Work schedules other than 7 to 8 hr/day and 40 hr/week are being introduced in many industrial operations. Novel work schedules, such as four 10-hour workdays per week or three 12-hour workdays per week for three weeks followed by four 12-hour workdays for three weeks and several other plans are presently being used. The Threshold Limit Values (TLV) do not apply to such novel schedules. Modified occupational limits, which are calculable from the methods suggested in this report, estimate the needed reduction in the TLV to provide protection for exposed workers. A simple system is suggested, but should be cautiously applied with good medical surveillance. Industrial hygiene experience with novel work schedules will ultimately provide the real requirements for acceptable exposures under such work conditions.

Benzene is a major commodity chemical of great value to industry. It has long been recognized that overexposure to benzene could result in damage to the blood-forming organs of the body. More recently, it has become apparent that chronic high levels of exposure are associated with the development of leukemia. Animal experiments have also suggested that overexposure to benzene may result in certain reproductive risks.

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