The Stockholm Convention on POPs is a pact between 186 countries to protect human health and the environment from highly hazardous chemical pollutants that persist in the environment and accumulate in living organisms.
The three substances, which are set to be considered by the POPs review committee in October this year, include long-chain perfluorocarboxylic acids (LC-PFCAs), chlorpyrifos and medium-chain chlorinated paraffins (MCCPs) – the latter being led on by the UK.
The consultations, held last year, ask for submissions on the socio-economic impact of restricting MCCPs and LC-PFCAs, as these chemicals are at the risk management stage of the process. They are still at the stage of considering the nature of the risk presented by chlorpyrifos so information on this was requested in the consultations.
Long-chain PFCAs are used for a wide range of products from medical devices to cookware, and form part of the group of per- and polyfluorinated alkyl substances (PFAS) which have been making headlines recently due to concerns over their impact on the environment and human health.
Information in the public domain on the historic and current production of long-chain PFCAs is limited as the focus has shifted to shorter chains, however they have been found to be extremely persistent in the environment.
AGC Chemicals Europe Ltd responded to DEFRA’s consultation that many of the listed uses of LC-PFCAs are applications for producing polytetrafluoroethylene (PTFE) micro-powders rather than specific applications for PFCAs.
AGC also added that their understanding is that LC-PFCAs are effectively encapsulated in PTFE and are therefore unlikely to leach.
They noted that if LC-PFCAs were listed in Annex A of the Stockholm Convention for elimination, an exemption for the transport of PTFE micro-powders, which are used to manufacture of non-stick products, may be needed so that a higher level of unreacted monomer can be allowed prior to the micropowders being further purified.
They also recommended that all PTFE micro-powder applications should be exempted if C9-C21 PFCAs are present as non-intentionally added substances below agreed thresholds.
In terms of the thermal decomposition of fluoropolymers, which was referred to in the risk management evaluation, AGC recommended that a minimum temperature of 800°C is used if incineration is used for disposal, and if it is considered as hazardous waste, then a temperature of 1,100°C is required.
MCCPs are chlorinated paraffins with carbon chain lengths in the range 14 to 17 and consisting of at least 45% chlorine by weight. Concerns have been raised about their impact on human health.
As part of the consultation, the Chartered Institution of Wastes Management (CIWM) reported that MCCPs have been used in a range of products such as flame retardants and plasticisers in plastics, rubbers, inks, paints, adhesives, surface coatings and in leather from shoe manufacture in the UK.
They also reported that they believe MCCPs are still used as secondary plasticisers in some flexible polyvinyl chloride (PVC) applications where flame-retardancy is important. However, they said this is becoming less common.
H&I Chemicals Ltd reported that replacements for MCCPs are “significantly more expensive”, and do not generally offer flame-retardant properties, and said a ban would increase the cost of common products which use them. They described them as being widely used as plasticisers, to make materials flexible.
H&I Chemicals suggested, according to the consultation summary, that: “providing there are adequate controls on the use of MCCPs during production processes, there should be minimal risk of release of MCCPs to the environment”.
Chlorpyrifos is a pesticide that was phased-out as a biocide in Europe from around 2018, however it is still used in other countries, for example as a termite control in buildings. The government launched two consultations on chlorpyrifos, the second focusing on long-range transport effects, but did not publish any responses in its summary.