The US NGO Healthy Building Network (HBN) has warned that the continued use of mercury and asbestos in the supply chain of polyvinyl chloride (PVC), and other chlorine-based products, is a source of environmental pollution.
The NGO surveyed the 86 largest chlor-alkali and 56 largest PVC plants in the Americas, Europe and Africa. They found that 32 chlor-alkali plants still use mercury cell and/or asbestos diaphragm technologies to produce chlorine. The others employ more modern methods, using diaphragms or membranes coated with per- and polyfluoroalkyl substances (PFASs).
Chlorine-based production is responsible for some 300 tons of asbestos waste a year in the US, the NGO warned. And in a plant in Poland, for example, concentrations of asbestos in the workspace air "routinely exceeded up to 30 times the occupational exposure limits".
Meanwhile, two mercury-cell plants in the US have released over 23.8 metric tons of mercury into the air since 1987, HBN said. And another has released "at least" 715kg of the chemical into the Ohio River.
It further warned that releases of PFASs – the only alternatives to mercury and asbestos cells in chlor-alkali plants worldwide – are undocumented. HBN said this is concerning because the chemicals are toxic at low doses and persist in the environment.
The NGO said it hopes the report will help manufacturers avoid chemicals derived from "toxic technologies" and help scientists to better understand the material flow of the pollutants generated by PVC production.
Chlorine-based plastics production is driven by demand from the building industry, where PVC is widely used in products such as pipes, flooring and adhesives.
Shift from asbestos and mercury
Most chlorine produced in Europe and Africa comes from PFAS-coated membrane technology, HBN reported, but the largest chlor-alkali plant in Europe – DowDuPont's complex in Stade, Germany – relies on asbestos diaphragms. Mercury cells are in use at two German chlor-alkali plants run by BASF and Evonik.
DowDuPont is converting plants using diaphragm technology to non-asbestos operations, in alignment with regional regulatory requirements. Meanwhile, DowDuPont said: "It is important to note that no asbestos is transferred to the chlorine during production".
BASF has one remaining plant using the mercury-cell process, but it will be replaced with a PFAS-membrane plant. The chemical giant said it is reducing mercury emissions to a minimum and "will eliminate it from the production of chlor-alkali by start-up of the membrane process".
Asbestos in the US
While Europe is phasing out use of the chemical, asbestos diaphragms still account for 45% of chlorine-production capacity in the US, according to HBN. Most of this centres on the US Gulf Coast, the world’s lowest-cost region for production of chlorine, and home to nine facilities that use asbestos technology.
The US imports 480 tons of asbestos a year on average for 11 chlor-alkali plants, the NGO said. Most of this comes from mines in Brazil, but the country has banned production of the chemical and exports will soon cease. When they do, the use of asbestos in the US is likely to become dependent on a mine in Russia.
The American Chemistry Council’s (ACC's) chlor-alkali division declined to comment on how this might affect asbestos-chlorine production in the US, but said facilities that use asbestos during chlorine production "adhere to established safety protocols to minimise potential asbestos exposure to workers, the public and the environment".
The ACC said it will continue to work with the US EPA "to ensure risk evaluation of asbestos is scientifically accurate and continues to be protective of worker and environmental health".
HBN and other NGOs have previously tried to force asbestos use out of the chlor-alkali industry through action under the revised TSCA. The chemical is among the first ten substances subject to risk evaluation under the new law.
But the EPA recently moved against banning new asbestos products outright. Its proposed significant new use rule (Snur) for asbestos, if adopted, would block industry from initiating new uses without notifying the agency. The EPA could then regulate or deny those requests.
HBN's findings are published in Chlorine and Building Materials: A Global Inventory of Production Technologies, Markets, and Pollution. Phase 1: Africa, The Americas, and Europe. The NGO is planning a second report, which will cover the industry in Asia.