 Microplastic contamination has been detected in both sediments and floating at the surface of the northwest European region. The concentration of microplastics in sediments ranges from 0 to 3,146 particles per kilogram of dry weight sediment, while floating concentrations range from 0 to 1.5 particles per cubic meter. Larger samples and greater volumes of water are needed to detect detectable concentrations of microplastics at the surface. Confidence intervals for different sample sizes indicate that larger sample sizes and volumes of water are needed to accurately measure microplastic concentrations at the surface. Areas with higher organic carbon content and estuaries appear to be hotspots for microplastic contamination. It is important to standardize monitoring methods across marine regions so that comparisons can be made over time. This article was authored by Thomas Meis, Thomas Meis, Myra D. van der Mulen, and others.