Over the last few years leaded petrols have been phased out of use. However this has resulted in higher levels of benzene and other aromatics in the substitute unleaded petrol. Benzene breaks down quickly in the environment and is not stored in the tissues of plants or animals. However, it is still hazardous to humans at high levels as it can cause several diseases of the blood including leukemia (cancer of the white blood cells). Benzene monitoring programmes were started in New Zealand in 1994 and are continuing because the levels in some locations were found.
