Requests from Center investigators for EAFC support are received by all three operating units and reviewed for appropriate and effective Core response. As needed, the three unit Directors collectively discuss received requests and decide on the most appropriate course of action. Initial services are provided free to Center investigators, including planning discussions and consultation, preparation/review of exposure sections in proposals, and preliminary analyses of collected samples to ensure adequate sensitivity. Funding support is required to provide services beyond these initial services, and may include direct support in the budget of an existing or proposed grant, negotiations of a fee-for-service, or investigator acceptance of established fees for needed analyses. The threshold for specific funding support is a few hundred dollars or a few hours of faculty time.