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EC number: 203-326-3 | CAS number: 105-74-8
The biological results /test part one) can be summarized as follows (on the basis of loading rates and mean measured test item concentrations):
(based on loading rates)
(based on mean measured concentrations)
n.d.: could not be determined
The biological results (test part two) can be summarized as follows (on the basis of loading rates of the test item):
n.d.: could not be determined
The influence of the test item Dilauroyl peroxide and its eventual degradation products on the growth of the freshwater green algal species Pseudokirchneriella subcapitata was investigated in 72‑hour static tests according to OECD Guideline 201 (2006), the EU Commission Directive 92/69/EEC, C.3 (1992), and the Commission Regulation (EC) No 440/2008, C.3.
The test item Dilauroyl peroxide was dispersed in test water at loading rates of 1.0 and 100 mg/L. The dispersions were stirred for 72 hours in order to dissolve a maximum amount of the test item in the test water. After the stirring period, the dispersions were let to settle in a separation funnel and the middle layers were used as test media.The preparation of the test media was based on the OECD Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures, 2000.
Half of the volumes of the test media were used immediately to examine the influence of the test item Dilauroyl peroxide on the algal growth (test part 1). The remaining volumes of the test media were left in a closed system for ageing over a period of 7 days in order to allow the test item to degrade and to test the influence of eventual degradation products of the test item on the algal growth (test part 2). The test duration of both tests was 72 hours.
Control groups were run in parallel. The control medium for the degradation products test (test part 2) was left in a closed system for ageing over a period of 7 days.
At the start of the Dilauroyl peroxide parent test (test part 1)test item concentrationsof0.24 and 2.1 mg/Lwere measured in the test media with the loading rates of 1.0 and 100 mg/L, respectively. Thus, the measured concentrations were above the water solubility limit of the test item(0.06 mg/L; study MIRA20090934-water solubility, Akzo Nobel) due to undissolved test material in the test media. During the test period of 72 hours, the test item concentrations in the test media decreased. At the end of the test, the measured concentrations were 0.034 and 0.52 mg/L,respectively.
The mean measured test item concentrations were calculated as the geometric means of the concentrations measured at the start and at the end of the test(test part 1):
Mean measured concentration(mg/L)
The biological resultsof the Dilauroyl peroxide parent test (test part 1)were related to the loading rates and to the mean measured concentrations of the test item.The biological resultsof the degradation products test (7-days aged test media, test part 2)were related to the loading rates of the test item.
The biological results of theDilauroyl peroxide parent test (test part 1) were as follows (based on the loading rates and mean measured concentrations of the test item):
The biological results of the degradation products test(7-days aged test media, test part 2) were as follows (based on the loading rates of the test item):
As the water solubility of the test item was determined to be 0.06 mg/L (study MIRA20090934-water solubility, Akzo Nobel) it can be concluded that the test item Dilauroyl peroxide and its degradation products have no biological relevant toxic effects on the growth of Pseudokirchneriella subcapitata up to the test item’s water solubility limit under the conditions of the test.
One valid algae study carried out in a closed system is available. No effects were found using the WAF method up to 100 mg/L corresponding to the limit of solubility or higher.
2 studies on algae are available, one invalid study (Gancet, 2008b) which was performed using filtered stock solutions, perhaps removing any dissolved substance present, and a reliable GLP study on Pseudokirchneriella subcapitata following the 2006 updated OCED 201 (Weber, 2010b)
. This study tested the influence of the test substance which is poorly soluble and its degradation products on growth inhibition under closed conditions. Briefly two stock solutions were first prepared at loading rates of 1 mg/L and 100 mg/L with test media. Stock solutions were stirred for 72h (the time believed from preliminary studies to be the optimal time for maximising the parent compound concentration in aqueous solution) and then left in a separation funnel for phase separation. Middle layers of the stock solutions were then split into two batches: one batch for direct use and a second aged for 7 days, in order to allow hydrolysis products of the substance to be present should it be likely to degrade abiotically. After 72h of exposure, mean measured concentrations in the first test were respectively 0.089 mg/L for the stock solution at a loading rate of 1 mg/L and 1.0 mg/L for the stock solution at a loading rate of 100 mg/L. Both of these concentrations are known to be well over the aqueous solubility limit of the substance. No effects were observed in either of the groups (parent or potential degradation products tested. It was concluded that neither the substance nor potential degradation products had any effects up to the limit of solubility.
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