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risk values approved by either the U.S. Environmental Protec- <br /> tion Agency (EPA) or the California Department of Health <br /> Services (DHS) . (The SJCAPCD has approved the use of a 30-year <br /> exposure scenario in calculating cancer health risks.) The <br /> cancer risk analysis must also include an evaluation of nonin- <br /> halation pathway exposure. Noninhalation pathway exposure <br /> occurs when air emissions contaminate foods or breast milk, or <br /> become absorbed through the skin. The noninhalation pathways <br /> examined in this study were crop, soil , meat, and milk inges- <br /> tion, dermal (i .e. , skin) absorption, and breast milk contami- <br /> nation. The sum of inhalation and noninhalation health risks <br /> must be less than one in one million (i .e, one case of cancer <br /> in an exposed population of one million) . However, if the air <br /> emission source is equipped with the best available air emis- <br /> sion control technology, the health risks may be as high as <br /> five in one million. <br /> • Cancer burden analysis. This analysis indicates the number of <br /> excess cancer cases which would be expected from population <br /> exposure to project emissions. The SJCAPCD considers an <br /> acceptable cancer burden to be less than 1.0 case in the <br /> exposed population. <br /> • Acute effects analysis. Short-term, noncarcinogenic exposure <br /> is to be assessed by comparing contaminant concentration levels <br /> with known acceptable exposure levels. The SJCAPCD requires <br /> that contaminant concentrations be at or below the acceptable <br /> levels for acute effects. <br /> Existing Air Ouality <br /> To assess current air quality levels in the vicinity of the project <br /> site, data collected and compiled by the California Air Resources Board <br /> (ARB) were examined. Data collected in Stockton in 1984, 1985, and 1986 <br /> were determined to be most representative of the project site and are <br /> presented in Table 3.8 along with applicable state and federal air qual- <br /> ity limits. Ambient air quality data and associated limits are only <br /> available for the so-called "criteria" pollutants listed in Table 3.8. <br /> 3-56 <br /> 101-30.R5 4/13/89 <br />