Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability

The photodegradation of m- and p-diisopropylbenzene in air by reaction with OH radicals was calculated using EPIWIN v3.20, AOPWIN v1.92. Based on the reaction rate constants k(OH)= 15.524 x 10E-12 cm³/molecule x sec (m-diisopropylbenzene) and k(OH)= 10.1158 x 10E-12 cm³/molecule x sec (p-diisopropylbenzene) and assuming a OH radical concentration of 5 x 10E5 radicals/cm³ (24 h d) half-lives of 24.8 h (m-diisopropylbenzene) and 38.07 h (p-diisopropylbenzene) were calculated. For m- diisopropylbenzene a half-life of 8.268 hours was calculated based on the aforementioned rate constant and assuming a hydroxyl radical concentration in the atmosphere of 1.5E6 OH/cm3 (12 h day); accordingly a half-life time of 12.688 hours was calculated for p-diisopropylbenzene based on the above cited rate constant and assuming a hydroxyl radical concentration in the atmosphere of 1.5E6 OH/cm3 (12 h day). In a study conducted according to OECD Guideline 111 (Hydrolysis as a Function of pH), diisopropylbenzene proved to be resistant to hydrolysis: the chemical was stable at pH 4, 7 and 9 at 50 degree for five days.

Biodegradation

In a study conducted according to OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II)), diisopropylbenzene proved to be not inherently biodegradable (0% by BOD after 14 days; 0% by GC after 14 days).

Bioaccumulation

In a study conducted according to OECD Guideline 305 E (Bioaccumulation: Flow-through Fish Test) Cyprinus carpio were exposed to m-/p-diisopropylbenzene concentrations of 2 and 20 µg/L for 56 d. For p-diisopropylbenzene BCF values ranging from 530 to 2300 at 20 µg/L and 512 - 2960 at 2 µg/L were determined and for m-diisopropylbenzene BCF values ranging from 503 to 1680 at 20 µg/L and 546 to 3210 at 2 µg/L. Thus a moderately high potential for bioconcentration is to be expected (BCF < 5000)

Transport and distribution

The soil sorption coefficient Koc of diisopropylbenzene was calculated measured according to an EC guideline HPLC method. LogKoc was found = 3.8.

Calculation using EPIWIN v3.20, PCKOCWIN v1.66 yielded a value of 4036 (log Koc=3.606) indicating a sorption onto soil organic matter. The calculation of Koc based on molecular connectivity indexes yielded a value of 4000 and indicates that a sorption of diisopropylbenzene onto soil organic matter is to be expected.

Based on the calculated Henry's Law constants (>1000 Pa x m³/mole), it is to be expected that m- and p-diisopropylbenzene are highly volatile from aqueous solution. According to the Mackay Level III calculation, the main target compartment of the distribution is air (ca. 99%) if the chemical is released into the air. If the chemical is released to the hydrosphere, the main target compartments are water (ca. 20 -23%) and sediment (ca. 75 -80%) and if the chemical is released to soil, the chemical remains predominantly in the soil compartment (ca. 98%).

Monitoring Data

Air

Among others, diisopropylbenzene was quantitatively detected in kitchen waste exudate (n=7; HRGC-MS) as volatile compound. It was not detected in kitchen waste samples, garden waste, and in samples of infected building material. Diisopropylbenzene was detected in atmospheric grab samples collected in the vicinity of an oil fire using GC/MS. Diisopropylbenzene was found in a concentration of 1.04 mg/m³.

Water

Tap water from the Kitakyushu Municipal Institute of Environmental Health Sciences (Japan) was examined for the presence of trace organic substances by using the Amberlite XAD-2 resin adsorption method and GC/FID. m-/p-Diisopropylbenzene were detected in tap water but not quantified.

Natural occurrence

Diisopropylbenzene is reported to occur naturally in coal.