Desmedipham

Sediment toxicity

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2004-07-27 to 2005-02-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 219 (Sediment-Water Chironomid Toxicity Test Using Spiked Water)

Version / remarks:

2001

Deviations:

not specified

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:

Concentrations of Desmedipham and Ethyl-3-hydroxyphenyl carbamate in the samples were determined using a PE SCIEX API 3000 LC/MS/MS coupled with an Agilent Series 1100 HPLC system operated in the multiple reaction monitoring (MRM) mode. The mass spectrometer was equipped with a PE SCIEX Heated Nebulizer ion source. Chromatographic separations were achieved using a Phenomenex Luna C-18 (150 x 3.00 mm I.D., 5-µm particle size) analytical column.

Concentrations of Desmedipham and Ethyl-3-hydroxyphenyl carbamate were also determined by HPLC/UV using an Agilent Series 1100 High Performance Liquid Chromatograph (HPLC) equipped with an Agilent Series 1100 Variable Wavelength Detector. Chromatographic separations were achieved using a YMC Pack ODS-AM column (150 mm x 4.6 mm I.D., 3-µm particle size).

Vehicle:

yes

Remarks:

Acetone (0.1 mL)

Details on sediment and application:

Test Sediment
Formulated sediment based on the recommendations of proposed OECD Guideline 218 and 219 (1 and 3) was used as the test sediment. The sediment was initially composed of approximately 5.0% sphagnum peat moss, 20% kaolin clay, and 75% industrial quartz sand (Appendix 2). Additional peat moss was added to bring the organic carbon content into an acceptable range. The adjusted sediment was composed of approximately 12.5% sphagnum peat moss, 18% kaolin clay, and 69% industrial quartz sand (Appendix 2). The dry constituents of the soil were mixed in a PK Twinshell mixer for approximately 20 minutes. The dry soil was stored under ambient conditions until used. The soil was characterized as having a percent organic matter content of 4.2, a percent organic carbon content of 2.4, a moisture content of 16.8%, pH of 7.7, cation exchange capacity of 7.4 (meq/100g) and a particle size distribution of 75% sand, 10% silt, and 15% clay.

Dilution Water
The water used for culturing and testing was freshwater obtained from a well approximately 40 meters deep located on the Wildlife International, Ltd. site. The well water is characterized as moderately-hard water. The specific conductance, hardness, alkalinity and pH measurements of the well water during the four-week period immediately preceding the test are presented in Appendix 3. The well water was passed through a sand filter and pumped into a 37,800-L storage tank where the water was aerated with spray nozzles. Prior to use, the water again was filtered to 0.45 µm to remove fine particles.

Test Apparatus
Four replicate test chambers (1-quart glass jars) were prepared for each treatment and control group for evaluation of survival and emergence. Five additional test chambers were prepared for each treatment and control group for the measurement of pH in the sediment, and five additional replicates were prepared for the control groups, the low, middle and high treatment groups for analytical purposes. For each replicate, the test chamber was marked to a depth of approximately 2 cm. Clean formulated sediment was added to the test chambers until reaching the 2 cm mark and overlying water (600 mL) was slowly added to each test chamber.
The depth of water and sediment in a representative test chamber were approximately 8.0 and 2.0 cm, respectively. The water was replenished in the test chambers with reverse-osmosis water on days 10 and 22 to maintain the 1:4 soil: overlying water ratio. Gentle aeration (greater than 1 bubble per second, but not so great as to disturb the sediment) was applied to each chamber using glass pipettes positioned not closer than 2 cm from the sediment surface. Test chambers were covered with loose plastic covers to minimize evaporation, and were labeled with the project number, test concentration and replicate. The test chambers were randomly positioned in an environmental chamber designed to maintain a temperature of 20 ± 2°C and the sediment/water mixtures were allowed to settle for twenty-five hours prior to the introduction of test organisms. Aeration was removed from the test chambers at the time the organisms were added and commenced again when the test substance was added (24 hours later).

