Desmedipham

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

1989-09-13 to 1990-03-13

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 202

Version / remarks:

April 1984

Deviations:

yes

Remarks:

Individual exposure during reproduction phase

GLP compliance:

yes

Specific details on test material used for the study:

The test material is in a solid form.

Analytical monitoring:

yes

Details on sampling:

Duplicate samples from concentrations 0.0032, 0.032, 0.32 mg/L and the blanks were taken at the beginning and end of the first renewal and at the beginning and end of a last renewal period. Samples of 3.2 mg/L were only taken at the first renewal period. Samples were analysed by HPLC with UV detection.

Vehicle:

yes

Remarks:

Acetone

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Controls: Test medium without test substance or other additives, and test medium without test substance but with 0.1 mL/L acetone.
- Other relevant information: For formulation of the test concentrations used in the main study: the test substance was not very well soluble in water; therefore, the additive acetone was used. For every concentration a separate stock solution was prepared. During the pre-reproduction period, 2 L test medium per concentration was divided over 4 vessels with a final volume of 500 mL per vessel. During the reproduction period, 1 L test medium per concentration was divided over 10 vessels with a final volume of 50 mL per vessel. Directly after treatment of the test media, the daphnia were introduced into the test medium.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Age at study initiation: less than 3 days old
- Feeding during test: Yes
- Food type: A suspension of fresh water algae.
- Frequency: Once a day.

Test type:

semi-static

Water media type:

other: Dutch standard water (DSW)

Limit test:

no

Total exposure duration:

21 d

Hardness:

84.8 mg CaCO3/L

Test temperature:

20 ± 1°C.

pH:

7.5 - 8.9

Dissolved oxygen:

7.2 - 10.5 mg/L

Nominal and measured concentrations:

Nominal concentrations of 0.0032, 0.01, 0.032, 0.1, 0.32, 1.0 and 3.2 mg/L, alongside a blank control and a solvent control.

Details on test conditions:

- 40 daphnids, in 4 replicates of 10, were exposed to nominal concentrations of 0.0032, 0.01, 0.032, 0.1, 0.32, 1.0 and 3.2 mg/L in a semi-static system for 21 days. Blank control and a solvent control (acetone 0.1 mL/L) were handled similarly. After 7 days of exposure, 10 females were selected and were exposed individually for the rest of the test. Observations were made at least three times a week.
- Dutch standard water was used with pH ranging from 7.5 - 8.9 and dissolved oxygen from 7.2 - 10.5 mg/L and hardness 84.8 mg CaCO3/L, was used as test medium. Test medium was renewed three times a week. Test temperature was 20 ± 1°C.
- Chemical analysis (desmedipham and EHPC): duplicate samples from concentrations 0.0032, 0.032, 0.32 mg/L and the blanks were taken at the beginning and end of the first renewal (0-48 h) and at the beginning and end of one of the last renewals (0-72 h). Samples of 3.2 mg/L were only taken at the first renewal period. Samples were analysed by HPLC with UV detection.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours photoperiod daily
- Light intensity: 1000 lux

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

10 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: immobility including mortality, and reproduction.

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

32 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: immobility including mortality, and reproduction.

Details on results:

Analytical results
The summarized percentage (Desmedipham technical + EHPC) mean recovery range at t=0 was between 62 and 83%. Neither desmedipham nor its hydrolysis product EHPC was detected in samples taken after 48 and 72 hours. The results are however based on nominal concentration of desmedipham.

Biological results
100% mortality was observed in concentration of 3.2 mg/L in the beginning of the test (day 2) and hence, the results are not included to the Table B.9.2.5.1-3. All groups exposed up to and including 0.32 mg/L produced young daphnids by the day 9. The parental 48 hour EC50 value for immobilisation was 0.59 mg/L with 95% confidence intervals of 0.50 - 0.70 mg/L. The 21-day EC50 value was above the highest tested concentration of 0.32 mg/L. The NOEC value for the reproduction was 0.01 mg/L and the LOEC value was 0.032 mg/L.

See "Attachments" in "Overall remarks, attachments" for the table.

Validity criteria fulfilled:

yes

Remarks:

The mortality parents (female daphnia) at end of test was = 20%, and the mean number living offspring/parent at end of test was = 60.

