Fenamiphos

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: FIFRA; SLS protocol # 091087/DM-LC.FIF

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Method: water samples were removed and analyzed for the 14C labelled test item on days 0, 4, 7, 14 and 21 from two replicate vessels of each test concentration and the controls

Vehicle:

yes

Remarks:

acetone

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Diluter stock solutions of 0.0197 mg a.i./mL were prepared by diluting 12 mL of a 14C-test item superstock (0.0822 mg a.i./mL) with acetone to a total volume of 50 mL. During this study stock solutions were prepared on test days -18 and 3. A 200-mL Mount and Brungs (1967) proportional diluter, calibrated to provide 50 % dilutions between adjacent nominal concentrations, delivered the dilution water and the test item to the test vessels during the chronic toxicity test. The diluter was constructed entirely of glass and silicone tubing, stoppers and sealant. The diluter system was equipped with a 30-mL gas-tight HamiltonR syringe which delivered 0.0094 mL of the test item stock solution (0.0197 mg a.i./mL) into 395 mL of dilution water in the system's mixing chamber during each diluter cycle. In order to completely solubilize the test material in the dilution water the solution within the mixing chamber was continuously stirred using a magnetic stirrer. This 395-mL solution (nominal concentration of 0.47 µg a.i./L) served as the highest treatment level from which calibrated volumes were diluted to provide the 50 % nominal concentration gradient (0.47 to 0.029 µg a.i./L). Five-centimeter (cm) lengths of 1-millimeter (inside diameter) glass capillary tubing were inserted through silicone stoppers in the mixing/splitting chambers of the diluter and into the test solution delivery tubes. This tubing served to restrict the flow of the test solutions, minimizing potentially stressful turbulence in the test vessels and providing equal distribution of the test solutions to the replicate vessels.
- Controls: negative control, solvent control
- Chemical name of vehicle: acetone
- Concentration of vehicle in test medium: 24 µg/L (final solution)
- Test concentration separation factor: 2
- Evidence of undissolved material: no

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Age at study initiation (mean and range, SD): >= 24 hours
- Weight at study initiation: not measured
- Length at study initiation: not specified
- Stage and instar at study initiation: first instar, juvenile
- Method of breeding: laboratory culture; static renewal conditions (20 ± 2 °C) in well water fortified to a total hardness of 160-180 mg/L CaC03, water quality same as test, fed daily a combination of green algae (Ankistrodesmus falcatus) and a yeast suspension, plus SelcoR, a commercial mixture of fatty acids and protein, was added weekly to each vessel.
- Feeding during test: yes, fed a diet consisting of a suspension of Fleischmann’s yeast (5 mg/mL), a suspension of green algae (Ankistrodesmus falcatus; 4 x 10^7 cells/mL) and SelcoR (a commercial mixture of proteins and fatty acids, 0.6 mg/mL); feed introduced at a rate of 0.5 mL of yeast suspension, 3.0 mL of algal suspension and 1.0 mL of SelcoR food supplement three times daily on weekdays and twice daily on weekends and holidays

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

Post exposure observation not performed

Hardness:

170 - 180 mg/ CaCO3

Test temperature:

20 °C

pH:

7.9 - 8.4

Dissolved oxygen:

8.5 - 8.7 µg a.i./L

Salinity:

not applicable

Conductivity:

500 µmhos/cm

Nominal and measured concentrations:

Nominal: 0.029, 0.058, 0.12, 0.23 and 0.47 µg a.i./L; measured: 0.032, 0.066, 0.12, 0.24, and 0.49 µg a.i./L (mean measured), 85.0 ± 7.17 % of nominal (mean value)

Details on test conditions:

