Field studies have been done with the herbicide, fluazifop-butyl, to assess exposure and systemic absorption following application by backpack and vehicle sprayers. The data have been used to assess the usefulness of a model for predicting the systemic absorption of a pesticide. The model uses the concept of the 'rate of absorption' through skin and this model is compared with the 'percent absorption' concept in their ability to predict systemic absorption following application with vehicle sprayers. The field study of vehicle sprayers showed that the 'rate of absorption' model was a better predictor of systemic absorption.