OBJECTIVES: Benzene exposure is associated with multiple adverse health effects on the human's biological systems including its cardiac, pulmonary, respiratory, renal, liver, and other organs' function. The purpose of this study is to assess the adverse health effects of benzene exposure on the cardiac functions in subjects affected by a flaring incident at the British Petroleum (BP) refinery in Texas City, Texas, USA. MATERIAL AND METHODS: A total of 1790 evaluable subjects who were exposed to benzene were included in the study. Using the patients' medical charts, the authors analyzed the data on various heart rate parameters as well as on the pulmonary function, the serum levels of β(2)-microglobulin, and the amount of urinary excretion of phenol. RESULTS: Of the 1790 subjects, 1083 experienced some type of cardiac function abnormality as assed by electrocardiogram (EKG) testing following their exposure to benzene. Normal cardiac function was preserved in 707 subjects despite their exposure to benzene. Regardless of the changes in their overall cardiac function, most benzene exposed subjects experienced some changes in various heart rate parameters such as P wave duration, PR interval, PR segment, QRS duration, QT interval, QTC interval, P wave axis, QRS axis, and T wave axis. Similarly, alterations in their pulmonary function test (PFT), β(2)-microglobulin levels, and urinary excretion of phenol were observed in benzene exposed subjects regardless of the changes in cardiac function. Furthermore, the incidence of the abnormality of various heart rate parameters was found to be 2–10 fold higher in the benzene exposed subjects compared with the general population. CONCLUSIONS: Environmental benzene exposure from the BP flaring incident pose significant health risks including specific alteration in cardiac and pulmonary functions in those subjects exposed to benzene.