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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Stability

The photodegradation of cumene hydroperoxide in air by reaction with OH radicals was calculated using EPIWIN v3.20, AOPWIN v1.92. Based on the reaction rate constant k(OH)=8.63 x 10E-12 cm³/molecule x sec (25°C) and assuming a OH radical concentration of 5 x 10E5 radicals/cm³ (24 h d) a half-life t1/2=44.6 h was calculated.

The hydrolysis as a function of pH of1-methyl 1-phenylethyl hydroperoxidewas assessed according to the OECD guideline 111. According to the results of this study,1-methyl 1-phenylethyl hydroperoxidecan be considered as stable at pH 4, 7 and 9.

At pH 1.2, the test item is hydrolytically unstable. The half-lives were respectively 14.1, 53.3, 311(estimation) and 1386 hours for the temperatures 50, 37, 25 and 15°C.

Cumene hydroperoxide is a strong oxidant. The O-O bond is unstable because of oxygen oxidation degree of -1. So the peroxide functional group is very reactive, particularly with reducing substances (for example organic matters), mineral acids. Therefore the substance is not expected to be persistent in the environment.

Biodegradation

The ready biodegradation of cumene hydroperoxide was investigated in a study conducted according toOECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)over a period of 28 days and using domestic activated sludge as inoculum source. The biodegradation rate was determined by measurement of CO2 evolution. Inoculum blank, procedural/functional control with the reference substance sodium benzoate, and toxicity control using ca. 11 mg TOC/L test substance and 20 mg TOC/L reference compound were performed.The test item proved to be not readily biodegradable under the test conditions employed (3% biodegradation after 28 d). The functional control reached the pass level >60% biodegradation after 14 d. In the toxicity control containing both test and reference item 40% biodegradation based on ThCO2 occurred within 13 d thus indicating that the test substance was not inhibitory at the concentration tested. The ready biodegradability of cumene hydroxide was also investigated in a further study conducted according toOECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test). Over a period of 28 days and using activated sludge as inoculum source, the biodegradation rate was determined by measurement of CO2 evolution. Inoculum blank, procedural/functional control with the reference substance sodium benzoate, and toxicity control using 10 and 20 mg/L test item and 2 mg/L reference compound were performed.The test item proved to be not biodegradable under the test conditions employed(7% and 2% biodegradation after 28 d at test substance concentration of 10 and 20 mg/L).The functional control reached the pass level >60% after 14 d. In the toxicity control containing both test and reference item 45% biodegradation based on ThCO2 occurred within 5 d thus indicating that the test item was not inhibitory at the concentration tested.

Bioaccumulation

Based on the experimentally determined log Kow=1.6, a BCF below 1 was calculated, and therefore no bioaccumulation potential is to be expected.

Transport and distribution

Based on the results of a reliable study (Koc=39.8) a moderate sorption onto soil organic matter of cumene hydroperoxide is to be expected. According to the available data (calculated: 0.098 and 1.32 Pa x m³/mole //experimental: 0.022 Pa x m³/mole at 25°C each) on Henry's Law constant, cumene hydroperoxide can be regarded as moderately volatile from aqueous solution.

Environmental data

Volatile pollutants produced from several rubber goods manufacturing processes were collected on activated charcoal and after desorption analyzed by GC/MS. Cumene hydroperoxide was not detected in samples collected in the vulcanization areas of a shoe-sole factory and in the vulcanization and extrusion areas of a tire retreading factory (<1 µg/m³). Cumene hydroperoxide was detected in samples collected in the extrusion areas of an electrical cables insulation plant in concentrations ranging from 0 to 60 µg/m³. The authors presumed dicumyl peroxide as probable source.

Additional information on environmental fate and behaviour

The photochemical decomposition of cumene hydroperoxide in the absence of oxygen was investigated in n-hexane and carbon tetrachloride solution. The degradation products were identified and the quantum yield determined. As degradation products were identified in n-hexane solution and

a. irradiation at 313 nm: mainly alpha, alpha'-dimethyl benzyl alcohol and to a lesser extent acetone, phenol, and water

b. irradiation at 253.7 nm: mainly alpha, alpha'-dimethyl benzyl alcohol and to a lesser extent acetone, acetophenone, phenol, and water.The mean quantum yield was determined to be 1.57

As degradation products were identified in carbon tetrachloride solution and

a. irradiation at 313 nm: mainly acetone and partly traces of alpha, alpha'-dimethyl benzyl alcohol, alpha-methyl styrene, acetophenonene (phenol was only detected once in the three replicates in appreciable amounts)

b. irradiation at 253.7 nm: mainly acetone, and alpha-methyl styrene and phenol. The mean quantum yield for this reaction was determined to be 0.75.