Skip to main content

Nanomaterials Ecological Risk Assessment: A study of the long-term effects and risks of nanoscale Iron Oxide used in plastic composites in the aquatic environment

Periodic Reporting for period 1 - NanoERA (Nanomaterials Ecological Risk Assessment: A study of the long-term effects and risks of nanoscale Iron Oxide used in plastic composites in the aquatic environment)

Reporting period: 2015-07-03 to 2017-07-02

Nanoscale copper phthalocyanine (n-CuPc) has been utilized to enhance or modify the properties of many materials and products, including printing inks, coatings for automobile production, plastics and textiles. n-CuPc can improve the mechanical properties and add new features to the products, such as improved transparency, lightfastness (stability under irradiation), heat stability, chemical and bleed resistance, improved processing capabilities and durability. It is estimated that Europe consumed 21 thousand metric tons of CuPc pigments (dry weight basis, both as nano-forms (n-CuPc) and as non-nano-forms) in 2010, of which 25-30% were used in paints and coatings, a significant part in nanoform. The automobile industry is the largest market for organic pigments due to the increasing customer preferences for enhanced colors.
The use of n-CuPc can potentially lead to the release of n-CuPc which may pose environmental and occupational risks, especially to automechanics performing car maintenance and repairs. Even though the automobile industry has risk management measures in place (local exhaust of sanding equipment, face masks) to reduce occupational exposure, the knowledge on fate and hazard of sanding fragments is required for efficient risk management. Furthermore, very little is known about the exposure and hazard of released n-CuPc from automobile coatings in environmental and occupational settings.
The objective of NanoERA project is to address both the release of n-CuPc-containing fragments from commercial coatings in realistic occupational situations and the hazard of the released fragments to human health so as to provide information to the automobile industry regarding the potential risk to the workers employed in this sector.
Three specific studies were performed from the beginning of the project to the end. Firstly, we developed methodology and measured the release of n-CuPc-containing fragments from automobile coatings from sanding, which is representative of repair processes. Secondly, we investigated how the physicochemical properties of released fragments from automobile coating containing n-CuPc changed in biological (cell culture) media. Thirdly, we identified the hazard of the released n-CuPc based on the use of an in vitro macrophage model (J774 A1).
The results showed similar distribution of size and quantity of fragments released from nano-enabled coatings and those released from control samples. The fragments showed higher agglomeration in Rosewell Park Memorial Institute (RPMI) than pristine n-CuPc. The toxicity of the fragment released from the coating and reference materials was similar and below the toxicity of pristine n-CuPc.
The main results demonstrated that when the n-CuPc was embedded in a polymer its toxicity was suppressed. The lack of difference in toxicity between fragments from nano-enabled and reference coatings can be explained by the fact that the coating matrix dominated the toxicity of released fragments, preventing the toxicity of the embedded n-CuPc. One hypothesis to explain the relatively low toxicity of the n-CuPc embedded in paint could be that the bioavailability of n-CuPc is reduced by matrix. This results in effective size of fragments in micrometre agglomerates which may contribute to the lower uptake of fragments, resulting in a lower dose in the cells and therefore a low toxicity of fragments to J774 cells.
This is the first report concerning the cytotoxicity of released n-CuPc from automobile coatings to macrophages. We are first to study the cross-linked, isocyanate-hardened matrix that is typical for coatings and is quite different chemistry than the soft polymer binders used in paints, epoxy or thermoplastics. We are the first to study copper-containing nanomaterial fillers, which a priori could result in quite different response than carbon nanotube (CNT) fillers or TiO2 fillers in the (few) previous studies of fragment toxicity. Further, we combined assessment of both the release of nanoparticles in realistic conditions and the evaluation of hazard of the released fragments, specifically by using a macrophage model. In a preliminary risk screening, we evaluated the human risk to workers through the whole life cycle of the product. The study is thus very important to the automobile industry since it assesses the potential risk to the workers employed in this sector.
Pigments and their application in automobile coatings