The odour threshold is 12 ppm. The odour serves only as a warning of exposure. If you are handling benzene without smelling it, this does not mean that there is no exposure. Health effects Benzene enters the body through inhalation and it may pass through the skin. Exposure to low concentrations of benzene vapour or to the liquid which has penetrated the skin may cause dizziness, lightheadedness, headache, loss of appetite and stomach upset.
Exposure can also irritate the nose and throat.
High exposures to benzene may cause irregularities in the heart beat which can lead to death. Repeated exposure can damage the bone marrow, which is the blood-forming organ, causing a condition called aplastic anaemia. This may also lead to death. There is sufficient evidence that benzene causes leukaemia in exposed workers. Many scientists say that there is no safe level of exposure to a carcinogen.