Conclusions:

Under the conditions used in the present study, desmedipham technical appears to induce no inhibition on the reproduction of Daphnia magna at nominal concentrations of 0.01 mg/L and lower in a 21-day reproduction test. The overall No Observed Effect Concentration (NOEC) appeared to be nominally 0.01 mg/L and the overall Lowest Observed Effect Concentration (LOEC) appeared to be nominally 0.032 mg/L.

Executive summary:

The cladoceran, Daphnia magna, was exposed to desmedipham tehnical at nominal concentrations of 0.0032, 0.01, 0.032, 0.1, 0.32, 1.0 and 3.2 mg/L under semi-static conditions for 21 days. There was no inhibition on the reproduction of Daphnia magna at nominal concentrations of 0.01 mg/L and lower in a 21-day reproduction test. A NOEC and LOEC value of 0.01 mg a.s./L and 0.032 mg a.s./L, respectively (for immobilisation including mortality, and reproduction) was obtained based on nominal concentrations.

Reference 2

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-01-03 to 2012-09-26

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

October 3, 2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1300 (Daphnid Chronic Toxicity Test)

Version / remarks:

1996

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: ASTM Standard E1193-97: Standard Guide for Conducting Daphnia magna Life-Cycle Toxicity Tests.

Version / remarks:

2004

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

The test material is in a solid form.

Analytical monitoring:

yes

Details on sampling:

Samples were collected from each treatment and control group five days prior to the start of the test after conditioning the diluter for two days. Water samples also were collected from alternating replicate test chambers in each treatment and control group at the beginning of the test, at approximately weekly intervals during the test and at the end of the test to measure concentrations of the test substance. All samples were collected from mid-depth, placed in glass vials, acidified with two drops of 10% phosphoric acid and processed immediately for analysis.

Vehicle:

yes

Remarks:

dimethylformamide (DMF)

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Differential loading: The five test substance stock solutions were injected into the diluter mixing chambers at a rate of 7.80 µL/minute where they were mixed with dilution water delivered at a rate of 155 mL/minute to achieve the desired test concentrations.
- Controls: Negative control (dilution water only) and positive control (acidified HPLC-grade DMF)
- Other relevant information: All test solutions were adjusted to 100% active substance during preparation, based on the test substance purity (99.5%). Prior to stock solution preparation, HPLC-grade dimethylformamide (DMF) was acidified using 10% phosphoric acid to stabilize the test substance. The negative control received dilution water only. The solvent control was prepared by delivering acidified HPLC-grade DMF to the mixing chamber for the solvent control. The concentration of DMF in the solvent control and all desmedipham treatment groups was 0.05 mL/L.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Justification for species other than prescribed by test guideline: The cladoceran, Daphnia magna, was selected as the test species for this study. This species is representative of an important group of aquatic invertebrates and were selected for use in the test based upon past history of use in the laboratory.
- Age at study initiation (mean and range, SD): Daphnid neonates used in the test were less than 24 hours old.

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES, INCLUDING CULTURING CONDITIONS
The 5 adult daphnids used to supply neonates for the test were held for 21 days prior to collection of the juveniles for testing, and had each produced at least one previous brood. Adult daphnids in the culture had produced an average of at least three young per adult per day over the 7-day period prior to the test. The adults showed no signs of disease or stress and no ephippia were produced during the holding period. To initiate the test, the juvenile daphnids were collected from the cultures and indiscriminately transferred one or two at a time to transfer chambers until each chamber contained 5 daphnids. Each group of neonates then was impartially assigned to a control or treatment group and the neonates were transferred to the test compartments to initiate the test. All transfers were made below the water surface using wide-bore pipettes.

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Remarks on exposure duration:

Observations of each first-generation daphnid were made daily during the test. With the onset of reproduction, neonates produced by the first-generation daphnids were counted and then discarded every Monday, Wednesday and Friday during the test.

Hardness:

140 (mg/L as CaCO3)

Test temperature:

20 ± 1°C

pH:

7.9 - 8.2

Dissolved oxygen:

=61% of saturation (5.5 mg/L).