TEST SYSTEM
- Test vessel: battery jars
- Material, size: glass, 1.8 L capacity
- Aeration: no
- Type of flow-through: proportional diluter
- Renewal rate of test solution: 6 aquarium volumes per 24-hour period in order to provide a 90 % test solution replacement rate of approximately 9 hours
- No. of organisms per vessel: 10
- No. of vessels per concentration: 4
- No. of vessels per control: 4
- No. of vessels per vehicle control: 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: 1900-liter batches by fortifying well water according to the formula for hard water (ASTM, 1980) and filtering it through an Amberlite XAD-7 resin column to remove any potential organic contaminants. Generally, several batches of water were prepared each week. The frequency at which the dilution water was prepared depended on the requirements of the laboratory. Fortified water was discarded if not used within 14 days of preparation. This water generally had a total hardness and alkalinity as calcium carbonate (CaCO3) of 160-180 mg/L and 110-130 mg/L, respectively, a pH range of 7.9-8.3, a temperature of 20 ± 1 °C and a specific conductivity of 400-600 micromhos per cm (µmhos/cm). Water quality parameters were measured on each batch of fortified water prior to use. The ability of several daphnid species to survive and reproduce over several generations of culture in this water source and periodic scans for PCB and pesticide contamination confirmed that the dilution water was of acceptable quality.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours light, 8 hours darkness
- Light intensity: Durotest Optima and Gro-LuxR fluorescent lights, 34 to 60 footcandles

EFFECT PARAMETERS MEASURED: mortality , number of offspring/female and the body lengths of parent animals

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study: performed
- Test concentrations: 1.0, 0.50, 0.25, 0.13, 0.063 µg a.i./L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.12 µg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.24 µg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Remarks:

offspring / female

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

24 µg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Remarks:

Offspring / female

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

0.12 µg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth

Remarks on result:

other: Body length of parent animals

Details on results:

- Behavioural abnormalities:
- Observations on body length: After 21 days of exposure, organism growth, determined as body length, was the most sensitive indicator of the toxicity of the test item to Daphnia magna in the concentration range tested. Growth in the second highest treatment level (0.24 µg a.i./L) was determined to be 4.2 ± 0.1 mm. This was significantly different (P < 0.05) from the pooled control organisms (4.6 ± 0.3 mm). The mean body length in the remaining treatment levels (0.12, 0.066 and 0.032 µg a.i./L) was 4.5 mm which was statistically comparable to the body length of the pooled control daphnids.
- Other biological observations: none
- Mortality of control: yes, one daphnid of 20 (98% survival after 21 days of exposure)
- Other adverse effects control: not reported
- Immobilisation of control: not reported
- Abnormal responses: not reported
- Any observations that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

positive control not performed

Reported statistics and error estimates:

not reported

Table 1: Mean measured concentrations of 14C-labelled test item established during the 21-day chronic exposure of Daphnia magna

Nominal concentration (µg a.i./L)	Mean measured concentration (SD) (µg a.i./L)	Percent of nominal	N
0.47	0.049 (0.041)	104	7
0.23	0.24 (0.034)	104	7
0.12	0.12 (0.0079)	100	8
0.058	0.066 (0.019)	114	8
0.029	0.032 (0.0052)	110	8

 

Table 2: Measured concentrations of Fenamiphos Technical during the 21-day chronic exposure of Daphnia magna. Results are based on High Pressure Liquid Chromatography (HPLC)

Nominal concentration (µg a.i./L)	Measured concentrations (µg a.i./L)
	Day 0	Day 4	Day 7	Day 14	Day 21
0.47	0.63	0.57	0.56	0.53	0.47
	0.77	0.54	0.65	0.62	0.51
QA #1a	86.5	110	130	83.8	103
QA #2	103	111	109	104	98.2
QA #3	103	126	120	114	98.3

a: Quality Assurance sample. Values presented represent the percent recovered from a nominal fortified concentration.

