Used primarily in industrial applications as a heat transfer fluid and dielectric fluid in electrical equipment due to its thermal stability and non-flammability. Also found in some older transformer and capacitor systems. Its persistence and toxicity have led to discontinued use, but it can still be encountered as an environmental contaminant in soil, water, and sediments near industrial sites. Historically present in certain pigments and dyes as an unintended byproduct. Monitoring and remediation are important due to bioaccumulation potential in the food chain.