Desmedipham

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

fish early-life stage toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-03-22 to 2014-03-13

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 210 (Fish, Early-Life Stage Toxicity Test)

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EPA 540/9-82-024. Pesticide Assessment Guidelines, Subdivision E - Hazard Evaluation: Wildlife and Aquatic Organisms.

Version / remarks:

1982 - USEPA, EPA 540/9-82-024. Washington, D.C. 86 pp.

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1400 (Fish Early-life Stage Toxicity Test)

Version / remarks:

1996

Deviations:

no

Principles of method if other than guideline:

The above mentioned guidelines were harmonized for various test parameters (i.e. temperature, light, etc.) to achieve optimal environmental conditions for the test organism. Scientific discretion was implemented where guideline parameters do not fully converge.

GLP compliance:

yes

Specific details on test material used for the study:

The test material is a white powder.

Analytical monitoring:

yes

Details on sampling:

During the exposure period test solution samples were collected at least weekly from two alternating replicate test vessels to confirm exposure concentrations by HPLC.

Vehicle:

yes

Remarks:

Acidified Dimethylformamide

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION

- Method of mixing: Sonication
- Differential loading: The solvent load in the test system was 0.1 ml/L.
- Controls: A control and a solvent control (Acidified Dimethylformamide).
- Solvent: Acidified Dimethylformamide (2% phosphoric acid solution, pH<4)
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): No precipitate
- Other relevant information: Acidified Dimethylformamide (2% phosphoric acid solution, pH<4), was used to prepare the stock solutions in order to stabilize the test substance. Stock solutions were prepared as needed (approximately every 2 weeks). The appropriate amount of compound was weighed into a volumetric flask (corrected for percent a.s.). The flask was brought to volume with acidified Dimethylformamide and sonicated for 5 minutes.

An all glass 2-L modified proportional diluter system was used for intermittent delivery of test solutions to test chambers. Splitter cups were used to equally divide (±10%) test solutions between replicates at each level. The test material and solvent were delivered to the appropriate mixing vessels using a Hamilton Microlab 500 series syringe pump and a Hamilton Microlab 600 series syringe pump, respectively. Once during each diluter cycle, a series of three injections were delivered to the appropriate location within the diluter system.

The toxicant mixing box received a 426-µL injection of the 7.00 g a.s./L stock solution to 4.26 L dilution water (the nominal concentration in the toxicant mixing chamber was 0.700 mg a.s./L). The solvent control received a 200 µL injection of acidified DMF into the appropriate diluter cell that contained a volume of 2.0 L of dilution water.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

TEST ORGANISM
- Common name: Rainbow trout (Oncorhynchus mykiss)

METHOD FOR PREPARATION AND COLLECTION OF FERTILIZED EGGS
- Numbers of parental fish (i.e. of females used to provide required number of eggs):
- Method of collection of fertilised eggs: Unfertilized eggs and milt were collected and acclimated from 2.5°C to a temperature of approximately 10°C over a period of 2 hours. Upon acclimation, eggs were transferred to a dry stainless steel bowl. The milt was mixed with the eggs with an autoclaved goose feather for about 3 minutes. This was followed by the addition of the fertilization diluent (10°C). The eggs and milt were gently stirred for about 1 minute to facilitate fertilization.

Test type:

flow-through

Water media type:

other: spring water blended with reverse osmosis

Limit test:

no

Total exposure duration:

92 d

Hardness:

38 - 54 mg/L as CaCO3

Test temperature:

10.1 - 10.7°C (mean: 10.3°C)

pH:

7.4 - 8.0

Dissolved oxygen:

9.0 - 11.2 mg/L

Salinity:

35 - 46 mg/L as CaCO3

Conductivity:

128 - 160 µmhos/cm

Nominal and measured concentrations:

Nominal concentrations (mean measured) were: control (<0.006), solvent control (<0.006), 0.0667 (0.0760), 0.120 (0.115), 0.216 (0.203), 0.389 (0.417) and 0.700 (0.711) mg a.s./L.