 

Table 3: Weekly mean percentage survival of daphnids (Daphnia magna) during the 21-day chronic exposure

Mean measured concentration (µg a.i./L)	Mean percentage survival (S.D.)
	Day 7	Day 14	Day 21
0.49	100 (0)	8 (5)	0 (0)a
0.24	100 (0)	98 (5)	93 (10)
0.12	100 (0)	95 (6)	93 (5)
0.066	100 (0)	100 (0)	95 (6)
0.032	100 (0)	98 (5)	90 (12)
Solvent Control	100 (0)	98 (5)	93 (10)
Control	100 (0)	98 (5)	98 (5)
Pooled Control	100 (0)	98 (5)	98 (8)

a: Statistically significantly (P < 0.05) different from the pooled control data.

 

Table 4: Cumulative number of offspring produced per female Daphnia magna during the 21-day chronic exposure

Mean measured concentration (µg a.i./L)	Mean (Standard Deviation) Cumulative Number of Offspring/Female
	Day 7	9	11	14	16	18	21
0.49	0 (0)	8 (4)	15 (7)	23 (9)	24 (9)	24 (9)	26 (11)
0.24	0 (0)	9 (2)	13 (4)	26 (9)	44 (5)	47 (5)	54 (5)
0.12	0 (0)	10 (30)	16 (9)	37 (19)	53 (14)	60 (14)	68 (18)
0.066	0 (0)	9 (5)	13 (6)	31 (11)	44 (7)	51 (7)	63 (7)
0.032	0 (0)	9 (8)	14 (8)	29 (15)	37 (19)	46 (20)	49 (24)
Solvent Control	0 (0)	10 (4)	17 (4)	33 (7)	41 (9)	47 (8)	53 (9)
Control	0 (0)	2 (1)	5 (1)	17 (6)	26 (9)	34 (12)	46 (16)
Pooled Control	0 (0)	6 (5)	11 (7)	25 (10)	33 (11)	41 (12)	49 (13)

a: Since the survival of the adult daphnids in the highest test concentration was significantly different (P < 0.05) from the survival of the pooled control organisms, reproduction data from this concentration (0.49 µg a.i./L) was not statistically compared to the controls

 

Table 5: Mean total body length of Daphnia magna after 21 days of exposure

Mean measured concentration (µg a.i./L)	Mean Body Length (mm)
0.49	a
0.24	4.2. (0.1)b
0.12	4.5 (0.2)
0.066	4.5 (0.1)
0.032	4.5 (0.1)
Solvent Control	4.7 (0.2)
Control	4.5 (0.2)
Pooled Control	4.6 (0.3)

a: No adults survived to day 21 in this treatment level
b: Significantly (P < 0.05) different from pooled control data

Validity criteria fulfilled:

yes

Conclusions:

In a chronic flow-through test according to FIFRA; SLS protocol # 091087/DM-LC.FIF with Daphnia magna the lowest NOEC of the test item was determined as 0.12 µg a.i./L.

Executive summary:

