Diethyl (hydroxymethyl)phosphonate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

For the test group (100 mg/L), six Daphnia were added to one replicate vessel instead of 5. The addition of an extra daphnid had no impact on either the validity or integrity of the study.

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

yes

Remarks:

see above

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The test concentration of E06-16 was measured using liquid chromatography with Mass Spectrometric detection (LC-MS). At the start of the definitive test, four samples (10 mL) were taken from the freshly-prepared control and test media. After 48 ours, the contents of the test vessels from the control and test group were pooled and further samples were taken for analysis. On each occasion, two of the samples was analysed and the other was stored in a freezer in case further analysis was required.

Vehicle:

no

Details on test solutions:

The method of preparation used during the definitive test was based on the results of a formulation trial and a range finding test.
The test substance (100 mg) was added to dilution medium (ca. 700 mL) in a volumetric flask (1 L), made up to volume and vigorously mixed to provide test medium with a nominal concentration of 100 mg/L as E06-16.

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna (Straus) were cultured in-house and were obtained from a strain originating from the National Institute for Applied Chemical Research (IRCHA), France. Cultures were fed daily with a suspension of the unicellular green algae, Pseudokirchneriella subcapitata, to provide nominally 0.1 to 0.2 mg carbon per daphnid, per day, except during the initial two days when a slightly lower ration was given. Culture conditions ensure that the stock animals reproduce by parthenogenesis.
The day before the start of the study, all juvenile Daphnia were removed from the laboratory cultures. The following morning, juveniles produced by the gravid (egg-bearing) adult Daphnia were removed from the culture vessels and held in a separate holding vessel; these animals, which were less than 24 hours old, were used in the test.

Test type:

static

Water media type:

other: Elendt M4 medium

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

The range finding test employed nominal test concentrations of 0.1, 1, 10 and 100 mg/L as E06-16. After 48 hours, there was no observed immobilisation in any of the test groups. Based on this result, the definitive test employed a single nominal concentration (limit test) of
100 mg/L as E06-16.

Hardness:

The total hardness and alkalinity of the batch of Elendt M4 medium used were 253 and 48 mg/L as CaCO3,
respectively

Test temperature:

Control: 21.0 - 22.0 °C
Treatment: 21.1 - 22.2 °C

pH:

Control: 8.01 - 8.18
Treatment: 8.22 - 8.23

Dissolved oxygen:

around 9 mg/L

Nominal and measured concentrations:

100 and 112 mg/L respectively

Details on test conditions:

Twenty Daphnia, four replicates of five animals per vessel, were exposed in each control and test group. Daphnia were exposed to the test or control conditions for a period of 48 hours without renewal of test medium. During the definitive test, continuous monitoring of the medium in an additional vessel indicated that temperatures ranged between 21.3 to 22.4°C. A photoperiod of 16 hours light : 8 hours dark was maintained. No supplementary aeration was employed and no feed was given during the exposure period.

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

other: EC50 and NOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

other: EC50 and NOEC

Effect conc.:

> 112 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

The intended exposure concentration of E06-16 was adequately achieved (with replicate samples ranging between 106% and 116% of its nominal value) and maintained during the test (108% of its starting value). The overall mean measured concentration of E06-16 was 112 mg/L and this value has been used in the determination of study end-points. There was no immobilisation observed during the test, giving a 48 hour EC50 of greater than 112 mg/L, and a NOEC (no observed effect concentration) of 112 mg/L (measured).

Results with reference substance (positive control):

n/a

Reported statistics and error estimates:

The intended exposure concentration of E06-16 was adequately achieved (with replicate samples ranging between 106% and 116% of its nominal value) and maintained during the test (108% of its starting value). The overall mean measured concentration of E06-16 was 112 mg/L and this value has been used in the determination of study end-points.

Validity criteria fulfilled:

yes

Conclusions:

In the acute toxicity of E06-16 to Daphnia magna the test substance was found to be not acutely toxic at a mean measured concentration of 112 mg/L.

Executive summary:

The acute toxicity of E06-16 to Daphnia magna was assessed under static exposure conditions over a period of 48 hours. E06-16 was not found to be acutely toxic to Daphnia magna at a mean measured concentration of 112 mg/L.

Based on these findings, the 48-hour EC50 for immobilisation could not be calculated but must be greater than 112 mg/L (measured) and the no-observed-effect concentration (NOEC) was 112 mg/L (measured).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

112 mg/L