Aerial spraying is common procedure at banana plantations in Costa Rica even though the plantations often are situated very close to villages. The fungicide Mancozeb, which is metabolized into the more toxic substance ETU, is one of the pesticides used in aerial sprayings. This thesis has evaluated the exposure of ETU to children living in one of these villages and compared that exposure to different reference doses, of which one was set with a probabilistic approach in this thesis. The exposure doses exceed some of the reference doses and all children have an unacceptable high cancer risk. The main factor that induces high exposure appears to be aerial sprayings close to the village, where Mancozeb and ETU drift into the village. Proposed actions to reduce exposure should be taken at different levels, for example can legislation, timing of aerial spraying activities, education of local health representatives and the searching for alternatives be parallel treatment processes.