Bisisobutyryl peroxide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.02 mg/L

Assessment factor:

1 000

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:

10 000

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

0.6 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.13 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.013 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:

0.01 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

PNEC calculations for diisobutyryl peroxide were conducted out on main degradation product isobutyric acid due to the very rapid hydrolysis of diisobutyryl peroxide. Concentrations of isobutyric acid were theoretically calculated from ecotoxicity studies on the parent test material / product presuming 32.4% degradation (as indicated in company data) of the parent peroxide to isobutyric acid. Assessment factors as indicated in the relevant technical guidance document was followed without exception. It should be taken into consideration that measurements made during the investigation of degradation components are representative of a worst case scenario. Primarily due to the inaccuracies associated with such measurements (due to volatility for example) as well as the likelihood that the high concentrations of the parent peroxide were not fully dissolved during the short duration of the analytical test. In the ecotoxicity tests the preparation time was significantly longer and percentage degradation to isobutyric acid is expected to be higher, likely somewhere between the measured and theoretical maximum concentrations of isobutyric acid.

Conclusion on classification

For ecotoxicity testing the parent material was degraded fully and tested for effect on the test organisms. This was considered the most relevant manner to determine aquatic hazard of the unstable parent material as a whole. See classification information below:

Acute classification

The existing acute data for Daphnia (open system), Algae and Fish all have EL50 values of > 100 mg/L (loading). For algae the EL10

was determined as 35 mg/L. Due to worst case data being relevant for classification and labeling the effects to invertibrates in a closed system (EL50 3.8 mg/L) should be mentioned here.

As all effect values are above 1 mg/L, there is no acute classification for this substance.

Chronic classification

Diisobutyryl peroxide should be classified as readily biodegradable, and the measured log Kow is 2.6. The only chronic data available is 72 h ErC10 algae, 35 mg/L, loading). When chronic data for less than 3 trophic levels are available the classification is assessed using both the existing chronic and acute data, and the most stringent outcome is chosen.

Based on chronic data: (72 h EL10 algae, 35.0 mg/L loading): No classification

Based on acute data (NOECs > 1 mg/L loading): No classification

Category chronic 4 evaluation - Not applicable

Most stringent outcome: None

Overall classification: None