[en] The monitoring program at the Middlesex Sampling Plant (MSP) and Middlesex Municipal Landfill (MML) measures radon gas concentrations in air; external gamma radiation levels; and uranium and radium concentrations in surface water, groundwater, and sediment. To verify that the sites are in compliance with the DOE radiation protection standard (100 mrem/yr) and to assess their potential effect on public health, the radiation dose was calculated for the maximally exposed individual. Based on the conservative scenarios described in the report, this individual, at the MSP, would receive an annual external exposure approximately equivalent to 10 percent of the DOE radiation protection standard. By comparison, the incremental dose received from living in a brick house as opposed to a wooden house is about the same. At the MML, the annual external exposure to the maximally exposed individual would be less than 1 percent of the standard. The cumulative dose to the population within an 80-km (50-mi) radius of the sites that would result from radioactive materials present at the MSP and MML would be indistinguishable from the dose that the same population would receive from naturally occurring radioactive sources. Results of the 1987 monitoring show that the MSP and MML are in compliance with the DOE radiation protection standard. 14 refs., 11 figs., 22 tabs