La Guardia Mark J, Schreder Erika D, Uding Nancy, Hale Robert C
College of William & Mary, Virginia Institute of Marine Science, P.O. Box 1346, Gloucester Point, VA 23062, USA.
Toxic-Free Future, 4649 Sunnyside Ave N, Suite 540, Seattle, WA 98103, USA.
Int J Environ Res Public Health. 2017 May 9;14(5):507. doi: 10.3390/ijerph14050507.
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 < 12 (i.e., Penta-BDEs and ClOPFRs) and lower estimates for those with log > 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 (RDs) established by several regulatory agencies. The U.S. Environmental Protection Agency (EPA) RD 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.
吸入消费品释放的卤代阻燃剂（HFRs）是重要的暴露途径。然而，并非所有空气中的HFRs都可吸入，因此它们会与肺气体交换（肺泡）区域内的血管膜相互作用。与大颗粒（>4 µm）、可吸入空气颗粒物相关的HFRs会被困在呼吸道的粘膜衬里上，然后被排出或吞咽。后者可能通过从消化道颗粒上解吸而导致体内暴露。如果不考虑将颗粒重新悬浮到呼吸区域的个人活动，暴露量可能也会被低估。在这里，使用夹在参与者衬衫领口的个人空气采样器收集样本（n = 18）。我们观察到，较大的、可吸入空气颗粒物携带了大部分（>92%）的HFRs。检测到的HFRs包括已退出市场的物质（即多溴二苯醚（五溴二苯醚：BDE-47、-85、-100、-99和-153））及其替代品；例如，2-乙基己基2,3,4,5-四溴苯甲酸酯（TBB或EH-TBB）；双（2-乙基己基）3,4,5,6-四溴邻苯二甲酸酯（TBPH或BEH-TEBP）以及长期生产的氯化有机磷酸酯阻燃剂（ClOPFRs）：磷酸三（2-氯乙基）酯（TCEP）、磷酸三（1-氯-2-丙基）酯（TCPP或TCIPP）和磷酸三（1,3-二氯-2-丙基）酯（TDCPP或TDCIPP）。我们的研究结果表明，仅依靠单一暴露途径（即肺泡气体交换）的估计可能无法准确估计HFR的体内剂量，因为它们忽略了进入消化道的较大可吸入颗粒物的贡献。考虑这些较大颗粒物的归宿和生物利用度后，与仅通过肺泡途径暴露相比，对于log < 12的HFRs（即五溴二苯醚和ClOPFRs），剂量估计值更高，而对于log > 12的HFRs（即TBB和TBPH），剂量估计值更低。在所检测的这些HFRs中，最显著的影响是TBPH的估计值低了41%。估计从吸入颗粒中摄取的大部分TBPH是通过消化道，生物利用度较低。我们将吸入暴露估计值与几个监管机构确定的慢性口服参考剂量（RDs）进行了比较。美国环境保护局（EPA）对几种HFRs的RD水平被认为过时；然而，BDE-99的水平比荷兰国家公共卫生与环境研究所（RIVM）建议的水平高出多达26倍。这些研究结果表明，在未来的风险评估中应同时考虑可吸入和可呼吸空气颗粒物的贡献及生物利用度。
