Assessment of Potential Human Health Consequences Associated with Processing and Handling of Switchgrass Biomass for Bio-Based Products

In an expanding, regenerative bio-based economy, the role of cheap, low impact lignocellulosic switchgrass (Panicum virgatum L.) biomass is that of a steady energy source, as we make the transition from fossil fuels to wind and solar power. However epidemiological studies have linked worker exposure to high concentrations of bioaerosols when handling and processing biomass in a biofuel plant. The primary aim of this study was to quantify personal and environmental exposure of workers to dust, endotoxins and bioaerosol present during handling and processing of switchgrass biomass, and to describe airborne fungal and bacterial communities associated with their daily activity. For the purpose of this study, a total of 111 airborne dust samples were collected using a stationary 37-mm open face cassette across the processing facility. Similarly, 27 stationary respirable and 15 personal exposure dust samples were also collected using an aluminum cyclone. Collected samples were quantified for dust concentration using gravimetric analysis. Captured endotoxins were analyzed using Limulus amebocyte lysate, while total bioaerosols were enumerated using a modified CAMENA method, and airborne microbial communities were identified using sequencing a portion of the bacterial 16S rRNA gene and fungal ITS region. The environmental exposure levels to fungi (median = 118 x 104 cfu/m3), bacteria (median = 29 x 106 cfu/m3), endotoxin (median = 2.6 x 104 EU/m3) and, organic dust (median = 8 mg/m3) were in general high across the processing facility in comparison to occupational exposure limit (OEL) recommended to the industry by the Dutch health council.