Investors are stepping up pressure on companies to end the production and use of hazardous “forever chemicals” amid concerns over increasing litigation and regulatory scrutiny.

More than 50 investment firms representing $10tn in assets will write on Wednesday to the world’s biggest producers of perfluoroalkyl and polyfluoroalkyl substances, known as PFAS, to demand a “time-bound phaseout plan”, increased transparency on production and greater investment in safer alternatives. 

“Manufacturers and users of PFAS chemicals are exposed to deep liability and insurance risks, reminiscent of those historically linked to asbestos,” the letter states. This “could materially adversely harm the long-term value of companies involved in their manufacture and sale”, the investors say.