Triphenyl phospate (TPP or TPHP) is a toxic flame retardant used in polyurethane foam for furniture and children’s products, as a component in the product known as Firemaster 550, and in electronics casings and other plastics. It is also used as a plasticizer and is used in other types of products, including nail polish.
TPP is mixed into rather than chemically bound to the foam and plastic it’s used in and can escape into the indoor and outdoor environment. TPP has been widely detected in household dust, and kids in particular are known to ingest house dust because of their tendency to put toys and their hands into their mouths. Research has also shown greater exposure after use of nail polish.
TPP has been detected in breast milk and its metabolites have been found in urine, with a U.S. study finding higher exposure among toddlers than their mothers.
TPP has been linked to a number of toxic effects:
- Obesity: Laboratory animals exposed to Firemaster 550 had excessive weight gain, and cell-based studies implicate TPP specifically in stimulating development of fat cells and impeding bone formation.
- Hormone disruption: Human and laboratory evidence suggest TPP can disrupt hormonal systems, with cell-based and animal studies finding effects on sex hormone levels. In men, greater exposure to TPP has been associated with altered levels of hormones and lower sperm concentrations.
- Thyroid: Laboratory and cell-based studies have found TPP affects thyroid hormone synthesis, which can have impacts on development.
- Aquatic toxicity: EPA has ranked TPP as having very high acute and chronic aquatic toxicity based on toxicity to fish.
The Washington State Legislature passed a law in 2016 directing state agencies to assess the compound for possible restrictions.
Manufacturers should choose safer materials and chemicals, including materials that do not require chemical flame retardants to meet flammability standards.
You can reduce your exposure to TPP and other flame retardants used in polyurethane foam by making sure furniture you purchase is labeled as free of flame retardants. Make sure any children’s products you or your childcare provider use are not labeled as meeting the California TB 117 flammability standard.