Dermal Contact

Adherence factor

The adherence factor is a measure of the tendency for soil to adhere to skin. The data necessary to estimate the dermal adherence factor for wildlife are generally limited or not available. Therefore, a conservative human health value of 1 mg/cm² (0.000001 kg/cm²) is set as the default for the species provided in SADA (EPA 1992). This value is based on results for laboratory rodents and was developed by shaving the fur and applying the contaminant directly to the exposed skin. However, feathers of birds, fur on mammals, and scales on reptiles are believed to reduce dermal exposure by limiting the contact of the skin surface with the contaminated media (EPA 2000). The user can customize these values if guidance or data is available.

Surface area

Defaults for wildlife receptor surface area (cm²) are based on published studies or modeled based on default body weight using allometric equations for birds or mammals in EPA (1993) Wildlife Exposure Factors Handbook.