Biological and ambient monitoring of benzene in the workplace.

Surveillance of workers potentially exposed to benzene is focused on detecting evidence of bone marrow toxicity. A particularly thorough hematological evaluation should be conducted upon entrance to the work force at risk. This should be followed by semiannual surveillance using the routine complete blood count as the major monitoring technique. Attention should also be placed on increases in the mean corpuscular volume and decreases in the lymphocyte count as possible early indicators of benzene toxicity. Other hematological findings that may indicate early benzene toxicity depend upon alterations in the characteristics of blood cells, eg, a prolongation of the red cell glycerol hemolysis time, need to be more fully evaluated. No single finding or constellation of findings is pathognomonic of benzene hematotoxicity, and all findings must be carefully interpreted in terms of the individual or group at risk.