To determine the chronic effects of the test item on the survival, reproduction and growth of the daphnid (Daphnia magna) a study according to FIFRA; SLS protocol # 091087/DM-LC.FIF was carried out. The study was performed under continuous exposure, flowthrough conditions for a period of 21 days (one generation). Juvenile daphnids (<= 24 hours old, 40 daphnids per concentration) were exposed to nominal concentrations of 0.029, 0.058, 0.12, 0.23 and 0.47 µg a.i./L. The test item concentrations had been selected based on results of a range-finder study. Fortified well water according to the formula for hard water (ASTM, 1980) was used as dilution water and filtered through an Amberlite XAD-7 resin column in order to remove any potential organic contaminants.  The test item concentrations were analytically verified using a HPLC method and 14C screening scintillation measurements to be 0.032, 0.066, 0.12, 0.24, and 0.49 µg a.i./L (mean measured), i.e. to be 85.0 ± 7.17 % of nominal (mean value) throughout the test. The test solutions were supplied via a proportional diluter system with a flow rate of 6 aquarium volumes per 24-hour period in order to provide a 90% test solution replacement rate of approximately 9 hours. To prepare the stock solutions Acetone was used as vehicle. Test vessels were glass battery jars having a volume capacity of 1.8 L. Test solutions drained from the vessel through a 3.0 x 8.0 cm notch on the upper edge of the jars. The drains were covered with a NitexR 40-mesh screen to prevent loss of the daphnids. In addition to the five concentrations of the test item, dilution water control and solvent (acetone) control solutions were maintained during the study. The solvent control solutions contained the  greatest amount of acetone present in any treatment level (24 µg/L). All treatments and the controls were maintained in quadruplicate. The study was conducted in an air-temperature controlled room designed to maintain the test solution temperatures at 20 ± 1 °C. For additional temperature control the exposure vessels were partially submerged in a water bath maintained at the desired test temperature. Adult survival and  measurements of offspring production were made on days 1, 2, 4, and three times per week, (Monday, Wednesday and Friday), from day 7 through 21. The offspring were removed, counted and discarded. Test vessels were brushed to remove algal growth and the solution filtered through a fine mesh net a minimum of twice each week. At test termination the body length of all surviving daphnids in each treatment level and the controls was determined. Organism lengths were determined by measuring the daphnids from the top of the helmet to the base of the spine. The test organisms were fed a diet consisting of a suspension of Fleischmann1s yeast (5 mg/mL), a suspension of green algae (Ankistrodesmus falcatus; 4 x 107 cells/mL) and SelcoR (a commercial mixture of proteins and fatty acids, 0.6 mg/mL). During the exposure, the food was introduced at a rate of 0.5 mL of yeast suspension, 3.0 mL of algal suspension and 1.0 mL of SelcoR food supplement three times daily on weekdays and twice daily on weekends and holidays. At test termination, biological performance of the two control groups (solvent control and dilution water control) was statistically comparable and indicated that the presence of solvent (acetone; 24 µg/L) had no adverse effect on the survival, reproduction and growth of the test organisms during the study. Based on these analyses, all statistical comparisons of the biological end points at the various treatment levels were performed using pooled data from the solvent control and dilution water control groups. All daphnids exposed to the highest mean measured test concentration of Fenamiphos (0.49 µg a.i./L) died during the 21 days of exposure, which was significantly different (P < 0.05) from the survival of the pooled control organisms. The mean percent survival of daphnids exposed to the remaining treatment levels (0.24, 0.12, 0.066 and 0.032 µg a.i./L) ranged from 90 to 95 %. After 21 days of exposure, organism growth, determined as body length, was the most sensitive indicator of the toxicity in the concentration range  tested. Growth in the second highest treatment level (0.24 µg a.i./L) was determined to be 4.2 ± 0.1 mm. This was significantly different (P < 0.05) from the pooled control organisms (4.6 ± 0.3 mm). The mean body length in the remaining treatment levels (0.12, 0.066 and 0.032 µg a.i./L) was 4.5 mm which was statistically comparable to the body length of the pooled control daphnids. The 21-day no-observed-effect-concentrations for Daphnia magna were 0.24 and 0.12 µg a.i./L based on the number of offspring/female and the body lengths of parent animals. The lowest-observed-effect-concentrations were 0.49 and 0.24 mg a.i./L, respectively.

Description of key information

In a chronic flow-through test according to FIFRA; SLS protocol # 091087/DM-LC.FIF with Daphnia magna the lowest NOEC of the test item was determined as 0.12 µg a.i./L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

