Diethyl (hydroxymethyl)phosphonate

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:

February - March 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

n/a

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1300 (Daphnid Chronic Toxicity Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Lot number 540-1013-14.

Analytical monitoring:

yes

Details on sampling:

Samples were collected from each treatment and control group one day prior to the start of the test after conditioning the diluter for one day. 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, and processed immediately for analysis.

Vehicle:

no

Details on test solutions:

The test substance used to prepare the test solutions, analytical calibration standards and the analytical matrix fortification samples for the study was received from ICL Industrial Products. Individual stock solutions were prepared for each of the five concentrations tested, and were prepared seven times during the study. Test solution concentrations were not adjusted for the active ingredient of the test substance during preparation, and are based on the test substance as received. A primary stock solution was prepared by mixing a calculated amount of test substance into reverse osmosis (RO) water at a nominal concentration of 120 mg/mL.

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnid neonates used in the test were less than 24 hours old and were obtained from cultures maintained by Wildlife International, Easton,
Maryland. Adult daphnids were cultured in water from the same source and at approximately the same temperature as used during the test. The pH of the water ranged from 8.1 to 8.4, measured with a Thermo Orion Benchtop
4 Star Plus pH meter. Dissolved oxygen concentrations were 7.8 mg/L (87% of saturation),
measured with a Thermo Orion Benchtop 3 Star Plus dissolved oxygen meter.

Test type:

flow-through

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

21 d

Remarks on exposure duration:

not relevant

Post exposure observation period:

not relevant

Hardness:

140 – 148 mg/L as CaCO3

Test temperature:

20 ± 1°C

pH:

7.8 - 8.2

Dissolved oxygen:

≥ 81% of saturation (7.3 mg/L).

Salinity:

Alkalinity 174 – 176 mg/L as CaCO3

Conductivity:

350 uS/cm

Nominal and measured concentrations:

Nominal concentrations: 7.5 mg/L, 15 mg/L, 30 mg/L, 60 mg/L, 120 mg/L.
Measured concentrations: .5 mg/L, 15 mg/L, 29 mg/L, 59 mg/L, 119 mg/L.

Details on test conditions:

TEST SYSTEM
- Test chambers: 12-L glass aquaria filled with approximately 9 L of test water.
- Type of Flow-Through: A continuous-flow diluter used to deliver each concentration of the test substance and a negative control (dilution water) to test vessels. Syringe pumps (Harvard Apparatus, Holliston, Massachusetts) were used to deliver test substance stock solutions to impartially assigned mixing chambers.
-Achievement of desired test concentrations: The five test substance stock solutions were injected into the diluter mixing chambers at a rate of 50.0 μL/minute where they were mixed with dilution water delivered at a rate of 100 mL/minute. Negative control received dilution water only.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates):2
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: obtained from a well approximately 40 meters deep located on the Wildlife International site. Prior to use, the water was filtered to 0.45 um to remove fine particles and was passed through an ultraviolet (UV) sterilizer.
- Stock solutions were stored at ambient temperature in glass amber bottles with Teflon®-lined lids, and aliquots of each stock were placed on the syringe

OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod: 16 hours light, 8 hours dark
- Light intensity:333 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Survival, reproduction, growth

VEHICLE CONTROL PERFORMED: no

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

119 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: mortality & reproduction

Remarks on result:

other: Highest concentration tested

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

59 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth

Remarks on result:

other: most sensitive endpoint

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 119 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: mortality, growth & reproduction

Remarks on result:

other: highest concentration tested

Key result

Duration:

21 d

Dose descriptor:

EL50

Effect conc.:

> 119 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: mortality, growth & reproduction

Remarks on result:

other: highest concentration tested

Details on results:

Mortality of parent animals: 0% for all concentrations.
- No. of offspring produced per day per female: 15
- Body length and weight of parent animals: 5 mm and 1.31- 1.47 mg
- Type and number of morphological abnormalities: /
- Type and number of behavioural abnormalities:/
- Number of males and females (parental): /
- Time to first brood release or time to hatch: Day 7 or 8
- Brood size: Daphnids in the negative control group averaged 5.1 mm in length and 1.47 mg in dry weight. Daphnids in the 7.5,15, 29, 59 and 119 mg/L treatment groups had mean lengths of 5.1, 5.1, 5.1, 5.1 and 5.0 mm respectively, and mean dry weights of 1.45, 1.31, 1.35, 1.40 and 1.32 mg, respectively.

Reported statistics and error estimates:

Survival and Clinical Observations:
Fisher’s Exact test indicated that no statistically significant reductions in survival were noted in any of the E06-16 treatment groups in comparison to the negative control (p > 0.05).

Reproduction:
Dunnett’s test indicated there were no statistically significant decreases in mean neonate production per reproductive day in any of the treatment groups in comparison to the negative control (p > 0.05). According to the one-sided Jonckheere-Terpstra step-down trend test, there was no statistically significant, concentration related trend evident in mean neonate production per reproductive day when all of the data was included in the trend test calculations (p > 0.05).
Dunnett’s test indicated there were no statistically significant decreases in mean neonate production per parent animal alive at the beginning of the test in any of the treatment groups in comparison to the negative control (p > 0.05). According to the one-sided Jonckheere-Terpstra step-down trend test, there was no statistically significant, concentration related trend evident in mean neonate production per parent animal alive at the beginning of the test when all of the data was included in the trend test calculations (p > 0.05).

Growth:
Dunnett’s test indicated there was a statistically significant, concentration-related trend in the 119 mg/L treatment group in comparison to the negative control (p ≤ 0.05). According to the one-sided Jonckheere-Terpstra step-down trend test, a statistically significant, concentration-related trend was no longer evident
when the data from the 119 mg/L treatment group was excluded from the calculations (p ≤ 0.05).

Validity criteria fulfilled:

yes

Conclusions:

There were no statistically significant treatment-related effects on survival, reproduction or growth at concentrations ≤ 59 mg/L. Growth, measured as length and dry weight, was the most sensitive biological endpoint measured in this study. Daphnids exposed to E06-16 at concentrations ≥119 mg/L had statistically significant reductions in length and weight in comparison to the negative control. Consequently, the NOEC, based on growth, was 59 mg/L. The LOEC was 119 mg/L and the MATC was calculated to be 84 mg/L. The 21-day EC50 value for adult immobility was > 119 mg/L, the highest concentration tested, and the 21-day
EC10 and EC50 values for reproduction was > 119 mg/L.

Executive summary:

The effect of E06 -16 on the survival, growth and reproduction of the cladoceran, Daphnia magna, was determined during a 21-day exposure period under flow-through test conditions.

Daphnids were exposed to a geometric series of five test concentrations (7.5 to 119 mg/L) and a negative control (dilution water).

There were no statistically significant treatment-related effects on survival, reproduction or growth at concentrations ≤ 59 mg/L. However, growth, measured as length and dry weight, was the most sensitive biological endpoint. Daphnids exposed to E06-16 at concentrations ≥119 mg/L had statistically significant reductions in length and weight in comparison to the negative control. Consequently, the NOEC, based on growth, was determined to be 59 mg/L, the LOEC 119 mg/L and the MATC was calculated to be 84 mg/L. The 21-day EC50 value for adult immobility was determined to be > 119 mg/L, the highest concentration tested, and the 21-day EC10 and EC50 values for reproduction were > 119 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

59 mg/L