The first study of a large group of workers breathing air with very low levels of benzene suggests that the chemical may harm the bone marrow, the body’s main factory for blood cells, even in amounts below the threshold deemed safe under U.S. law.
The researchers said counts of certain protective white blood cells in 250 Chinese shoe factory workers exposed to small amounts of benzene — less than one part per million in the air — were 15 percent to 18 percent lower than counts in a similar group of 140 garment workers who were not exposed. The lower blood counts were not in a range deemed harmful, but independent experts said the findings strongly hinted that benzene was one of a small group of chemicals for which no safe threshold exists.