Controlling techniques and characteristics of organophosphate esters in building environment: A review

Organophosphate esters (OPEs) are widely used as flame retardants, plasticizers, stabilizers, and antifoaming agents in various building materials, such as plastics, foam, coatings, textiles and furniture, and interior decoration materials. In general, most OPEs are combined physically rather than chemically during production. This makes these chemical compounds to be easily released in an indoor environment. Also, previous studies have shown that OPEs were commonly found in an indoor environment at elevated concentrations. Long-term exposure to high concentrations of OPEs in an indoor environment might result in certain health risks. However, there is limited information on the distribution characteristics and risk assessment of OPEs in the building environment. In this study, we discussed the properties, applications, and biological toxicity of common OPEs. In addition, we reviewed the environmental behavior, pollution characteristics, and exposure level of OPEs in the building environment. Building materials and household products are important sources of OPEs in an indoor environment. The levels of OPEs in these productions were significantly associated with the concentration of OPEs in indoor air and dust. In general, indoor air and dust are regarded as the two major sinks of OPEs in the building environment. However, more volatile OPEs, such as TCIPP, TCEP, and TnBP were found predominantly in indoor air, while less volatile OPEs, such as TDCIPP and TPhP were often detected in dust due to their low vapor pressure and high affinity for particles. In general, humans can be exposed to OPEs in a building environment through three main routes of exposure: inhalation, dermal absorption, and ingestion. This study revealed that dust ingestion is the dominant route of human exposure to OPEs, while dermal absorption and inhalation were minor contributors to the total daily exposures. In addition, the relative mass transfer model and release characteristics of OPEs in the building environment were also introduced in this study. Based on the characteristics of OPEs in the building environment, the controlling techniques, which include microporous control technology, barrier control technology, compound purification technology, and an alternative strategy of OPEs, were introduced. However, prospects for future research were considered.