Chlorpyrifos

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: OECD guideline 202

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Substance ID: Dursban F TG001 Technical
Batch#: EK 880303344
Purity: Contains 97.2% of chlorpyrifos

Analytical monitoring:

yes

Details on sampling:

At the start of the test (just after dosing) about 1 litre samples were taken from the solvent control and the test solutions containing 0.1, 0.18 and 0.32 µg of test substance per liter (nominal) and at t = 9 d, just after dosing, 1-2 litre samples, from the solvent control and the test solutions containing 0.018, 0.032, 0.056 and 0.1 µg/L(nominal).
At t = 2 days (samples after 48 hours) 0.5-1 litre samples were taken from the solvent control and the spent test solutions containing 0.10 and 0.32 µg of test substance (nominal) per litre, and at t = 12 days (samples after 72 hours), 1-1.5 litre samples, from the test solutions containing 0.056 and 0.1 µg/L (nominal).

Vehicle:

yes

Remarks:

Dilution water prepared from ground water

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
100 ± 0.1 mg of test substance was accurately weighed out and dissolved in 100 ml of dimethyl sulphoxide (DMSO). From this solution 100 µL was diluted to 10 ml, with DMSO, to prepare a solution containing 10 mg/L. From this solution 0.18, 0.32, 0.56, 1.0, 1.8 and 3.2 ml were diluted to 10 ml with DMSO. In this way concentrated solutions of test substance containing 0.18, 0.32, 0.56, 1.0, 1.8 and 3.2 mgl were prepared. These stock solutions were prepared freshly once per week and stored in the dark in a refrigerator. From each of these concentrated solutions 0.2 ml was mixed with 2 litre of dilution water. These solutions, containing nominal 0.018, 0.032, 0.056, 0.10, 0.18 and 0.32 µg of test substance per litre respectively were used as test solutions; portions of 400 ml of each test solution were placed in each of four 600 ml beakers.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Age of parental stock: Less than 24 h old
- Feeding during test: During the test the animals were fed with cells of the unicellar alga Chlorella pyrenoidosa and some 'sludge extract' was added as food additive (yielding a COD of 0.5 mg/L).
- Amount: 625 µL of sludge extract was added to each test vessel.

Test type:

static

Water media type:

other:

Total exposure duration:

21 d

Hardness:

210 mg/L as CacO3

Test temperature:

20 ± 1°C

pH:

7.7 - 8.8

Dissolved oxygen:

>7.5 mg/L

Nominal and measured concentrations:

Nominal: 0.018, 0.032, 0.056, 0.10, 0.18 and 0.32 µg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 600 ml glass beakers each containing 400 ml of test solution
- Aeration: Test system was aerated and during the test the animals were fed with cells of the unicellar alga Chlorella pyrenoidosa and some 'sludge extract' was added as food additive (yielding a COD of 0.5 mg.l-1).
- No. of organisms per vessel: 10 daphnids
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates): 4


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Synthetic medium is prepared by addition of several salts to groundwater from a locality near Linschoten (the Netherlands).
- Particulate matter: The groundwater contains several other trace elements (<1 mg/L).
- Hardness: 215 mg/L as CaCO3
- Culture medium different from test medium: No

OTHER TEST CONDITIONS
- Adjustment of pH: The equilibrium pH of the medium, after aeration, should be 8.3 - 8.5, but usually is slightly less, namely 8.0 - 8.2.
- Photoperiod: 16 h light - 8 h dark

EFFECT PARAMETERS MEASURED : At each replacement time the dead animals and young born were counted and removed; the condition and the size of the original test animals were qualitatively compared with those of the control animals. LC50, EC50, NOEC and LOEC values are determined bawsed on mortality, reproduction, size, growth, colour and swimming behaviour.

