Magnesium ethanolate

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adult fish: sub(lethal) effects

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Justification for type of information:

In the aquatic environment magnesium ethanolate decomposes within minutes by hydrolysis into ethanol and magnesium hydroxide. Both hydrolysis products are natural occuring substances and no long term aquatic toxicity was observed for the two hydrolysis products. Ethanol is readily biodegradable. Magnesium ethanolate, magnesium hydroxide and ethanol are of low acute toxicity to fish and do not meet the criteria for classification under the CLP and REACH Regulation. Magnesium ethanolate will be used as a catalyst (intermediate). Long-term studies with fish are not indicated with magnesium ethanolate, as there is no evidence for long-term aquatic toxicity arising either from the test substance itself or from its hydrolysis products, magnesium hydroxide and ethanol and exposure to the environment is negligible.

Reference 2

Endpoint:

fish short-term toxicity test on embryo and sac-fry stages

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 212 (Fish, Short-term Toxicity Test on Embryo and Sac-Fry Stages)

Deviations:

yes

Remarks:

multiple experiments carried out where exposure was for only a few hours at different critical parts of gestation period

GLP compliance:

not specified

Analytical monitoring:

yes

Remarks:

ethanol is analyzed in the exposed zebrafish

Details on sampling:

three embryonic stages for analysis: 5.25– 6.25 hpf, the first hour of zebrafish gastrulation;
8–10 hpf, the transition from gastrulation to neurulation in zebrafish; and 24–27 hpf, a key CNS
developmental stage characterized by the formation of the 5-vesicle brain.

Vehicle:

no

Details on test solutions:

Zebrafish embryos in fish water containing a 1:500 dilution of 0.1% methylene blue (to prevent fungal
infection) were exposed to 0.5%, 1%, 3% or 5% ethanol from 5.25–6.25, 8–10 or 24–27 hours post fertilisation

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

Zebrafish were obtained from Zebrafish International Resource Center. The AB strain was used in these
studies and fish were housed in automatic fish housing systems (Aquaneering, San Diego, CA) at 28.5°
C

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

27 h

Remarks on exposure duration:

Three experiments, three exposure periods 5.25-6.25, 8-10, 24-27 hours post fertilisation.

Hardness:

freshwater

Test temperature:

28°C

Nominal and measured concentrations:

0.5%, 1%, 3% or 5%

Details on test conditions:

TEST SYSTEM
- Test vessel: 6 well plates
- Renewal rate of test solution (frequency/flow rate): not applicable.
- No. of fertilized eggs/embryos per vessel: 8-30/well.
- No. of vessels per concentration (replicates): 3

RANGE FINDER STUDIES: yes

EFFECT PARAMETERS MEASURED:Embryos were examined for morphological phenotypes characteristic of fetal alcohol syndrome (midbrain/hindbrain boundary and eye development). Embryos were also analyzed by in situ hybridization for changes in expression of defined cell markers for neural cell types that are sonic hedgehog-dependent

OTHER: At the end of each exposure period, the fish water containing ethanol was removed, embryos were washed once with fresh fish water, and then transferred to fresh fish water for the remainder of the experimental time-course.

Reference substance (positive control):

no

Duration:

27 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: developmental effects (morphological, gene expression)

Remarks on result:

other: For all time periods examined results were the same

Long term tests are expected to cover all stages of the life cycle to give an accurate estimate of chronic toxicity. It is therefore expected that the embryo and sac fry test would be less sensitive than a full early life stage test. However, for substances with a log Kow <4 that have a non specific narcotic mode of action (such as ethanol) the difference in sensitivity between the two tests would be expected to be small. This study only examined acute exposures at critical periods of gestation but is still useful as contributing information to the overall toxicity to developing fish embryos.

Validity criteria fulfilled:

not specified

Executive summary:

In a study that examined the effect of short term acute exposure to ethanol at critical stages of zebrafish embryo development during the first 27 hours post fertilisation, ethanol was found to exhibit a no effect level of 1000mg/l for all developmental end points examined.

