For dermal exposure of swimmers to a water disinfectant or the kind, the basic calculation algorithm used in U.S. EPA's SWIMODEL (Dang, 1996) is: [dermal uptake] = [water concentration] x [hourly permeability coefficient] x [surface area of exposed skin] x [exposure duration]. Five body regions were considered in SWIMODEL in calculating the total dermal dose: (a) the greater skin surface proper; (b) the buccal/sublingual area; (c) the orbital/nasal area; (d) the aural area; and (e) the sexual organ area. However, the dermal doses to be received from the last four minor epidermal areas are often ignored as they would amount to very little compared to that from the greater skin surface proper (see Dong and Ross, in press).

Dermal permeability coefficient (typically in cm/hr) is chemical-specific. As discussed in Slide 8, this permeability is likely to vary with anatomic region and water concentration. Dermal coefficient values have been estimated by U.S. EPA (1992) for a long list of chemicals without the consideration of anatomic or dose variation. It is important to note that the dermal exposure calculated here is an absorbed dose, not an applied dose, since it is based on the use of a dermal permeability coefficient.

The concentration of the disinfectant in the pool water can be estimated from treatment rate or volume. Its air level at the pool can be approximated from water concentration using Rault's law for vapor pressure depression. The calculations of the doses, if any significant, from drinking water, ambient air, and dietary intake are essentially the same as those discussed in the last case.