GeoInsighter Summer/Fall 2007 Newsletter

MCP ALERT!

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Modifications to last year's "Wave 2" changes in the Massachusetts Contingency Plan resulted in some significant changes in evaluating risks at sites with impacts from a selected group of metals (arsenic, cadmium, chromium III, chromium IV, lead, nickel, and zinc), chlordane (a pesticide), and polychlorinated biphenyls (PCBs). The Massachusetts Department of Environmental Protection is now considering the potential human health risk associated with eating fruits and vegetables grown in soils with these constituents. These new plant uptake factors have had a substantial effect in evaluating potential risks posed by impacted soil, such that the new risk-based soil concentrations are generally much lower than the published Method 1 Risk Characterization standards and sometimes even below typical laboratory method detection limits.

The net result is that, if risks for these constituents are characterized using a Method 3 Risk Characterization, then a deed restriction, in the form of an Activity and Use Limitation, will often be required to restrict growing fruits and vegetables at a property. Alternative strategies that may be available at some sites are to conduct a Method 1 Risk Characterization or a study to evaluate potential background concentrations of these constituents at a site (note that a background evaluation may not be applicable for chlordane and PCBs).