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Description of key information

No data on skin and eye irritation is available with HiMo LAB.  Skin and eye irritation studies data from LAB (C10-16, CAS no: 68442-69-3), HAB (CAS no: 84961-70-6) were used to cover these endpoints.  Based on the woe approach from supporting analogues, HiMo LAB should not be classified as skin or eye irritant according to CLP and EC.

Key value for chemical safety assessment

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. 

To assess the skin and eye irritation 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).

Skin irritation:

The study examined the potential of HAB to cause irritation to skin according to OECD guideline 405. The test substance was placed on the skin of 6 male rabbits for 4 hrs, and covered with a semi-occlusive patch. After 4 hrs, the test substance was removed with warm water. The animals were scored for signs of edema and erythema according to the Draize scale at 3/4, 24, 48, and 72 hrs. Because symptoms were not fully resolved at the end of 72 hrs, the study was extended through 10 days after exposure. Signs of erythema (maximum score of 2) and edema (maximum score of 2) were seen at the 3/4 hr observation. These symptoms were fully resolved by the day 8 observation. Signs of discoloration, drying and cracking were seen starting at the 72 hr observation. By the day 10 observation, all of these symptoms were resolved as well. The primary irritation index was 1.25, and all symptoms were fully reversible.

The study examined the potential of LAB to cause skin irritation according to EEC guideline. 6 rabbits were exposed to undiluted test substance on shave skin for 4 hrs. After the exposure the animals were scored for skin irritation, and were scored again at 24, 48, and 72 after end of exposure. Since symptoms were not fully resolved, further observations were made at 5 and 7 days after end of exposure. At the 24 hr observation, all animals showed signs of erythema (maximum score of 2), and one animal showed signs of edema (score of 1). There were no signs of edema in any animal at the 48 hr observation. Erythema persisted in all animals through day 5, and in 3 of the animals, erythema was not fully resolved at the end of the experiment on day 7. Though all symptoms of irritation were mild, the irritation was not fully reversible within the study period. The test substance is considered mild irritating to the skin of rabbits.

Eye irritation:

The study examined the potential of HAB to cause irritation to eyes according to OECD guideline 406. 0.1 ml of test substance was placed in one eye of three male rabbits. The untreated eye served as control. The animals were examined for signs of irritation at 1, 24, 48, and 72 hours after application. All three animals showed signs of conjunctival erythema (score of 1) at the 1 hr observation. By the 48 hr observation, these symptoms had resolved in all but one animal. This animal continued to show irritation at the 72 hr observation. For this reason, the study was extended to determine the reversibility of the symptoms. At the next observation at day 6, symptoms had resolved in all animals. The mean irritation score was 0.55.

The study examined the potential of LAB to cause eye irritation according to EEC guideline. 0.1 ml of test substance was placed in one eye of 6 rabbits. The untreated eyes served as controls. The eyes were examined at 1, 24, 48, and 72 hrs, and 7 days after start of exposure for signs of irritation. No signs of irritation were seen in any animal at any observation. The test substance is considered not irritating to eyes.

Justification for classification or non-classification

The substance should not be classified according to classification criteria of Directive 67/548/EEC and Regulation (EC) No 1272/2008. Although the symptoms were fully reversible, signs of discoloration, drying and cracking was observed.

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