long chain alkyl thio carbamide metal complex

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:

05-Nov-2003 to 22-Dec-2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Deviations:

yes

Remarks:

(mortality 30% in control group)

Qualifier:

according to guideline

Guideline:

other: OECD Series on Testing and Assessment. No. 23. Guidance document on aquatic toxicity testing of difficult substances and mixtures

Deviations:

no

Principles of method if other than guideline:

As the coefficient of variance for juvenile production in the control group was low, the mortality in the test groups did not exceed 20% at any level and, in the absence of any statistically significant effects on either parental growth or reproduction, the validity of the study was not thought to have been affected by the death of an additional parental control animal.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Remarks:

Total Organic Carbon (TOC) analysis

Details on sampling:

- Concentrations: Nominally 0, 0.954, 3.05, 9.77, 31.3 and 100 mg/litre
- Sampling method: Total Organic Carbon (TOC) analysis was employed to measure TOC values in the test media in comparison to control values to determine if any of the test material was in solution. The exposure concentrations of the test material itself were not quantified. Two samples (ca. 100 ml) were taken from the freshly-prepared control and test media on Days 0, 7, 14 and 18; samples of expired media were collected from the pooled contents of the replicate control and test vessels on Days 9, 16 and 21.
- Sample storage conditions before analysis: Samples were either analysed immediately or stored frozen until required for analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: test solutions were prepared as water accommodated fractions (WAFs) at a loading rate of up to 100 mg/litre. On each occasion, the test material (6.1, 19.5, 62.6 and 200 mg) was weighed onto Teflon® discs, which were placed directly into Elendt M4 medium (800 ml) contained in glass bottles before being made up to volume (2 litres) with culture medium. The vessels were covered to exclude light and their contents were stirred for approximately 40 hours at a rate capable of generating a vortex of approximately 10% of the static depth of the medium. On cessation of stirring, the media were left to stand for approximately 4 hours. An aliquot (ca. 100 ml) was withdrawn from each vessel via a sampling tube positioned mid-vessel and discarded. The required volume of medium (Water Accommodated Fraction; WAF) was then siphoned from each vessel; the remaining WAFs were then used as the test media. An aliquot of the WAF removed from the medium prepared at a nominal loading rate of 3.05 mg/litre was diluted with Elendt M4 medium to provide medium at the lowest test concentration (0.954 mg/litre). The temperature of the test media was monitored during preparation; it was maintained below 25 ºC.

- Controls: yes, Elendt M4 culture medium alone
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Elendt M4 medium
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc): on the days of preparation, the aqueous mixtures of the test material were non-homogenous dispersions with the test material remaining on the Teflon® discs. The WAFs were clear and colourless.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain/clone: Straus
- Justification for species other than prescribed by test guideline: as guideline
- Source: Institute National de Recherché Chimique Appliqué (IRChA), France
- Age of parental stock (mean and range, SD): neonates (<24 hours old)
- Feeding during test: yes
- Food type: a concentrated suspension of Chlorella vulgaris
- Amount: ~0.1-0.15 mg carbon/Daphnia per day, except for the first 2 days when 0.07 mg carbon/vessel per day
- Frequency: daily

ACCLIMATION
- not applicable (neonates used for study)

QUARANTINE (wild caught)
- not applicable

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:
- at medium renewal (i.e. on days 2, 4, 7, 9, 11, 14, 16 and 18), any dead animals were discarded and the surviving parental Daphnia (mobile and immobile) were transferred to fresh control and test media in a second set of vessels. Any neonates, unhatched eggs or carapaces present in the expired media were counted and then discarded. On the days between renewals, the vessels were checked for neonates and carapaces and where neonates were present, these were removed from the vessel using a pipette and counted.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

none

Hardness:

242-266 mg CaCO3/litre
The protocol stated that the hardness of the dilution medium should remain within the range 200 to 250 mg/l as CaCO3. However, the hardness of the media used in the study ranged from 242 to 266 mg/l as CaCO3. As no effects were observed on the Daphnia, the integrity of the study is not thought to have been affected.

Test temperature:

19.9-21.1 ºC

pH:

7.47-8.05

Dissolved oxygen:

90-104 mg/litre

Salinity:

not applicable

Nominal and measured concentrations:

Nominal: 0, 0.954, 3.05, 9.77, 31.3 and 100 mg/litre
Exposure concentrations of the test material itself were not quantified. Mean Total Organic Carbon (TOC) in the test media: 1.4, 1.4, 1.5, 1.4, 1.7 and 1.5 mg/litre

Details on test conditions:

TEST SYSTEM
- Test vessel: glass jar
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: glass, 60 ml capacity, presumably 60 ml volumes of test media
- Aeration: no supplementary aeration was employed
- Type of flow-through (e.g. peristaltic or proportional diluter): not applicable
- Renewal rate of test solution (frequency/flow rate): test media were renewed on days 2, 4, 7, 9, 11, 14, 16 and 18
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10
- No. of vessels per vehicle control (replicates): not applicable
- Biomass loading rate: presumably 60 ml/daphnid

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:Elendt M4 medium
- Total organic carbon: 0.8-0.9 mg C/litre
- Particulate matter: not applicable
- Metals: not applicable
- Pesticides: not applicable
- Chlorine: not applicable
- Alkalinity: 48-70 mg CaCO3/litre
- Ca/mg ratio: not applicable
- Conductivity: not applicable
- Salinity: not applicable
- Culture medium different from test medium: no
- Intervals of water quality measurement: not applicable

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours light, 8 hours dark
- Light intensity: "subdued"

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : the numbers of mobile, immobile, dead and gravid (animals with eggs in the brood pouch) parental Daphnia were recorded daily, together with any general observations of their size and appearance if different from the controls. From Day 9 (the first occasion when juveniles were observed), the numbers of live and dead neonates and the presence of unhatched eggs in each vessel were recorded daily. The number of moults produced by the parental generation was also recorded throughout the test.