Reference 3

Endpoint:

fish short-term toxicity test on embryo and sac-fry stages

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Published study containing sufficient details to judge it as reliable with restrictions. Not all experimental parameters reported

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 212 (Fish, Short-term Toxicity Test on Embryo and Sac-Fry Stages)

GLP compliance:

not specified

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebrafish
- Strain: Transgenic line Tg(nkx2.2a:mEGFP)
- Source: Dr. Joan K. Heath

METHOD FOR PREPARATION AND COLLECTION OF FERTILIZED EGGS
- Homozygous Tg(nkx2.2a:mEGFP) were crossed with wild type fish to obtain 100% transgenic embryos for chemical exposure experiments. Embryos were collected and incubated in egg water at 28C. Following the protocol of DarT where embryos were transferred to test solutions about 60 minutes after initiation of spawning, the chemical exposure was standardised here at ~3 hpf by selecting alive, well developing embryos for chemical treatment.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

120 h

Nominal and measured concentrations:

Main study: 0.1%, 0.25%, 0.5%, 1%, 2%.
Follow up study: 0.025%, 0.05%.

Details on test conditions:

TEST SYSTEM
- Test vessel: 6 well plates
- Renewal rate of test solution (frequency/flow rate): daily.
- No. of fertilized eggs/embryos per vessel: 50/well.
- No. of vessels per concentration (replicates): 4

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : GFP fluorescence was observed and photographed under a fluorescent microscope with a GFP filter. Length of whole body, central nervous system (CNS) and axon. Observations made at 8, 24, 48 and 96 hpf (n=5).

VEHICLE CONTROL PERFORMED: no

RANGE-FINDING STUDY: Yes

Reference substance (positive control):

no

Duration:

120 h

Dose descriptor:

NOEC

Effect conc.:

250 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: shortening of motoneuron axons

Duration:

120 h

Dose descriptor:

NOEC

Effect conc.:

1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: body length, hatching, heartbeat, tail detachment

Remarks on result:

other: Heartbeat and tail detachment at 48hrs, hatching at 96hrs

Details on results:

- Mortality/survival at embryo and larval stages: dose-dependent decrease of survival rates seen. Most mortality in time range 8–24 hpf.
- Data for length and weight of surviving fish: dose-dependent decrease hatching rates with suppression of the hatching rates of 34%–56% at top dose.
- Type of and number with morphological abnormalities: statistically significant changes seen at higher doses in hatching, heartbeat, tail detachment, and somite morphology. Reduced axon length seen at all concentrations. A follow up study using lower dose concentrations was performed to determine the NOAEL for this end point.
Any other information on results incl. tables
Long term tests are expected to cover all stages of the life cycle to give an accurate estimate of chronic toxicity. It is therefore expected that the embryo and sac fry test would be less sensitive than a full early life stage test. However, for substances with a log Kow <4 that have a non specific narcotic mode of action (such as ethanol) the difference in sensitivity between the two tests would be expected to be small. An OECD 212 study can therefore be considered as an appropriate protocol to assess the long term toxicity of ethanol to fish.

Validity criteria fulfilled:

not specified

Executive summary:

In a study which approximated to an OECD212 Embryo and Sac-fry stage test, ethanol was found to exhibit a no effect level of 1000mg/l or more for most end points. However, for the end point of shortening of motoneuron axons (the study was specifically interested in neurotoxicity end points) a lower NOEC of 250mg/l was observed. Long term tests are expected to cover all stages of the life cycle to give an accurate estimate of chronic toxicity. It is therefore expected that the embryo and sac fry test would be less sensitive than a full early life stage test. However, for substances with a log Kow <4 that have a non specific narcotic mode of action (such as ethanol) the difference in sensitivity between the two tests would be expected to be small. An OECD 212 study can therefore be considered as an appropriate protocol to assess the long term toxicity of ethanol to fish.

 

Description of key information

In the aquatic environment magnesium ethanolate decomposes within minutes by hydrolysis into ethanol and magnesium hydroxide. Both hydrolysis products are natural occuring substances. Magnesiumethanolate and ethanol are readily biodegradable. For these reasons no long term aquatic toxicity is expected for magnesiumethanolate or its hydrolysis products ethanol and magnesiumhydroxide.

Magnesium ethanolate will be used as a catalyst (intermediate). Long-term studies with fish are not indicated with magnesium ethanolate, as there is no evidence for long-term aquatic toxicity arising either from the test substance itself or from its hydrolysis products, magnesium hydroxide and ethanol and exposure to the environment is negligible.