Details on test conditions:

TEST SYSTEM
- Egg cups: One oscillating egg cup per replicate placed in each replicate through the egg hatching phase. For determination of the fertilization success four additional egg cups were placed into the control chamber replicates.
- Study Area: Test bath with liquid circulated temperature control.
- Test vessel: All Glass
- Test Vessel Size: 8.4-L
- Testing Volume: 7-L (21.6 x 12.7 x 25.5 cm)
- Aeration: None
- Type of flow-through: proportional diluter
- Renewal rate of test solution (frequency/flow rate): approximately 10 turnovers/day.
- Organisms per Replicate: 35 eggs at initiation, thinned to 15 alevins after hatching phase.

TEST MEDIUM / WATER PARAMETERS
- Source of dilution water: Soft processed water (blended spring and reverse osmosis waters).

OTHER TEST CONDITIONS
- Photoperiod: 16 hours light/8 hours dark with 30 minutes dawn/dusk transition period.
- Light intensity: 488 - 764 lux

Key result

Duration:

92 d

Dose descriptor:

NOEC

Effect conc.:

0.076 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: based on growth (length and dry weight)

Key result

Duration:

92 d

Dose descriptor:

LOEC

Effect conc.:

0.115 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: based on growth (length and dry weight)

Duration:

92 d

Dose descriptor:

EC10

Effect conc.:

0.146 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

other: dry weight

Remarks on result:

other: recalculated EC10

Duration:

92 d

Dose descriptor:

EC10

Effect conc.:

0.152 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: growth (dry weight)

Remarks on result:

other: reported in the original report

Details on results:

Analytical results
Mean measured recoveries of sum of desmedipham and EHPC were within the range of 94 to 114% of the nominal concentrations. The results are based on the mean measured concentrations sum of of desmedipham and EHPC.
The endpoint was re-calculated based on arithmetic mean measured concentrations of desmedipham, and this is documented in report M-545521-01-1. See "Attachments" in "Overall remarks, attachments" for the recalculated endpoint.

Behavioral and Morphological Observations
Observations of fish were recorded daily throughout the study. Compound related sub-lethal effects were observed in the three highest test levels with 0.203, 0.417, and 0.711 mg a.s./L. Fish in these test levels were pale, quiescent, on bottom of the tank, displayed vertical swimming behaviour, and were dark in coloration. One fish in the lowest test level had a bent spine, which was transient in nature (study days 39-45) and is not considered to be compound related. All other fish including the control groups showed normal behaviour and were without malformations.

Egg Viability
Egg viability was checked 11 days after fertilization utilizing 4 additional egg cups, each containing 50 eggs, that were placed in each control chamber at experimental start. The viability was 90, 92, 88, and 94 percent, respectively, with a mean viability of 91 percent (Table 9).

Percent Hatch (Time to Hatch)
Egg hatching began on study day 28 and continued until study day 32. Day 32 represented the day in which > 90% of the viable eggs completed hatching and was the most representative day for the hatch data analysis. The day 32 mean percent hatch ranged from 52.1 to 89.3%. The day 32 mean percent hatch, corrected for viability, ranged from 57.3 to 97.9%. Statistical analysis indicated that percent hatch was significantly different from pooled controls in the 0.711 mg a.s./L test level.

Percent Swim-up (Time to Swim-up)
Swim-up began on study day 46 and was completed on study day 55 for the control groups and the test levels with 0.0760, 0.115, and 0.203 mg a.s./L. Due to high mortality the two highest test levels were excluded from statistical analysis. Day 55 represented the day in which > 90% of the control fish were swimming up and was the most representative day for analysis. Swim-up was not significantly different from pooled controls for the test levels with 0.0760, 0.115, and 0.203 mg a.s./L.

Fry Survival (Post-Hatch Success)
Fry survival was analyzed at test termination on study day 92. Mean percent fry survival ranged from 0 to 100%. Data analysis showed statistically significant difference in comparison to the pooled control data in the test levels with 0.203, 0.417 and 0.711 mg a.s./L.

