Graphene and its derivatives are heralded as ‘miracle’ materials with manifold applications in different sectors of society from electronics to energy storage to medicine. The increasing exploitation of graphene-based materials (GBMs) necessitates a comprehensive evaluation of the potential impact of these materials on human health and the environment. Here we discuss synthesis and characterization of GBMs as well as human and environmental hazard assessment of GBMs using in vitro and in vivo model systems with the aim to understand the properties that underlie the biological effects of these materials; not all GBMs are alike, and it is essential that we disentangle the structure-activity relationships for this class of materials.

Synthesis of clean double-walled carbon nanotubes by a catalytic chemical vapour deposition (CCVD) method is reported; the catalyst is a Mg_{1 − x}Co_xO solid solution containing additions of Mo oxide; this MgO-based catalyst can be easily removed, leading to gram-scale amounts of clean carbon nanotubes, 77% of which are double-walled carbon nanotubes.

The impact of carbon nanotubes (CNTs) on the aquatic environment was investigated by examining the properties of raw CNTs under several environmental conditions and using developing zebrafish (Danio rerio) embryos. The agglomerate size for single‐walled CNTs (SWCNTs) was significantly larger at pH 11 or greater and was stable at temperatures from 4 to 40°C and salinities from 0 to 30 ppt. Exposure to SWCNTs induced a significant hatching delay in zebrafish embryos between 52 to 72 h postfertilization (hpf) at concentrations of greater than 120 mg/L, but 99% of the exposed embryos hatched by 75 hpf. Double‐walled CNTs also induced a hatching delay at concentrations of greater than 240 mg/L, but carbon black did not affect hatching at the concentrations tested. Molecular and cellular analysis showed that the embryonic development of the exposed embryos up to 96 hpf was not affected at SWCNT concentrations of up to 360 mg/L. Scanning‐electron microscopic inspection showed that the size of the pores on the embryo chorion was nanoscaled and that the size of SWCNT agglomerates was microscaled or larger, indicating that the chorion of zebrafish embryos was an effective protective barrier to SWCNT agglomerates. The hatching delay observed in this study likely was induced by the Co and Ni catalysts used in the production of SWCNTs that remained at trace concentrations after purification. This study suggests that materials associated with raw SWCNTs (perhaps metal contaminants) have the potential to affect aquatic life when released into the aquatic environment.