Test organisms (species):

Chironomus riparius

Details on test organisms:

TEST ORGANISM
- Common name: Midge (Chironomus riparius)
- Breeding conditions: The purchased organisms arrived as ten egg masses and were held for four days at ambient temperature in water from the same source as the water used during the test. During the holding period the temperature ranged between 19.6 and 20.8°C, pH ranged between 8.6 and 8.7, and dissolved oxygen ranged between 8.8 and 9.2 mg/L. Midges appeared normal during the holding period.
- Handling of egg masses and larvae: Approximately 24 hours prior to the addition of test substance, one to three day old larvae were collected from at least three separate egg masses and impartially added one and two at a time into test chambers until each of the appropriate test chambers contained 20 organisms. All transfers were made below the air/water interface using a wide bore pipette. Organisms were added to all test chambers with the exception of the 1-hour replicates used for analytical and the Day 0 replicate used for pH measurements in sediment.
- Age of animals at beginning of exposure: 1 -3 one day old larvae
- Feeding during test: Chironomids were fed 10 - 30 mg of ground rabbit pellets three times per week throughout the test.

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Remarks:

freshwater obtained from a well approximately 40 meters deep.

Type of sediment:

artificial sediment

Limit test:

no

Duration:

28 d

Exposure phase:

larvae from first generation (P)

Hardness:

Range: 132 – 144 mg/L as CaCO3 (Mean: 136 mg/L as CaCO3)

Test temperature:

18.5 - 20.9°C

pH:

Overlying water: 8.1 - 8.7, sediment: 7.1 - 7.9

Dissolved oxygen:

=6.6 mg O2/L (73% of saturation)

Salinity:

Range: 182 – 184 mg/L as CaCO3 (Mean: 183 mg/L as CaCO3)

Conductivity:

Range: 310 – 315 µmhos/cm (Mean: 311 µmhos/cm)

Nominal and measured concentrations:

Nominal test concentrations: 0.44, 0.88, 1.8, 3.5 and 7.0 mg a.s./L alongside a negative control and solvent control.
Measured concentrations of Desmedipham were 116, 118, 129, 103 and 111% of nominal values, respectively.

Details on test conditions:

- Groups of 20 midges in four replicates (total 80 midges in each treatment and control group) were exposed to five test concentrations, 0.44, 0.88, 1.8, 3.5 and 7.0 mg a.s./L, a negative control (dilution water) and a solvent control (0.1 ml acetone/L) for 28 days.
- The test chambers were observed three times per week during the first 13 days of the test to make visual assessments of any abnormal behaviour (e.g., leaving sediment, unusual swimming). During the period of expected emergence following Day 13, the test chambers were observed on a daily basis and the sex and numbers of fully emerged midges were recorded. After identification, the midges were removed from the test chambers.
- Also, five additional test chambers were added to each of the negative and solvent controls and the low, middle and high treatment levels for analytical sampling of water and sediment. Samples were analysed LC/MS/MS and HPLC/UV.
- The sediment used in the test was composed of 12.5% sphagnum peat moss, 18% kaolin clay, and 69% industrial quartz sand (to reach the recommended org C).
- The temperatures were within the 20 ± 2°C, dissolved oxygen concentrations were =6.6 mg O2/L (73% of saturation) throughout the test. Measurements of pH ranged from 8.1 to 8.7 in the overlying water and 7.1 to 7.9 in the sediment during the test. The photoperiod was 16 hours of light and 8 hours dark with a light intensity of 285 Lux at test initiation.

