Spinetta Marengo (Solvay, now Syensqo, chemical plant)

The chemical complex dates from 1905, when the Società di Marengo began making copper sulphate. It passed to Montecatini in 1933, became Montedison from 1966, and joined the Solvay group in 2002; the operating company, Solvay Specialty Polymers Italy, is now part of the Syensqo group.

Production of tetrafluoroethylene and PTFE began in 1960. PFOA was used as the polymerisation surfactant from 1960 to mid-2013. ADV, a mixture of chlorinated perfluoropolyether carboxylic acids, has been made at the plant since the 1990s and used since 1996; cC6O4, introduced as a replacement for PFOA, has been in use since 2012. Trichloroethylene has also been used in large quantities since the end of 2004.

Biological monitoring of the workers began in 2004 for PFOA, in 2011 for ADV and in 2013 for cC6O4. In the plant, median serum PFOA fell from 1,900 µg/l in 2004 to 14 µg/l in 2021; median ADV from 434 to 86 µg/l between 2011 and 2021.

Outside the plant, a water sample from the Bormida taken near the works contained legacy and emerging PFAS (a 2024 study, which cites ARPA Piemonte's checks). In 2008 the discovery of hexavalent chromium in groundwater opened criminal proceedings; in December 2019 the Court of Cassation upheld the convictions of three former managers for environmental disaster, with suspended sentences of one year and eight months (Domani, 2020). ARPA checks in December 2021–March 2022, reported by the local press, found PFOA, ADV and cC6O4, chloroform, carbon tetrachloride, hexavalent chromium and fluoride in groundwater, including downstream of the hydraulic barrier. Biomonitoring of residents is not documented in this record.