UN experts recommend eliminating the toxic chemical methoxychlor and take steps towards eliminating plastic additive UV-328 and flame retardant Dechlorane Plus

Geneva, Switzerland: 28 January 2022

At a time when pollution is described by the United Nations as one of the three existential planetary threats currently facing society, along with climate change and loss of biodiversity, more than 250 scientific experts came together in Geneva and online this week, to review scientific data and make recommendations concerning the possible elimination of a number of toxic chemicals known as Persistent Organic Pollutants, or POPs.

The 17th meeting of the POPs Review Committee, held from 24 to 28 January 2022, recommended listing methoxychlor, a pesticide, in Annex A to the Stockholm Convention, without exemptions. Methoxychlor now goes forward to a future meeting of the Conference of the Parties (COP) to the Stockholm Convention in 2023, where a decision to list would be expected to lead to global action towards its elimination or reduction from production and use, as well as the destruction of existing stocks and management of POPs wastes.

Methoxychlor has been used as a replacement for DDT against a wide range of pests including biting flies, houseflies, mosquito larvae, cockroaches and chiggers on field crops, fruit, vegetables, ornamentals as well as on livestock and pets. It is known to be very highly toxic to invertebrates and fish, including through its endocrine-disrupting effects, and has been detected in the environment and biota in the Arctic and in Antarctica, far from its production and use. Methoxychlor has also been detected in human serum, adipose tissues, umbilical cord blood and human breast milk.

The Committee also considered UV-328, a chemical typically found in certain types of plastics, and adopted its risk profile, moving it towards a possible recommendation to the Conference of the Parties for elimination. It noted that UV-328 is likely, as a result of its long-range environmental transport, to lead to significant adverse human health and/or environmental effects, such that global action is warranted. A risk management evaluation will now be prepared, to be discussed at the next POPRC meeting, later this year, when a recommendation for elimination might be made, for consideration at a future Stockholm Convention COP.

The Committee also reached consensus on Dechlorane Plus, a flame retardant that has been in use since the 1960s, adopting the risk profile and moving it towards eventual possible elimination. This chemical is associated with harmful impacts such as oxidative damage, neurodevelopmental toxicity and endocrine disruption. Oxidative stress has been observed in marine macroalgae, fish, marine bivalves, earthworms, birds, and mice. In humans, exposure takes place by consumption of food and drinking water, inhalation of indoor and ambient air, as well as respiratory and oral uptake of dust. It has been detected in human blood and breast milk in many regions of the world, and the human foetus may be exposed via the umbilical cord blood, and breast milk may be an important source of exposure for infants.

Rolph Payet, Executive Secretary of the Stockholm Convention, said that “The recommendation by POPRC to eliminate methoxychlor, a pesticide with long-term ecological and health effects, can contribute to a cleaner, healthier environment and is an important step towards the sound management of chemicals and waste worldwide. Moving other candidate POPs forward to the next stage of review, including the plastic additive UV-328 and flame retardant Dechlorane Plus, also represents vital progress. It  shows that – together- the Basel, Rotterdam and Stockholm Conventions provide the global legal and scientific framework, as well as platform of opportunity, for countries to continue to critically address the global pollution crisis, including from plastic waste.”

Three new proposals for listing additional substances for elimination or restriction were also reviewed for the first time by the Committee, which agreed that long-chain perfluorocarboxylic acids, their salts and related compounds, chlorinated paraffins with carbon chain lengths C14-17 and chlorination levels at or exceeding 45 per cent chlorine by weight and chlorpyrifos all met the screening criteria specified in Annex D to the Convention, moving consideration of these chemical groups to the next review stage by the Committee later this year.

More information on all the chemicals under review is available online:


At a previous meeting, POPRC recommended perfluorohexane sulfonic acid (PFHxS), its salts, and PFHxS-related compounds be listed in Annex A to the Convention without specific exemptions, which will be considered at the face-to-face segment of the tenth meeting of the Conference of Parties to the Stockholm Convention (COP) to be held in June 2022. PFHxS, its salts, and PFHxS-related compounds are a group of industrial chemicals used widely in a number of consumer goods as a surfactant and sealant including in carpets, leather, clothing, textiles, fire-fighting foams, papermaking, printing inks and non-stick cookware. PFHxS, its salts, and PFHxS-related compounds are known to be harmful to human health including the nervous system, brain development, endocrine system and thyroid hormone.

To date, 30 POPs, which covers hundreds of related chemicals, are listed in the Annexes A, B and C to the legally-binding Stockholm Convention. The Convention, which entered into force in 2004 has 185 Parties, and benefits from almost universal coverage across the globe.

Dechlorane Plus is used worldwide as an additive flame retardant in electrical wire and cable coatings, plastic roofing materials, connectors in TV and computer monitors and as non-plasticizing flame retardants in polymeric systems such as nylon and polypropylene plastic. Widely detected in remote areas such as the Arctic and Antarctica, the toxic effects include endocrine disruption, oxidative stress and oxidative damages, and neurotoxicity, and is reported to cross the blood-brain barrier and to be maternally transferred to offspring in several species, including humans. The highest DP levels have been observed in occupationally exposed workers and residents living near production facilities and e-waste recycling sites in Asia.

PFHxS, its salts and related compounds, have unique properties with a high resistance to friction, heat, chemical agents, low surface energy and are used as a water, grease, oil and soil repellent. It is widely utilized in a variety of consumer goods such as carpets, leather, apparel, textiles, firefighting foam, papermaking, printing inks, sealants, and non-stick cookware. PFHxS concentrations are found in biota and humans alike and its elimination takes approximately 8 years. Effects of PFHxS in humans are found to influence the nervous system, brain development, endocrine system and thyroid hormone. For more on PFHxS see:  https://chm.pops.int/Convention/POPsReviewCommittee/Chemicals/tabid/243/Default.aspx

UV-328 is a ubiquitous high-volume additive typically used as an ultra-violet (UV) stabiliser in plastic products such as some personal care products, rubber and coatings. UV-328 is found in the environment and biota, including in remote areas such as the Arctic and the Pacific Ocean, far from its production and use. UV-328 has been found to be transported with, and may subsequently be released from plastic debris, which is taken up for example by seabirds with subsequent accumulation in their tissue, and microplastics. In humans, UV-328 has been detected in breast milk.  It is the first non-halogenated chemical considered by POPRC. Given UV-328’s proliferation in plastic products, its eventual, possible listing would strengthen the Stockholm Convention’s role as a key, additional instrument for governments across the globe to tackle the growing plastic waste crisis.

POPs and the Stockholm Convention

Exposure to Persistent Organic Pollutants (POPs) can lead to serious adverse health effects including certain cancers, birth defects, dysfunctional immune and reproductive systems, greater susceptibility to disease and damage to the central and peripheral nervous systems. Given that these chemicals can be transported over long distances, no one government acting alone can protect its citizens or its environment from POPs. The Stockholm Convention on Persistent Organic Pollutants, adopted in 2001 and entered into force in 2004, is a global treaty requiring its Parties to take measures to eliminate or reduce the release of POPs into the environment, to protect human health and the environment from chemicals that remain intact for long periods, become widely distributed geographically, accumulate in the fatty tissue of humans and wildlife, and have harmful impacts on human health or on the environment.

For more information on the Stockholm Convention, POPs, and POPRC: www.chm.pops.int

For more info:

Technical contact: Kei Ohno Woodall, BRS Secretariat; email: kei.ohno@un.org tel: +41 79 233 3218

Press contact: Charlie Avis, BRS Secretariat email: Charles.avis@un.org tel: +41-79-7304495