Bisdecanoyl peroxide

Endpoint summary

Description of key information

Based on physico-chemical properties of the substance, absorption by inhalation and by oral route is possible; absorption following dermal exposure is anticipated very low.

There is no experimental toxicokinetic data on didecanoyl peroxide.

Absorption

Didecanoyl peroxyde is a solid substance with a molecular weight of 342.5 g/mol. The substance is very few soluble in water (0.12 mg/L). The measured logKow is > 6.2. The vapour pressure is very low: 0.04 Pa at 20 °C.

Didecanoyl peroxide has been shown to hydrolyse at several pH, with a half-time life of 377 h at 37°C, pH 7 and 492 h at 37 °C, pH 9. At pH 1.2, only the preliminary test is available: after 5 days at 50 °C, the hydrolysis rate was more than 80 %. From these data it can be assumed that at 37 °C the hydrolysis of didecanoyl peroxide remains very low at any pH. Therefore didecanoyl peroxide is anticipated to be absorbed unchanged in human body.

Oral absorption is favoured for molecular weights below 500 g/mol. Based on the very high logKow, didecanoyl is regarded as a lipophilic substance. Such a lipophilic compound should be poorly absorbed passively trough gastro-intestinal tract but may be taken up by micellular solubilisation. This mechanism may be of particular importance for didecanoyl peroxide as the substance is only very slightly soluble and would otherwise be poorly absorbed. No adverse effects were observed in oral toxicity studies. No effects were observed in the 28-day repeated dose toxicity study on the analogue substance dilauryl peroxide, up to 1000 mg/kg. Therefore it is not clear whether the substance is indeed absorbed by oral route; nevertheless as a worth case figure, the oral absorption factor should be considered close 100 %.

Based on the granulometry and on the very low vapour pressure of 0.04 Pa at 20 °C, inhalation exposure should be limited: 99.6% of particles of didecanoyl peroxide present a mean diameter higher than 125µm (70.8% of which are higher than 500µm) and only 0.4% of particles present a mean diameter lower than 100 µm. Nevertheless, if the inhalable fraction of substance reaches the lung, didecanoyl peroxide may be absorbed by micellular solubilisation (see above). The low water solubility may enhance penetration to the lower respiratory tract.

Based on physical – chemical properties of didecanoyl peroxide, the substance is not likely to penetrate skin to a large extent as the physical state of the substance, the high logKow value and the low water solubility do not favour dermal penetration. The dermal absorption of didecanoyl peroxide was estimated with IH SkinPerm v2.04 model (AIHA, 2018). Compared to in vitro data from OECD 428 studies, IH skinPerm allowed the estimation of the dermal absorption rate with a good confidence and a low frequency (ca. 2%) of underestimation for liquids (Arkema’s internal validation study, 2018). Uptake across the epidermis is expected to be low (3.1%). This was confirmed in an acute dermal toxicity study resulting in an LD0 value of more than 2000 mg/kg bw (with no associated clinical signs). In addition, didecanoyl peroxide was not shown to be a skin sensitizer and is only slightly irritating for skin.The skin absorption rate is therefore limited and considered at 10% for risk assessment.

 

Metabolism and excretion:

There is no experimental data on metabolism. Nevertheless, carboxylic acids may be produced in human body after enzymatic hydrolysis. Long (>12 carbon) chain aliphatic acids are absorbed in the intestine and distributed in the blood as chylomicrons. Aliphatic acids serve as a fuel for muscular contraction and general metabolism. They are consumed by mitochondria to produce ATP through beta oxidation (SIAP, Aliphatic Acids Category, 2014 [http://webnet.oecd.org/hpv/UI/handler.axd?id=0527b696-2db6-4635-ad7a-28534ddc597c]).

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

100

Absorption rate - dermal (%):

10

Absorption rate - inhalation (%):

100