The European Chemicals Agency (ECHA) has recently proposed the addition of O,O,O-triphenyl phosphorothioate (TPPT), identified by EC Number 209-909-9 and CAS Number 597-82-0, to its list of substances of very high concern (SVHC) under Article 57 of the REACH regulation. This proposal, submitted by the Netherlands, stems from TPPT's classification as persistent, bioaccumulative, and toxic (PBT).
What is O,O,O-Triphenyl Phosphorothioate?
TPPT is an organophosphorus compound commonly used as a flame retardant, plasticizer, and lubricant additive. It is primarily employed in industrial applications, including in the manufacturing of plastics, coatings, and rubbers, due to its ability to enhance material properties such as flexibility, durability, and resistance to fire.
Environmental and Health Risks of TPPT
While TPPT is valued for its industrial applications, it poses significant environmental and health risks, leading to its proposed classification as a substance of very high concern.
- Persistence in the Environment: TPPT is highly persistent in various environmental compartments, particularly in water and soil. According to the Annex XV report, TPPT has an extremely long degradation half-life, especially in aquatic environments. Tests indicate that TPPT remains stable with no significant degradation over extended periods, posing a long-term environmental threat due to its inability to break down easily.
- Bioaccumulation in Living Organisms: TPPT's chemical properties make it highly lipophilic, meaning it tends to accumulate in the fatty tissues of living organisms. Studies have shown that TPPT can bioaccumulate in aquatic organisms, such as fish, with a bioconcentration factor (BCF) exceeding 2000. This level of bioaccumulation is concerning because it implies that TPPT could build up in the food chain, potentially affecting predators, including humans, who consume contaminated fish.
- Toxicity to Aquatic Life: TPPT has been found to be toxic to aquatic organisms, particularly fish. It affects the early life stages of fish, with studies on rainbow trout indicating a No Observed Effect Concentration (NOEC) for larval survival that is significantly below safety thresholds. This toxicity poses a risk to aquatic ecosystems, as it can lead to reduced fish populations and disrupt aquatic food webs.
- Potential Human Health Risks: Although the primary focus of the current assessment is on environmental impacts, there are potential indirect human health risks. Due to its persistence and ability to bioaccumulate, TPPT could potentially enter the human body through the consumption of contaminated water or food, particularly fish. The long-term health effects of low-level exposure to TPPT are not fully understood, but its classification as toxic raises concerns about possible impacts on human health.
Current Uses of TPPT and Industry Implications
TPPT is widely used in various industrial processes. Some of the primary uses include:
- Plastic Manufacturing: TPPT is used as a plasticizer in the production of flexible PVC and other plastics, providing improved flexibility and durability.
- Coatings and Adhesives: It serves as an additive to improve the fire resistance and performance of coatings, adhesives, and sealants.
- Lubricant Additives: TPPT is used in lubricants to enhance their properties, such as reducing wear and improving thermal stability.
Given its wide range of applications, the proposal to classify TPPT as an SVHC could have significant implications for industries that rely on this chemical. Companies using TPPT in their products would need to assess the potential risks and consider alternatives. Additionally, if TPPT is added to the SVHC list, manufacturers and importers would be required to provide more detailed information about its use and safe handling, and they may need to seek authorisation for continued use in the European Union.
Public Consultation and Next Steps
The inclusion of TPPT on the SVHC list is currently open for public consultation. Stakeholders, including industry representatives, environmental organisations, and the public, are invited to submit their comments by 14 October 2024.