Salinity:

180 (mg/L as CaCO3)

Conductivity:

319 (µS/cm)

Nominal and measured concentrations:

Nominal test concentrations: 6.3, 13, 25, 50 and 100 µg a.s./L, alongside a dilution water control and a solvent control.
Mean measured concentrations : 4.1, 6.3, 10, 20 and 38 µg a.s./L

Details on test conditions:

TEST SYSTEM
Two replicate test chambers were tested for each treatment and control group. Each replicate contained two compartments with five daphnids, resulting in a total of 20 daphnids in each treatment and control group.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours of light and 8 hours of darkness
- Light intensity: 318 lux

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

20 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: growth (based on length), survival and reproduction

Details on results:

Measurement of Test Concentrations
Results of analyses to measure concentrations of desmedipham and EHPC in the pretest diluter verification samples are presented in Table 2.

Water Chemistry Measurements
Measurements of temperature, dissolved oxygen and pH in the test chambers are summarized in Table 4.

Survival and Clinical Observations
A summary of survival among the first-generation daphnids is presented in Table 5.

See "Attachments" in "Overall remarks, attachments" for the tables.

Validity criteria fulfilled:

yes

Conclusions:

The study fulfils the validity criteria set in OECD TG 211 for control mortality and for the mean number of living offspring per parent animal. Based on the combined recoveries of desmedipham and EHPC, daphnids exposed at the concentration of 95 µg a.s./L (38 µg a.s./L for desmedipham recovery only) had statistically significant reductions in length, survival and reproduction in comparison to the pooled control. Consequently, the NOEC, based on these endpoints, was 49 µg a.s./L (20 µg a.s./L for desmedipham recovery only). The LOEC was 95 µg a.s./L (38 µg a.s./L for desmedipham recovery only) and the MATC was calculated to be 68 µg a.s./L (28 µg a.s./L for desmedipham recovery only). The 21-day EC50 value for adult survival was >95 µg a.s./L (>38 µg a.s./L for desmedipham recovery only), the highest concentration tested. The 21-day EC50 value for reproduction was 75 µg a.s./L (30 µg a.s./L for desmedipham recovery only).

Executive summary:

The cladoceran, Daphnia magna, was exposed to desmedipham at mean measured concentrations of 4.1 to 38 µg a.s./L under flow-through conditions for 21 days. There were no statistically significant treatment-related effects on survival, reproduction or growth, measured as length, at concentrations 20 µg a.s./L. There were also no statistically significant treatment-related effects in any of the treatment groups on growth, measured as dry weight. Growth, measured as length, survival and reproduction were the most sensitive biological endpoints measured in this study. A NOEC value of 20 µg a.s./L based on arithmetic mean measured concentration of desmedipham was determined.

Description of key information

A study was conducted to investigate the chronic toxicity of Desmedipham to Daphnia magna over 21 days. The 21-d NOEC was determined to be 0.020 mg/L (based on mean measured concentrations).

Even though the study by Coenen (1990) resulted in a lower endpoint (NOEC = 0.01 mg/L) compared to the endpoint (NOEC = 0.020 mg/L) from the study be Claude et al. (2012) the later endpoint was identified as the key endpoint/study. The study by Claude et al. 2012 performed under flow-through conditions and in accordance with OECD 211. The study by Coenen 1990 was performed under semi-static conditions according to OECD 202, which is however the guideline for acute toxicity to Daphnia magna and shows deviations from the current reproductive toxicity to Daphnia magna guideline OECD 211. Based on the more realistic test design and performance according to the current OECD guideline for reproductive toxicity the study by Claude et al. (2012) is the key study. 

In the table below all available studies are listed. For some studies only the results are presented since they are not considered relevant due to the reasons given under “Assessment”. All available studies have been evaluated within the scope of Plant Protection Regulation in the respective Draft Renewal Assessment Report (DAR) under Regulation (EC) 1107/2009.

Test species	Result	Assessment	Reference
Daphnia magna	21-d NOEC = 0.020 mg a.s./L (mean measured)	Key study	Claude et al. (2012)
Daphnia magna	21-d NOEC = 0.01 mg a.s./L (nominal) LOEC = 0.032 mg a.s./L (nominal)	Supporting study	Coenen (1990)
Daphnia magna	21-d NOEC = 0.18 mg a.s./L (nominal)	The study does not meet all validity criteria. (Number of living offspring per parental animal in the control is not met.)	Handley et al. (1992)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

0.02 mg/L