Benzene and Aplastic Anemia
Aplastic anemia is a condition where bone marrow does not produce sufficient new cells to replenish blood cells. The condition involves both aplasia and anemia. Typically, anemia refers to low red blood cell counts, but aplastic anemia patients have lower counts of all three blood cell types: red blood cells, white blood cells, and platelets, called pancytopenia. The risks associated with aplastic anemia are infection and bleeding, which can both be life-threatening.
According to the Agency for Toxic Substances & Disease Registry, a division of the Department of Health & Human Services, "Benzene-induced aplastic anemia is caused by chronic exposure at relatively high doses." Fatal aplastic anemia following benzene exposure was first reported in workers in the 19th century.
Muzaffer Aksoy, M.D. states in his article titled, "Benzene as a Leukemogenic and Carcinogenic Agent" Amer. J. Ind. Med. 8:9-20 (1985) "Although the use of benzene started around the second half of 19th century, the chronic toxic effect of this chemical agent was seriously considered only in 1897. That year, Santesson  described four fatal cases of aplastic anemia in a Swedish bicycle-tire factory. Following Santesson's description of four cases of aplastic anemia, numerous animal experiences unanimously confirmed this effect of benzene."
Even though it has been known to science for more than a century that benzene causes aplastic anemia, and the levels of benzene in the environment are regulated, people are still at risk of developing aplastic anemia from benzene exposure.