28-Day inhalation toxicity of graphene nanoplatelets in Sprague-Dawley rats
Creators: name: Kim, Jin Kwon
name: Shin, Jae Hoon
name: Lee, Jong Seong
name: Hwang, Joo Hwan
name: Lee, Ji Hyun
name: Baek, Jin Ee
name: Kim, Tae Gyu
name: Kim, Boo Wook
name: Kim, Jin Sik
name: Lee, Gun Ho
name: Kangho Ahn
name: Han, Sung Gu
name: Bello, Dhimiter
name: Yu, Il Je
Publisher: name: Taylor & Francis
Year: 2016
Subjects: subject: Biochemistry
subject: Medicine
subject: Cell Biology
subject: Molecular Biology
subject: Pharmacology
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: FOS: Chemical sciences
subject: Immunology
subject: FOS: Clinical medicine
subject: FOS: Clinical medicine
subject: 69999 Biological Sciences not elsewhere classified
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: 60506 Virology

description: Graphene, a two-dimensional engineered nanomaterial, is now being used in many applications, such as electronics, biological engineering, filtration, lightweight and strong nanocomposite materials, and energy storage. However, there is a lack of information on the potential health effects of graphene in humans based on inhalation, the primary engineered nanomaterial exposure pathway in workplaces. Thus, an inhalation toxicology study of graphene was conducted using a nose-only inhalation system for 28 days (6 h/day and 5 days/week) with male Sprague-Dawley rats that were then allowed to recover for 1-, 28-, and 90-day post-exposure period. Animals were separated into 4 groups (control, low, moderate, and high) with 15 male rats (5 rats per time point) in each group. The measured mass concentrations for the low, moderate, and high exposure groups were 0.12, 0.47, and 1.88 mg/m<sup>3</sup>, respectively, very close to target concentrations of 0.125, 0.5, and 2 mg/m<sup>3</sup>. Airborne graphene exposure was monitored using several real-time instrumentation over 10 nm to 20 μm for size distribution and number concentration. The total and respirable elemental carbon concentrations were also measured using filter sampling. Graphene in the air and biological media was traced using transmission electron microscopy. In addition to mortality and clinical observations, the body weights and food consumption were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for blood biochemical tests, and the organ weights were measured. No dose-dependent effects were recorded for the body weights, organ weights, bronchoalveolar lavage fluid inflammatory markers, and blood biochemical parameters at 1-day post-exposure and 28-day post-exposure. The inhaled graphenes were mostly ingested by macrophages. No distinct lung pathology was observed at the 1-, 28- and 90-day post-exposure. The inhaled graphene was translocated to lung lymph nodes. The results of this 28-day graphene inhalation study suggest low toxicity and a NOAEL of no less than 1.88 mg/m<sup>3</sup>.