0.12 µg/L

Additional information

To determine the chronic effects of the test item on the survival, reproduction and growth of the daphnid (Daphnia magna) a study according to FIFRA; SLS protocol # 091087/DM-LC.FIF was carried out. The study was performed under continuous exposure, flowthrough conditions for a period of 21 days (one generation). Juvenile daphnids (<= 24 hours old, 40 daphnids per concentration) were exposed to nominal concentrations of 0.029, 0.058, 0.12, 0.23 and 0.47 µg a.i./L. The test item concentrations had been selected based on results of a range-finder study. Fortified well water according to the formula for hard water (ASTM, 1980) was used as dilution water and filtered through an Amberlite XAD-7 resin column in order to remove any potential organic contaminants.  The test item concentrations were analytically verified using a HPLC method and 14C screening scintillation measurements to be 0.032, 0.066, 0.12, 0.24, and 0.49 µg a.i./L (mean measured), i.e. to be 85.0 ± 7.17 % of nominal (mean value) throughout the test. The test solutions were supplied via a proportional diluter system with a flow rate of 6 aquarium volumes per 24-hour period in order to provide a 90% test solution replacement rate of approximately 9 hours. To prepare the stock solutions Acetone was used as vehicle. Test vessels were glass battery jars having a volume capacity of 1.8 L. Test solutions drained from the vessel through a 3.0 x 8.0 cm notch on the upper edge of the jars. The drains were covered with a NitexR 40-mesh screen to prevent loss of the daphnids. In addition to the five concentrations of the test item, dilution water control and solvent (acetone) control solutions were maintained during the study. The solvent control solutions contained the  greatest amount of acetone present in any treatment level (24 µg/L). All treatments and the controls were maintained in quadruplicate. The study was conducted in an air-temperature controlled room designed to maintain the test solution temperatures at 20 ± 1 °C. For additional temperature control the exposure vessels were partially submerged in a water bath maintained at the desired test temperature. Adult survival and  measurements of offspring production were made on days 1, 2, 4, and three times per week, (Monday, Wednesday and Friday), from day 7 through 21. The offspring were removed, counted and discarded. Test vessels were brushed to remove algal growth and the solution filtered through a fine mesh net a minimum of twice each week. At test termination the body length of all surviving daphnids in each treatment level and the controls was determined. Organism lengths were determined by measuring the daphnids from the top of the helmet to the base of the spine. The test organisms were fed a diet consisting of a suspension of Fleischmann1s yeast (5 mg/mL), a suspension of green algae (Ankistrodesmus falcatus; 4 x 107 cells/mL) and SelcoR (a commercial mixture of proteins and fatty acids, 0.6 mg/mL). During the exposure, the food was introduced at a rate of 0.5 mL of yeast suspension, 3.0 mL of algal suspension and 1.0 mL of SelcoR food supplement three times daily on weekdays and twice daily on weekends and holidays. At test termination, biological performance of the two control groups (solvent control and dilution water control) was statistically comparable and indicated that the presence of solvent (acetone; 24 µg/L) had no adverse effect on the survival, reproduction and growth of the test organisms during the study. Based on these analyses, all statistical comparisons of the biological end points at the various treatment levels were performed using pooled data from the solvent control and dilution water control groups. All daphnids exposed to the highest mean measured test concentration of Fenamiphos (0.49 µg a.i./L) died during the 21 days of exposure, which was significantly different (P < 0.05) from the survival of the pooled control organisms. The mean percent survival of daphnids exposed to the remaining treatment levels (0.24, 0.12, 0.066 and 0.032 µg a.i./L) ranged from 90 to 95 %. After 21 days of exposure, organism growth, determined as body length, was the most sensitive indicator of the toxicity in the concentration range  tested. Growth in the second highest treatment level (0.24 µg a.i./L) was determined to be 4.2 ± 0.1 mm. This was significantly different (P < 0.05) from the pooled control organisms (4.6 ± 0.3 mm). The mean body length in the remaining treatment levels (0.12, 0.066 and 0.032 µg a.i./L) was 4.5 mm which was statistically comparable to the body length of the pooled control daphnids. The 21-day no-observed-effect-concentrations for Daphnia magna were 0.24 and 0.12 µg a.i./L based on the number of offspring/female and the body lengths of parent animals. The lowest-observed-effect-concentrations were 0.49 and 0.24 mg a.i./L, respectively.