VEHICLE CONTROL PERFORMED: no (no vehicle employed)

RANGE-FINDING STUDY
- Test concentrations: nominally 1, 5, 10, 50 and 100 mg/litre
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

EL50

Remarks:

water accommodated fraction tested; concentration expressed as loading rate

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Key result

Duration:

21 d

Dose descriptor:

NOELR

Remarks:

water accommodated fraction tested; concentration expressed as loading rate

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

For the 0, 0.954, 3.05, 9.77, 31.3, 100 mg/litre groups respectively:
- Mortality of parent animals: 3, 1, 0, 0, 2, 1
- No. of offspring produced per day per female: not applicable
- Body length and weight of parent animals: mean for surviving animals, 3.9, 3.9, 4.0, 3.9, 3.9, 3.9
- Type and number of morphological abnormalities: not applicable
- Type and number of behavioural abnormalities: not applicable
- Number of males and females (parental): not applicable
- Time to first brood release or time to hatch: day 9
- Egg development time: not applicable
- Brood size:
- mean neonate production (live), 83.0, 85.9, 84.4, 79.1, 80.5, 85.2
- Time to sexual maturity: not applicable
- Type and magnitude of biochemical changes: not applicable
- Other biological observations: mean number of moults, 8.0, 8.2, 8.3, 7.8, 8.3, 8.7
- Effect concentrations exceeding solubility of substance in test medium: no data

Results with reference substance (positive control):

not applicable

Reported statistics and error estimates:

Body length, total number of live neonates produced by each surviving adult by day 21: no statistically significant differences
Coefficient of variation for fecundity in the control group after 21 days: 13%

Mortality of the parental animals in the control group (30%) exceeded the guideline level (20%). However, mortality in the test groups did not exceed 20% and there were no statistically significant effects on either parental growth or reproduction. The validity of the study was not thought to have been compromised by the death of an additional parental control animal.

Validity criteria fulfilled:

no

Remarks:

Although the parental mortality in the control group was 30%, the validity of the study was not thought to have been affected by the death of an additional parental control animal.

Conclusions:

In a GLP study conducted according to OECD guideline 211 (and OECD guidance document 23), no significant effects on reproduction, survival, body length or number of moults were seen in Daphnia magna exposed to nominal concentrations of EC#457-320-2 of up to 100 mg/litre for 21 days under semi-static conditions. Effect concentrations were based on loading rates as there were no data on the measured mass of test material in the WAFs.

Executive summary:

In a GLP study conducted according to OECD guideline 211 and OECD guidance document 23, Daphnia magna were exposed to nominal concentrations of EC# 457-320-2 of 0, 0.954, 3.05, 9.77, 31.3 and 100 mg/litre for 21 days under semi-static conditions. The test material was poorly soluble in water and its toxicity was determined by preparing water-accommodated fractions (WAFs). Test mixtures were prepared by placing the appropriate amount of test material onto Teflon discs and placing in glass bottles with 2 litres Elendt M4 culture medium. After stirring for 40 h and allowing to settle for 4 h, the WAFs were siphoned from each vessel. Concentrations of the test material itself were not quantified but total organic carbon (TOC) analysis was employed. Groups of 10 Daphnia/concentration were exposed to each WAF for 21 days, with media renewed every 2-3 days and a further group was exposed to culture medium alone. Daphnids were fed algae daily. Test and control groups were evaluated for immobilisation, mortality, reproduction, number of moults and body length.

No 21-day EL50 could be determined since there were no statistically significant differences in any of the endpoints measured at any concentration. The NOELR was 100 mg/litre (nominal), the highest loading rate tested. TOC concentrations were similar in all test mixtures and the control (1.4-1.7 mg/litre).

In conclusion, no significant effects on reproduction, survival, body length or number of moults were seen in Daphnia magna exposed to nominal concentrations of EC# 457-320-2 of up to 100 mg/litre for 21 days. Effect concentrations were based on loading rates as there were no data on the measured mass of test material in the WAFs.

Description of key information

The NOELR in a 21-day Daphnia reproduction study was 100 mg/L (nominal loading rate).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L

Additional information

One long-term toxicity to aquatic invertebrates study is available: a 21-day Daphnia reproduction study, conducted in accordance with GLP and OECD Test Guideline 211. Due to the poor water solubility of the test substance, test waters were prepared as water accommodated fractions (WAFs) of the test substance at nominal loading rates of 0, 0.954, 3.05, 9.77, 31.3 and 100 mg/litre. Concentrations of the test material itself were not quantified but total organic carbon (TOC) analysis was employed.

No 21-day EL50 could be determined since there were no statistically significant differences in any of the endpoints measured at any concentration. The NOELR was 100 mg/litre (nominal), the highest loading rate tested. TOC concentrations were similar in all test mixtures and the control (1.4-1.7 mg/litre).