Unexpected events are also an important source of surface contamination for applicators and the exposure levels associated with these events can result in acute and long-term health effects. Such events include spills and splashes that may lead to high personal exposure and can overwhelm usual protective measures. In the Agricultural Health Study (USA) 14% of farmers licensed to apply restricted pesticides reported ever having had such an exposure event. The unexpected problems that lead to high exposure events are most common during mixing/loading and application phases but may also occur during clean-up.