Center for Nanotechnology and Nanotoxicology, T. H. Chan School of Public Health, Harvard University , 665 Huntington Avenue, Boston, Massachusetts 02115, United States.
Department of Civil and Environmental Engineering, University of Rhode Island , 1 Lippitt Road, Kingston, Rhode Island 02881, United States.
Environ Sci Technol. 2017 May 2;51(9):5222-5232. doi: 10.1021/acs.est.6b06448. Epub 2017 Apr 20.
Nano-enabled products are ultimately destined to reach end-of-life with an important fraction undergoing thermal degradation through waste incineration or accidental fires. Although previous studies have investigated the physicochemical properties of released lifecycle particulate matter (called LCPM) from thermal decomposition of nano-enabled thermoplastics, critical questions about the effect of nanofiller on the chemical composition of LCPM still persist. Here, we investigate the potential nanofiller effects on the profiles of 16 Environmental Protection Agency (EPA)-priority polycyclic aromatic hydrocarbons (PAHs) adsorbed on LCPM from thermal decomposition of nano-enabled thermoplastics. We found that nanofiller presence in thermoplastics significantly enhances not only the total PAH concentration in LCPM but most importantly also the high molecular weight (HMW, 4-6 ring) PAHs that are considerably more toxic than the low molecular weight (LMW, 2-3 ring) PAHs. This nano-specific effect was also confirmed during in vitro cellular toxicological evaluation of LCPM for the case of polyurethane thermoplastic enabled with carbon nanotubes (PU-CNT). LCPM from PU-CNT shows significantly higher cytotoxicity compared to PU which could be attributed to its higher HMW PAH concentration. These findings are crucial and make the case that nanofiller presence in thermoplastics can significantly affect the physicochemical and toxicological properties of LCPM released during thermal decomposition.
纳米增强产品最终会达到使用寿命终点，其中很大一部分会通过废物焚烧或意外火灾进行热降解。尽管先前的研究已经调查了纳米增强热塑性塑料热分解释放的生命周期颗粒物质（称为 LCPM）的物理化学性质，但关于纳米填料对 LCPM 化学成分影响的关键问题仍然存在。在这里，我们研究了纳米填料对从纳米增强热塑性塑料热分解中吸附在 LCPM 上的 16 种美国环保署（EPA）优先多环芳烃（PAHs）的浓度分布的潜在影响。我们发现，纳米填料在热塑性塑料中的存在不仅显著增加了 LCPM 中总 PAH 浓度，而且更重要的是增加了高分子量（HMW，4-6 环）PAHs 的浓度，这些 PAHs 的毒性比低分子量（LMW，2-3 环）PAHs 高得多。在体外细胞毒理学评价中，对于用碳纳米管增强的聚氨酯热塑性塑料（PU-CNT）的情况，也证实了这种纳米特定的效应。与 PU 相比，来自 PU-CNT 的 LCPM 表现出显著更高的细胞毒性，这可能归因于其更高的 HMW PAH 浓度。这些发现至关重要，表明纳米填料在热塑性塑料中的存在会显著影响热分解过程中释放的 LCPM 的物理化学和毒理学性质。
