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Two key 30 day subcutaneous exposure study (Khedun, 1996; Klimisch score =2 and Maharaj, 1982; Klimisch score =2) and one key 90 day subcutaneous exposure study (Khedun, 1992; Klimisch score =2) were identified for n-hexane.

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In a key 30 day cardiotoxic effects of n-hexane was determined (Khedun, 1996; Klimisch score =2). Groups of 15 rats were administered 0.1 ml of test substance in olive oil (1:1 v/v) subcutaneously for 30 days. After the exposure, the animals were sacrificed. The hearts of one group were used to determine the effect of exposure of test substance on the ventricular fibrillation threshold (VFT). The other group was used to determine effect of exposure on magnesium and potassium levels. Another group of rats was given the same exposure, but with supplemental magnesium or potassium in the diet as well. The hearts of these animals were also examined using light and electron microscopy. There was a significant reduction in VFT and myocardial magnesium and potassium levels in all exposure groups. Histopathological changes were seen in heart tissue of exposure groups when examined with an electron microscope. Exposure to 0.1 ml of n-hexane for 30 days subcutaneously resulted in decreased VFT even when supplemental magnesium and potassium was given in the diet.

In a key subcutaneous exposure study the cardiotoxic effects of 90 days exposure to hexane on rats was examined (Khedun, 1992; Klimisch score =2). Groups of 20 rats were administered 0.1 ml of test substance subcutaneously for 90 days. After the exposure period, the hearts of one-half of the exposure animals were examined for coronary flow, heart rate, and ventricular fibrillation threshold (VFT). The hearts of the other exposure animals were examined for magnesium, potassium, and zinc levels. The VFT and magnesium, potassium, and zinc levels were significantly reduced in exposure groups as compared to controls.

In a key subcutaneous 30 day study the cardiotoxic effects of hexane exposure to rats were examined (Maharaj, 1982; Klimisch score =2). 10 rats were exposed to 0.1 ml of test substance subcutaneously for 30 days. At the end of the exposure period, the animals were sacrificed, and their heart tissue examined via light microscopy and TEM. The morphometry of the cardiac tissue was also examined. The exposure did not cause chronic myofiber pathology. However, ultrastructural changes were noted in the mitochondria and myofibrils that mimic myocardial ischaemia. These changes could lead to myocardial failure.