3,5-xylidine

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:

1997-12-24 - 1998-03-31

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study on behalf of competent authorities of Japan

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

1997

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

A stock solution with a concentration of 1000 mg/kg of the test substance was prepared. Each test solution was prepared in a 1.0L volumetric female flask by adding dilution water to the flask and then adding the stock solution of the test substance described above according to each concentration. The test solution was dispensed in 10 test containers of 80mL per concentration zone.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Age at study initiation (mean and range, SD): juvenile daphnia within 24 hours of birth
- Stage and instar at study initiation: juveniles
- Source: National Institute for Environmental Studies on July 18, 1995.
- Breeding density: Juveniles: 35 or 40 / 3L; Adults 35 / 3L
- Feeding
- Food type: Chlorella vulgaris
- Amount: 0.15 mg C per Daphnia magna/day




METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES, INCLUDING CULTURING CONDITIONS:
Adult females of sufficient size to be visually healthy with juvenile Daphnia magna were selected from those in the passages and transferred to a separately prepared beaker.
The next day, the produced larvae were divided into another beaker. The next day, the produced juveniles were divided into another beaker.
At the beginning of the fourth week, on the day before the start of exposure, the larvae were removed at least twice a week.
On the day before the start of the fourth week of exposure, adult females with juveniles in the broodstock were selected from batches that had not produced dormant eggs or males and had less than 5% mortality in the previous two weeks.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

63 mg/L 8CaCO3 equivalent)

Test temperature:

20±1 ℃

pH:

8.1

Nominal and measured concentrations:

control, 0.01, 0.03, 0.1, 0.3 and 1 mg/L (ratio 3.2)

Details on test conditions:

TEST SYSTEM
- Test vessel: beaker;
- Type (delete if not applicable): closed, Teflon sheet lid
- Material, size, headspace, fill volume: glass, 80 mL
- Daphnids: Adult females with juveniles in the broodstock were selected the day before the start of exposure, and juveniles produced the next day (within 24 hours) were used for the test (February 18, 1998).
- Renewal rate of test solution (frequency/flow rate): 3 times a week
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Dechlorinated water (Yokohama City tap water treated with activated carbon to remove residual chlorine, etc.)

OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod: 16h light/8h dark
- Light intensity: 1200lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
(parent Daphnia magna) Daily observations were made and recorded for live/dead, swimming condition, and any abnormalities in appearance.
Counting of produced larvae (survived) from first brood. The presence or absence of dead larvae, aborted eggs, or dormant eggs was observed and recorded daily. Water temperature, dissolved oxygen concentration (D.O.), pH, and hardness were measured four times during the exposure period, before and after water changes.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Range finding study
Based on the results of a 48-hour acute swimming inhibition test on Daphnia magna (48 hr-EC50 value: 2.20 mg/L), the following five levels were set in this test.

Reference substance (positive control):

yes

Remarks:

potassium dichromate The EiC50 was 0.23 mg/kg for 48 hours.

Duration:

21 d

Dose descriptor:

LC50

Effect conc.:

0.167 mg/L

95% CI:

0.087 - <= 0.357

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

0.138 mg/L

95% CI:

0.106 - <= 0.229

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

immobilisation

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.03 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

immobilisation

Details on results:

The concentrations of the test substance in the test solution measured during the exposure period were within ±20% of the set value.

No dormant eggs were observed in the control and all concentrations throughout the entire exposure period.

Reported statistics and error estimates:

Using the number of Daphnia magna deaths in each concentration zone and the number of Daphnia magna tested (10), the Binomial method, the Moving average method, or the Probit method, as appropriate, was used to calculate the 21-day half-lethal concentration (LC50). The 50% reproductive inhibition concentration (EC50) was calculated by the Logit method.
The highest concentration at which no significant differences were found was the maximum no effect concentration (NOEC), and the lowest concentration at which significant differences were found was the minimum effect concentration (LOEC). Statistical methods: Bartlett's test of equal variance, one-way ANOVA, Dunnett or Williams multiple comparison test (α = 0.05, two-tailed).

Validity criteria fulfilled:

yes

Conclusions:

The median immobilisation concentration (EC50) after 21 days was determined to be 0.138 mg/L, the median lethal concentration (LC50) after 21 days was 0.167 mg/L, and the NOEC was determined to be 0.03 mg/L.

Executive summary:

A GLP-  reproduction test (semi-static) of 3,5-xylidine on Daphnia magna in a 21-days exposure was carried out in accordance with the Daphnia magna reproduction test described in "Methods of Tests pertaining to New chemical Substances, Etc" and comparable to OECD Guideline 211.

10 daphnids per concentration area (1 daphnid/ container) were exposed to the test substance at semi-static conditions and at test concentrations of  0.01, 0.03, 0.1, 0.3 and 1 mg/L (nominal) and control. The median immobilisation concentration (EC50) after 21 days was determined to be 0.138 mg/L, the median lethal concentration (LC50) after 21 days was 0.167 mg/L, and the NOEC was determined to be 0.03 mg/L.

Description of key information

OECD 211, GLP, Daphnia magna, semi-static: EC50(21d) 0.138 mg/L, LC50(21d) 0.167 mg/L, NOEC 0.03 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

0.03 mg/L