The exposure scenario in this slide attempts to represent the multiple exposure pathways via multiple media for a child spending some time at a playground treated with a wood preservative (e.g., arsenate). For a complete assessment of the child's daily exposure to the wood preservative, which is assumed to be ubiquitous in the environment, it is necessary to consider the four common routes of exposure mentioned in the last (and this) slide.

The child could be exposed to the wood preservative residues through dermal contact with the contaminated soil around the playground structure. The child's skin could also come into contact with the residues left on the treated playground structures, or potentially even with indoor surface residues which have been translocated through contaminated outdoor air. Another potential source of dermal uptake is through contaminated shower or bath water.

The indoor and outdoor ambient air can be potential sources for inhalation exposure. The child also could inhale the residues in the shower or bath water contaminated with the chemical originated from another source.

In addition to drinking water and food, the child could ingest the residues on playground structures or soil through hand-to-mouth exposure.

It is important to note that in performing a human exposure assessment as part of a health risk assessment, the background level from sources other than the treated site is also critical. This is because the adverse effect, if any, is induced by the total (effective) amount of the chemical in the human body.