2.11 SWIMMING DERMAL CONTACT


    Individuals swimming will be exposed to contaminated water via the dermal absorption pathway from contact with water. The following considerations are given to estimate the dermal contact exposure to surface water while swimming.
Transport Medium:
surface water concentration in the water body used for swimming, Cswi, pCi/L or mg/L, expressed as a 70-year average value
Special Process:
loss of pollutants during transport in the surface water body by volatilization or decay absorption through the skin during a swimming event
Exposure Factors:
area of skin exposed, swimming frequency, swimming event time, and exposure duration.


    The loss of pollutants during transport in the surface water body is evaluated using Equation (3). The swimming frequency and time period of each swimming event determine the average time spent swimming per day. The swimming event time and absorption parameters for each pollutant are used to estimate the amount of a pollutant absorbed through the skin during each swimming event. This calculation is performed using the same dermal absorption model described for the shower dermal absorption exposure pathway in Subsection 2.2.

    For inorganic chemicals and radionuclides, the intake per swimming event per unit area of skin contacted is evaluated as follows:

(72)


where

    For organic pollutants, the absorption per event is evaluated using the six-step process described in Subsection 2.2 by Equations (5) through (12). These equations give the amount of a pollutant absorbed per unit area of skin contacted during one swimming event of duration TEw. In performing the evaluation for swimming exposures, the swimming event time is used in place of the showering event time, TEs.

    The average daily dose from chemical pollutants for the swimming dermal contact exposure pathway is evaluated as follows, with correction for the gastrointestinal tract absorption fraction:

(73)



where

    The average daily dose as computed by Equation (73) is equivalent to oral exposure because the GI absorption correction has been applied. The averaging time for noncarcinogenic chemicals is set to the exposure duration, and the averaging time for carcinogenic chemicals is fixed at 70 years. The equation is used for all pollutants except radionuclides. For radionuclides, the GI absorption fraction and body weight are not applied because radionuclide specific dose conversion factors for dermal intake are provided in the chemical database for the 70-kg reference man. The equation for radionuclides is as follows:

(74)



where

and other terms are as previously defined.