Hexane is reported to be three times more acutely toxic to mice than pentane. Concentrations of 30,000 ppm produce central nervous system (CNS) depression within 30-60 minutes. Concentrations ranging from 35,000 to 40,000 ppm can cause convulsions and death. When mice were exposed to air containing 2.5-3% hexane sds for 4 days, liver enlargement was observed after 24 hours. In another study, mice were exposed to commercial hexane (65-70% n-hexane) 24 hours a day, 6 days a week for one year. Exposure levels range from 100 to 2000 ppm. Animals exposed to 1000 and 2000 ppm n-hexane exhibit atrophy and degeneration of hind leg muscle fibers
Toxicology and Metabolism
Both n-hexane and MnBK are colorless liquids and almost insoluble in water. Their common neurotoxic metabolite 2,5-HD is highly water soluble. Therefore, 2,5-HD is widely used as the most convenient compound for experimental studies of six-carbon neuropathy. MnBK is easily absorbed through the skin and respiratory tract. Skin absorption of n-hexane may be the primary route of entry into the human body, but appropriate experimental studies have not been performed to confirm this. Hexane is more difficult to absorb through the respiratory tract than MnBK.
The metabolism of n-hexane and MnBK has been determined in experimental animals and humans. n-Hexane can be oxidized to form 2-hexanol, which can be metabolized to 2,5-hexanediol or MnBK, both of which can be converted to 5-hydroxy-2-hexanone and then to 2,5-HD . MnBK also produces 2,5-HD in the body. Studies of MnBK and n-hexane metabolism have identified 2,5-HD as the most persistent neurotoxic metabolite of both substances.
Removal of hydrocarbons of mineral origin
Hexane (C6) is partially removed by the vacuum system by neutralization and/or bleaching, while the remainder is removed in the deodorizer to levels below the detection limit (0.1 mg kg−1).
Gasoline has never been detected as a chemical hazard in crude oil and fats. Therefore, the refining process has never been proven to remove gasoline. However, experience with compounds of similar or even lower volatility shows that they can be completely removed during deodorization.
The upper limit of mineral oil middle distillates (C10-C24, including kerosene and diesel) in crude palm oil is 25 mg kg−1. Process validation showed that this level could be reduced below the detection limit (10 mg kg−1).
Mineral oil fractions with carbon atoms higher than C24 are difficult to remove during the refining process. The physical and chemical properties of these components are not sufficiently different from those of edible oils and fats for separation.