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 3.34 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

other: emergence rate and development rate

Remarks on result:

other: based on amended report

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

>= 7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: emergence rate and development rate

Remarks on result:

other: based on initial study report

Details on results:

Analytical results
Measured concentrations of desmedipham in concentrated stock solutions collected at the start of the test from the 0.44, 0.88, 1.8, 3.5 and 7.0 mg a.s./L treatment groups were 116, 118, 129, 103 and 111% of nominal values, respectively. Measured concentrations of desmedipham in the overlying water one hour after dosing in 0.44, 1.8, and 7.0 mg a.s./L test concentrations were 66.6, 78.3, and 47.7% of nominal, respectively. Four hours after dosing the respective measured concentrations were 28.9, 8.6, and 21.4% of nominal. One day after exposure, the corresponding desmedipham concentrations were less than 0.3% of nominal indicating that desmedipham degraded very quickly from the overlying water. An approximate mass balance for desmedipham was calculated at 1 and 4 hours after application from measured concentrations of desmedipham and EHPC in overlying water, pore water and sediment. After one hour, the amount of desmedipham that was accounted for in the 0.44, 1.8, and 7.0 mg a.s./L test concentrations was 112, 118, and 125% of nominal expressed as desmedipham /desmedipham equivalents.

Biological results
Emergence was first noted on Day 13 of the test. There were occasional observations of larvae leaving the sediment and climbing the walls of test chambers from days 6 through 20 in both control and treatment groups, although it was not considered to be treatment-related. There were isolated incidences of mortality after emergence although were not considered to be treatment-related, since they were rare occurrences and did not follow a concentration dependent pattern. There were significant differences between the solvent and negative controls for both development time and development rates all comparisons were made between the solvent control and treatment groups. The EC50 value based on % emergence of midges exposed to overlying water spiked with desmedipham was > 7.0 (95% confidence intervals not applicable) mg a.s./L, the highest nominal concentration tested. There were no treatment-related effects observed on mean emergence ratios, development times and development rates. Therefore, the NOEC was =7.0 mg a.s./L and the LOEC was > 7.0 mg a.s./L based on nominal concentrations (sum of desmedipham and EHPC).

However, according to the amended report, M-545523-01-1, the endpoint was re-calculated based on initially measured concentrations of DMP. The NOEC is based on the highest test concentration, corresponding to an initially measured concentration of =3.34 mg a.s./L.

See "Attachments" in "Overall remarks, attachments" for tables and appendix.

Validity criteria fulfilled:

yes

Remarks:

The emergence in control at end of study was = 70 %, adult emergence occurrence in the control vessels was between 12 – 23 days, and the required water temperature variation during the test (°C) was ± 1°C.

Conclusions:

The EC50 value based on percent emergence of midges (Chironomus riparius) exposed to overlying water spiked with Desmedipham was greater than 7.0 mg a.s./L, the highest nominal concentration tested. There were no treatment-related effects observed on mean emergence ratios, development times and development rates. Therefore, the LOEC was >7.0 mg a.s./L and the NOEC was =7.0 mg a.s./L. However, the NOEC value was re-calculated based on initially measured concentrations of DMP. The NOEC is based on the highest test concentration, corresponding to an initially measured concentration of =3.34 mg a.s./L.

Executive summary:

The chronic toxicity of desmedipham to the sediment dwelling larvae of the midge Chironomus riparius were determined in a 28-day study. The nominal initial test concentrations were 0.44, 0.88, 1.8, 3.5 and 7.0 mg a.s./L overlying water, alongside a negative control and a solvent control. Desmedipham was degraded almost completely within 24 h, but the approximate mass balance showed that dosing was correctly performed. Based on nominal concentrations of sum of desmedipham and EHPC a NOEC value of ≥7.0 mg/L was obtained. Based on geomean of initially measured concentrations the NOEC corresponds to an initially measured concentration of ≥3.34 mg a.s./L.

Reference 2

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-08-13 to 2002-12-19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: BBA - Effects of plant protection products on the development of sediment-dwelling larvae of Chironomus riparius in a water-sediment system

Version / remarks:

1995

Deviations:

not specified

GLP compliance:

yes

Specific details on test material used for the study:

The test item had the appearance of a white crystalline powder.

