Imma Perfetto
Cosmos science journalist
Experts are also calling for urgent work to understand the effects on humans and plants of a new chemical increasingly being used to replace TNT in explosives.
DNAN (2,4-dinitroanisole) is being increasingly used in explosive mixtures because it can be cast and melted more safely than TNT (2,4,6-trinitrotoluene).
But comparatively little is known about its impact on humans and the environment and how long it persists in soils.
A new Nature Plants study found that DNAN has similar effects to TNT, inhibiting growth and development in thale cress (Arabidopsis thaliana), which is widely used as a model organism in plant sciences.
But, where TNT only accumulates in roots, the research showed that DNAN accumulates throughout the whole plant and lingers in its tissues for longer.
“Similarly to TNT, DNAN reacts with a key plant enzyme, generating reactive superoxide which is highly damaging to cells,” says Neil Bruce, a professor in the Department of Biology in the University of York, UK, who led the new study.
TNT’s toxicity to plants, microorganisms, and invertebrates is well established. In previous studies, the team at the University of York even created grass that successfully degraded TNT contaminants to non-detectable levels in their tissues.
“We have genetically engineered plants to successfully detoxify land contaminated with munitions,” says Bruce.
“While plants can use natural processes to reduce the toxicity of TNT, our studies found that plants appear to have no natural way of fighting off the toxic effects of DNAN, meaning that it persists in the plant and is toxic at much lower concentrations.
“Unfortunately, DNAN is a very different story to TNT, as it accumulates in the above ground parts of the plant.”
The researchers warn that there is a greater risk of herbivores eating these contaminated above ground parts of the plant and introducing DNAN into the food chain.
“Recent years have seen an escalation in military explosives [use] due to global conflicts,” says study coauthor Dr Liz Rylott, also from the University of York.
“We are potentially looking at vast scales of pollution, which means there is an urgent need, and interest in, developing sustainable plant-based remediation strategies.
The study suggests there is an urgent need to understand the toxicity of DNAN in plants and whether they are capable of detoxifying concentrations that are likely to occur at contaminated sites.
“We also don’t know what the limits of DNAN toxicity are in humans,” adds Rylott.
“So, our hope is that our latest research will highlight that more work is urgently needed to understand its effects.”