Key result

Duration:

21 d

Dose descriptor:

LC50

Effect conc.:

0.06 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

> 0.056 - < 0.1 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.056 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Mortality, reproduction, colour, size and swimming behaviour

Key result

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

0.081 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

12 d

Dose descriptor:

LC50

Effect conc.:

0.092 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

9 d

Dose descriptor:

LC50

Effect conc.:

0.12 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

7 d

Dose descriptor:

LC50

Effect conc.:

0.15 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

5 d

Dose descriptor:

LC50

Effect conc.:

0.2 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

2 d

Dose descriptor:

LC50

Effect conc.:

> 0.32 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

- Behavioural abnormalities: At 0.056 µg/L and the lower concentrations tested showed no effects on colour and swimming behaiour which were visually estimated.
- Observations on body length and weight: At 0.056 µg/L and the lower concentrations tested showed no effects on size.
- Other biological observations: No significant (binomial test; p = 0.95) effects on mortality were found at 0.056 µg/L and the lower concentrations tested. At 0.10 µg/L, all animals died within 14 days of exposure. No reproduction reduction was found at 0.056 µg/L and the lower concentrations tested. An almost complete reproduction reduction was found at 0.10 µg/L.
- Mortality of control: Mortality was observed in control animals in negative control and solvent control. At day 21, 8 animals died in negative control and 6 animals died in solvent control and the control mortality was ≤20%, in accordance with that allowed in the guideline.
- Any observations that might cause a difference between measured and nominal values: At the start of the test and after nine days the actual ('average') concentrations of active ingredient in the clean test solutions (just after dosing) were 86% of the nominal concentrations of active ingredient dosed. After two and twelve days (tests for stability) the actual ('average') concentration of active ingredient in the 'spent' test solutions were 71% of the dosed amounts and 56% of the nominal concentrations of active ingredient. As far as could be estimated from the chemical analyses carried out, the 'average' concentration of active ingredient during the test was 71% of the nominal concentration of active ingredient.

Reported statistics and error estimates:

Statistical significance for mortality was determined with a binomial test with a 95% significance level combining the results of the quadruplicates. Statistical significance for reproduction was determined with the one tailed Student t-test with a 95% significance level using the mean number of young per female in each of the four replicates as observed values. In both cases the observations at each concentration were compared with those of the solvent control.

Conclusions:

21-Day NOEC (Daphnia magna): 0.056 µg/L (Based on mortality and reproduction)
21-Day LOEC (Daphnia magna): 0.10 µg.L

Executive summary:

The study was conducted according to guideline OECD 202 to evaluate the influence of test substance on reproduction and mortality of the fresh-water crustacean Daphnia magna. The exposure period was 21-days. The concentrations of test substance tested were 0.018, 0.032, 0.056, 0.10, 0.18 and 0.32 µg/L.

The 21 d LC50 was calculated from the data to be 0.060 µg/L (no confidence interval could be calculated because the number of concentrations with partial mortality was too low). At 0.10, 0.18 and 0.32 µg/L, all animals died within the 21 days of exposure. No significant effect (binomial test; p = 0.95) on mortality of Daphnia magna was found at 0.056 µg/L and the lower concentrations tested.

The 21 d EC50 (E = reproduction) was estimated from the data to be >0.056 µg/L and <0.10 µg/L. No reproduction reduction was found at the concentration of 0.056 µg/L and the lower concentrations tested.

THE 21-day NOEC of test substance based on mortality and reproduction was 0.056 µg/L and the LOEC was 0.10 µg/L.

In addition to the quantitatively determined effects on mortality and reproduction, effects on size, color and swimming behaviour were visually estimated. At 0.056 µg/L and the lower concentrations tested no effects on these criteria, which are somewhat subjective, were found.

Description of key information

Freshwater

21-day EC50 (Daphnia magna): 0.056 µg/L (Based on mortality and reproduction); OECD 202; Reliability = 2

Saltwater

35 -day NOEC (Mysid): 4.6 ng/L (Based on survival and growth); EPA 72 -4, ASTM E 1191 -87, Reliability = 1

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.056 µg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

4.6 ng/L

Additional information

The LC50 value from the 21-d chronic aquatic invertebrate toxicity test in Daphnia magna was 0.056 µg/L for immobility and reproduction.

One chronic saltwater invertebrate toxicity test was conducted. The chronic NOEC value in mysid in a 35 day study was 4.6 ng/L.