Pollutants enter the marine food chain through rain and rivers that wash them away from the land into the ocean. They also enter through direct dumping or leakage from ships, pipelines, or offshore platforms. Pollutants spread in the marine food chain through bioaccumulation and biomagnification. Bioaccumulation is the process by which toxins accumulate in living organisms. Biomagnification is the process by which toxins increase in concentration as they move up the food chain.