Benzene, C20-24 (even numbered) sec-alkyl derivs.

Endpoint summary

Description of key information

No data on acute toxicity is available with HiMo LAB.  Acute toxicity studies data from LAB (C10-16, CAS no: 68442-69-3), HAB (CAS no: 84961-70-6)  and Benzene, mono-C12-14-alkyl derivs., fractionation bottoms  (CAS No: 68515-32-2) were used to cover these endpoints. The oral LD50 value for HiMo LAB is considered to be >2000 mg/kg bw.  The dermal LD50 in rats was > 3600 mg/kg bw.  The oral LD50 value for HiMo LAB is considered to be >2000 mg/kg bw

Additional information

Benzene, C16-24 alkyl derivatives are also known as High Molecular Weight Linear Alkylbenzenes (HiMo LAB).  The substance is a UVCB. Because of their high molecular weight, they are very similar in composition and properties to the heavy alkylate bottoms (HAB). Based on these structural and functional similarities, data on LAB (CAS no: 67774-74-7) being registered under REACH, LAB Alkylate Bottoms (CAS no: 85117-41-5) described in OECD SIDS dossier, and HAB (CAS no: 84961-70-6) being registered under REACH are suitable as supporting studies in case where specific data on the HiMo LAB is lacking. 

Oral acute toxicity:

To assess the acute oral toxicity profile of the substance, structral analogue approach was used from Benzene, C10-16-alkyl derivs. (LAB, CAS No: 68442-69-3) and Benzene, mono-C10-13-alkyl derivatives, distillation residues (HAB, CAS No: 84961-70-6).

This study examined the acute toxicity of LAB to rats according to EEC guideline. 5 male and 5 female rats were given a dose of 5000 mg/kg bw of test substance by oral gavage. The animals were then monitored for the next 14 days for mortality and signs of toxicity. At the end of the study, the animals were sacrificed and gross pathology performed. No animals died during the study. The LD50 for rats by oral exposure is > 5000 mg/kg bw.

This study examined the acute oral toxicity of HAB to rats. A group of 5 male and 5 female rats were given a dose of 2000 mg/kg bw test substance. The rats were then monitored over the next 14 days for clinical signs and mortality. Body weights were taken on days 0, 7, and 14 of the study. At the termination of the study, all animals were sacrificed, and examined for macroscopic abnormalities. No animals died during the study. No adverse effects to body weight or clinical signs were noted. The acute oral LD50 for male and female rats was > 2000 mg/kg bw.

Acute inhalation toxicity:

In accordance with column 2 of REACH Annex VIII, in addition to the oral route, for substances other than gases, an acute toxicity study for at least one other route is required. The choice of the second route will depend on the nature of the substance and the likely route of human exposure. As dermal is the most likely route of exposure and acute dermal toxicity data is available, no acute inhalation study is deemed necassary.  

                                                                                                                                 

                                                                                                                                                                                

Acute dermal toxicity:

No study on acute toxicity is available with the substance. To cover the acute dermal toxicity endpoint of substance, LAB (CAS no: 67774-74-7) and Benzene, mono-C12-14-alkyl derivs., fractionation bottoms (CAS No: 68515-32-2) was used as supporting structural analogue substance.

The study determined the acute dermal toxicity of the LAB in rats according to OECD 402 guideline. 5 male and 5 female rats were exposed to 2000 mg/kg bw of test substance dermally. Exposure lasted 24 hrs, after which the test substance was removed by washing. The animals were observed for the next 14 days for clinical signs and mortality. All animals were necropsied at the end of the experiment. No animals died during the studies. The dermal LD50 in rats is > 2000 mg/kg bw.

The study examined the acute dermal toxicity of Benzene, mono-C12-14-alkyl derivs., fractionation bottoms. Groups of 5 male and 5 female rats were exposed to concentrations of 0, 3600 (males), and 4300 mg/kg bw (females) dermally. Animals were observed for the next 14 days for mortality and clinical signs. Animals were weighed every 7 days. At the end of the study, animals were necropsied. No animals died during the study, and no adverse clinical signed were noted. Body weight gains of treated animals were also comparable to controls. The acute dermal LD50 for both female rats was > 4300 mg/kg bw, and male rats was > 3600 mg/kg bw.

Justification for classification or non-classification

The available acute toxicity studies of supporting structural analogue substance demonstrate that HiMO LAB is of low acute toxicity. HiMo LAB should not be classified for acute toxicity according to CLP regulation and DSD criteria.