New investigations into the genotoxicity of cobalt compounds and their impact on overall assessment of genotoxic risk

Abstract

The genotoxicity of cobalt metal and cobalt compounds has been widely studied. Several publications show induction of chromosomal aberrations, micronuclei or DNA damage in mammalian cells in vitro in the absence of S9. Mixed results were seen in gene mutation studies in bacteria and mammalian cells in vitro, and in chromosomal aberration or micronucleus assays in vivo. To resolve these inconsistencies, new studies were performed with soluble and poorly soluble cobalt compounds according to OECD-recommended protocols. Induction of chromosomal damage was confirmed in vitro, but data suggest this may be due to oxidative stress. No biologically significant mutagenic responses were obtained in bacteria, Tk(+/-) or Hprt mutation tests. Negative results were also obtained for chromosomal aberrations (in bone marrow and spermatogonia) and micronuclei at maximum tolerated doses in vivo. Poorly soluble cobalt compounds do not appear to be genotoxic. Soluble compounds do induce some DNA and chromosomal damage in vitro, probably due to reactive oxygen. The absence of chromosome damage in robust GLP studies in vivo suggests that effective protective processes are sufficient to prevent oxidative DNA damage in whole mammals. Overall, there is no evidence of genetic toxicity with relevance for humans of cobalt substances and cobalt metal.

Nanoscale battery cathode materials induce DNA damage in bacteria

“…[10][11][12][13][14] More recently, Mitchell, et al showed that bacteria Shewanella oneidensis rapidly developed resistance to nano-NMC aer chronic exposure, indicating the potential effect of NMC on the genetic materials in biological organisms. 15 Such discoveries, along with the fact that nickel and cobalt ions are known to induce genotoxicity, 16,17 indicate that DNA damage is a likely potential toxicity mechanism of nano-NMC in bacteria.…”

Genotoxicity and oxidative stress induced by the orally administered nanosized nickel and cobalt oxides in male albino rats

“…Moreover, Co 3 O 4 -NPs are intensively used in many biomedical applications including imaging, cancer therapy, and gene therapy (Magaye, Zhao, Bowman, & Ding, 2012). However, the wide application of these MNPs led to their release into the environment in various ways resulting in an increased human exposure to these NPs via inhalation, oral ingestion, and dermal contact (Kirkland et al, 2015). Upon exposure, NPs can penetrate cells more rapidly and provide unprecedented toxicological interactions with cell biomolecules (Jeon, Park, Rhee, & Lee, 2010).…”

Biological activity of soil contaminated with cobalt, tin, and molybdenum

“…Co 2+ plays a quite important role in the human body because it is the central atom of cobalamin, a coenzyme precursor, whose deficiency causes anemia (Paustenbach et al 2013 ). Nevertheless, its genotoxic properties were also discovered, which should be taken into account in the overall Co 2+ assessment (Kirkland et al 2015 ).…”