Occurrence of and human exposure to TBBPA and its derivatives in indoor dust in China

Indoor dust is one of the potential sources of human exposure to pollutants. As a class of brominated flame retardants, tetrabromobisphenol A (TBBPA), tetrabromobisphenol S (TBBPS) and tetrachlorobisphenol A (TCBPA) are widely used in consumer products. TBBPA is the most widely used brominated flame retardant, and has been detected in various environment matrices and human samples. Toxicological and epidemiological studies have shown that TBBPA, TBBPS and TCBPA are associated with potential endocrine disrupting effects, which can cause adverse effects on humans and animals. Although many studies have reported the occurrence of TBBPA in indoor dust, the nationwide survey on the levels and distribution profile of TBBPA, TBBPS and TCBPA in indoor dust in China is still limited. In addition, studies mostly focused on TBBPA in recent years, little was known about the occurrence of TBBPS and TCBPA in the indoor environment. Therefore, comprehensive investigation of TBBPAs in indoor dust is required. In this study, 94 indoor dust samples collected from 23 provinces and 2 municipalities in China, were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for TBBPA, TBBPS and TCBPA. TBBPA was the predominant among the three analogues (contribution to the total concentrations: >= 88.3%), with a concentration range of not detected (nd)similar to 1840 ng/g (mean: 43.3 ng/g). The highest total concentration of TBBPAs (Sigma 3TBBPAs; sum of TBBPA, TBBPS and TCBPA) was found in dusts from Eastern China, ranging from 6.84 to 1850 (mean: 178 ng/g). Based on the concentrations measured, human daily intakes of TBBPA, TBBPS and TCBPA through ingestion, dermal contact and inhalation of dust were estimated. Ingestion was the major pathway of human exposure to TBBPAs from dust. The estimated daily intake of Sigma 3TBBPAs through dust ingestion was 3300 pg (kg bw)(-1) d(-1) for children, which was 7-8 times higher than that for adults (422 pg (kg bw)(-1) d(-1)). Children are at a higher risk of being exposed to TBBPAs than adults, which may be due to children have more behaviors of hand-mouth contact and lower body weight. The ecological risk of TBBPA, TBBPS and TCBPA in indoor dust was also estimated. The result showed that the I value of TBBPA in indoor dust calculated from Eastern China was more than 1, which implies that the existence of TBBPA may cause adverse effect in Eastern China. In summary, concentrations and distribution profiles of TBBPA, TBBPS and TCBPA in indoor dust in China were investigated. Human daily intakes of these chemicals and corresponding ecological risks were estimated. The study findings will provide better understanding of the pollution status of TBBPA and its derivatives in the indoor microenvironment in China and a scientific basis for regulation of such chemicals in consumer products.