Every summer for more than 30 years, massive quantities of green algae have been washing up on parts of the French coastline. Once washed up on beaches, these algae deposits decompose and produce large quantities of gases, especially hydrogen sulfide (H2S), potentially exposing walkers, local residents and workers required to collect these algae, to risks. The issue of the risks associated with these algae when bathing or consuming shellfish, is also raised. Below are details of the Agency’s work on this topic.

Every summer for more than 30 years, massive quantities of green algae have been washing up on parts of the French coastline. Once washed up on beaches, these algae deposits decompose and produce large quantities of gases, especially hydrogen sulfide (H2S), potentially exposing walkers, local residents, workers required to collect these algae and animals in the vicinity, to risks. In July 2011, the discovery of wild animal carcasses in the Gouessant estuary led the French Ministry of Agriculture to make a formal request to ANSES to establish the cause of death and the possible existence of a link between H2S fumes at the site and the deaths of these animals. Below are details of the Agency's work on this subject.