Overview of benzene‐induced aplastic anaemia

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Abstract
Abstract:  The scientific literature is replete with reports of cases of benzene‐induced toxicity to the haematopoietic system. These mainly involve aplastic anaemia, the first cases of which were reported in 1897. At high levels of benzene exposure (air concentration > 100 p.p.m.), the incidence of aplastic anaemia is approximately 1/100 individuals exposed, but this drops precipitously at lower levels of exposure (10–20 p.p.m.) to around 1/10,000. Factors that affect susceptibility may include high liver cytochrome P450 2E1 activity and low folic acid intake. The mechanism of benzene‐induced aplastic anaemia remains unclear, but is likely to involve: (a) metabolism of benzene in the liver; (b) transport of metabolites to the marrow and their secondary activation to toxic quinones and free radicals by peroxidase enzymes; (c) induction of apoptosis, DNA damage and altered differentiation in early progenitor cells; and (d) depletion of the stem cell pool.