Pesticides, pharmaceuticals and industrial chemicals found everywhere in seawaterhttps://www.lemonde.fr/en/environment/article/2026/03/22/pesticides-pharmaceuticals-and-industrial-chemicals-found-everywhere-in-seawater_6751696_114.htmlThe researchers detected a total of 248 human-made compounds in the waters of the Pacific, North Atlantic and Indian oceans, which, across all the samples analyzed, made up a median of 2% of dissolved organic matter. Among these were pesticides such as DEET and icaridin (both insect repellents), additives used in plastics such as phthalates, UV filters from cosmetics, surfactants and a whole range of pharmaceutical residues, including beta-blockers, antidepressants and anti-infectives such as chloroquine.
The analyses also revealed that levels of chemical pollution were particularly high near coastlines, with a median proportion of contaminants from human activity amounting to 20% of all dissolved organic matter, and reaching as much as 63% in the most extreme cases.
"I was quite shocked when we first saw the results. (...) When you think about it from a hydrological perspective, I think this also makes complete sense," noted Petras. "In Germany, for example, during the summer months, a large portion of water contribution to the major rivers comes from wastewater treatment plants. Those can currently not remove all/most of the organic compounds, so they will end up in the river and then in the ocean."
Marine waters contain "about 700 billion metric tons of dissolved organic carbon – a mix of proteins, carbohydrates, lipids and other molecules – mainly from the biological activity of marine organisms and river inputs," explained Sempéré. The fact that human-made molecules in the ocean account for 2% of the chemical signal is, in his view, "far from negligible," and a figure of 20% in coastal areas "is huge."
Widespread presence of anthropogenic compounds in marine dissolved organic matter | Nature Geosciencehttps://www.nature.com/articles/s41561-026-01928-z