Analytical monitoring:

yes

Details on sampling:

Samples taken from the water column of the test vessels on days 0, 7 and 21 were analysed for the concentrations of DMP and its hydrolysis metabolite, EHPC. Samples were taken from the top, the middle and the lowest concentration on day 0 (approx. one hour after dosing) and from all concentrations on days 7 and 21. The results of the test are reported in terms of nominal initial concentrations of the test item, DMP.

Vehicle:

yes

Remarks:

Acetone (0.1 ml_/L medium)

Details on sediment and application:

Test water
Deionized water used as a basis in all toxicity tests at the testing facility is obtained from a special water supply inside the factory and can be drawn from tap. This water is additionally filtered by a deionization unit and a charcoal filter within the laboratory before use. Test water (for a detailed description of the ingredients see Table 6.2) was an artificial mineral medium M4 (Elendt 1990), modified. To prevent precipitation during preparation of medium, the aliquots of the application mixture were dosed into 200 - 250 mL deionized water and then topped up to 300 mL. This medium was prepared and allowed to reach test temperature prior to use. The characteristics of test water are presented in tables 6.3 and 6.4.

Test sediment
The artificial sediment was prepared 10 days before introduction of the test organisms (i.e., 10 days before application of the test item). The artificial sediment was prepared from: 10% 1335 g dried and finely ground, and sieved sphagnum peat (residual moisture content of 11.2% taken into calculation), 20% 2.4 kg kaolin clay, and 70% 8.4 kg quartz sand.
These constituents were blended by a rapid mixer. 360 g Calcium carbonate (CaCO3) were used to adjust the pH of this medium to 7.2. A small sample was taken from this mixture, and the moisture content was determined by means of a scale with a drying device. The residual moisture content of this substrate was 1.13%. After addition of 5.38 L of deionized water and blending by hand the actual moisture content was determined at 31.14%.

On day 0, appropriate aliquots of the stock solutions for the test item concentrations and the control (Table 6.1) were added to the overlying water directly below the water surface with a glass pipette followed by careful mixing of the water without disturbing the sediment.

Test organisms (species):

Chironomus riparius

Details on test organisms:

TEST ORGANISM
- Common name: Midge (Chironomus riparius)
- Breeding conditions: The test species were bred in the testing facility. The rearing vessels (14 cm diameter, 7 cm height) were placed in a cage (60 cm x 60 cm surface, 50 cm height), with a gauze on the inside of the cage to confine emerged adults. The rearing vessels dishes contained a 2-3 cm layer of quartz sand and a 2 - 3 cm high layer of reconstituted water (cf. 2.5.), which was gently aerated. Culture in a specific rearing vessel was started by placing 2- 4 egg masses into the water. The hatched larvae were fed with an aqueous suspension of fish food. After 2 - 3 weeks the imagines emerged. After mating, female imagines deposited egg masses on the water surface from where they were taken to start a new culture or to perform a test. The culture conditions were 20 ± 2°C and a 16:8 hours light-dark-cycle with 60 minutes transition periods. Water used for breeding was the same as used in the test
- Handling of egg masses and larvae: The L1 larvae used in the study were obtained by transferring egg masses in small crystallising dishes with culture medium. After 2 to 3 days the L1-larvae hatched and were transferred to the test beakers.
- Age of animals at beginning of exposure: For the study, animals of the first larval stage (L1) were used.
- Feeding during test: The hatched larvae were fed with an aqueous suspension of fish food

Study type:

laboratory study

Test type:

static

Water media type:

other: artificial mineral medium M4 (Elendt 1990), modified.

Type of sediment:

artificial sediment

Limit test:

no

Duration:

28 d

Exposure phase:

larvae from first generation (P)

Hardness:

2.68 mmol/L (Ca2+ + Mg2+)

Test temperature:

19.7 - 20.2°C

pH:

7.3 to 8.3 (Mean: 7.8)

Dissolved oxygen:

6.5 - 8.9 mg/L (Mean: 8.1 mg/L)

Conductivity:

656 - 795 uS/cm (Mean: 728 uS/cm)

Nominal and measured concentrations:

Nominal concentrations: 0.125, 0.25, 0.5, 1.0 and 2.0 mg/L, alongside an untreated control and a solvent control.
Mean measured concentrations: 0.087, 0.091, 0.313. 0.501, and 0.965 mg/L.

