Draft document with asbestos data tables, DEP Box 09

NYC 9/11 Public Portal Document

I » DRAFT applying a factor of 140 m^/50 m^, accounting for the difference between weekly ventilation rates associated with continuous exposure and occupational exposure.

Risk Characterization The risk characterization combines the previously described components of the Risk Assessment (i.e., hazard identification, exposure assessment, and toxicity assessment) to provide numerical estimates of human health risk. In general, these risk estimates are expressed in terms of excess lifetime cancer risk for cancer endpoints expressed as a probability. The EPA has established a range of acceptable risk from one in ten thousand to a one in one million. A result below one in one million is generally accepted to represent no significant risk of adverse health effects. A result above one in ten thousand generally warrants aggressive risk management actions. A result between one in one million and one in ten thousand represents a ‘gray area’ where the costs of risk reduction need to be carefully weighed with the projected benefits.

Table 2 presents the estimated total cancer risks for the Commuter receptor scenario for exposure to asbestos in air. The Two-hour Commuter is shown to have a cancer risk of eight in one million (0.000008). The one-hour and one-half hour Commuter are shown to have cancer risks of four in one million (0.000004) and two in one million (0.000002), respectively.

Risk-based Concentrations Risk-based concentrations have been developed for asbestos in air by running the exposure assessment equations presented above in reverse. These risk-based concentrations are based on the inhalation of airborne asbestos fibers and are specific to the Commuter scenario developed in the exposure assessment. Table 3 presents risk­ based concentrations at target risk levels of one in ten thousand (lE-4), one in one hundred thousand (lE-5), and one in one million (lE-6). The following equations was used to calculate risk-based concentrations:

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