Di-tert-butyl α,α,α',α'-tetramethyl-(p-phenylenedimethylene) diperoxide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.004 mg/L

Assessment factor:

10

PNEC freshwater (intermittent releases):

0.004 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0 mg/L

Assessment factor:

100

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

100 mg/L

Assessment factor:

10

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

22.3 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

2.23 mg/kg sediment dw

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

5.15 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential to cause toxic effects if accumulated (in higher organisms) via the food chain

Additional information

One key study is available for each of the trophic compartments: Algae, Aquatic invertebrates and Fish: no effect of 1,4-bis(tert-butylperoxyisopropyl)benzene was observed up to its water solubility limit (0.04 mg/l).As a consequence, we propose to consider this water solubility limit as a NOEC value for the three considered trophic compartments. Then, we propose to use an assessment factor of 10 as recommended when NOEC are available for the three trophic compartments.

 

So and first of all, based on the full required set, 1,4-bis(tert-butylperoxyisopropyl)benzene has no effect and not only just no EC50 at the limit of solubility.The algae NOEC/ERC10 can also be considered not as a true NOEC but as a no effect at the maximum solubility tested. So first we are actually basing our factor of 10 on a no effect at all concentration (NEAAC) and not a NOEC.

 

Second, there are many substances for which the algae compartment is considered as the most sensitive species tested.This assumption relies on the fact that the substance having a direct effect on cell membranes, which makes small (unicellular) organisms more sensitive than larger ones. For these reasons, and if we consider algae as the most sensitive trophic compartment, the NOEC for the most sensitive species is available even if no chronic toxicity test results are available at the moment.

 

Third, there may be cases where we don’t expect algae to be more sensitive than the other species. For non-polar narcotics, the three studies tend to provide similar NOECs/EC10s. This is very clear for the algae, daphnid, fish non-polar narcotic QSARs which are almost identical.

For chronic studies there may be some differences between the QSARs but following critical body burden theory (Eisenbud, 1973; Foulkes, 1990), there is no reason why there would be a difference. Biological membrane disruption occurs at the same molar concentration but it can take a different time to reach those internal body residue concentrations.

 

That is the reason why we propose to consider the NOEC for algae as a NEAAC applicable to the three trophic compartments. Based on this assumption we propose to use an assessment factor of 10 as recommended when a NOEC value is available for the three trophic levels.

Conclusion on classification

To summarize no effect of 1,4-bis(tert-butylperoxyisopropyl)benzene was observed up to its water solubility limit (0.04 mg/l).

However, 1,4-bis(tert-butylperoxyisopropyl)benzene is not readily biodegradable (OECD 301D) and its log Kow was estimated at 7.3.

That is the reason why according to 67/548/ECC, 1,4-bis(tert-butylperoxyisopropyl)benzene is classified R53.

According to CLP the substance is classified "Aquatic chronic category 4".