Estradiol

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Aug to Nov 1996

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 202: "Daphnia sp., Acute immobilisation test and reproduction test". Part I and ll. Adopted 04 Apr. 1984, OECD, Paris, 1993

Principles of method if other than guideline:

Instead of 10 animals per test vessel and 40 animals per concentration (4 replicates) one animal per test vessel and 10 animals per concentration (10 replicates) were used.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

SAMPLING SCHEDULE:
- Samples for the concentration analysis of all old test and control solutions were taken on day 8, 15 and 22 in each test and control vessel and poole- Samples for the concentration analysis were taken on days 1, 8 and 15 from all freshly prepared test solutions and the dilution water

Vehicle:

no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISMS:
- Source: Schering AG, lnstitute for Experimental Toxicology, Berlin (Germany)
- Age: third off-spring of third generation
- Holding: Parent animals kept in glass vessels in water of the same quality and temperature as under experimental conditions
- Daily feeding: laboratory culture of microalgae, e.g. chlorella vulgaris
- Water/Dilution water: Normal tap water, not polluted with harmful concentrations of chlorine, heavy metals or other substances, based on quarterly measurements and in accordance with the German standard "Trinkwasserverordnung"

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

111.73-116.92 mg/L CaCO3

Test temperature:

19.0-21.0 °C

pH:

7.2-8.8

Dissolved oxygen:

7.8-9.0 mg/|.

Salinity:

n.a.

Nominal and measured concentrations:

The test concentrations were dilutions of a saturated solution by 1:160, 1:80, 1:40 1:20 and 1:10

Details on test conditions:

PREPARATION OF THE TEST SOLUTIONS:
- A suspension with a nominal loading of 100 mg/l was stirred for 24 hours and filtered through a glassfibre filter
- Aliquots of the obtained solution were further diluted 1:160, 1:80, 1 :40, 1:20 and 1:10 with tap water in order to prepare the appropriate test concentrations

EXPOSURE CONDITIONS:
- Test vessels: 100 mL test vessel glass filled with 80 ml of the test solutions/dilution water
- Experimental design: 5 test concentration plus 1 control
- Number of test organisms: 10 animals per concentration (10 replicates) were used
- Feeding during the exposure period: daily fed with the microalgae, e.g. Chlorella vulgaris as 0.2 mg carbon per Daphnia
- Photoperiod : 16 h light/8 h dark
- Temperature of incubation unit : mean +/- 1 °C (in the temperature range 18-22 °C), recorded five times a week
- Aeration: none
- Test item concentration : (6.7, 14.0, 30.6, 61.3 and 138.7 µg/L)
- Medium renewal: three times per week
- Criteria of effects: Parent survival, number of off-spring, number of broods and day of first brood was recorded (approx. 3 times/week)
- Hydrographical measurements: Hardness and alkalinity (at start and at the end of the test), pH-value (on day one and weekly), dissolved oxygen concentration (on day one and weekly)

ANALYTICAL MEASUREMENTS (HPLC analysis/UV detection):
- The mean concentrations of the new and old test solutions were used as the basis for the evaluation

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 138.7 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

OBSERVATIONS:
I. Mortality:
- Within the different exposure groups the mean number of off-spring per parent animal varied between 59 and 76 (not strictly exposure-related)
- There is no exposure-dependent pattern in the number of broods However, the highest concentration showed by far the highest number of off-spring
- One Daphnia of the highest test concentration died on day 17 after the third brood
- One Daphnia of the lowest concentration (6.7 µg/L) died on day 13 before breeding due to unknown reasons
- One Daphnia of the 61.3 µ/L concentration died on day 8 before breeding while being transferred into the new solution
- ln two Daphnia of the test concentration 61.3 µg/L no off-spring were observed over the whole exposure time

II. Reproduction (microscopically examination):
- ln one Daphnia there were eggs in the brood pouch which did not hatch
- ln another Daphnia there was no sign of reproduction
- There were no obvious clinical findings explaining the lack of reproduction.

Results with reference substance (positive control):

The culture of Daphnia magna was periodically checked for its sensitivity towards potassium dichromate. The previously obtained EC50 values were between 2.0 and 2.2 mg/L.

Immobilisation of parent animals was not affected by estradiol. Slight not concentration-related decrease in the number of broods per animal following the exposure to estradiol was observed but not considered as substance related. Within the different exposure groups the mean number of off-spring per animal varied between 59 and 76 (not strictly exposure-related).

Validity criteria fulfilled:

yes

Conclusions:

The no observable effect concentration (NOEC) for reproduction after 21 days was greater than or equal 138.7 µg/L.

Executive summary:

The test was performed according to OECD test guideline "Daphnia sp., Acute immobilisation test and reproduction test". Part I and ll. Adopted 04 Apr. 1984, OECD, Paris, 1993". Instead of 10 animals per test vessel and 40 animals per concentration (4 replicates) one animal per test vessel and 10 animals per concentration (10 replicates) were used. The Daphnia were exposed to the test solution and the tap water for a period of 21 days. The test concentrations were dilutions of a saturated solution by 1:160, 1:80, 1:40 1:20 and 1:10 which were selected on the basis of preliminary range-finding tests, where a concentration-related effect in the reproduction was assumed to occur at dilutions higher than or around of 1:10. The test temperature was in the range of 19.0 °C to 21.0 °C. The pH was in a range between 7.2 and 8.8, and the oxygen concentration between 7.8 and 9.0 mg/L. Parent survival, number of off-spring, number of broods and day of first brood was recorded. lmmobilization of parent animals was not affected by the test substance. The no observable effect concentration (NOEC) for reproduction after 21 days was greater than or equal 138.7 µg/L. The slight decrease in the number of broods per animal following the exposure to estradiol is not considered a substance-related effect since it is not concentration-related.

This toxicity study is classified as acceptable and satisfies the guideline requirements for the acute Daphnia study.

Description of key information

The no observable effect concentration (NOEC) for reproduction after 21 days was greater than or equal 138.7 µg/L. 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

138.7 µg/L

Additional information

"Should read: > 138.7 µg/L"

lmmobilization of parent animals was not affected by the substance. The slight decrease in the number of broods per animal following the exposure to estradiol is not considered a substance-related effect since it is not concentration-related.