Human Indoor Exposure to Airborne Halogenated Flame Retardants: Influence of Airborne Particle Size

Abstract

Inhalation of halogenated flame-retardants (HFRs) released from consumer products is an important route of exposure. However, not all airborne HFRs are respirable, and thus interact with vascular membranes within the gas exchange (alveolar) region of the lung. HFRs associated with large (>4 µm), inhalable airborne particulates are trapped on the mucosal lining of the respiratory tract and then are expelled or swallowed. The latter may contribute to internal exposure via desorption from particles in the digestive tract. Exposures may also be underestimated if personal activities that re-suspend particles into the breathing zone are not taken into account. Here, samples were collected using personal air samplers, clipped to the participants’ shirt collars (n = 18). We observed that the larger, inhalable air particulates carried the bulk (>92%) of HFRs. HFRs detected included those removed from commerce (i.e., polybrominated diphenyl ethers (Penta-BDEs: BDE-47, -85, -100, -99, and -153)), their replacements; e.g., 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB or EH-TBB); bis(2-ethylhexyl) 3,4,5,6-tetrabromophthalate (TBPH or BEH-TEBP) and long-produced chlorinated organophosphate-FRs (ClOPFRs): tris(2-chloroethyl)phosphate (TCEP), tris(1-chloro-2-propyl)phosphate (TCPP or TCIPP), and tris(1,3-dichloro-2-propyl)phosphate (TDCPP or TDCIPP). Our findings suggest estimates relying on a single exposure route, i.e., alveolar gas exchange, may not accurately estimate HFR internal dosage, as they ignore contributions from larger inhalable particulates that enter the digestive tract. Consideration of the fate and bioavailability of these larger particulates resulted in higher dosage estimates for HFRs with log Koa < 12 (i.e., Penta-BDEs and ClOPFRs) and lower estimates for those with log Koa > 12 (i.e., TBB and TBPH) compared to the alveolar route exposure alone. Of those HFRs examined, the most significant effect was the lower estimate by 41% for TBPH. The bulk of TBPH uptake from inhaled particles was estimated to be through the digestive tract, with lower bioavailability. We compared inhalation exposure estimates to chronic oral reference doses (RfDs) established by several regulatory agencies. The U.S. Environmental Protection Agency (EPA) RfD levels for several HFRs are considered outdated; however, BDE-99 levels exceeded those suggested by the Dutch National Institute for Public Health and the Environment (RIVM) by up to 26 times. These findings indicate that contributions and bioavailability of respirable and inhalable airborne particulates should both be considered in future risk assessments.

Human Exposure to Legacy and Emerging Halogenated Flame Retardants via Inhalation and Dust Ingestion in a Norwegian Cohort

“…In a recent study on occupational and residential FR exposure of gymnastic coaches and gymnasts, air and dust samples were collected from gyms and homes ( n = 4) in Seattle, WA, where EH-TBB (from <0.1 to 55 ng/m 3 ) and BEH-TEBP (from <0.1 to 19 ng/m 3 ) were found to be the major FRs detected in the home respirable air samples (particles of <4 μm), contributing 60% to the total mean of the respirable air FR content . Total air contributions of the PentaBDE replacements (EH-TBB + BEH-TEBP) were found to be approximately 2–6 times higher than the sum of the PentaBDEs in several different indoor environments . The finding of relatively low levels of PBDEs in air samples compared to those from older studies in Norway, Denmark, and Germany (Table S11, Supporting Information), together with the detection of high concentrations of EH-TBB in air (and BEH-TEBP in dust) in the present study, could also reflect the replacement of the banned PentaBDE formulation with technical FR mixtures, such as Firemaster 550, Firemaster BZ-54, and DP-45 (manufactured by Chemtura), which contain EH-TBB and BEH-TEBP as the two main brominated components. ,, The median concentration of DBE-DBCH in this study was lower than that reported in Norwegian households and classrooms (78 and 47 pg/m 3 , respectively), U.K. homes and offices (110 and 290 pg/m 3 , respectively), and Swedish indoor environments (55 pg/m 3 ) .…”

Advances in Flame Retardant Poly(Lactic Acid)

“…The halogenated FR leach to the environment throughout the life cycle of treated objects as dust in indoor exposure, mechanical recycling of plastics and metals as well as incineration and open burning of household wastes, such as electronic parts, paints, solvents, and textiles [15,16]. While most halogenated flame retardants are classified as toxic, they also act as potent precursors for the formation of polybrominated dibenzo- p -dioxins, dibenzofurans and other radical chemicals species that are dangerous to flora and fauna [12,16,17]. They are particularly associated with such deformities such as endocrine and thyroid disruption, immune toxicity, reproductive defects, cancer, neonatal and fetal deformities, child development and neurologic functions [12,14,18,19,20].…”

Bioaccumulation and effects of dietary exposure to the alternative flame retardant, bis(2‐ethylhexyl) tetrabromophthalate (TBPH), in the Atlantic killifish, Fundulus heteroclitus

“…It has been suggested that TBPH may act as a metabolic disrupting agent or an environmental obesogen (i.e., stimulating adipogenesis; as reviewed in Capitao et al 2017). For example, both Firemaster 550 and TBPH alone induced lipid accumulation in a dose-dependent manner in mammalian cultured cells (Tung Guardia et al . et al 2017.…”