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Description of key information

Oral LD50 (rat) > 10 mL/kg bw

Dermal LD 50 (rat) > 2920 mg/kg bw

Inhalation LC50 (rat) = 17300 - 23300 mg/m³

Key value for chemical safety assessment

Additional information

Oral

 

There are no data available on the acute oral toxicity of Hydrocarbons, C6-C10 (even numbered), n-alkanes, isoalkanes, >5% n-hexane. However, there are reliable data available for other category members. Thus, read-across was conducted based on a category read across approach.

The acute oral LD50value in rats was greater than 10 mL/kg for Hydrocarbons, C7-C9, isoalkanes in two studies performed according to a protocol similar to OECD 401. The test material produced no deaths at any dosage level tested (31.6-10000 µL/kg body weight). There were no pathological findings in any animal at autopsy following sacrifice. The animals at all dosage levels seemed normal in appearance and behaviour throughout the study period (ExxonMobil Chemical, 1961).

 

Inhalation

 

There are no data available on the acute toxicity of Hydrocarbons, C6-C10 (even numbered), n-alkanes, isoalkanes, >5% n-hexane, upon inhalation exposure. However, there are data available for other category members. Thus, read-across was conducted based on a category read across approach.

Hydrocarbons, C7-C9, isoalkanes, have been tested in several studies for acute inhalation toxicity following both standard (similar to OECD 403) and non-standard protocols.

In one study, 6 rats (male and female) were exposed to a nominal concentration of 21500 mg/m³ (21000 mg/m³ actual concentration) in a whole body chamber for 4 h. Another group of 6 animals was sham-exposed to room air and served as control. No mortalities occurred throughout the duration of the study (14 days). After exposure 3 of 12 rats had dried red nasal discharge, 1 of 12 rats had slight salivation, and 1 of 12 rats had slight lacrimation. All abnormal signs in the dosed animals were cleared by day 2 post-exposure. One control rat exhibited dried red nasal discharge on days 10 and 11 post-exposure, but this sign was considered inconsequential to the study outcome. There were 7 control rats and 8 dosed rats without abnormalities at necropsy. Of the remainder, there was a greater incidence of focal lung discoloration in the controls than in the dosed rats, a comparable incidence of dilated renal pelvis, and one instance of a dosed rat having a broken upper incisor. None of theses observations was considered to be related to treatment with the test substance. The LC50was greater than 21000 mg/m³, corresponding to 4504 ppm (ExxonMobil Chemical, 1985a).

In two earlier studies, rats (6 males) were exposed for 4 h to 1850, 3100, 5750 and 10000 ppm and 1050, 2390, 4450 and 7140 ppm, respectively. In the first study, mortalities occurred at 5750 ppm (6/6) and higher. Exposure to lethal concentrations induced a rapid and dramatic response. Repeated episodes of violent epileptiform convulsions, interspersed with periods of running and jumping. Death occured within 17 minutes for all rats tested at the highest concentration. The lungs of animals which died during exposure showed hemorrhagic areas with gray spots on the surfaces. Severe lung congestion was an isolated finding and lung consolidation was seen infrequently. In general, the livers and kidneys were congested in these animals, but all other organs appeared normal. Animals surviving the 14-day observation period revealed little of interest at autopsy. In a few instances, hemorrhagic areas were noted on the lung surfaces and an occasionally darkened liver or kidney was seen. All other organs appeared normal. The LC50value was calculated to be 4240 ppm, corresponding to 17300 -22200 mg/m³. The range of LC50is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9 (ExxonMobil Chemical, 1962a).

In the second study, 3/6 and 6/6 animals died at 4450 and 7140 ppm, respectively. Animals exposed to lethal concentrations exhibited clonic convulsions, laboured respiration, ataxia, and prostration preterminally. At the highest concentration, all six rats died within 1 hour; animals which survived 4 hours of exposure to 4450 ppm had a bloody exudate around the eyes and nose at the end of the exposure period. The lungs of animals which died during exposure showed hemorrhagic areas with gray spots on the surfaces. Severe lung congestion was an isolated finding and lung consolidation was seen infrequently. In general, the livers and kidneys were congested in these animals, but all other organs appeared normal. Animals surviving the 14-day observation period revealed little of interest at autopsy. In a few instances, hemorrhagic areas were noted on the lung surfaces and an occasionally darkened liver or kidney was seen. All other organs appeared normal. The LC50value was 4450 ppm, corresponding to 18200 -23300 mg/m³. As mentioned above, the range of LC50 is due to unknown amounts of hydrocarbons in the test substance with chain lengths ranging from C7 to C9 (ExxonMobil Chemical, 1962b).

Two further studies were performed in guinea pigs and rats following non-guideline procedures. In each study, 5 animals were exposed to 9400 mg/m³ for 10 min every 30 min during 4 h, yielding a total of eight 10-min exposures. In both studies, none of the exposed guinea pigs or rats died during the exposures or during the 14-day post-observation period. No pathological, histopathological or behavioural effects were observed throughout the study. The LC50value in both guinea pigs and rats was greater than 9400 mg/m³ (ExxonMobil Chemical, 1972a,b).

 

Dermal

 

There are no data available on the acute dermal toxicity of Hydrocarbons, C6-C10 (even numbered), n-alkanes, isoalkanes, >5% n-hexane. However, there are reliable data available for another category member. Thus, read-across was conducted based on a category read across approach.

Hydrocarbons, C7-C9, n-alkanes, isoalkanes, cyclics were applied on the shaved backs of Charles River CD rats (2/sex/dose) at 1, 2, and 4 mL/kg bw (730, 1460, and 2920 mg/kg bw) for 24 hours in accordance with the method of Noakes and Sanderson, 1969 [Br. J Indust. Med 26:59-64] (similar to OECD 402). No deaths or clinical signs were observed. The LD50 was greater than 4 mL/kg bw, corresponding to 2920 mg/kg bw (Shell Chemicals, 1977a).

Justification for classification or non-classification

Based on a category read-across approach, the available data on the acute toxicity of Hydrocarbons, C6-C10 (even numbered), n-alkanes, isoalkanes, >5% n-hexane are conclusive but not sufficient for classification. However, acute exposure may result in non-lethal narcotic effects and hydrocarbons poses aspiration hazard.

CLP: Aspiration Toxicity Category 1, STOT Single Exposure Category 3 (narcosis)