Estimated Quantities and Trends of Cadmium, Lead, and Mercury in US Municipal Solid Waste Based on Analysis of Incinerator Ash

Heavy metals are present in a variety of products and can be released to the environment during product life cycles. The concentration of metals in municipal solid waste (MSW) reflects the amount of metals in products and is directly related to the amount of metals transferred to disposal sites. Measured monthly mean concentrations of cadmium, lead, and mercury in the ash from May 1995 through October 2007 at the Essex County, NJ incinerator and from May 2004 through November 2007 at the Warren County, NJ incinerator were used, along with air emissions data for mercury, to estimate the content of these metals in MSW. Estimated mean concentration and 95% confidence limits for cadmium in MSW at the Essex and Warren facilities, respectively, were 17.4 +/- 0.1 and 10.1 +/- 1.2 ppm. For lead, the corresponding values were 408 +/- 41 and 239 +/- 42 ppm, and for mercury, they were 2.6 +/- 0.2 and 0.9 +/- 0.2 ppm. A trend of increasing cadmium concentrations was found at both facilities. No change vs. time was observed in lead concentrations. Mercury concentration was found to be decreasing over time at the Essex facility.