tert-butyl 2-ethylperoxyhexanoate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.002 mg/L

Assessment factor:

50

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.004 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0 mg/L

Assessment factor:

500

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

0.64 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

0.622 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.062 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:

no exposure of soil expected

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

PNEC freshwater sediment:

K_(susp-water) = 81.9

RHO_(susp) = 1150

Conversion factor (wwt -> dwt): 4.6

PNEC_freshwater sediment

= (K_(susp-water)/ RHO_(susp))*PNEC_water * 1000

= (81.9/1150)* 1.9E-03 *1000

= 0.135 mg/kg wwt

= 0.622 mg/kg dw

 

PNEC marine water sediment:

K_(susp-water) = 81.9

RHO_(susp) = 1150

Conversion factor (wwt -> dwt): 4.6

PNEC_marine water sediment

= (K_(susp-water)/ RHO_(susp))*PNEC_marine water* 1000

= (81.9/1150)*1.9E-04* 1000

= 1,35E-02 mg/kg wwt

= 0.0622 mg/kg dw

Justification for no PNEC soil derivation

Direct and indirect exposure of the test item to soil is highly unlikely. Due to the unstable nature of organic peroxides, it can be assumed that upon contact with soil and organic matter, the test item undergoes rapid degradation resulting in the formation of respective alcohols and acids. Thus, toxicity to soil organisms was considered scientifically not justified.

Further, according to the Guidance on information requirements and chemical safety assessment Chapter R.7.11.5.3, the PEC and PNEC for the terrestrial compartment do not have to be calculated if exposure to soil is negligible. Based on the examples given this is applicable if e.g. potential land spreading or aerial deposition of the substance and other pathways such as irrigation or contact with contaminated waste can be considered unlikely.

Taking the complete life cycle of this substance into careful consideration including the risk management measures in place, these qualifications are fulfilled.

This is confirmed by the following argumentation when looking at the several routes chemicals can reach the soil:

1. Application of sewage sludge in agriculture / land spreading

In general, the release of organic peroxides from the production plant into the sewage is very limited, not to say completely negligible. However, in rare cases when organic peroxides reach the sewage of a plant production or a downstream user’s plant, these are treated with other substances in dedicated industrial sewage treatment plants. The activated sludge stemmed from these industrial sewage treatment plants are further extracted and treated as chemical waste.

The waste water from production plant is treated on site (at least a physical/chemical treatment, which will neutralize potential residual organic peroxide), which is usually followed by a biological treatment. So, it is expected that organic peroxides are not present in sludge. In addition, land spreading of sewage sludge is strictly interdicted. Any sewage sludge has to be disposed e.g. by incineration.

Regarding the rest of the lifecycle, organic peroxides are mainly used as cross-linking agent/polymerization initiator for the production of resins/rubbers/polymers. Based upon the fact that organic peroxides are totally consumed during the process (>99%, which is confirmed by the release factor to sewage for curing agents from ESD n°3), the soil is not exposed to organic peroxides via use of sludge.

As a consequence, exposure of soil to organic peroxides via the application of sewage sludge in agriculture can be excluded.

2. Direct application of chemicals

Based on the uses inventoried for organic peroxides there is no direct application of these substances on the soil compartment. Indeed, all uses are within industrial settings.

3. Deposition via other pathways such as irrigation or contact with contaminated waste

Contact with contaminated waste or deposition via e.g. irrigation processes is negligible. Any waste from production plant is treated on site and the organic peroxides are totally consumed during the industrial end uses. In addition, there are risk management measures in place to control the deposition via any other pathways such as irrigation. In case contamination takes place, the waste water is disposed e.g. via STP with high efficiency or incineration (see also 1. above).

 

4. Deposition from the atmosphere / aerial deposition of the substance

Deposition from the atmospheric compartment involves volatilization, vaporization or direct release of a considered substance into the atmosphere. Due to their dangerous intrinsic physico-chemical properties, organic peroxides are carefully handled in (semi-)closed systems and their transport, production and use are ruled by several regulations. This is also in line with the release factor to atmosphere for curing agents from ESD n°3. Based on organic peroxides uses, deposition on soil from the atmosphere is also not expected. In addition,dedicated equipment with high efficiency requiring only minor cleaning processes is implemented to prevent aerial deposition of the substance (e.g. adsorption units, off-gas cleaning, air-filtration using high efficiency air filter, waste gas membrane separation, biological treatment, thermal treatment, etc.).

 

Based on these arguments any exposure to soil is highly unlikely and is considered negligible. No test is proposed for the soil compartment. Further, as the criteria to waive the derivation of both PEC and PNEC for the soil compartment are fulfilled, these effect concentrations have not been calculated.

Conclusion on classification

Acute toxicity:

Algae is the most sensitive species to the acute toxic effects of the test item with an acute ErC50 of 0.4394 mg/L. Based on the these data, the substance has to be classified with regard to acute environmental toxicity as acute aquatic cat.1 (H400: Very toxic to aquatic life, M=1) according to Regulation (EC) No 1272/2008 (CLP/GHS).

Chronic toxicity:

Algae are the most sensitive species to toxic long term effects of the test item with a chronic NOEC of 0.018 mg/L. As the test item is readily biodegradable, on the basis of acute and chronic toxicity data the substance is classified as chronic aquatic cat. 2 (H411: Toxic to aquatic life with long lasting effects) according to Regulation (EC) No 1272/2008 (CLP/GHS).