Isobutyl methacrylate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.021 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.2 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.002 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

10 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

5.89 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.589 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

1.16 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

PNEC aqua (freshwater)

Acute toxicity studies were conducted with iBMA in fish, daphnia and algae. Chronic studies with iBMA are available for daphnia (QSAR calculation) and algae. The PNEC aqua (freshwater) was based on the NOEC of 2.1 mg/L (derived from daphnia QSAR calculation). An assessment factor of 100 was applied to the NOEC to calculate the PNEC aqua (freshwater) in accordance with Guidance on information requirements and chemical safety assessment, Chapter R.10: Characterisation of dose [concentration]-response for environment, 2008.

PNEC aqua (marine)

No tests with marine species are available. The PNEC aqua (marine water) was based on the NOEC of 2.1 mg/L (derived from daphnia QSAR calculation). An assessment factor of 1000 was applied to the NOEC to calculate the PNEC aqua (marine water) in accordance with Guidance on information requirements and chemical safety assessment, Chapter R.10: Characterisation of dose [concentration]-response for environment, 2008.

PNEC aqua (intermittent releases)

The PNEC aqua (intermittent releases) was based on the lowest acute toxicity value of 20 mg/L for Oncorhynchus mykiss. Based on the available data set, an assessment factor of 100 was applied to the lowest EC/LC50 to calculate the PNEC aqua (intermittent releases) in accordance with Guidance on information requirements and chemical safety assessment, Chapter R.10: Characterisation of dose [concentration]-response for environment, 2008.

PNEC STP

In a range finder for a MITI biodegradation test there was no bacterial toxicity (respiration of activated sludge) up to 100 mg/L, the maximum concentration tested. An AF of 10 is applied to the available activated sludge respiration test (exposure duration: 6 d), according to table R.10-6 from guidance document.

PNEC sediment (freshwater, marine)

No toxicity data for sediment dwelling organisms are available. Thus, the PNEC for freshwater as well as marine sediment has been calculated with the equilibrium partitioning method using EUSES 2.1.

The following data have been taken into account for the calculation:

Molecular weight [g/mol]	142.2
Melting point [°C]	-35
Boiling point [°C]	155
Vapour pressure [hPa], 20°C	2.11
Water solubility [mg/L], 25°C	470
Log Kow	2.95
Koc (Kow method) L/kg	2767
PNEC aqua, freshwater [mg/L]	0.021

PNEC air

A PNEC air was not calculated for iBMA since the substance is rapidly degraded in air. This indicates that there would be only little accumulation of the test substance in the air.

PNEC soil

No toxicity data for soil organisms are available. Thus, the PNEC soil has been calculated with the equilibrium partitioning method using EUSES 2.1.

The following data have been taken into account for the calculation:

Molecular weight [g/mol]	142.2
Melting point [°C]	-35
Boiling point [°C]	155
Vapour pressure [hPa], 20°C	2.11
Water solubility [mg/L], 25°C	470
Log Kow	2.95
Koc (Kow method) L/kg	2767
PNEC aqua, freshwater [mg/L]	0.021

   

PNEC oral

A PNEC oral was not calculated for iBMA since the substance is readily biodegradable. Due to the well investigated metabolic pathways the probability of being rapidly metabolised in exposed organisms is high. Together with the reported log Kow of 2.95 this indicates that there would be no significant potential for biomagnification of the test substance in the food chain.

Conclusion on classification

iBMA is moderately toxic to aquatic organisms but at the same time it is readily biodegradable and not bioaccumulable and, hence, no classification is required according to CLP criteria (1272/2008/EC).

According to UN-GHS rev. 3 (2009) the substance is classified in category 3 for acute aquatic toxicity.