Arsenic in urban/historic fill soil, originating from both natural and anthropogenic sources, is a continuing concern from a human health risk point of view. This concern is heightened in urban gardens where the soil is to be used for growing vegetables for consumption.

The presentation explores the origin of arsenic present in New England urban/historic fill soil and will derive an understanding of the relative contribution of the natural and anthropogenic components using available data sets. These data sets include more than 5,000 urban soil samples from the Central Artery/Tunnel Project in Boston statistically analyzed using ProUCL 4.0. Data also includes more than 2,700 samples of a natural/rural background data set from a comprehensive study of rock and stream sediment arsenic in New England analyzed by the U.S. Geological Survey (USGS), supported by other available data sets resulting in a broad base of up to approximately 10,000 individual sample results. These multiple data sets will be reviewed and summarized such that there are a mean/median and upper values presented for natural soils and rocks and a mean/median and upper values presented for anthropogenic impacted soils, with and without outliers. From this compilation will be derived an understanding of the numerical differential between them. Finally, we will apply standard human health risk calculations, provided by the Massachusetts Department of Environmental Protection (MassDEP), to illustrate the magnitude of potential effects of the natural soil and the anthropogenic–containing soil. The derived mean, median, and upper percentage values will be considered in the context of the human health risk assessment calculations. In conclusion, the exercise will identify the risk significance of the anthropogenic contribution relative to the natural soil and provide an understanding of the overall affect associated with background in the urban environment.