Carbon-14 has been measured in natural, biological materials growing in the vicinity of Sellafield, Cumbria, as a continuing project with British Nuclear Fuels Ltd. to understand the dispersion of releases from the site over several seasons. Reports measurement of locally grown foodstuffs for monitoring purposes, individual tree rings to establish a chronology of releases, hawthorn berries for spatial investigations, and controlled plot uptake experiments. In attempting to validate a current dispersion model (Clarke 1979) over a six-year period, general agreement in most years has been observed. Certain anomalies, which probably relate to topographical features, are, however, leading to more detailed correlation with local meteorological data.