The number of swimming pools and spas worldwide is in the millions. According to the estimation by the U.S. EPA (Dang, 1996), these pools and spas contain nearly 15 billion gallons of water that need to be treated with one or more water disinfectants.

In addition to drinking water or other sources as a potential, people can be exposed to the water disinfectants from being in or at these pools and spas. Although somewhat exaggerated by the U.S. EPA, the possible routes of swimmer exposure that can be considered are characterized in their assessment model developed specifically for this type of exposure potential. In their model, known as the Swimmer Exposure Assessment Model (SWIMODEL), the U.S. EPA provided algorithms for calculating the exposures from 7 potential routes of entry for swimmers in or at pools and spas treated with water disinfectants (Dang, 1996).

The 7 routes of entry are: (1) the greater skin surface proper; (2) oral/drinking of pool water; (3) inhalation at the pool; (4) the buccal/sublingual area; (5) the orbital/nasal area; (6) the aural area; and (7) the sexual organ area. Upon a careful review of the parameters involved, Dong and Ross (in press) denounced the significance of the last four routes. Yet despite such a denouncement, at times the dermal uptakes via the last four routes can be as potential as the oral intakes from food and drinking water, or as the inhalation of ambient air away from the pool.