1,4-dimethoxybenzene

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to fish, other

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The test conditions, even if not in accordance with the recognised EC and OECD test guidelines, are sufficiently described to be validated. The GLP are not mentioned.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The study was conducted to determine the sublethal effect of chemicals for an extended period (approx. 32d) on embryonic development, survival and growth of juvenile fish.

GLP compliance:

not specified

Analytical monitoring:

yes

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
No data

Test organisms (species):

Pimephales promelas

Details on test organisms:

TEST ORGANISM
- Common name: Fathead minnow
- Strain: Pimephales promelas
- Source: no data
- Pre-exposure reproductive performance: not applicable


METHOD FOR PREPARATION AND COLLECTION OF FERTILIZED EGGS
- Numbers of parental fish (i.e. of females used to provide required number of eggs): no data
- Method of collection of fertilised eggs: no data
- Subsequent handling of eggs: fertilized eggs less than 24H old were incubated in glass-sided eggs cup with nylonscreen bottoms. Two egg cups were suspended in each aquarium. 30 eggs per cup were added in all tests. By a motor assembly, the eggs cup were slowly moved up and down in the water column a distance of approx. 5 cm. Upon completion of hatch (4-5 d), surviving fry were counted and 30 fry were released from the incubation cups into each aquarium.


POST-HATCH FEEDING
- Start date: 4-5 d
- Type/source of feed: Artemia and Tetramin
- Amount given: in equal volumes to each chamber (no more data)
- Frequency of feeding:fish were fed from the day after hatching to the end of each test (31-33 d)

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

33 d

Post exposure observation period:

no data

Hardness:

45.2 (+/-2.0)

Test temperature:

24.4 to 25.7°C (mean temperatures for the seven tested compounds)

pH:

7.7 (+/-0.2)

Dissolved oxygen:

65.2 to 78.6% of saturation (mean temperatures for the seven tested compounds)

Nominal and measured concentrations:

Measured concentrations : 7.16 (+/-1.27), 16.6 (+/-2.2), 27.4 (+/-2.94), 39.2 (+/-3.85), 60.4 (+/-5.6) mg/L.

Details on test conditions:

TEST SYSTEM
- Emybro cups (if used, type/material, size, fill volume): glass-sided eggs cup with nylon screen bottoms. Two egg cups were suspended in each aquarium.
- Test vessel:
- Type (delete if not applicable): open / closed: open
- Material, size, headspace, fill volume: 17.5 -L glass aquaria (20x35x25 cm), containing 4.5 to 4.9 liters of water
- Aeration: no data
- Type of flow-through (e.g. peristaltic or proportional diluter): water was delivered through one of two proportional diluter systems
- Renewal rate of test solution (frequency/flow rate): the diluter delivered 0.5 liters of water plus toxicant to each exposure chamber every 17.4 to 26.6 min.
- No. of fertilized eggs/embryos per vessel: 30
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): none
- Biomass loading rate: no data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Lake Superior water
- Alkalinity: 43.7 +/- 1.2, no other data
- Culture medium different from test medium: no
- Intervals of water quality measurement:no data

OTHER TEST CONDITIONS
- Adjustment of pH: no data
- Photoperiod: 16H light/8H dark
- Light intensity: artificial lighting was provided by fluorescent bulbs and intensities of 28+/-6 and 34+/- 7 ft-c at the water surfaces of the individual aquaria were measured.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Percent hatch, percent abnormal plus dead fry immediately after hatch, percent survival of transferred fry throughout the exposure period and length and weight of juvenile fish at the end of each exposure

VEHICLE CONTROL PERFORMED:no

RANGE-FINDING STUDY no data

Reference substance (positive control):

not specified

Duration:

33 d

Dose descriptor:

NOEC

Effect conc.:

16.6 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: Hatchability, larval development, survival or growth in Fathead minnows.

Duration:

33 d

Dose descriptor:

LOEC

Effect conc.:

27.4 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: significant reduction in wet weight and standard length

Duration:

33 d

Dose descriptor:

other: MATC

Effect conc.:

21.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

other: Hatchability, larval development, survival or growth in Fathead minnows.

Details on results:

MATC: estimated maximum acceptable toxicant concentration determined as the geometric mean of NOEC ad LOEC.

Both wet weight and standard length were the most sensitive parameters with identical levels significance.
The percentage of newly hatched fry died or were malformed (percent dead plus abnormal) was affected at the two highest exposures (39.2 and 60.4 mg/L) of PDMB.
Fish survival was significantly reduced at the highest exposure (60.4 mg/L) of PDMB.
Whereas embryo hatchability was not different from controls.

Results with reference substance (positive control):

no data

Reported statistics and error estimates:

Data were analysed by one-way analysis of variance in conjunction with Dunnett's procedure.

Validity criteria fulfilled:

not specified

Executive summary:

In a subchronic toxicity study, eggs and subsequent hatched fries of Pimephales promelas were exposed to Paradimethoxybenzene at doses from 0 to 60.4 mg/L in flow-through system during approximately 33 days.

A NOEC based on the hatchability, larval development, survival or growth in Pimephales promelas was determined to 16.6 mg/L .

A LOEC based on wet weight and standard length was determined to 27.4 mg/L.

Description of key information

Eggs of Pimephales promelas were exposed to Paradimethoxybenzene at doses from 0 to 60.4 mg/L.
The NOEC-33d was 16.6 mg/L based on the hatchability, larval development, survival or growth in Pimephales promelas.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

16.6 mg/L

Additional information

Only one study (Call et al., 1985) was available and was selected as key study.