Determining standards for professional divers diving in benzene polluted waters

The main objective of this study is to calculate the hours of diving in benzene-polluted waters acceptable for professional divers. We considered recommended absorption limit as that from pulmonary workplace absorption during an 8-h workday at recommended exposure limits set by the National Institute of Occupational Safety and Health, and developed a formula to determine recommended limits for diving time based on actual water and sediment concentrations and exposure conditions. The recommended absorption limit is 1.6 mg of benzene per workday. This is equivalent to total body dermal absorption over a 1-h dive at water concentration of 7.6 mg/L, or absorption from drinking 0.1 L of water with a concentration of 16.5 mg/L, or dermal absorption with 50% of the body covered in sediment with a concentration of 18,851 mg/kg. A formula that calculates allowable diving time considering benzene water and sediment concentrations, and gastrointestinal and dermal exposures is presented. Water concentrations and not exposure to sediment limit recommended diving time, and unlimited diving in areas with sediment and water concentrations thought to pose a serious human health hazard would not surpass the recommended amount of benzene absorbed in the workplace. We conclude that allowable diving time in polluted waters can be calculated resulting in absorption equivalent to recommended limits for pulmonary absorption in the workplace. Our results suggest that agencies determining significant health risk levels of chemical concentrations in sediment and water should consider our findings.