Watson-Wright Christa, Singh Dilpreet, Demokritou Philip
Center for Nanotechnology and Nanotoxicology, Department of Environmental Health, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA.
NanoImpact. 2017 Jan;5:29-40. doi: 10.1016/j.impact.2016.12.003. Epub 2016 Dec 29.
Nano-enabled thermoplastics are part of the growing market of nano-enabled products (NEPs) that have vast utility in several industries and consumer goods. The use and disposal of NEPs at their end of life has raised concerns about the potential release of constituent engineered nanomaterials (ENMs) during thermal decomposition and their impact on environmental health and safety. To investigate this issue, industrially relevant nano-enabled thermoplastics including polyurethane, polycarbonate, and polypropylene containing carbon nanotubes (0.1 and 3% w/v, respectively), polyethylene containing nanoscale iron oxide (5% w/v), and ethylene vinyl acetate containing nanoscale titania (2 and 5% w/v) along with their pure thermoplastic matrices were thermally decomposed using the recently developed lab based Integrated Exposure Generation System (INEXS). The life cycle released particulate matter (called LCPM) was monitored using real time instrumentation, size fractionated, sampled, extracted and prepared for toxicological analysis using primary small airway epithelial cells to assess potential toxicological effects. Various cellular assays were used to assess reactive oxygen species and total glutathione as measurements of oxidative stress along with mitochondrial function, cellular viability, and DNA damage. By comparing toxicological profiles of LCPM released from polymer only (control) with nano-enabled LCPM, potential nanofiller effects due to the use of ENMs were determined. We observed associations between NEP properties such as the percent nanofiller loading, host matrix, and nanofiller chemical composition and the physico-chemical properties of released LCPM, which were linked to biological outcomes. More specifically, an increase in percent nanofiller loading promoted a toxicological response independent of increasing LCPM dose. Importantly, differences in host matrix and nanofiller composition were shown to enhance biological activity and toxicity of LCPM. This work highlights the importance of assessing the toxicological properties of LCPM and raises environmental health and safety concerns of nano-enabled products at their end of life during thermal decomposition/incineration.
纳米增强热塑性塑料是纳米增强产品(NEPs)不断增长的市场的一部分,这些产品在多个行业和消费品中具有广泛用途。NEPs在其使用寿命结束时的使用和处置引发了人们对热分解过程中成分工程纳米材料(ENMs)潜在释放及其对环境健康和安全影响的担忧。为了研究这个问题,使用最近开发的基于实验室的综合暴露生成系统(INEXS)对工业相关的纳米增强热塑性塑料进行热分解,这些材料包括分别含有碳纳米管(0.1%和3% w/v)的聚氨酯、聚碳酸酯和聚丙烯、含有纳米级氧化铁(5% w/v)的聚乙烯以及含有纳米级二氧化钛(2%和5% w/v)的乙烯醋酸乙烯酯,以及它们的纯热塑性基体。使用实时仪器监测生命周期释放的颗粒物(称为LCPM),进行尺寸分级、采样、提取,并使用原代小气道上皮细胞进行毒理学分析准备,以评估潜在的毒理学效应。使用各种细胞测定法评估活性氧和总谷胱甘肽,作为氧化应激的测量指标,同时评估线粒体功能、细胞活力和DNA损伤。通过比较仅聚合物(对照)释放的LCPM与纳米增强LCPM的毒理学特征,确定了由于使用ENMs而产生的潜在纳米填料效应。我们观察到NEP特性(如纳米填料负载百分比、主体基体和纳米填料化学成分)与释放的LCPM的物理化学性质之间的关联,这些性质与生物学结果相关。更具体地说,纳米填料负载百分比的增加促进了与LCPM剂量增加无关的毒理学反应。重要的是,主体基体和纳米填料组成的差异显示出增强了LCPM的生物活性和毒性。这项工作强调了评估LCPM毒理学特性的重要性,并提出了纳米增强产品在热分解/焚烧生命周期结束时对环境健康和安全的担忧。