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 3000 ml glass beakers
- Weight of wet sediment with and without pore water: 500 g (wet weight) of sediment
- Overlying water volume: 2.5 L
- Depth of sediment and overlying water: The bottom of each test vessels was covered with 500 g (wet weight) of sediment, providing a layer of approximately 2 cm height. The water depth above the sediment layer was approximately 20 cm.
- Aeration: yes
- Aeration frequency and intensity: Gentle aeration was provided with a glass Pasteur pipette situated approximately 1 cm above the sediment layer
- Replacement of evaporated test water, if any: To prevent precipitation during preparation of medium, the aliquots of the application mixture were dosed into 200 - 250 mL deionized water and then topped up to 300 mL.

EXPOSURE REGIME
- No. of organisms per container (treatment): 25 larvae
- No. of replicates per treatment group: 4 replicates
- No. of replicates per control / vehicle control: 4 replicates

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

0.14 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: based on amended report

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: based on initial study report

Details on results:

Test item concentrations
Detailed results are presented in Tables 6.6. On day 0 the test results for the nominal concentration levels 0.125 mg/L and 0.5 mg/L indicated that the parent compound was rapidly hydrolysed under the test conditions, with measured concentrations below the LOD and 43% of nominal respectively within the first hour of dosing. That this was due to hydrolysis could be seen from the fact that, there were correspondingly high concentrations of the hydrolysis metabolite EHPC at the same time points. Indeed, when the concentrations of parent and metabolite were combined it was seen that initial mean measured concentrations at 0.125 and 0.5 mg/L were within 80-120% of the nominal concentrations. For the concentration level 2.0 mg/L, hydrolysis was also evident, although in this case the combined concentration of DMP and EHPC was also low (35% of the nominal concentration) and indicated that the low recovery was for reasons other than just hydrolysis.

On day 7 all results (sum of DMP and EHPC) were in the range of 73.8 - 80.0% of the respective nominal concentration level, including the top concentration of 2.0 mg/L. At this concentration, precipitation had been observed after introduction of the test item at exposure initiation. This observation in combination with the recovery of the hydrolysis metabolite after 7 days (79.0% of nominal DMP concentration) demonstrated that the low initial recovery at the top concentration was not due to incorrect dosing but a consequence of exceeding the limit of solubility of the test item. Therefore the results of the study are reported in terms of nominal but analytically confirmed initial concentrations.

On day 21 for the concentration levels 0.125 mg/L, 1.0 mg/L and 2.0 mg/L the results (sum of DMP and EHPC) were within 22.5 - 33.4% of the nominal concentration. For the concentration levels 0.25 mg/L and 0.5 mg/L no more DMP or EHPC were found. Such decreasing concentrations in the further course of this test can be regarded as natural dissipation in a water-sediment system.

The variability for all concentrations was >1.5 due to the different levels found for days 0, 7 and 21. The recovery rates were in the range of 100%, indicating the absence of analytical problems.

Validation results and chromatograms demonstrated sufficient reliability of the method for the desired application: The lowest concentration level was above the LOQ and all concentrations of the analyte solution prepared for HPLC were within the linearity range. Repeatability precision expressed by a mean CV of duplicate determinations was <20% for all concentration levels and compounds. Accuracy was within 80-120% recovery with a CV <20% for all compounds. The specificity of the method was sufficient: The chromatograms displayed no matrix interference > LOQ of the determined compounds of which the identities were established by co-chromatography with the corresponding certified reference substances.


