Cytotoxicity of Biochar: A Workplace Safety Concern?

Abstract

Biochar has a number of environmental applications, including soil amendment for agriculture, remediation of contaminated soils and sediments, and climate change mitigation. Dust formed during its production and field application may pose a health risk, but the cytotoxicity of biochar has, to the best of our knowledge, not previously been investigated. Therefore, we measured the concentration-dependent cytotoxicity of biochar on an NIH 3T3 mouse fibroblast cell line. We used a contaminant trap experiment to measure the total and nondesorbable polycyclic aromatic hydrocarbon (PAH) fractions of the biochar. PAH release was found to be negligible because of the biochar’s strong PAH sorption potential. The biochar was nevertheless observed to have a cytotoxic effect on the fibroblast cells; the EC10 values were 49.6 and 18.8 μg/mL after incubation for 24 and 48 h, respectively. This cytotoxic effect is likely to relate to the particulate nature and size distribution of the biochar; the biochar had particles similar in size to atmospheric particulate matter (PM2.5) that bound to the fibroblast cell surface. To minimize the risk of exposure, practitioners should wear respiratory protective equipment during biochar production. During field application, biochar should be applied in slurries and should always be mixed with a soil matrix to avoid secondary dust formation.

Environmental transformation of natural and engineered carbon nanoparticles and implications for the fate of organic contaminants

“…Apart from (bio)chemical transformation, cells can also physically interact with CNPs including soot, [86][87][88] biochar particles, 89 and CNTs. 90,91 In such cases the CNPs are immobilized by aggregation or ingestion, while at the same time inducing negative biological effects on the cells (such as cytotoxicity).…”

Application of biochar-based materials in environmental remediation: from multi-level structures to specific devices

“…The understanding that biochar is a heterogeneous aggregation of particles with different sizes that have gradually replaced the previous recognition (Zhang et al 2019). Beside bulk biochar, small-sized biochar (dissolved and nanometer-scale biochar) has also been found to be an important component of biochar (Kang et al 2015;Lian and Xing 2017;Oleszczuk et al 2016;Saxena et al 2014;Sigmund et al 2017;Spokas et al 2014;Wang et al 2012Wang et al , 2013Yue et al 2019;Zhang et al 2019).…”

Comprehensive review on production and utilization of biochar

“…Therefore, the workplace should be well ventilated. Sigmund et al [165] investigated the cytotoxicity of biochar and reported that cytotoxic effects were likely related to its particulate nature and size distribution. They also suggested that, to minimize the risk of exposure, operators should wear respiratory protective equipment during biochar production and its application in the field.…”