Pollution status of marine protected areas worldwide and the consequent toxic effects are unknown.

Chemical pollution is considered a factor that may threaten marine protected areas (MPAs), and recent studies have found contamination and associated biological effects in some MPAs. However, organized data on this topic are lacking. This study reviewed the literature on pollution in MPAs in order to compile data, determine whether MPAs are influenced by pollution and, whenever possible, describe how they are being affected by contaminants. The results show that the pollution status is unknown in most MPAs worldwide. When any information is available, it is often insufficient to diagnose the threats to biodiversity or to support further actions. More robust and extensive information is available on a small number of MPAs, and much less information is available regarding the negative effects of pollution. More than 80% of the areas studied exhibited evidence of contamination at potentially toxic concentrations or were found to have a status that produced toxic effects on the biota. The scientific community is encouraged to study pollution in MPAs worldwide.