Biological effects
Individual values for different endpoints (sum of males, sum of females, sum of both sexes, emergence ratio ER, transformed ERarc, development rate) are presented in Table 6.8. Basic statistics (mean, standard deviation, minimum, maximum) for each endpoint per treatment levels are presented in Table 6.9 and illustrated in Figures 7.5 to 7.8. Table 6.10 gives a survey of the statistical differences between the control and the treatment levels regarding the biological endpoints evaluated.

In all treatment groups including the controls, first emergence of males and females was observed after 14 and 15 days, respectively. Last emergence occurred at day 21 (both males and females). The total number of emerged midges varied between 21 and 25 over all replicates.

The statistical analysis of emergence data per sex was not more sensitive than for both sexes combined. Transformation of emergence data was not considered necessary since the untransformed data met the assumption of homogeneity of variances (Bartlett's test).

The determination of the effect concentrations was based on the emergence ratio, the most sensitive parameter identified in this study. The emergence ratio recorded for the top concentration was statistically significantly different from both the untreated control and the solvent control. Consequently, the LOEC (lowest observed effect concentration) for the emergence ratio was established at 2.0 mg/L.

No further statistically significant difference was observed in any parameter including the development rate. Therefore, the NOEC (highest concentration without treatment related effects on the emergence ratio or the development rate of Chironomus riparius larvae) was 1.0 mg a.s./L of overlying water.

However, according to the amended report, M-545523-01-1, since the NOEC-level was not analysed at test initiation, the mean recovery of all concentration levels is used to re-calculate the NOEC-level, using the geomean of initially measured concentrations, i.e. 14% * 1.0 mg a.s./L = 0.14 mg a.s./L

See "Attachments" in "Overall remarks, attachments" for tables and figures.

Validity criteria fulfilled:

yes

Remarks:

The emergence in control at end of study was = 70 %, adult emergence occurrence in the control vessels was between 14 – 21 days, and the required water temperature variation during the test (°C) was ± 1°C.

Conclusions:

A 28-day study to determine the effects of desmedipham, substance, technical to Chironomus riparius in a sediment water system was performed according to the BBA method (1995). The concentration without any observed effects (NOEC) was established at the nominal but analytically confirmed initial concentration of 1.0 mg/L. However, the NOEC value was recalculated. Since the NOEC-level was not analysed at test initiation, the mean recovery of all concentration levels is used to re-calculate the NOEC-level, using the geomean of initially measured concentrations, i.e. 14% * 1.0 mg a.s./L = 0.14 mg a.s./L.

Executive summary:

The chronic toxicity of desmedipham to the sediment dwelling larvae of the midge Chironomus riparius were determined in a 28-day study. The nominal initial test concentrations were 0.125, 0.25, 0.5, 1.0 and 2.0 mg/L overlying water, alongside an untreated control and a solvent control. The results were evaluated based on the percentage of successfully emerged midges (emergence ratio), and on the time to emergence (development rate). The emergence success was 89% or more at all test concentrations, though at the top concentration of 2.0 mg/L emergence was significantly (statistically) lower than the controls. The development rate did not differ significantly at any treatment level. The highest concentration without any observed effects (NOEC) was established at the nominal initial concentration of 1.0 mg/L. The recalculated NOEC value based on geometric mean was 0.14 mg a.s./L.

Description of key information

The aim of the study was to determine the influence of the test item on emergence and development of Chironomus riparius for 28-days in a static water-sediment system (spiked water exposure). The NOEC (emergence) value based on nominal initial concentrations in the overlying water and the emergence ratio was 0.14 mg/L (geometric mean measured).

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
Chironomus riparius (chironomid)	28-d water spiked NOEC = 1.0 mg a.s./L (nominal) 28-d water spiked NOEC = 0.14 mg a.s./L (geomean measured)	Key study	Ebeling & Ludwig (2002)
Chironomus riparius (chironomid)	28-d water spiked NOEC ≥7.0 mg a.s./L (nominal) 28-d water spiked NOEC ≥3.34 mg a.s./L (initial measured)	Supporting study	Krueger et al. (2005)