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Adherence and adsorption: Describes contaminants present on plant sufaces which contribute to incidental ingestion (defined below). Contaminants in the soil can come into contact with plant surfaces. Soil can adhere to the surface (think of soil-covered carrots). Contaminants can be consumed with soil adhered to fruits and vegetables but can largely be removed with washing. Contaminants in soil can also adsorp, or bind, to plant surfaces. Contaminants adsorbed to fruit and vegetable surfaces are difficult to remove with washing.

Bioavailable: the fraction of a contaminant that can pass through a tissue barrier (such as lung tissue, intestinal tract, or skin) into the bloodstream. 

Contaminated soil: Soil with contaminant concentration that is sufficiently high to harm human health.

Dose: The amount of lead from the environment that enters the bloodstream (see Risk and Contaminated Soil)

Exposure pathway: the ways by which a person comes into contact with a contaminant. Specific exposures pathways can be grouped into three basic categories: inhalation, ingestion, and skin contact.

Heavy metal: a metal element with relatively high density or atomic weight. Frequently used to refer to such elements that are toxic, including cadmium, lead, and mercury. 

Incidental ingestion: unintentional soil ingestion from swallowing dust, consuming soiled produce with adhered or adsorbed soil contaminants (defined above), or hand-to-mouth transfer. Incidental ingestion is a major exposure pathway for children and adults.

Metalloid: an element with properties of both a metal and nonmetal. Arsenic, a common soil pollutant, is a metalloid. 

Plant uptake: also known as plant root uptake, occurs when a plant takes up soil contaminants through their roots and it becomes part of the plant tissues (roots, shoots, and fruits). (This website distinguishes plant root uptake from contaminant adherence and adbsorption (defined above) because different management practices are needed to reduce plant root uptake and contaminant adherence and adsorption. Note that other resources may consider plant uptake to be both contaminant adherence and adsorption and plant root uptake.)

Pica: a condition where an individual intentionally consumes nonfood objects. More common in children than adults. Some children with pica intentionally consume soil.

Polluted soil: Soil with contaminant concentration above background level. Polluted soils may or may not pose a risk to human health.

Soil ingestion: when soil enters the body through the intestinal tract. This occurs with direct ingestion (chid eating soil), incidental ingestion (consuming soil on soiled food or hands), and swallowing dust filtered out of the respiratory tract.