 30.3, 31.2, 31.9, 7.65 and 1.88 mg in the test treatments.

The 96 hour LC50 was calculated to be 4 mg/L (with 95% confidence limits of 3.48 – 4.60mg/L).

The chronic value was calculated to be 1.33 mg/L.

Description of key information

This summary summarises a published paper (Holcombe et al, 1995) where the toxicity of a number of materials were assess for acute (96 hours) and chronic (28 days) effects.  Only the results of the studies with benzyl acetate are reported in this summary.
No test guidelines were specified but the tests appear to have been conducted according to ASTM guideline E279-80 (1980). The 96 hour acute study design is similar to that described in the OECD 203 guideline.
The acute study was carried out under flow-through test conditions, test species was medaka (Oryzias latipes). Mean measured exposure concentrations in the study were 1.48, 2.45, 4.43, 8.81 and 19.8 mg/L, corresponding mortality was 0, 0, 20, 100 and 100%. The 96 hour LC50 was calculated to be 4 mg/L (with 95% confidence limits of 3.48 – 4.60mg/L).

Key value for chemical safety assessment

LC50 for freshwater fish:
4 mg/L

Additional information

The benzyl acetate acute and chronic studies were carried out under flow-through test conditions, test species was medaka (Oryzias latipes). The 96 hour LC50 was calculated to be 4 mg/L (with 95% confidence limits of 3.48 – 4.60 mg/L).