Growth
At test termination (study day 92), the fish were sacrificed and standard length and dry weight measurements were collected. The mean lengths ranged from 28.1 to 37.6 mm. Mean dry weights for fish ranged from 47.0 to 118.7 mg. Data analysis showed statistically significant difference in comparison to the pooled control data in the test levels with 0.115 and 0.203 mg a.s./L for standard length and dry weight. Due to high mortality in the test levels with 0.417 and 0.711 mg a.s./L, these groups were excluded from statistical analysis.

The 92-day exposure to desmedipham technical resulted in a NOEC of 0.076 mg a.s./L and a LOEC of 0.115 mg a.s./L based on growth (length and dry weight). The lowest EC10 (95% C.I.) was determined to be 0.152 (0.129 – 0.172) mg a.s./L based on growth (dry weight). The EC10 values reported in the original report were calculated on the basis of mean measured concentrations of desmedipham and its metabolite EHPC. Therefore, it was recalculated on the basis of arithmetic mean measured concentrations of desmedipham only, and this is documented in report M-582216-01-1. The recalculated EC10 value obtained was 0.146 mg a.s./L. (See "Attachments" in "Overall remarks, attachments").

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

Validity criteria fulfilled:

yes

Conclusions:

Validity criteria for this study were met. The mean hatching success in the controls was 91.0% (corrected for viability). The post hatch average survival (post-hatch success) of controls was 99.2% with survival rates ranging from 93.3 – 100% for each control replicate. Dissolved oxygen was >60% of the air saturation value. The water temperature did not differ by more than 1.5°C between test chambers or between successive days at any time during the test, and was within the temperature ranges specified for the test species. The 92-day exposure to Desmedipham technical resulted in a NOEC of 0.0760 mg a.s./L and a LOEC of 0.115 mg a.s./L based on growth (length and dry weight). Endpoints were based on mean measured concentrations of Desmedipham + EHPC. The recalculated EC10 value obtained was 0.146 mg a.s./L, and this is based on arithmetic mean measured concentrations of desmedipham only.

Executive summary:

The early life stage toxicity of desmedipham technical to rainbow trout (Oncorhynchus mykiss) was determined. Fish were exposed to a range of nominal concentrations of 0.0667, 0.120, 0.216, 0.389, and 0.700 mg a.s./L alongside a water and solvent control.  The 92-day exposure to Desmedipham technical resulted in a NOEC of 0.0760 mg a.s./L and a LOEC of 0.115 mg a.s./L based on growth (length and dry weight). Endpoints were based on mean measured concentrations of Desmedipham + EHPC. The recalculated EC₁₀ value obtained was 0.146 mg a.s./L, and this is based on arithmetic mean measured concentrations of desmedipham only.

Description of key information

A Fish early life stage was conducted to estimate the long-term toxicity of Desmedipham to Rainbow Trout (Oncorhynchus mykiss). The NOEC (92 h) was determined to be 0.076 mg/L.

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
Oncorhynchus mykiss (rainbow trout)	NOEC (92 h) = 0.076 mg a.s./L (arithmetic mean measured) LOEC (92 h) = 0.115 mg a.s./L (arithmetic mean measured) EC10 (92 h) = 0.146 mg a.s./L (geomean measured)	Key study	Matlock & Moore (2014)
Oncorhynchus mykiss (Salmo gairdneri, rainbow trout)	NOEC (21 d)  ≥1.2 mg a.s./L (mean measured)	Prolonged toxicity study is not a data requirement. Furthermore, the study is not considered valid because the active substance was not analysed from test medium, instead the desmedipham was hydrolysed to the metabolite before analysis. Hence, no NOEC value, which would be based on desmedipham content, could be obtained.	Wuethrich (1991)
Oncorhynchus mykiss (rainbow trout)	NOEC (28 d) = 0.20 mg a.s./L (nominal)	Prolonged toxicity study is not a data requirement. Furthermore, the study is not considered valid as the effect of desmedipham exposure on the growth of the test organisms cannot be attributed to either the parent or the hydrolysis product alone but to a combination of both.	Sewell et al. (1994)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

NOEC

Effect concentration:

0.076 mg/L